ArticlePDF Available

Can we beneficially reuse produced water from oil and gas extraction in the U.S.?


Abstract and Figures

There is increasing interest in beneficial uses of large volumes of wastewater co-produced with oil and gas extraction (produced water, PW) because of water scarcity, potential subsurface disposal limitations, and regional linkages to induced seismicity. Here we quantified PW volumes relative to water demand in different sectors and PW quality relative to treatment and reuse options for the major U.S. shale oil and gas plays. PW volumes from these plays totaled ~600 billion liters (BL, 160 billion gallons, Bgal) in 2017. One year of PW is equal to ~60% of one day of freshwater use in the U.S. For these plays, the total irrigation demand exceeded PW volumes by ~5× whereas municipal demand exceeded PW by ~2×. If PW is reused for hydraulic fracturing (HF) within the energy sector, there would be no excess PW in about half of the plays because HF water demand exceeds PW volumes in those plays. PW quality can be highly saline with median total dissolved solids up to 255 g/L in the Bakken play, ~7× seawater. Intensive water treatment required for PW from most unconventional plays would further reduce PW volumes by at least 2×. Desalination would also result in large volumes of salt concentrates, equivalent to ~3000 Olympic swimming pools in the Permian Delaware Basin in 2017. While water demands outside the energy sector could accommodate PW volumes, much lower PW volumes relative to water demand in most regions would not substantially alleviate water scarcity. However, large projected PW volumes relative to HF water demand over the life of the play in the Permian Delaware Basin may provide a substantial new water source for beneficial use in the future. Large knowledge gaps in PW quality, lack of appropriate regulations, and economic factors currently preclude beneficial uses outside the energy sector in most regions.
Content may be subject to copyright.
Can we benecially reuse produced water from oil and gas extraction in
the U.S.?
Bridget R. Scanlon
, Robert C. Reedy
, David Yoxtheimer
Qian Yang
, Svetlana Ikonnikova
Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, TX, United States of America
New Mexico State University, Civil Engineering Department, Las Cruces, NM, United States of America
Dept. of Geological Sciences, The University of Texas at El Paso, TX, United States of America
Earth and Environmental Systems Institute, College of Earth and Mineral Science, Penn State Univ., PA, United States of America
Irrigation demand exceeds produced
water volumes by 5 times.
Produced water quality is variable with
salinity up to 7× seawater.
Intensive treatment is required for pro-
duced water use outside of energy.
Produced water volumes would not
substantially alleviate overall water
Knowledge gaps related to produced
water quality preclude reuse outside of
abstractarticle info
Article history:
Received 20 December 2019
Received in revised form 31 January 2020
Accepted 1 February 2020
Available online 3 February 2020
Editor: Dr. Damia Barcelo
There is increasing interest in benecialuses of large volumes of wastewaterco-produced with oil andgas extrac-
tion (produced water,PW) because of water scarcity, potential subsurface disposal limitations,and regional link-
ages to inducedseismicity. Here we quantied PW volumes relative to waterdemand in different sectorsand PW
quality relative to treatment and reuse options for the major U.S. shaleoil and gas plays. PW volumes from these
plays totaled ~600 billion liters (BL, 160 billion gallons, Bgal) in 2017. One year ofPW is equal to ~60% of one day
of freshwater use in the U.S. For these plays, the totalirrigation demand exceeded PW volumes by ~5× whereas
municipal demand exceeded PW by ~2×. If PW is reused for hydraulic fracturing (HF) within the energy sector,
there would be no excess PW in about half of the plays because HF water demand exceeds PW volumes in those
plays. PW quality can be highly saline with median total dissolved solids up to 255 g/L in the Bakken play, ~7×
seawater. Intensive water treatment required for PW from most unconventional plays would further reduce
PW volumes by at least 2×. Desalination would also result in large volumes of salt concentrates, equivalent to
~3000 Olympic swimming pools in the Permian Delaware Basin in 2017. While water demands outside the en-
ergy sectorcould accommodate PW volumes, much lowerPW volumes relative to water demand in most regions
would not substantially alleviate water scarcity. However, large projected PW volumes relative to HF water de-
mand over the life of the play in the Permian Delaware Basin may provide a substantial new water source for
Science of the Total Environment 717 (2020) 137085
Corresponding author.
E-mail address: (B.R. Scanlon).
0048-9697/© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (
Contents lists available at ScienceDirect
Science of the Total Environment
journal homepage:
benecial use in the future. Large knowledge gaps in PW quality, lack of appropriate regulations, and economic
factors currently preclude benecial uses outside the energy sector in most regions.
© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://
1. Introduction
Co-production of large volumes of waste water or produced water
(PW) with theexpansion of energy production from shale or unconven-
tional oil and gas (UOG) plays within the past decade is becoming an
important topic because these plays are located mostly in the semiarid
western U.S. where water scarcity is a critical issue (Fig. 1)(Huang
et al., 2012;Reig et al., 2014;Scanlon et al., 2012). Water is also pro-
duced when coal beds are dewatered to mobilize methane, often
termed coal bed methane (CBM) (NASEM, 2010). Previous analysis es-
timated the total PW volumes in the U.S. to be ~3.4 trillion liters (TL;
3.4 km
~0.9 trillion gallons, Tgal) in 2012 (Veil, 2015), similar to previ-
ous estimates from 2007 (Clark and Veil, 2009). Most PW is injectedinto
the subsurface, with almost half of the 2012 volume injected into high
permeability conventional reservoirs, mostly for pressure maintenance
and enhanced oil recovery (EOR). In contrast, PW from UOG reservoirs
cannot be managed by disposal into the shale and tight rock reservoirs
because of the low permeability, but instead is injected into intervals
that do not produce oil and gas using salt-water disposal (SWD) wells.
This process affects the subsurface water budget, resulting in increased
pressures and has been linked to seismicity, particularly if disposal is ad-
jacent to basement rocks (Scanlon et al., 2019;Walsh and Zoback,
2015). Regulations were promulgated in Oklahoma and New Mexico,
restricting disposal of PW in certain units, such as the Arbuckle in Okla-
homa near the basement and its geological equivalent in New Mexico,
the Ellenburger, to reduce actual or potential induced seismicity
(Lemons et al., 2019;Scanlon et al., 2019). Additional adverse impacts
of subsurface disposal include contamination, with a recent analysis
suggesting that disposal wells may impact overlying aquifers in some
basins (Ferguson et al., 2018). Previous studies address a variety of
risks related to PW management, including pollution from spills and
leaks and casing failures (Meng, 2017;Torres et al., 2016).
Various PW management approaches have been suggested to re-
duce adverse environmental impacts, such as water scarcity, induced
seismicity, and contamination. The most obvious approach is to reuse
or recycle PW within the energy sector for hydraulic fracturing (HF) of
new wells in shale or tight oil plays. PW reuse would reduce water
sourcingto support HF. A recent analysis comparedPW supplies relative
to HF water demand in major U.S. plays, showing that PW reuse should
alleviate many of the adverse impacts of subsurface disposal; however,
some plays have PW volumes that exceed HF water demands (Scanlon
et al., 2020). PW reuse for HF was facilitated by advances in fracturing-
uid chemistry that shifted water-quality requirements for HF from
freshwater during the early years of UOG development to use of
clean brineswith minimal treatment in many regions (Barnes et al.,
2015;McMahon et al., 2015;Nichols et al., 2017). Although a large per-
centage of PW is reused for HF in the Marcellus and Fayetteville plays
(Greaves et al., 2017;Rassenfoss, 2011), the total volumes of PW in
these plays are low and can more readily be accommodated through
reuse for HF than in plays with much larger PW volumes, such as the
Permian Basin (Scanlon et al., 2017). New Mexico has changed its regu-
lations precluding landowners from requiring operators to purchase
water for HFwhen PW is available (New Mexico House Bill 0546). How-
ever, even in shale gas plays with low PW volumes, downturns in dril-
ling can temporarily limit the potential for reuse for HF, as seen in the
Fayetteville play (Greaves et al., 2017). Lack of reporting requirements
for PW reuse/recycling volumes makes it difcult to assess the extent
of PW reuse within the energy sector.
Fig. 1. Comparison of water demand for irrigation (2015), produced water volumes and hydraulic fracturing water demand (2017) for shale oil and gas reservoirs (Bakken, Niobrara,
Permian [Midland and Delaware basins], Eagle Ford, Barnett, Oklahoma Area of Interest [AOI], Haynesville, Fayetteville, and Marcellus) and coal bed methane reservoirs (Powder River,
San Juan, Uinta, and Black Warrior basins). See Fig. S1 for units in billion gallons.
2B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
Another approach for managing PW is to reuse it outside of the en-
ergy sector, such as in irrigation, municipal, and industrial sectors, or
to discharge treated PW to surface water or to recharge groundwater.
The feasibility of using PW for irrigation was evaluated for Colorado
(Dolan et al., 2018). A recent study by the U.S. Groundwater Protection
Council (GWPC) evaluated the potential for benecial use within and
outside the energy sector, focusing on legal and regulatory issues and
research needed to ensure safe use of PW in other sectors (GWPC,
2019). New Mexico developed a Memorandum of Understanding with
the U.S. Environmental Protection Agency (EPA) to assess regulatory
frameworks for PW reuse within and outside the energy sector, includ-
ing discharge to surface water (Danforth et al., 2019;USEPA, 2018).
Benecial uses of PW outside the energy sector will require much
more intensive water treatment than that required to support HF
where minimal treatment (clean brine) is sufcient. However, charac-
terizing all of the constituents in PW, including owback water from
HF, is complicated because of difculties with analytical techniques,
problems with high salinity matrices, and lack of appropriate reference
materials (Oetjen et al., 2017;Tasker et al., 2019). Less than a quarter of
the ~1200 chemicals identied in PW have an approved analytical tech-
nique (Danforth et al., 2020). There is a lack of toxicological information
for the majority of chemicals found in PW (Danforth et al., 2020).
Treatment technologies for PW are continually advancing, and selec-
tion of appropriate technologies will depend on the PW quality, water-
quality requirements for reuse options, and treatment economics. To
optimize PW reuse, t-for-purpose treatment will be essential to mini-
mize costs. Total Dissolved Solids (TDS) of PW from many UOG reser-
voirs may be too high (i.e. ~40 g/L) for traditional reverse osmosis
(RO) approaches, and more complex thermal distillation approaches
may be required. Management of concentrates is also an important
issue and can greatly increase treatment costs. Current water quality
standards for different sectors, including irrigation and public water
supplies, are insufcient for assessing the feasibility of using PW in
these sectors because the standards did not consider many of the con-
stituents present in PW (GWPC, 2019). For example, the standards for
public water supplies only include 90 contaminants in the EPA primary
list, with most contaminants listed N20 years ago. The limited under-
standing of the toxicity of PW constituents underscores the risks and
hazards to humans and the environment from reuse outside of the en-
ergy sector (Danforth et al., 2019).
Projected exponential increases in PW from tight oil plays (Scanlon
et al., 2020) raise the question about the adequacy of subsurface dis-
posal capacity to accommodate the PW increases. Recent projections
of PW over the life of the plays range from 1.1 TL (0.3 Tgal) in the
Eagle Ford to 49 TL (13 Tgal) in the Permian Basin (Scanlon et al.,
2020). The projected PW volumes in the Permian represent ~3× water
use in the state of Texas in 2017 (17 TL, 4.6 Tgal). Therefore, potential
water scarcity, groundwater contamination, and induced seismicity
concernsunderscore the need to assess the potentialto develop bene-
cial uses for PW to partially mitigate these issues.
The objectives of this study are to address the following questions:
What is the potential for benecially using PW from UOG reservoirs
outside the energy sector based on volumetric water budgets?
How feasible is benecial use of PW considering water quality issues?
This study builds on a previous analysis that focused on reuse of PW
from UOG reservoirs within the energy sector (Scanlon et al., 2020). In
the current study, we examined a variety of potential benecial uses
for PW outside of the energy sector (Fig. 2). We quantied PW volumes
relative to water demand for different sectors, including irrigation, mu-
nicipal, livestock, and industrial uses. We briey discussed issues with
discharge to surface water and recharge to groundwater. The analysis
covers the major UOG and CBM plays in the U.S., leveraging off of previ-
ous studies that quantied different components of the system in vari-
ous regions (Graham et al., 2015;Horner et al., 2016;Kondash et al.,
2017;Nicot et al., 2014;Scanlon et al., 2017). We do not consider PW
from conventional reservoirs because this is mostly reinjected into the
high permeability reservoirs with minimal adverse environmental im-
pacts. However, we recognize that if incentives are created to reuse
PW, operators may also consider PW from conventional reservoirs
Fig. 2. Benecial use of produced water withinthe energy sector (hydraulic fracturing) and outside the energy sector (irrigation, municipal, industrial, livestock), surface water discharge
(evaporation ponds, stream discharge) and groundwater recharge.
3B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
which could greatly increase the volumes of PW available for reuse. For
example, PW volumes from the Permian conventional reservoirs were
~10× greater than those from unconventional reservoirs (20052015)
(Scanlon et al., 2017). We also evaluated the lifespan of PW from se-
lected plays (Bakken, Eagle Ford, Marcellus and Permian plays) based
on projected PW volumes,which is important for evaluatingthe reliabil-
ity of PW feedstock for developing treatment options. This study com-
plements the recent GWPC report assessing the feasibility of benecial
use of PW in different sectors by providing quantitative data on the rel-
evant water volumes (GWPC, 2019). PW quality was evaluated using
existing data from the USGS Produced Waters database (Blondes et al.,
2017) and literature studies. Treatment options for PW reuse were ex-
amined and salt concentrate management was evaluated. The quantita-
tive data provided in this assessment will be valuable to regulators and
policy makers evaluating different options for managing PW.
2. Materials and methods
The primary emphasis of this study was on major shale oil and gas
plays within the U.S., often referred to as tight oil and shale gas
(Fig. 1). The UOG plays evaluated include the Oklahoma Area of Interest
(AOI in terms of high seismicity), Bakken, Barnett, Eagle Ford, Fayette-
ville, Haynesville, Marcellus, and Permian (Midland and Delaware Ba-
sins) plays. Water issues related to selected CBM plays were also
examined, focusing on the Black Warrior, Powder River, Uinta, and
San Juan plays. CBM plays were evaluated becausethey have a long his-
tory of PW management and they represent an end member in terms of
TDS because the PW TDS is generally much lower than that from UOG
2.1. Volumetric water budgets
The potential for benecial use of PW depends on synergy between
PW supplies and sectoral water demands and alignment of PW quality
relative to quality requirements for different sectors. Data on PW vol-
umes are available for ~100,000 UOG wells in the U.S.from state records
and commercial databases (IHS Enerdeq). These data do not consider
any reuse of PW for HF. Data on PW from 2017 were used in the analysis
because PW reporting lags by at least one year in many of the plays
(Texas plays: Barnett, Eagle Ford, Permian, and Haynesville). PW vol-
umes in excess of HF water demand in 2017 were also calculated for
the scenario with maximum reuse of PW for HF within the energy sector
prior to considering reuse outside the energy sector. Water demand for
different sectorsincluding irrigation, municipal, and industrial sectors
was obtained from the U.S. Geological Survey (USGS) compilation
using the most recent data from 2015 (Dieter et al., 2018). PW volumes
(2017) were compared to water demands for various sectors (2015) at
the play level and also at the county level, the lowest spatial unit in-
cluded in the USGS water use database. Projections of PW were com-
pared with projections of HF water demand based on previous
analysis of technically recoverable resource assessment over the life of
the play, assuming all potential wells will be drilled using current tech-
nology (Scanlon et al., 2020). Data on projections are available for the
Bakken, Eagle Ford, Permian, and Marcellus plays.
2.2. Produced water quality
Data on PW quality were obtained from the USGS Produced Wa-
ters database, which is based primarily on conventional oil and gas
reservoirs and CBM plays (Blondes et al., 2017). Details related to
the data used in this study, including numbers of samples, types of
analyses (TDS, major and trace element chemistry), and time periods
covered are provided in Table S26. Additional data were obtained
fromtheliteraturebasedoneld studies of sampling in selected
UOG plays. Most focus was placed on total dissolved solids (TDS) to
evaluate water treatment options and treatment goals; however,
we recognize that the TDS data alone are insufcient for assessing
PW reuse outside of the energy sector. In particular, organics can
be toxic at low concentrations, and analytical tools to determine
presence and concentration of organics are limited. Data on major
and trace element chemistry were also compiled, and we included
analyses that had charge balances within ±15%. We reviewed treat-
ment technologies based on PW quality and water quality require-
ments for different sectors or for discharge to surface water or
recharge to aquifers. Options for managing concentrates were also
examined because they can greatly affect costs.
3. Results and discussion
3.1. Spatiotemporal variability in produced water supplies
PW volumes totaled ~600 BL (0.6 km
; ~160 Bgal) in 2017 from eight
major UOG reservoirs (Fig. 1,Table 1). These eight plays account for 88%
of tight oil and 84% of shale gas production in the U.S. based on 2018
data. PW volumes were much higher in western unconventional oil
plays than in eastern unconventional gas, with 50× higher PW in the
Permian oil play relative to the Marcellus gas play in 2017. PW volumes
were much lower from CBM plays, totaling 46 BL (12 Bgal) in 2017.
Benecial use of PW would require a reliable supply of PW or feed-
stock. The only play with continuously increasing total PW volumes
over the past decade is the Permian Basin, where PW volumes increased
by ~20× from 2011 to 2017 (Fig. 3a). PW volumes are not reported in
Oklahoma but are approximated by SWD volumes which have
remained fairly stable over the past several years at ~250 BL/yr (~65
Bgal/yr). PW volumes in many of the plays peaked in 2011 or 2014
and generally declined since then with decreasing oil and gas prices or
resource depletion (2011 peak: Barnett, Fayetteville; 2014 peak: Eagle
Ford, Bakken). PW from CBM plays peaked in 2009 and generally de-
clined since then because of the reduction of CBM production (Fig. 3b,
Fig. S2). For example, volumes of PW in the Powder River Basin (Wyo-
ming) peaked in 2008 and declined by ~80% in 2017. The Permian
Basin seems to provide the most reliable long-term PW feedstock
based on the increasing PW volumes.
PW volumes available for benecial use in other sectors decrease
substantially if the PW is rst reused within the energy sector for HF
(Fig. 1,Table 1). Reuse within the energy sector should be maximized
because it represents the lowest risks relative to reuse in other sectors.
HF water volumes exceeded PW volumes in about half of the plays;
therefore, PW reuse for HF could potentially use up all of the PW de-
pending on logistics. In contrast, PW exceeded HF water use in the re-
maining half of the plays (Bakken, Barnett, Oklahoma, and Permian
Delaware basins). For example, PW in the Permian Delaware Basin
was almost 2× HF water use in 2017. However, lack of reporting of PW
reuse for HF precludes quantication of the extent of reuse within the
energy sector. Other factors work against PW reuse for HF, such as land-
owners and organizations requiring operators to purchase water from
them as part of lease agreements in Texas. For example, HF water de-
mand in the Permian would represent ~$0.5 billion in 2017 based on
local water charges (~$2.2/1000 L; $0.35/barrel) (Scanlon et al., 2017).
The previous analysis focused on PW data from 2017. Projections of
PW and HF water are also important for assessing the potential for PW
reuse in the future. These data are available for the Bakken, Eagle Ford,
Permian, and Marcellus plays (Scanlon et al., 2020). The potential for
reuse outside of energy is similar for the projections and 2017 data for
most plays except for the Permian Delaware Basin, where the ratio of
PW/HF water doubles over the life of the play (ratio: 3.6) relative to
2017 (ratio: 1.8). The increase in the ratio is attributed to the age of
the well population, which is young in 2017 but increases substantially
over the life of the wells (~20 yr). Therefore, there should be increased
opportunity for reuse of PW outside of HF water demand in the Permian
Delaware Basin within the next couple of decades.
4B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
How long will PW be available for benecial use? The PW volumes
are projected to last ~25 yr for the Bakken and Eagle Ford plays, ~50 yr
for the Permian Midland Basin, and ~70 to 80 yr for the Permian Dela-
ware and Marcellus plays (Table 1). These estimates are based on
projected well inventory over the life of the plays (Scanlon et al.,
2020) divided by the historical maximum drilling rate. Therefore, PW
supplies would provide the most reliable feedstock in the Permian Del-
aware Basin.
Most of the PW from UOG reservoirs has been managed by subsur-
face injection using SWD wells. Although PW and SWD volumes are re-
ported separately without any direct linkage between the two, the
reported SWD volumes provide a check on PW volumes (Table 1).
SWD volumes are high in the Permian Basin and Haynesville plays but
include PW from both unconventional and conventional reservoirs. Cu-
mulativePW and SWD volumes aresimilar in the Bakkenand Eagle Ford
plays. PW from CBM plays has not been managed using subsurface dis-
posal butmostly surface disposalin ponds, as described in a latersection.
3.2. Assessing water demand in different sectors relative to produced water
3.2.1. Irrigation sector
The sector with the largest water demand is irrigation (2015 data),
exceedingPW volumes in UOG plays (2017 data)by ~5× and exceeding
PW volumes from CBM plays by ~50× (Fig. 1). Irrigation is concentrated
mostly in the western U.S. (Figs. 4, S3). Box plots of water use in differ-
ent sectors are provided in Figs. S4 and S5 and Tables S4 through S13.
The much higher irrigation volumes relative to PW volumes at the
play level means that the irrigation sector should be able to accommo-
date the PW volumes. If PW is reused for HF within the energy sector,
there would be no excess PW in about half of the plays because HF
water demand exceeds PW volumes in those plays (Table 1). The irriga-
tion to PW ratio is similar in the remaining plays (ratio: 5). Irrigation
could accommodate excess PW volumes in these plays, including the
Permian Delaware (irrigation/excess PW ratio: ~10×) and Bakken
(ratio: 30×) plays but not in Oklahoma AOI (ratio: ~0.6). There is also
a temporal disconnect between PW, which is generated throughout
the year, and irrigation demand, mostly restricted to summer months.
Irrigation at the play level was highest in the Niobrara (870 BL, 230
Bgal) and Permian Basin (~840 BL, ~220 Bgal) plays in 2015 (Table 1).
Although most (96%) PW in the Niobrara is from a single county
(Weld County), HF water use exceeds PW in this county by ~4× and
could reuse all of the PW (Fig. S10, S19; Table S18). If PW was used
for irrigation, it would contribute only ~1% to irrigation in this county,
Table 1
Volumes (10
L) of produced water (PW), saltwater disposal (SWD), and hydraulic fracturing (HF) water during 2017 compared with irrigation (Irrig) and municipal (Muni) water use
during 2015 and projected remaining totalPW volumes. Also listed are the remaining yearsof well completion activity based on the projected well inventory and historical annual max-
imum numberof wells drilled per year forselected plays. For moredetails on the projections, see Scanlon et al., 2020.Data for additionalsectors are provided in metricand English units in
Table S1. County level data for each play are provided in Tables S4 and S5.
Play name 2017 2015 Projected
PW SWD HF Irrig Muni PW HF water Well invent. Max. wells
per yr
Rem. yrs
TO Permian 264.4 378.6 210.2 841.7 65.1 49,300 18,200 320,000 5,000 64
TO Delaware 164.2 217.7 90.8 708.7 54.0 39,400 10,800 207,000 2,600 80
TO Midland 100.3 160.9 119.4 132.9 11.1 9,900 7,400 113,000 2,400 47
TO OK AOI 195.3 195.3 28.0 108.7 270.1 –– –
TO Bakken 54.6 56.7 29.3 747.5 18.8 2,500 1,700 69,000 2,700 25
TO Eagle Ford 35.1 38.9 66.2 219.1 144.6 1,100 3,200 105,000 4,000 26
TO Niobrara 6.7 6.4 28.0 867.4 362.8 –– –
SG Barnett 42.5 42.5 1.4 32.9 134.2 –– –
SG Marcellus 5.3 26.0 3.9 161.6 2,200 5,200 124,000 1,700 73
SG Haynes. 2.2 45.0 3.6 2.6 76.4 –– –
Total 606 763 393 2824 1234 55,100 –– – –
CBM PRB 26.1 ––1,172.5 18.4 –– –
CBM Raton 7.8 ––103.8 7.3 –– –
CBM San Juan 5.7 ––855.5 36.5 –– –
CBM BW 4.9 ––16.9 171.7 –– –
CBM Uinta 1.7 ––227.6 9.9 –– –
Total 46.2 ––2,376 243.8 –– –
TO: TightOil; SG: Shale Gas;CBM: Coal Bed Methane;Haynes: HaynesvillePlay; PRB: PowderRiver Basin; BW, BlackWarrior Basin;PW volumes are notreported for theOklahoma AOI but
are approximated bySWD volumes. PW and SWDvolumes are assumedequal in the Barnettbecause of uncertainties inPW volumes. The Permiandata representthe sum of data from the
Midland and Delaware basins and do not include development outside of these basins.
Fig. 3. Timeseries of produced water(PW) volumes fora) the major tight oil andshale gas
plays and b) the coal bed methane plays. Data for Oklahoma represent statewide values.
The data are tabulate d in Tables S2 a nd S3.
5B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
with little impact on water scarcity. These results are consistent with
previous ndings (Dolan et al., 2018;Walker et al., 2017). Irrigation
exceeded PW volumes by ~3× in the Permian Midland and Delaware
Basins (Table 1). The most intensive irrigation is generally north of the
UOG development (~2500 BL; 660 Bgal), ~3× irrigation in the Midland
and Delaware Basins (Fig. 4). PW represented 1%, 12%, and 17% of irriga-
tion demand in counties with the highest irrigation (Eddy, Lea, and
Pecos counties (2017) in the Permian Delaware basin) (Fig. S6,
Table S14). These percentages would decrease to bb1%, 5%, and 11% if
PW was reused to meet HF water demand in these counties. Counties
with large volumes of PW relative to irrigation (e.g. Midland County:
PW/irrigation ~30) could support expansion of irrigation, but PW in
this county represents ~3% of irrigation in the Permian. Irrigation in
the Eagle Ford exceeded PW volume by ~6× (Table 1), with most irriga-
tion in a few counties where PW would contribute b1% to irrigation de-
mand. However, HF water use exceeded PW in most counties by up to
23×; therefore, reuse of PW for HF would eliminate the PW source
for irrigation. Irrigation in the Bakken/Three Forks is mostly restricted
to a few counties, with PW accounting for b1% of irrigation in most
counties. Total irrigation in the Oklahoma AOI is less than the PW vol-
ume but varies spatially (Table 1). Irrigation is generally much higher
than PW volumes in the western CBM plays, ~45× PW in the Powder
River Basin (Table 1), with PW contributing b5% to irrigation in most
counties (Fig. S14, Table S23).
In summary, irrigation could accommodate PW volumes in various
regions of western plays; however, the high ratios of irrigation to PW
in many counties suggest that PW volumes would not substantially re-
duce water scarcity in these regions. In many cases, HF water demand
exceeds PW volumes and would eliminate the PW source for irrigation
if PW was reused within the energy sector. In the past, water transfers
generally occurred from the irrigation sector to the oil and gas sector
for HF in some plays, e.g., Bakken/Three Forks, Niobrara, and Permian
plays (Horner et al., 2016;Kurz et al., 2016;Scanlon et al., 2016;Shuh,
2010). However, lack of reporting of water sourcing for HF makes it dif-
cult to track water transfers among sectoral users.
3.2.2. Municipal, livestock, industrial, and mining sectors
Many of the UOG reservoirs are located in rural areas with minimal
municipal water use. Total municipal water demand in 2015 in the
area of UOG reservoirs exceeded PW volumes in 2017 by ~2×
(Table 1). Municipal demand was highest in the Niobrara (30% of total
water demand) and Oklahoma AOI (22%), followed by the Barnett,
Eagle Ford, and Marcellus (11%13%). PW would represent b0.1% of mu-
nicipal demand in Niobrara counties with high municipal demand
(Fig. S10). About 50% of the municipal demand in Oklahoma AOI is in
OklahomaCounty, where PW would constitute ~3% of the municipal de-
mand (Fig. S7). Similarly in the Marcellus, municipal demand was
highest in a couple of counties, but PW would only represent 3% of
this demand because of the low PW volumesin this play (Fig. S12).Mu-
nicipal demand in CBM plays was ~5× PW volumes, mostly in the Ala-
bama portion of the Black Warrior Basin (Table 1). PW would
represent 8% of municipal demand in the Black Warrior Basin. In sum-
mary, PW would contribute minimally to municipal demand in most
cases from a volumetric standpoint. In the past, water has generally
been transferred from the municipal sector to UOG reservoirs for HF in
the Barnett, Niobrara, and Permian plays, either from freshwater or
treated municipal waste water (Nicot et al., 2014;Scanlon et al., 2017;
Walker et al., 2017).
Water use for livestock was ~25% of total PW volume in UOG reser-
voirs in 2017 and was highest in the Haynesville and Eagle Ford plays
(Table 1). Counties with high livestock water demand generally did
not coincide with relatively high PW volumes in these plays. Livestock
water use was negligible in CBM plays.
Total volumes for industrial water uses were generally low in UOG
and CBM regions (Table S1). The industrial water use category refers
to self-supplied withdrawals for the industrial sector (Dieter et al.,
Thermoelectric cooling for power plants requires large water with-
drawals in once-through cooling systems, but consumption equals
only a few percentof withdrawal (Dieter et al., 2018). This studyfocused
on the consumptive water use for recirculating cooling towers, which
Fig. 4. Distributionof irrigated landsin the U.S. based on composite satellite images for 2002,2007, and 2012 basedon Moderate Resolution Imaging Spectroradiometer (MODIS)Irrigated
Agriculture Dataset for the United States (MIrAD-US) ( The various play regions discussed in this study are highlighted. The area of focused
unconventional oil and gas development located in a 19-county region of the Permian Basin is also outlined within the basin, showing most intensive irrigation north of the UOG
6B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
have lower water withdrawals and similar rates of water consumption
than once-through systems. Water use for recirculating cooling was
low, ~20% of PW, highest in the Oklahoma AOI (Table S5). PW would
represent 23%45% of cooling water use in counties with the highest
water demand for these plants (Noble and Oklahoma counties).
The mining water use sector includes water use for extraction of
rocks and minerals (e.g. coal, sand, and gravel) and fossil fuels
(Table S1) (Dieter et al., 2018). However, the mining values are difcult
to interpret because they do not seem to be internally consistent. The
mining values should include HF water but are less than HF water in
the Marcellus and Niobrara, are similar to HF water in the Bakken, and
are similar to HF water + PW in Texas plays (Barnett, Eagle Ford, and
Permian). Therefore, the mining sector does not seem to provide an op-
portunity for reuse of PW. There may be some local cases where PW
could be used in another mining sector. For example, PW could be
used for potash mining in New Mexico; however, the potash mines
are currently selling water to UOG operators because potash prices are
low (Hayden, 2017).
In summary, the most obvious sector for reuse of PW from a volu-
metric perspective is irrigation. With irrigation greatly exceeding PW
volumes, it can accommodate the PW volumes in semiarid oil plays
where PW volumes are highest. However, the PW volumes represent
a small percentage of irrigation demand in most counties, particularly
if PW is rst reused for HF; therefore, PW will not substantially help re-
duce water scarcity concerns in these plays.
3.3. Surface water discharge and managed aquifer recharge
Additional benecial uses of PW include discharge to surface water
and recharging groundwater. Most PW from CBM plays has been
discharged at the surface into unlined impoundments in Wyoming
(~4000 permits by 2007) (Healy et al., 2011) or discharged to rivers,
such as the Black Warrior River in Alabama, without any or with mini-
mal treatment (e.g. settling ponds). Comparing PW volumes with ow
in the Black Warrior River, which is in a humid region, suggests that
river discharge exceeds rates of PW generation by ~50 times during
low ows and up to 400 times during normal ows (SI, Section 1a).
Treated PW has also been discharged to surface water in the Marcellus
play; however, there were contamination issues during the early years
(SI, Section 1b). Incentives in the form of a tax credit ($0.13/barrel;
$0.01/L) were put forward by New Mexico to promote discharge of
treated PW into the Pecos River (SI, Section 1c). However, PW discharge
from oil and gas wells within a 50 km corridor of the Pecos River (arid
setting) would exceed annual stream discharge mostly by factors of
410× but up to 20× in dry years and by much greater values during ex-
tremely dry years (Fig. S30b). The natural water quality in the Pecos
River is quite variable, with total dissolved solids ranging from 1.6 to
17 g/L in different gages along the river based on USGS data (https:// In summary, river discharge in humid re-
gions greatly exceeds PW volumes, increasing the assimilative capacity
of the rivers for treated PW. In contrast, rivers in semiarid regions are
mostly ephemeral and discharge is much less than the PW volumes,
complicating discharge of treated PW.
The feasibility of groundwater recharge and aquifer storage and re-
covery (ASR) is also being considered in some plays, such as the Perm-
ian Basin. However, the risks related to such a practice seem high, and
potential unintended consequences large. Storing excess PW in the sub-
surface would provide a means to resolve PW supply relative to water
demands for different sectors. An alternative to aquifer storage would
be to use deeper geologic units currently used for salt water disposal,
such as the Delaware Mountain Group in the Permian Delaware Basin
or the San Andres Formation in the Permian Midland Basin (Lemons
et al., 2019). Pumping water from these units to support HF would re-
duce overpressuring from SWD and potential contamination of overly-
ing aquifers (Ertel and Bogdan, 2017;Landis et al., 2016).
3.4. General quality of produced water
Produced water can contain oil and grease droplets, suspended
solids, major elements, transition metals, naturally occurring radioac-
tive material (NORM), organic compounds, and microbes. Chemicals
present in HF uids as reported in FracFocus ( may also
be contained in PW, particularly during the early stages of production.
Data on PW quality aredominated by analyses from conventional oil
and gas reservoirs from the USGS PW database, with limited data from
UOG reservoirs (Blondes et al., 2017). TDS provide a general indication
of the mineral content of the PW with implications for water treatment
and for salt management. Median TDS is highest in Bakken tight oil
(244 g/L), ~7× that of sea water (Figs. 5, 6). TDS is moderately high in
the Permian tight oil play (median: 154 g/L) and the Appalachian (Mar-
cellus) shale gas play (166 g/L), with a lower value in the Eagle Ford
shale play (57 g/L). The Permian TDS data include PW from unconven-
tional units, such as the Wolfcamp and Cline Shales, along with wells
specically designated as unconventional in the USGS database. The
highest TDS (99th percentile) in shale oil and gas plays ranges from
300 to 370 g/L, with a lower value in the Eagle Ford play (~180 g/L)
and Niobrara (95 g/L). No systematic difference exists between TDS in
conventional and unconventional reservoirs as seen from the USGS da-
tabase. There can be substantial variability in TDS within plays, bothar-
eally and vertically (Fig. 5). Recent analysis of Permian data reveals the
highest TDS in shallower zones near salt deposits and decreasing TDS
with depth (Chaudhary et al., 2019). Inthe Eagle Ford play, a salinity re-
versal and freshening of PW (a factor of 10 reduction in TDS from
~200 g/L at 2.5 km [1.6 m] depth to ~20 g/L at 3.5 km [2.2 m] depth)
was noted and attributed to clay conversion from smectite to illite
with interlayer water release (Nicot et al., 2018). PW from CBM plays
is generally much fresher than that from the shale oil and gas plays,
with median TDS ranging from ~1 g/L in the Powder River Basin to ~
11 g/L in the Uinta Basin (Fig. 5).
PW from tight oil and shale gas plays is dominated by Na (median:
1576 g/L) and Cl (median: 22150 g/L) (Fig. S31), consistent with pre-
vious studies indicating that nearly all basinal waters N10 g/L TDS are
dominated by Na\\Cl, with other ions existing only as minor or trace
constituents (Hanor, 1994). Levels of Ca are generally much lower
(~0.313 g/L). Sulfate levels are mostly low (median:
0.0200.675 g/L). PW from CBM plays is dominated by Na and Cl in
the Black Warrior and Uinta Basins but Na and HCO
in the Powder
River, San Juan, and Raton Basins, reecting marine versus terrestrial
depositional environments (Fig. S32). Low sulfate concentrations in
PW from CBM plays are attributed to methanogenesis. Median sodium
adsorption ratios (SARs), important for irrigation, are generally high in
PW from CBM plays but vary considerably among the plays studied,
with medians ranging from 7 to 294 in different basins (Fig. S33).
SARs N3 generally require freshwater to ush the salts in irrigated
lands, and SARs N13 can degrade soil texture (SI, Section 1d).
Data on minor or trace elements in PW are limited. Here we only
mention naturally occurring radioactive material (NORM) in PW,
which mostly consists of
Ra (half life: 5.75 yr) and
Ra (half life:
1600 yr) derived from U and Th in the reservoir (Guerra et al., 2011).
Total Ra (
Ra +
Ra) levels greatly exceed the EPA regulatory limit
of 5 pCi/L (pico curies/L) for drinking water but are higher in the Marcel-
lus shale (median: 1980 pCi/L) and the Bakken (1,200 pCi/L) than in the
Permian (535 pCi/L) or Eagle Ford (284 pCi/L) (Fig. S31).
3.4.1. Sources of produced water
Combinations of compositional and isotopic data provide signicant
insight into the origin of PW from oil and gas reservoirs. The presence of
Cl as the dominant anion in nearly all PW with salinity N10 g/L and max-
imum TDS concentrations several times seawater (35 g/L TDS) suggest
that the dominant source of PW and ions is evaporated seawater and/
or dissolution of Cl-bearing evaporites. Studies of UOG plays, including
the Bakken, Marcellus, and Permian Basin, conclude that these same
7B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
solute and water sources also dominate most shale reservoirs (Engle
et al., 2016;Lauer et al., 2016;Rowan et al., 2015). Black shale specic
processes, such as hydrocarbon maturation, clay diagenesis, and
water-clay interactions, have also been shown to control the composi-
tion of PW from unconventional plays (Engle et al., 2016;Nicot et al.,
2018;Phan et al., 2016;Stewart et al., 2015).
Sources of water and solutes in CBM plays vary depending on geo-
logic history and depth. Low TDS (median: 2.9 mg/L) Na-Cl-type waters
found in much of the Black Warrior Basin indicate a marine origin
(Pashin et al., 2014), with even lower TDS (median ~1 g/L) Na-HCO
rich water from the Powder River Basin reecting meteoric water that
has undergone a series of geochemical reactions within the coal beds
from which they are produced (Brinck et al., 2008).
3.4.2. Evaluating water quality requirements fordifferent sectors relative to
produced water quality
There is a long history of assessments of potential reuse of PW from
CBM plays for irrigation and surface water discharge (Arthur et al.,
2005;Guerra et al., 2011). CBM PW discharges are managed outside of
national programs and are subjected to local permitting requirements.
PW from CBM plays is of much higher quality than that from shale
UOG plays, with median TDS values of 111 g/L (Fig. 6). In addition,
CBM PW does not contain the chemicals from HF. However, CBM PW
does contain polycyclic aromatic hydrocarbons from the associated
coal (Orem et al., 2014). For example, PW in the Black Warrior Basin
(median TDS: ~4 g/L) is discharged directly to the Black Warrior River
in Alabama where it is diluted (SI, Section 1a). However, some issues re-
lated to use of CBM PW for irrigation include SAR and negative impacts
on soil inltration and other toxic constituents, such as boron etc. (SI,
Section 1d). Use of high quality PW from CBM for irrigation can leach
salts from semiarid soils, resulting in poor quality water reaching
Fig. 5. Total dissolved solids (TDS) of produced water from the USGS Produced Waters database (version 2.3) with supplemental data for the New Mexico region of the Permian Basin
providedby the New Mexico Instituteof Mining and Technology(NMIMT) PetroleumResearch and Recovery Center (PRRC), and data fromthe USGS in the Eagle Ford Play. Labeled values
represent median produced water TDS concentrationswithin each play area of wells classied as eithershale gas, tight oil, or coal bed methane, with the exception of the Permian value,
which includes wells that are classied as conventional hydrocarbon wells completed in unconventional formations (i.e., Wolfcamp, Bone Spring, Cline, Spraberry, and Dean). Data are
provided in Table S26.
Fig. 6. Total dissolved solids (TDS) for tight oil (T O) and shale gas (SG) reservoirs
(unconventional oil and gas reservoirs), conventional oil and gas reservoirs (Conv), and
coal bed methane (CBM) reservoirs. The Bakken unconventional tight oil includes the
Bakken and underlying Three Forks units. Coal bed methane reservoirs include Powder
River, Raton, Black Warrior, and Uinta basins. The numb ers at the base refer to the
number of analyses. For locations of reservoirs, see Fig. 1. The USGS data are provided in
Table S26. Additional data were obtained from Nicot et al. (2018).
8B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
underlying aquifers, with up to100 g/L TDS in groundwater near an im-
poundment in Wyoming (Healy et al., 2011).
Water quality standards and regulations for water use in irrigation,
livestock, and municipal sectors (drinking water maximum contami-
nant levels and irrigation and land application standards) do not con-
sider many of the risks related to use of PW from UOG reservoirs and
are not appropriate for assessing such use (GWPC, 2019). For example,
the EPA primary drinking water regulations include ~65 contaminants
within the chemical contaminant rules, including inorganics and vola-
tile and synthetic organics (
contaminant-rules). Assessing treatment of PW by comparing with
drinking water standards is insufcient because the regulations were
not designed to consider PW.
Surface discharges of PW from UOG wells are regulated under the
National Pollution Discharge Elimination System (NPDES) and related
national efuent-limitation guidelines or corresponding state regula-
tions (GWPC, 2019). The EPA prohibits discharge of PW from UOG
plays to public-owned treatment works, but PW can be discharged to
Centralized Water Treatment (CWT) facilities.
Because of the large number of potential organic contaminants in
PW and difculties in analyzing many of these elements within the con-
text of high salinity matrices (Danforth et al., 2019;Luek and Gonsior,
2017;Nelson et al., 2014;Oetjen et al., 2017), it seems infeasible to con-
duct a comprehensive evaluation of PW chemistry. Detailed risk assess-
ment will be required to evaluate potential human health and
environmental impacts of benecial PW reuse outside of the energy sec-
tor. The GWPC report outlines many of the aspects of a suitable risk as-
sessment, building on previous studies (NRC, 2009). Whole efuent
toxicity (WET) assessment is proposed to address known and potential
unknown contaminants (GWPC, 2019).
4. Treatment options for produced water reuse applications
Selection of the appropriate treatment technologies depends pri-
marily on two factors:
(1) the quality of the input water or feed water, particularly salinity
and other inorganic and organic constituents, and
(2) the quality of the water that is generated relative to the require-
ments for benecial use.
Recovery efciency and waste generation from treatment are also
important factors.
4.1. Desalination of produced water for industrial, agricultural, and potable
Removal of dissolved solids (desalination) is required for applications
that require high water quality. Two primary technologies currently used
for water desalination include those based on (1) membrane technologies
or (2) thermal technologies (Fig. 7). Additional information on treatment
technologies is provided in SI, Sections 2 and 3.
Membrane technologies include electrodialysis (ED), electrodialysis
reversal (EDR), nanoltration (NF), and reverse osmosis (RO). NF and
RO use high hydraulic pressure to diffuse pure water through a dense
non-porous membrane and retain solutes on the feed water side of the
membrane. In general, RO is capable of treating PW with TDS up to
~40 g/L due to the limitation of pressure vessels; however, RO becomes
too energy intensive and expensive at much lower levels of TDS
(~1535 g/L). Water recovery varies with salinity, ranging from 30% to
60% for seawater (35 g/L) to 60% to 85% for brackish water (10 g/L)
(Igunnu and Chen, 2014). RO treatment is effective in removing almost
all inorganic contaminants, including NORM; however, additional ana-
lytical techniques are required to determine whether some organics re-
main in the treated water. To minimize membrane scaling and fouling,
RO requires extensive pretreatment to remove sand, silt, clay, algae, mi-
crobes, colloidal particles and large molecular organics (e.g., petroleum
hydrocarbons), and sparingly soluble salts. RO has been applied to PW
from the Marcellus, Barnett, and Fayetteville plays (ALL, 2010).
Thermal technologies (e.g., multiple-effect distillation [MED], me-
chanical vapor compression [MVC] and recompression [MVR]) are al-
most independent of source water salinity (Fig. 7). Thermal distillation
technologies involve heating and evaporating feed water followed by
condensation of pure water. Typical water recoveries range from 20%
to 35% for MED to 40% for MVC (Igunnu and Chen, 2014). These low
water recoveries result in large volumes of concentrate that need to
be disposed of. Biocides are not required because of the elevated
Fig. 7. Treatment technologies for produced water, including minimal treatment of PW for hydraulic fracturing (clean brine), desalination for benecial uses in various sectors, surface
water discharge and groundwater recharge, and posttreatme nt technologies. TDS: total diss olved solids; ED : electrodialysis; NF: Nanoltration; BWRO: brackish water reverse
osmosis; SWRO: seawater reverse osmosis; MED: multiple effect distillation; MVC: mechanical vapor compression; MVR: mechanical vapor recompression, emerging technologies
including FO: Forward Osmosis; MD: membrane distillation. AOP: advanced oxidation processes.
9B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
temperature. MVR has been applied to waters with up to 300 g/L TDS
and can generate high quality water (Nasiri et al., 2017). MVR can be
used as a crystallizer for systems with zero liquid discharge (ZLD). How-
ever, managing solids is often challenging; therefore, systems designed
to generate a concentrated brine are often preferred (GWPC, 2019).
Thermal approaches have high energy requirements and are generally
used where waste heat is available.
In addition, emerging technologies are being developed to improve
certain aspects of the performance of existing desalination processes
(e.g., increasing recoveries, reducing fouling, decreasing energy con-
sumption and capital and operating costs). These new technologies
can be classied into three categories: thermal (membrane distillation,
MD), physical (forward osmosis, FO), and chemical (capacitive deioni-
zation). MD uses a heat source to enhance mass transport through
membranes. One of the advantages of this approach is its ability to use
any level of TDS in the feed solution. Solutes, including Na, SiO
heavy metals, are rejected at nearly 100%. Water recovery can be im-
proved when paired with crystallizer technologies. A research example
based on treating PW with ~250 g/L TDS showed this approach to be
cost competitive (Macedonio et al., 2014). Forward osmosis is an os-
motic pressure driven membrane process (Hickenbottom et al., 2013;
Xu et al., 2013). Water diffuses from a feed stream with low osmotic
pressure through a semi-permeable membrane to a draw solution
with high osmotic pressure. No external high pressure is required by
an FO system. Other hybrid congurations are also being developed by
different companies, such as the Veolia OPUSsystem. Development
of cost-effective desalination technologies represents the new frontier
of PW treatment research. Although these emerging technologies have
shown promise in highly saline PW treatment, improvements in mem-
brane properties, membrane design, and module hydrodynamics are
expected to further increase system efciency (Shaffer et al., 2013).
A limited number of treatment plants have been developed for PW.
Antero Resources built a large desalination plant (Antero Clearwater Fa-
cility) in the Marcellus to treat up to 10 million liters of PW/day (GWPC,
2019). The estimated cost was ~$300 million; however, the facility was
recently closed for evaluation. Eureka Resources developed three central-
ized wastewater treatment facilities to generate water t for discharge
from PW in the Marcellus (Mueller, 2017). Treatments include mechani-
cal vapor recompression distillation and crystallization. ALL Consulting
provided a treatment technology tool that includes treatment types and
vendors for specic basins: Marcellus, Fayetteville, Haynesville,
Woodford, and Barnett; however, the information is generally applicable
to other basins (
Besides salts, PW and owback water contain complex organic con-
stituents such as oil and grease, BTEX (benzene, toluene, ethylbenzene
and xylene), PAHs (polycyclic aromatic hydrocarbons), biopolymers,
and humic substances (Danforth et al., 2020;Khan et al., 2016). These
organic constituents in high salinity water present unique challenges
to most technologies. Organic matter must be removed rst to minimiz e
fouling of membranes or other surfaces, and to prevent environmental
impacts during disposal or reuse. Biological processes have been suc-
cessfully used to remediate water contaminated by petroleum hydro-
carbons, solvents, and other dissolved organic chemicals commonly
observedin PW. The effectiveness of biological processes varies depend-
ing on the properties of chemicals present and their respective concen-
trations, as well as the salinity level in PW. For example, organic
compounds such as BTEX and PAHs are readily biodegradable in aerobic
processes, whereas halogenated organic compounds or highly chlori-
nated compounds are more refractory. Physico-chemical treatment,
such as adsorption and advanced oxidationprocesses, can be used to re-
move organic contaminants. Because the treatment technologies may
not be highly effective in removing contaminants, risk assessment
should also be conducted on the treated PW to evaluate the impact of
PW reuse on public health and environment.
Limited information on concentrate management indicates that PW
is often treated to a point where the residual is still sufciently liquid to
be injected into a SWD well. The low recoveries of thermal distillation
techniques result in up to 80% concentrate that is generally injected
into SWD wells. In some cases, the concentrate is solid (ZLD) and the
products are either marketed (salts) or disposed of in landlls (Ertel
and Bogdan, 2017). For example, PW from the Delaware Basin in 2017
(160 BL, 43 Bgal) would result in 16 × 10
kg of salt, or 16 million
tons assuming a TDS of ~100 g/L (SI, Section 3). This would correspond
to a volume of solids approximating ~3000 Olympic swimming pools.
Disposal of solid wastes laden with contaminants transferred and con-
centrated from PW may becost prohibitive and may not be a viable op-
tion to reach ZLD or high water recovery for PW treatment.
4.2. Implications for produced water management
There is considerable interest in benecially using PW outside of the
energy sector because of the perception that PW represents huge water
volumes and reuse would retain the water within the hydrologic cycle,
whereas subsurface disposal removes it from the active hydrologic
cycle. The total volume of PW from UOG reservoirs in 2017 (~600 BL,
~160 Bgal) corresponds to ~60% of fresh water use in the U.S. in one
day, excluding thermoelectric water use. However, most of the PW is
generated in semiarid regions where water scarcity is a big concern. In
gas plays (Haynesville, Marcellus) and some oil plays (Eagle Ford, Nio-
brara, and Permian Midland), HF water demand exceeds PW volumes;
therefore, much of this PW could be reused within the energy sector
and reduce water scarcity caused by pumping water to supply HF.
Reuse within the energy sector represents much less risk with minimal
treatmentand related lower costs and energy usethan benecial use of
PW in other sectors.
The most likely sector to reuse PW in semiarid western U.S. is irriga-
tion. Irrigation exceeds PW volumes in many plays, except the Okla-
homa AOI, Barnett play, and Permian Delaware Basin. If we assume
that PW is rst reused within the energy sector, only half of the plays
would have excess PW relative to HF water demand. Considering
water treatment requirements and recovery factors would further re-
duce the PW volumes. PW as a percent of irrigation would represent
2% of irrigation in the Bakken, 5% in the Permian Delaware Basin, 63%
in the Barnett, and 77% in Oklahoma AOI, assuming 50% recovery factors
for treatment. The percentages are more variable at the county scale,
showing counties with largepotentialin the Oklahoma AOI and Barnett.
Some point to examples in California where PW is reused for irrigation;
however, the water quality is quite high and treatment is minimal (SI,
Section 4). Other sectoral uses represent more localized demands,
such as municipal and industrial uses. Detailed site specic studies
would be required before discharging PWto surface water or recharging
groundwater would be considered. Therefore, it does not seem that PW
reuse will mitigate water scarcity concerns in mostregions. Water scar-
city related to oil and gas development would be more readily ad-
dressed by reusing PW within the energy sector in different plays.
Development of treatment plants for benecial reuse of PW would
require a reliable feedstock. Maintaining PW volumes requires contin-
ued drilling because of exponential declines in PW volumes with time
from UOG and CBM plays (Fig. 8).
Many factors currently do not support reuse of PW outside of theen-
ergy sector. From a volumetric perspective, reuse of PW within the en-
ergy sector would eliminate half of the plays because HF water demand
exceeds PW in these plays. In the remaining plays, PW represents a
small fraction of water demand for irrigation mostly at the play and
county level. In the future, high projected PW volumes in the Permian
Delaware Basin, exceeding projected HF water demand, would support
PW reuse outside of energy in future decades. From a water quality per-
spective, the following limitations restrict the potential for PW reuse
outside of energy: poor knowledge of PW chemistry, inability to accu-
rately measure the PW quality because ofhigh salinity matrix and inter-
ference issues, lack of acceptable measurement techniques, absence of
suitablestandards, and lack of regulations for various sectors to consider
10 B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
the complexity of PW. In addition, suitable treatment technologies, such
as thermal distillation, are expensive and have high energy demands.
The efciency of different treatment technologies in removing certain
contaminants, particularly those with a boiling point similar to water,
for example, is also not known. Because of these many uncertainties,
more emphasis is placed on risk assessment, whole efuent toxicity,
and related factors. The risks and liabilities associated with PW reuse
outside the energy sector are high, and much more data are required
to address uncertainties in this eld before such reuse should be
5. Conclusions
Although interest in benecially reusing the large volumes of PW
generated from UOG reservoirs is increasing in the U.S., quantitative
analysis of the volumetric and water quality issues does not support
reuse outside of the energy sector.
PW volumes in 2017 totaled ~600 BL (160 Bgal) from UOG reser-
voirs, primarily from tight oil reservoirs in the semiarid western U.S.,
and ~45 BL (12 Bgal) from CBM reservoirs. Benecial reuse outside of
the energy sector would favor irrigation, the largest water user. Irriga-
tion exceeds PW from UOG reservoirs by ~5× and PW from CBM reser-
voirs by ~50×. Reuse of PW for HF water demand within the energy
sector would reduce the number of UOG plays with excess PW by
about half. PW requires intensive treatment for reuse outside of energy.
If we assume an average recovery factor from treatment of ~50%, then
the ratio of irrigation to PW would be doubled. Considering all of
these factors, plays with potential for PW reuse for irrigation include
Oklahoma AOI, Barnett, and the Permian Delaware Basin. PW volumes
in the Permian Delaware Basin would represent ~5% of the irrigation de-
mand. PW projections relative to HF water demand would double in the
Permian over the life of the play. Other sectoral users may provide local
potential for reuse, including municipal, livestock and industrial uses
but are generally limited based on volumetric analysis. Discharging
PW to surface water is also being considered, but the PW would not
be substantially diluted in western streams. Recharging depleted aqui-
fers is also aconsideration; however, water quality issues may preclude
this option.
VariableTDS of PW from UOG reservoirs (median TDS: 244 g/L inthe
Bakken, up to 7× seawater), would mostly require thermal distillation
approaches to treat the PW. PW from CBM reservoirs is much higher
quality (median TDS: 111 g/L) and does not include HF water. Evalua-
tion of PW from CBM plays provides an example of PW that can be con-
sidered for potential reuse outside the energy sector. It is difcult to
characterize the PW quality from UOG reservoirs because of problems
with measurements, interferences caused by the high salinity matrix,
and lack of suitable standards resulting in many unknowns. Uncer-
tainties in treatment efciency and problems with contaminants
leaking through the treatment process further increase risks of reuse.
The current regulations for various sectoral uses and discharge require-
ments were not designed to address PW issues. Therefore, large uncer-
tainties related to water quality issues currently preclude PW reuse
outside of the energy sector.
In summary, water scarcity issues are more readily addressed by
reusing PW within the energy sector rather than benecial use of PW
outside of the energy sector. Much more research is required to safely
reuse PW in other sectors or discharge to surface waters or recharge
Declaration of competing interest
The authors declare that they have no known competing nancial
interests or personal relationships that could have appeared to inu-
ence the work reported in this paper.
We are very grateful for nancial support for this study from the
MitchellFoundation, Sloan Foundation, ExxonMobil, and Jackson School
of Geosciences Endowment. We very much appreciate access to the IHS
Enerdeq database.
Appendix A. Supplemenary data and Information
Raw data on water volumes and water quality used in this study are
archived in Mendeley Data (10.17632/jjy5mtfkfk.2) and described in an
associated data article (Scanlon et al., submitted). Supplementary data
to this article can be found online at
scitotenv.2020.137085. Additional gures and tabulated data are pro-
vided in the Supporting Information.
ALL, 2010. Water Treatment Technology Fact Sheet: Reverse Osmosis. ALL Consulting.
Arthur, J.D., Langhus, B.G., P., C., 2005. Technical summary of oil & gas produced water
treatment technologies. Report Prepared by ALL Consulting for the National Energy
Technology Lab. (NETL) and the Dept. of Energy (DOE).
Barnes, C.M., Marshall, R., Mason, J., Skodack, D., DeFosse, G., Smigh, D.G., et al., 2015. The
New Reality of Hydraulic Fracturing: Treating Produced Water is Cheaper thanUsing
Fresh. SPE-174956-MS. Society of Petroleum Engineering 29 p.
Blondes, M.S., Gans, K.D., Engle, M.A., Kharaka, Y.F., Reidy, M.E., Sarraswathula, V., et al.,
2017. U.S. Geological Survey National Produced Waters Geochemical Database v2.3
(Provisional) . https://ene /EnvironmentalAspects/
Brinck, E.L., Drever, J.I., Frost, C.D., 2008. The geochemical evolution of water coproduced
with coalbed natural gas in the Powder River Basin, Wyoming. Environ. Geosci. 15,
Chaudhary, B.K., Sabie, R., Engle, M.A., Xu, P., Willman, S., Carroll, K.C., 2019. Spatial vari-
ability ofproduced-water quality and alternative-source wateranalysis applied to the
Permian Basin, USA. Hydrogeol. J. 27, 28892905.
Clark, C., Veil, J., 2009. Produced water volumes and management practices in the United
States. Rep. ANL/EVS/R-09/1, Argonne Natl. Lab., Argonne, Ill.
Danforth, C., McPartland, J., Blotevogel, J., Coleman, N., Devlin, D., Olsgard, M., et al., 2019.
Alternative management of oil andgas produced water requires more research onits
hazards and risks. Integr. Environ. Assess. Manag. 15, 677682.
Danforth, C., Chiu, W.A., Rusyn, I., Schultz, K., Bolden, A., Kwiatkowski, C., et al., 2020. An
integrative method for identication and prioritization of constituents of concern in
produced water from onshore oil and gas extraction. Environment Intl 134, 677682.
Fig. 8. Produced water decline curves for the major tight oil (T O: Bakken, Midland,
Delaware), shale gas (SG: Marcellus), mixed TO and SG, (Eagle Ford) plays and for the
Powder River Basin coal bed methane play (PRB). Data represent the median monthly
produced water volumes expressed as a percentage of rst-month production for wells
completed during 20152017, except the PRB (19892018), in which few wells produce
longerthan 10 years. Note that theDelaware and Marcellusdeclines are virtually identical.
11B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
Dieter, C.A., Maupin, M.A., Caldwell, R.R., Harris, M.A., Ivahnenko, T.I., Lovelace, J.K., et al.,
2018. Estimated Use of Water in the United States in 2015. 1441. U.S. Geological Sur-
vey Circu lar 65 p.
Dolan, F.C., Cath, T.Y., Hogue, T.S., 2018. Assessing the feasibility of using produced water
for irrigation in Colorado. Sci. Total Environ. 640, 619628.
Engle, M.A., Reyes, F.R., Varonka, M.S., Orem, W.H., Ma, L., Lanno, A.J., et al., 2016. Geo-
chemistry of formation waters from the Wolfcamp and Clineshales: insights into
brine origin, reservoir connectivity, and uid ow in the Permian Basin, USA. Chem.
Geol. 425, 7692.
Ertel, D.J., Bogdan, J.J., 2017. A Sustainable Choice for Unconventional Oil and Gas Waste-
water Management/Treatment When Options are Limited (EM, August RO).
Ferguson,G., McIntosh, J.C.,Perrone, D., Jasechko, S., 2018.Competition for shrinking win-
dow of low salinity groundwater. Environ. Res. Lett. 13.
Graham, E.J.S., Jakle,A.C., Martin, F.D.,2015. Reuse of oil and gasproduced water in south-
eastern New Mexico: resource assessment, treatment processes, and policy. Water
Int. 40, 809823.
Greaves, R., Hartstein, R., Lincicome, D., Beck, P., Boothe,M., Olson, K.E., 2017. Fresh water
neutral: managing water use and giving back to the environment. SPE Annual Tech-
nical Conference and Exhibition. Society of Petroleum Engineers, San Antonio, Texas,
USA, p. 27.
Guerra,K., Dahm, K., Dundorf,S., 2011. Oil and gas produced water management and ben-
ecial use in the western United States. Bureau of Reclamation Science and Technol-
ogy Report No. 157 113 p.
GWPC, 2019. Prod uced Water Report: Regulations, Current Practices, and Research
Needs. Groundwater Protection Council (GWPC) 310 p.
Hanor, J.S., 199 4. Origin of saline uids in sedime ntary basins. In: Parnell, J. (Ed.),
Geouids: Origin, Migration and Evolution of Fluids in Sedimentary Basins. 78. Geo-
logical Society Special Publications, pp. 151178.
Hayden, M., 2017. Local potash dipping toes into water business. Carlsbad Current Argus,
June 16, 2017.
Healy, R.W., Bartos, T.T., Rice, C.A., McKinley, M.P., Smith, B.D., 2011. Groundwater chem-
istry near an impoundment for produced water, Powder River Basin,Wyoming, USA.
J. Hydrol. 403, 3748.
Hickenbottom, K.L., Hancock, N.T., Hutchings, N.R., Appleton, E.W., Beaudry, E.G., Xu, P., et
al., 2013. Forward osmosis treatment of drilling mud and fracturing wastewater from
oil and gas operations. Desalination 312, 6066.
Horner, R.M., Harto, C.B., Jackson, R.B., Lowry, E.R., Brandt, A.R., Yeskoo, T.W., et al., 2016.
Water use and management in the Bakken Shale oil play in North Dakota. Environ-
mental Science & Technology 50, 32753282.
Huang, Y., Scanlon, B.R., Nicot, J.P., Reedy, R.C., Dutto n, A.R., Kelley, V. A., et al., 2012.
Sources of groun dwater pumpage in a layered aquifer system in th e Upper Gulf
Coastal Plain, USA. Hydrogeol. J. 20, 783796.
Igunnu, E.T., Chen, G.Z., 2014. Produced water treatment technologies. J. Low Carbon
Technol. 9, 157177.
Khan, N.A., Engle, M., Dungan, B., Holguin, F.O., Xu, P., Carroll, K.C., 2016. Volatile-organic
molecular characterization of sh ale-oil prod uced water from the Permian Basin.
Chemosphere 148, 126136.
Kondash, A.J., Albright, E., Vengosh, A., 2017. Quantity of owback and produced waters
from unconventional oil and gas exploration. Sci. Total Environ. 574, 314321.
Kurz, B.A.,Stepan, D.J., Glazewski, K.A.,Stevens, B.G., Döll, T.E., Kovacevich, J.T.,et al., 2016.
A review of Bakken water management practices and potential outlook. Final Con-
tract Rept. Prepared for the Members of the Bakken Production Optimization Pro-
gram. Univ. of N. Dakota Energy adn Environmental Research Center 42 p.
Landis, M.S., Kamal, A.S., Kovalcik, K.D., Croghan, C., Norris, G.A., Bergdale, A., 2016. The
impact of commercially treated oil and gas produced water discharges on bromide
concentrations and modeled brominated trihalomethane disinfection byproducts at
two downstream municipal drinking water plants in the upper Allegheny River,
Pennsylvania, USA. Sci. Total Environ. 542, 505520.
Lauer, N.E., Harkness, J.S., Vengosh, A., 2016. Brine spills associated with unconventional
oil development in North Dakota . Environment al Science & Technology 50,
Lemons, C.,McDuid, G., Smye, K.M., Acevedo, J.P., Hennings, P.H., Banerji, D.A., et al.,2019.
Spatiotemporal and stratigraphic trends in salt-water disposal practices of the Perm-
ian Basin, Texas and New Mexico, United States. Env. Geosciences 26 (4), 107124.
Luek, J.L.,Gonsior, M., 2017. Organic compounds in hydraulic fracturing uids and waste-
waters: a review. Water Res. 123, 536548.
Macedonio, F., Ali, A., Poerio, T., El-Sayed, E., Drioli, E., Abdel-Jawad, M., 2014. Direct con-
tact membrane distillation for treatment of o ileldproducedwater.Sep.Purif.
Technol. 126, 6981.
McMahon, B., Mackay, B., Mirakyan, A., 2015. First 100% reuse of Bakken produced water
in hybrid treatments using inexpensive polysaccharide gelling agents. Society of Pe-
troleum Eng ineers, SPE-173783-MS. Society of Petroleum Eng ineers .
Meng, Q.M., 2017. The impacts of fracking on the environment: a total environmental
study paradigm. Sci. Total Environ. 580, 953957.
Mueller, D., 2017. Water Management Associated With Oil and Gas Development and
Production. EM, August 2017. .
NASEM, 2010. Management and Effectsof Coalbed Methane Produced Water in the West-
ern United States. National Acade mies of Sciences, Engineering, and Medicine
(NASEM), National Acadmey Press., Washington DC.
Nasiri, M., Jafari, I., Parniankhoy, B., 2017. Oil and gas produced water management: a re-
view of treatment technologies, challenges, and opportunities. Chem. Eng. Commun.
204, 9901005.
Nelson, A.W., May, D., Knight, A.W., Eitrheim, E.S., Mehrhoff, M., Shannon, R., et al., 2014.
Matrix complications in the determination of radium levels in hydraulic fracturing
owback water from Marcellus Shale. Environmental Science & Technology Letters
1, 204208.
Nichols, K., Sawyer, J., Bruening, J., Halldorson, B., Madhavan, K., 2017. Development of a
large scalewater recycling program for the Delaware Basin, New Mexico.Soc. of Pet-
rol. Engin., SPE-186086-MS 12 p.
Nicot, J.P., Scanlon, B.R., Reedy, R.C., Costley, R.A., 2014. Source and fate of hydraulic frac-
turing water in the Barnett shale: a historical perspective. Environmental Science &
Technology 48, 24642471.
Nicot, J.P., Gher abati, A., Darvari, R., Mickler, P., 2018. Salinity r eversal and water
freshening in the Eagle Ford Shale, Texas, USA. ACS Earth and Space Chemistry 2,
NRC, 2009. Science and Decisions: Advancing Risk Assessment.National ResearchCouncil,
National Acadmey Press, Washington DC, p. 422.
Oetjen, K., Giddings, C.G.S., McLaughlin, M., Nell, M., Blotevogel, J., Helbling, D.E., et al.,
2017. Emerging analytical methods for the characterization and quantication of or-
ganic contaminants in owback and produced water. Trends in Environmental Ana-
lytical Chemistry 15, 1223.
Orem, W., Tatu, C., Varonka, M., Lerch, H., Bates, A., Engle, M., et al., 2014. Organic sub-
stances inproduced and formation water from unconventional natural gas extraction
in coal and shale. Int. J. Coal Geol. 126, 2031.
Pashin, J.C., McIntyre-Redden, M.R., Mann, S.D., Kopaska-Merkel, D.C., Varonka, M.,Orem,
W., 2014. Relationships between water and gas chemistry in mature coalbed meth-
ane reservoirs of the Black Warrior Basin. Int. J. Coal Geol. 126, 92105.
Phan, T.T., Capo, R.C., Stewart, B.W., Macpherson, G.L., Rowan, E.L.,Hammack, R.W., 2016.
Factors controlling Li concentration and isotopic composition in formation waters
and host rocks of Marcellus Shale, Appalachian Basin. Chem. Geol. 420, 162179.
Rassenfoss, S., 2011. From owback to fracturing: water recycling grows in the Marcellus
Shale. SPE Journal of Petroleum Technology 63 (7), 4851.
Reig, P., Luo, T., Proctor, J.N., 2014. Global Shale Gas Development: Water Availability and
Business Risks. World Resources Institute Jan 2013, 80 p.
Rowan, E.L., Engle, M.A., Kraemer, T.F., Schroeder, K.T., Hammack, R.W., Doughten, M.W.,
2015. Geochemical and isotopic evolution of water produced from Middle Devonian
Marcellus shale gas wells, Appalachian basin, Pennsylvania. AAPG Bull. 99, 181206.
Scanlon, B.R., Faunt, C.C., Longuevergne, L., Reedy, R.C., Alley, W.M., McGuire, V.L., et al.,
2012. Groundwater depletion and sustainability of irrigation in the US High Plains
and Central Valley. Proc. of Natl. Acad. of Sciences 109, 93209325.
Scanlon, B.R., Reedy, R.C., Male, F., Hove, M., 2016. Managing the increasing water foot-
print of hydraulic fracturing in the BakkenPlay, United States.Environmental Science
& Technology 50, 1027310281.
Scanlon, B.R., Reedy, R.C., Male, F., Walsh, M., 2017. Water issues related to transitioning
from conventional to unconventional oil production in the Permian Basin. Environ-
mental Science & Technology 51, 1090310912.
Scanlon,B.R., Weingarten,M.B., Murray, K.E.,Reedy, R.C., 2019.Managing basin-scale uid
budgets to reduce injection-induced seismicity from the recent U.S. shale oil revolu-
tion. Seismol. Res. Lett. 90, 171182.
Scanlon,B.R., Ikonnikova,S., Yang, Q., Reedy, R.C., 2020. Will water issues constrain oil and
gas production in the U.S.? Env. Science and Technol.
Scanlon, B.R., Reedy, R.C., Xu, P., Engle, M., Nicot, J.P., Yoxtheimer, D., et al., 2020. Datasets
Associated With Investigating the Potential for Benecial Reuse of Produced Water
From Oil and Gas Extraction Outside of the Energy Sector (Data in Brief submitted).
Shaffer, D.L., Arias Chavez, L.H., Ben-Sasson, M., Romero-Vargas Castrillon, S., Yip, N.Y.,
Elimelech, M., 20 13. Desalination and reuse of high-salinity shale gas produced
water: drivers, technologies, and future directions. Environ Sci Techno l 47,
Shuh WM. Water Appropriation Requirements, Current Water Use, & Water Availability
for Energy Industries in North DakotaA 2010 Summary: Response to House Bill
1322, Section 2 of the 61st Legislative Assembly of NorthDakota, Water Resources In-
vestigation No. 49, North Dakota State Water Commission, August 2010, www.swc. W&E%20RPT%20FinalR.pdf
(accessed 2014). 2010.
Stewart, B.W., Chapman, E.C., Capo, R.C., Johnson, J.D., Graney, J.R., Kirby, C.S., et al., 2015.
Origin of brines, salts and carbonate from shales of the Marcellus Formation: evi-
dence from geochemical and Sr isotope study of sequentially extracted uids. Appl.
Geochem. 60, 7888.
Tasker, T.L., Burgos, W.D., Ajemigbitse, M.A., Lauer, N.E., Gusa, A.V., Kuatbek, M., et al.,
2019. Accuracy of methods for reporting inorganic element conce ntrations and
radioactivity in oil and gas wastewaters from the Appalachian Basin, US based on
an inter-laboratory comparison. Environmental Sci ence-Processes & Impacts 21,
Torres, L., Yadav, O.P., Khan, E., 2016. A review on risk assessment techniques for hydrau-
lic fracturing water and produced water management implemented in onshore un-
conventional oil and gas production. Sci. Total Environ. 539, 478493.
USEPA. EPA signs MOU with New Mexico to explore wastewater reuse options in oil and nat-
ural gas industry. [accessed 2018 Jul 30]. 2018.
Veil, J., 2015. U.S. produced water volumes and management practices in 2012. Report
Prepared for the Groundwater Protection Council, April 2015.
Walker, E.L.,Anderson, A.M., Read, L.K., Hogue, T.S.,2017. Water use for hydraul ic fractur-
ing of oil and gas in theSouth Platte River Basin, Colorado. J. Am.Water Resour. Assoc.
53, 839853.
Walsh, F.R., Zoback, M.D., 2015. Oklahomas recent earthquakes and saltwater disposal.
Sci. Adv. 1.
Xu, P., Cath, T.Y., Robertson, A.P., Reinhard, M., Leckie, J.O., Drewes, J.E., 2013. Critical re-
view of desalination concentratemanagement, treatment and benecial use. Environ.
Eng. Sci. 30.
12 B.R. Scanlon et al. / Science of the Total Environment 717 (2020) 137085
... Basin (Scanlon et al., 2020b). ...
... One of the barriers to using treated PW as an alternative water source is the lack of comprehensive characterization of PW quality (Scanlon et al., 2020b). To date, most studies devoted to PW characterization are focused on the Appalachian Basin (Danforth et al., 2020). ...
... Cl (Hanor, 1994), and that PW from the tight O&G plays is dominated by Na (median: 15,000 -76,000 mg/L) and Cl (median: 22,000 -150,000 mg/L) (Scanlon et al., 2020b). The median TDS in the Permian Basin (122,000 mg/L) is lower than in the Bakken tight oil (244,000 mg/L) and ...
Technical Report
Full-text available
The rapid development of the unconventional oil and gas industry has promoted economic growth in the southwestern region of the United States. One of the major barriers for using treated produced water as an alternative water source is the lack of a comprehensive assessment of produced water quality and environmental toxicity. In this study, we employed advanced analytical methods to measure more than 300 targeted analytes including inorganics (e.g., salts, major ions, and metals), organics (e.g., total organic carbon, volatile and semi-volatile organic contaminants), and radionuclides in produced water. In vitro assays were developed as valuable tools for the toxicity assessment of produced water. Overall, an understanding of the physicochemical and toxicological properties of produced water is critical for establishing management practices, proper risk assessment, spill response, treatment, and beneficial use applications.
... Although the concentrations of individual organic compounds are generally low in CBMPW (< 10 g/L, Orem et al. 2014), they can be highly toxic at low concentrations (Scanlon et al. 2020), and the consequences of long-term, low-level (chronic) exposures are not wellknown (Orem et al. 2014). In fact, most of the organic chemicals found in CBMPW (as per Orem et al. 2014) are classified as hazardous to aquatic life (United Nations 2019; European Chemicals Agency 2021). ...
... Treatment of produced water for fit-for-purpose will encounter the same data gaps as regulation has (see 1-7 in Regulatory Framework and Limitations section), among other challenges (Scanlon et al. 2020). States. ...
Full-text available
Coalbed methane (CBM) is a type of natural gas produced from coal beds, and its extraction brings massive quantities of water from coal formations to the surface. CBM produced water is elevated in salinity and sodicity and can also contain heavy metals, trace elements, and organic compounds, all of which can be harmful to aquatic life. Discharge of produced water directly into streams is permitted in some CBM basins and has been occurring in the semi-arid Raton Basin of southern Colorado since the 1990s. Field studies assessing the impacts of this type of discharge on stream ecosystems have been few and have yielded equivocal results, and none have been conducted in the Raton Basin. The effects of the surface discharge of CBM produced water on the health of small headwater streams in a 30,000-acre State Wildlife Area in the Purgatoire River watershed of Las Animas County, Colorado were studied. Ten contaminated streams (below discharge points) and six comparable reference streams (having no discharge) were sampled and analyzed for differences in macroinvertebrate community structure and water quality. Non-metric multidimensional scaling ordinations showed significant separation in both water quality and community structure between the two stream types. Based on their concentrations and published regulatory/safe levels, the water quality parameters of concern in the produced water streams were determined to be: alkalinity, conductivity, chloride, pH, fluoride, aluminum, iron, temperature, dissolved oxygen, ammonia, and the sodium adsorption ratio (SAR). Reduced calcium and magnesium were also of concern. The biodiversity metrics Taxa Richness, EPT Richness, and Shannon-Wiener Diversity were all significantly lower in the produced water streams than the natural streams. Also, the Top 5 Taxa Percent was significantly higher, indicating lower diversity due to unevenness. The Colorado Macroinvertebrate Multimetric Index (MMI) did not differ between the two stream types, however. Stoneflies and oligochaetes were significantly reduced in both taxa richness and relative abundance in the produced water streams. Mayflies and caddisflies showed significantly decreased richness but unchanged relative abundance levels, due to certain tolerant taxa proliferating in the produced water streams. The variables showing the strongest correlation to biodiversity and community composition were calcium, SAR, and magnesium, with calcium appearing to have a protective effect on the communities. Though CBM produced water may not be as deleterious to aquatic life as other oil and gas produced waters, and although it is not regulated by EPA effluent guidelines, the present study shows that CBM produced water discharge can have significant and possibly long-lasting effects on small intermittent/ephemeral receiving streams.
... Recently petroleum source rocks (shales), which have traditionally been considered as a source of oil and gas converted from solid organic matter called kerogen in them, were found to be a potentially sustainable source of Li, given the high concentrations of Li (80-300 ppm) in water produced from the shale reservoirs and the wide distribution of the shale plays across the U. S. [5][6][7]. Given that total volume of produced water from Marcellus Shale is projected to be about 2,200 × 10 9 L for upcoming 73 years [8], produced water from Marcellus Shale is expected to provide the significant potential of Li recovery. Not only from Marcellus Shale, but from its entire shale plays, U.S. daily produces about 2.8 billion gallons of produced water [9]. ...
In order to mitigate climate change, diversifying the sources of lithium supply is crucial for the decarbonization of energy sector through enhanced renewable electricity generation and electrified transportation. Shale brines have been recently found to be containing significant amount of lithium, but relevant subsurface phenomena regarding its origin, fate, and transport are unknown. Here we present a suite of geochemical experiments to elucidate the initial presence of lithium in shale rocks and its release mechanism from solid phase into fluid, and numerical modeling to estimate the resources of lithium in shale brines by addressing its fate and transport. We find that the majority of lithium is inorganically bound as an interlayer cation of clay in shale rock, while a sparingly small portion is organically bound. Hydrothermal reaction experiments for leaching lithium reveal that calcium ion in fluid has strongest impact on lithium to be released into fluid, while sodium ion has minimal impact. From the numerical modeling combined with the experimental findings, average concentration of lithium in shale brines mimicking Marcellus Shale system is estimated to be about 135 ppm under calcium ion dominancy in pore fluid, which shows excellent match with actually measured values from produced Marcellus Shale brines. This study provides the understanding of fundamental phenomena addressing release, transport, and accumulation of lithium in geologic system, and hence contributes to the enhancement of sources of lithium supply for energy decarbonization.
... Therefore, it is important to carry out further studies on the treatment and recycling of generated water from oil fields. In addition to its significant environmental impacts, this process can help in recycling water resources, certain crude oil resources, and produce some economic advantages (Munirasu et al., 2016;Scanlon et al., 2020). Hence, it is critically necessary to develop a new technique for the effective treatment of oilfield generated water. ...
... The oilfield's geographic location, technique of extraction, hydrocarbon products being extracted, as well as minerals available within the geologic formation have impacts on the chemical and physical characteristics of OPW. The water typically has the chemical features of the hydrocarbons present in the OPW since they have had physico-chemical interactions for many years with hydrocarbon-bearing formations (Scanlon et al., 2020). The average OPW is saline and contains significant levels of TDS as well as magnesium, sulfate, sodium, calcium, and chloride. ...
Risk and resilience assessments for critical infrastructure focus on myriad objectives, from natural hazard evaluations to optimizing investments. Although research has started to characterize externalities associated with current or possible future states, incorporation of equity priorities at project inception is increasingly being recognized as critical for planning related activities. However, there is no standard methodology that guides development of equity‐informed quantitative approaches for infrastructure planning activities. To address this gap, we introduce a logic model that can be tailored to capture nuances about specific geographies and community priorities, effectively incorporating them into different mathematical approaches for quantitative risk assessments. Specifically, the logic model uses a graded, iterative approach to clarify specific equity objectives as well as inform the development of equations being used to support analysis. We demonstrate the utility of this framework using case studies spanning aviation fuel, produced water, and microgrid electricity infrastructures. For each case study, the use of the logic model helps clarify the ways that local priorities and infrastructure needs are used to drive the types of data and quantitative methodologies used in the respective analyses. The explicit consideration of methodological limitations (e.g., data mismatches) and stakeholder engagements serves to increase the transparency of the associated findings as well as effectively integrate community nuances (e.g., ownership of assets) into infrastructure assessments. Such integration will become increasingly important to ensure that planning activities (which occur throughout the lifecycle of the infrastructure projects) lead to long‐lasting solutions to meet both energy and sustainable development goals for communities.
Conference Paper
Scale prevention is one of the most important problems in the oil and gas industry. Due to the more aggressive production behavior recently, there are more chances to encounter high temperature, high pressure, and high TDS conditions. This study focuses on improving the scale prediction in the condition of high temperature (up to 210°C), and TDS (total dissolved solids, over 300,000 mg/L) with calcium concentration up to 2.0 molality (m). A hydrothermal autoclave reactor was developed for solubility measurement. The solubility of anhydrite was measured in the CaCl2-NaCl-H2O solution with constant ionic strength of 4 m. Results shows that the ionic strength effect and the Ca-SO4 association would increase the anhydrite solubility while the common ion effect decreased the anhydrite solubility. The measured solubility data can develop the virial coefficient for the ion interaction of Ca2+ and SO42. This virial coefficient can then be applied in Pitzer models to improve the calculation for the saturation index of scale. Quantifying the Ca-SO4 interaction parameters can make a better prediction of mineral solubility with high calcium concentration. The results can also improve not only anhydrite but all of the sulfate scale predictions at high temperature with high TDS conditions. This study offers a reliable and efficient method to obtain solubility under high temperature conditions and expands the scale prediction of the production brine with high calcium concentration at higher temperature and pressure limits.
Full-text available
The data in this report are associated with and include data on water volumes and water quality related to the major unconventional oil and gas plays in the U.S.. The data include volumes of water co-produced with oil and gas production, county-level estimates of annual water use volumes by various sectors, including hydraulic fracturing water use, and the quality of produced water. The data on volumes of produced water and hydraulic fracturing water volumes were obtained from the IHS Enerdeq and FracFocus databases. Water use in other sectors were obtained from the U.S. Geological Survey water use database. Data on produced water quality were obtained from the USGS produced waters database.
Full-text available
Rapid growth in U.S. unconventional oil and gas made energy more available and affordable globally, but brought environmental concerns, especially related to water. We analyzed water-related sustainability of energy extraction focusing on: (a) meeting rapidly rising water demand for hydraulic fracturing (HF), and (b) managing rapidly growing volumes of water co-produced with oil and gas (produced water, PW). We analyzed historical (2009–2017) HF water and PW volumes in ~73,000 wells and projected future water volumes in major U.S. unconventional oil (semiarid regions) and gas (humid regions) plays. Results show a marked increase in HF water use, depleting groundwater in some semiarid regions (e.g. by ≤58 ft [18 m]/yr in Eagle Ford). PW from oil reservoirs (e.g. Permian) is ~15× higher than that from gas reservoirs (Marcellus). Water issues related to both HF water demand and PW supplies may be partially mitigated by closing the loop through reusing PW for HF of new wells. However, projected PW volumes exceed HF water demand in semiarid Bakken (2.1×) and Permian Midland (1.3×) and Delaware (3.7×) oil plays, with the Delaware accounting for ~50% of projected U.S. oil production. Therefore, water issues could constrain future energy production, particularly in semiarid oil plays.
Full-text available
In the United States, onshore oil and gas extraction operations generate an estimated 900 billion gallons of produced water annually, making it the largest waste stream associated with upstream development of petroleum hydrocarbons. Management and disposal practices of produced water vary from deep well injection to reuse of produced water in agricultural settings. However, there is relatively little information with regard to the chemical or toxicological characteristics of produced water. A comprehensive literature review was performed, screening nearly 16,000 published articles, and identifying 129 papers that included data on chemicals detected in produced water. Searches for information on the potential ecotoxicological or mammalian toxicity of these chemicals revealed that the majority (56%) of these compounds have not been a subject of safety evaluation or mechanistic toxicology studies and 86% lack data to be used to complete a risk assessment, which underscores the lack of toxicological information for the majority of chemical constituents in produced water. The objective of this study was to develop a framework to identify potential constituents of concern in produced water, based on available and predicted toxicological hazard data, to prioritize these chemicals for monitoring, treatment, and research. In order to integrate available evidence to address gaps in toxicological hazard on the chemicals in produced water, we have catalogued available information from ecological toxicity studies, toxicity screening databases, and predicted toxicity values. A Toxicological Priority Index (ToxPi) approach was applied to integrate these various data sources. This research will inform stakeholders and decision-makers on the potential hazards in produced water. In addition, this work presents a method to prioritize compounds that, based on hazard and potential exposure, may be considered during various produced water reuse strategies to reduce possible human health risks and environmental impacts.
Full-text available
With the U.S. unconventional oil revolution, adverse impacts from subsurface disposal of coproduced water, such as induced seismicity, have markedly increased, particularly in Oklahoma. Here, we adopt a new, more holistic analysis by linking produced water (PW) volumes, disposal, and seismicity in all major U.S. unconventional oil plays (Bakken, Eagle Ford, and Permian plays, and Oklahoma) and provide guidance for long-term management. Results show that monthly PW injection volumes doubled across the plays since 2009. We show that the shift in PW disposal to nonproducing geologic zones related to low-permeability unconventional reservoirs is a fundamental driver of induced seismicity. We statistically associate seismicity in Oklahoma to (1) PW injection rates, (2) cumulative PW volumes, and (3) proximity to basement with updated data through 2017. The major difference between intensive seismicity in Oklahoma versus low seismicity levels in the Bakken, Eagle Ford, and Permian Basin plays is attributed to proximity to basement with deep injection near basement in Oklahoma relative to shallower injection distant from basement in other plays. Directives to mitigate Oklahoma seismicity are consistent with our findings: reducing (1) PW injection rates and (2) regional injection volumes by 40% relative to the 2014 total in wells near the basement, which resulted in a 70% reduction in the number of M ≥ 3:0 earthquakes in 2017 relative to the 2015 peak seismicity. Understanding linkages between PW management and seismicity allows us to develop a portfolio of strategies to reduce future adverse impacts of PW management, including reuse of PW for hydraulic fracturing in the oil and gas sector.
Full-text available
Groundwater resources are being stressed from the top down and bottom up. Declining water tables and near-surface contamination are driving groundwater users to construct deeper wells in many US aquifer systems. This has been a successful short-term mitigation measure where deep groundwater is fresh and free of contaminants. Nevertheless, vertical salinity profiles are not well-constrained at continental-scales. In many regions, oil and gas activities use pore spaces for energy production and waste disposal. Here we quantify depths that aquifer systems transition from fresh-to-brackish and where oil and gas activities are widespread in sedimentary basins across the United States. Fresh-brackish transitions occur at relatively shallow depths over just a few hundred meters, particularly in eastern US basins. We conclude that fresh groundwater is less abundant in several key US basins than previously thought; therefore drilling deeper wells to access fresh groundwater resources is not feasible extensively across the continent. Our findings illustrate that groundwater stores are being depleted not only by excessive withdrawals, but due to injection, and potentially contamination, from the oil and gas industry in areas of deep fresh and brackish groundwater.
Subsurface disposal of salt water coproduced with oil and gas has become a critical issue in the United States because of linkages with induced seismicity, as seen in Oklahoma and northcentral Texas. Here, we assess the spatiotemporal and stratigraphic variations of salt-water disposal (SWD) volumes in the Permian Basin. The results of this analysis provide critical input into integrated assessments needed for handling of produced water and for emerging concerns, such as induced seismicity. Wellbore architecture, permits, and disposal volumes were compiled, interpreted for disposal intervals and geologic targets, and summarized at formation, subregion, a100-mi² (260-km²) area, and monthly volumes for the years 1978-2016. Geologic targets were interpreted by intersecting the disposal intervals with gridded stratigraphic horizons and by reviewing well logs where available. A total of 30 billion bbl (∼5 trillion L) were disposed into 73 geologic units within 6 subregions via 8201 active SWD wells for 39 yr. Most disposal occurred in the Midland Basin and Central Basin Platform (CBP) over the first 34 yr but shifted jrom the CBP to the Delaware Basin over the last 5 yr (2011-2016) with the expansion of unconventional oil and gas production. Approximately half of the salt water is disposed above the major unconventional reservoirs into Guadalupian-aged formations, raising concerns of overpressuring and interference with production. Operators are exploring deeper SWD targets; however, proximity to crystalline basement poses concerns for high drilling costs and the potential for induced seismicity by reactivation of deep-seated faults. Copyright © 2019. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.
Interest in both environmental impact and potential beneficial uses of produced water (PW) has increased with growth in unconventional oil and gas production, especially in semi-arid regions, e.g. the Permian Basin, the most productive tight-oil region in the USA. Characterization of PW compositional variability is needed to evaluate environmental impact, treatment, and reuse potential. Geochemical variability of PW from Guadalupian (Middle Permian) to Ordovician formations was statistically and geostatistically evaluated in the western half of the Permian Basin (Delaware Basin, Central Basin Platform, and Northwest Shelf) using the US Geological Survey’s Produced Waters Geochemical Database and the New Mexico Water and Infrastructure Data System. Mean total dissolved solids (TDS) of PW increased with depth in the Delaware Basin and Central Basin Platform to the Delaware and Wolfcamp formations (Guadalupian age). Mean TDS decreased with further increases in depth. In contrast, the mean salinity of PW was significantly higher within the shallow, younger formations (largest mean TDS in the Artesia Formation); TDS decreased with depth below Guadalupian age formations in the Northwest Shelf. Kriged contour maps of TDS and major ions illustrated spatial variability across the three geo-structural regions as a function of depth. The occurrence of meteoric waters in upper and deeper formations across the three regions was significant, and was attributed to Laramide Orogeny and Basin and Range extension uplifting and tilting effects and recent water flooding. These results quantify PW composition variability, and suggest that upon treatment, PW would support some uses such as onsite reuse and mining.
Produced water is the largest waste stream associated with oil and gas exploration and production operations. Most produced water generated on‐shore is managed by permitted injection in deep underground wells but alternative disposal options including reuse are increasingly being considered. However, insufficient understanding of the composition and toxicity of produced water imposes significant constraints on effective management of potential short‐term and long‐term risks associated with such alternative uses. As interest builds for management options such as surface discharge, livestock watering, irrigation, and other industrial uses, research is needed to assess produced water hazards and exposures to both humans and the environment. This challenge affords an opportunity to capitalize on emerging risk assessment tools. Innovative and comprehensive approaches to filling data gaps and assessing produced water risks will be imperative. A group of experts from industry, academia, and government were assembled to define research needs to support objective decision‐making on the acceptability, or lack thereof, of produced water disposal alternatives. Presented here are key outcomes from that workshop and recommendations for a research framework to assess toxicity of produced water and associated risks from above ground discharge and reuse options. This article is protected by copyright. All rights reserved.
Effective, considerate shale play water management supports operations and protects the environment. A parameter often overlooked is total dissolved solids (TDS) of produced water from the formation. Knowledge of TDS is important to meet these dual goals. Subsurface TDS typically increases with depth. However, produced-water samples from the Eagle Ford Shale show a strong TDS decrease by a factor of ~10 with increasing well depth (~200,000 ppm at ~2.5 km to 18,000 ppm at ~3.6 km). Water stable isotopes strongly suggest that the low TDS is not due to dilution by meteoric water. Rather, we attribute the change to smectite-to-illite conversion, in which the smectite interlayer water is released into the pore space. Depth, temperature, and other related indicators (source for K, excess silica) support such a mechanism. In addition, water-isotope patterns and 87Sr/86Sr ratios suggest a conversion operating with limited contributions external to the shale. Order-of-magnitude calculations show that the 8% of mixed-layer clay present on average in the Lower Eagle Ford Shale is sufficient to bring formation water TDS to observed levels when some of the resident water is expelled. Understanding that the low salinity is an intrinsic property of the formation water rather than due to short-term mixing allows stakeholders to have a more optimistic outlook on water recycling and on using produced water for other uses (irrigation, municipal).