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ORIGINAL PAPER
Diamond core drilling process using intermittent flushing mode
Xin Cao
1,2
&Anatolii Kozhevnykov
3
&Andrii Dreus
4
&Bao-Chang Liu
1,2
Received: 14 March 2018 /Accepted: 25 January 2019
#Saudi Society for Geosciences 2019
Abstract
Core drilling has been the main method for exploration of solid mineral deposits, also used widely for drilling engineering
geological boreholes, hydrogeological wells, etc. But the efficiency of rock destruction during diamond drilling remains fairly
low, especially in some difficult conditions. The main part of power on bottom-hole is wasted to heat generation. Diamond core
drilling efficiency can be improved by using pulse flushing modes, particularly with pulse drilling fluid supply. A broad
classification for possible drilling methods using pulse drilling fluid supply to the downhole has been presented herein.
Among the wide variety of pulse flushing options, particular attention is paid to intermittent flush drilling with alternated on/
off drilling fluid supply. Proposed technology is characterized by using standard diamond drilling bits and drilling equipment.
Thus, transition to the proposed technology does not require significant technical re-equipment of the process and material costs.
The results of bench drilling tests with intermittent flushing were presented. A criterion for drilling with intermittent flushing was
introduced. Test results had shown that transition to intermittent flushing mode allows considerably improved penetration rate (by
1.18 to 2.2 times). Power on bottom-hole value and intermittency factor will affect drilling efficiency by using intermittent
flushing. It is suggested that directional utilization of frictional heat energy in the bottom-hole used for rock destruction is one of
physical principles that govern improving efficiency of drilling with intermittent flushing. The technology considered allows to
utilize diamond drilling’s latent reserves and can become the key technologies to improvement of efficiency of the diamond core
drilling.
Keywords Diamond drilling .Intermittent flushing .Bench test .Efficiency of drilling .Frictional heat energy
Introduction
Rotationaldrillingwith constant operating parameters is wide-
ly used at the moment in prospecting for mineral deposits. In
the meantime, further improvement of this method requires
new design and technology solutions. Transition to
technologies using pulsed variation of drilling process param-
eters is one of such solutions.
Particularly, the developers of rotational drilling technolo-
gies manifest a keen interest to pulsed well flushing methods
recently. For example, a mud-pulse rotational technology for
drilling deep wells with abnormal formation pressure has been
developed in the US (Kollé and Marvin 1999). An ability to
increase penetration speed by use of intermittent jets for well
flushing has been studied (Wang 2005; Liu et al. 2015).
Results of experimental studies mentioned and numeric
modeling allow assuming that rock destruction is performed
more efficiently due to its weakening by jet mechanical impact
and bottom-hole cavitation. Hydraulic pulse generators used
to form frilling fluid supply mode has been considered (Qu
et al. 2016; Shi et al. 2015).
A positive experience of application of pulsed flushing
during diamond and hard-alloy drilling bits has been obtained
in (Tungusov 2009). Authors have shown that using pulsed
flushing promotes for better rock destruction and improves
well cuttings removal efficiency (Filimonenko 2007;
Gorshkov and Gorelikov 1992).
Editorial handling: Murat Karakus
*Bao-Chang Liu
liubc@jlu.edu.cn
1
College of Construction Engineering, Jilin University,
Changchun 130012, China
2
Key Laboratory of Drilling and Exploitation Technology in Complex
Conditions of Ministry of Land and Resources, Changchun 130000,
China
3
Techniques Prospect of Deposits Department, BNational Mining
University^, Dnipro, Ukraine
4
Fluid Mechanics and Energy & Mass Transfer Department, Oles
Honchar Dnipro National University, Dnipro, Ukraine
Arabian Journal of Geosciences (2019) 12:137
https://doi.org/10.1007/s12517-019-4287-2
It has been shown by Fassahov et al. (Fassahov et al. 2005)
that pulsed flushing allows saving power and resources in oil
field operation. Therefore, using alternating drilling fluid sup-
ply allows boosting rock destruction as well as improving
other drilling process conditions.
Taking into account that diamond drilling is one of the most
common ways of prospecting for solid commercial deposits
((Wang et al. 2015).), research held for its improvement is
considered a very important task.
General characteristic of pulsed flushing
modes
Well drilling using pulsed flushing belongs to pulsed drilling
technologies. Concepts, definitions, and classification of
pulsed drilling technologies were proposed first by A.
Kozhevnykov in investigation report of National Mining
University (former Dnipropetrovsk Mining Institute) accord-
ing to the agreement with National Institute for Exploration
Methods and Technology performed. These results are pre-
sented in the form of a report at BDrilled rock mechanics^
international conference (Kozhevnykov 1992). This issue is
detailed by Kozhevnykov and Filimonenko (Kozhevnykov
and Filimonenko 2010), the brief characteristics of pulsed
drilling technologies are summarized as a chart in Table 1.
According to chart in Table 1, there are three variants of
pulsed flush drilling technology:
–one single-parameter, with only one variable parameter
Q;
–two double-parameter, with two variable drilling param-
eters taken in pairs, Qand nor Qand F;
–one triple-parameter (when all three drilling parameters
are variable at a time, Q,n,andF)
In this way, pulsed flushing can be carried out independent-
ly as well as with other transient parameters. Consideration of
pulsed well flushing leads to four possible ways of its imple-
mentation (see Fig. 1).
The following factors have been introduced to characterize
pulsed well flushing.
Pulse factor k
pulse
, the ratio of fluid feed flow variation ΔQ
to max fluid feed flow Q
max
:
kpulse ¼ΔQ
Qmax
ð1Þ
Steadiness factor k
st
, the ratio that characterizes min fluid
feed rate Q
min
to max flow rate:
kst ¼Qmin
Qmax
:ð2Þ
Pulse and steadiness factors are mutually-dependent, be-
cause
kpulse ¼ΔQ
Qmax
¼Qmax−Qmin
Qmax
¼1−Qmin
Qmax
¼1−kst:ð3Þ
Hence,
kpulse þkst ¼1:
Table 1 Classification of pulsed drilling technologies
Qflushing liquid flow rate, nrotational speed, Faxial load
137 Page 2 of 7 Arab J Geosci (2019) 12:137
Steadiness factor is also functionally constrained with fluid
flow rate, because
kst ¼Qmin
Qmax
¼Qmax−ΔQ
Qmax
¼1−ΔQ
Qmax
¼1−kpulse:ð4Þ
Intermittency factor k
int
shows ratio of fluid feed pause
duration t
pause
to fluid feed duration t
flow
kint ¼tpause
tflow
ð5Þ
Reversibility time factor k
t
rev
shows ratio of times of fluid
direct t
dir
and inverse feed t
inv
kt
rev ¼tdir
tinv
ð6Þ
Reversibility flow factor k
Q
rev
shows ratio of fluid direct
(t
dir
) and indirect feed flow values (t
inv
).
kQ
rev ¼Qdir
Qinv
ð7Þ
Bench testing of diamond core drilling
with pulse flushing
One of pulsed well flushing methods, namely, intermittent
flushing, has been held in bench-scale conditions in Drilling
laboratory at Department of Technic Prospecting Of Deposits
in National Mining University (Dnipro, Ukraine)
(Kozhevnykov et al. 1990).
Fig. 1 Pulsed flushing methods:
with variable fluid flow (а); with
pulsed fluid flow (b); with
intermittent fluid flow (c); with
revertive fluid flow (d)
Arab J Geosci (2019) 12:137 Page 3 of 7 137
Drilling has been performed with a single-layer diamond
core type 01А3, 59 mm dia, shown in Fig. 2, with four flush-
ing channels.
Drilling was performed on a granite block with IX drillabil-
ity category (Fig. 3). Water was used as drilling fluid.
Rig type ЗИФ-300 (ZIF-300) equipped with auxiliary gear
box together with drilling pump type НБ-3 (NB-3) are the test
bench main components. ЭМР-2 (EMR-2) flowmeter was
used additionally for recording and control of drilling condi-
tions (Fig. 4).
Test results of diamond drilling using
intermittent flushing mode
Flushing mode was being changed during drilling with 01A3
core bit. Drilling was held using continuous flushing, respec-
tive intermittency factor k
int
=0,aswellasintermittentflush-
ing with intermittency factor values of k
int
= 0.2 and k
int
=1.
Drilling was held with different rotation speed and axial load
values. Results of experimental investigation of intermittent
flushing impact on mechanical penetration speed are shown in
Tab le 2.
As it can be seen from Table 1, all examined intermittently
flushed drilling modes provide penetration speed increase as
compared to continuous flushing mode. Drilling efficiency is
affected not only by flushing mode features, but also by nu-
meric values of drilling parameters that provide resultant pow-
er on bottom-hole (Karakus and Perez 2014). There was no
significant wear on the drill bit due to the relatively shorter
drilling depth and the high performance of natural diamond in
the bit.
Table 3shows power values on bottom-hole that corre-
spond to numeric values of rotational speed and axial load in
this investigation.
Efficiency of drilling using intermittent flushing as com-
pared to continuously flushed drilling can be evaluated with
an efficiency criterion K
eff
that presents a ratio of penetration
rate using intermittent flushing V
int
to penetration speed using
continuous flushing V
const
.
Keff ¼Vint
Vconst
ð8Þ
Penetration speed is connected with power on bottom-hole
P by the relation.
V¼P
A⋅S:ð9Þ
where Ais specific energy consumption on rocks destruction
process, Sarea of working face of borehole.
Let us write (1) by taking in account (2), in the form of
Keff ¼Aconst
Aint
Pint
Pconst
ð10Þ
where subscript index Bint^means the parameters taken at
intermittent flushing mode, and index Bconst^means the pa-
rameters taken at constantly flushing mode. Let us introduce
the coefficients which show ratio of downhole power and
energy consumption by using intermittent and constant flush-
ing mode
kP¼P
Pconst
ð11Þ
kA¼Aint
Aconst
ð12Þ
Fig. 2 Diamond drilling bit type 01А3; аgeneral view; btop view; cside view
Fig. 3 Granite block used in a bench test drilling
137 Page 4 of 7 Arab J Geosci (2019) 12:137
Then the criterion of drilling efficiency with intermittent
flushing depends on the ratio of these factors
Keff ¼kN
kA
:ð13Þ
According to data provided in Table 2, efficiency factor
varies from 1.18 to 2.2. Intermittent flushing with intermitten-
cy factor k
int
= 1 affects drilling more than with intermittency
factor k
int
= 0.2. At the same time, power on bottom-hole val-
ue affects penetration speed increase. Efficiency factor in-
crease is shown as a function of power on bottom-hole for
different intermittency factor values is shown in Fig. 5.
As it can be seen from the data shown in Fig. 5,greater
relative increase of penetration speed is achieved with lower
power on bottom-hole values. At the same time, as it can be
seen from Fig. 6, greater increase of absolute penetration
speed corresponds to greater power on bottom-hole values.
It has been shown by Dreus et al. (Dreus et al.
2016a; Dreus et al. 2016b) that intermittent flushing
provides bottom-hole surface temperature change during
diamond core drilling. Therefore, as it has been shown
in investigations ((Vettegrena et al. 2013)), conditions
for intensified rock disintegration can be provided due
to thermal weakening by intermittent impact of high and
low temperatures.
Intermittency factor impact on efficiency criterion is pre-
sented in Fig. 7.
The results shown in Fig. 7confirm that frictional thermal
power performs more efficiently at operating conditions
assumed.
Some more advantages of transition to intermittent dia-
mond drilling mode need to be mentioned. Average liquid
flow under intermittent flushing is defined by expression
Qav ¼
∫
0
T
QtðÞdt
Tð14Þ
where Q(t) is a function of fluid flow variation under constant
feed rate, ttime, and Tperiod (see Fig. 1). Therefore, transition
to intermittent mode allows reducing of flushing liquid, and
consequently, saving drilling mud. Furthermore, the pump
pressure and the power to drive the pump reduces allows to
save power.
Table 2 Results of test banch diamond drilling using core type 01A3
with intermittent flushing
Rotational
speed (min
−1
)
Axial
load
(kN)
Flushing
mode
Intermittency
factor
Penetration
speed (cm/min)
239 7 Intermittent 1 1.23
Intermittent 0.2 1.15
Stationary 0 0.58
239 7 Intermittent 1 1.07
Intermittent 0.2 0.99
Stationary 0 0.48
377 9 Intermittent 1 4.47
Intermittent 0.2 3.64
Stationary 0 3.06
Fig. 4 Test bench general view. 1, rock drilling machine type ЗИФ-300
(ZIF-300); 2, kelly stem; 3, drilling tool; 4, computer; 5, power supply
unit; 6, electronic interface; 7, granite block
Table 3 Test bench values of power on bottom-hole
Rotational speed (min
−1
) Alial load (kN) Power on bottom-hole (kW)
239 7 1.7
377 9 3.4
1.7 kW 3.4 kW
0
50
100
150
200
K
eff
*100%
P
const
k
int
=0.2
k
int
=1
Fig. 5 Efficiency factor increased as a function of intermittency factor
and power on bottom-hole
Arab J Geosci (2019) 12:137 Page 5 of 7 137
Conclusions
The results of performed research show that diamond drilling
using intermittent flushing proves to be an efficient method of
penetration speed improvement.
The research showed that the penetration speed increased
with the consideration of varying operating conditions.
Penetration speed increase constituted 1.18 to 2.2 times, de-
pending on intermittency factor value. Increase in intermitten-
cy factor provides increase in penetration speed.
It has been shown that improvement in rock destruction
efficiency during diamond drilling using intermittent flushing
has been higher in relative values at a lower power on bottom-
hole values. In absolute values, penetration speed increase
after transition to intermittent flushing mode is directly pro-
portional to the power on bottom-hole level.
Utilization of intermittent flushing allows not only to in-
crease penetration speed, but to improve other performance
indicators, such as reduction of flow rate of flushing liquid at
absorption and save power.
Funding information This work was supported by Research Foundation
of Key Laboratory of Deep Geodrilling Technology, Ministry of Land
and Resources, China (No.KF201808).
References
Dreus AYu, Sudakov AK, Kozhevnikov AA, and Vakhalin YN
(2016a) Study of thermal strength reduction of rock formation
in the diamond core drilling process using pulse flushing mode.
Natsional'nyi Hirnychyi Universytet. Naukovyi Visnyk.(3),5–10
Dreus A, Kozhevnikov A, Lysenko K, Sudakov A (2016b) Investigation
of heating of the drilling bits and definition of the energy efficient
drilling modes. Eastern-European Journal of Enterprise
Technologies (7):3, б41–б46. https://doi.org/10.15587/1729-
4061.2016.71995
Fassahov RH, Faizulin IK, Sahapov YaМ, Badretdinov AM,
Yeld ash e v DА, Prokoshelnikov DV, Gurianov AI (2005)
Energy efficiency in hydro-pulse impact on the bottomhole
formation zone Izvestiya vuzov «Problemyi energetiki». №9–
11. 56–60. (in Russian)
Filimonenko NT (2007) The movement of the cut debris in a pulsing
flow, which circulating in the bottom-hole of the well. Naukovi
pratsi Donetskogo derzhavnogo tehnichnogo universitetu.Seriya:
girnicho-geologichnayu 6(125):125–130 (in Russian)
Gorshkov LK, Gorelikov VG (1992) Temperature regimes of diamod
drilling. Nedra, Moscow (in Russia)
Karakus M, Perez S (2014) Acoustic emission analysis for rock-bit inter-
actions in impregnated diamond core drilling. Int J Rock Mech Min
Sci 68:36–43
Kollé J, Marvin M (1999) Hydropulses increase drilling penetration rates.
Oil Gas J 97(Issue 13):33–37
Kozhevnykov АА (1992) Pulse technology of drilling wells. Proceedings
International Conference "Rocks mechanics at drilling"–Groznyi.
43 –44. (in Russian)
Kozhevnykov AA, Filimonenko NV (2010) Ways of impulse washing of
wells Natsional'nyi Hirnychyi Universytet.Naukovyi Visnyk 6:28–
32 (in Russian)
Kozhevnykov, A.A., Vyrvinsky, P.P., Dyachenko, Yu.G., Yacenko N.D.
(1990) Bench drilling research with impulse flushing // Proceedings
V Vsesouznoi Conference « Destruction of rocks at wells drilling».–
Ufa –С.43–44. (in Russian)
Liu Y, Wei J, Ren T, Zhaohui L (2015) Experimental study of flow field
structure of interrupted pulsed water jet and breakage of hard rock.
Int J Rock Mech Min Sci 78:253–261. https://doi.org/10.1016/j.
ijrmms.2015.06.005
Perez S, Karakus M, Pellet F (2017) Development of a tool condition
monitoring system for impregnated diamond bits in rock drilling
applications. Rock Mech Rock Eng 50(5):1289–1301
Qu H, Li G, Jiang D (2016) Mechanisms and application for hydraulic
pulsed cavitating jet generator. Advances in Petroleum Exploration
and Development 12(2):1–12. https://doi.org/10.3968/pdf
Shi H, Li G, Guo B, He Z (2015) Hydraulic pulse jet: test of characteris-
tics and field applications in ultra-deep wells. J Nat Gas Sci Eng 27:
200–206. https://doi.org/10.1016/j.jngse.2015.08.053
Tungusov SA (2009) Improving the efficiency of drilling wells by pulsed
flushing. Razvedka I ohrana nedr 8:42–47 (in Russian)
Vettegrena VI, Mamalimova RI, Sobolevb GA, Kireenkovab SM,
Morozovb YA, Smul’skaya AI (2013) Temperature-induced phase
transition in quartz nanocrystals dispersed in pseudotachylite. Phys
0,0 0,2 0,4 0,6 0,8 1,0
100
125
150
175
200
225
250
K
eff*100%
k
int
1- P=1.7 kW
2- P=3.4 kW
2
1
Fig. 7 Intermittency factor k
int
impact on efficiency criterion on
intermittent flushing for different power values
1,0 1,5 2,0 2,5 3,0 3,5
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
1 -
const
2 - intermitten
t
V, cm/min
P, kW
2
1
Fig. 6 Dependence of penetration speed on power on bottom-hole for
different flushing modes
137 Page 6 of 7 Arab J Geosci (2019) 12:137
Solid State 55(5):1063–1069. https://doi.org/10.1134/
S1063783413050338
Wang Z (2005) Discussion on theory and methodology of suction-pulse
drilling technique. Oil Drill Prod Technol 27(6):13–15
Wang D, Zhang W, Zhang X, Zhao G, Zuo R, Ni J et al (2015) The China
continental scientific drilling project: CCSD-1 well drilling engi-
neering and construction. Springer, Berlin
Arab J Geosci (2019) 12:137 Page 7 of 7 137
