lt30019tyofWtrolNm Engktem I
Interactive Reservoir Simulation
J.M.M. Regtien ***, G.J.A, Por *, M.T. van Stiphout and F.F. van der Vlugt
Shell Research Rijswijk
This paper W= prepared wpmsentatbn at the Isth SPE Sympo8ium cmReamoir Simulation held in San Antcmim~i U.S.A., 12-15 Febr_ 1ss5.
This paper was adectsd for presentation by an SPE Program C0mmittc8 fdlowlng review of Information contaitmd in an 8b8tmcf submitted by the aufhor(a). C0nt0nf8 of the paper,
MPMWntOd, haw not been mdevmd by the Sodafy of Petrofeum Ewirwm and we subject to correction by the author(a). Tim material, as presented, &ma not neceaawify reflect
MY_ ~t~ *~fy ~p~~um Emi~m. ~off~m, of ~m~. pp -m ~SpE *W We Wb@f to Publi@tbn r- by Edhmial ~mm~ of t~ *kW
of Petroleum Er#irmom. Pennklontocopy ismabbbd @an~dtimtb ~*.lll@@tis m9tib~. ~=**M_nm*ws~@
of whue and by whom the -r is Pm8snted. Write Libmfbn, SPE, P.O. Box SSSSSS,Rbh~dfm ~7~1 U.S.A. TOkX,1SS245 SPEUT.
Shell’s new Modular Reservoir Simulator (MoReS) has keen
equipped with acomprehensive and versatile user interface called
FrontEnd. Apart from providing auser-friendly environment for
interactive reservoir simulation, FrontEnd serves as asoftware
platform for other dynamic simulation and reservoir-engineering
applications. It offers to all supported applications acommon user
interface, enables the re-use of code and reduces overall maintenance
and support costs associated with the embedded applications.
Because of its features, FrontEnd facilitates the transfer of research
results in the form of operational software to end users.
When coupled with MoReS, FrontEnd can be used for pre- and post-
processing and interactive simulation. The pre-pmcessing options
allow data to be inputted by means of various 0SFM40tif widgets
containing aspreadsheet, text editors, dialogues and graphical input.
The display of the input data as well as the post-processing of all
simulation results is made possible by avariety of user-defined plots
of tabular (e.g. timestep sumtmwy) and array (simulation grid) data.
During asimulation user-defined plots can be displayed and edited,
allowing aclose inspection of the results as they are being calculated.
FrontEnd has been equipped with apowerfui input command
language, which gives the batch user as much flexibility and control
over the input as the interactive user.
Theintroduction of powerthl workstations offers opportunities to
change the way reservoir simulations are carried out. Most current
reservoir-simulation software require the engineer to assemble adata
deck with atext edhr or dedkated pmprncessors, submit the run in
batch mode, wait for its execution and then investigate the results
using post-processing software . Yet current hardware is powerful
enough to run interactive simulations whose results can be monitored
as they are being calculated. Such interactive simulation can increase
the efficiency of the engineer significantly. Since the data can be
immediately displayed and validated, obvious errors can be detected
early and alternative scenarios can be quickly evaluated.
To make Shell’s new Modular Reservoir Simulation package MoReS
 fully interactive, it has been equipped with aversatile and
powerful user interface called FrontEnd.
BRIEF DESCRIPTION OF MQBES
reservoir simulator offers alarge choice of fluid
&scriptions, ranging from standard black or volatile oil to user-
specified multicomponent mixtures. In addition, tracers, pcdymers
and chemical reactions are handled for various specialist applications
(e.g. reservoir souring, environmental applications etc.). The
simulator can be operated in either anon-fractured or fractured mode
[2, 5, 6]. In the latter case dual porosity, dual permeability and block-
to-block flow (oil re-infiltration) can be taken into account. The
program has also been equipped with various options to effectively
** Cumntiy with Brunei Shell Petroleum 545
2Interactive Reservoir Simulation SPE 29146
handle detailed and realistic three-dimensional (statistically derived)
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pressure models is availabl% aspecial module then generates either
static or dynamic pseudo-curves for use on acoarse grid.
The program’s well model accurately simulates vertical, deviated and
horizontal wells, including crossflow. The well-management package
is, by default, coupled to the wells of the subsurface simulation
model, but it can also be used in astand-alone fashion with user-
supplied well potentials. This feature means that acomplicated
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CRIPTION OF FRONT~
FrontEnd is best described as asoftware platform for dynamic
modelling applications. So far, it has mostly been used for the pre-
and post-processing of both reservoir-simulation input data and
results and the run-time control of (interactive) applications.
FrontEnd offers to all applications it supporkY
●acommon graphic user interface for data input and display
●access to internal application data via adata dictionary;
●apowerful input command language for batch input as well
as for arithmetic manipulation and display of all available
application data (variables, tables, array data);
●real-time simulation and animation;
●tisll restart captillities;
●an on-line documentation system, and
●an interface to spreadsheets and third-party 3D
vistralisation programs .
The graphic user interface consists of amenu bar and two main
windows. The first window contains the “’Dictionary”(Figure 1),
which manages data transmission to and from the user. The second
window is the “Panorama” window (Figure 2); through it, the user
can SIXthe data displayed. Depending on the user settings, various
methnds to edit or browse through the data are available.
All relevant application data in FrontEnd can be visualized in the
form of icons grouped in ahierarchical structure, like that used in the
well-known Macintosh or Windows desktops. Each data type has its
own unique icon. Aselection of the supported data types is visible in
Each of the icons allows access to the data in one of several
supported representations in the Panorama window. The number of
representations depends on the object type:
●XY cross plot (for tables);
●SprUdSk?t (for =JW and tables);
●editable dialog with widgeta (all~
●colour-fill plots (for arrays);
●editable text (all).
Representations combining data from different applications can also
The user can add plot representations that will be stored with the data
for later use. The plot components (axes, legenda, colours, titles, data
points) are filly editable.
The advantages of such an icon-based data dictionary are obvious:
●The user always has access to all relevant application data,
which are organised in aclear way.
●‘he data can be checked, visualized and edted at any time.
●No prior choice of ouQut type is rquired.
Access to the data via “tiedictionary is possible not only by way of
interactive methods but also through the text input (e.g. for batch
running); for the latter the FrontEnd input command language is
Interactive simulation allows the engineer to visualise any of the
results while the simulator is time-stepping. At any moment,
however, he or she can interrupt the simulation, change the input
(e.g. well controls) and then continue. Except for the grid dimensions
and the maximum number of phases and components, any data can
be changed before or even after reservoir initialisation.
Such interactive simulation increases the efficiency of the engineer
●results are available immediately;
●incorrect results can be detected on the spot, allowing the
user to abort the rms and thereby spare computer resources;
●“what if’ scenarios can otlen be executed much more
r-s,=t.~~for ins~.~, the cause of convergence problems (e.g., an
erroneous transmissibility or very small pm volume in alarge or
complex simulation) can be quickly spotted and corrected.
Weff planning is made easier with FrontEnd, since it enables the
user to define awell’s trajectory and its perforations. The
simulator can then be requested to calculate the position and
properties of perforations and to determine the well’s potential.
By varying the trajectory, one can determine an optimum
location for the well.
Alarge simulation model can be run on ahigh-end workstation,
whilst the FrontEnd windows are visible on aPC using X-
windows and TCP/IP network software. Windows to other PC-
baaed computer applications, such as word-processing and
spreadsheet pmgrasrss,can be placed next to the FrontEnd
windows. The progress of the simulation can be monitored by
activating any of the default or user-defined output and plot
options. The table or array plots will then be updated at every
Wells that are shut-in smexpectdy ‘becauseof iifi die-out can
be examined in detail by setting up plots of the intake pressure
curves and the inflow performance of the well. The parameters
necessary to interpolate between the data in the multi-
dimensional vertical-flow or lift tables are taken fmm the well,
and the well inflow performance curve reflects the actual
Aseparate well-potential cdxdation dialog has been added that
can be used at any time to study the effects of various
SPE 29146 J.M.M. Regtien, G.J.A. Per, M.T. van Stiphout and F.F. van der Vlugt 3
constraints imposed on awell. The resulting (potential) flows
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displayed on the computer screen or printed.
The FrontEnd input command language first of all provides keyword
input for the applications to be run in batch mode. For production
runs this mode of operation is often preferred, since it avoids
repeating the same sequence of interactive actions. Secondly, it
enables the user to customise FrontEnds firnctionahty. TM essential
feature is best illustrated by example.
The implementation of well management in areservoir simulator is
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tend to be field-specific. Hard coding these in the simulator itself
would result in amassive and costly programming effort. With
FrontEnd, however, several optional programming constmcts can he
called upon to modify or extend the simulator’s functionality:
●access to all relevant data via the dictionary;
●creation of user-defined data objects;
●“if” statements and” while” loops;
●apre-defined function library;
●flexible unit conversions;
●user-defined file I/O;
ethe C:eatiml &id dkirlg c! p!ots;
●access to the operating system.
The input command language also allows the specification of what
are called monitors: functions that are evaluated by the application
whenever aset of user-defined conditions are met. The first one and
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command language enhances the applications it supports.
Screening economics-present vrdue, cash flow, net revenue
and cumulative cash flow-can be automatically calculated
from the output of asimulation mn on the basis of user-defined
discount factors, oil prices, and capital and operating expense
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can all be included in the user’s input data.
Correlations often describe PVT and saturation data or porosity-
permeability relationships. Such correlations can now be coded
and customised by the user. Although alibrary of various
indu$m t.~rrt=l~t;nmiQ nmvidd the IIcer can m-mvand modify
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them to suit local conditions.
Well-management policies can be implemented by comparing
well production data with targets. Wells and intervals can be
shut-in or opened up on any of the user-defined criteria. Water
breakthrough in one well may thus automatically result in
certain actions at other wells.
Alarge simulation model in history-match mode can be made to
stop by itself when the computed results deviate too much from
the historically observed data. This option saves troth the
computer’s and the engineer’s time.
5. The simulator can he used to study the feasibility of atime-lapse
seismic survey, by calculating relevant seismic parameters from
the simulated reservoir properties. The property data are
gathered automatically during the simulation and, directly after
its completion, the changes in seismic parameters showing the
movement of fluid contacts are made available.
The most important function of FrontEnd as apre-processor is to
check data. All basic data types, such as variables, tables and arrays,
~h~r. ~Svstem of ch~ks on rnInjrnUrn md maximum allowed values.
Tables contain checks on the required monotonicity of the data in the
columns. The built-in capabilities for the handling of dimensional
units automatically ensure that two numbers of different quantities
(e.g. pressure and mass) are not equated, added, subtracted or used in
an assignment. Adefault unit system can be selected, or alocal set of
units can be defined as the default. In addition, data can be entered in
terms of any unit merely by adding the unit expression after the data
All tabular input (PVT, relative permeabilities, capillary pressures,
vertical flow, historical production data) can be plotted and
inspected. Tables can be re-interpolated or filled using user-defined
correlations. When two two-phase relative permeability tables are
used in combination with athree-phase model, the resulting three-
nhace relative nermeahi Iities can be @oti in aternary dl~=~.
r---- ------ .- ~- . ...-_-. ..._-_ _
Most of the well data are generally stored in corporate databases;
they commonly need reformatting before they can be used as
simulator input. FrontEnd has therefore been equipped with an
interface to aproject database that automatically converts well
tldinitinn (tmicctnrv and completions) and performance &tS
---------- .--J -- - ,-
(historical rates and pressures) directly into FrontEnd objects that the
simulator can use.
An extensive on-line help system with search and browse facilities is
coupled to the FrontEnds data dictionary. All icons contain heip
information, and the collected information pertaining to all
application objects forms areference manual that can be printed as a
PostScript file. The user can use the same functionality to document
P-t pr=w@MMms .
The reservoir simulator MoReS as well as other FrontEnd-supported
applications can create and fill tables and arrays that can later be used
by FrontEnd. For example, the simulator generates, for all wells and
surface network nodes, default tables of presaums, rates, ratios
(GOR, BSW, etc.), cumulative volumes of fluids producedinjected.
These tables can be plotted and compared with observed data. In
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one plot. Similarly, the properties of the subsurface grid can be
displayed in the colour-fill plots. Any of the existing array data can
be used to calculate new parameters. For example, awater%od-
movable oil array can be calculated from auser-defined algorithm
incorporating existing data.
4Interactive Reservoir Simulation SPE 29146
Plots can be combined in multiple views (Figure 3). Any number of
these views can be defined for interactive or batch plotting. Plots of
@e surface network, for instance, can easily be generated (Figure 4).
All flow rates and active well-management policies cart be accessed
by selecting the various objects in the network plot.
Three-dimensional visuaiisation has riot beetr iinpielmfiritedkr
FrontEnd, given the 3D reservoir-simulation visualization software
available in the OFI market . Instead, interfarm have been written
so that simulation results and gridded data can be visualized with two
leading commercial packages.
Quality assurance of the simulation rnr@ by peer m+GIVia.i
.- .- —-.,:.-.
review is made quite easy. The reviewer merely opens arestart file
and systematictdly checks the basic input and the resultw there is no
need to do additional simulations.
Tables and arrays can be written in afile format for expott to
spreadsheet programs or in any user-defined file format. Plot files
c~~ ~. gen~m~ in postscript fofmat for printing on their own or for
inclusion in other documents and presentation material.
Both MoRes and FrontEnd have been developed using the latest
industry standards and technology. The implementation languages
.-. e%. *h. M., ;.email@example.comP mm-lFn~-77 for&e CidCUkltiOn core Of
us, b.“. “.” ..s.,. .. . ..-+ -.-. . .
the applications. The design is fully object oriental the Clanguage
has been used to implement aclass structure with standatd software
~=,wnen~, ~i~ Ohierts. that mav ifierit properties ~d data from
., —-, -— —.-,
other objects. OSF/Motif and Xl 1are the packages used to
implement the graphic user interface and the screen graphics. The
POSC user-interface guidelines  have been followed as much as
Possibl% plot file output follows postscript standards. Adherence to
programming standards is strict, resulting in an excellent portability.
There is only one version of the current package, which is
operational on various hardware platforms.
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TiW auaptabk fulkuoll=a~, U. ..V8.U.U A., .. .-
its first major application, the MoReS reservoir simulator, has
prompted Shell software developem to rely on FrontEnd as user
interface for other reservoir-modelling applications. Tbe following
applications are now available in the FrontEnd environment
REDUCE: areservoir simulation pre-pmcessing package that
compresses &tm”led(geostatktical) geological models of multi-
rnillionceh!rinto auser-dejined simulation grid (Figure 5).
The compression includes not only the scaling up of properties like
porosity and permeability but also the calculation of comerpoints
and transmissibilities for the simulator grid blocks. Various
averaging techniques are available to coarsen the geological model
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Wniie PreSWvliig IQ IILUaLu@k UU.. ..V” =.- . .. . .. ... .—
PROJECTDAT~SE: on inte~ace that connects thereservoir
simulator to petroleum-engineering databases and applicatwns,
coqrorate &tabases (historical production&to ~generic well
&to like well tmjectories andptvjoratwns) orpre-processing
applications (grid generation; PVT table;, pseudo relutive
permersbilities and capillary pressures; il@tabks).
PROJBCT DATABASE stores all these data allowing
working on the same project to share them. FrontEnd can be use
to browse through the database (with the aid of the dictionary)
load datq into the reservoir simulator.
FRACNET: awell-test package for horizontal wells in sparsely
FRACNEI’ generates arbitrary fracture geometries and
the response of awell connected to the fmcture network as a
fii=titi, u. UI..W. x.W---- .. . . .
,.s M-. 17m.md k,Id to sp:fy t~e fractuR
and other test parameters as well as to visualise and analyze the
SUBCAL arnodellingpackage that con be used to predict
compaction and swfhce subsidence as aresult of theproduction
AvarietyGfmde:iirig CPU..- -. ..—.— . .. . .. .-...-=.
.&,.... .- mat+ .vailahlp thmll~h
FrontEnd, including an optional link with the reservoir
OtbCrzippiicztimisthat aii bekig rieve!qree wrrtodifk! huse
within the FrontEnd environment are
1. apackage for forecasting acompany’s medium- and long-ter
production on the basis of individual teservoir forecasts
originating from various sources, from decline curves to
field reservoir simulatiotu
2. agas-field planning td  consisting of athird-party
network model, asubsurface simulator (reservoir simulator
and/or material-balance tank models) and adriver that handl
the contracts and steers the subsurface and surface simulator
Auser-friendly pre- and post-processing environment for
reservoir simulation has been developed. It adds anew,
interactive dimension to reservoir .$imuiSdOmi—india”e
to Mrelevant simulation data at any titnq data validation
visualization of results in various forms; and full user control
the course of asimulation as it is being run.
Application of the fully integrated FrontEnd/MoReS
has Ied to pre- and post-processing that are more efficient
higher quality than that done with conventional simulation
sotlware, which consists of asuite of separate pre- and post-
One of the key elements of FrontEnd has been its flexible
mmmand language. The language’s programming features
enable the user to enhance data analysis and customise the
FrontEnd has also been successfully developed into a
for dynamic rwervoir-modelling applications other than
reservoir simulation. It offers the user acommon user
for all embedded applications. The re-use of code and
overall maintenance and suppott coats are additional benefits
Because of itt versatiiiey and s“a!iiitjy, ~i%on’~-dlets new
SPE 29146 J.M.M. Regtien, G.J.A. For, M.T. van Stiphout and F.F. van der Vlugt 5
research developments quickly become operational software.
Rogers, W.L., Ingalls, L.J. and Praa@ S.J.: “Prc- and
Postprocessing for Reservoir Simulation”, SPE 20360.
Per, G.J.A., Boerrigter, P.M., Maas, J.G., and de Vries, A.S.: “A
fractured reservoir simulator capable of modelling block-block
interaction”, SPE 19807.
Wells, M. and Watkins, H.: “3-D visualization of multivariate
reservoir simulation data on complex grids”, presented at the
1992 IBM Europe Institute conference on Computational
Methods and Tools in Reservoir modelting, 17-22 August 1992,
POSC User Interface Style Guide, version 1.0
.,.. n:a...... r=m“..AW.11,.. T.W2_,,”4..-A -“—...:-
val, “,, MI,,,, G.ti. al,” ,, m-, , , . . ,., a&Lul Fa4 ,Cz.w v“,,
simulation and field developmen~ Natih field (Oman)”, SPE
Bccrrigter, P.M., van der Lcemput, L.E.C., Pieters, J., Wit, K.,
and Ypma, J.G.J.: “Fractured Rmervoir Simulation: Case
Histories”, SPE 25615.
Hooi, H.R.., Goobie, L., Cook, R. and Choi, J., The integrated
Team Approach to the Optimization of aMature Gas Field,
paper SPE 26144, presented at the SPE Gas Technology
Symposium, Calgary, 28-30 June 1993 @mceedings pp. 73-80)
The authors wish to thank the management of Shell Research BV and
Shell International Petroleum Maatschappij for permission to
publish this work.
Fig,,1Dictionary dispiay of (soieotsd) reservoir
Fig. 2Panorama dispiay of adata oioject (saturation array).
. . .
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dDr.rto,l13074 552 FIGS. 4,5