2015 HERIOT-WATT UNIVERSITY INSTITUTE OF PETROLEUM ENGINEERING ECLIPSE TUTORIAL 1 (3D 2-Phase) A
Prepare an input data file for simulating the performance of a two-phase (water/oil) reservoir. The model model will will have have a regula regularr shape, shape, with two wells wells at opposi opposite te corne corners rs to simula simulate te production in a quarter five-spot pattern.
GRIDDING AND ROCK DATA (GRID)
The 3D section of reservoir being modelled has dimensions 2500' x 2500' x 150', and it is divided into three layers layers of equal thickness. The number of cells cells in the x and y directions are are 5 and 5 respectively. Other relevant data are given below, below, using field units throughout: Depth of reservoir top: Porosity:
8000 ft 0.20
Permeability in x direction: Permeability in y direction: Permeability in z direction:
Layer 1 200 mD 150 mD 20 mD
Layer 2 1000 mD 800 mD 100 mD
1
2
Layer 3 200 mD 150 mD 20 mD
3
4
5
50 0
50
50 0
50
50 0
50
50 0 1
50 0 2 1 3 2 4 3 5 50 0
50 0
50 0
50 0
50 0
Figure 1: Schematic of model.
1
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FLUID PVT AND FLUID-ROCK INTERACTION PROPERTIES (PROPS)
Water and Oil Relative Permeability and Capillary Pressure Functions k rw
k ro
Pcow (psi)
-- table 1 for 1000mD 0.15* 0.45 0.68 0.8
0.0 0.2 0.4 0.55
0.9 0.3 0.1 0.0
4.0 0.8 0.2 0.1
-- table 2 for 200mD 0. 0.25* 0. 0.5 0. 0.7 0.8
0.0 0.2 0.4 0.55
0.9 9.0 0.3 1.8 0.1 0.45 0.0 0.22 * Initial saturation throughout layer.
Water Saturation
Water PVT Data at Reservoir Pressure and Temperature Pressure (psia) 4500
Bw (rb/stb) 1.02
cw
µw
(psi-1) 3.0E-06
(cp) 0.8
Oil PVT Data, Bubble Point Pressure (Pb) = 300 psia
Pressure
Bo
Viscosity
(p (psia) 300 80 800 6000
(rb/stb) 1.25 1.20 1.15
(cp) 1.0 1.1 2.0
Rock Rock comp compre ress ssib ibili ility ty at 4500 4500 psia psia:: 4E-06 4E-06 psi psi-1 Oil Oil de density sity at su surfa rface condit nditio ion ns: 49 lbs lbs/c /cf f Water Water dens density ity at at surfa surface ce cond conditio itions: ns: 63 lbs/ lbs/cf cf
INITIAL CONDITIONS (SOLUTION)
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The oil-water contact is below the reservoir (8,500 ft), with zero capillary pressure at the contact.
WELLS AND PRODUCTION SCHEDULE (SCHEDULE)
Drill two wells: producer PROD, belonging to group G1, in Block No. (1, 1) injector INJ, belonging to group G2, in Block No. (5, 5) The inside diameter of the wells is 8". Perforate both the producer and the injector in all three layers. The datum depth for pressure measurements during production is 8,000 ft – i.e. the pressure gauge is located just above the top of the completion. Produce at the gross rate of 10,000 stb liquid/day with a minimum bottom hole pressure limit of 2,000 psia Inject 11,000 stb water/day with a maximum bottom hole pressure limit of 6,000 psia. Start the simulation on 1st January 2009, and use 10 time steps of 200 days each.
OUTPUT (SUMMARY, GRID & SCHEDULE)
Ask the program to output the following data: · Initial permeability, porosity and depth data (keyword (keyword INIT in GRID section) · Initial grid block pressures and water saturations into a RESTART file (keyword RPTRST RPTRST in SOLUTION section – set ‘BASIC=2’ to give basic dynamic output at t = 0) · Fi Field Average Pressure (FPR) Bottom Hole Pressure for both wells (WBHP) Field Oil Production Rate (FOPR) Field Water Production Rate (FWPR) Total Field Oil Pr Production (FOPT) Total Field Water Production (FWPT) Well Water Cut for PROD (WWCT) CPU usage (TCPU) to a separate Excel readable file fi le (using keyword EXCEL) in the SUMMARY section. · Grid block pressures pressures and water saturatio saturations ns into RESTART RESTART files at each each report report step of the simulation (keyword RPTRST in SCHEDULE section – again set ‘BASIC=2’ to give basic
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PROCEDURE
1 Edit file TUT1A.DATA in fol fold der \eclipse\tut1 by openin opening g it in Notepa Notepad, d, fill in the the necessary data, and save the file. (Make sure the file ending is .DAT .DATA and not .tt! 2
Activa Activate te the the ECLIP ECLIPSE SE Laun Launche cherr from from the the Deskt Desktop op or or the Start Start menu. menu.
3
Run Run ECL ECLIP IPSE SE and and use use the the TUT TUT1A 1A data datase set. t. 4 When the simulation has finished, finished, use ECLIPSE Office -> Results and menu menu File -> Open -> SUMMARY -> All Vectors, or use MS Excel to open the output file TUT1A.RSM , which will be in the \eclipse\tut1 folder. 5 Plot the BHP of both wells (WBHP) vs. time and the field average average pressure pressure (FPR) (FPR) vs. time on Figure 1. 6 Plot the water cut (WWCT) (WWCT) of the well PROD and the field field oil production production rate (FOPR) vs. time on Figure 2. 7 Plot on Figure 3 the BHP values for the first 10 days in the range 3,500 3,500 psia to 5,500 psia. Explain the initial short-term rise in BHP in the injection well and drop in BHP in the production production well. well. Account Account for the subsequent subsequent trends trends of these two pressures pressures and of the field average pressure, relating these to the reservoir production and injection rates, water cut and the PVT data of the reservoir r eservoir fluids.
B
Make a copy of the file TUT1A.DATA called TUT1B.DATA in the same folder tut1. By modifying the keyword TSTEP change the time steps to the following: 15*200 Modify the WCONINJ keyword to operate the injection well at a constant flowing bottom hole pressure (BHP) of 5000 psia, instead of injecting at a constant 11,000 stb water/day (RATE) – i.e. delete reference to 11000 and replace with 1*. Add field volume production rate (FVPR) to the items already listed in the SUMMARY section. Run Eclipse using the TUT1B.DATA file, and then plot the two following pictures: Figure Figure 4: 4: both well bottom hole pressure pressuress and field average average pressure pressure vs. time, showing showing pressures in the range 3,700 psia to 5,100 psia Figure Figure 5: field water water cut and field field volume volume production production rate rate vs. time
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Account for the differences between the pressure profiles in this problem and Tutorial 1A. To assist with the interpretation, calculate total mobility as a function of water saturation for the 4 saturation points given, using: MTOT(Sw) = + and show how this would change change the differential differential pressure across across the reservoir reservoir as the water saturation saturation througho throughout ut the reservoir reservoir increases. increases. From Figure Figure 5, explain the impact impact of the WWCT profile (fraction) on the FVPR (rb/day).
C
Copy file TUT1B.DATA to TUT1C.DATA in the same folder.
This time, instead of injecting at a constant flowing bottom hole pressure of 5000 psi, let the simulator calculate the injection rate such that the reservoir voidage created by oil and water produc production tion is replaced replaced by injected injected water. water. To do this, this, modify modify the contro controll mode mode for the injection well (keyword WCONINJ) from BHP to reservoir rate (RESV), and use the voidage replacement flag (FVDG) in item 8. Set the upper limit on the bottom hole hole pressure for the injection well to 8,000 psia again. Note the definitions given given in the manual for item 8 of the WCONINJ WCONINJ keyword. Based on the definition for voidage replacement, reservoir volume injection rate = item 6 + (item 7 * field voidage voidage rate) Therefore, to inject the same volume of liquid as has been produced, set item 6 to 0, and item 7 to 1. Run Eclipse using the TUT1C.DATA file, and then run Floviz or Petrel, to display the grid cell oil saturations (these displays need NOT be printed). Discuss the profile of the saturation front in each layer, and explain how it is affected by gravity and the distribution of flow speeds between the wells.
SENSITIVITIES For the sensitivity calculations try variations of +/- 10% from the base case (TUT1A), and use a spider diagram to plot the results. (i) (i)
Long Long-t -ter erm m beha behavi viou ourr (0-2 (0-200 000 0 days days): ): Assess impact of varying oil formation volume
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Short-term behaviour (0-10 days): Assess impact of varying absolute permeability and separately the porosity on bottom hole pressure response (WBHP) in either of the wells. (ii) (ii)
Mobil obilit ity y effe effect cts: s: What happens happens to the pressure pressure differential differential between between the wells when when you use straig straight ht line line rel perms perms (by deleti deleting ng rows rows in SWOF SWOF keywor keyword d contai containin ning g satur saturati ation on points points 0.5 and 0.7? 0.7? What What if you then then change change the values values of the relative relative permeability endpoints (initially Krw = 0.55 and Kro=0.9)?
(iii) Study impact of oil density and total flow rate r ate across field on flow distribution in field.
D
Copy file TUT1A.DATA to TUT1D.DATA in the same folder.
The data file should be adapted to include the following features: • Porosities varying according to layer (PORO in the GRID section) • NTG varying according to layer (NTG in the GRID section) • Water saturations that can go up to Sw=1 should there be an oil-water contact introduced into the model To implement these, replace the entire GRID section with the following: --================================================================ GRID EQUALS -- Keyword DX DY DZ &'(S
!
value 500 500 50 )000
X1 X2 1 5
Y1 Y2 1 5
Z1 Z2 1
! ! !
w"ole #odel $a#e a$ a%ove $a#e a$ a%ove
1
5
1
5
1
1
!
*r+d layer 1
(ER,X (ER,Y (ER,Z ('R' &G
200 150 20 0.1/ 0./5
1
5
1
5
1
1
! ! ! ! !
*eolo*+al layer 1
(ER,X (ER,Y (ER,Z ('R' &G
1000 )00 100 0.20 0.//
1
5
1
5
2
2
! ! ! ! !
*eolo*+al 2
(ER,X (ER,Y (ER,Z ('R' &G
200 150 20 0.1/ 0./5
1
5
1
5
! ! ! ! !
*eolo*+al
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-- 8aer a4d o+l rel er#$ 9 a+llary re$$ure$ -Sw Krw Kro ( --------------S8': -- a%le 1 3or 1000#D 0.15 0.0 0./ ;.0 0.;5 0.2 0. 0.) 0.<) 0.; 0.1 0.2 0.) 0.55 0.0 0.1 1.0 1.0 0.0 0.0 ! -- a%le 2 3or 200#D 0.25 0.0 0./ /.0 0.5 0.2 0. 1.) 0. 0.; 0.1 0.;5 0.) 0.55 0.0 0.22 1.0 1.0 0.0 0.0 !
Run Run the the mode modell in ECLI ECLIPS PSE, E, visu visual alis isee the the grid grid in Flov Floviz iz or Petr Petrel el,, and and plot plot the the same same properties properties as in TUT1A. TUT1A. The purpose purpose of this part of the exercise exercise is to familiaris familiarisee you with some features of ECLIPSE that you will find useful later. No in depth analysis of of results is required for part D, but it will be used as a starting point for Tutorial 2.
Eric Mackay
19th January 2015