Comparison of Solutions to a Three-Dimensional Black-Oil Reservoir Simulation Problem (includes associated paper 9741 )

Abstract

Summary A comparison of solutions to a three-dimensionalblack-oil reservoir simulation problem is presented.The test of the problem and a brief description of theseven simulators used in the study are given. Introduction Seven companies participated in a reservoirsimulation project to compare the results obtained bydifferent black-oil simulators. The companies werechosen to give a good cross section of the solutionmethods used in the industry. The participants wereAmoco Production Co., Computer Modelling Groupof Calgary (CMG), Exxon Production Research Co., Intercomp Resource Development and EngineeringInc., Mobil Research and Development Corp., ShellDevelopment Co., and Scientific Software Corp.(SSC). The paper presents the text of the problem, acomparison of results in graphical form, and a briefdescription of each model. The descriptions weresupplied by the participants. A variety of computers was used. Amoco usedIBM 3033, IBM 370/168, and Amdahl V/6. CMGused Honeywell 6000 DPS, and Exxon used Amdahl470/V5 and IBM 370/168. Intercomp used Cray-1and Harris/7. Mobil and SSC used CDC Cyber 175, and Shell used Univac 1110/2C Level 36. Thenumber of time steps and the central processor timesvaried considerably. Those interested in the actualvalues should contact the individual companies. Except for Shell, all the participants usedsingle-point upstream mobility weighting. Shell used twopoints upstream. Constraints and data are given inthe text. Statement of the Problem Areal and cross-section views of the reservoir aregiven in Figs. 1 and 2. The grid system is given in Fig.1. Stratification and reservoir properties are given inFig. 2. The reservoir is initially undersaturated. A gasinjection well is located at Grid Point (1, 1), and aproducing well is located at Grid Point (10, 10).Pertinent data and constraints are given in Table 1.PVT properties and relative permeabilities are given in Tables 2 and 3. The participants were asked tomake the runs and report the results described below. Runs To Be Made Case 1 Let the bubble-point (saturation) pressure beconstant with a value equal to the original value. Case 2 Let the saturation pressure vary with gassaturation - i.e., this is a variable saturation-pressurecase. The PVT lines at pressures above the calculatedsaturation pressures are parallel to the original line. Results To Be Reported The following results are to be reported.1. Plots of:a. Oil rate vs. time.b. GOR vs. time.2. Report annually and at abandonment:a. The pressures of the cell where the injectorand producer are located.*b. Gas saturation at Grid Points (1, 1, 1), (1, 1,2), (1, 1, 3),(10, 1, 1), (10, 1, 2), (10, 1, 3), (10,10, 1), (10, 10, 2), and (10, 10, 3).3. Report at the end of 8 years:a. Tables of gas saturation.b. Tables of cell pressures. *c. Tables of saturation pressures for the variablesaturations-pressure case. * JPT P. 13^