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Unconventional reservoirs consist of matrix, micro-fractures, and macro-fractures. There is a significant difference between stress-dependent deformation of matrix rock and the fracture-containing reservoir frame. These differences are great enough to affect the long-term production performance of reservoir. Thus, accurate representation and modeling of such diverse characteristics are needed to predict reservoir performance. Changing reservoir pore pressure during production causes decrease in porosity and permeability and deforms the pore geometry. Thus, in mathematical modeling, reduction in pore volume is a rock deformation issue including the ever-changing pore compressibility. Typically, coupled geomechanics and flow simulation models do not account for such details; however, in this paper, we used in-house multi-phase dual-porosity model to show the effect and significance of compaction drive on production performance of a Bakken reservoir. We have observed that the energy provided by the reservoir compaction increases cumulative fluid production, and numerical models that has constant compressibility values in their transport equations underestimates the cumulative production. Our modeling results indicate that the energy provided by the reservoir compaction increases cumulative fluid production by eleven percent for the Bakken example. Thus, using the results of this paper, we demonstrate the effect of rock elastic properties and stress-dependent porosity and permeability on reservoir long-term performance. |
