In general, conventional oil and gas reservoirs are not deformed significantly. However, some unconventional reservoirs including those of methane hydrate and heavy oil/bitumen are soft and deformable. Therefore, it is important to introduce the geomechanical effects such as the changes in porosity/permeability associated with the deformation of a reservoir for accurately predicting production performances for these unconventional reservoirs.
Recently, the reservoir fluid flow behavior has been simulated in conjunction with geomechanics simulation, using various coupling methods such as fully implicit method, explicit method, iterative method, etc. All of these methods have both advantages and disadvantages. For example, the fully implicit method, which solves flow and geomechanical behavior simultaneously, is accurate, but requires a huge computer time. In addition, it is difficult to utilize existing flow simulators and geomechanics simulators in this method. Meanwhile, the explicit method does not require much computational time, but is not accurate since the geomechanical behavior is predicted without being reflected enough in flow simulation. The iterative method is accurate because geomechanical information and flow information is transferred to each other until the flow performances become consistent with geomechanical behavior. This method, however, requires considerable computer time. Therefore, we conducted this research seeking for a new method coupling fluid flow with geomechanics that enables the accurate prediction in a reasonably short computer time.