Shale gas/oil is attracting remarkable attention in the world because of their vast technically recoverable reserves. However, it is difficult to predict gas/oil flow behavior in shale gas/oil reservoirs due to their unique features. In general, the dual-porosity/dual-permeability (fracture and matrix) simulator is used for numerical simulation of shale gas/oil reservoirs. In fact, shale gas/oil reservoirs have more complicated structure, and hence, the dual-porosity/dual-permeability model cannot reproduce the gas/oil flow behavior in shale gas/oil reservoirs rigorously. Taking account of this background, a novel reservoir simulator was developed for predicting shale gas/oil flow behavior in this study.

We developed the white oil type simulator that can deal with three-dimensional, three-phase, quadruple-porosity/quadruple-permeability flow behavior. The white oil type simulator enables to account for the deposition of condensate from gas phase and the quadruple-porosity/quadruple-permeability model can reproduce the fluid flow among induced hydraulic fractures, natural fractures, matrices and organic matrices, which may exist in shale gas/oil reservoirs. Furthermore, the embedded discrete fracture model (EDFM) was incorporated into this simulator to express more realistic induced fracture distributions. This method enables to define the domain of each induced fracture regardless of the definition of grid blocks, which results in the construction of a reservoir model with more reliable fracture distributions. After the verification of this simulator with analytical solutions and dual-porosity/dual-permeability commercial simulator, sensitivity studies were conducted, which revealed the importance of considering complex shale structure and the parameters affecting the shale gas/oil production behavior significantly. Through this study, three main conclusions were drawn:

  1. benefits of the quadruple-porosity/quadruple-permeability model,

  2. importance of organic matrices in the development of shale reservoirs and

  3. advantage of embedded discrete fracture model.

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