Dynamics of Multi-Continuum/Discrete-Fracture Interactions of Nonlinear Gas Transport in Shale

Advances in multistage fracturing combined with horizontal drilling have made this technique the driving force for the recent spectacular success in shale gas development and production. In this paper, a hierarchical approach integrating discrete fracture networks with multi-continuum concept is proposed to model various coupling mechanisms of gas nonlinear transport in shale. The hybrid model is composed of three continuum layers: organic matter, inorganic matter and micro-fractures in matrix which are treated as a continuum medium, and the discrete fractures are embedded into the micro-fracture-continuum. The extended finite element method is employed to decouple the mesh conformity between the mesh of media and the discrete fractures. The results of long-term well-performance dynamics are used to show the power and flexibility for simulating the multi-continuum/discrete-fracture interactions during gas transport in shale. The effects of fracture geometry and coupling flow mechanisms on gas production are also analyzed in this paper.