Quantitative study of the influence of organic-rich and natural fracture-rich regions on shale gas production

Abstract

Abstract Natural fractures and organic matter are randomly and unevenly distributed in shale gas reservoirs. The presence of organic-rich and natural fracture-rich regions causes the simulation results of the multi-continuum model to exhibit deviations from the real gas flow process. This paper presents a multi-continuum, discrete fracture model that captures the discontinuous nature of kerogen and natural fractures. The mathematical model describes the collision-weighted gas flow in organic matrix pores, inorganic matrix pores, and natural fractures by use of the unified flow model. The influence of organic matter and natural fractures on shale gas production is then quantitatively investigated. We find that Knudsen diffusion plays a more important role in shale gas flow than the viscous flow mechanism. Good communication between hydraulic fractures and natural fracture-rich regions can greatly improve gas production.