Heterogeneities of seepage pore and fracture of high volatile bituminous coal core: Implications on water invasion degree

High volatile bituminous coal (HVBC) reservoirs are now regarded as one of the most important targets for coalbed methane (CBM) exploration and development in northwestern China. Water invasion during coalbed methane reservoir fracturing can induce water blockage damage, leading to decreased relative permeability of gas and reduced production of CBM well. To study the influences of heterogeneities of seepage pore and fracture on water invasion degree (WID), water flooding experiment using HVBC core was conducted to simulate water invasion; magnetic resonance imaging and gray calculation were applied to quantitatively determine WID; heterogeneous parameters of seepage pore and fracture were extracted based on micro-CT and fractal characterization; finally implications of seepage pore and fracture heterogeneities on WID were discussed, and water invasion mechanism was analyzed.