Micro-nano-scale Stimulation of Coalbed Methane Reservoir: Experimental
Hydraulic Fracturing and Pore Connectivity
Abstract
The role of micro-nano-scale stimulation of coalbed methane (CBM)
reservoir is to open the fracture and pore channels, improve gas
desorption and migration capabilities, and thereby increase CBM
production capacity. Based on hydraulic fracturing simulation
experiments, combined with liquid nitrogen absorption (LNA) and mercury
intrusion porosity (MIP) measurements, the micro-nano-scale pore
structure of coal before and after hydraulic fracturing stimulation in
coal reservoirs was studied. It is found that significant changes in the
number of pores in different pore sizes are the main reason for the
changes in coal pore volume (PV) and pore specific surface area (PSSA)
after hydraulic fracturing. the micro-nano-scale pore stimulation of
hydraulic fracturing includes two forms of pore fragmentation and pore
deformation, the coal with larger elastic modulus is mainly manifested
as brittle crush. Moreover, larger in-situ stress will inhibit pore
fracture and expansion, and even cause further compression of pores.