Characteristics and Controlling Factors of Fluid Interlayer Crossflow through Fractures in Coal Measure Gas Reservoirs: Implication for Enhancing Production

Against the backdrop of implementing integrated hydraulic fracturing on coal measure gas (CMG) reservoirs, fluids can flow through interlayer fractures during drainage stage, resulting in fluid interlayer crossflow (IC). However, its impact on CMG development and the controlling factors remain unclear. This paper employs numerical simulations to investigate these issues. The results indicate that fluid IC through fractures leads to more evenly distributed pressure drops among layers with varying permeabilities. Fluid consistently migrates from a low-permeability layer to a high-permeability layer, resulting in higher production rate from the latter. Additionally, as fluid IC diverts between high- and medium-permeability layers in the early stage of drainage, the production rate of medium-permeability layers tends to increase. In general, fluid IC promotes CMG well production but its impact varies throughout the drainage process. Fluid IC is influenced by both geological and technical factors. Specifically, changes in initial reservoir pressure have a negligible impact on the promotion effect of fluid IC on total production. However, the promotion effect is enhanced as the permeability of high-permeability reservoirs increases, as the distance between fluid IC channel and wellbore increases, and as the permeability, elasticity, and drainage intensity of low-permeability reservoirs decrease. Based on these findings, the implications of fluid IC for CMG efficient development are demonstrated, and suggestions for optimizing the development technology are proposed.Please check and confirm the corresponding author affiliation is correctly identified.The corresponding author affiliation is correct.