Research and application of stress disturbance fracturing technology in complex formations in Guizhou Province

Abstract

Guizhou has many coal seams, thin coal seams, many gangues, and rapid lithology changes. Its complex strata characteristics increase the difficulty of fracturing CBM wells. Taking coalbed methane well in Jinjia Coal Mine as an example, we research the risk of complex formation fracturing and fracturing technology, and explore the adaptability of secondary pump-stop fracturing technology under stress disturbance. Engineering practice show that the lithology of coal measures in Jinjia Coal Mine has complex changes, and the lithology can be divided into 5 combination modes; multi-coal and multi-layered coal seams adopt methods such as “avoidance, expansion, selective injection, continuous injection, and directional perforation”, which can reduce the difficulty of fracturing construction. Multi-seam combined layer fracturing and multi-layer coal seam fracturing reform adopted the secondary stop pump fracturing technology, promoted the formation stress redistribution and fracture diversion, and improved the effect of reservoir fracturing reform; two coalbed methane wells in the study area implemented a secondary pumping-off fracturing process. The fracturing construction curve, pressure changes after pumping-off, and gas production effect all show that the fracturing process has a better effect on reservoir reconstruction.

Keywords

• hydraulic fracturing
• complex formation
• coalbed methane (cbm)
• perforation
• secondary pump shutdown
• reservoir reform