Study on variation law of coal disturbance stress in hydraulic fracturing test

Abstract

In order to explore the variation of disturbance stress in the coal seam around the fracturing borehole in the process of hydraulic fracturing, taking the 1703 coal face of Junlian Jinzhong Coal Mine Company as the test site, on the basis of determining the relevant hydraulic fracturing parameters, KSE-2-1 mine intrinsic safety digital display borehole stress meter is used to monitor the variation of disturbance stress in coal seams at different distances around the fracturing borehole during fracturing. The field test results show that when coal cracking occurs in the process of hydraulic fracturing, the water injection pressure will decrease significantly, and the unit water injection will increase to a certain extent; in the process of hydraulic fracturing, the transmission of disturbance stress formed by fracturing fluid in coal seam is mainly attenuation; at the same time, within the influence range of hydraulic fracturing, the stress change in the coal seam mainly includes three stages: original stress stage, stress response stage and stress stabilization stage, and the change of disturbance stress in the coal seam in the stress response stage rises in a wave.

Keywords

• hydraulic fracturing
• disturbance stress
• variation
• water injection pressure
• unit water injection