Study on the strain response characteristics of coal and rock borehole walls under high-pressure gas fracturing
KONG Zixing
MA Yankun
YANG Fade
WANG Xiaoqi
GONG Liqiang
JIANG Mingfeng
Abstract：There has been a lack of precise methods for monitoring and evaluating the entire process of gas fracturing.However,strain monitoring can effectively record the real-time initiation and propagation of cracks.By studying the strain response of borehole walls during high-pressure gas impact,the relationship between crack formation and strain response during the fracturing process can be clarified,enabling the identification of the optimal fracturing angle.A true triaxial experimental system for high-pressure gas fracturing of coal and rock was used,and experiments were conducted at five different impact angles(0,30,45,60,90°)to investigate crack morphology,pressure curves,and strain response characteristics of the borehole walls.The experimental results revealed that:①As the impact angle increased,the crack morphology of coal and rock exhibited a pattern that was initially complex but later became simpler.②The gas pressure during the fracturing process passed through four stages:an increase,a sharp drop,accumulation,and steady release.③The strain data for the borehole walls were predominantly tensile,and the strain curve displayed two distinct peaks:the first peak occurred 0.1 seconds after the pressure curve reached its peak,coinciding with the formation of the main crack;the second peak was generally associated with the propagation and expansion of the main crack.④When the impact angle was 45°,a more complex crack network tended to form within the specimen,resulting in the most effective fracturing.
Keywords：gas fracturingborehole wall strainimpact anglecrack morphologygas pressure response
Publication Date：2024-10-10
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 105-111 )