首页|Hydraulic fracturing behaviors of shale under coupled stress and temperature conditions simulating different burial depths

Hydraulic fracturing behaviors of shale under coupled stress and temperature conditions simulating different burial depths

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Fracture propagation in shale under in situ conditions is a critical but poorly understood mechanical pro-cess in hydraulic fracturing for deep shale gas reservoirs.To address this,hydraulic fracturing experi-ments were conducted on hollow double-wing crack specimens of the Longmaxi shale under conditions simulating the ground surface(confining pressure σcp=0,room temperature(Tr))and at depths of 1600 m(σcp=40 MPa,Ti=70 ℃)and 3300 m(σcp=80 MPa,high temperature Ti=110 ℃)in the study area.High in situ stress was found to significantly increase fracture toughness through constrained microcrack-ing and particle frictional bridging mechanisms.Increasing the temperature enhances rather than weak-ens the fracture resistance because it increases the grain debonding length,which dissipates more plastic energy and enlarges grains to close microdefects and generate compressive stress to inhibit microcrack-ing.Interestingly,the fracture toughness anisotropy in the shale was found to be nearly constant across burial depths,despite reported variations with increasing confining pressure.Heated water was not found to be as important as the in situ environment in influencing shale fracture.These findings empha-size the need to test the fracture toughness of deep shales under coupled in situ stress and temperature conditions rather than focusing on either in situ stress or temperature alone.

Hydraulic fracturingFracture toughnessShaleAnisotropyDeep rock mechanics

Qin Zhou、Zheming Zhu、Wei Liu、Huijun Lu、Zidong Fan、Xiaofang Nie、Cunbao Li、Jun Wang、Li Ren

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MOE Key Laboratory of Deep Earth Science and Engineering,College of Architecture and Environment,Sichuan University,Chengdu 610065,China

Downhole Operating Company,CNPC Chuanqing Drilling and Exploration Engineering Co.,Ltd.,Shenzhen 518060,China

School of Architecture and Civil Engineering,Xihua University,Chengdu 610065,China

Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,Shenzhen University,Shenzhen 518060,China

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National Natural Science Foundation of China

No.12172240

2024

10.1016/j.ijmst.2024.06.005

矿业科学技术学报(英文版)
中国矿业大学

矿业科学技术学报(英文版)

CSTPCDEI
影响因子：1.222
ISSN：2095-2686
年,卷(期)：2024.34(6)
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