Research on In-situ Stress Testing of Deephole Cores from Earthquake Faults Using the Inelastic Strain Recovery Method1

International Conference on Manufacturing Technology, Materials and Chemical Engineering

机械制造;材料科学;化学工业

You, Z.^1 ; Lu, Hong^1

Physical Science and Technology College, Yichun University, Xuefu Road, Yuanzhou District, Yichun, Jiangxi

336000, China^1

关键词: Geologic conditions;    Hydraulic fracturing methods;    In-situ stress measurement;    Inelastic deformation;    Measurement methods;    Scientific drilling;    Viscoelastic bodies;    Wenchuan Earthquake;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/392/6/062077/pdf
DOI  :  10.1088/1757-899X/392/6/062077

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

The Wenchuan Earthquake Fault Scientific Drilling Project, a scientific drilling project that first responded to the Earthquake, performed deep 3D in-situ stress measurements using the inelastic strain recovery of core method for the first time under conditions whereby the borehole breakout method and hydraulic fracturing method could not be applied. The inelastic deformation of the deephole cores under the action of 3D stresses was simulated based on the inelastic strain recovery of viscoelastic body theory and core testing theory and the direction & magnitude of 3 major stresses were calculated under the precondition of homogeneous isotropy. In the field laboratory of the WFSD Project, the testing system developed was used to test the normal strain of inelastic recovery strain of deephole cores in 6 independent directions and determine the direction & magnitude of 3D in-situ stresses of the test points. In order to verify the effectiveness of the inelastic strain recovery method, an analysis was given into the testing result of #1 hole of the WFSD Project, which perfectly matches the result obtained by means of focal mechanism solution and other stress measurement methods, indicating that the inelastic strain recovery method is reasonable and reliable and is more applicable under complex geologic conditions whereby other in-situ stress testing methods cannot be applied. The method provides a new means for performing in-situ stress measurements using the core method under large-depth drilling conditions.