Thermophysical and mechanical properties of granite and its effects on borehole stability in high temperature and three-dimensional stress.
When exploiting the deep resources, the surrounding rock readily undergoes the hole shrinkage, borehole collapse, and loss of circulation under high temperature and high pressure. A series of experiments were conducted to discuss the compressional wave velocity, triaxial strength, and permeability of granite cored from 3500 meters borehole under high temperature and three-dimensional stress. In light of the coupling of temperature, fluid, and stress, we get the thermo-fluid-solid model and governing equation. ANSYS-APDL was also used to stimulate the temperature influence on elastic modulus, Poisson ratio, uniaxial compressive strength, and permeability. In light of the results, we establish a temperature-fluid-stress model to illustrate the granite's stability. The compressional wave velocity and elastic modulus, decrease as the temperature rises, while poisson ratio and permeability of granite increase. The threshold pressure and temperature are 15 MPa and 200 °C, respectively. The temperature affects the fracture pressure more than the collapse pressure, but both parameters rise with the increase of temperature. The coupling of thermo-fluid-solid, greatly impacting the borehole stability, proves to be a good method to analyze similar problems of other formations.
Key Laboratory on Deep Geo-Drilling Technology of the Ministry of Land and Resources, China University of Geosciences, Beijing 100083, China.
Yu
0000-0002-0521-4070
Y
Wang
Key Laboratory on Deep Geo-Drilling Technology of the Ministry of Land and Resources, China University of Geosciences, Beijing 100083, China.
Bao-lin
BL
Liu
State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China.
Hai-yan
HY
Zhu
State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China.
Chuan-liang
CL
Yan
Key Laboratory on Deep Geo-Drilling Technology of the Ministry of Land and Resources, China University of Geosciences, Beijing 100083, China.
Zhi-jun
ZJ
Li
Key Laboratory on Deep Geo-Drilling Technology of the Ministry of Land and Resources, China University of Geosciences, Beijing 100083, China.
Zhi-qiao
ZQ
Wang
D000465:Algorithms; D055598:Chemical Phenomena; D019245:Compressive Strength; D055119:Elastic Modulus; D060587:Groundwater / Q000737:chemistry; D006358:Hot Temperature; D055595:Mechanical Phenomena; D008962:Models, Theoretical; D061329:Oil and Gas Fields / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013314:Stress, Mechanical
C007886:granite; D012822:Silicon Dioxide