The Establishment and Evaluation Method of Artificial Microcracks in Rocks

Zhenkai Wu, Xizhe Li, Hanmin Xiao, Xuewei Liu, Wei Lin, Yuan Rao, Yang Li and Jie Zhang
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Zhenkai Wu: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
Xizhe Li: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
Hanmin Xiao: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
Xuewei Liu: Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
Wei Lin: School of Geosciences, Yangtze University, Wuhan 430100, China
Yuan Rao: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
Yang Li: Research Institute of Petroleum Exploration & Development, Beijing 100083, China
Jie Zhang: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China

Energies, 2021, vol. 14, issue 10, 1-12

Abstract: It is necessary to carry out experiments on cores with different degrees of crack development when studying the seepage law of cracked reservoirs and evaluating cracks. The seepage experiment in the laboratory requires cores with different degrees of microcrack development; cores obtained via conventional drilling cannot meet the requirements, and the efficacies and evaluation methods of geological parameters used for artificial cracks are not perfect. In this study, cores are loaded using a triaxial gripper, and cracks are produced by changing the difference of stress; the relationship between the increased rate of permeability and the change in stress concentration is used to evaluate the degree of development of the crack in real time. The angle between the cracks and the maximum principal stress direction, calculated using the Mohr–Coulomb failure criterion, is 20–27.5°, which provides theoretical support for the process of crack creation. The experimental results show that the permeability variation curve shows two obvious turning points, which divide the whole zone into a reduction zone, a slow increase zone, and a rapid increase zone. Through the obtained experimental and evaluation results, a complete system for crack creation and evaluation is established, which can provide strong support for the study of cracked reservoirs.

Keywords: artificial microcrack; triaxial stress; stress difference; permeability (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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