Abstract
Whether qualitative or quantitative, whether macroscopic or microscopic, Predecessors' research on the sealing ability of caprocks is concentrated on the static model of the caprock. A few scholars have also proposed the sealability evaluations of the caprock dynamic evolution process, they are all aimed at the dynamic evolution of geological historical periods, and there are few studies on the sealability of gas storage caprocks under periodic injection and production. In this paper, the characteristics of stress and strain under alternating loads of rock and non-rock materials are investigated and experimentally studied to clarify the law of fatigue failure of gas storage caprocks under periodic injection-production. The results show that it is possible that the microcracks may develop and propagate in the rock after the gas storage has experienced many periodic injections and productions, when the stress is far less than the rock strength limit, And then a macroscopic deformation is formed. The accumulated plastic deformation of the rock will increase, and the plastic deformation rate will gradually decrease, as the number of injection and production increases.
Highlights
The caprock's plugging capacity refers to the ability of the gas storage to prevent natural gas from escaping, and it controls the vertical distribution, abundance and working pressure of natural gas in the gas storage
Taking the capillary sealing mechanism and hydraulic sealing mechanism of caprocks proposed by Watts in the United States in 1987 as a symbol [1], the sealing mechanism of caprocks and faults was systematically studied and qualitatively evaluated
In 1996, Lu Yanfang and others proposed the overpressure sealing mechanism and the hydrocarbon concentration sealing mechanism [4], and established corresponding displacement pressure, effective stress and tensile strength, abnormal pore fluid pressure and diffusion coefficient according to different sealing mechanisms
Summary
The caprock's plugging capacity refers to the ability of the gas storage to prevent natural gas from escaping, and it controls the vertical distribution, abundance and working pressure of natural gas in the gas storage. Fu Guang et al divided the levels according to the size of influence through the micro and macro aspects, and discussed the method of comprehensively evaluating the sealing ability of the cap layer itself [13]. Scholars such as Sun Mingliang calculated the lithology, thickness and displacement pressure of the caprocks of more than 40 gas reservoirs in my country, and established the evaluation criteria for the caprocks of medium and high-efficiency gas reservoirs [14]. The root cause of the failure [17]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
