Dynamic Evaluation of Sealing and Site Optimization for Underground Gas Storage in Depleted Gas Reserve: A Case Study

In the post-epidemic economic recovery background, under the influence of the international situation brought by the Russia-Ukraine conflict, the world is facing a significant rebound in total energy consumption. In order to seek a smooth transition for national energy low-carbon transformation, it is urgent that research be conducted on the trap dynamic sealing capacity evaluation and site optimization for underground storage in depleted gas reserves. Based on the geological data of Block S in Northeast China, combined with a dynamic acoustic test and a static triaxial test, a rock mechanical property model for wells is established, and the stress model of the underground storage in depleted gas reserves before construction is inverted. The sealing of the cap rock and faults in the underground gas storage is evaluated from both static and dynamic perspectives. The results show that the maximum horizontal principal stress of the cap rock and reservoir before construction is distributed between 48-76 MPa and 50-85 MPa, respectively. The reservoir of the Yingcheng Formation has strong stratigraphic mechanical strength and can be used as the main space for underground gas storage. The global cap rock shear safety factor is between 0.7-0.9, and the fault slip factor is only 0.1, indicating that this reservoir has strong dynamic closure sealing and is suitable for construction, thereby realizing the dynamic evaluation of sealing and site optimization for underground gas storage in a depleted gas reserve, providing a guarantee for the safe and stable operation of its subsequent expansion, multi-cycle injection, and production.