The Application of Dynamic Monitoring Technology in the Sealability Evaluation of Reservoir-Type Gas Storage Facilities: A Case Study of Jidong M UGS

The injection and production operation of underground gas storage (UGS) is characterized by “large-scale injection and withdrawal” and “alternating injection and production”. Its operation characteristics are significantly different from those of oil and gas field development. The cyclic stress changes pose great challenges to the dynamic sealability of traps, wellbores and other components. Establishing a systematic, permanent and dynamic monitoring system during the injection and production process plays a crucial role in ensuring the long-term safe and stable operation of UGS. This paper focuses on the sealability evaluation of reservoir-type UGS. Taking the Jidong M UGS as an example, the deployment of the sealability monitoring system for reservoir-type UGS is carried out. The monitoring mainly includes the sealability of the cap rock, faults and plugged old wells of the UGS, as well as the migration law of internal fluids. The results show that under the current gas injection intensity, the geological body of the UGS has good sealability. However, in some wellbores, the annular space is under pressure due to reasons such as leakage points in the tubing and casing and poor cementing quality. The sealability monitoring system established in this paper can provide a decision-making basis for the formulation of annual injection and production plans and the regulation of production dynamics of reservoir-type UGS. It can also serve as a reference for the sealability monitoring of UGS converted from similar reservoirs.