Quantitative Evaluation Method for Gas Loss in Underground Natural Gas Storage Reconstructed from Abandoned Gas Reservoirs

Natural gas loss inevitably occurs during gas injection and production operation in underground gas storage. At present, the study of gas loss is only in the qualitative description stage and cannot meet the quantitative evaluation requirements for economical gas storage. Combining the theory of inventory analysis and the experimental study of the injection-production mechanism and aimed at the phenomena of microseepage, dissolution diffusion, abnormal gas leakage and macroscale gas leakage in the process of injection and production of underground natural gas storage, gas loss evaluation mathematical models are established to quantitatively evaluate the gas loss of underground natural gas storage. The results show that the gas loss in the macrodisplacement process is the main component of geological gas loss in gas storage, which decreases with increasing injection-production cycles. On this basis, a quantitative evaluation method for the natural gas loss of gas reservoir-type gas storage is established, and the accuracy and reliability of the method are verified by the gas loss calculation results of the Banzhongnanbei (BZNB) underground natural gas storage. The validation results show that the calculation error is very small, meeting the requirements of gas storage operation accuracy and providing high application value. This calculation method can effectively reduce the loss of natural gas in gas storage, provide an early warning of leakage risk, and improve the economic benefits and injection-production safety of gas storage.