A new method for multi-factor capacity review of underground gas storage under complex geological conditions

The review of underground gas storage（UGS） capacity is influenced by multiple factors. Optimizing this capacity is crucial for achieving global optimization of UGS design parameters. The W23 UGS in Dongpu sag serves as a case study to explore the effects of formation water intrusion, salt deposition, stress sensitivity, and produced liquid on storage capacity utilization. A new model for reviewing the storage capacity, tailored to the specific conditions of W23 UGS, was developed and its feasibility was assessed. The results indicate that the W23 UGS exhibits low porosity and permeability, strong vertical heterogeneity, but weak lateral heterogeneity, characteristic of a weak edge water-driven gas reservoir. Factors such as the original gas storage volume, salt deposition, stress sensitivity, vertical production degree, formation water invasion, and produced liquid significantly impact the storage capacity of W23 UGS. The final check of the effective gas storage volume was calculated to be 3 679.51×104 m³, which is 3.9% lower than the originally estimated volume. Regionally, the effective volume after the first-stage review was 3 013.47×104 m³, representing 97.3% of the original storage volume. Meanwhile, an additional effective volume of 666.04×104 m³, accounting for 91.1% of the original volume, was identified. The main reasons for the reduced review results include the impacts of stress sensitivity, formation water intrusion, and vertical utilization, which collectively led to a decrease in the effective gas storage volume.