裂缝型气藏改建储气库地质可行性分析-以铜锣峡储气库为例

Underground gas storage is currently the most important method for natural gas storage and peak shaving in the world. The geological conditions in China are very complex, and the integrity of the gas storage geological body is a crucial foundation for the preliminary evaluation of gas storage facilities. Based on the geological characteristics analysis of the Tongluoxia gas storage facility in Chongqing, a geological feasibility evaluation approach for transforming fractured gas reservoirs into gas storage facilities has been developed. Research results indicate that the reservoir of the Changxing Formation in the Tongluoxia gas storage facility is composed of limestone, with the main storage space being structural fractures and dissolution fractures, along with a small amount of intergranular dissolved pores and crystal pores. The overlying cap rock of the first member of Feixianguan Formation is primarily composed of mudstone, characterized by dense lithology, small pore throats, and high rock strength, with a significant shear failure factor (0.836) and considerable variability in uniaxial tensile strength, making it a good regional cap rock. The faults within the area have not compromised the integrity of the overlying cover or the trapping structure, indicating a high degree of reliability. The gas dissipation pressure within the study area is 55.907 MPa, while the tensile failure critical pressure of the cap rock is 42.92 MPa, and the shear failure critical pressure is 97.63 MPa. It is inferred that the sealing limit pressure of the gas storage facility is 42.92 MPa, and the operational upper pressure of the gas storage facility should not exceed this value. Overall, the cap rock of the Tongluoxia gas storage facility exhibits good sealing properties, a high degree of reliability in fault integrity, low risks of gas dissipation, and weak stress sensitivity in the reservoir, making it suitable for conversion into a gas storage facility.