Geology and Development of the Xiangguosi Dolomite Storage

Abstract

The Xiangguosi gas storage is located 60 km north of Chongqing City, at 900 m above sea level. It is a high-steep anticline with a 26 km long axis, a 1.4 km short axis, and a closed area of 29.24 km². The reservoir is dominated by the brecciated dolomite of the second member of the Carboniferous Huanglong Formation (C₂hl₂), with a formation thickness of about 10 m and an average well test permeability of 300 mD. The upper Liangshan Formation is the cap layer, and the Lower Silurian shale is the septal layer, forming a good reservoir-cap combination. The original formation pressure of the Xiangguosi gas reservoir is 28.7 MPa, and 98% of the natural gas is methane. The geological reserve is 43.90 × 10⁸ m³. Since its production and development in 1977, the cumulative gas production has reached 40.24 × 10⁸ m³, the remaining geological reserve is 3.66 × 10⁸ m³, the degree of geological reserve production is 91.66%, the cumulative condensate production is 1903 m³, and the reservoir water is 110 m³. Interference testing indicates that the gas reservoir wells have good connectivity. This provides a good material basis for rebuilding the reservoir as gas storage.