Abstract:
Through analyzing the geological characteristics of shale gas, this paper discussed the controlling factors of shale gas accumulation in Yichang area of western Hubei. Based on the tectonic evolution characteristics of Huangling uplift, the evolution of Yichang area could be divided into three stages:formation of rigid basement, sedimentation of overlying strata and transformation by uplifting. Under the control of tectonic evolution, three sets of shale, i.e., Sinian Doushantuo Formation, Cambrian Niutitang Formation and Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in Yichang area, mainly developed in relatively deep water sedimentary environment and had the same depositional setting and composition characteristics with Doushantuo Formation, Qiongzhusi Formation and Longmaxi Formation in Sichuan Basin and material conditions for shale gas formation. Further, based on analyzing the discovered shale gas reservoir, this paper investigated the key control role of Huangling uplift in shale gas accumulation in Yichang area of western Hubei from the aspects of preservation conditions and thermal evolution process. In Yichang area of western Hubei, the ancient blind rigid basement had the characteristics of early formation, wide distribution, strong compression resistance, late and long-duration uplifting, and the ancient shale in the overlying Cambrian, Sinian and Upper Ordovician-Lower Silurian strata had short buried time, relatively low degree of thermal evolution, stable tectonic structure and good preservation condition, which provided favorable geological conditions for shale gas accumulation.