Accumulation model of the Sinian-Cambrian shale gas in western Hubei Province, China

Based on the study of a large number of real data of shale gas exploration in the Sinian Doushantuo Formation and the Cambrian Niutitang Formation in western Hubei Province, the theoretical understanding of shale gas accumulation in the Sinian and Cambrian that lithofacies controls carbon, diagenesis controls hydrocarbon and structure controls reservoir is put forward innovatively. The deposition of organic-rich shales in the Sinian Doushantuo Formation and the Cambrian Niutitang Formation were controlled by the rift trough in western Hubei. Sweet spots of organic-rich shales were mainly formed in the transgressive system tract and the early high water-level system tract. The long-term shallow burial in the Sinian and Triassic around the Huangling paleo-uplift provided sufficient time for the oil generation. The Triassic is a short-term and rapid burial period, which is the main peak period of shale gas generation. The rigid basement of paleo-uplift, regional shale cap rock and later thrust nappe structure provided good conditions for the shale gas preservation. Thus, the shale gas accumulation model of the Sinian and Cambrian in western Hubei Province is established, which includes carbon control by deep-water trough, hydrocarbon control by shallow burial of paleo-uplift, reservoir control by paleo-uplift and thrust fault.