Characteristics, genetic mechanism, and hydrocarbon accumulation of Cambrian gravity flow in the eastern Gucheng area, Tarim Basin, China

Abstract

The platform margins of Gucheng and Luoxi in the Cambrian are developed on both sides of the eastern Tarim Basin. Based on the analysis of cores, thin sections, and seismic data of Luoxi platform margin slope areas, we systematically studied the formation condition, reservoir characteristics, and favourable accumulation factors of gravity flow. The types of gravity flow include debris flow, high‐density flow, and low‐density flow, and the high‐density flow reservoir is better. Hydrothermal fluids have an active effect on reservoir reconstruction. Six‐phase reefs are developed in the platform margin, and the lithology of the reservoir is algal framework dolomite and granular dolomite. Multi‐phase reefs form an inclined slope. The 3D seismic and geochemical data show that the platform margin reefs have karst unconformity characteristics. The platform margin slope has the requirements of geomorphology and reservoir source, and the total area of slope gravity flow is 5854 km2. The gravity flow in the Gucheng platform margin slope is near the Cheerchen fault zone, and tectonic movement forms the nose‐like structure. The gravity flow is between the source rocks of the Xidashan Formation and the Heituwa Formation. Hydrocarbon generation and caprock are both favourable for hydrocarbon accumulation. Multi‐phase events of hydrothermal fluids are favourable to the reservoir and hydrocarbon charging. Gravity flow is important for oil and gas exploration in the Tarim Basin.