The Sinian oil and gas accumulation condition and favorable exploration zone in the Luzhou paleo-uplift area, Sichuan Basin

The Luzhou paleo-uplift is one of the three paleo-uplifts in the Sichuan Basin, and it is also an important natural gas exploration area. The previous studies that have been conducted in the Indosinian paleo-uplift indicate controlling effects on the Permian and Triassic gas reservoirs. However, there are limited studies on the tectonic evolution of the Luzhou paleo-uplift and its controlling effect on the Sinian-Cambrian accumulation. Based on the comprehensive data used during this study, such as seismic, regional geology, and drilling data, the vertical evolution and paleo-tectonic characteristics of the Luzhou paleo-uplift at different tectonic periods were analyzed. The controlling effects of the tectonic evolution of the Luzhou paleo-uplift on the Sinian-Cambrian reservoir accumulation were systematically investigated. Research suggests that the evolution process of the paleo-uplift in Luzhou has gone through four stages: the embryonic stage before the deposition of the Z2dn3 period of the Sinian, the subsidence stage from the Z2dn3 of the Sinian to the pre-deposition stage of the Permian, the Permian to Triassic uplift stage, and the Paleogene to present adjustment and shaping stage. The embryonic stage of the Luzhou paleo-uplift controlled the sedimentary facies and high-quality reservoir distribution of the Dengying Formation. The strong subsidence period controlled the distribution of high-quality hydrocarbon source in the Cambrian. The uplift and formation period adjusted the formation and distribution of early oil reservoirs and late gas reservoirs. The Dengying Formation of the Sinian System is the most favorable exploration layer in the Luzhou paleo-uplift, with two reservoir formation modes developed: self-generation and self-storage and reverse lateral migration. Luzhou-Chongqing, Southwest Weiyuan of Dengying Formation and Longwangmiao Formation are two potential favorable natural gas accumulation zones in the study area.