Role of paleouplift in the scale formation of intra-platform carbonate mound-bank body reservoirs in the Sichuan Basin

Intra-platform carbonate mound-bank body reservoirs is an important type of oil and gas reservoirs in the Sichuan Basin, and paleouplift plays an important role in the scale formation process of scale intra-platform mound-bank body reservoir. So far, however, the control action of paleouplift on the formation and distribution of intra-platform mound-bank body reservoirs has not been understood clearly enough, which restricts the oil and gas exploration progress of this type of reservoirs. In order to provide the basis for oil and gas exploration deployment, this paper analyzes the formation and evolution of four paleouplifts developed in the cratonic stage of the Sichuan Basin. On this basis, the genetic mechanisms and characteristics of scale intra-platform mound-bank body reservoirs are studied, and the characteristics and distribution of large-scale intra-platform reservoirs in the main series of strata are analyzed. And the following research results were obtained. First, the four paleouplifts developed in the Sichuan Basin plays an important constructive role in the formation of scale intra-platform mound-bank body reservoirs. Their control actions mainly include sedimentation and diagenesis. Along with the sea level change, they control the sedimentation scale and distribution range of intra-platform mound-bank body. They control the interlayer karstification and quasi-syngenetic dolomitization of intra-platform mound-bank body. And together with the late tectonic movement, they control the weathering crust karstification and fracturing of intra-platform mound-bank body. Second, Gaoshiti-Moxi paleouplift mainly controls the formation of the large-scale intra-platform mound-bank body reservoirs in the Sinian Dengying Formation and the Cambrian Longwangmiao Formation, Leshan-Longnüsi paleouplift mainly controls the formation of the scale intra-platform mound-bank body reservoir in the Cambrian Xixiangchi Formation and the Carboniferous Huanglong Formation, while Luzhou and Kaijiang paleouplifts mainly control the formation of the scale intra-platform mound-bank body reservoirs in the Triassic Jialingjiang Formation and Leikoupo Formation. Third, six sets of scale intra-platform reservoirs are developed in the Sichuan Basin. The intra-platform mound-bank body reservoirs of Dengying Formation and Longwangmiao Formation are mainly distributed in the core of paleouplift, and the other four sets are mainly distributed in the slope of paleouplift. In conclusion, these research results provide the geological basis for the prediction of scale intra-platform mound-bank body reservoirs in the Sichuan Basin and they are of important theoretical and practical significance. © 2021, Natural Gas Industry Journal Agency. All right reserved.