四川盆地中部蓬莱—高磨地区下寒武统沧浪铺组一段颗粒滩差异沉积及其控制因素OA

The production of high-yield industrial gas flow from the grain bank facies dolomite reservoir of the first Member of Canglangpu Formation(Cang 1 Member)in the Penglai area of the central Sichuan Basin indicates its significant exploration potential,but the differential sedimentation characteristics and controlling factors of the grain banks remain unclear,which restricts the exploration deployment.Based on core,thin section and logging data,this paper studies the basic sedimentary characteristics and differences in vertical and lateral development and areal distribution of grain banks,and then discusses the main controlling factors and models of differential sedimentation of grain banks in the Penglai-Gaomo area.The following results are obtained.First,the grain banks of Cang 1 Member in the Penglai-Gaomo area are mainly composed of oolitic limestone and oolitic dolomite.There are several upward shallowing sequences in the vertical direction,and the lateral distribution is controlled by paleogeomorphology.Second,the grain banks in the Penglai area are highly developed with good lateral continuity,while those in the Gaomo area are thin and discontinuous laterally.Third,the differential sedimentation of Cang 1 Member grain banks in the Penglai-Gaomo area are under the joint control of sea level eustacy,paleogeomorphologic pattern and terrigenous clastic input,with sea level eustacy controlling the stacking patterns of grain banks,paleogeomorphologic pattern dominating the differential areal distribution of grain banks,and terrigenous clastic input controlling the development degree of grain banks.Fourth,in the Penglai area,great tectonic uplift,elevated paleogeomorphology,and distance from terrigenous sources favors the development of thick and continuous grain banks;in the Gaomo area,however,relatively low paleogeomorphology and strong terrigenous clastic dilution lead to the formation of thin and isolated grain banks.In conclusion,the research results can provide new geological basis for hydrocarbon exploration in the dolomite reservoirs of grain banks facies in the deep Canglangpu Formation of the Sichuan Basin.