Based on analysis of outcrop, drilling, logging and seismic data, and geotectonic background, the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan Basin were reconstructed, and the petroleum geological significance of the lithofacies paleogeography and paleokarst geomorphology were discussed. The Maokou Formation is divided into 3 long-term cycles, namely LSC1, LSC2 and LSC3, which correspond to the Member 1, Member 2 and Member 3 of the Maokou Formation, respectively. Controlled by the extensional structure caused by opening of the Mianlue Ocean in the north margin of the upper Yangtze blocks and basement faults produced by mantle plume uplifting, the area had tectonic differentiation in NWW and NE, and sedimentary basement took on episodic settlement from north to south, as a result, the sedimentary systems of Member 1 to Member 3 gradually evolved from carbonate platform to platform-slope-continental shelf. According to the residual thickness, paleokarst geomorphologic units such as karst highland, karst slope and karst depression at different stages were reconstructed. The karst geomorphological units were developed successively on the basis of sedimentary geomorphology. Sedimentary facies and paleokarst geomorphology are of great significance for oil and gas accumulation. The Maokou Formation in northwestern Sichuan has two kinds of most favorable reservoir zone combinations: high energy grain shoal and karst monadnock, platform margin slope and karst slope. Based on this understanding, the planar distribution of the two kinds of reservoir zones were predicted by overlapping the favorable reservoir facies belt with paleokarst geomorphology. The study results provide a new idea and reference for the exploration deployment of the Middle Permian Maokou Formation in the Sichuan Basin.

在分析露头，钻探，测井，地震资料和大地构造背景的基础上，重建了川西北地区中二叠统茅口组的岩相古地理和古岩溶地貌，并对岩相古地理和古岩溶地貌的石油地质意义进行了研究。讨论过。茅口组分为3个长期周期，即LSC1，LSC2和LSC3，分别对应于茅口组的成员1，成员2和成员3。受上扬子地块北缘绵略海洋的开放和地幔柱隆升产生的基底断层引起的伸展构造的控制，该地区在西北和东北具有构造分化，沉积基底从北向北呈间歇性沉降。南，结果，第1到第3成员的沉积体系逐渐从碳酸盐岩台地演化为平台-斜坡-陆架。根据剩余厚度，重建了不同阶段的岩溶高地，岩溶斜坡和岩溶洼地等古岩溶地貌单元。喀斯特地貌单元在沉积地貌基础上相继发展。沉积相和古喀斯特地貌对油气成藏具有重要意义。川西北地区的茅口组有两种最有利的储集带组合：高能颗粒浅滩和岩溶莫纳德克岩，平台边缘斜坡和岩溶斜坡。基于这种理解，通过将有利的储集相带与古岩溶地貌交叠来预测两种储集层的平面分布。研究结果为四川盆地中二叠统茅口组的勘探部署提供了新的思路和参考。