石油实验地质2025，Vol.47Issue(4)：731-741,11.DOI:10.11781/sysydz2025040731
四川盆地南部中三叠统雷口坡组岩相古地理与常规—非常规双领域勘探意义
Lithofacies paleogeography of Middle Triassic Leikoupo Formation in the southern Sichuan Basin and its implications for conventional and unconventional dual-domain exploration
摘要
Abstract
The Leikoupo Formation of the Middle Triassic is one of the earliest strata for oil and gas exploration in the Sichuan Basin,but its exploration has long been limited to scattered small gas fields.Recent studies reveal that the Leikoupo Formation holds dual prospects for marine conventional and unconventional oil and gas reser-voirs,but the existing paleogeographic pattern is inadequate for the new exploration needs.This study focused on the Leikoupo Formation in the southern Sichuan Basin.Based on the detailed analysis of sedimentary facies in outcrops and drill cores,the lithofacies paleogeography was reconstructed and the sediment and reservoir develop-ment patterns were studied.The sedimentary environment types in the Middle Triassic Leikoupo Formation of the southern Sichuan Basin included platform tidal flats,tidal shoals,shelf bays,and saline lagoons.During the transgression period(members 1 and 3 of the Leikoupo Formation),relatively high-energy marine conditions favored the development of high-energy shoal facies and organic-rich mudstone or marl.During the regressive period(members 2 and 4 of the Leikoupo Formation),the energy was relatively lower,favoring the development of dolomite and evaporite successions.The development of conventional carbonate rock reservoirs in the Leikoupo Formation of the southern Sichuan Basin was primarily controlled by the paleogeomorphic pattern.The combined effects of wave and tidal actions led to the extensive distribution of thin shoal-facies dolomite reservoirs.The transgression during the depositional period of member 3 of the Leikoupo Formation played a significant role in the formation of unconventional reservoirs of organic-rich mudstone or marl.It not only altered the original paleo-geomorphic pattern but also transported organic-rich clastic materials from the Badong Formation into the interior of the Upper Yangtze Craton.Under intense evaporation during the later stages,intersalt hydrocarbon reservoirs with a"salt rock and marl"cycle were formed.The paleogeographic reconstruction in both conventional and unconventional domains of the Leikoupo Formation in the southern Sichuan Basin not only reveals a new explora-tion area for marine intersalt unconventional resources,but also confirms the favorable conditions for the develop-ment of high-quality source rocks within the formation.关键词
非常规泥灰岩储层/潮缘滩白云岩储层/岩相古地理/雷口坡组/四川盆地Key words
unconventional marl reservoir/tidal shoal dolomite reservoir/lithofacies paleogeography/Leikoupo Formation/Sichuan Basin分类
能源科技引用本文复制引用
宋晓波,孙诗,陈安清,苏成鹏,刘勇,孙娜,王泽宇,李雯,王宪峰,黄光辉..四川盆地南部中三叠统雷口坡组岩相古地理与常规—非常规双领域勘探意义[J].石油实验地质,2025,47(4):731-741,11.基金项目
国家自然科学基金项目(U24A20591、42272132)和中国石化西南油气分公司勘探开发研究院项目(34450000-22-ZC0607-0038)联合资助. （U24A20591、42272132）
