天然气工业2018，Vol.38Issue(1)：30-38,9.DOI:10.3787/j.issn.1000-0976.2018.01.004
四川盆地中二叠统茅口组天然气大面积成藏的地质条件
Geological conditions for massive accumulation of natural gas in the Mid-Permian Maokou Fm of the Sichuan Basin
摘要
Abstract
In the past few years,a number of high-productivity gas wells were drilled in the Mid-Permian Maokou Fm in the northwestern and central parts of the Sichuan Basin.This set of strata appears to have bright prospects in natural gas exploration.To determine if it has necessary geological conditions for the massive accumulation of natural gas,we conducted a study in three aspects,i.e.conditions of hydrocarbon source rocks,distribution of grain beaches,and distribution and origin of weathered crust karst reservoirs.The following findings were obtained.First,the Maokou Fm gentle-slope grain beaches are distributed extensively in the areas to the west of GuangyuanGuang'an-Chongqing,laying a reliable geological foundation for the formation of reservoirs.Second,the global sea-level fall led to the formation of regional erosion surfaces,which eventually promoted the formation of massive karst reservoirs.Third,three major sets of hydrocarbon source rocks (Lower Silurian Longmaxi Fm,Mao-1-Mao-2c,and Upper Permian Longtan Fm) and the weathered crust karst reservoir of Maokou Fm formed a "sandwich-type" source-reservoir assemblage,which is the key to the massive accumulation of natural gas.On this basis,the gas enrichment conditions in the Maokou Fm were analyzed,and favorable exploration orientation and targets were proposed.In conclusion,the Maokou Fm in the basin has necessary geological conditions for the massive accumulation of natural gas.Besides,the erosion palaeogeomorphology and later strike-slip faults reworked and controlled the distribution of large fractures and cavities in the study area,and the combination of grain beaches,weathered crust karsts,and strike-slip faults controlled the favorable zones for the enrichment and high-productivity of natural gas.Moreover,the Gaoshiti-Moxi area in the central Sichuan Basin,where strike-slip faults are developed and there are favorable gas accumulation conditions in the Maokou Fm,is an ideal option for scale natural gas exploration.关键词
四川盆地/中二叠世/茅口组/天然气大面积成藏/地质条件/颗粒滩/风化壳岩溶/源—储组合/勘探区Key words
Sichuan Basin/Mid-Permian/Maokou Fm/Massive accumulation of natural gas/Geologic conditions, Grain beach/Weathered crust karsts/Source-reservoir assemblage/Exploration zone引用本文复制引用
汪泽成,江青春,黄士鹏,周慧,冯庆付,戴晓峰,鲁卫华,任梦怡..四川盆地中二叠统茅口组天然气大面积成藏的地质条件[J].天然气工业,2018,38(1):30-38,9.基金项目
国家科技重大专项“下古生界—前寒武系碳酸盐岩油气成藏规律、关键技术及目标评价”(编号:2016ZX05004-001). （编号:2016ZX05004-001）
