Regional unconformities and their controls on hydrocarbon accumulation in Sichuan Basin, sW China  

作　　者：YANG Weij WEI Guoqi WU Saijun XIE Wuren JIN Hui ZENG Fuying HAO Cuiguo BAI Zhuangzhuang SU Yiqing LI Rong 

机构地区：[1]PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China [2]Key Laboratory of Gas Reservoir Formation and Development,CNPC,Langfang 065007,China

出　　处：《Petroleum Exploration and Development》2023年第3期573-587,共15页石油勘探与开发（英文版）

基　　金：Supported by the National Natural Science Foundation Project of China(U22B6002);Prospective Basic Technology Research Project of PetroChina(2021DJ0605).

摘　　要：Based on outcrop,seismic and drilling data,the main regional unconformities in the Sichuan Basin and their controls on hydrocarbon accumulation were systematically studied.Three findings are obtained.First,six regional stratigraphic unconformities are mainly developed in the Sichuan Basin,from the bottom up which are between pre-Sinian and Sinian,between Sinian and Cambrian,between pre-Permian and Permian,between middle and upper Permian,between middle and upper Triassic,and between Triassic and Jurassic.Especially,16 of 21l conventional(and tight)gas fields discovered are believed to have formed in relation to regional unconformities.Second,regional unconformity mainly controls hydrocarbon accumulation from five aspects:(1)The porosity and permeability of reservoirs under the unconformity are improved through weathering crust karstification to form large-scale karst reservoirs;(2)Good source-reservoir-caprock assemblage can form near the unconformity,which provides a basis for forming large gas field;(3)Regional unconformity may lead to stratigraphic pinch-out and rugged ancient landform,giving rise to a large area of stratigraphic and lithologic trap groups;(4)Regional unconformity provides a dominant channel for lateral migration of oil and gas;and(5)Regional unconformity is conducive to large-scale accumulation of oil and gas.Third,the areas related to regional unconformities are the exploration focus of large gas fields in the Sichuan Basin.The pre-Sinian is found with source rocks,reservoir rocks and other favorable conditions for the formation of large gas fields,and presents a large exploration potential.Thus,it is expected to be an important strategic replacement.

关 键 词：UNCONFORMITY large gas filed Sichuan Basin karst reservoir hydrocarbon accumulation control exploration potential 

分 类 号：P618.13[天文地球—矿床学]