Formation conditions of Sinian–Cambrian large lithologic gas reservoirs in the north slope area of central Sichuan Basin,SW China  

作　　者：WEI Guoqi XIE Zengye YANG Yu LI Jian YANG Wei ZHAO Luzi YANG Chunlong ZHANG Lu XIE Wuren JIANG Hua LI Zhisheng LI Jin GUO Jianying 

机构地区：[1]PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China [2]Key Laboratory of Gas Reservoir Formation and Development,CNPC,Langfang 065007,China [3]PetroChina Southwest Oil&Gas Field Company,Chengdu 610051,China

出　　处：《Petroleum Exploration and Development》2022年第5期963-976,共14页石油勘探与开发（英文版）

基　　金：Chinese Academy of Sciences Strategic Pilot Science and Technology Project(Class A)(XDA14010403);National Science and Technology Major Project(2016ZX05007);PetroChina Science and Technology Project(2021DJ0604,kt2020-01-03)。

摘　　要：Based on analyses of characteristics,hydrocarbon charging history and geological conditions for the formation of Sinian-Cambrian reservoirs in the north slope area of central Sichuan paleo-uplift,the natural gas origin,accumulation evolution,accumulation pattern and formation conditions of large lithologic gas reservoirs have been investigated.Through comprehensive analyses of natural gas composition,carbon and hydrogen isotopic compositions,fluid inclusions,reservoir bitumen,and geological conditions such as lithofacies paleogeography and beach body characterization,it is concluded that:(1)The natural gas in the Sinian-Cambrian of the north slope area is mainly oil cracking gas,and different contribution ratios of multiple sets of source rocks lead to different geochemical characteristics of natural gas in different reservoirs.(2)Although the both Sinian and Cambrian gas reservoirs in this area are lithologic gas reservoirs under monocline background,the former has normal-pressure and the latter has high-pressure.There are three types of source-reservoir-caprock combinations:single source with lower generation and upper reservoir,double sources with lower generation and upper reservoir or with side source and lateral reservoir,double sources with lower generation and upper reservoir or with upper generation and lower reservoir.The Permian-Triassic is the main generation period of oil,Early-Middle Jurassic is the main generation period of oil cracking gas and wet gas,and Late Jurassic-Cretaceous is the main generation period of dry gas.(3)The Sinian-Cambrian system of the north slope area has two favorable conditions for formation of large lithologic gas reservoirs,one is that the large scale beach facies reservoirs are located in the range of ancient oil reservoirs or near the source rocks,which is conducive to the"in-situ"large-scale accumulation of cracked gas in the paleo-oil reservoirs,the other is that the large scale mound-beach complex reservoirs and sealing layers of inter beach tight zones match effecti

关 键 词：lithologic gas reservoir cracking gas accumulation pattern geochemical characteristics Sinian System Cambrian System Sichuan Basin 

分 类 号：P618.13[天文地球—矿床学]