川西北地区二叠系茅口组气藏天然气地球化学特征及来源分析  

Geochemical characteristics and source analysis of natural gas in Middle Permian Maokou formation in Northwest Sichuan Province

作　　者：何佳玲 田亚铭[1] 朱祥 袁龙 邓剑 张雷 HE Jialing;TIAN Yaming;ZHU Xiang;YUAN Long;DENG Jian;ZHANG Lei(Chengdu University of Technology,Chengdu 610059,Sichuan province,China;Sinopec Exploration Company,Chengdu 610041,Sichuan province,China)

机构地区：[1]成都理工大学,成都610059 [2]中国石油化工股份有限公司勘探分公司,成都610041

出　　处：《地质找矿论丛》2025年第1期63-72,共10页Contributions to Geology and Mineral Resources Research

摘　　要：近年来,川西北地区中二叠统茅口组天然气勘探获得重大突破,进一步展示了川西北茅口组气藏的良好开发前景。随着勘探深入及相关资料不断丰富,该地区各气田天然气成因及来源不明确的问题亟待解决。为此,在系统整理天然气样品测试分析资料及实验分析的基础上,结合天然气成因判别图及不同层系烃源岩、天然气特征,进行气源、气气对比分析,明确川西北气田茅口组天然气成因类型及其主力源岩。研究结果表明:①川西北地区元坝、九龙山、双鱼石、河湾场、吴家坝及矿山梁气田茅口组天然气中CH 4含量最高,均值为93.64%,重烃C_(2+)含量低,干燥系数均>0.99,属于典型高演化干气,非烃类气体种类较多且各气田中的含量有所差异;各气田天然气中δ^(13 )C有较明显差异。②元坝、九龙山、双鱼石、吴家坝及矿山梁气田天然气属于高成熟过成熟油型气与煤型气的混合气,河湾场气田则为高成熟油型气;川西北地区茅口组天然气处于原油裂解气和干酪根裂解气的交汇处且在各气田中有所差异。③川西北地区茅口组天然气为混源气,元坝及九龙山气田茅口组天然气源于吴家坪组及茅口组烃源岩共同供烃;双鱼石气田除茅口组自身烃源岩供烃外,混有笻竹寺组烃源岩产气;处于断裂发育区的河湾场气田为下部笻竹寺组烃源岩供烃;矿山梁气田以茅口组烃源岩供烃;而吴家坝气田天然气则主要源于茅口组烃源岩,可能存在下伏笻竹寺组烃源岩供烃。In recent years breakthroghs have been made in natural gas exploration of Middle Permian Maokou formation in Northwest Sichuan basin showing further exploration and development potential of natural gas reservior in the area.Exploration is depending and aboundant data accumulated.The problem of source of gas in the area is urgently to be solved.Combined with genetic discrimination diagram,hydrocarbon source rock of different rock sequence and gas characteristics gas-source and gas-gas comparative analysis are carried out on basis of analysis of gas samples and experimental data then genetic types and major source rocks of natural gas of Maokou formation in each gas fields in the Northwest Sichuan basin classified.The conclusion is that(1)CH 4 of natural gas from Maokou formation in Yuanba,Jiulongshan,Shuangyushi,Hewanchang,Wujiaba and Kuangshanliang gas fields is the highest constituent(averagely 93.64%),heavy hydrocarbon C_(2+)low,the gas belongs to highly evoluted dry gas with drying coeficient>0.99,multi-types of non-hydrocarbon cases occur and their contents varied in each gas field,value of 13 for each gas field is quite different;(2)natural gas of Yuanba,Jiulongshan,Shuangyushi and Kuangshanliang gas fields belongs to highly matured and overmatured mixture of oil gas and coal gas,that of Hewanchang gas field highly matured oil gas,natural gas of Maokou formation in the Northwest Sichuan basin occur at the intersection of cracking gas of cute oil and cracking gas of kerogen and proportion of two cracking gas is different for each gas field;(3)natural gas of Maokou formation in Northwest Sichuan basin is derived from multi-sources.Hydrocarbon of the gas from Yuanba and Jiulongshan gas fields is supplied by both source rocks of Wujiaping formation and Maokou formation,that of Shuangyushi gas field by source rocks of Maokou formation and Qiongzhusi formation,that of Hewanchang gas field by source rocks at lower Qiongzhusi formation,that of Kuangshanliang gas field by source rocks of Maokou formation,that of Wuji

关 键 词：天然气地球化学 天然气成因类型 气源对比 茅口组 川西北地区 

分 类 号：P618.13[天文地球—矿床学] P595[天文地球—地质学]