四川盆地开江—梁平海槽周缘长兴组—飞仙关组气源差异及龙潭组煤成气有利勘探方向  

Differences in gas sources of the Changxing-Feixianguan formations around the Kaijiang-Liangping trough and favorable exploration directions for coal-formed gas generated by the Upper Permian Longtan Formation, Sichuan Basin

作　　者：黄士鹏[1] 赵振宇[1] 艾悦 姜华[1] 田兴旺[2] 江青春[1] 马德波[1] 宋微[1] 宋海敬[1] Shipeng HUANG;Zhenyu ZHAO;Yue AI;Hua JIANG;Xingwang TIAN;Qingchun JIANG;Debo MA;Wei SONG;Haijing SONG(Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;PetroChina Southwest Oil and Gasfield Company,Chengdu 610041,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油西南油气田分公司,四川成都610041

出　　处：《天然气地球科学》2024年第5期799-809,共11页Natural Gas Geoscience

基　　金：中国石油油气和新能源公司科技专项“中国石油重点地区风险勘探目标研究”(编号:2023YQX10101);国家自然科学基金“油气成藏次生作用过程中轻烃组分与同位素分馏机理”(编号:42372165)联合资助。

摘　　要：基于天然气组分、碳氢同位素、储层沥青、烃源岩条件和源储组合分析,明确了四川盆地开江—梁平海槽两侧长兴组—飞仙关组天然气的来源及其差异,并指出了龙潭组煤成气的有利勘探方向,取得如下认识:(1)长兴组—飞仙关组天然气主体上以烷烃气为主,均为典型干气;(2)海槽东侧长兴组—飞仙关组甲、乙烷碳同位素组成明显轻于海槽西侧,西侧的龙岗气田乙烷碳同位素组成要重于元坝气田,而甲烷氢同位素组成则要比元坝气田偏轻;(3)东岳寨气田、普光气田和元坝气田天然气主要来源于吴家坪组II_(1)—I型腐泥型有机质;龙岗气田则是煤成气和油型气的混合气,煤成气的比例稍高,来源于吴家坪组II_(1)—II_(2)型混合型有机质;(4)龙潭组内部可形成煤岩气、致密砂岩气和页岩气等多类型气藏。遂宁—泸州、阆中—广安—涪陵一带分别是煤岩气和海—陆过渡相页岩气勘探的有利区带;遂宁—合川、广安—南充一带长兴组礁滩发育区也是煤成气勘探的有利勘探区带。Through the analysis of natural gas composition,carbon and hydrogen isotopes of alkane gases,reservoir bitumen,source rock conditions,and source-reservoir combination,the gas source differences and sources of natural gas in the Permian Changxing Formation-Triassic Feixianguan Formation on both sides of the Kaijiang-Liangping trough were clarified,and favorable exploration directions for the coal-formed gas generated by the Longtan Formation were pointed out in the Sichuan Basin.The following understanding was obtained:(1)The natural gas in the Changxing-Feixianguan formations is mainly composed of alkane gas,which is typical dry gas;(2)The carbon isotope values of methane and ethane in the Changxing-Feixianguan formations on the east side of the trough are lighter than those on the west side.The ethane carbon isotope in the Longgang Gas Field on the west side is heavier than that in the Yuanba Gas Field,while the value of methane hydrogen isotope is lower than that in the Yuanba Gas Field;(3)The natural gas from Luojiazhai,Puguang,and Yuanba gas fields mainly comes from the sapropelic organic matter of the Wujiaping Formation with kerogen type II_(1)-I;the Longgang Gas Field is a mixture of coal-formed gas and oil type gas,with a slightly higher content of coal-formed one,originating from the mixed organic matter of the Wujiaping Formation with kerogen type of II_(1)-II_(2);(4)Multiple types of gas,such as coal rock gas,tight sandstone gas,and shale gas,can be formed within the Longtan Formation.The Suining-Luzhou and Langzhong-Guang'an-Fuling areas are favorable zones for the exploration of coal rock gas and marine-continental transitional shale gas,respectively.The reef and shoal development areas of the Changxing Formation in the Suining-Hechuan and Guang'an-Nanchong areas are also favorable exploration areas for coal-formed gas.

关 键 词：长兴组—飞仙关组 天然气成因 来源 吴家坪组 龙潭组 煤成气 有利勘探方向 

分 类 号：TE122.1[石油与天然气工程—油气勘探]