摘要
通过对川北地区上二叠统大隆组3条野外剖面进行系统采样和地球化学特征分析,从沉积背景、热液活动与上升流、古气候和古盐度、水体环境等4个方面分析了烃源岩的沉积环境,并对有机质富集模式和勘探潜力进行了探讨。研究结果表明:(1)川北地区二叠系大隆组烃源岩岩性主要为泥质、硅质泥灰岩,有效厚度为10~40 m,有机质丰度高、类型好,TOC平均值为4.58%,以Ⅱ2型为主,生烃潜力大,平均热解生烃潜量为5.90 mg/g。盆地边缘广元地区长江沟剖面和西北乡剖面处于成熟阶段,Ro值分别为0.72%和1.06%,盆地东部大两乡剖面平均T_(max)值为604℃,达过成熟阶段,广元—梁平海槽大隆组生气量达432.38×10^(12)m^(3),常规天然气资源量为1.70×10^(12)m^(3),页岩气资源量达万亿方级,是一套生气潜力较大的海相优质烃源岩。(2)研究区大隆组优质烃源岩形成于水体缺氧半局限循环的大陆边缘环境,经历了海槽发育雏形期和海槽发育扩展期2期水体环境的演变,其中,雏形期呈现缺氧—局部厌氧—缺氧的非硫化夹硫化环境,有机质不发育;扩展期为贫氧—缺氧—主体厌氧—缺氧环境,热液活动与上升流导致生物繁盛,火山喷发的酸性气体与半封闭水体环境共同造就了长时期大范围的厌氧硫化静海环境,有利于有机质的富集与保存,在西北乡和长江沟等斜坡—陆棚区表现出较高的TOC值,弱滞留硫化环境中TOC值最大,中等滞留硫化环境次之,强滞留硫化环境中TOC值最小。(3)研究区大隆组页岩气和源于大隆组热解气的长兴组—飞仙关组优质气藏为主要勘探方向。
Through systematic sampling and geochemical characteristics analysis of three field profiles of Upper Permian Dalong Formation in northern Sichuan Basin,the sedimentary environment of source rocks was analyzed from four aspects of sedimentary background,hydrothermal activity and upwelling,paleoclimate and paleosalinity,and water environment,and the organic matter accumulation model and exploration potential were discussed.The results show that:(1)The Permian Dalong Formation in northern Sichuan Basin has argillaceous and siliceous source rocks with an effective thickness of 10-40 m,a high abundance of organic matters(the average content of organic carbon is 4.58%),good types of organic matters(type Ⅱ2 organic matter is dominant),and great hydrocarbon generation potential(the average pyrolysis hydrocarbon generation potential is 5.90 mg/g).The Changjianggou profile and Xibeixiang profile in Guangyuan area at the margin of Sichuan Basin are in mature stage,with Ro values of 0.72% and 1.06%,respectively.The average T_(max) value of Daliangxiang profile in the eastern part of the basin is 604 ℃,reaching an over mature stage.The gas generation of Dalong Formation in Guangyuan-Liangping trough reaches 432.38×10^(12)m^(3),with conventional natural gas resource of 1.70×10^(12)m^(3) and shale gas resource in trillions of cubic meters,which is a set of marine high-quality source rocks with large gas potential.(2)The high-quality source rocks of Dalong Formation in the study area were formed in a continental margin environment with semi-limited cycle of water hypoxia,and experienced two stages of the evolution of water environment,including embryonic stage and expansion stage of the trough development.In the early stage,there was anoxic-local anaerobic-anoxic unvulcanized and sulphide environment,and organic matter was not developed.In the middle and late stages,there was an oxygen-poor-anoxic-main anaerobic-anoxic environment.Organic matter enrichment was closely related to hydrothermal activity and upwelling.The aci
作者
郭谨豪
胡国艺
何坤
米敬奎
田连杰
贺飞
郭楚媛
卢梦蝶
GUO Jinhao;HU Guoyi;HE Kun;MI Jingkui;TIAN Lianjie;HE Fei;GUO Chuyuan;LU Mengdie(PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China;Key Laboratory of Petroleum Geochemistry,CNPC,Beijing 100083,China;China University of Mining and Technology(Beijing),Beijing 100083,China)
出处
《岩性油气藏》
CAS
CSCD
北大核心
2023年第5期139-152,共14页
Lithologic Reservoirs
基金
国家自然科学基金“深层无机流体-有机质作用生气机制及同位素分馏效应”(编号:41973068)
中国石油科技项目“高—过成熟烃源岩生排气机理与大气田(区)气源灶潜力评价研究”(编号:2021DJ0601)联合资助。
关键词
地球化学特征
生烃潜力
缺氧半局限环境
热液活动
有机质富集模式
大隆组
上二叠统
广元—梁平海槽
川北地区
geochemical characteristics
hydrocarbon generation potential
hypoxic semi-limited environment
hydrothermal activity
organic matter enrichment model
Dalong Formation
Upper Permian
Guangyuan-Liangping trough
northern Sichuan Basin
