摘要
东道海子凹陷是准噶尔盆地二叠系重要的勘探领域之一,二叠系平地泉组是该区烃源岩发育的重点层系。通过对东道海子凹陷烃源岩分布及有机质地球化学特征分析,明确了平地泉组烃源岩生烃潜力及生成油气的类型。研究结果表明:①东道海子凹陷平地泉组烃源岩的Pr/nC17值为0.35~1.18,Ph/nC18值为0.23~0.81,显示其生烃母质主要为混合源,既有陆地生物的贡献,也有水体生物的贡献。②纵向上,平一段和平二段烃源岩质量最好,平一段的好—优质烃源岩占比为81.1%,TOC平均值为1.88%,平二段的好—优质烃源岩占比为62.5%,TOC平均值为1.55%,而平三段的好—优质烃源岩仅占30.2%。平一段和平二段烃源岩主要为Ⅱ型,占比分别为66.7%和48.4%,既可生油也可生气,平三段烃源岩质量较差,以Ⅲ型干酪根为主,具有一定的生气潜力;平面上,烃源岩从边缘区向凹陷区逐渐变好。③凹陷边缘区的烃源岩达到成熟演化阶段,凹陷区烃源岩埋深较大,达到高—过成熟演化阶段,该套烃源岩在埋深约为2500m时达到生烃门限,在埋深为4350m处达到大量排烃门限,而当埋深大于5050m时,进入大量裂解生气阶段。④研究区油气分布明显受烃源岩分布及成熟度控制,在远源端剥蚀区浅层侏罗系八道湾组发现成熟油,下凹斜坡区二叠系以轻质油为主,而凹陷中心以平地泉组“自生自储”气藏为主。
Dongdaohaizi sag is one of the important exploration fields for Permian in Junggar Basin,and the Per-mian Pingdiquan Formation is the key formation for the development of source rocks in this area.Based on the analysis of source rock distribution and geochemical characteristics of organic matters,the hydrocarbon genera‐tion potential and types of the source rocks of Pingdiquan Formation in Dongdaohaizi sag were determined.The results show that:(1)The Pr/nC17 and Ph/nC18of Pingdiquan Formation source rocks in Dongdaohaizi sag are 0.35-1.18 and 0.23-0.81,respectively,indicating that the source rocks are mainly sourced from mixed facies,with contributions from both terrestrial and aquatic organisms.(2)Vertically,Ping-1 member and Ping-2 member have the best source rock types.The proportion of good-quality source rocks of Ping-1 member and Ping-2 member is 81.1%and 62.5%,respectively,and the average TOC is 1.88%and 1.55%,respectively.The proportion of good-quality source rocks in Ping-3 member is only 30.2%.The source rocks of Ping-1 member and Ping-2 member are mainly typeⅡ,accounting for 66.7%and 48.4%respectively,which can generate both oil and gas.The source rocks of Ping-3 member are of poor quality,dominated by typeⅢkerogen,and have certain gas potential.On the plane,from marginal area to sag area,the source rocks gradually become better.(3)The source rocks in the marginal area have reached mature evolution stage,and the source rocks in the sag have large burial depth,reaching high and over-mature evolution stage.Source rocks of Pingdiquan Formation reach hydrocarbon genera‐tion threshold at about 2500 m,and massive hydrocarbon expulsion threshold at 4350 m.When the depth reaches 5050 m,it is in the stage of massive pyrolysis and gas generation.(4)The distribution of oil and gas in the study area is obviously controlled by the distribution and maturity of source rocks.Therefore,mature oil is mainly found in the shallow Jurassic Badaowan Formation in the far-source denudation area,and light oil is found in Permian in sag slope area.However,the exploration in deep sag should take self-generating and self preserving gas reser‐voirs of Pingdiquan Formation as target.
作者
李二庭
米巨磊
张宇
潘越扬
迪丽达尔·肉孜
王海静
高秀伟
LI Erting;MI Julei;ZHANG Yu;PAN Yueyang;DILIDAER Rouzi;WANG Haijing;GAO Xiuwei(Xinjiang Laboratory of Petroleum Reserve in Conglomerate,Karamay 834000,Xinjiang,China;Research Institute of Experiment and Detection,PetroChina Xinjiang Oilfield Company,Karamay 834000,Xinjiang,China)
出处
《岩性油气藏》
CAS
CSCD
北大核心
2024年第1期88-97,共10页
Lithologic Reservoirs
基金
中国石油重大工程技术现场试验项目“准噶尔南缘和玛湖等重点地区优快钻完井技术集成与试验”(编号:2019F-33)资助。
关键词
烃源岩
生烃潜力
地球化学特征
自生自储
平地泉组
二叠系
东道海子凹陷
准噶尔盆地
source rock
hydrocarbon generation potential
geochemical characteristics
self-generating and self preserving
Pingdiquan Formation
Permian
Dongdaohaizi sag
Junggar Basin
