渤中凹陷西次洼陡坡带精细油源对比

Oil-source rock correlation of steep slope of western subsag of Bozhong Sag

齐玉民 郝鹏 王渝 佟朝晖 李志勇 王岩岩

中海油能源发展工程技术分公司中海油实验中心，天津 300452

CNOOC Experiment Center, CNOOC EnerTech-Drilling & Production Co., Tianjin 300452, China

文中系统分析和总结了渤中凹陷西次洼沙河街组（沙一段、沙三段）和东营组（东三段、东二下亚段）烃源岩的有机地球化学特征，明确了主力烃源岩和各套烃源岩在沉积环境和母源输入方面的差异性。在此基础上，应用饱和烃生物标志化合物、碳同位素等地球化学分析资料，多种方法相结合，对渤中凹陷西次洼陷陡坡带原油进行了详细地油油和油源对比。研究结果表明，沙河街组生烃潜力高于东营组，东三段陆源有机质输入高，沙一段形成于强还原环境，富含伽马蜡烷，沙三段低等水生生物十分发育。依据C24/C26（S+R）、C29 S/（R+S）、4MSI及γ蜡烷指数等生物标志化合物参数可以区分各套烃源岩。研究区原油东营组烃源岩的贡献不明显，主要具有3种成因类型，分别为来源于沙三段、沙一段烃源岩的“沙三型原油”、“沙一型原油”和来源于2套烃源岩的“混合型原油”。其中，“混合型原油”为主要类型，在东、西部古近系和新近系储层均有分布，“沙三型原油”和“沙一型原油”分布于陡坡带东部的古近系储层。陡坡带西部深、浅层原油生物标志物特征一致，由同一套沙河街组烃源岩供烃，陡坡带东部原油垂向上差异性大，具有多源多次充注的成藏特征。

This paper systematically analyses and summarizes the geochemical characteristics of source rocks of Shahejie (E2s3, E2s1) and Dongying(E3d3, E3d2L) Formations in the western subsag, Bozhong Sag. The main source rocks and the different depositional environments and organic matter input characteristics of each set of source rocks were identified. On this basis, applying saturated-hydrocarbon biomarker, carbon isotope and other data, with a combination of these approaches, a detailed research on oil-oil correlation and oil-source correlation of steep slope of the western subsag in Bozhong Sag was given. The results show that source rocks of the Shahejie Formation have higher hydrocarbon generation potential; the source rocks from the Member E2d3 are characterized by high amount of terrestrial plants; the source rocks from the Member E2s1 are marked with strong reducing sedimentary environment and have high gammacerane index; the source rocks from the Member E2s3 are dominated by lower rearranged steranes. Applying the biomarker methods of C24/C26 (S+R), C29S/(R+S), gammacerane index and 4MSI, the source rocks can be identified. Oil samples present no correlation with the Dongying Formation source rocks, and there are three genetic types, E2s3 crude oil from E2s3 source rock, E2s1 crude oil from E2s1 source rock and mixed oils from two serial Shahejie source rocks. Mixed oil is the main type in the eastern and western Palaeogene-Neogene reservoirs, E2s3 and E2s1 crude oil distribute in Paleogene reservoirs in the eastern area. The biomarkers from deep and shallow crude oil in the western of the steep slope were supplied by the same hydrocarbon source rocks of Shahe Formation. The crude oil in the eastern part of the steep slope varies vertically, and is characterized by multi-sources and multi-stage accumulations.

10.6056/dkyqt201802004