塔里木盆地巴楚隆起盐下白云岩中油气来源

Source of hydrocarbons discovered from Cambrian sub-salt dolomite in Bachu uplift area, Tarim Basin

曹自成 朱秀香 吴鲜 徐勤琪 路清华 李建交 蒋海军

CAO Zicheng ZHU Xiuxiang WU Xian XU Qinqi LU Qinghua LI Jianjiao JIANG Haijun

中国石化 西北油田分公司, 乌鲁木齐 830011 中国石化 西北油田分公司 勘探开发研究院, 乌鲁木齐 830011 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126 中国石化 石油勘探开发研究院, 北京 100083

Northwest Oilfield Company, SINOPEC, Urumqi, Xinjiang 830011, China Exploration and Production Research Institute of Northwest Oilfield Company, SINOPEC, Urumqi, Xinjiang 830011, China Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China SINOPEC Petroleum Exploration and Production Research Institute, Beijing 102206, China

勘探研究表明，塔里木盆地巴楚隆起不发育下寒武统主力烃源岩，但该区MB1井在下寒武统见较好油气显示。为了明确MB1井的油源、评价巴楚隆起的勘探潜力，对MB1井下寒武统吾松格尔组油气显示段岩心抽提物进行了地球化学分析，进一步开展了油—油、油—源对比等研究，揭示了油气物质的成因特征与来源。结果表明，抽提物具有典型的塔里木盆地海相原油的地球化学特征，即饱和烃色谱图为单峰前峰型，正构烷烃系列保存完整，谱图基线平整、未见明显的“鼓包”，Pr/Ph比值为0.89，三环萜烷系列的相对丰度高于藿烷系列，C27-C28-C29ααα20R规则甾烷具有明显的“V”字型分布特征，原油碳同位素值为-30.8‰，三芴系列化合物表现为明显的硫芴优势，指示其来源于强还原沉积环境的腐泥型生烃母质，处于高成熟演化阶段。MB1井下寒武统油显示与玉北1条带奥陶系原油同源，均来自于下寒武统烃源岩，推测巴楚隆起MB1井下寒武统油气来自周边下寒武统烃源岩或古油藏，从而提升了该区寒武系的勘探潜力。

Exploration experiences have showed that the main source rocks of the Lower Cambrian have not been developed in the Bachu uplift; however, the well MB1 in this area had a good oil and gas showing in the Lower Cambrian.To clarify the hydrocarbon source of well MB1 and evaluate the exploration potential of the Bachu uplift, the core extracts from the oil and gas display section of the Lower Cambrian Wusongge'er Formation of well MB1 were studied here by using of geochemical analysis, moreover, oil-oil and oil-source correlations have also been carried out.The saturated hydrocarbon fraction of extracts showed a typical signature which is consistent with marine crude oil in the Tarim Basin, of which the n-alkanes have a single-peak pre-peak distribution, the series is preserved intact and there was no apparent "hump" in the basline, the ratio of Pr/Ph was 0.89, the abundance of the tricyclic terpanes was higher than that of the hopanes, the C27-C28-C29ααα20R regular steranes had a typical "V" shape, the carbon isotope value of crude oil is -30.8‰, and the trifluorene compounds were obviously override thiofluorene.It then indicates that they were derived from the saprolite-type sources with a strongly reducing sedimentary environment, moreover, the organic matters are high mature.The Lower Cambrian oil showed in well MB1 have the same origin as the Ordovician crude oil in the Yubei 1 belt, and both of them probably came from the Lower Cambrian source rocks. It was inferred that the Lower Cambrian oil and gas in well MB1 came from the peripheral Lower Cambrian source rocks or paleo-oil reservoirs, which enhanced the exploration potential of Cambrian in the Bachu uplift.

国家自然科学基金项目“海相深层油气富集机理与关键工程技术基础研究” U19B6003-02

https://doi.org/10.11781/sysydz202104648