塔里木盆地顺北地区白垩系原油成因类型与来源

Genetic types and sources of Cretaceous crude oil in Shunbei area, Tarim Basin

吴鲜 曹自成 路清华 洪才均

WU Xian CAO Zicheng LU Qinghua HONG Caijun

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

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

塔里木盆地白垩系含油层系具有良好的勘探潜力，顺北地区在白垩系有较好的油气显示，测试获得少量原油。为研究顺北地区白垩系原油地球化学特征、成因类型、油气来源，系统开展了地球化学特征分析、油—油、油—源对比研究。顺北地区白垩系原油饱和烃色谱为单峰前峰型，正构烷烃系列保存完整，谱图基线平稳，未见明显的“鼓包”，原油Pr/Ph分布在1.65~1.71，C21TT/C23TT>1，生标图谱中藿烷系列化合物占明显优势，∑三环萜烷/∑藿烷 < 1，检测到丰度较高的伽马蜡烷和三芳甾烷化合物，指示为保存条件良好的陆相成因类型原油；顺北白垩系原油与北部库车坳陷周缘的英买、大宛齐、大涝坝白垩系原油、库车河三叠系黄山街组泥质烃源岩具有较好的亲源性，指示油源来自库车坳陷三叠系黄山街组泥质烃源岩；白垩系原油热演化程度从大宛齐到英买再到顺北呈现出降低的趋势，推测顺北白垩系原油可能来源于库车坳陷三叠系烃源岩，生成的早期陆相油气沿白垩系优质砂体、T40不整合面、断裂由北向南远距离侧向运移。

The Cretaceous oil-bearing strata in the Tarim Basin have a good exploration potential. The Shunbei area has good oil and gas shows in the Cretaceous, and a small amount of crude oil has been obtained by testing. The geochemical characteristics of the Cretaceous crude oil as well as the oil-oil and oil-source correlations were studied systematically in order to determine the genesis types and sources of crude oil in the Shunbei area. The saturated hydrocarbon chromatogram of the Cretaceous crude oil in the Shunbei area shows a unimodal distribution. The n-alkanes are intact and the distribution is unchanged without any obvious "UCM". The Pr/Ph values of crude oil range 1.65-1.71. The C21TT/C23TT ratio is >1. In biomarkers, the hopane series are dominant and the ∑tricyclic terpanes/∑hopanes ratio is < 1. The gammacerane and triaryl stanine compounds are abundant, indicating that the crude oil of continental origin is well preserved. The Cretaceous crude oil in the Shunbei area and the Yingmai, Dawanqi and Dalaoba areas around the Kuqa Sag in the north, and the Triassic Huangshanjie mudstones in the Kuqa River area show similar m/z 191 biomarker patterns, which indicates that the crude oil was sourced from the Huangshanjie mudstones in the Kuqa Sag. The thermal evolution degrees of crude oil decrease from Dawanqi, Yingmai to Shunbei. We inferred that the early terrestrial hydrocarbon was sourced in the Triassic source rocks in the Kuqa Sag, and then migrated laterally from north to south through the Cretaceous sand bodies, the T40 unconformity surface and the faults.

“十三五”国家科技重大专项 2017ZX05005-002-001

https://doi.org/10.11781/sysydz202002255