复合油藏形成中的蒸发分馏与生物降解联合控制作用——以渤海海域秦皇岛29-2油田为例  

Evaporative fractionation and biodegradation impacts on a complex petroleum system:QHD29-2 oil field,Bohai Sea area

作　　者：牛成民 王飞龙 汤国民 燕歌 赵国祥 NIU Chengmin;WANG Feilong;TANG Guomin;YAN Ge;ZHAO Guoxiang(Research Institute of Bohai Oilfield, Tianjin Branch of CNOOC Ltd, Tianjin 300452, Chin)

机构地区：[1]中海石油(中国)有限公司天津分公司渤海石油研究院,天津300452

出　　处：《石油实验地质》2018年第3期381-388,共8页Petroleum Geology & Experiment

基　　金：国家科技重大专项(2016ZX05024-002-006);国家自然科学基金项目(41602111)联合资助

摘　　要：通过对秦皇岛29-2油田地质构造背景、油气及其烃源岩地化特征等方面研究,从蒸发分馏与生物降解共控的角度探讨了秦皇岛29-2油气藏原油物性差异性成因。研究结果表明:油源对比证实该古近系油藏与新近系油藏同源,但它们在轻烃组成、族组成和饱和烃色谱分布上存在显著差异,表明经历了强烈的蒸发分馏作用。结合该区烃源岩热演化、成藏期次和断裂活动史认为,幔源CO_2气体侵入引起了该区蒸发分馏作用;蒸发分馏和生物降解作用联合控制着该油气藏的原油物性差异分布,深、浅层油藏整体受控于前者,浅层油藏同时受控于后者,从深到浅依次分布着特稠油、轻质油、凝析油和稠油;2种作用共存于同一油藏,既需要有已遭受蒸发分馏影响的先存深层油藏,也需要后成藏的浅层油藏遭到生物降解的同时,接受先存油藏的晚期持续充注。By studying the tectonic background of QHD29- oil field and the geochemical characteristics of oiland gas and its source rocks, the dissimilarity of crude oil physical properties was discussed from the perspectiveof evaporative fractionation and biodegradation. Oil source comparison confirmed that the oils in Paleogene andNeogene had the same source. However, there were significant differences in light hydrocarbon composition,family composition and the chromatographic distribution of saturated hydrocarbons, indicating that they had expe-rienced a strong evaporative fractionation. Combined with the analyses of source rock thermal evolution, accumu-lation stage and fault activity history, it was believed that the intrusion of mantle-derived CO2 gas had causedevaporative fractionation in the area. The evaporative fractionation and biodegradation jointly controlled crude oilphysical properties in the reservoir. Evaporative fractionation and biodegradation were the main factors controllingthe differences of crude oil physical properties in reservoirs, and the differences were mainly controlled by evapo-rative fractionation, whereas, the oil in shallow reservoirs was controlled by both evaporation and biodegradation.Extra-heavy, light, condensate and heavy oils distributed in sequence from deep to shallow reservoirs. The twomechanisms had an impact on the same reservoir simultaneously. The early reservoirs in deep formations wereaffected by evaporative fractionation. After the shallow reservoirs of the post-accumulation were biodegraded, theywere continuously charged in the late stage of the pre-existing reservoir.

关 键 词：蒸发分馏 生物降解 秦皇岛29-2油田 复合油藏 秦南凹陷 渤海海域 

分 类 号：TE122.11[石油与天然气工程—油气勘探]