柴西地区原油有机地球化学特征及意义

Organic Geochemical Characteristics and Significance of Crude Oil in Western Qaidam Basin

通过现有原油物性资料与利用有机地球化学分析技术所得到的正构烷烃、类异戊二烯烷烃、霍烷、甾烷及芳烃分析数据相结合,综合研究柴西地区昆北断阶带、扎哈泉、英东、南翼山及小梁山油田原油性质和地球化学特征,明确了该区的母质类型来源于陆源物质与水生生物都有贡献的混源,其沉积环境属于咸化还原环境,柴西原油未经过强烈的环化-芳构化、热作用、脱羧基和脱羰基等作用,具有低成熟-成熟原油的演化特征,成烃环境细菌微生物发育提高了烃源岩在较低演化阶段的生烃能力,为该区进一步油气勘探部署、储量研究、开发方案编制等起到了很好的技术支撑作用。

In recent years, the step-fauh zone in the north of Kunlun Mountains, the Zaha Springs and the Yingdong areas are the major breakthrough in the areas of oil and gas exploration in Qaidam Basin. With the analysis techniques and tools of oil/gas fluid physical properties and organic geochemistry on normal paraffin, isoprenoid alkanes, hopane, sterane and aromatic hydrocarbon, this paper made a comprehensive study of crude oil properties and geochemical characteristics of the step- fault zone in the north of Kunlun Mountains, the Zaha Springs, the Yingdong areas, Nanyi Mountains and Xiaoliang Mountains in western Qaidam Basin. It has been explicated that the parent material was derived from terrigenous materials and aquatic organisms; its depositional environment belongs to salinization-reductive environment ; its crude oil has the evolution characteristics of the low mature-mature crude oil without strong ring formation-aromatization, thermal effect, decarboxylation and decarbonylation and so on. The bacteria microbial growth of hydrocarbon generation environment improves the generation ability of generating rocks in the lower evolutionary stages. This research findings provide a good technology support for the next oil/gas exploration deployment, reserves research, development plan compilation and so on.