摘要
柴达木盆地西部凹陷区是重要的油气勘探领域,发育独特的古近系-新近系高原咸化湖相烃源岩。近年来,天然气勘探在南翼山、黄瓜峁、开特米里克、英中和扎哈泉等中深层获得了重要发现,发现多个天然气藏。但是该区的天然气来源存在较大争议,是否存在深层侏罗系煤型气的混入影响着对该地区天然气、成藏模式的认识以及下一步的勘探方向。在综合分析大量天然气样品地球化学特征的基础上,研究柴西地区古近系-新近系与柴北缘侏罗系天然气地球化学特征差异性,以及伴生原油地球化学特征和区域地质条件,取得以下3点认识:(1)与其他地区不同,乙烷碳同位素不能作为鉴别柴西地区高成熟咸化湖相天然气类型的主要指标;(2)柴西地区天然气主要来源于自身发育的下干柴沟组上段(E32)和上干柴沟组(N1)咸化湖相烃源岩,主要为油型气,几乎不存在侏罗系煤型气的混入;(3)柴西地区天然气成藏具有就近成藏的特点,横向短距离运移,垂向晚期调整。并指出烃源岩埋深大、成熟度高的区域,如英东、黄瓜峁-开特米里克和南翼山-油墩子地区,是今后重要的勘探领域。
The western depressed area of the Qaidam Basin is an important zone for oil and gas exploration,with unique Paleogene-Neogene source rocks in plateau saline lake facies.In recent years,important discoveries have been made in the middle-deep layers of Nanyishan,Huangguayao,Kaitemilike,Yingzhong and Zahaquan,etc.,and many natural gas reservoirs have been discovered.However,the source of natural gas in this area is controversial.Whether there is mixed deep Jurassic coal-type gas affects the understanding of natural gas and reservoir-forming model in this area and the next exploration direction.On the basis of comprehensive analysis of geochemical characteristics of a large number of natural gas samples,the geochemical differences of natural gas between Paleogene-Neogene in western Qaidam Basin and Jurassic in the northern margin of the Qaidam Basin,and the geochemical characteristics of associated crude oil and regional geological conditions were studied,and the following three cognitions were obtained:(1)Unlike other regions,carbon isotope of ethane cannot be used as the main index to identify the type of high mature saline lacustrine natural gas in western Qaidam Basin.(2)The natural gas in western Qaidam Basin mainly comes from the saline lacustrine source rocks of the upper member of the Lower Ganchaigou Formation(E3 2)and the Upper Ganchaigou Formation(N1).They are mainly oil-type gas,and there is almost no mixed Jurassic coal-type gas.(3)Gas accumulation in western Qaidam Basin is characterized by near source,with short transverse migration distance and late vertical adjustment.The areas with deep burial and high maturity of source rocks,such as Yingdong,Huangguayao-Kaitemilike and Youdunzi,are important exploration areas in the future.
作者
张永庶
周飞
王波
曾旭
张静
张小波
Zhang Yongshu;Zhou Fei;Wang Bo;Zeng Xu;Zhang Jing;Zhang Xiaobo(Research Institute of Exploration and Development,PetroChina Qinghai Oilfield Company;PetroChina Research Institute of Petroleum Exploration&Development)
出处
《中国石油勘探》
CAS
CSCD
北大核心
2019年第4期498-508,共11页
China Petroleum Exploration
基金
国家科技重大专项“柴达木复杂构造区油气成藏、关键勘探技术与新领域目标优选”(2016ZX05003-006)
中国石油天然气股份有限公司重大科技专项“柴达木盆地建设高原大油气田勘探开发关键技术研究与应用”(2016E-0102)
关键词
油型气
煤型气
天然气碳同位素
天然气类型
柴西地区
oil-type gas
coal-type gas
carbon isotope of natural gas
natural gas type
western Qaidam Basin
