准噶尔盆地东道海子凹陷及周缘上古生界原油成因来源OA北大核心CSTPCD
Genetic Types and Origins of Upper Paleozoic-reservoiered Oil in Dongdaohaizi Sag and Its Surrounding Areas in the Junggar Basin
东道海子凹陷的钻探工作始于20世纪90年代,但由于复杂的构造演化和沉积特征,该区勘探长期停滞不前.直到近期,部署在东道海子凹陷的探井中屡屡发现良好油气显示,使该区的油气勘探重燃希望.目前,对该区油气成因来源的认识还很薄弱,给勘探方向的选择造成了较大的困难.文章对东道海子凹陷及周缘石炭系和二叠系储层中原油的稳定碳同位素组成、类异戊二烯烷烃和甾萜类生物标志化合物等地球化学特征进行了系统分析,划分了原油的成因类型,再结合研究区主力烃源岩的地球化学特征,最终厘清了各类原油的来源.结果表明,研究区原油总体已进入主生油窗,属于成熟原油,分为三种不同类型.第一类原油稳定碳同位素组成重,Pr/Ph值较高,含有丰富的C19三环萜烷、C20三环萜烷和C24四环萜烷,伽马蜡烷指数低,来自下石炭统松喀尔苏组b段的淡水腐殖型烃源岩.第二类原油稳定碳同位素组成轻,Pr/Ph值相对较低,含有丰富的β-胡萝卜烷和伽马蜡烷,但C19三环萜烷、C20三环萜烷和C24四环萜烷的丰度较低,来自中二叠统平地泉组咸水湖相烃源岩.第三类原油的地化特征介于上述两类原油之间,表现出混源特征.上述认识提供了一个在多源叠置区开展油源对比的典型案例,同时也为东道海子凹陷及周缘下一步油气勘探指明了方向.
Drilling in Dongdaohaizi sag started in the 1990s,but little progress has been made in oil and gas exploartaion due to the complex structural evolution and sedimentary characteristics for a long time.Recently,oil and gas indications have been found repeatedly in the exploratory wells deployed in the Dongdaohaizi Sag,which has rekindled the hope of oil and gas exploration in this area.However,the understanding of the origin of oil and gas in this area is still poor,causing significant difficulties in selecting an exploration direction.Based on systematical analyses of stable carbon isotope composition,isoprenoid alkane,sterane terpane biomarkers,and other geochemical characteristics of crude oil and source rocks in the Carboniferous and Permian strata of Dongdaohaizi sag and its surrounding areas,the genetic types and oil sources were discussed.The results showed that the crude oil in the study area has entered the main oil generation window,which belongs to mature crude oil and can be divided into three different types.Type I oil is characterized by heavy stable carbon isotope composition,high Pr/Ph ratio,abundant C19 tricyclic terpanes,C20 tricyclic terpanes and C24 tetracyclic terpanes,and low gammacerane index.These features indicate that it was derived from humic source rocks in the Lower Carboniferous Songkarsu formation,which was deposited in a freshwater environment.Type II oil is characterized by relatively light stable carbon isotope composition,relatively low Pr/Ph ratio,abundant β-Carotene,high gammacerane index,and low abundance of C19 tricyclic terpane,C20 tricyclic terpane,and C24 tetracyclic terpane.These features indicate that it was derived from the saline lacustrine source rocks in the middle Permian Pingdiquan formation.Geochemical characteristics of Type III oil are between those of Types I and II crude oil,showing a mixed source.The above findings provided a type case of oil source correlation in a multi-source superimposed area and also pointed out the direction for future petroleum exploration in the Dongdaohaizi sag and its surrounding areas.
尹晟宇;龚德瑜;苏静;胡正舟;吴卫安;王瑞菊
中国地质大学(北京)能源学院,北京 100083||中国石油勘探开发研究院,北京 100083中国石油勘探开发研究院,北京 100083中国石油新疆油田公司 勘探开发研究院,克拉玛依 8340003
地质学
准噶尔盆地东道海子凹陷油源对比石炭系二叠系稳定碳同位素组成生物标志化合物
Junggar BasinDongdaohaizi sagoil source correlationCarboniferousPermianstable carbon isotope compositionbiomarker fingerprints
《高校地质学报》 2024 (002)
218-230 / 13
自然科学基金项目(41802177;42272188);中国石油前瞻性基础性战略性技术攻关项目(2021DJ0206;2022DJ0507);中国石油直属院所基础科学研究和战略储备技术研究基金(2020D-5008-04)联合资助
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