【摘要】 塔里木盆地阿瓦提凹陷—满加尔凹陷过渡区域(简称阿—满过渡带)多年来一直未发现奥陶系烃源岩,但大量的地球化学资料分析结果却将塔中与塔北地区的油气源区指向了该地区。针对这一现象,对该区构造高部位多口钻井中的中—上奥陶统泥岩样品进行了有机碳含量复查与分析,初步在塔中29井识别出一套海相烃源岩,其有机质丰度(TOC值)可达1.30%,所在地层厚度约为95.0m。在此基础上,进行了烃源岩井震对比及烃源岩发育层位在地震剖面上的对比追踪,最终在阿—满过渡带识别出一套附存于中奥陶统一间房组顶部—上奥陶统吐木休克组的海相烃源岩。该套烃源岩向东相变于古城—轮古东台缘西侧,向南超覆尖灭于塔中Ⅰ号断裂带下盘的满加1井附近,向西超覆尖灭于阿—满过渡带西台缘,向北沉积相变于塔北隆起区羊屋2井南部,烃源岩最大埋深达8 500m。分析认为,该套烃源岩发育于阿—满过渡带碳酸盐岩台地内凹陷环境,其厚度小于150m,应该是塔中与塔北油气区的主力烃源岩之一。更多还原

【Abstract】 No Ordovician marine source rocks have been found in the transitional zone between Awati and Manjia’er depressions,Tarim Basin.However,a large amount of geochemical data indicates that the oil/gas in the middle and northern Tarim Basin(hereafter referred to as Tazhong and Tabei) are possibly sourced from this area.In view of this,we reviewed and analyzed the TOC contents of the Middle-Upper Ordovician mudstone samples from several wells on the structural high in this area.A set of marine hydrocarbon source rocks with the TOC content up to 1.30% was preliminarily recognized in an interval with a bulk thickness of 95.0 m.On this basis,we performed well-seismic data correlation of the source rocks and tracing of the horizon with source rocks on seismic section.A set of marine source rocks was finally identified in the interval from the top Middle Ordovician Yijianfang Formation to the Upper Ordovician Tumuxiuk Formation in the transitional zone between Awati and Manjia’er depressions.This set of source rocks pinches out eastwards on the western side of the eastern margin of the Gucheng-Lungudong platform,overlaps and pinches out southwards near the Manjia-1 well in the footwall of Tazhong Ⅰfault,overlaps and pinches out on the western platform margin in the transitional zone,and pinches out northwards in the southern part of the Yangwu-2 well on the Tabei uplift.It has a maximum burial depth of up to 8500 m and a thickness of less than 150 m which was possibly deposited in an intra-platform depression within the transitional zone.It may be one of the major source rocks contributing hydrocarbons to the Tazhong and Tabei oil fields.This study is of great significance to hydrocarbon resource assessment and exploration potential evaluation.更多还原