乍得Doseo走滑反转盆地油气成藏特征和勘探发现  

Exploration discovery and hydrocarbon accumulation characteristics of the Doseo strike-slip and inverted basin,Chad

作　　者：窦立荣[1,2] 肖坤叶 杜业波[1] 王利[1] 张新顺[1] 程顶胜[1] 胡瑛[1] DOU Lirong;XIAO Kunye;DU Yebo;WANG Li;ZHANG Xinshun;CHENG Dingsheng;HU Ying(Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China;China National Oil and Gas Exploration and Development Corporation,Beijing 100034,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油国际勘探开发有限公司,北京100034

出　　处：《石油勘探与开发》2022年第2期215-223,共9页Petroleum Exploration and Development

基　　金：国家科技重大专项“海外重点探区目标评价与未来领域选区选带研究”(2016ZX05029005);中国石油天然气集团有限公司科学研究与技术开发项目“海外重点领域油气勘探关键技术”(2021DJ31)。

摘　　要：在乍得Doseo盆地经历多家国际油公司30多年勘探才获得重大突破。基于大量地震和钻井新资料,对盆地构造沉积及油气地质特征进行梳理,系统分析油气成藏条件与富集规律,优选有利区带指导勘探实践。综合研究认为,该盆地是在中非剪切带前寒武系结晶基底上发育的中新生代湖相裂谷盆地,为受北部边界走滑断层控制的箕状断陷,具有两坳一隆一斜坡的构造格局。白垩纪盆地发育两期裂谷,始新世发生强烈反转,抬升剥蚀厚度达到800~1000 m,之后进入拗陷-消亡期。边界断层为先正后逆的反转断层,盆内以正断层和走滑断层为主,构造样式包括花状构造、挤压背斜、断鼻和复杂断块等。盆内以早白垩世沉积为主,自下而上发育Mangara群、Kedeni组、Doba组、Koumra组,划分为两个水进-水退旋回,以湖泊-河流-三角洲/辫状河三角洲/扇三角洲相砂-泥岩沉积为主;有效烃源岩为下白垩统深湖相泥岩,有机质以Ⅰ—Ⅱ1型为主;盆内主要圈闭类型为断层复杂化的反转背斜和断块。Kedeni低凸起是最有利勘探区带,其次是北部陡坡带和南部斜坡带,断层侧向封堵性控制油气丰度。Several international oil companies had conducted petroleum exploration,but failed to make any commercially viable discoveries in the Doseo Basin for over 30 years.An integrated analysis of hydrocarbon accumulation and enrichment in the basin based on the latest seismic and drilling data combined with exploration practice,tectonic sedimentation and petroleum geological characteristics was completed to find the potential petroleum plays.The Doseo Basin in Chad is a Meso-Cenozoic lacustrine rift basin developed on the Precambrian crystalline basement in the Central African Shear Zone.It is a half graben rift controlled by the strike-slip fault at the northern boundary,and can be divided into two subbasins,an uplift and a slope.The basin experienced two rifting periods in the Cretaceous and was strongly inverted with the erosion thickness of 800–1000 m during the Eocene,and then entered the depression and extinction period.Normal faults and strike-slip faults are developed in the basin,and the boundary faults are inverted faults.The main structural style includes compressed anticlines,fault noses,complex fault-blocks and flower structures.The Lower Cretaceous is the main sedimentary strata,which are divided into the Mangara Group,Kedeni,Doba and Koumra Formations from bottom up.Two transgressive-regressive cycles developed in the Lower Cretaceous with mainly lacustrine,river,deltal,braided river delta,fan delta facies sandstone and mudstone.The effective source rock in the basin is the Lower Cretaceous deep lacustrine mudstone with the type I and type II1 organic matter.Inverted anticlines and fault complicated blocks are the main trap types.The Kedeni Uplift is the most favorable play,followed by the Northern Steep Slope and Southern Gentle Slope.Lateral sealing capacity of faults controls the hydrocarbon abundance.

关 键 词：Doseo盆地 裂谷盆地 走滑作用 反转构造 含油气系统 成藏特征 勘探发现 

分 类 号：TE122[石油与天然气工程—油气勘探]