乍得邦戈盆地Baobab构造带形成演化及油气成藏控制因素  

Formation and evolution of Baobab structural zone and controlling factors of hydrocarbon accumulation in Bongor Basin,Chad

作　　者：王利[1] 张新顺[1] 肖坤叶[1] 王林 杜业波[1] 王玉华[1,2] 梁巧峰 Wang Li;Zhang Xinshun;Xiao Kunye;Wang Lin;Du Yebo;Wang Yuhua;Liang Qiaofeng(PetroChina Research Institute of Petroleum Exploration&Development;China National Oil and Gas Exploration and Development Corporation Ltd.)

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

出　　处：《中国石油勘探》2022年第2期84-92,共9页China Petroleum Exploration

基　　金：中国石油天然气股份有限公司科学研究与技术开发项目“海外复杂裂谷盆地精细勘探关键技术研究”(2021DJ3103);中国石油国际勘探开发有限公司项目“海外重点风险勘探领域评价与目标优选”(2021-167)。

摘　　要：Baobab构造带位于中非裂谷系邦戈盆地东北部斜坡,相对远离现今盆地中心,却是盆地油气最为富集的区带,深入分析该区构造演化特征与油气成藏控制因素,可为中非裂谷系油气勘探提供良好借鉴。通过研究Baobab构造带演化历史,结合油气分布特征,分析油气成藏控制因素。研究结果表明,Baobab构造带先后经历了前断陷期、断陷期、坳陷期、反转期和消亡期5个主要演化阶段。盆地断陷内稳定分布的下白垩统深湖—半深湖相M组和P组泥岩,既是主要烃源岩,又是良好的区域盖层。晚白垩世反转期发生大规模的构造反转和地层剥蚀,在Baobab构造带形成一系列背斜或断背斜圈闭,有利于油气聚集。在构造高部位或凸起带,发育以基岩风化壳和裂缝发育带储层为主的潜山油藏,圈闭形成、油气运移和储层改造均受断裂活动的控制;靠近凸起带的次洼中,发育浊积水道和扇三角洲砂岩储层为主的P组油藏,成藏明显受构造和岩性双重控制;整体上形成凸起带以基岩潜山油藏为主、次洼带以源内P组油藏为主的油气分布规律。Baobab structural zone is located in the slope of northeastern Bongor Basin, Central African Rift System. Although it is relatively far away from the basin center, the exploration practice shows that it is the most proliferous area in Bongor Basin. A detailed analysis on structural evolution and controlling factors of hydrocarbon accumulation will provide good reference for petroleum exploration in the Central African Rift System. The structural evolution and oil and gas distribution characteristics in Baobab structural zone are studied to identify the controlling factors of hydrocarbon accumulation. The results show that Baobab structural zone has experienced five main evolution stages,i.e., pre-rift stage, rift stage, depression stage, inversion stage and extinction stage. The deep lacustrine mudstones of the Lower Cretaceous M and P Formations are stably distributed in the rift basin, which are not only the main source rocks, but also good regional caprocks. A series of anticline or fault anticline traps were formed in Baobab structural zone affected by the large-scale structural inversion and strata denudation during the inversion period in the Late Cretaceous, which was conducive to the hydrocarbon accumulation. In the structural highs or bulge areas, buried hill oil reservoirs are developed mainly in bedrock weathering crust and fracture development zone, of which the trap formation,hydrocarbon migration and reservoir transformation are controlled by fault activities. While in subsags close to the bulge area, turbidite channel and fan delta sandstone reservoirs are developed of P Formation, forming oil reservoirs controlled by structure and lithology. As a whole, oil and gas distribution law is characterized by bedrock buried hill oil reservoir in the bulge area, while inside-source P Formation oil reservoir in the subsag area.

关 键 词：邦戈盆地 Baobab构造带 基岩潜山 构造反转 油气成藏 

分 类 号：TE122.1[石油与天然气工程—油气勘探]