乍得Bongor盆地白垩系测井特征、低阻油气层成因和分布  

Logging characteristics of Cretaceous sequence stratigraphy and the genesis and distribution of low-resistivity oil and gas layers in Bongor Basin,Chad

作　　者：毛志强[1] 姜志豪 李长文 令狐松[3,4] 张莉莉 MAO Zhiqiang;JIANG Zhihao;LI Changwen;LINGHU Song;ZHANG Lili(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;School of Earth Sciences and Engineering,Xi'an Shiyou University,Xi'an,Shaanxi 710065,China;CNPC Logging International Division,Beijing 102206,China;Well Logging Key Laboratory,CNPC,Xi'an,Shaanxi 710077,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]西安石油大学地球科学与工程学院,陕西西安710065 [3]中国石油集团测井有限公司国际事业部,北京102206 [4]中国石油天然气集团公司测井重点实验室,陕西西安710077

出　　处：《石油地球物理勘探》2022年第1期212-221,I0009,I0010,共12页Oil Geophysical Prospecting

基　　金：中国博士后基金第70批面上资助项目“地区专项资助计划”(2021MD703881);中国石油集团测井有限公司项目“乍得、尼日尔复杂油气层测井评价技术研究与应用”(2016D-4502)资助。

摘　　要：Bongor盆地在经历断陷、坳陷构造演化过程后,不同勘探区块的含油性存在差异,同时还存在非常规油气层。地层内不同油气层的电阻率变化范围大,存在低电阻率及低对比度油气层的识别难题。为此,根据岩心、测井、试油及地化分析等资料,以Bongor盆地Baobab区块和Daniela区块为主要研究对象,分析了白垩系层序地层测井特征、低阻油气层成因和分布。结果表明:①R-K、M和P组测井响应差异明显,M-P组泥岩中发育含有机质薄层源岩,其测井特征典型、易辨;Baobab、Daniela等区块M组具有快速沉积超压测井响应特征。②自生自储的P组为白垩系的主要含油气层组。③M-P组存在二类低阻油气层(第一类为薄砂层或薄泥质砂层,第二类为非常规油气层)及一类低对比度油气层,其中低阻油气层主要发育在M组底部或P组顶部,具有源内或近源成藏特征,当存在地层超压特征时,一般具有很高的自然产能;低对比度油气层主要发育于P组主力油层中下部,对应层段中的水层具有天然水淹痕迹,电阻率普遍较高,接近甚至高于相邻的油层电阻率。After multi-stage structural evolution of faults and depressions in Bongor Basin,differences occur in oil-bearing properties of different fault depressions,and there are also unconventional oil and gas reservoirs.The resistivity of oil and gas reservoirs varies widely,and it is difficult to identify oil and gas reservoirs with low resistivity and low contrast.Therefore,according to the data of core,logging,oil test and geochemical analysis,this paper analyzed the logging characteristics of Cretaceous sequence stratigraphy,as well as the genesis and distribution of low-resistivity oil and gas reservoirs,with Baobab Block and Daniela Block in Bongor Basin as the main research objects.The results show that:1 The logging responses of R-K,M and P Formations are obviously different.The mudstone of M-P Formation develops source rocks with thin organic matter layers,and its logging characteristics are typical and easy to distinguish.M Formation in Baobab,Daniela and other blocks exhibit rapid sedimentary and overpressure logging.2 Self-generation and self-storage P Formation is the main oil-bearing formation of Cretaceous system.3 There are two types of low-resistivity oil and gas reservoirs in M-P Formation(The first type is the thin sand layer or thin argillaceous sand layer,and the second type is the unconventional oil and gas reservoir.)and one type of low-contrast oil and gas reservoir.The low-resistivity oil and gas reservoirs are mainly developed at the bottom of M Formation or the top of P Formation,showing inside source or near source accumulation and possessing extremely high natural productivity under formation overpressure.The low-contrast oil and gas reservoirs are mainly developed in the middle and lower part of the main oil layer of P Formation.The water layer of the corresponding formation is marked with flooding,and the resistivity is generally high,close to or even higher than the that of adjacent oil layer.

关 键 词：Bongor盆地 层序地层 测井响应特征 低阻油气层 低对比度油气层 

分 类 号：P631[天文地球—地质矿产勘探]