西非裂谷系Termit盆地白垩系砂岩成岩作用及有利储层发育区预测  

Diagenesis of Cretaceous sandstone and prediction of favorable reservoir development area in the Termit Basin of the West African rift system

作　　者：毛凤军[1] 刘计国[1] 姜虹[1] 袁圣强[1] 李早红[1] 郑凤云[1] 陈忠民[1] 程顶胜[1] 王玉华[1] Mao Fengjun;Liu Jiguo;Jiang Hong;Yuan Shengqiang;Li Zaohong;Zheng Fengyun;Chen Zhongmin;Cheng Dingsheng;Wang Yuhua(PetroChina Research Institute of Petroleum Exploration&Development)

机构地区：[1]中国石油勘探开发研究院,100083

出　　处：《中国石油勘探》2020年第4期86-94,共9页China Petroleum Exploration

基　　金：中国石油天然气集团有限公司科学研究与技术开发项目“乍得—尼日尔重点盆地勘探领域评价和目标优选”(2019D-4308)。

摘　　要：成岩作用在沉积岩形成演化过程中占有重要位置。由于不同盆地沉积及构造演化的差异性,导致其成岩作用也有不同的特点。以样品实验分析为基础,开展尼日尔Termit盆地白垩系砂岩成岩作用研究,明确了该盆地白垩系砂岩成岩作用的主要类型及其对储层的影响;根据成岩现象、黏土矿物特征与变化规律、包裹体均一温度等多个方面对该盆地白垩系砂岩储层进行成岩阶段划分,认为研究区白垩系砂岩大多处于中成岩A阶段,埋藏较浅的砂岩处于早成岩B阶段。Termit盆地白垩系砂岩的岩石类型是影响成岩作用的一个重要因素,由于该盆地白垩系砂岩以石英砂岩为主,石英颗粒的强支撑作用减弱了压实作用对储层的破坏,原生粒间孔是最为发育的孔隙类型,此外还发育少量粒内孔隙、粒间溶孔等孔隙。Termit盆地不同区带白垩系砂岩储层的发育具有一定的差异,Fana低凸起和Yogou斜坡储层相对较发育,储层物性好;Soudana隆起带和Dinga断阶储层物性差。Fana低凸起具有很好的勘探潜力,从钻探结果中也得到了证实,是后续白垩系勘探的重点区带。Diagenesis plays an important role in the formation and evolution of sedimentary rocks.Due to the differences in sedimentary and tectonic evolution in different basins,diagenesis also has different characteristics.Based on the experimental analysis of samples,the diagenesis study of Cretaceous sandstones in the Termit Basin of Niger was carried out.The main types of diagenesis of Cretaceous sandstones in the basin and its infl uence on reservoirs are clarifi ed.The diagenetic stages of Cretaceous sandstone reservoirs in the basin are divided according to diagenesis appearance,clay mineral characteristics and transformation laws,and homogenization temperature of inclusions.It indicates that most of the Cretaceous sandstones in the study area are in the phase A of middle diagenesis,and the sandstones with shallower burial depth are in the phase B of early diagenesis.The rock type of the Cretaceous sandstones in the Termit Basin is an important factor affecting the diagenesis.The Cretaceous sandstones in the basin is dominated by quartz sandstones.The strong support of quartz grains resisted the reservoir damage from compaction.The primary intergranular pore is the dominant pore type.In addition,a small number of pores such as intragranular pores,intergranular dissolved pores,and grain-edge fractures are also developed.There are some differences in the development of Cretaceous sandstone reservoirs in different zones of the Termit Basin.Reservoirs in the Fana low bulge and Yogou slope are relatively developed with good physical properties,while they are relatively poor in the Soudana uplift belt and Dinga fault terrace.There is good exploration potential in the Fana Low bulge,which has been proved by drilling results.It is the key area for future Cretaceous exploration.

关 键 词：Termit盆地 白垩系 砂岩 成岩作用 

分 类 号：TE112.2[石油与天然气工程—油气勘探]