伊拉克南部白垩系层序格架与沉积特征  

Sequence stratigraphic framework and sedimentary evolution of the Cretaceous in southern Iraq

作　　者：韩海英[1] 郭睿[1] 王君[1] 秦国省 孙晓伟 余义常 苏海洋[1] 高阳 HAN Haiying;GUO Rui;WANG Jun;QIN Guosheng;SUN Xiaowei;YU Yichang;SU Haiyang;GAO Yang(Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China;PetroChina Hangzhou Research Institute of Geology,Hangzhou 310023,China;China National Oil and Gas Exploration and Development Company Ltd.,Beijing 100034,China;Strategic Research Center of Oil and Gas Resources,Ministry of Natural Resources,Beijing 100034,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油杭州地质研究院,浙江杭州310023 [3]中国石油国际勘探开发有限公司,北京100034 [4]自然资源部油气资源战略研究中心,北京100034

出　　处：《地学前缘》2023年第2期122-138,共17页Earth Science Frontiers

基　　金：国家科技重大专项“伊拉克大型生物碎屑灰岩油藏注水开发关键技术研究与应用(2017ZX05030-001)”;中石油集团公司重大专项“伊拉克低渗孔隙型生屑灰岩油藏储层表征及高效开发技术研究(2019D-4410)”。

摘　　要：白垩系是伊拉克南部油气勘探开发生产的重要目的层,但各大油田之间缺乏系统的层序地层研究,制约了开发生产的精细部署,因而开展层序地层和沉积体系研究具有重要的理论和实践意义。本文以层序地层学及沉积学理论为指导,依据岩心、录井、测井及地震等资料,对层序边界进行识别并对层序进行划分,分析了伊拉克南部白垩系沉积体系的演化特征。研究认为伊拉克南部白垩系以生物碎屑灰岩沉积为主,层序界面有不整合面、暴露面、岩性突变面及沉积相转换面等类型,据此可划分为两个一级层序(AP8,AP9)、6个二级层序(SS1-SS6)、22个三级层序(SQ1-SQ22),单个三级层序持续2~4 Ma不等。下白垩统划分为3个二级层序:SS1自南向北发育了内缓坡到深水盆地的沉积体系,自下而上为由盆地泥晶灰岩渐变到内缓坡颗粒灰岩的沉积序列;SS2下部沉积自西南向东北由三角洲砂岩渐变为深水陆棚碳酸盐岩,上部发育了盆地泥灰岩到浅水陆棚碳酸盐岩的沉积序列;SS3下部自西南向东北由辫状河粗砂岩演变为浅海相细砂岩,上部发育海相碳酸盐岩的沉积序列。上白垩统划分为3个二级层序:SS4自西向东发育了从深水陆棚到浅水碳酸盐岩缓坡-台地沉积,纵向上看为水体逐渐变浅的沉积序列;SS5发育以细粒碳酸盐岩为主的缓坡沉积体系,浮游有孔虫灰岩占主导地位;SS6发育了三期向上变浅的缓坡碳酸盐岩沉积序列,顶部发育陆棚相白云岩。碳酸盐岩缓坡滩、台地边缘滩和两期陆源碎屑砂体是最有利的勘探开发对象。构造活动对内缓坡滩和台地边缘礁滩的发育及分布具有重要的控制作用。The Cretaceous is an important exploration and development target in southern Iraq. However, a lack of systematic sequence stratigraphic study among major oilfields has greatly restricted fine planning for the oilfield development and production. Therefore, it has great theoretical and practical significance to investigate the sequence stratigraphy and sedimentary systems in the study area. Here, guided by sequence stratigraphy and sedimentology theory, and based on the core data, mud logs, well logs and seismic data, the sequence boundaries are identified and sequences are delineated;meanwhile the evolutionary characteristics of the sedimentary system are analyzed. According to the results, the Cretaceous in southern Iraq is mainly composed of skeletal limestone, and the sequence interface types include unconformity, exposed surface, lithology abrupt surface and sedimentary facies transition surface types. The Cretaceous is divided into 2 first-level sequences(AP8, AP9), 6 second-level sequences(SS1-SS6) and 22 third-level sequences(SQ1-SQ22);the duration of each 3sequence varies from 2-4 Ma. In the Lower Cretaceous, SS1 develops, from south to north, ramp-to-basin sedimentary system, and sediments evolve upward from basinal mudstone to inner ramp grainstone;sediments of the lower SS2 gradually evolve, SW-NE, from delta sandstone to deep-water shelf carbonates, while sediments of the upper part evolve from basinal mudstone to shallow-water shelf carbonates;and in SS3, sediments of the lower part evolve, SW-NE, from braided river coarse sandstone to shallow sea fine sandstone, while marine carbonate rock develops in the upper part. In the Upper Cretaceous, SS4 develops, from west to east, upward shallowing depositional successions of deep shelf-shallow water carbonate ramp-platform sedimentary systems;while fine-grained carbonate ramp sedimentary system, dominated by planktonic foraminifera limestone, develops in SS5;and in SS6, shallowing upward carbonate ramp sedimentary system develops in three stages, and she

关 键 词：白垩系 伊拉克 层序地层 沉积演化 生物碎屑灰岩 

分 类 号：P534.53[天文地球—古生物学与地层学] P539.2[天文地球—地质学] P618.13