伊拉克东南部白垩系塞诺曼阶—下土伦阶生物碎屑灰岩层序研究进展  

Research progress on the bioclastic limestone sequence of Cretaceous Cenomanian-Lower Turonian in southeastern Iraq

作　　者：李峰峰 任立新 李蕾 万洋 陈昊卫 LI Fengfeng;REN Lixin;LI Lei;WAN Yang;CHEN Haowei(Research Institute of Petroleum Exploration&Development)

机构地区：[1]中国石油勘探开发研究院,北京市海淀区100083

出　　处：《海相油气地质》2025年第1期41-58,共18页Marine Origin Petroleum Geology

基　　金：中国石油科技重大专项课题“巨厚碳酸盐岩油藏注水开发关键技术研究与应用”(编号:2023ZZ19-01)和“ALBION碳酸盐岩储层联合研究”(编号:2021DQ0407)联合资助.

摘　　要：伊拉克东南部白垩系塞诺曼阶—下土伦阶发育巨厚生物碎屑灰岩,地层结构复杂,不同级次层序嵌套。以6个巨型碳酸盐岩油田为例,对其层序地层特征、沉积演化及控储机制进行了分析讨论:梳理了前人关于塞诺曼阶—下土伦阶层序划分的方案,采用了将其划分为4个三级层序的方案;分析总结了不整合面、淋滤溶蚀面、碳质泥岩层、沉积相转换面、沉积相突变面、最大海泛面及硬底等关键层序界面的形成机理和特征;应用适用的层序地层学理论和方法,基于塞诺曼阶—下土伦阶浅水沉积背景,建立碳酸盐缓坡-弱镶边台地层序旋回模式;揭示层序旋回与沉积演化的规律,阐明层序控储机制,厘清层序级次和层序界面对生物碎屑灰岩储层的控制,明确了海平面下降幅度、地层暴露时间和气候条件对地层结构、岩性和物性的影响。最后,指出伊拉克东南部塞诺曼阶—下土伦阶层序旋回研究存在的问题和发展趋势。研究成果为中东巨厚生物碎屑灰岩油藏分层系注水开发提供了参考依据。The Cenomanian-Lower Turonian in southeastern Iraq is characterized by thick bioclastic limestone,with complex stratigraphic structure and nested sequences of different levels.The sequence recognition is important for stratigraphic division and reservoir correlation.Thick bioclastic limestone reservoir is commonly developed by separated waterflooding,and the study of sequences can lay a geological foundation for the division of development units.Taking six giant oilfields as example,all of which developed thick bioclastic limestone as main pay formations in the Cenomanian-Lower Turonian,the sequence schemes of Cenomanian-Lower Turonian are summarized.This paper adopts the scheme of dividing the Cenomanian-Lower Turonian into four of a third-order sequence corresponding to the four maximum flooding surface(K120,K130,K135,and K140).Mechanisms and characteristics of key sequence boundary such as unconformities,leaching and dissolution,thin carbonaceous mudstone,facies transition,facies mutation,maximum flooding surface,and hardground are summarized.Southeastern Iraq is located in the northeastern margin of the Arabian Plate,and during the Cenomanian-Early Turonian it is in a stable passive continental margin environment.This paper uses the quadratic model of classical stratigraphy to study the sequences of thick bioclastic limestone.According to the sequence theory,the sequence model of slightly rimmed carbonate ramp is established based on the depositional setting of Cenomanian-Lower Turonian.Different paleogeographic locations have different water depths during the process of sea-level rise and fall,so carbonate deposition rates and petrological features have different sensitivities to sealevel changes at different location.The water background and paleogeography control the sedimentation of different oilfields in southeastern Iraq.The sequence and depositional evolution are therefore revealed.Through elucidating the mechanism of sequence,and the effects of sequence order and sequence boundary on bioclastic limest

关 键 词：生物碎屑灰岩 层序 沉积演化 层序控储 塞诺曼阶—下土伦阶 伊拉克东南部 

分 类 号：TE122.2[石油与天然气工程—油气勘探]