苏丹Muglad盆地中南部西斜坡沉积层序及有利地层圈闭预测  

Sedimentary sequence and prediction of favorable stratigraphic traps in the western slope zone of the southern-central Muglad Basin,Sudan

作　　者：冉怀江 范乐元 孔庆东 续晓璟 RAN Huaijiang;FAN Leyuan;KONG Qingdong;XU Xiaojing(International Logging Company of CNPC Great Wall Drilling Company,Beijing 100101,China)

机构地区：[1]中国石油长城钻探工程有限公司国际测井公司,北京100101

出　　处：《地学前缘》2021年第1期131-140,共10页Earth Science Frontiers

基　　金：中国石油天然气集团公司海外重大科技项目“海外天然气藏复杂储层精细评价与预测技术(2018D-4305)”。

摘　　要：苏丹Muglad盆地油气资源丰富,是重要的油气探区。盆地中南部西斜坡位于Kaikang坳陷西部斜坡带,是Muglad盆地重要的勘探区之一。研究区在构造转型时期遭受严重剥蚀,目前残余地层厚度约为5000 m。受区域构造活动的影响,研究区的沉积储层发育演化与构造演化密切相关。随着构造圈闭勘探进入中后期,寻找新的勘探领域和目标已成为当务之急。因此,岩性地层圈闭勘探已成为研究区目标转换的重要途径。目前,对Muglad盆地中南部西斜坡层序地层结构等基本问题的认识还不够系统,制约了研究区油气勘探的进程。综合利用岩心、测井及地震等资料,运用层序地层学原理,在苏丹Muglad盆地中南部西斜坡层序地层格架划分的基础上,重点对沉积层序演化特征及其控制因素进行了分析。同时,探讨了有利生储盖组合,并预测和评价了有利地层圈闭。主要成果及认识如下:(1)Muglad盆地经历了3次裂谷断陷活动及其后裂谷期的3次热沉降坳陷活动,形成了6个二级层序;在二级层序格架内将白垩系Abu Gabra组至古近系Adok组划分为13个三级层序,每个层序的充填和演化都受区域构造控制。(2)研究区地层发育经历了三期断坳作用,各阶段盆地均保持了其构造背景下的沉积特征,不同阶段构造控沉积作用差异明显。通过对Muglad盆地中南部西斜坡岩心、测井、地震及古水流分析,认为研究区在断陷期主要发育湖泊及辫状河三角洲沉积体系,坳陷期主要发育辫状河及三角洲等沉积体系。由于湖盆多期次的扩张与收缩,沉积体系在时空分布上具有继承性和差异性。(3)根据Muglud盆地中南部西斜坡白垩系古近系烃源岩、储层和盖层形成的先后顺序及其空间组合关系,研究区可识别划分出四套生储盖组合。它们的成藏方式不同,主要包括两种类型的生储盖组合,即下生上储型和自生自储型。研究区以The Muglad Basin in Sudan is rich in oil and gas resources and currently is under intensive hydrocarbon exploration.The western slope of the southern-central part of the basin in the western slope zone of the Kaikang depression is one of the important exploration areas in the Muglad Basin.At present,the thickness of the remaining strata is about 5000 m as a result of severe denudation during the structural transformation period.Influenced by regional tectonic activities,the evolutionary development of the sedimentary reservoir in the study area is closely related to the tectonic evolution.In the study area,as exploration for tectonic traps entering the middle and late stages,finding new exploration fields and targets has become an urgent task,for which litho-stratigraphic trap exploration becomes an important approach.Currently,the major factor limiting oil and gas exploration is lacking a systematic understanding of the basic issues,such as the sequence stratigraphic structure of the western slope of the southern-central Muglad Basin.Here,we focused on the evolutionary characteristics of the sedimentary sequence of the western slope zone and their controlling factors through a comprehensive analysis of seismic,well logging and core data using the principle of sequence stratigraphy.We discussed the favorable source-reservoir-cap assemblage and predicted and evaluated the favorable stratigraphic traps in the study area.The main results and achievements are as follows:1)The basin experienced three large rift movements and three post-rift thermal subsidence depression movements,which resulted in six secondary sequences.In this secondary sequence stratigraphic framework,the target formations,from Abu Gabra to Adok,were divided into thirteen third-order sequences.The filling and evolution of each sequence was controlled by regional tectonic background.2)Stratigraphic development in the study area experienced three stages of rift-depression while the basin maintained its sedimentary characteristics under the control of

关 键 词：沉积层序 地层圈闭 Muglad盆地西斜坡 苏丹 

分 类 号：P618.130.2[天文地球—矿床学] P539.2[天文地球—地质学]