摘要
天草凹陷东部斜坡白垩系巴音戈壁组二段油气资源丰富,但存在储层横向变化快、发育控制因素不明确的问题,制约了该区域油气藏勘探进程。为此,采用构造-沉积耦合研究方法,结合地震解释、古地貌恢复、岩心观察、薄片鉴定及测井相分析等技术手段,系统研究了东部斜坡构造特征、沉积储层展布规律及二者的耦合关系。研究结果表明:①天草凹陷东部斜坡发育长期活动并控制沉积的主要断裂,随构造运动持续活动,形成了断裂坡折带,该断裂坡折带明显具有控沉积的作用,造成坡折带附近地形较陡、坡折带两侧地层厚度发生突变。②巴音戈壁组二段沉积时期,东部斜坡沉积相主要为辫状河三角洲前缘,该沉积相可进一步划分内前缘和外前缘2个相带,三角洲内前缘相带距离物源较近、沉积速度快、岩石分选较差、孔渗条件不佳;三角洲外前缘相带距离物源相对较远,沉积物受湖水改造作用增强,砂体岩石分选较好,有利于孔隙的发育和连通,孔渗条件较好。③断裂坡折带与沉积相叠合分析表明,坡折带两侧沉积微相有明显的差异,其正是内前缘与外前缘的分界线,坡折带之上主要发育三角洲内前缘相带,沉积微相主要为水下分流河道,岩性较粗、分选较差、物性不佳;坡折带之下主要发育三角洲外前缘相带,沉积微相主要为水下分流河道、河口坝,岩性较细、分选较好、物性较好,是有利储层发育区。研究成果为天草凹陷及相似地质条件地区的油气藏勘探提供了理论依据和实践参考。
The eastern slope of Tiancao Sag is rich in oil and gas resources in the second Member of Cretaceous Bayingebi Formation,but faces challenges including rapid reservoir lateral changes and unclear developmental control factors,which constrain the hydrocarbon reservoir exploration progress in this area.Therefore,adopting a structure⁃sedimentation coupling research approach and integrating technical methods such as seismic interpretation,paleogeomorphology restoration,core observation,thin section identification,and log facies analysis,this study systematically investigated the structural characteristics,sedimentary reservoir distribution patterns,and their coupling relationships on the eastern slope.The results are obtained in three aspects.(1)The eastern slope of Tiancao Sag develops major long⁃term active faults that control sedimentation,which continuously move with tectonic activities,forming fault slope⁃break belts.These fault slope⁃break belts significantly control sedimentation,resulting in steeper topography near the slope⁃break belts and abrupt changes in stratum thickness on both sides of the slope⁃break.(2)During the sedimentary period of the second Member of Bayingebi Formation,the main sedimentary facies on the eastern slope was braided river delta front,which can be further divided into two facies belts of inner⁃front and outer⁃front.The delta inner⁃front facies belts is closer to the provenance,with faster sedimentation rate,poorer rock sorting,and inferior porosity⁃permeability conditions.The delta outer⁃front facies belt is relatively farther from the provenance,where sediments are more strongly modified by lake water,with better sandstone sorting,favorable for pore development and connectivity,and better porosity⁃permeability conditions.(3)Overlay analysis of fault slope⁃break belts and sedimentary facies shows significant differences in sedimentary microfacies on both sides of the fault slope⁃break belts.The fault slope⁃break belts precisely serve as the boundary between inner and outer fronts.Above the fault slope⁃break belts,the delta inner⁃front facies belt mainly develops,with sedimentary microfacies primarily being underwater distributary channels,characterized by coarser lithology,poorer sorting,and inferior physical properties.Below the fault slope⁃break belts,the delta outer⁃front facies belt mainly develops,with sedimentary microfacies primarily being underwater distributary channels and mouth bars,characterized by finer lithology,better sorting,and better physical properties,making it a favorable reservoir development area.The research findings provide theoretical basis and practical reference for hydrocarbon reservoir exploration in Tiancao Sag and similar geological conditions areas.
作者
张华
荆文波
唐鑫萍
王瑀
王港
徐雄飞
ZHANG Hua;JING Wenbo;TANG Xinping;WANG Yu;WANG Gang;XU Xiongfei(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Exploration and Development Research Institute,PetroChina Tuha Oilfield Company,Hami,Xinjiang 839099,China;Exploration and Development Research Institute,PetroChina Dagang Oilfield Company,Tianjin 300280,China;The Fourth Exploit Factory of PetroChina Dagang Oilfield Company,Tianjin 300280,China)
出处
《录井工程》
2026年第1期138-144,共7页
Mud Logging Engineering
基金
中国石油油气和新能源分公司科技项目“吐哈盆地风险勘探领域和目标研究、工程技术攻关及现场试验”(编号:2023YQXNCS001⁃09)
中国石油天然气股份有限公司攻关性应用性科技专项“深地煤层气成藏理论与效益开发技术研究”(编号:2023ZZ18)。
关键词
天草凹陷
巴二段
断裂坡折带
辫状河三角洲
储层控制
构造-沉积耦合
内前缘
外前缘
Tiancao Sag
the second Member of Bayingebi Formation
fault slope⁃break belt
braided river delta
reservoir control
structure⁃sedimentation coupling
inner front
outer front
