河套盆地临河坳陷构造特征及油气勘探有利区分析

Structural features and favorable areas of the Linhe depression in Hetao Basin,Inner Mongolia

河套盆地临河坳陷是重要的油气勘探区域,本文从构造特征角度研究临河坳陷油气分布规律。针对河套盆地临河坳陷地区横向变化快、钻井资料少、局部构造复杂的特点,利用钻井、地质露头与重、磁、电等非地震资料,综合标定解释,建立区域解释格架,明确了研究区地层展布特征;通过构造解释和变速成图技术,精细刻画了主要目的层的构造特征,进一步明确研究区的构造格局。研究表明:(1)吉兰泰-杭锦后旗地区由南向北可划分为5个次级构造单元,且被狼山、庆格勒图、双井子、敖包、杭锦后旗一号及杭五6大断裂分隔,形成"两隆两凹一斜坡"的构造格局。(2)河套盆地形成于白垩纪早期,古近纪进入发展期。早白垩世至渐新世,沉积中心由西南向东北迁移;且白垩纪和古近纪原型盆地具备良好的成藏条件,如果后期保存较好,能够形成一定规模的自生自储型或潜山型油气藏。研究结果可为该区块或邻区的勘探与开发提供理论基础。

The Linhe depression in Hetao Basin is an important area for oil and gas exploration,and the structural features are the basis for studying the distribution law of oil and gas in the Linhe Depression. In view of the rapid lateral change,few drilling data and complex local structure in the Linhe depression,we established the regional interpretation framework,and determined the characteristics of strata distribution in the study area according to drilling,geological outcrops and non-seismic data such as gravity,aeromagnetic and electric. Structural interpretation and variable velocity mapping were utilized to identity the fine structural features of the main target layer and structural pattern of the study area. The results show that:( 1) The Jilantai-Hangjinhouqi area can be divided into five sub-structural units from south to north,which are separated by six major faults,i. e.,Langshan,Qinggeletu,Shuangjingzi,Aobao,Hangjinhouqi No. 1 and Hangwu faults,forming a structural pattern of "two uplifts,two concaves and one slope".( 2) The Hetao Basin was formed in the Early Cretaceous and entered its developmental period in the Paleogene. From the Early Cretaceous to the Oligocene,the depositional center migrated from the southwest to the northeast,and the Cretaceous and Paleogene prototype basins have good reservoir-forming conditions. If they were well preserved in the later stage,they can form a self-source and self-reservoir or buried-hill type oil and gas reservoirs of certain scale. The research results can provide a theoretical basis for the exploration and development of the block or adjacent region.