鄂尔多斯盆地陇东地区前侏罗纪古地貌恢复及油气富集规律  

Pre-Jurassic Paleogeomorphic Restoration and Hydrocarbon Enrichment in Longdong Area,Ordos Basin

作　　者：马婷钰 史立川[3] 程党性[3] 王首良 段祎乐 李元昊 Ma Tingyu;Shi Lichuan;Cheng Dangxing;Wang Shouliang;Duan Yile;Li Yuanhao(School of Earth Sciences and Engineering,Xi'an Shiyou University,Xi'an Shaanxi 710065;Shaanxi Key Laboratory of Petroleum Accumulation Geology,Xi'an Shiyou University,Xi'an Shaanxi 710065;Exploration and Development Research Institute of PetroChina Changqing Oilfield Company,Xi'an Shaanxi 710018)

机构地区：[1]西安石油大学地球科学与工程学院,陕西西安710065 [2]西安石油大学陕西省油气成藏地质学重点实验室,陕西西安710065 [3]中国石油长庆油田分公司勘探开发研究院,陕西西安710018

出　　处：《中外能源》2023年第1期33-41,共9页Sino-Global Energy

摘　　要：古地貌的研究对侏罗纪早期延安组油藏的分布及成藏规律起着至关重要的作用。以陇东地区为例,通过测井、地震以及基础地质图件等资料,采用印模法进行古地貌恢复,重点对研究区地层厚度≥80m以上的河道进行精细刻画。研究认为:三叠纪末期鄂尔多斯盆地经历了两次构造抬升运动;陇东地区发育古河谷、古斜坡、河间丘、古高地古地貌单元;古河河道并非平直对称,而是由不同深度和规模的河道和河间丘组成,甘陕古河底界发育三个北东向展布的连续型低凸起带,庆西古河河间丘较少发育;古地貌控制了富县组、延10段沉积相以及砂体展布特征,通过分割砂体以及作为沉积物的载体间接影响储层的分布特征,在古地貌形态上差异性压实产生的鼻状隆起以及后期形成的披盖压实构造形成良好的油气储集空间,与此同时,河谷单元中的不整合面以及厚层砂体为油气提供了高效的运移通道。古地貌的进一步恢复为陇东地区侏罗系早期油气勘探提供了地质依据。The study of palaeogeomorphology plays an important role in the distribution and accumulation of oil reservoirs in Yan′an Formation in the early Jurassic.Taking the Longdong area as an example,the palaeogeomorphology was restored using the impression method based on logging,seismic and basic geological maps and other data,focusing on the fine portrayal of the river channel with the stratum thickness larger than 80m in the study area.The study shows that the Ordos Basin experienced two tectonic uplift movements in the end of the Triassic.Palaeogeomorphic units including paleovalley,palaeoslope,inter river mounds,paleo-highland developed in Longdong area.The ancient river channel is not straight and symmetrical,and it consists of river channels and inter river mounds with different depths and scales;three continuous low uplift belts extending in the northeast direction developed at the bottom of the Gansu-Shaanxi ancient river,and few inter river mounds developed in the Qingxi ancient river.The palaeogeomorphology controls the sedimentary facies and sand body distribution characteristics of Fuxian Formation and Yan10 Member.The distribution characteristics of the reservoirs are indirectly affected by dividing the sand body and acting as the carrier of the sediments.The nose shaped uplift produced by differential compaction in the palaeogeomorphology and drape compaction structure formed at later stage form a good oil and gas reservoir space.At the same time,the unconformity surface and thick sand bodies in the valley unit provide efficient migration pathways for oil and gas.Further restoration of paleogeomorphology provides a geological basis for early Jurassic oil and gas exploration in the Longdong area.

关 键 词：古地貌 侏罗系 延安组 油气聚集 

分 类 号：P618.13[天文地球—矿床学]