Abstract: The Member 1 and Member 2 of Bashijiqike Formation mainly comprised a set of terrigenous clastic rocks including fine sandstone, moderate-coarse sandstone, pebbled sandstone, siltstone and mudstone of Kelasu tectonic zone in Kuqa Depression, Xinjiang. Based on the analysis of data of well logging, thin section, grain size and core observation of over 30 wells(include 6 new cored wells), together with data of regional geology,|it was confirmed that there existed typical deposits of braided delta in the Bashijiqike Formation in Kelasu tectonic zone. The braided delta was characterized by composition of lithic sandstones, sedimentary structures such as wedge-shaped cross bedding and scour-and-fill tectonic formed by strong hydropower and several non-continuous normal cycles vertically, large sandbodies extended far towards the central basin, high sand-shale ratio, and the main microfacies were braided subaqueous distributary channel and subaqueous inter-distributary channel and mouth bar. According to lithologic characteristics, sedimentary structures and sedimentary sequence of the braided delta, a depositional model for the braided delta was established. The large delta front was well developed in the study area under the stable tectonic backgrounds with open basin and rich sediment supply. Subaqueous distributary channel deposits were well developed with the best physical property, and sand bodies extended towards the center of the basin for 35～60 km with good vertical and horizontal connection, so that it could be favorable reservoir space for lithologic reservoirs.

Key words: Kuqa Depression, Bashijiqike Formation, braided delta, sedimentary characteristics, depositional model, reservoir

摘要： 新疆库车坳陷克拉苏冲断带白垩系巴什基奇克组一、二段是一套由细砂岩、中粗砂岩、含砾砂岩、粉砂岩及泥岩组成的碎屑岩组合。通过30余口钻井(包括6口新取心井)的岩心、测井、录井、薄片及粒度等资料的分析, 结合区域地质资料, 确认克拉苏冲断带巴什基奇克组一、二段发育砂质辫状河三角洲沉积。其岩性以岩屑砂岩为主；粒度概率曲线具有牵引流特征；砂体中发育楔状交错层理及冲刷、充填构造等丰富的强水动力沉积构造及间断正韵律；砂体延伸远、面积大展布稳定, 砂地比值高；发育水下分流河道、分流间湾等微相。据三角洲砂体的岩性、沉积构造及沉积序列等特征, 建立了三角洲沉积模式。稳定的构造背景、开阔的盆地、丰富的物源供给使得研究区辫状河三角洲前缘沉积非常发育, 其以水下分流河道沉积为主体, 物性好, 砂体延伸远, 可向盆地中央方向推进35～60km, 砂体纵横叠置, 为岩性油气藏的形成提供了有利的储集空间。

关键词: 库车坳陷, 巴什基奇克组, 辫状河三角洲, 沉积特征, 沉积模式, 储集层

CLC Number: 

• P512.2

• TE122.2＋1