Sedimentary characteristics of braided delta and relationship to reservoirs in the Cretaceous of Kelasu tectonic zone in Kuqa Depression, Xinjiang
Pan Rong1, Zhu Xiaomin1, Liu Fen1, Li Yong2, Ma Yujie2, Di Hongli2, Zhang Ronghu3
1 College of Geosciences, China University of Petroleum(Beijing), Beijing102249 2 Tarim Oilfield Company, PetroChina, Korla841000, Xinjiang 3 Hangzhou Institute of Petroleum Geology, PetroChina, Hangzhou 310023, Zhejiang
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.
Pan Rong,Zhu Xiaomin,Liu Fen et al. Sedimentary characteristics of braided delta and relationship to reservoirs in the Cretaceous of Kelasu tectonic zone in Kuqa Depression, Xinjiang[J]. JOPC, 2013, 15(5): 707-716.
