Lower oil sand hill formation beach-bar sandstone characteristics and reservoir evaluation in Wunan-Lucaotan area,Qaidam Basin
Wang Hua-ai1, Zhong Jian-hua1, Yang Shao-yong2, Zhang Chang-hao2, Wang Jin-hua1
1. Institute of the Earth Recourses and Information,China University of Petroleum(East China),Dongying City,Shandong Province,257061,China;
2. Petrochina Qinhai Branch company,Dunhuang City,Gansu Province,736202,China
Abstract：In this paper the authors carefully and integratedly studied the deposit and distribution,reservoir characteristics and reservoir properties of Lower oil sand hill formation beach-bar sandstone in Wunan-Lucaotan area,the conclusions were reached as the following:the deposit of the beach-bar sandstone was controlled by three factors,the paleotopography,ancient lake shoreline morphology and the deposit datum,over the exploration area the beach-bar sandstone mainly distributed on wide gentle slopes and paleo-uplifts in lake basin windings and braided delta flanks under the tidal environment,vertically beach sandstone mainly deposited in short-term datum upward half-cycles while the bar sandstone mainly deposited in short-term datum downward half-cycles with thin layer,tiny throat and low permeability as their reservoir properties.The major type of the reservoir space is native intergranular pore,the reservoir properties depend on sedimentary microfacies types,diagenesis,micro-pore structure types,pore-throat sorting and other factors.In this paper the beach-bar reservoirs in Wunan-Lucaotan area,Qaidam Basin were evaluated and were divided into 3 levels,the good reservoir,the mediocre reservoir and poor reservoir.
