乌什凹陷东部中生界储集层特征及控制因素

Characteristics and Controlling Factors of Mesozoic Reservoirs in Eastern Wushi Sag,Tarim Basin

据钻井岩心、薄片及物性分析资料认为,乌什凹陷中生界储集岩以岩屑砂岩为主;储集空间以粒间溶孔、粒内溶孔和晶间孔为主,仅发育少量裂缝孔隙,总体上为中低孔隙度、低渗透率储集层。研究区内辫状河三角洲平原、辫状河三角洲前缘以及扇三角洲前缘砂体为储集层发育的优势岩相,而溶蚀作用是最重要的建设性成岩作用;以黏土填隙和颗粒支撑的砂岩是有利的储集层,沟通油源的大断层附近易形成有利的油气圈闭。

Based on detailed core observation, thin-section identification and sample analysis and test of 5 wells drilled in Wushi sag of the west end of Kuqa depression in Tarim basin, it is recognized that the Mesozoic reservoir in this sag are all clastie rocks, dominated by debris sandstone; the reserwfir spaces are dominated by intergranular dissolution pore, intragranular pores and intercstal pore, with a few fracture pore, belonging to a medium-low porosity and low permeability reservoir as a whole. Comprehensive analysis reveals that the development of the reservoir is obviously controlled by the sedimentation and diagenesis. And the braided river delta plain sand body, the braided river delta front sand hody and the fan delta front sand body are its dominant lithofacies, while the dissolution is the most important constructive diagencsis. It is concluded that the clay interstitial and grain supporied sandstone could be the most fawrable reservoir and the adjacent major faults which communicate with the oil source is easy to form advantageous hydrocarbon traps in this area.