库车前陆乌什凹陷东部构造—岩性油气藏储层物性及含油性主控因素

The main controlling factors of reservoir physical property and oiliness in the structurallithologic reservoirs in the east of Wushi Sag,Kuqa foreland basin

库车前陆盆地乌什凹陷东部依拉克凝析气藏和神木1油藏为构造—岩性油气藏,白垩系舒善河组储层沉积相及物性变化快,油气水关系复杂,储层物性和含油性控制因素不清。根据常规储层物性分析、基于高压压汞和氮气吸附的微观孔喉分析和储层定量荧光对含油性的定量分析结果,对储层物性和含油性的主控因素进行了分析。研究表明:储层沉积相、岩性是控制储层物性的关键因素,沉积相上以扇三角洲前缘河口坝微相、分流河道微相和辫状河三角洲前缘分流河道微相的储层物性最好,岩性上以位于扇三角洲前缘亚相的粗、中砂岩储层物性最好。研究区本地无烃源岩,油气从东部的塔拉克地区经不整合面—断裂输导体系组合长距离运移至乌什地区,储层含油性一方面受沟通油气源的断裂控制,油气主要聚集在断裂附近的局部高部位;另一方面受储层物性的控制,在油气藏内部同一砂组范围内储层物性控制了含油性差异。往研究区东部即油气来源的方向,寻找有利的构造—岩性圈闭是该区下一步的勘探方向,加强目的层构造图和砂体沉积相的精细刻画是该区勘探开发研究的关键。

The Yilake condensate gas reservoir and Shenmu-1oil reservoir are structural-lithologic reservoirs in the east of Wushi Sag,Kuqa foreland basin.The sedimentary facies and physical properties of the Cretaceous Shushanhe Formation had a very fast change,and the distribution of oil,gas and water is very complex.The controlling factors of reservoir physical properties and oiliness are unclear,which were analyzed in this paper,based on conventional reservoir physical property analysis,micro pore throat analysis by Nitrogen Adsorption and Mercury Injection experiment,and the oiliness analysis by Quantitative Fluorescence Technique.The result shows that reservoir sedimentary facies and lithology are the key factors to control reservoir physical properties.Themouth bars,distributary channelsin fan delta front and braided delta front deposits are better than other sedimentary facies.The gritstone and medium-grained sandstone in fan delta front have the best physical properties.The study area has no native source rock,hydrocarbon migrates a long distance from the east Talake area to Wushen area through the unconformity-fault pathway combination,so there are two factors controlling the oiliness of reservoirs.One is the fault that controls oil and gas migration,hydrocarbon accumulate in the local high positions near fault;the other is the physical property of reservoir,in the same sand sets reservoir physical property controls the oiliness.The favorable structural-lithologic traps are the next exploration direction to the east of Wushi Sag,the direction to petroleum sources.Meticulous depiction of local structure map and sand body is the key for the exploration and development in the study area.