准噶尔盆地四棵树凹陷头屯河组孔-缝双重介质致密砂岩储层特征分析

Analysis of Characteristics of Tight Sandstone Reservoir with Porous-Fissure Dual Medium in Toutunhe Formation of Sikeshu Sag

综合利用岩芯、露头和测井资料,恢复准噶尔盆地四棵树凹陷头屯河组的沉积环境,对致密砂岩储层进行岩相学、储集空间种类和成岩作用分析,并分析影响储层性能的主要因素。结果表明,四棵树凹陷头屯河组孔-缝双重介质型致密砂岩储层具有"三低一弱"的特征:低成分成熟度,低泥质含量,较低胶结物含量,较弱的溶蚀作用。孔隙主要由残余粒间孔及少量粒内溶孔组成,裂缝主要为层理缝和成岩缝。控制四棵树凹陷头屯河组致密砂岩储层物性的主要因素为沉积环境、埋藏过程、压实作用以及构造作用。发育于高泉背斜和西湖背斜中的辫状河三角洲前缘的致密砂岩储层具有良好的勘探前景,具有少量塑性颗粒含量的中-粗砂岩物性较好。储层物性主要受压实作用控制,溶蚀增孔和胶结减孔作用较弱,裂缝发育层段储层的物性较好。

Synthesizing core,outcrop,drilling data,the sedimentary environment was reconstructed.The petrography analysis,reservoir space category summary,diagenesis recovery and controlling factors of the reservoir analysis were conducted.The tight sandstone reservoir with dual medium in Toutunhe formation fractures of Sikeshu sag has the characteristics of"three low one weak"of low component maturity,low shale content and lower cement content.The pore type is mainly composed of remaining intergranular pores and a few intragranular pores and fissure types mainly consist of bedding fissures and diagenetic fissure.The principal elements controlling the tight sandstone reservoir property of in Toutunhe formation fractures of Sikeshu sag are depositional environment,burial process,compaction and tectonism.The tight sandstone reservoir with braided river delta front subfacies that developed in the Gaoquan anticline and West Lake anticline has favorable prospect for exploration.The coarse sandstones with a small amount of plastic grain content possesses better reservoir quality.The reservoir is mainly controlled by compaction.Denudation pore increasing and cementation hole reduction is limited.Fissures improve reservoir properties effectively.