库车坳陷三叠系塔里奇克组沉积与储层特征及油气勘探意义

Sedimentary and Reservoir Characteristics and Hydrocarbon Exploration Significance of Triassic Taliqike Formation in Kuqa Depression

塔里木盆地库车坳陷上三叠统塔里奇克组源-储共生,但勘探认识程度低,储层基础研究尚未开展.结合露头-钻井沉积特征、物性测试、薄片鉴定等资料研究认为:塔里奇克组因砂/砂砾岩与暗色泥岩或煤层交替而呈源-储互层的“三明治”结构;砂岩主要为岩屑砂岩,但随颗粒变粗,石英含量有增高的趋势;砂岩处于中成岩阶段,压实作用是最主要的减孔作用,溶蚀作用是最明显的增孔作用,储集空间类型以粒间溶孔和粒内溶孔为主;随石英颗粒含量增高,孔隙度有增加的趋势,且随着砂岩粒度变粗,孔、渗有变好的趋势;沉积相是控制储集性的关键因素,分流河道砂岩/砂砾岩是最优储层;塔里奇克组砂岩物性与巴什基其克组、阿合组等重要油气储层具有较高的相似度,在北部构造带发育较厚的Ⅱ-Ⅲ类规模性储层,且被夹持在煤层和暗色泥岩优质烃源岩中,对寻找中深层常规-非常规型构造-岩性油气藏意义重大.

The concomitant source-reservoir is developed in the Upper Triassic Taliqike Formation of Kuqa depression,Tarim Basin.However,it has not yet attracted much attention for exploration and relevant studies on the reservoir have not been initiated.Based on the comprehensive analysis of sedimentary characteristics,physical property testing,and thin section identification,results of this study show that Taliqike Formation presents a"sandwich"of source-reservoir interbeds due to the alternation of sand/glutenite stone and dark mudstone or coal seams.The compositional maturity of sandstone is low,mainly composed of lithic sandstone,but as the particles become coarser,the quartz content tends to increase.Sandstone is in the middle diagenetic stage,and the most important pore reducing effect and the most obvious pore increasing effect are compaction and dissolution,respectively.The type of storage space is mainly intragranular dissolved pores and intergranular dissolved pores,and dissolution is the main contribution of the sandstone reservoir space of the Taliqike Formation.As the content of quartz particles increases the porosity tends to increase,and as the grain size of the sandstone becomes coarser,the porosity and permeability tend to become better;sedimentary facies is the key factor to control the reservoir and the sandstone/glutenite of distributary channel is the best reservoir.The physical properties of the sandstone of Taliqike Formation are similar to other important hydrocarbon reservoirs of Bashijiqike and Ahe Formations.The thicker TypeⅡ-Ⅲlarge-scale reservoirs are developed in the northern structural belt,and they are sandwiched in high-quality hydrocarbon source rocks formed by coal seams and dark mudstones.It is of great significance to search for middle-deep conventional and unconventional structure-lithologic reservoirs.