塔里木盆地天山南缘区带古近系苏维依组沉积储层研究

摘要

Sedimentary facies and hydrocarbon reservoirs from the Palaeogene Suweiyi Formation in southern Tianshan Mountains, Tarim Basin, Xinjiang are examined on the basis of lithologic and physical properties of the hydrocarbon reservoirs. The Suweiyi Formation is separated into two parts:sandstone intervals in the lower part and gypsum mudstone intervals in the upper part, and composed of braided delta and lake depositional systems. The hydrocarbon reservoirs mostly consist of siltstone, fine-grained sandstone, medium-grained sandstone, and gravel-bearing sandstone, including feldspar quartz sandstone and lithic feldspar sandstone. The porosity types contain the primary intergranular pores and solution openings, and cracks and microcracks. On the whole, the basal sandstones especially the delta front distributary channel and sheet sandstones with excellent physical properties belong to the medium-porosity and medium-to low-permeability reservoirs with heavy heterogeneity. The main influencing factors include sedimentary facies and diagenesis in which compaction, dissolution and cementation are believed to be the main diagenetic effects.%根据钻井、测井与分析测试等资料，研究了塔里木盆地天山南缘区块北带苏维依组的沉积相带和储层特征。苏维依组分为下部底砂岩段和上部的膏泥岩段，在研究区主要发育辫状河三角洲和湖泊沉积体系。本区储层多为粉砂岩、细砂岩、中砂岩和含砾砂岩，主要岩石类型为长石石英砂岩和岩屑长石砂岩。孔隙类型主要是原生粒间孔、溶蚀孔，还有裂缝和微孔隙等。底砂岩段储层物性较好，总体属于中孔-中、低渗储层，非均质性较强，其中以三角洲前缘的分流河道和席状砂微相砂体物性最好。影响研究区储层物性的主要因素有沉积相带、成岩作用等，压实作用、溶蚀作用和胶结作用是对储层物性影响最大的成岩作用。