塔河油田石炭系卡拉沙依组储层特征及其控制因素

石炭系卡拉沙依组是塔河油田的重要储油层系。储层发育程度是油气富集的关键因素之一。控制储层物性的主要因素是沉积相,沉积微相不同,成岩作用不同,储层物性不同。辫状河三角洲分流河道及厚层潮道砂体的岩性为中—粗砂岩,粒间孔及残余粒间孔发育,砂体物性好。辫状河三角洲前缘河口坝、河道间砂体、潮间带砂坪、砂坝及薄层潮道砂体的岩性以粉—细砂岩为主,储层物性差。本区砂岩总体上属低—中孔、低—高渗型储层,且以中低孔、中低渗为主。纵向上卡拉沙依组可分为5个砂层组,Ⅰ、Ⅱ砂层组及Ⅲ砂层组下部物性较好;横向上3区、4区、6区为有利及较有利储层发育区。

RESERVOIR CHARACTERISTICS AND THEIR CONTROLLING FACTORS OF THE CARBONIFEROUS KARASHAYI FORMATION IN TAHE OILFIELD

The developing degree of reservoirs is the major controlling factor of hydrocarbon accumulation of the Carboniferous Karashayi Formation, an important oil reservoir bed in Tahe oilfield. The physical properties of reservoirs are mainly controlled by sedimentary microfacies and diagenesis. The lithology of branch channel sandbodies of braided river delta and medium-bedded tidal channel sandbodies are mainly medium-coarse-grained sandstone which develops intergranular pore-space and residual intergranular space, and have well accumulation features. The lithology of sandbodies of river mouth bar of braided river delta-front, interchannel, sand flat and sand bar of intertidal zones are mainly silt sandstone and fine-grained sandstone which have worse accumulation properties. In general, sandrocks are low-medium porosity and low-medium permeability reservoirs in this area. The sand-shale segment of the Karashayi Formation can be divided into five sand sets in depth, and the sandbodies of Ⅰ, Ⅱ sand set and Ⅲ sand set have well accumulation properties. The available reservoirs developed in three areas such as 3rd, 4th and 6th block of Tahe oilfield.