准噶尔盆地莫西庄地区三工河组二段储层微观特征及有效储层控制因素

Reservoir microscopic characteristics and effective reservoir control factors of J_(1s_2) in Moxizhuang area, Junggar Basin

通过普通薄片和铸体薄片观察、孔隙显微图像分析、扫描电镜和阴极发光等测试手段,研究了莫西庄地区三工河组二段储层岩石学、孔隙类型和成岩作用等微观特征,分析了低渗储层的形成原因和相对优质储层的主控因素。研究结果表明:砂岩以成分成熟度较低的长石岩屑砂岩为主,含少量岩屑砂岩,软岩屑塑性变形强烈或假杂基化,对储层物性和含油性影响大;砂岩孔隙类型主要为次生溶蚀孔,其次为剩余原生粒间孔;强烈的压实作用、方解石和高岭石胶结作用是导致储层低渗的主要原因。优质储层表现为粗粒、低含量软岩屑-弱方解石和高岭石胶结-强溶蚀作用的微观特征。优质储层形成的主要控制因素包括软岩屑含量、晚期溶蚀作用和有利的沉积相带,河道砂体旋回中、下部储层是有效储层发育的有利部位。

Through the analysis of casting thin sections and pore microscopic images, combined with scanning electron microscopy and cathodoluminescence images, the reservoir microscopic characteristics of Jls2 in Moxizhuang area were studied, which included reservoir petrology, pore types, diagenesis etc. In addition, the factors responsible for the formation of low permeability reservoirs and the main controlling factors of relatively high quality reservoirs were analyzed. The results show that the sandstones are mainly feldspathic-lithic sandstones with low ingredients maturity, with a small amount of lithic sandstone. The soft debris has experienced strong plastic deformation, thus looking like matrix, which remarkably affects physical property and oil-bearing property of the reservoir. The pore type is mainly secondary pore and subordinately primary pore. Strong compaction, weak calcite and kaolinite cementation are the main factors responsible for the low permeability reservoirs. The high quality reservoirs have such microscopic characteristics as coarse grain size, low content of soft debris, weak calcite and kaolinite cementation and strong dissolution. So the main factors controlling high quality reservoirs should include the content of soft debris, late dissolution, and favorable sedimentary facies. In addition, the channel sand body cycles in the middle and lower reservoir are the favorable Darts of the effective re^erv,~i~