塔里木盆地玉北地区鹰山组储层特征及主控因素

Reservoir Characteriza tion and Controlling Factors of Lower-Middle Ordovician Yingshan Reservoir in Yubei Area, Tarim Basin

塔里木盆地玉北地区中—下奥陶统鹰山组为断控型风化壳储层,由于经历多期岩溶和断裂的综合叠加作用,加之塔里木盆地本身复杂的古地貌演化史,增加了识别岩溶改造期次的难度,同时极大地影响了储层中裂缝有效性的判断。通过相关钻井的岩心观察、薄片鉴定、地化数据分析,运用测井、地震等地球物理方法,归纳出玉北地区鹰山组四种储集岩组合类型,并研究了各类储集岩的孔渗相关性。认为研究区早—中奥陶世潜山构造带构造活动强烈,储层的形成与断裂及构造裂缝密切相关。断裂期次与加里东中期Ⅰ幕、Ⅲ幕岩溶作用在构造运动时期上的匹配,有效地改善了鹰山组顶部石灰岩地层的储集性能;埋藏白云石化作用则改善了区内鹰山组底部晶粒白云岩地层的孔隙性。

A Lower-Middle Ordovician Yingshan weathering-crust reservoir develops in Yubei area in Markit Slope, Tarim Basin. Affected on multi-stage faulting and paleo-karstification, it is difficult to identify karstification stages and fracture effectiveness. Based on observation and geochemical analysis of core samples and microscopic thin-slices, combined with logging and seismic interpretation, four assemblages of related reservoir rocks are recognized in Yingshan Formation and some correlations of porosity with permeability are diagramed for these rock assemblages. It is suggested that the reservoir property of Yingshan Formation is closely related to the early to middle Ordovician faulting and fracturing. The multi-stage faulting and the karstification experienced during Ⅰ and Ⅲ phases of Middle Caledonian movement effectively improved the reservoir property of limestone in the uppermost part of Yingshan Formation and the dolomitization improved the porosity of crystalline dolostone in the lowermost part of it.