大民屯凹陷静安堡西侧低潜山变质岩储层裂缝发育特征

FRACTURED CHARACTERISTICS OF METAMORPHIC RESERVOIRS IN LOW BURIED-HILL IN WEST OF JING'ANPU, DAMINTUN DEPRESSION

大民屯凹陷静安堡西侧低潜山储层裂缝以高角度缝为主 ,次为倾斜缝。裂缝的发育经历了中生代晚期早第三纪早、中期和早第三纪晚期两次大的形成期。物性分析表明 ,潜山变质岩储层基质孔隙度很低 ,一般只有1%～ 5 % ,渗透率大多低于 1× 10 -3 μm2 ,因此这些基质孔隙对油气储集作用非常有限 ,构造裂缝是变质岩储层的主要储集空间和运移通道。裂缝的形成与发育程度受岩性、断层、埋深及古风化作用的影响 ,随着岩石中浅色矿物的增加 ,岩石脆性成分变多 ,岩石的宏观裂缝就越发育 ;越靠近断层和构造活动区 ,裂缝发育程度就越高 ;裂缝的有效性随着埋深的增加而变差 ,甚至成为无效裂缝 ;一般来说 ,潜山风化带顶面的裂缝较发育 ,但这些裂缝容易受到泥质的充填 ,极易成为无效裂缝。因此 ,潜山风化带的储集物性并不一定好。

Metamorphic reservoir fractures in low buried hill in the west part of Jing'anpu,Damintun Depression are primarily high angle fractures.The evolution of the fractures underwent Late Mesozoicearly and middle Early Tertiary forming stage and the late Early Tertiary forming stage.Since matrix porosity of the reservoirs is only 1%～5%,and the permeability is 1×10 -3 μm 2,tectonic fractures are the main reservoir spaces and migration paths of the metamorphic reservoirs.The formation of the fractures was affected by lithologic features,faults,burial depth and paleoaeolation.In general,the reservoir property of weathered zones in the buried hill may be not so good.