三塘湖盆地上石炭统火山岩风化壳油气藏成藏模式

VOLCANIC ROCKS WEATHERING CRUST RESERVOIR RESERVOIR MODEL OF UPPER CARBONIFEROUS IN SANTANGHU BASIN

三塘湖盆地石炭系火山岩风化壳储层是吐哈油田近年来油气勘探的重要目标。根据该区钻测井、分析化验资料揭示的火山岩风化壳剖面以及其岩石学特征、物性特点,在纵向上划分为风化粘土层(沉积盖层)及致密火山岩盖层、强风化碎石层(风化壳上带)、弱风化块石层(风化壳下带)及未风化岩石层(致密火山岩带)。有效的储集空间发育在强风化碎石层及弱风化块石层。根据火山岩储集层的孔隙成因及火山岩与烃源岩、盖层的匹配关系,将该区火山岩风化壳储层划分为两种模式:其一是下部为上石炭系哈尔加乌组内部炭质泥岩、泥岩作为烃源岩,上部卡拉岗组火山岩风化壳以淡水溶蚀孔隙与洞缝作为储层,上部的碎屑岩为盖层;构成了良好的生储盖组合;其二是哈尔加乌组内部存在的风化壳组合,风化壳中淡水溶孔和有机酸溶孔作为储层,上部致密火山岩为盖层。该模式的建立对下一步三塘湖盆地寻找火山岩风化壳储层具有重要意义。

Weathering crust reservoir of Carboniferous volcanic rock was the oil and gas exploration significant target recently years in the Santanghu basin of Tuha oil field.According to Drilling,Logging and the analysis chemical examination material revelation,volcanic rock crust of Weathering section plane as well as its petrology,the natural characteristic,thought this crust of weathering in vertical may divide it into weathered clay layer(sedimentary cover) and Dense volcanic cover,highly weathered detritus,(the upper belt of Weathering crust),weakly weathered block layer(the bottom belt of Weathering crust) and non -weathering rock(dense volcanic belt).Effective reservoir space growth in highly weathered detritus and weakly weathered block layer.According to the pore of volcanic rock reservoir and the relations of the hydrocarbon source rock of volcanic rock,divided the area weathering crust reservoir into two class:One is on the C2h for internal carbonaceous mudstone,shale as source rocks,volcanic rocks of the upper part of C2k weathering crust to freshwater corrosion slit pore with the hole as a reservoir,the upper for the cover of the clastic rocks;constitute a good reservoir - seal combination;the other is the existence of internal weathering crust composition of C2h,weathering crust in the freshwater dissolution porosity and organic acid - soluble pore as a reservoir,the upper dense volcanic rocks for cover.The model have the vital significance for seeking the volcanic rock crust of Weathering reservoir to the next step in Santanghu basin.