二叠系碎屑岩储集层是准噶尔盆地西北缘地区重要的勘探层位,埋藏深度大,研究其次生孔隙分布及其控制因素是研究区储集层研究的一项难点.利用岩芯、铸体薄片、荧光薄片、扫描电镜、黏土矿物等资料,结合沉积相、构造演化及有机质演化特征,对二叠系碎屑岩次生孔隙发育控制因素进行了研究.研究结果表明:二叠系碎屑岩除发育原生粒间孔外,还发育颗粒溶孔、胶结物溶孔及裂缝等次生孔隙.颗粒溶孔、碳酸盐及沸石胶结物溶孔主要受烃源岩热演化产生的有机酸及大气淡水无机酸作用的范围、规模控制.无机酸成因的溶孔主要发育于不整合面和断裂发育的盆地边缘区域,有机酸成因的次生孔主要发育于紧临烃源岩的盆地中部区域;裂缝主要是在构造挤压应力作用下产生,受构造应力大小、岩性粒级及杂基含量控制,主要分布于西北缘逆冲断裂带内低杂基含量的砂砾岩中.平面分布上,西北缘二叠系碎屑岩储集空间类型在盆地边缘以原生粒间孔为主、其次为无机酸成因的溶蚀孔及裂缝;向盆地中部过渡为有机成因的溶孔为主,原生粒间孔次之的储集空间组合.结合研究区沉积相展布、胶结物分布、构造特征及有机质演化特征,指出盆地中部的扇三角洲前缘区带,浊沸石胶结物发育,靠近烃源岩,处于三期有机酸运移的上倾方向,是有利的浊沸石溶蚀孔隙发育区带.%Permian clastic reservoir is an important exploration horizon in the northwest margin of Junggar Basin,with the burial depth more than 3 600 meters.And it is very important to study Permian clastic reservoir secondary pore developement and its controlling factors.Based on the thin section analysis of 1 400 pieces in more than 120 wells,core observation,fluorescent thin-section,scanning electron microscopy,clay mineral,and in combination with sedimentary facies,tectonic evolution and organic evolution characteristics,Permian clastic reservoir secondary porosity developed law and controlling factors are studied.Casting thin section show that Permian clastic reservoir has development not only primary intergranular pore,but also grain dissolved pore,cement dissolution pore and fracture of secondary porosity.It is concluded that primary intergranular pore is mainly controlled by sedimentary facies belt,compaction and cementation.The primary intergranular pore developed in coarse,well-sorted,high maturity of structure and composition.The corresponding microfacies are braided channel of fan delta plain and underwater channel of fan delta front.The primary intergranular pore are developed in basin edge,and decreased to basin center.The dissolved pore of grains,carbonate cements and zeolite cements are controlled by the scale and scope of inorganic acid and organic acids.The inorganic acid dissolution pore is developed regionally in basin edge where the unconformity surface and faults are developed.The organic acid dissolution pore is developed in near hydrocarbon of source rock,mainly distributed in basin center.Fractures are generated under the action of tectonic compression,and it is controlled by tectonic stress strength,grade size and matrix content.Fractures are mainly distributed in low matrix content sandy conglomerate in fault zone of northwest margin.Horizontally in the basin edge,the mainly Permian reservoir pore type is primary intergranular pore,followed by the inorganic acid dissolution pore and fracture.In basin center,the major pore type is organic acid dissolution pore,secondly is primary intergranular pore.Integrating with distribution characteristics of sedimentary facies and zeolite cements,structural feature and the evolution history of organic matter,it is considered that middle-belt of basin is the favorable zone to form lawnontite dissolution pore because it is the fan delta front sub-facies and laumontite cement development area,meanwhile it is near hydrocarbon source rocks and located in the updip direction of three periods organic acid migration.It points out that central basin is laumonite dissolution pore development area,and it's the favorable Permian clastic reservoir for Permian petroleum exploration.
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