松辽盆地兴城地区营城组火山岩储层次生矿物特征及其对储层物性的影响

Secondary Mineral Characteristic of Volcanic Reservoir in Yingcheng Formation of Xingcheng Area,Songliao Basin and its Impact on the Reservoir Properties

对松辽盆地兴城地区白垩系营城组火山岩岩石学研究结果表明,火山岩岩石类型主要为流纹岩和流纹质凝灰岩,少量英安岩、安山岩。本文从储层中次生矿物变化特征角度对火山岩储层进行了详细研究,结果表明,流纹岩中典型的次生矿物组合为绿泥石、石英、菱铁矿,其它少量和微量的次生矿物还包括云母、高岭石、玉髓、钠铁闪石、粘土矿物、绿帘石、沸石、萤石、黄铁矿等。本文按岩石类型以及次生矿物类型对储层进行了分类和对比研究,并阐述了次生矿物在时间上的变化特征和对储层发育的影响。研究区火山岩地层经历了强烈的溶蚀作用和胶结作用,溶蚀作用使储层产生粒间溶孔、溶缝和溶蚀填隙物内孔隙等次生孔隙,从而增大了储集空间;次生矿物对岩石的胶结作用大大降低了岩石的孔渗性能。有机质在成熟过程中释放的有机酸以及粘土矿物转化过程中产生的酸性地层水介质是产生大量次生孔隙的主要原因。

Through the research on the lithology of volcanic rock of Yingcheng formation of Cretaceous system in Songliao basin,it indicated that the main volcanic rock type are rhyolite and volcanic tuff,a little quartz andesite and andesite.In this thesis,it studies on the volcanic rock reservoir from the view of secondary mineral,which indicates that the typical secondary mineral assemblage of rhyolite are chlorite,quartz,siderite,except that,there are little glimmer,kaolinite,chalcedony,arfvedsonite,clay mineral,epidote,zeolite,fluorite and pyrite.The category and correlation study of the reservoir have been done from the rock type and secondary type,besides,the variation of the secondary with time and the effect on the reservoir also have been studied.The volcanic layer in the region of interest experienced very strongly dissolution and cementation.Dissolution created intergranular,dissolved fracture and inner pore of interstitial material,thereby,widening the reservoir space;cementation strengthened along with much secondary mineral generated which reduced rock's porosity and permeability.The organic acid that the organism released in the process of its maturation and impact of conversation of clay mineral,making the acid formation water which generated abundant secondary porosity in the volcanic reservoir.