辽河断陷盆地火山岩储层岩石学及地球化学特征

Petrology and geochemistry characteristics of volcanic reservoirs in Liaohe basin

辽河断陷盆地火山岩类型有熔岩:粗面岩、粗安岩、安山玄武岩、安山岩、粗玄岩、玄武岩;火山碎屑岩:火山角砾岩、凝灰岩;次火山岩:粗面斑岩、辉绿岩。火山岩储层的储集空间类型有原生的气孔、杏仁体内孔、砾间孔、晶间孔、晶内缝、收缩缝等;次生的各种构造裂缝、砾间溶孔、砾内溶孔、晶间溶孔、晶内溶孔、杏仁体内溶孔和溶蚀缝。岩石类型、火山岩岩相是决定储层性质的内在因素,溶蚀作用、构造破裂作用和充填作用是影响储层发育的主要外部条件。火山岩为碱性-钙碱性中-基性岩,形成于大陆环境,属于板块内稳定构造区和岛弧及活动大陆边缘二者的派生产物。原始岩浆来源于上地幔,但在上侵过程中不同程度地混入地壳物质。

Volcanics in Liaohe basin include lava: trachyte, trachyandesite, andesitic basalt, andesite, trachybasalt, and basalt; volcanoclastic rock; volcanic breccia and eruptive tuff; subvolcanic rock; trachyporphyry and diabase. Reservoir space of volcanics include primary vesicle, amygdaloid inner pore, intergranular pore, intercrystal pore, in-tracrystalline fissure, and constricted fissure, etc. ; various secondary structural fracture, intergranular dissolved pore, intragranular dissolved pore, intercrystalline dissolved pore, intracrystalline dissolved pore, intra amygdaloid dissolved pore and solutional fracture. Rock types and volcanic lithofacies are internal factors determining reservoir nature, while dissolution, tectonic disruption and packing action are major external factors affecting reservoir growth. Volcanics here belong to alkalic-calc-alkalic neutral-basic rock, generated in continental environment, lie in stable structure zone within the plate, and are induced products of island arc and movable continental margin. Original magma came from outer mantle, but mixed with crustal substances to different extent during upward intrusion.