塔中地区深部流体对碳酸盐岩储层的改造作用

塔中地区岩石及原油的稀土元素分析、二氧化碳碳同位素分析以及储层流体包裹体测温证实了深部流体的存在。盆地基底以下的深部流体通过深大断裂及火山活动进入盆地内,通过物质和能量交换对碳酸盐岩储层进行溶蚀和交代,使碳酸盐岩储集层的孔、渗结构发生改变,从而形成深埋改造型的优质碳酸盐岩储层。塔中西部地区沿大断裂及火山活动区发现的萤石矿带是深部流体作用的产物,是塔中45油田的主要储集层类型。深部流体的来源及活动范围与深大断裂以及火山活动密切相关,深大断裂以及火山岩发育区可以作为寻找深部流体改造型储层的标志。

Carbonate reservoirs transformed by deep fluid in Tazhong area

Occurrence of deep fluids in Tazhong area has been confirmed through analyzing rare-earth elements in rock and oil samples,carbon isotope of carbon dioxide and fluid inclusion thermometry in reservoir rocks.The deep fluids below the basement entered the basin along the discordogenic faults and through volcanic activity,and the carbonate reservoirs were modified by dissolution and metasomatosis through material and energy exchanges.The porosity and permeability of the carbonate reservoirs were thus improved,leading to the formation of deeply buried and modified type good carbonate reservoirs.The fluorspar ore belts,discovered along the large fault and in volcanic activity area in the western part of Tazhong,are the result of activities of deep fluids,and they are the main reservoir types in Tazhong 45 oilfield.The origin and sphere of activity of deep fluids are closely related to discordogenic faults and vol- canic activities.Areas with well-developed discordogenic faults and volcanic rocks can be considered as indicators for seeking deep fluid modified reservoirs.