塔里木盆地下古生界白云岩储层类型及特征

Types and the Characteristics of Lower Paleozoic Dolostone Reservoirs in Tarim Basin

根据60口井岩心及薄片的观察,塔里木盆地寒武系—奥陶系白云岩储层可划分为五种类型。萨布哈白云岩储层发育于潮间—潮上坪蒸发环境,以泥晶白云岩为特征,孔隙类型有膏溶孔及白云岩砾间孔。渗透回流白云岩储层发育于潟湖蒸发环境,以礁滩体组构选择性白云石化为特征,孔隙类型有铸模孔、膏溶孔、残留粒间孔。埋藏白云岩储层以白云石交代灰质或白云石重结晶形成的结晶白云岩为特征,孔隙类型有晶间孔及晶间溶孔。热液白云岩储层以受热液改造的结晶白云岩为特征,往往与热液矿物伴生,受断层、不整合面等热液通道控制。构造裂缝型白云岩储层储集空间除裂缝外,常见沿裂缝发育的溶孔。不同类型白云岩储层的主控因素和分布规律各不相同。

Based on the observations of thin sections and cores from 60 wells,five types of dolostone reservoirs can be recognized from the Cambrian-Ordovician carbonate rocks in Tarim basin. Sabkha dolostone reservoirs developed in intertidal to supratidal flat environment with gypsum-dissolved porespace and collapsed interbreccia porespace scattered in fine dolostone,Seepage reflux dolostone reservoirs that are characterized by fabric selective dolomitization developed in evaporite lagoon environment with moldic,gypsum-dissolved and intergrain porespace. Subsurface dolostone reservoirs that are characterized by replacement of limestone and recrystallization of fine dolomite developed in burial environment with intercrystalline porespace. The development of hydrothermal dolostone reservoirs that are characterized of coarse dolomite and accompanying hydrothermal mineral are controlled by faults and unconformity. Fractures are common in delostone which is composed of fractured dolostone reservoirs. Different types of dolostone reservoirs have their own different origin and distribution.