滨里海盆地东南缘晚古生代碳酸盐岩台地特征及控制因素

Characteristics and Controlling Factors of Late Paleozoic Carbonate Platform in the Southeast Part of Precaspian Basin

滨里海盆地东南缘晚古生代广泛发育碳酸盐岩台地,生物礁发育,为油气聚集提供了良好的储层。受北乌斯丘尔特板块和乌拉尔造山运动的影响,南恩巴和扎纳诺尔碳酸盐岩台地具有3层结构,田吉兹-卡沙甘台地和特梅尔台地具有2层结构;依据沉积特征、沉积演化及井震资料等建立了各碳酸盐岩台地的沉积模式。各碳酸盐岩台地发育以孔隙为主的储层,亦有溶洞和裂缝,是沉积作用及后期白云岩化、淋滤、重结晶等共同作用的结果。研究表明,各碳酸盐岩台地生长发育过程中主要受相对海平面变化的影响,构造运动控制着碳酸盐岩台地的位置、形态、沉积相带分布及地层结构,水动力条件强弱决定了沉积物的类型。碳酸盐岩台地的不同特征对油气勘探目标评价具有指导意义。

Carbonate platform sediments and bioherms which were widely developed in the southeast part of Precaspian Basin provide good reservoir for oil and gas accumulation.Affected by the North Ustyurt Plate and Ural Orogeny,Nan Enba and Zana Noel Platform has three-layer structure,and Tengiz-Kashagan and Termel platform have two-layer structure.Based on sedimentary characteristics,sedimentary evolution and well-seismic data,different carbonate platform depositional model are established.Reservoir in various platform generally develops pore,hole and fracture,which is the result of jointly controlled by later dolomitization,eluvial and recrystallization.Study on the controlling factors demonstrate that platform development is mainly affected by the relative sea-level change,tectonic movement controls the location of carbonate platforms,their form,distribution of sedimentary facies and stratigraphic structure,and hydrodynamic conditions determines the type of sediments.Different features of carbonate platform are important for guiding the evaluation of oil and gas exploration target.