塔里木盆地古生界不同成因斜坡带特征与油气成藏组合

塔里木盆地古隆起和古斜坡控制油气富集已为勘探实践所证实。古生界广泛分布的斜坡带按其成因特点可分为3类:即地层形成期的沉积建造斜坡、构造变革改造期的侵蚀地貌斜坡和构造抬升翘倾作用形成的构造斜坡。不同类型的斜坡带发育了不同的油气成藏组合:沉积建造斜坡带发育了以礁滩体为主要储层、致密碳酸盐岩或上奥陶统泥岩为主要盖层的成藏组合;岩溶斜坡带发育了不同层系岩溶储层(中、下奥陶统岩溶储层、上奥陶统岩溶储层和寒武系白云岩储层)与不同层系泥岩盖层(上奥陶统泥岩盖层、志留系泥岩盖层和石炭系下泥岩段盖层)构成的成藏组合;地层超覆斜坡带在志留系和上泥盆统—石炭系形成了以地层超覆圈闭为主、构造-地层(或岩性)圈闭为辅、泥岩段为盖层的成藏组合。

The characteristics of Palaeozoic slopes with different geneses and oil/gas plays in the Tarim basin

It is proved by exploration that the petroleum accumulation is controlled by paleouplift and paleoslope in the Tarim basin.The slope regions distributed widely in the Paleozoic can be grouped into 3 types by their origin:the sedimentary assemblage slope formed in the bed formation stage,the erosional geomorphology slope formed in the tectonic disturbance stage,and the structural slope formed by tectonic uplift and tilt process.Each type developed different oil/gas play.The sedimentary assemblage slope developed the oil/gas play with reef flat as the main reservoir and dense carbonate or Upper Ordovician shale as the main cap rock.In the karst slope,the oil/gas play is composed of karst reservoir(Lower-Middle Ordovician karst reservoir,Upper Ordovician karst reservoir and Cambrian dolomite reservoir) and shale cap rock(Upper Ordovician shale,Silurian shale and Carboniferous lower shale section cap rock) of different ages.In the Silurian and the Upper Devonian-Carboniferous,the stratigraphic overlapping slope developed the oil/gas play mainly in the stratigraphic overlapping trap and secondarily in the structural-stratigraphic(or lithologic) trap,and the cap rock is the overlying shale section.