济阳坳陷第三系不整合油气藏运聚成藏模式

济阳坳陷第三系不整合油气藏平面上主要位于盆缘地层超剥带内的大型鼻状构造和凸起的翼部,纵向上主要分布在一级不整合面附近。根据不整合面上、下地层的风化程度及其保存状况,将第三系不整合体划分为3种结构类型:Ⅰ型、Ⅱ型和Ⅲ型。不同的结构类型具有不同的输导/遮挡能力。第三系不整合油气成藏的主控因素可概括为古地貌、输导体系和遮挡层。根据圈闭发育的构造位置、储层产状和油气运移的方向,建立了斜坡正向运聚和凸起侧向运聚两种不整合油气藏运聚成藏模式。两种成藏模式通常均可发育近源遮挡油气藏和远源超覆油气藏,不整合体结构中的"渗透天窗"是两类油气藏的转折点。

Hydrocarbon migration and accumulation patterns in the Tertiary unconformity reservoirs of the Jiyang depression

Laterally,the Tertiary unconformity reservoirs of the Jiyang depression are mainly distributed in the large nosing structures of the marginal overlap zones and the flanks of salients,while vertically,they occur mainly near the first-order unconformity surface.Three types of structures,namely the type Ⅰ,Ⅱ,and Ⅲ,are identified in the Tertiary unconformity surface according to the degree of weathering and preservation of strata both above and below the surface.Different types of structures vary in conductivity/sealing ability.The main factors that control hydrocarbon accumulation in the Tertiary unconformity reservoirs are palaeogeomorphology,conducting systems and barrier beds.Two patterns of hydrocarbon migration and accumulation,namely forward direction pat-tern on slope and sideway pattern on salient,are established through observation of structural location of uncon-formity traps,occurrence of reservoirs,and migration direction of hydrocarbons.Both of the patterns are favorable for development of proximal sealed reservoirs and distal overlap reservoirs,with the"conducting hatch"in un-conformity body acting as the transition between these two kinds of reservoirs.