不整合类型及其油气地质意义

Unconformity Type and Its Significance in Petroleum Geology

不整合类型多种多样,针对不整合的形态及形成机制将其分成7种类型:平行不整合、削截不整合、超覆不整合、褶皱不整合、断褶不整合、伸展不整合和生长不整合。不整合附近的岩层在纵向上呈层分布:从下至上依次为半风化岩石、风化粘土层和底砾岩。不整合在油气的运聚成藏过程中扮演重要角色:不整合面可以作为油气长距离运移的通道,古风化壳或古岩溶带能够改善岩层的储集性能,形成不整合油气藏。不整合的负面作用为:对盖层的破坏和烃源岩成熟度的影响。

Various unconformities can be classified into such seven types of unconformities by conformation and mechanism as parallel, truncation, overlap, fold, faulted-fold, extensional and growth ones. Vertically, rocks near the unconformity appear layers which are in turn semi-weathering rock, weathering clay bed and basal conglomerate. The unconformity plays important roles on the migration and accumulation of hydrocarbons in nature as a pathway for long-distance petroleum migration. And paleo-weathering crust or palaeokarst belt take the part of improvement of reservoir quality of rocks, forming unconformity reservoirs. However, the unconformity may cause caprock damage and affect the maturity of hydrocarbon source rocks.