辽河东部凹陷北部不整合类型及油气成藏规律

Unconformity types and the relationship of unconformity and hydrocabon accumulation

不整合对油气藏形成有重要作用。辽河坳陷东部凹陷北部地区不整合较发育 ,根据实际资料研究沙三段顶面不整合类型 (削截、平行和超覆 )和不整合面上下 6类岩性接触关系的平面分布。不整合类型和不整合面上下岩性接触关系不同 ,对油气藏形成的作用不同 :下泥上砂的削截和平行不整合可在不整合面之上成藏 ;下砂上泥的削截不整合易在不整合面之下形成不整合遮挡油气藏 ;地层超覆不整合可形成地层超覆油气藏 ;不整合面上下均为砂岩 ,可作为沙三段烃源岩生成油气的运移通道 ;不整合面上下均为泥岩 ,可起封堵和区域盖层的作用。根据上泥下砂的不整合面分布区有利于形成不整合遮挡油气藏的认识 ,预测青龙台构造高部位和茨榆坨潜山的低带是有利目标区。图 5参

Unconformity plays an important role in hydrocarbon accumulation. Various unconformities are widely occurred in Dongbu sag, Liaohe depression. The regional distribution of unconformity and the lithological change upon unconformity surface are studied by the analysis of numerous data. It reveals that different unconformity types and different lithological changes upon unconformity surface impact differently on hydrocarbon accumulation. Hydrocarbons can be accumulated on the type Ⅰ 1 and Ⅰ 2 unconformities with mudstone below and sandstone upon. Unconformity reservoir can be formed under the type Ⅳ 1 truncation unconformity with sandstone below and mudstone upon. Stratigraphic onlap reservoir can be formed in the onlap unconformity stratiraphies. Type Ⅱunconformity with sandstone below and upon is favorable pathway for hydrocarbon migration. Type Ⅴunconformity with mudstone below and upon can be served as regional seal bed in hydrocarbon accumulation.