Unconformity types and the relationship of unconformity and hydrocabon accumulation

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.