Tectonic Evolution Of Yannan Buried-hill Zone In Liaohe Beach Area And Hydrocarbon Accumulation

Yannan buried-hill zone located in the eastern edge of the eastern sag in Liaohe Beach Area, is a favorable petroleum zone, and Tan-Lu fault in eastern China go through here. Early extension of basin and late strike-slip of the Tan-Lu fault zone make tectonic evolution of Yannan buried-hill zone extremely complex. That the analysis of structural characteristic and tectonic evolution of Yannan buried-hill zone as the emphasis,and the investigation of structural controlling action on hydrocarbon accumulation plays a key role in hydrocarbon exploration.Structural characteristic of Yannan buried-hill zone is very complex. Four types of faults are developed, including early extensional faults, middle strike-slip extensional faults, late strike-slip faults and long-term active faults. Three groups of faults that main faults in NE direction, the en echelon strike-slip extension faults in EW direction and thrust faults induced by strike-slip deformation in SN direction compose of the unified fault system. Four types of structure styles are developed, including extensional, strike-slip, compression and inversion structural styles.Yannan buried-hill zone is the result of strike-slip of the Tan-Lu fault zone in the process of rift basin. The tectonic framework is characterized by“east-west zonation and south-north subsection”. Yannan buried-hill zone went through four basin forming stages based on pre-Tertiary, including the intensive rift stage,the fault depression stage,another strike-slip extension rift stage and the depression stage, And two strike-slip reformation stages related to the Tan-Lu fault, including Late Dongying period and Late Pliocene to Quaternary. Tectonic evolution of Yannan buried-hill zone overall performanced of early extension, middle strike-slip extension and late strike-slip transform.Tectonic activities of Yannan buried-hill have important controlling action on hydrocarbon accumulation. Episodic tectonic activities controll the development of source-reservoir- caprock assemblages,the faults provide access for hydrocarbon migration, various structural styles provide favorable structural traps, the banded deformation controll distribution of hydrocarbon in the plane. That the main structural deformation stages match hydrocarbon accumulation stages well is conducive to hydrocarbon accumulation. And its favorable area are evaluated in this paper. Buried-hill drape structure, nose structure sheltered by Yannan fault and thrust faults and graben antiform structure in central uplift are favorable exploration direction.