The Structure Types And Hydrocarbon Accumulation Features In The West Of Liaohe Offshore Area

The western region of Liaohe offshore formed in Mesozoic-Cenozoic is continental rift basin, of which Cenozoic tectonic evolution experienced two major extensional phase including rift and depression stage. Recognizing structural characteristics will contribute to analyze the trap and reservoir from the actual exploration in the western region.The structure types can be classified to block, anticline and structural transfer zone through deep study of structural characteristics in this area. According to the Sequence in the form and arrangement of the block, it can be divided into co-rotating block, reverse block, graben, horst and the "wedge" block. The anticline caused by fault activity includes drag anticline, reverse drag anticline and gravity slump anticline, and also includes drape anticline because of different compaction on the hill. Structural transfer zone develops in a relatively high position. mainly affected by basement patterns and fault activity. It can be categorized to transverse uplift, trend slope, oblique anticline and horst according to their morphological characteristics. Indeed, each category has its own development degree and distribution feature.By researching on hydrocarbon accumulation conditions confirms that the study area mainly developed Es3 effective source rock which generated in Hainan sag and also formed two combinations of reservoir and seal:Paleogene clastic and buried hill combinations of reservoir and seal. Through the study of organic inclusions and basin burial history shows that oil and gas migrate in late Dongying and Guantao stages and hydrocarbon migrate in the major channel for the fault, unconformity and connected sand bodies.Hydrocarbon reservoirs, Based on trap morphology, are divided into fault nose, block, faulted anticline and drape anticline in study area. Though in-depth analysis of the structure types and hydrocarbon accumulation conditions of typical oil reservoirs, summarized the various types of reservoir characteristics and hydrocarbon accumulation distribution. Block reservoir mainly distributed along the fault zone, but smaller; fault nose mainly along the slope-based transformation, and larger; faulted anticline and drape anticline reservoir mainly along with the extensional anticline zone.