Abstract:

Based on calculation of hydrocarbon generation and expulsion through TSM basin simulation,potential field analysis,and oil/gas migration channel modeling,dynamic and quantitative resources calculation methods are proposed for plays and structural zones in an attempt to determine the migrated and accumulated resources and pin down their locations,so as to realize dynamic assessment of resources.Zhentong depression in Subei basin is divided into four plays(fault terrace,inner slope,hinge belt,and outer slope) and 11 structural zones according to hydrocarbon expulsion potentials and structural features,and these methods are used to quantitatively calculate the total volume of oil and gas migrated and accumulated in the main targets across all the plays since the deposition of the Sanduo Formation(35.2Ma).The calculation indicates that the main period of hydrocarbon migration and accumulation is from the deposition of the Yancheng Formation(23.2Ma) till present.During this period,about 9.98Mt of hydrocarbons migrated from Sanduo Formation and accumulated in fault terrace play,accounting for 52.0% of the total hydrocarbons generated by this formation.While in the inner slope,the volume from the Dainan Formation is about 21.59 Mt(51.0% of the total),from the 3^rd member of Funin Formation is 145.19Mt(48.5% of its total).The absolute magnitudes of hydrocarbons migrated and accumulated in the fault terrace play are about 61.70 Mt from the 3^rd member of Funin,25.39 Mt from Taizhou Formation,and 19.70 Mt from the 1^st member of Funin Formation.Therefore,in respect of quantitive resource assessment,the exploration focus shall be put on the 3^rd member of Funing Formation and Sanduo Formation in the fault terrace play,while in the inner slope play,it shall be put on the Taizhou Formation,1^st and 3^rd members of Funin Formation,and Dainan Formation.

Key words: migration and accumulation path, quantitative assessment, play, hydrocarbon resources, Zhentong depression, Subei basin