SIGNIFICANCE OF OIL SHALE IN THE EOGENE PETROLEUM RESOURCE EVALUATION OF THE JIYANG DEPRESSION, THE BOHAIWAN BASIN

It was found in recent years that the formation of hundred million ton scale of oilfields was related to the oil shale of the lower sub-member of the 3rd member of the Shahejie Formation (for short Es³)in the Jiyang Depression on the bases of the detailed correlation of oil and gas to source rocks, and the important contribution of oil shale to hydrocarbons was understood again. There is a great amount of oil shale containing Botryococcus braunii and Coccolithophorida these algae-enriched layers of great hydrocarbon potential in the upper sub-member of Es⁴ and Es³ of the Jiyang Depression, it is an important contributor to hydrocarbons. Lateral migration was the important mode of primary hydrocarbon migration in oil shale. The existence of book structure, especially when oil shale cut by faults, was probably the main cause of the great enhancement of hydrocarbon discharge efficiency. Oil shale was separately basin-modelled and calculated in the Eogene petroleum resource evaluation of the Jiyang Depression, and its total amount resources was 13.8×10⁸t.