The Hydrocarbon Accumulation Mechanism And Model Of Shanghe And Wuhaozhuang Oilfield In Jiyang Depression

The research object of this paper is Shanghe and Wuhaozhuang Oilfield in Jiyang Depression. Based on the analysis of the geological backgrounds of the hydrocarbon accumulation, the basic characteristics,the accumulation law and the reservoir formation mechanism are dissected and the models of hydrocarbon accumulation are created for the two oilfields.Through the study of fault throw,growth index and SGR,the fault activity and the sealing characteristics of the area are apparent ,moreover,the migratory direction and the pathway of oil-gas in Shanghe Oilfield are clarified through the studying of hydrocarbon which was left behind,the physical property of the crude oil ,etc. The faults dominated the vertical migration and accumulation of the hydrocarbon in Shanghe oilfield, three major sectional faults are the favorable vertical passageway of the oil and gas for their continuous movements in the Guantao depositional period. Meanwhile those faults which maintain good lateral sealing capacity can lead the hydrocarbon to accumulate easily. The condition of lateral sealing capacity is that the SGR number reaches to a limit at 0.75. The faults and sandstones constitute a ladder pathway system and the hydrocarbon migrates through them under the drive of its buoyancy from Shang 4 Block to Shang 1 Block.Based the measured data, the formation pressure in Wuhaozhuang area is analyzed. The abnormal pressure appears at the depth of 3100 m intially and then reaches to the top at the height of about 3500m.The low or normal pressure often occurs in the structural high location such as the fracture zone and the ramp region, while the high pressure occurs in the sag region. The abnormal high pressure area are rich in lithologic and structural-lithologic reservoirs, the hydrocarbon height here is great, the proved reserves are abundant and oil properties are good in these area while the normal or low pressure area is full of litho- structural, fault screened and unconformity reservoirs which is low in aspects such as hydrocarbon height and proved reserves.The accumulation law and main controlling factors of the hydrocarbon in the two oilfield are analyzed and compared to create the models of hydrocarbon accumulation respectively. There is a law with the oil and gas in Shanghe Oilfield that they are distributed ladder in many layers in vertical section and are distributed banded by faults in plane scale. The oil and gas accumulation style are mainly fault step forward, the mode of hydrocarbon migration and reservoir formation are main ladder . Faults, the matching relation of the faults and the sandstones as well as the cap rocks are the main factors which have an influence on the accumulation of hydrocarbon in this aera.The oil and gas in Wuhaozhuang Oilfield are distributed blocklike near the Source Rocks. The distribution range in vertical section decreased gradually from deep to shallow aera. They are located in Es3x of the east sub-sag which is characterized by its self generation and self containment . The self-generated and self-contained model of hydrocarbon migration and accumulation is mainly high pressure-self generated. The main controlling factors of hydrocarbon accumulation are the source rocks, the reservoir rocks and the driving force.