Physical Experiment Of Shallow Strata Hydrocarbon Enrichment Mechanism In Slope Zone Of Bohai Sea

In view of the difficulty of exploration and high probability of failure in the slope zone of Bohai Sea,this thesis extracts the key factors affecting hydrocarbon enrichment in the slope belt of Bohai Sea based on the meticulous anatomizing of successful and failed structures in the slope belt of Bozhong Sag,then uses the improved Hele-Shaw model to experiment the hydrocarbon migration process in the slope zone.The experimental results show that:（1）The smaller the slope zone dip angle is,the more oil accumulated in the slope zone;（2）The closer to the uplift,the greater the enrichment in the slope zone;（3）When the source rocks continue to expel hydrocarbons with high intensity,the vertical fault transport efficiency in the low part of the slope zone is high,and the shallow strata hydrocarbon accumulation is large;（4）When the presence of low permeability zone caused by unconformity lateral heterogeneity,the shallow strata hydrocarbon enrichment in the slope zone can also be increased.After hydrocarbon migration reached to N₁g and Nm through vertical fault,the influence of flower structure on hydrocarbon accumulation was experimented.The results show that without the control of catchment ridge,flower structure boundary fault is the main transport channel,and hydrocarbon is preferred to accumulate in one petal.Under the influence of catchment ridge,multiple faults of flower structure participate in transport simultaneously,and hydrocarbon accumulates at both flower center and petal.Based on the knowledge of physical experiment and the actual cases analysis,it is considered that the small slope zone dip angle is the main reason of shallow strata hydrocarbon enrichment in PL13-2 oilfield.However,the large slope zone dip angle is the main reason for the failure of QHD32-7 structure.The main reason of shallow strata hydrocarbon enrichment in Block 4 of Penglai 19-3 oilfield is that the main vertical transport fault is close to the uplift.In general,when certain conditions are met,hydrocarbon can accumulate in shallow strata of the slope zone in Bohai Sea,but the scale of hydrocarbon reservoirs is relatively small.