Distribution law and influencing factors of oil column height in lithologic reservoirs in lower member of Minghuazhen Formation in Bohai Sea
The characteristics and reserve scale of lithologic reservoirs in the lower member of Minghuazhen Formation in the Bohai Sea are quite different.As a key parameter of reservoir evaluation,the height of oil columns directly affects the reserve scale of reservoirs,but its distribution law and influencing factors are not clear.Based on the exploration and development data of about 460 lithologic reservoirs in the lower member of Minghuazhen Formation of Bohai Sea,the spatial distribution law of oil column height in shallow lithologic reservoirs in the lower member of Minghuazhen Formation was clarified by using statistical means and geochemical evidence on the basis of fully understanding the geological background.By further analyzing the relationship between oil column height and oil and gas charging intensity,regional cap layer distribution,trap type,fault-sand coupling degree,and other reservoir forming elements,the influencing factors of oil column height were clarified.The results show that:①Controlled by oil and gas charging intensity,the oil column height in lithologic reservoirs in the lower member of Minghuazhen Formation has the characteristics of small lifted areas and large depressed areas on the plane,and the average oil column height difference is about two times.②Controlled by the regional cap layer,the oil column height is small above the cap layer but large below the cap layer in the vertical direction.The average oil column height in the lower Ⅲ/Ⅳ oil group is about two times that in the Ⅰ/Ⅱ oil group.③Controlled by the location of oil and gas accumulation and the preservation ability of side sealing,the height of oil columns in the faulted side sealing reservoir is generally higher than that in the lithologic pinch-out reservoir,and the average oil column height difference is about 2.5 times.④Affected by the fault-sand coupling degree,the migration ability of oil and gas in the faulted uplifted area and the depressed area is quite different.In the uplifted area,the faults that cut through the oil and gas transport layer in the Guantao Formation area can play a migration role,while in the depressed area,only the faults that cut through the deep convergence ridge can serve as effective oil source faults.The distribution law and influencing factors of the oil column height in lithologic reservoirs in the lower member of Minghuazhen Formation in Bohai Sea provide a reference for the subsequent value exploration and fine exploration of lithologic reservoirs.
lithologic reservoiroil column heightlower member of Minghuazhen Formationdistribution lawBohai Sea
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