Hydrodynamic conditions in subaerial regions

When all or part of the sedimentary basin is above sea level, or when the basin is surrounded by areas of high topographic relief, the influence of gravity-induced groundwater flow on hydrocarbon migration should be evaluated. 

Areas of high topographic relief can be identified from topographic maps of the ground surface and from images produced by remote sensing techniques. 

The minimal depth of occurrence of active flow of groundwater in the regional recharge area can be inferred from the maximum depth of occurrence of negative temperature anomalies or relative low geothermal gradients or heat 

After the probable depth of penetration of the regional gravity-induced groundwater flow system has been identified, it should be decided whether or not the gravity-induced flow system should be taken into accoimt in the further evaluation of the potential paths of hydrocarbon migration. 

The identification of the general regional pattern of groundwater flow will only be useful for those parts of the sedimentary basin or adjacent areas, where the depth of penetration of the flow system has been foimd to be deep enough to be of potential influence on hydrocarbon migration. 

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