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If reservoir structure is non-flat then initial Reservoir Pressure at formation top will be varying across the field while the the Datum Pressure will be constant across the field.
This particularly helpful in Reservoir Pressure analysis during production so that areal Reservoir Pressure distribution recalculated to Datum shows only those pressure variations across the field which are related to production and not to the field structure.
The mathematical model of Datum Pressure is explained in Datum Pressure @model.
See Also
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Petroleum Industry / Upstream / Petroleum Engineering / Subsurface E&P Disciplines / Reservoir Engineering / Reservoir pressure
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