Changes

In a water drive reservoir, the oil zone is in communication with an aquifer that provides the bulk of the reservoir's drive energy. As oil is produced, the water in the aquifer expands and moves into the reservoir, displacing oil. Depending on the aquifer's strength, additional energy may be provided by solution gas expansion. Much less significant contributions are provided by the expansion of the reservoir rock and its associated water.

In a water drive reservoir, the oil zone is in communication with an aquifer that provides the bulk of the reservoir's drive energy. As oil is produced, the water in the aquifer expands and moves into the reservoir, displacing oil. Depending on the aquifer's strength, additional energy may be provided by solution gas expansion. Much less significant contributions are provided by the expansion of the reservoir rock and its associated water.

The geometry of the aquifer determines whether it is a ''bottom water'' or an ''edge water'' drive ([[:file:drive-mechanisms-and-recovery_fig5.png|Figure 5]]). In a bottom water drive, the aquifer is present below the entire reservoir and water influx moves vertically upward into the oil zone. In an edge water drive, the aquifer is located on the flanks of the reservoir and the water moves upward along the reservoir dip.

The geometry of the aquifer determines whether it is a ''bottom water'' or an ''edge water'' drive ([[:file:drive-mechanisms-and-recovery_fig5.png|Figure 5]]). In a bottom water drive, the aquifer is present below the entire reservoir and water influx moves vertically upward into the oil zone. In an edge water drive, the aquifer is located on the flanks of the reservoir and the water moves upward along the reservoir [[dip]].

[[file:drive-mechanisms-and-recovery_fig5.png|thumb|300px|{{figure_number|5}}Edge water versus bottom water drive reservoirs.]]

[[file:drive-mechanisms-and-recovery_fig5.png|thumb|300px|{{figure_number|5}}Edge water versus bottom water drive reservoirs.]]