In drilling, "Water Flood" is a method of secondary oil recovery in which water is injected into
the reservoir formation to displace residual oil. The water from injection wells
physically sweeps the displaced oil to adjacent production wells. Potential
problems associated with water flood techniques include inefficient recovery due
to variable permeability, or similar conditions affecting fluid transport within
the reservoir, and early water breakthrough that may cause production and
surface processing problems.
The water injection method used in
oil production is where water is injected back into the reservoir usually to
increase pressure and thereby stimulate production. Water injection wells can be
found both on- and offshore. This method is used to increase oil recovery from
an existing reservoir.
Water is injected into the well for two reasons:
For pressure support of the reservoir
(also known as voidage replacement).
To sweep or displace the oil from the
reservoir, and push it towards an oil production well.
Normally only 30% of the oil in a reservoir can be extracted, but water
injection increases that percentage (known as the recovery factor) and maintains
the production rate of a reservoir over a longer period of time.