by TexasEx2006 » Fri 23 Mar 2007, 17:08:20
Waterflood is a proven old technology that has been around for decades. It is completely unrelated to well depth and drilling.
Water injection or waterflood is a method of oil, gas, & condensate recovery in which water is injected into the reservoir formation to displace residual oil and maintain well pressures. The water from injection wells physically sweeps the displaced oil to adjacent production wells.
It is always preferred to used produced water (water that comes out of the field with the oil in production) as your flooding media. By doing so you avoid issues regarding reservoir compatibility, etc. However, as the field ages more water is required to maintain reservoir pressures. Seawater is often used to do this.
Typically the seawater is filtered for large particulate, algae, shell's, etc. Upon initial filtration, the seawater is deaerated, more specifically deoxygenated. Removing the oxygen helps prevent corrosion problems in the injection pipeline. There are reasons why this occurs, bacteria, etc., but I doubt you require the details. After being pipelined to the injection manifold, the water is typically filtered once more time to prevent damage to the reservoir formation. What you want to avoid is plugging the formation with particulate, sand, corrosion, etc., which can reduce the ability to inject and maintain well pressures, sweep efficiencies, etc.
Hope this helps. Like I said, this practice has been around for quite some time. It is proven.