What is Produced Water?
Produced water is any water that is conveyed to the surface from an oil or gas reservoir during oil and gas production. This water will be from one or more of the following sources:
> Connate water which is present in the reservoir prior to production
> Condensed water which is condensed from the produced gas in the production tubing and topside equipment
> Injected water which is originated from the injection wells adjacent to producing well
Produced water composition
Physical and chemical properties of produced water vary depending on many factors including:
> Reservoir geology
> Hydrocarbon composition
> Geographical location
> Water injection history
The chemical composition of produced water will change during the production lifetime of a reservoir. Most production wells produce dry oil at the beginning of the field life. Produced water volumes increase slowly as connate water begins to contaminate the oil. The water cut increases at an accelerated rate once the water/oil interface reaches the wells, this being known as “water breakthrough”. Composition of the produced water will reflect an increase in the proportion of injected water. As oilfields age, water becomes the predominant fluid to be treated.