Kevin Juniel, NATCO Group
Produced water is the aqueous liquid phase that is co-produced from a producing well along with the oil and/or gas phases during normal production operations. Usually, the fluids that are removed from the reservoir by the producing well are brought to the surface and separated into an oil stream, a gas stream and a water stream. The main components of the water stream that is separated are: Water, Suspended oil, Dissolved oil, Suspended solids (scale, corrosion products, sand, etc.), Dissolved solids, Dissolved Gases (CO , H2S, O2 ), Bacteriological matter, & Added materials (treating chemicals, kill fluids, acids, etc.). It should be noted that, over the life of the well or field, the volume of water produced will exceed the volume of oil produced by a factor of 3-6 times. Unfortunately, at the present time, the produced water is not a saleable product of the operation. Hence, an operator is faced with a serious challenge of how to handle relatively large amounts of produced water at the lowest possible cost. In many land-based production operations, the produced water is either injected into a disposal well or the water is injected into a producing formation for enhanced oil recovery purposes via waterflood or steamflood operations. Before being injected for either disposal or enhanced recovery, the produced water must undergo treatment to render the water suitable for use. The purpose of this paper is to present a general, but practical, overview of the equipment and technology involved in water treating for a produced water injection project. This paper is not meant to present an exhaustive coverage of the material but to provide basic, general information with which an operator can become familiar with the primary decisions required to properly treat produced water for injection. To be covered are produced water treating objectives, produced water treating technology and equipment, and a thought process for the practical application of this equipment to land-based injection operations.