Sewer Water: An Alternate Water Source for a CO2 EOR Project

Water is utilized in oil field operations to increase oil recovery by conventional water flood and is increasingly being used in enhanced oil recovery (EOR) technology. In many areas there is not a sufficient supply of water form subsurface salt water formations. Shallow fresh water sands have been used in the past as an alternative source when the fresh water was compatible with the reservoir water and formation. Use of the fresh water is not practical in many areas. An extreme strain has been placed on the limited fresh water supply by its use for the general population and agricultural irrigation. Effluent from municipal sewer plants can be used as an alternate source of water for the oil field. Sewer water is being utilized successfully as the water source for the water injection requirements in the Hansford Marmaton CO2 EOR project. The source of water for the project is a portion of the 10,000 barrels of water per day available from the effluent of the water treatment plant in the small city of Spearman, Texas, population 3,800. Prior to injection, the water must be deoxidized, bacteria must be killed, and the suspended oil and grease must be removed. This paper reviews how these processes are being accomplished for the Hansford Marmaton Project. Additionally the problems encountered in installing the system, how they were resolved, the cost to implement and operate the water injection system are reviewed.