Less Brine, More Benefits

Water management and treatment are critical operating issues for coal bed methane gas developers, like Marathon Oil Company, who seek a reliable process that consistently meets water quality discharge limits. Without a compliant operation, a portion of Marathon’s Sheridan, Wyoming gas field could not be effectively produced, affecting its bottom line and the local economy. Through design-build delivery, CDM Smith implemented a first-of-its-kind, innovative water treatment and reuse system that reliably and safely met all water discharge limits—protecting the environment and fresh water supplies, controlling treatment costs, and enabling Marathon Oil to focus on their core business of gas operations.

CDM Smith designed and constructed the first-of-its-kind green sand filtration, ion exchange and reverse osmosis (RO) water treatment process, capable of treating 35,000 barrels of produced water per day. The efficient and integrated process enabled a very high water recovery rate—more than 99 percent—and dramatically reduced the use of chemicals, such as sulfuric acid. The environmentally safe and cost-effective system reduced sodium and total dissolved solids, consistently producing effluent that surpassed all water discharge limits and could safely be discharged to a local stream or used for irrigation.

The facility represents holistic water management in the Powder River Basin, eliminating deep-well injection or direct discharge and extending water resources for local farmers. The facility is also the first RO membrane plant to cost-effectively treat produced water in the Powder River Basin. High silica content in the basin’s water consistently fouled previous membrane systems. The CDM Smith patent-pending treatment process uses a unique combination of four different membranes designed to minimize silica fouling.

While Marathon's previous treatment system required 22 truck trips per month to deliver hazardous chemicals, the new process requires little chemical addition and produces a small amount of brine that can be managed onsite. As a result, the number of trucks to the rural Wyoming site was reduced by 75 percent—greatly reducing operational costs, traffic volume, and the potential for accidents and hazardous material spills—major benefits for the client, landowner and farming community. Additionally, the entire project—a total of 17,000 man hours—was completed without a single safety incident, an accomplishment recognized by the National Safety Council with a valued Safety Performance Award.