Hydraulic Fracturing Wastewater Facility, OK

Project background and challenges

The reuse of produced water is becoming pivotal to the continued application of fracturing hydrocarbon recovery techniques. Sourcing suitable water and the high cost to chemically treat produced water are two reasons why the industry is seeking more economical and environmental sound surface water management solutions. Increased reuse of produced water conserves limited fresh water resources, reduces handling and hauling costs, and drastically reduces the volume of water injected underground for disposal.

Problems Unique to Produced Water:

• Mitigating the health and safety issues of stored water,
• Ensuring downstream chemical treatment effectiveness,
• Providing biological treatment and operational performance under highly variable flow and pit operating water level conditions.
• High salinity and dissolved solids concentrations in produced water severely challenge traditional aeration techniques.

While the sector’s economic and market conditions remain soft, an innovative, cost effective solution is being demonstrated at one Southern Oklahoma facility providing surface water management for the surrounding area and has a nominal throughput capacity of 10,000 billion barrels (bbls) per day.

The EDI Answer

The key process units at the facility include enhanced oil recovery and solids separation, aerated biological treatment for management of dissolved constituents and water quality, and storage for future fracturing activities. While the use of biological treatment is wide-spread throughout the wastewater treatment industry, its use is just emerging in the oil field sector. With proper design and equipment selection and sizing, robust, cost effective solutions are being installed and are helping operators remain competitive in a tight oil and gas market.

The solution for this site included:

• Ballasted, floor-mounted configuration for full pit drawdown capacity
• Modular construction for faster installation and re-deployment capabilities
• Deep (20-foot) operating depth for reduced land use
• Front to back maintenance service for high uptime performance
• Variable output blowers for operational flexibility and hands-off operation
• Thermally resistant materials for high temperature conditions
• Chemically-compatible, flexible membrane, fine pore diffusers for high operating efficiency and long service life.

Successful biological treatment requires a broad understanding of the operational objectives for the facility. Unlike conventional designs which focus on capacity and regulatory effluent standards, produced water treatment is akin to a manufacturing operation that needs to respond to the dynamic needs of the business. This includes but is not limited to mitigating the health and safety issues of stored water, ensuring downstream chemical treatment effectiveness, and providing treatment and operational performance under highly variable flow and operating water level conditions.

Aerobic biological treatment is energy intensive and aeration is the single largest requirement in the entire plant. To deliver best total ownership cost, a range of aeration solutions were evaluated. For this application, a high efficiency, variable output solution was selected and applied.

Operational flexibility was a key criterion since effective biologic treatment requires the paced supply of oxygen on a 1:1 ratio to Chemical Oxygen Demand reduction. In conceptual terms, 1bbl of produced water contains 1lb of COD, which requires 1lb of oxygen to remove.

The characteristics of produced water including high variability and elevated salinity represent a unique set of challenges. The materials of construction and operating range were reviewed in detail to provide the desired level of operational flexibility.

Upgraded System Performance:

System commissioning was completed in February 2017. The system has provided continuous treatment with no system major outages since commissioning. Energy use was reduced by over 50% as compared to alternate aeration solutions.

The capital and O&M costs for the aeration system amounts to a few cents per barrel of water treated making the solution attractive on both short and long-term project profiles.

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