Robert P. Cathey
Cleaner burning natural gas recovered from unconventional shale plays is now considered to be the next step forward in the fossil-fuels recovery challenge and will help to increase domestic energy supply. The large volume and long-term potential of these plays are driving expanded exploration of this previously under-exploited resource. With this expanded exploration will come increased demand for clean, reusable water.
As many Oil & Gas Monitor readers are aware, hydraulic fracturing or “fracking” typically requires millions of gallons of water to be mixed with fine sand and chemicals that are injected at high pressure into the wellbore. Some of the chemicals used in this process are intended to treat the water for microbial control, scale inhibition, and friction reduction. Many oil and gas operators are turning towards alternative treatment methods, such as disinfection technologies, in order to reduce the use of chemicals.
Another recent trend is the reuse of water recovered from producing oil and gas wells. The flowback waters recovered in the first few weeks of production and the subsequent produced water recovered throughout the life cycle of the well contain increasingly higher levels of organic material and dissolved solids. Traditionally, this water would be disposed of using class II injection wells. However, recently the industry has begun to find ways to treat and reuse this water, which can reduce costs in some plays, preserve fresh water resources, and improve the sustainability of the hydraulic fracturing operation.
The factors driving these recent water management trends include:
- Handling and transportation of chemicals
- Road damage and impact on infrastructure
- Water sourcing and permitting issues
- Availability and cost of disposal
- Regulatory changes
- Stakeholder perception
Due to recent technological innovations in chemical-free water treatment, exploration and production (E&P) companies are taking action to address the economic, environmental and public pressures that are driving awareness of the urgent need for intelligent water conservation. In the case of hydraulic fracturing, water innovation is critical for ensuring the long-term success of the industry — and chemical-free wastewater treatment is a prime example of innovation that is enabling energy production with improved economic, environmental and social benefits.
The primary driver of innovation with respect to chemical-free water treatment in the fracturing process is improved economics for the operator. Effective water management can address operating costs that continue to increase such as water acquisition, water transportation, water disposal and chemical treatment costs.
Ecosphere Energy Services, LLC and its affiliates have commercialized an advanced oxidation process (AOP) invented by Ecosphere Technologies, Inc. This field-tested and proven approach to chemical-free wastewater treatment in the hydraulic fracturing process combines ozone, hydrodynamic cavitation, acoustic cavitation, and electro-chemical oxidation into one process to provide operators with microbial control and scale inhibition, while allowing the operator to reuse and recycle their flowback and produced waters. The systems are mobile and are capable of treating fluids onsite as water is being pumped down-hole. The newest AOP design from Ecosphere is a mobile unit that processes fluids at up to 80 barrels per minute (bpm). As flow rates change from site to site, multiple AOP systems are connected to meet the specific operators treatment requirements. In operation, since 2009, this AOP has been successfully used on over 570 oil and natural gas wells to replace chemical biocides and scale-inhibitors for operators in shale plays around the United States. As a result, approximately 2 billion gallons of water have been recycled.
The benefits of Advanced Oxidation are significant:
- Improves economics – versus chemical treatment for blended recycled and fresh water, as well as the trucking and disposal costs mitigated by recycling flowback and produced fluid
- Reduces the consumptive use of fresh water by allowing operators to recycle their wastewaters
- Leaves no secondary waste stream
- Eliminates chemicals from the treatment process
- Reduces the need for water disposal
- Reduces water acquisition costs
Other types of water treatment and recycling technologies are also being applied to the treatment of hydraulic fracturing wastewater. These include processes such as filtration, evaporation, chemical treatment, electro-coagulation and desalination. While certain technologies will work better than others depending on the naturally-occurring contamination present within specific geologies of the various shale plays, one thing is clear – the need for compatible and economical water treatment and recycling technologies will grow in lockstep with the growth of the exploration and production industry.
Through invention and application of technology, exploration and production companies will continue to improve their water conservation practices so they can meet their production goals and environmental requirements successfully, while also improving the economics of their operations and their relationships with the local communities in which they operate.