Emerging technologies for produced water challenges in oil and gas operations
Oil and gas produced water treatment is one of the fastest growing markets in the world. Most available freshwater does not meet current water demands that continue to grow at a rapid rate due to the booming oil and gas sector. Water needs vary from user to user and region to region, and optimal water solutions will also vary with different water types, but one thing is certain — new technological solutions are a must to address the issue of adequate freshwater supply.
Freshwater challenges in oil and gas operations
Freshwater is an essential commodity in oil and gas operations, such as for fracturing of a well. During a fracking operation, chemicals are pushed down holes under high water pressure. The water that returns to the surface is known as produced water. Produced water requires appropriate treatment to meet acceptable standards before disposed via injection wells or saltwater disposal facilities.
The first issue that oil and gas operators face are problems with maintaining a sustainable supply of freshwater to continue operations. Freshwater is already in short supply for several other critical sectors spanning irrigation, agriculture and industrial, which makes it difficult to obtain. Additionally, existing local water sources do not often provide enough water to support fracturing operations because each operation may take millions of gallons of water per day. As such, these water sources do not suffice.
Furthermore, increased oil and gas activities have led to growing saltwater intrusion in injection wells, leading to higher total dissolved solids (TDS) levels. Due to density and high pressure, saltwater can easily enter the subsurface layer of freshwater aquifers and create a contamination hazard for the groundwater sources. Injection wells approach saturation limits after repeated injections, and regulations require oil and gas operators to treat the brine concentrates prior to injecting, thereby making the entire process even more complex, time-consuming and expensive.
To add further costs, operators need to consider costs for both trucking and disposal of water. These costs have skyrocketed due to rapidly expanding drilling, fracturing and production operations, and they can significantly affect profit margins from any operation.
“Operators are seeking alternative solutions and technologies designed to treat produced water and flowback water at the wellhead and are capable of recovering and restoring water for reuse in drilling and fracturing operations.”
To address these concerns — including significant costs for trucking and disposal, complex environmental regulations and scarcely available freshwater — more operators are seeking alternative solutions and technologies designed to treat produced and flowback water at the wellhead and are capable of recovering and restoring water for reuse in drilling and fracturing operations. A system that can treat a variety of complex produced and flowback waters helps fill the need for freshwater by producing recycled water of a suitable quality for downhole fracturing operations. This eliminates the logistical expense to transport freshwater to the wellheads and haul high TDS of saturated brine water for disposal to the disposal facilities.
Solutions for water reclamation of produced water and flowback water
Selection of the best technology for reclamation of produced water and flowback water varies depending on production volumes, wastewater quality, site proximity, regulatory requirements, budgets, footprint and other site-specific parameters. Several advanced technologies with advanced treatment processes help make oil and gas water reclamation more affordable, environmentally friendly and capable of complying with stringent environmental regulations, negating the need for injection wells.
One solution that fracturing operators are exploring is a modular design approach. Advanced technologies that offer modular design allow the operator to develop specific processes by considering the level of water contamination, the desired water quality, environmental regulations and cost.
Prior to the development of full-scale design, laboratory water testing is conducted to determine the type of contaminant(s) present in the source water. Pilot studies can then be conducted for process stimulation and system optimization using real-time critical operating data collection. The pilot demonstrates the efficacy of selected technology such as bioremediation, combinations of several advanced flash distillation processes, advanced disinfection and validating the application of the treatment process to a specific water stream. Specific process improvements are targeted during the piloting for establishing an optimal design along with the capital expenditures and operating expenses. A full-scale system is then designed based on available pilot data.
Mobile treatment units with modular configuration allow for easy integration into existing systems at the wellhead site and enable processing near the wellhead itself. It is also capable of using flare gas from the wellhead and recapturing heat throughout system operation for energy savings that can offset the overall cost of operations.
“Mobile treatment units with modular configuration allow for easy integration into existing systems at the wellhead site and enable processing near the wellhead itself.”
Another approach that some fracturing operators are exploring is the use of emerging water technologies such as bioremediation through proprietary bacteria and advanced water reclamation processes. Using the power of biology to restore the ecosystem, new forms of bacteria including pseudomonas bacteria are introduced to eliminate hydrocarbons, TDS, total suspended solids (TSS), chlorides, algae, nitrates and phosphates. This approach is also approved by the Toxic Substances Control Act (TSCA), Environmental Protection Agency (EPA) and National Contingency Plan (NCP), so operators can successfully deliver water suitable for drilling and fracturing operations while remaining conscious of the surrounding environment. Treated water is filtered for immediate on-site use, which eliminates costly transportation and waste haul-off charges, reduces liability by handling the problem on-site and provides significant cost savings per project with success achieved within days or months.
Resource recovery of treated produced water
Some of the advanced water reclamation technologies commonly deployed by oil and gas operators are capable of handling TDS concentrations approaching saturation levels of up to 250,000 parts per million (ppm). The water produced ultimately has TDS concentrations in comparable range to freshwater and even better quality in some cases. Depending on a producer’s budget, project needs and output requirements, modules with advanced processes can be added to the treatment chain to accomplish goals such as zero liquid discharge solutions that have no liquid discharge. Output stream may be only dry salt crystals or salt slurry, depending on feedwater constituents. Additional byproducts can be produced with additional recovery processes for oil, hydrocarbons, salt and others. Treated product water can be released in the form of clean steam; recovered hydrocarbons can be sold to secondary markets; and recovered materials and salt are dried and can be sold as a commodity. All of which create previously unrealized revenue. Some of the known traditional processes — thermal, mechanical, distillation, physical and chemical separations — can be combined and applied in the overall design of a single processing system. These techniques are employed for a targeted effluent, creating a series of products from the effluent itself and residual waste. Resource recovery processes are added to develop viable byproducts, and some of which can even handle the final 20 percent of the hydrocarbons, salt and oil combination.
Conclusion
The aforementioned technologies provide advanced solutions to the oil and gas market for water reclamation and reuse and enable produced water reuse at costs that are competitive with current freshwater prices in the oil and gas market. They allow producers to eliminate the need of the disposal well and mitigate expensive logistics associated with hauling away disposals as well as trucking purchased water to the wellheads. Cost-reducing technologies can increase efficiencies and leave sites in a stronger state that benefits the regional environment.
Alan Murphy is the executive vice president of business development at Alpha Water Resources. He has been in the water business for more than 25 years, experienced with municipal, industrial and commercial water and wastewater treatment facilities in consulting, design, operations, management and project oversight and construction throughout Texas and worldwide. Murphy is a licensed electrical journeyman in Texas and TCEQ Level III Water Treatment Specialist certified in Texas. He has also been involved in design, build and operate projects for municipal facilities and supported with regulatory compliance (state and federal), electrical, automation controls, process design, troubleshooting services, complete installation, full-scale commissioning, training and plant operations.
Varkha Agrawal is a project engineer at Alpha Water Resources with more than 10 years of experience in providing innovative designs for water and wastewater treatment. With a bachelor’s in civil engineering and a master’s in environmental engineering, Agrawal is adept at analyzing, modeling and designing complex water and wastewater treatment systems and applying advance treatment processes. She has worked on state regulatory compliance in obtaining pilot exception approvals, pilot study protocol and pilot study reports and brine discharge permits from the Texas Commission on Environmental Quality. Agrawal has served as a project manager for projects including client relationship management, contract preparation, project planning, budgeting, deliverables and performance milestones.
