Introduction
Water management in hydraulic fracturing, or fracking, is a critical process that encompasses the entire water lifecycle, from acquisition to disposal. The significant volume of water needed and the subsequent creation of highly contaminated wastewater pose major environmental and operational challenges.
This article explores the aspects of water management in hydraulic fracturing, including sourcing, use, treatment, recycling, disposal, environmental impacts, and the latest innovations.
Factors influencing water use:
Well design:
Horizontal wells, which have longer sections that contact the rock, generally use more water than vertical wells.
Number of fracture stages:
The process is repeated in stages along the horizontal wellbore, and the more stages, the more water is needed.
Rock properties:
The specific characteristics of the shale formation being targeted influence how much water is required.
Water recycling and reuse:
Operators can treat and reuse water from previous fracking operations, which reduces the need for fresh water and lowers overall water consumption.
The Role of Water in the process:
- Fracturing the rock:
A mixture of water, sand, and chemicals is injected into the well at high pressure.
- Propping open fractures:
The pressurized fluid fractures the shale, and the sand (proppants) keeps the fractures open to allow oil and gas to flow out.
- Fluid return:
After the fracturing is complete, some of the injected water mixture flows back to the surface, often mixed with naturally occurring brine water and oil/gas.
Water sources and reuse:
Surface and groundwater:
Most of the water used comes from surface sources like rivers and lakes, or groundwater.
Treatment and reuse:
In some water-scarce areas, well operators treat the returned water for reuse in future fracking operations, improving water use efficiency.
Sustainability:
Water is a critical resource, and managing its availability for energy development is vital.
Regulation:
Agencies in some regions, such as the Alberta Energy Regulator (AER), regulate water use, issue licenses, and monitor water sources to ensure sustainability.
Water use intensity:
The metric of water use intensity (nonsaline water used per barrel of oil equivalent produced) can show how the intensity decreases over the well’s productive life as the number of wells producing hydrocarbons increases.
Stages of Water Management in Hydraulic Fracturing:
- Water Sourcing:
This stage involves identifying and securing water for the fracturing process. Sources can include surface water (rivers, lakes), groundwater (aquifers), or municipal supplies. Reused or recycled water from previous operations can also be a source.
- Water Transfer & Usage:
Water, along with sand and chemical additives, is transported to the well site. The high-pressure injection of this fracturing fluid creates fractures in the rock formation to extract oil and gas.
- Wastewater Management:
After the well is fractured, a significant volume of “flowback” water returns to the surface. This water is heavily contaminated with dissolved solids and other substances and poses environmental and health risks.
- Water Treatment & Reuse:
Flowback water is treated to remove contaminants, often at mobile or centralized treatment facilities. Common technologies include electrocoagulation to remove suspended solids and coagulate them for removal. Treated water can then be reused in subsequent fracturing operations or other well construction activities.
- Disposal & Monitoring:
Water that cannot be reused is disposed of in accordance with regulations. Methods include evaporation ponds or enclosed tanks. Continuous monitoring of water quality, usage, and regulatory compliance is essential throughout the entire process.
Treatment and Recycling of Frac Water:
The specific treatment process varies depending on the water’s contamination level and the required purity for reuse, but generally includes:
- Flowback and Produced Water Collection:
Water containing fracking fluid, sand, and reservoir byproducts is collected from the well.
- Mechanical Separation:
Solids are removed through mechanical separators, hydrocyclones, or other filtration systems.
- Chemical Treatment:
pH Adjustment: The water’s pH is often adjusted by adding alkaline agents.
Coagulation and Flocculation: Coagulants are added to form small particles (agglomerates) which then clump together (flocculation).
Oxidation: An oxidizing agent is introduced to oxidize and remove organic contaminants and reduce bacteria.
- Filtration:
Further filtration, which can include specialized filter media, is used to remove remaining solids and finer particles.
- Disinfection and Sterilization:
Proprietary processes, sometimes including chemical-free oxidation or other methods, are used to disinfect and sterilize the water, eliminating harmful bacteria.
- Water Quality Assessment:
The treated water is tested to ensure it meets the stringent requirements for reuse in fracking operations.
Common Water Disposal Methods
Surface Discharge:
Treated water is discharged into natural water bodies like rivers, lakes, or the ocean.
Water Reuse/Recycling:
Treated water can be reused for non-potable purposes, such as:
Irrigation: Watering landscapes or agricultural crops.
Industrial Applications: For cooling processes or other industrial needs.
Groundwater Recharge: Infiltrating water back into underground aquifers.
Subsurface Discharge Methods
Septic Systems/On-site Systems:
Common in rural and suburban areas, these use a septic tank to settle solids and a leach field (or soil absorption area) to disperse liquid effluent into the soil, where it is naturally treated by soil organisms.
Deep Well Injection:
A method to dispose of produced water or other industrial wastewater by pumping it into deep, porous geological formations.
Methods Used in Specific Contexts
Wastewater Treatment Plants/Sewer Systems:
For urban areas, water is transported via a waterborne sewer system to a central treatment plant before disposal or reuse.
Evaporation Ponds:
Water is contained in ponds, where it evaporates into the atmosphere.
Constructed Wetlands:
Engineered systems that mimic natural wetlands to treat water through biological processes.
Chemical Toilets:
Used in mobile settings like trains or planes to contain and treat waste chemically before disposal.
Conclusion
Water is both a critical enabler and a major challenge in hydraulic fracturing operations. As public scrutiny increases and environmental regulations tighten, efficient and responsible water management is essential—not just for operational success but also for long-term sustainability and community acceptance.
READ: Water Management in Fracking