Abstract
This paper presents the basics of hydraulic fracking and discusses various possibilities of wastewater management technologies. Factors include water composition, delivery methods, and purification processes. The paper outlines the environmental impacts of hydraulic fracturing which highlights the importance of wastewater treatment. The main scope of the paper investigates the viability of various wastewater treatment options in resolving a critical resource issue.
The methodology consists of conducting in-depth research on the topic and expanding into fundamental concepts of water management technologies that the industry utilizes, as well as discussing and presenting an expert opinion. These findings are useful in identifying solutions for the expansion of hydraulic fracking as a primary method of petroleum extraction in the world experiencing an increasing scarcity of clean water.
Introduction
Hydraulic fracturing, also known as fracking, is an innovative and rapidly developing technology in the petroleum industry. It is gaining popularity over traditional extraction technologies since it introduced horizontal drilling techniques which allow tapping previously inaccessible rock formations for hydrocarbons. Hydraulic fracturing is highly complex, and the industry continues to face a myriad of challenges in its implementation and environmental safety.
This report investigates the development of water treatment technologies that maintain a vital role in the fracking process. It focuses on a general audience with a basic understanding of petroleum engineerings, such as students or journalistic investigators, seeking to learn information on the complexities of the fracking process. Hydraulic fracking is an efficient innovative technology for petroleum extraction but requires addressing the issue of water management to maintain viability long-term.
Basics of Fracking
Between 2005 and 2013, natural gas production in the United States increased by 35% stimulated by the use of hydraulic fracturing of natural gas from inaccessible shale formations.1 Hydraulic fracking is an extraction process for both, oil and natural gas, which consists of injecting water, mixed with sand and specialized chemicals, into wells. Injected fluid resists flow, causing a rise in the wellbore pressure to a value known as “break-down pressure.”2
It exceeds the sum of compressive stress and strength of the shale formation. Extremely high pressure creates a fracture that opens and cracks pores in the shale formation, releasing hydrocarbons as the injecting fluid flows.3 The fracture widens gradually until there is enough space to fit a propping agent, which consists of corrosive resistant sand or ceramic beads meant to maintain the opening. Hydraulic reaches petroleum reserves located in shale formations. Horizontal drilling allows for a wider application of fracking, causing a debate over the viability of such methods.
Water Composition and Environmental Impact
Pore creation pumps water into the well, and eventually, it flows back for collection. However, this water contains a concentration of chemicals, heavy metals, salts, oil greases, and a combination of volatile and semi-volatile soluble organics. Other substances present in the water composition include reducing polymers, corrosion and scale inhibitors, and biocides. Chloride levels increase from 82 mg/L to 98,000 mg/L in 14 days after drilling.4
Furthermore, levels of radium and barium, naturally occurring radioactive materials, significantly exceed drinking water regulation set by the Environmental Protection Agency. These substances are necessary for drilling operations as they mitigate the difficulty of the fracking process. However, extensive environmental and groundwater contamination occurs, leaving the water unusable for any other purposes.
Water volume and composition are vital issues as well. Fracking requires significant amounts of water of approximately 4 to 6 million gallons to stimulate a contemporary unconventional well.5 Contractors collect water from ground and surface sources alike, which limits its availability for other uses in the local area. Water management is costly and leaves a tremendous ecological footprint as part of the fracking process. Without a system of waste treatment in place, the water could contaminate nearby areas leading to health issues and casualties. Therefore, water management is synonymous with hydraulic fracking as a technology that presents technical and economic challenges.
Wastewater Management
Freshwater supply is becoming increasingly difficult and more expensive to obtain for hydraulic fracturing purposes. In several states, regulation governs water acquisition. In areas such as the Missouri River watershed, the Army Corps of Engineers prohibits the acquisition of water from the river for the petroleum industry as this creates a shortage for local farmers. A series of hydraulic fracturing wells require four to eight million gallons of water in one week, and up to 6 billion annually, for one formation.6
Petroleum production companies frack well numerous times over a productive life of up to twenty years.7 The growing value of water supply and strict regulation motivates hydraulic fracturing operations to consider options in wastewater management.
The fracking process recovers half of the water as “flowback.” It contains high concentrations of chemicals and brine. It is both challenging and costly to treat. Companies inject wastewater into deep wells, which do not require sophisticated treatment. However, recent regulation bans this common practice in many jurisdictions. Currently, the reuse of flow back water is 13 percent, but regulation and freshwater costs will increase the rate.8 The development of appropriate technologies would significantly reduce the transportation costs for operators.
Without the availability of deep-oil wells, companies will consider reusing wastewater. Operators filter for metals, hardness, and bacteria counts and blend flow back with fresh water to be used at another site. Each drilling company maintains its unique specifications, but the dilute rate can be 20:1, leaving a very low percentage of flow backwater. Wastewater filtration occurs until the limit exceeds 10,000 ppm.9 Oxidation introduces chemicals to eliminate organic compounds. Reverse osmosis cleans through a membrane filter. Freshwater municipal systems utilize these technologies, as proven reliability leads to wider adoption.
Centralized vs. Modular Treatment Systems
A centralized approach to water management seeks to optimize the utilization of water resources while combining the aspects of treatment and recycling of wastewater. Centralization provides filtration to a large number of wellheads at the initial stages and throughout the operating lifecycle. A centralized approach supports accessibility and yields alternative sources of water such as municipal facilities. Shale formation development through fracking is a long-term process. Most water management solutions concentrate on short-term operations.10 The strength of a centralized system is the recycling and reuse of flowback wastewater.
It eliminates off-site transportation or mobile filtration systems which are less effective. A centralized system offers viable and long-term management of fracking wastewater. The treatment facilities collect both flows back and produced wastewater from any oil or gas well within a range of 50 miles, directly through pipeline transportation.11 A centralized system promotes wider adoption of the technology in the United States.
As water arrives at a centralized plant, the operator confirms its location, target usage specifications, and requirements of the drilling company. The system processes the water and pipes it back to the well site. Overall, centralized wastewater management offers a broader scope of filtration and treatment options. These include multi-stage separation that separates chemicals and suspended solids. Reverse osmosis removes heavy metals, while dissolved air flotation and bactericide eliminate contaminants or organic compounds.12 Overall, centralized systems are more permanent, with integration into water sources and locations for water disposal.
A modular water management approach is a mobile, portable water treatment and sewage system which can modify its network with additional treatment units. The drilling company adds and removes units dependent on specific requirements, scaling the system by water treatment needs. This provides flexibility and cost-efficiency. Modular systems are portable, delivering shipping containers to virtually any location globally. It makes modular systems attractive for remote locations, particularly from an environmental standpoint due to a low ecological footprint. Furthermore, the technology is efficient, easy to implement, and deployable, maintaining low capital and operating costs.13
Modular technology is adaptable for treating wastewater in either batches or a continuous cycle. Most modern modular systems utilize a combination of a chemical filtration system and a membrane biological reactor.14 These reactors implement high-pressure membranes for reverse osmosis and nanofiltration. Novel membranes conduct forward osmosis and membrane distillation. There are also electric processes such as CDI and electrodialysis. Thermal technologies combine vapor compression, multi-stage flash, distillation. Evaporation and crystallization are also available.15
Discussion
The petroleum industry is actively seeking methods to mitigate the environmental issues surrounding hydraulic fracturing. Treatment and reuse of water consist of developing technological capabilities, reforming logistics and economics with the tools to improve water management. Water infrastructure must strategically develop to account for the operating life of a well. Operators and producing regions rarely investigate or quantify the costs of water management and logistics.
Since wastewater management is dependent on local factors such as disposal options, state regulations, and availability of freshwater basins, water-cost calculations neglect these variables. Obtaining, cleaning, storing, and disposing of water in hydraulic fracking reaches up to 30% of total operational costs.16 If drilling companies and the public were more aware of these significant costs and logistical issues of water delivery, it could lead to reforms for the reuse of water on site.
Conclusion
Drilling operators face a wide variety of water management challenges when using unconventional methods such as fracking. Water quantities, storage, transportation, characterization, and treatment require significant innovation. However, effective management and treatment lead to successful shale fracking operations. Investment into water planning and procuring avoid disruptions with fluid volume and delivery on site. Environmental concerns, social pressures, and regulatory limitations influence the logistics and economics of freshwater use. In response, petroleum companies develop innovative technologies for the improvement of flowback water and infrastructure to minimize dependence on freshwater sources.
References
Advanced Water Treatment for Hydraulic Fracking Water. NSF IUCRC. Web.
Botte, G. G. 2017. Electrochemical Technologies for Water Treatment, Management, and Efficiency. The Electrochemical Society Interface. 26(2): 53-61.
Chen et al. 2014. Hydraulic Fracturing: Paving the Way for a Sustainable Future? Journal of Environmental and Public Health. 2014: 1-8.
Easton, J. Fracking Wastewater Management. WWI. Web.
Haluszczak, L. O., Rose, A. W. and Kump, L. R. 2013. Geochemical Evaluation of Flowback Brine from Marcellus Gas Wells in Pennsylvania, USA. Applied Geochemistry. 28(2018): 55-61.
Hardcastle, J. Fracking Wastewater Treatment Technologies: Which Will Emerge as the Most Popular? Environmental Leader. Web.
Hydraulic Fracturing. WesTech. Web.
Smith, A. P., Van de Ven, C. J. C., and Richardson, S. D. 2017. Current Water Management Practices, Challenges, and Innovations for US Unconventional Oil and Gas Development. Current Sustainable/Renewable Energy Reports. 4(4): 209-218.
Appendix A: Diagram of the Hydraulic Fracking Process
Appendix B: Modular Transportable Internal Membrane Reactor System
Footnotes
- Advanced Water Treatment for Hydraulic Fracking Water 2016.
- Chen et al. 2014.
- See Appendix A.
- Haluszczak, Rose and Kump 2013.
- Chen et al. 2014.
- Easton n.d.
- Ibid.
- Hardcastle 2016.
- Hydraulic Fracturing n.d.
- Easton 2014.
- Easton 2014
- Ibid..
- Ibid.
- See Appendix B.
- Botte 2017.
- Smith, Van De Ven and Richardson 2017.