This connection, or nexus, between energy and water highlights the importance of these resources for society and the environment. As such, we work to prevent adverse impacts to water resources from our withdrawals and discharges and prudently manage the water we do use.
ExxonMobil develops and implements water management strategies, most notably at the local level, that take into consideration quality and availability, as well as potential trade-offs, such as varied operational efficiencies, increased energy use or the consequences of producing more concentrated waste streams. For more information about how ExxonMobil manages water, see our current issues page.
In 2015, the net freshwater consumption at our operations was 300 million cubic meters, representing more than a 5 per cent decline since 2007, in part due to the development and implementation of local water management strategies. ExxonMobil’s total freshwater consumption includes use by refineries and chemical plants, oil and gas production, and onshore shale resources development in the United States.
We recognise that some of our operations use significant amounts of water, and we understand the necessity to engage with stakeholders regarding their concerns about the use and protection of local water resources. For example, the amount of water needed to hydraulically fracture a typical shale gas well ranges from 3 million to 4 million gallons. However, it is important to put this quantity into perspective. For example, the World Resources Institute found that the average golf course in the United States uses 4 million gallons of water in less than one summer month. In fact, hydraulic fracturing operations account for less than 5 per cent of our total water consumption.
As illustrated below, the amount of the freshwater needed to produce an identical unit of energy from natural gas is less than for a variety of other energy sources, including hydroelectric power and ethanol. According to a recent study by the U.S. Department of Energy’s National Energy Technology Laboratory, shale gas production uses about 10 times less water than is used for coal production, and 1,000 times less water than is used for fuel ethanol or biodiesel production. Even so, we continue to look for opportunities to reduce our water use.
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ExxonMobil seeks to continuously improve the development and implementation of water management strategies. Part of this effort involves improving our understanding of not only the quantity of our water consumption, but also when and where this consumption occurs. In 2015, ExxonMobil collaborated with ETH Zurich, one of the leading international universities for technology and the natural sciences, to co-author a peer-reviewed paper on improving the capability to assess water stress indices. The purpose of the paper was to explain the impacts of freshwater consumption in life cycle assessments (LCA) of comparative energy sources. In particular, the paper highlights the importance of regional and seasonal variations when considering water stress as part of an LCA.
Based on our analysis using the latest version of the oil and gas industry global water tool, almost 40 per cent of our major operating sites are located in areas identified with the potential for water stress or scarcity. Where appropriate, we conduct a detailed local analysis of specific water use-related risks and develop site-specific management strategies such as the deployment of water conservation technologies, the use of alternative freshwater sources, recycling of municipal and industrial wastewater and harvesting of rainwater.
For example, conventional methods of dust suppression can require large amounts of freshwater to maintain safe working conditions. By applying a biodegradable dust-control product to the roads at our oil sands operations in Kearl, Canada, we were able to significantly reduce the amount of water required to manage road dust. In 2015 alone, the Kearl oil sands operations saved an estimated 36 million gallons of water.
ExxonMobil responsibly manages process wastewater and produced water from our operations, and we proactively look for opportunities to address any potential water quality issues. For our Upstream projects, our Water Management Standard outlines minimum expected environmental performance and mitigation measures. This Standard establishes the planning and design basis for reducing impacts to surface waters, groundwaters, estuarine and marine waters as well as to the associated habitats and users, from a use or consumption viewpoint as well as with regard to discharge quality.
Produced water, a byproduct of upstream oil and gas operations, is typically managed onshore by injection into deep underground reservoirs. For offshore production facilities, produced water is managed by re-injection into an associated reservoir or treatment and discharge into the marine environment in accordance with applicable regulatory requirements. From 2014 to 2015, ExxonMobil conducted a series of sampling and modeling initiatives in Australia to evaluate how produced water discharges might interact with the local marine environment. The results showed the amount by which the concentration of discharge constituents vary day-to-day and the way discharges mix in the sea with the surrounding currents. These factors are critical to understanding the overall environmental impacts of the discharges. The study will continue in 2016.
The topic of induced seismicity has gained more attention over the past few years. In some instances, due to unique geologic conditions, oil and gas operations can trigger seismic activity. Such operations may include reservoir depletion, wastewater disposal injection and in rare situations, hydraulic fracturing. We recognise the issue of oil and gas operations inducing seismicity is a matter of public concern. No matter the cause — natural or human induced — local communities have concerns about seismic activity in their area.
We support risk management and mitigation approaches that consider various mitigation methods for the relative risks in a given context, including the assessment of factors such as fluid volumes, formation character, tectonic setting, operating experience and local construction standards. For example, at XTO Energy, we follow a disciplined injection well siting protocol, which uses available data, including federal, state or internal seismic information, to conduct a risk assessment prior to siting a disposal well. Some government agencies mitigate seismicity risk during development with operational “traffic light” systems.
We believe it is important to gain a better understanding of all types and sources of seismic activity. By supporting research at universities, cooperating with governmental agencies and conducting our own research, we are contributing to developing a better understanding of seismicity. We believe having a science-based risk management approach is an essential foundation for evaluating events and avoiding adverse effects of seismicity. In addition, ExxonMobil has been strengthening our risk management systems related to this challenge and proactively sharing our findings with local communities, academia and regulators.
In 2015, ExxonMobil provided technical leadership to States First — a multi-state initiative aimed at facilitating innovative regulatory solutions for oil and natural gas producing states — for its induced seismicity working group’s primer on potential injection-induced seismicity associated with oil and gas development. Specifically, the primer provides guidance on evaluating risks associated with induced seismicity from wastewater disposal wells and helps regulatory agencies develop strategies for managing and mitigating risks. Research findings for the primer indicate that risk management, risk mitigation and response strategies are most effective when specific local geologic conditions and operational situations are considered. Accordingly, the primer does not recommend specific policies, emphasising that a one-size fits all regulatory scheme would not be flexible enough to account for area-specific risks and concerns.
Executive director, Groundwater Protection Council
“State agencies are on the forefront of oil and gas regulation and are diligently working to address the safety and environmental issues surrounding modern energy development. Knowing how to best mitigate and manage the risk of induced seismic events requires multidisciplinary scientific understanding that often reaches beyond the domain expertise of any individual state agency or regulatory body. ExxonMobil’s technical leadership alongside the contributions of academia, environmental stakeholders and regulators provides a valuable contribution in helping States First develop a guide for regulators that is grounded in the best available science.”