Joint Sustainability of Petroleum Energy Production and Water Resources

We all agree on the urgent need to develop solar, wind, and biofuel energy resources, but this editorial is not about alternative energy. We should first admit that all of us depend on petroleum energy consumption. We drive to work, heat our houses, fly to conferences or to vacations on sunny beaches, and buy goods from the grocery store. However, we also face an economic imperative to reduce consumption, particularly our reliance on foreign oil and gas. As our petroleum reserves decline, energy companies are focusing on development of natural gas and unconventional reserves such as oil shale and coalbed methane. Development of these resources will consume significant amounts of water and generate large volumes of water that require treatment. Many of the most promising unconventional deposits are in the western United States and Canada, where water resources are scarce. Thus, the joint sustainability of petroleum-energy production and water resources has emerged as an evermore important technical challenge. As hydrogeologists, we are interested in the sustainability of our water resources. As citizens, hydrogeologists care about the sustainability of our energy resources. Oil and gas professionals have the same interests but a fundamentally different perspective on water. Water is viewed as a waste product from petroleum production and is not historically associated with water resources. This view is woven into business models and regulatory structures. As hydrogeologists, we recognize the environmental, social, regulatory, and legal limitations of this view. Fortunately, joint sustainability of oil and gas energy and water is within our grasp. However, to achieve this sustainability, we must overcome complex technical and regulatory issues. For example, coalbed methane extraction requires dewatering coalbeds, units that are often interbedded with aquifers. The shortand long-term effects of large withdrawals from coalbeds on hydraulically connected aquifers and associated streamflow are often not considered, let alone quantified rigorously. Produced water is disposed of rather than reclaimed, usually by surface discharge or infiltration, without much regard to the watershed hydrology. This ‘‘waste product’’ can be nearly potable to saline water that could be used beneficially with appropriate treatment. What if we were to treat this ‘‘waste’’ as a resource? What if we were to recognize and actively manage the interactions of the entire system, including both water and energy resources? This approach requires overcoming many hurdles besides professional perspectives. For instance, produced water, ground water, and natural resources are typically regulated by separate governmental agencies. It is not clear which laws take precedence when they suggest conflicting requirements. Current watershed models do not include consideration of subsurface processes related to energy extraction nor do current energy extraction models consider impacts on overand underlying aquifers and streams. Legal or regulatory precedents often result in use of simple screening models for water resources assessment rather than rigorous hydrologic modeling now commonly used by hydrogeologists. Thus, education of the public, energy companies, judges, attorneys, and regulators on the current best practice for water resources assessments needs to be a priority. The optimum outcome requires comprehensive and integrated water management planning that provides for energy-related extraction, reclamation of produced water, or disposal that minimizes undesirable watershed impacts. Oil shale development presents a similar challenge. While the extraction technology is not fully developed, all proposed methods require significant amounts of water and will produce considerable volumes of wastewater. In situ retorts have an unknown impact on ground water quality. Much of the water must come from the Upper Colorado River basin, which supplies seven western states and Mexico. Thus, integrated hydrologic assessments must be performed to ensure future sustainability of water for energy production, development, and natural resources. For both technologies, models should be developed that can estimate the watershed-scale effects on water quantity and quality. Technology for treating coproduced water for environmental, industrial, or residential use should be developed concurrently with production technologies. A reasoned approach would integrate water resource assessment with energy exploration and production. Surface and ground water modeling conducted jointly with reservoir engineering studies can steer drilling that balances the optimal hydrocarbon production and minimizes disturbance to water resources. In the meantime, policy makers should construct modern guidelines that recognize beneficial use of coproduced water. Water policies inconsistent with joint sustainability must be revisited. Joint research programs in energy-water sustainability should be a priority of funding agencies. Perhaps most importantly, transparent, honest discussions must begin among energy professionals, policy makers, regulators, legal experts, water-resources professional, and stakeholders. We are all citizens who depend on the joint sustainability of water and energy resources.