In the oil and gas industry, drilling, completions and production requires and yields significant amounts of water. Sometimes, this water can be recycled/reused. Sometimes it can’t. The Water Challenge (WC) Program was created recognizing that continuous improvement is not only feasible, but also essential for both operational and environmental sustainability.
HARC’s Environmentally Friendly Drilling Program (EFD) was launched to bring unbiased science to bear on often-vexing environmental issues associated with “unconventional” methods, such as hydraulic fracturing, that are used to explore for and produce natural gas.
Partnering with industry, academic and environmental organizations, EFD works on issues including the impacts to land, water and air that have drawn increasing attention and spurred wider public concern during the accelerating boom in natural gas activities in shale regions of Texas and other states in recent years.
Rich Haut, EFD’s director, frequently confers with the program’s partners to learn about their concerns and needs. Inspired by such conversations, EFD initiated a new project about a year ago to conduct research aimed at helping companies reduce emissions of air pollutants from their natural gas activities.
The project, called Powered by Natural Gas (PbNG), is coordinated by Carolyn LaFleur, a civil engineer with extensive industry experience who joined HARC as a research associate in 2012. The project’s name reflects its research focus – the accelerating interest of various energy industry companies in replacing diesel fuel with cleaner-burning natural gas to power equipment used in exploration and production.
“Natural gas fuel has great appeal because it offers opportunities to reduce pollution and other environmental impacts along with cost savings,” LaFleur said.
Substituting natural gas could yield air quality benefits by lowering emissions of potentially health-damaging air pollutants from diesel engines, including tiny airborne particles and nitrogen oxides, which combine with other pollutants in sunlight to produce ozone, the main component of urban smog.
“Technologies that will utilize natural gas in new and more efficient ways are burgeoning along with development of domestic gas supplies,” LaFleur said. “Research is important to understand the benefits and limitations of these new technologies.”
The first phase of the research effort at the heart of the Powered by Natural Gas initiative is a conceptual study to determine, in part, how natural gas can be used in drilling and hydraulic fracturing operations, both to reduce diesel emissions and reduce the distances involved in transporting liquefied natural gas to well sites.
PbNG has already published the first in a series of planned white papers, “The Basics of Natural Gas Power & Fuel” and will publish the second one shortly. To disseminate information and exchange ideas, the initiative has also co-sponsored a couple of workshops for industry officials in regions where air quality concerns surrounding oil and gas operations have received growing attention – one in San Antonio last May and one in the Pittsburgh area last September.
The white paper series, LaFleur said, is intended to inform industry officials – not just engineers, but also people such as business analysts – about the technologies that are emerging for substituting natural gas for diesel and the related issues.
One such technology that has received a lot of attention – known as “dual fuel” and “bi-fuel” – involves displacing some of the diesel used in drilling and fracturing equipment with natural gas, burned at the same time.
The initial PbNG white paper explains this approach:
“Dual fuel diesel displacement can be implemented with a number of available equipment options. In these systems, natural gas fuel in vapor phase is introduced into the air intake system of the engine. The two fuels are blended together and are ignited by compression in the engine cylinder.”
Many factors affect the actual substitution rates that can be achieved, but fuel mixtures involving 50 percent to 70 percent natural gas have been reported, the white paper adds.
PbNG plans to step up its research on emissions from engines burning both diesel and natural gas simultaneously.
“HARC has the capability to perform actual physical measurements of the composition of diesel engine exhaust from dual fuel combustion,” LaFleur said. “We are currently engaged in this kind of work, and actively seeking further opportunities to apply this measurement technology.”
One EFD sponsor, Keane Group, a service company whose activities include hydraulic fracturing, is fitting some of its pressure pumping fleet with dual fuel engines and has offered HARC the opportunity to study emissions in the field, she said.
The ultimate goal for efforts to substitute natural gas in drilling and fracturing operations is the development of technologies that can be situated very near to the places where natural gas is being extracted from underground formations, LaFleur said.
In using natural gas near its source – so-called “field gas” , companies can reduce both the costs and the risks of so-called “fugitive” emissions, or leaks, of methane – main component of natural gas – from points in the system used to transport it, like pipelines, compressor stations and trucks, she said.
Methane leaks in the production and distribution of natural gas have become a hotly debated issue related to global climate change. Burning natural gas yields much less carbon dioxide – the principal human-produced greenhouse gas driving the global warming process – than other fossil fuels. But methane, when it leaks into the atmosphere as an unburned gas, is itself a greenhouse gas, with more warming potency on a molecule-by-molecule basis than CO2.
Concerns about methane are an integral part of the PbNG effort, LaFleur said.
The issue “was on our radar last May when we hosted the workshop in San Antonio on this topic,” she noted. At that time, one of the invited speakers who urged attention to the methane issue’s importance was Ramon Alvarez, an Austin-based scientist with the Environmental Defense Fund (EDF) an advocacy group with which HARC collaborates on various projects.
(HARC’s Alex Cuclis, Air Quality and Emissions, will be participating in a two-year study to test less-expensive remote-sensing devices for measuring methane leaks at oil and gas facilities.)
“Using ‘field gas’ as fuel near the wellhead where it is produced greatly shortens the supply chain,” LaFleur said. “As with other locally sourced commodities, impacts associated with processing and transportation are significantly reduced.”
Emissions of methane, she added, “are a key concern with expanded production and utilization of natural gas, and must be addressed with engineering controls throughout the system.”