PITTSBURGH—The benefits of natural gas-powered electric fracturing has been the subject of much discussion in the shale industry as a growing number of producers seek ways to lower their emissions.

“The debate between electric and dual fuel has really exploded over the past year,” Tom Cannon, drilling and completions manager for Seneca Resources, told attendees of Hart Energy’s DUG East Conference.

One of the few to share their decision-making analysis on electric frac, or e-frac, fleet adoption, the Pennsylvania producer presented its findings alongside partner NexTier Oilfield Services at DUG East in December.

Seneca Resources, the E&P segment of diversified energy company National Fuel Gas Co., operates roughly 1.2 million net acres producing over 1 Bcf/d of natural gas in the Marcellus and Utica shale plays. The company recently achieved certification of 100% of its Appalachian natural gas production under Equitable Origin’s EO100™ standard for responsible energy development, a series of rigorous ESG performance targets.

According to Seneca Resources, natural gas-capable and 100% electric fleets made up about one-third of all U.S. land fleets in 2021. But they expect that by the end of the year, those will account for more than half of all fleets in the U.S.

Cannon explained that Seneca has employed several drilling and completions emissions reduction initiatives, including using dual fuel rigs and fracs, natural gas water transfer pumps, and natural gas-run water wells, natural gas generators that power outside lighting offices and camps.

Seneca was also considering adopting e-frac into their operations but first wanted to understand what was the best fit for the company, which led it to pioneer a study with NexTier Oilfield Solutions.

Launched in July 2021, the study by Seneca and NexTier aimed to provide the shale industry with a comparative insight on the emissions profile of hydraulic fracturing technologies utilizing Tier 2 diesel and dynamic gas blending (DGB) engines, Tier 4 diesel and DGB engines, natural gas-powered turbine engines, and e-frac equipment powered by natural gas-fueled reciprocating engines.

“We really tried to get a study that was as unbiased as possible,” Cannon said. “We didn’t have any bias toward any one of these technologies. We really wanted to understand what truly is the best with emissions, and use that emissions data to make our best decisions as Seneca.”

Cannon explained that compared to diesel fuel on a per gallon basis, natural gas costs 33 cents per gallon, where diesel delivered to location costs $3. But Seneca evaluated different frac fleet options on availability, horsepower requirements, flexibility and reliability as well.

“Does the fuel savings offset the market premium of natural gas-capable fleets, mainly because you’re not only looking at the fuel savings, but you’re also looking at the market increase price at what these new generation equipment is coming out,” he said. “Limited supply of these fleets causes the cost of this equipment to be a lot higher.”

The study ultimately focused on three different types of frac equipment—Tier 2 and Tier 4 dual fuel equipment and next-generation natural gas-powered equipment.

“The study was comprehensive in that included both air quality pollutants and greenhouse-gas emissions,” Allen Crum, vice president of business development for NexTier, told DUG East conference attendees.

Crum explained that cost savings for dual fuel power generation can save up to $8 million annually with a 70% natural gas replacement, while a 100% gas-powered fleet can save upwards of $10 million annually.

“Of course, not every location will have access to lean, dry field gas,” he said. “But even on CNG, the cost savings still favor natural gas-capable fleets.”

Ultimately, Cannon said, Seneca opted to deploy the Tier 4 dual fuel fleets offered by NexTier.

“Ongoing technology improvements provide room for emissions reductions and increased gas substitution,” he said. “And as an industry we continue to evolve, and technology continues to evolve. And today’s answer for us may be Tier 4, but tomorrow could very well be something else with changing operational plans.”