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Natural Gas Engines Replace Diesel On Drilling Rigs
April 4, 2013

Houston, Texas

With diesel prices remaining high, Antero Resources and Patterson-UTI Drilling were seeking a viable option to reduce fuel costs, a major expense when operating drilling rigs. That's when the companies considered an innovative solution: the Waukesha VHP L7044GSI. Offered by GE's Waukesha gas engines and Waukesha-Pearce Industries, the rich-burn engine is 100% natural-gas-fired, reducing fuel costs while also meeting stringent state and federal mobile emissions guidelines.


The four companies recently finalized the first installation of three L7044GSIs with a well completion in Harrison County, W. Va., and plans are in the works to replace diesel engines powering drilling rigs in multiple other locations.

"The low cost nature of switching to natural gas-fired rigs versus the conventional diesel-fired rigs and the intense focus on reduced emissions make the Series Four 7044 a terrific choice. When considering investment in new equipment or improvements to existing equipment, reduced emissions and cost-saving solutions have been identified by Antero as a major area of opportunity," said Kevin Kilstrom, vice president of Production for Antero Resources. "GE and WPI worked with us to identify a solution and all indications suggest this engine, with its fuel gas tolerance and no load bank requirements, provide those solutions and offer operational benefits including reduced fuel truck traffic at the drill site through consumption of a local Appalachian fuel source."

"The L7044GSI can be easily exchanged with existing rig power generation drivers, almost to the point that they're 'plug and play,' as we've seen in this project.  And it offers great cost advantages of natural gas versus diesel and dual-fuel, with natural gas available at less than half the price of diesel. Plus, you can reduce diesel transportation costs and potential liability because the engine can run on a much greater variation of readily available fuel sources, using everything from dry field gas to pipeline gas, including LNG and propane," added Fred Stow, director of sales for WPI.

Maintenance schedule helps reduce total cost of ownership

The L7044GSI gas engines also boast a reduced maintenance schedule versus other spark ignited and diesel engines, increasing its appeal to drill operators. "Compared to other spark-ignited lean-burn engines, rich-burn engines operate at lower cylinder pressures, providing longer operational times between oil changes, top-end overhauls and complete overhauls. This extends the service life of the engine to provide a higher rate of return on investment for the operational horsepower needs," said Brian White, president of GE's Waukesha gas engines.

Fuel flexibility also reduces emissions

With performance ratings at altitudes up to 8,000 feet with no de-rate, the L7044GSI uses Non-Selective Catalyst Reduction (NSCR) technology — commonly referred to as a Three Way Catalyst (TWC) — achieving NOx, CO2 and VOC values much lower than lean-burn engines, which typically must be equipped with an expensive Selective Catalysis System (SCS) to meet emissions requirements. As NOx permitting requirements approach 0.5g/BHP/hour and below, rich-burn engines equipped with TWCs operate more cost effectively and provide greater return on investment.

While CO2 is the most significant greenhouse gas addressed globally, methane has 21 times the effect on the atmosphere, an advantage for rich-burn engines as they produce substantially less methane than other options. And since the EPA requires the inclusion of both CO2 and methane in carbon calculations, rich-burn engines deliver a better greenhouse gas profile. Further, formaldehyde emissions (the most significant of all the hazardous air pollutants emitted by engines) can be 10% less when using a rich-burn engine.

"We firmly believe the natural gas solution will give drilling contractors a reason to consider the L7044GSI for a number of reasons," said WPI's Stow. "It operates with a wide margin for both knock and misfire and has a high tolerance for fuel composition. At lower NOx levels, lean-burn engines operate in an increasingly narrow window, and that limits fuel flexibility and makes them more sensitive to site conditions. This is an engine that has the power to change an industry."

If you have any questions or comments regarding this article please contact Aubrey Hilliard at