Looks Forward to HPDI Engines Using Even Less Diesel
Encana is moving to use more natural gas to produce natural gas, using methane straight from the ground where feasible and trucking in LNG where source gas doesn’t work.
A dozen of Encana’s 31 rigs are using natural gas power in some form, according to natural gas economy operations VP David Hill.
Diesel displacement with current dual fuel (some call it bi-fuel) technology ranges from 30 to 50%, Hill says. “We expect to see higher fuel displacements with OEM dual fuel systems in the range of 50 to 70%,” he adds. High pressure direct injection engines, as being developed by Caterpillar and Westport Innovations (F&F, June 6), could bring diesel displacement to better than 90%. Dedicated natural gas engines eliminate diesel altogether.
Where and when for more? “It’s very regional and geographically specific,” Hill says.
The incentive? By using natural gas in lieu of diesel, “We saved about $11 million last year on our drilling fuel costs.” There is thus little doubt that the trend will continue.
Looking to Use Gas for Fracking Too
At Encana at least, the transition to methane has thus far applied primarily to engines powering conventional drilling machinery, where it has been done for about six years, starting with the Jonah Field in Wyoming, Hill says. There, Caterpillar 3512 engines were replaced with Cat 3516 engines. Encana was able to use conditioned field gas, available at the site, and recorded savings of more than $115,000 in fuel costs for every well drilled.
And, Hill says, as low gas prices prompt the closing of some gas wells, natural gas is being used to power oil production engines too.
Looking larger, “We’re just beginning to experiment with pressure pumping,” Hill says, where more numerous and more powerful engines drive the high PPS – pressure pumping services – machinery necessary for hydraulic fracturing, or fracking. Natural gas-powered fracking is underway as a pilot project at Horn River in British Columbia. There, Caterpillar 3512 engines were modified for dual fuel (often called bi-fuel in the high horsepower community) with Altronic GTI gear allowing diesel to be burned concurrently with cleaner and more economical natural gas.
A separate natural gas-powered PPS pilot project is planned for the U.S. Rockies this year.
Issues to be addressed as E&Ps like Encana embrace natural gas for their production operations include personnel training, a loss of power which in some cases necessitates the use of larger natural gas engines than are necessary for diesel, the tendency of natural gas engines to lose more power at high altitudes, and the consistency of field gas.
LNG for Consistency
The fuel consistency issue can be solved by using liquefied natural gas – which is of course more costly as LNG is a commercial product that must be purchased and delivered. Encana began buying LNG for its production operations about a year ago, Hills says. Suppliers include Prometheus Energy, which provides both LNG fuel via tanker and vaporizers to render it usable on-site. Encana has built its own vaporizer too, and will have four in service by year-end.
“All Encana new-build rigs are going to be natural gas,” Hill said at the DoE-NREL-sponsored NGV Technology Forum in San Francisco this past October (F&F, October 31). Encana’s existing rigs? “Our goal,” he told F&F earlier this month, “is to convert as many as practical.”
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Source: Fleets & Fuels interview, follow-up and research