Halliburton, Apache Corp. and Caterpillar have developed a dual-fuel technology for using natural gas and diesel to operate pumping equipment used in hydraulic fracturing (fracking) at oil and gas well sites.

The companies are calling the effort using 12 pumps totaling 24,000 hp the largest-scale dual-fuel project ever put together in the oil/gas sector. Caterpillar developed the engine dual-fuel kit that makes it possible.

Halliburton developed a technical solution for converting the pumping equipment used at a typical large-scale fracturing spread to a dual-fuel system that includes natural gas. Halliburton and its supplier, Caterpillar, then teamed up to convert the heavy equipment-maker’s Q-10 pumps to dual fuel with technology that can handle both compressed natural gas (CNG) or liquefied natural gas (LNG). Caterpillar adapted its proprietary dynamic gas blending engine technology to power Halliburton’s pumps.

Lower-priced natural gas was part of the incentive. According to Apache CEO G. Steven Farris, in 2012 the industry used more than 700 million gallons of diesel fuel to pump sand and water during fracking stimulation at an average cost of $3.40/gallon for diesel. That amounts to an annual diesel bill of $2.38 billion for fracking.

“By converting the process to use field gas, fuel costs would be reduced by approximately 70%, or by $1.67 billion,” Apache said.