Optimization of Hydraulic Horsepower to Reduce Total Fuel Cost

Abstract During hydraulic fracturing operations, the diesel fuel consumed by equipment is a major expenditure in an operator's completion program. More specifically, the diesel fuel consumed by a hydraulic fracturing fleet can account for nearly 20% of consumable costs on an average single well field ticket. By efficiently displacing diesel fuel with natural gas, an operator can reduce the cost of their completions program. This reduction in diesel fuel consumed also leads to lower carbon emissions, less pad traffic, and could ultimately result in less motor vehicle accidents and environmental issues. A completion services company conducted a study to decrease the total fuel consumption, diesel fuel and natural gas, of a hydraulic fracturing fleet by optimizing the operating conditions of the pumping units. Expected results of this study included the determination of an operating range for both hydraulic horsepower and engine speed that would lead to the goal of decreasing total fuel consumption. Phase one of the study began with collecting fuel consumption and hydraulic horsepower levels of a single high pressure pumping unit on a per treatment stage basis. Multiple pumping units were selected and individually tested during this phase. The units were selected based on engine hours, transmission, and pump system. All units in the fleet were powered by a Tier-II 2500HP Dual Fuel engine. The diesel fuel and natural gas consumed by each test pump and the frac fleet during both phases were recorded using four separate Coriolis meters per stage. The diesel and natural gas supply to the entire frac fleet was measured, with an additional measurement taken for the single unit downstream of the fleet meters. Results from the study showed that by reducing engine speed from 1950 RPM down to 1850 RPM, a decrease in fuel consumption per hour and an increase in engine efficiency was achieved.