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Hydraulic Fracturing Techbook 2018

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42 | August 2018 | hartenergy.com By Kerr Pumps Economics of Frac Pump Fluid Ends H ow many hours do your fluid ends get?" It's a common question in the "frac patch" – and one of the most difficult to legitimately answer. Hours alone do not kill fluid ends on posi- tive-displacement frac pumps. Two primary "killers" lead to the seven widely accepted failure modes: 1. High pumping pressures – pushes metallurgy tensile strength beyond endurance limit 2. Inadequate maintenance – an age-old prob- lem for mechanical equipment The "fluid-end hours" question is a holdover from a pre-stainless steel era before ~ 2013. Until five or six years ago, 4330 carbon steel was industry standard metallurgy for fluid ends. For decades, frac crews rarely ever pumped at pressures over 5,000 to 6,000 psi. Lower pumping pressures typically kept intersecting bore stresses below carbon steel's limits. The highly corrosive nature of proppants chemically and mathematically cut carbon steel's endurance limit in half. As frac treating pressures climbed toward 10,000 psi and higher, it was only a question of "when" car- bon-steel fluid ends would crack. Internal stresses at intersecting bores increase exponentially as pumping pressures increase beyond 8,500 psi, so carbon-steel fluid end operating life became shorter and shorter. Before widespread migration to stainless steel, fluid-end life expectancy had dropped to 150-250 high-pressure pumping hours. Accurately answering the hours question requires defining "hours." Percentage of engine hours? Or transmission hours? Or accurately recorded high-pres- sure pumping hours? Many pressure pumpers once believed fluid ends pumped upwards of 80% of engine hours. Yet, closer analysis does not correlate unreal- istic pumping hour estimates to nominal pump use. High-pressure pumping hours by realistic estimations fall in the ~ 20% vicinity of engine hours. Two reliability measures that can help reduce TCO and NPT. SPONSORED CONTENT " Frac 1 CONNECT™

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