As reported previously, a series of oil field pumping units has been developed with power outputs of 125, 250, 500, and 1000 kW, designed for injecting working fluids in cementing operations in oil and gas wells, hydraulic fracturing of formations, washing out sand plugs, and other production operations. The units are designed for the use of three-plunger pumps with individual power outputs of 125 or 500 kW. In the 250- and 1000-kW units, two such pumps are used. The 1000-kW pumping unit serves mainly for deep-penetration hydraulic fracturing of formations, and also for fracturing deep formations. The hydraulic fracturing process does not require the use of units with two pumps; this has been demonstrated by experience, both here and in other countries. All units intended for use in hydraulic fracturing are built with a single pump, transmission, and drive. Pumping units for well cementing must have two pumps that will give a high delivery rate. At the start of the operation, a single pump can be used to feed water into the cement mixer, with the second pump used to transfer the cement slurry to the well. Then both pumps are connected to the slurry injection line. The operation ofmore » these pumps is described.« less