Paper: Power Savings Load Reductions On Sucker Rod Pumping Wells

In 1985, a silicon-controlled rectifier (SCR) device was installed on a sucker rod pumping well in the North Hobbs Unit, New Mexico, to eliminate a potentially severe structural shaking on unit start-up. On the basis of limited tests on this unit that indicated possible power savings and load reductions, a joint Shell-MagneTek test program was carried out in 1988 on seven pumping wells in West Texas and near Ventura, California. The SCR device was used to turn the motor off for one or two intervals during each pumping stroke. The motor was turned off for as much as 60 percent of the time in some of the tests. Tests were conducted on conventional and Mark II units and on NEMA "D" and ultra-high slip motors. Using the SCR device reduced rod loads and peak gearbox torque, or power consumption, by 5 to 15 percent on most of the wells tested. If the power generated during the stroke was ignored, power reductions were 10 to 25 percent. However, we were unable to achieve the maximum rod loads/gearbox torque reduction and maximum reduction of power consumption using the same SCR cycle. On the basis of the initial tests, a microprocessor controlled prototype unit is being designed and tested. The controller has four operating modes to a) minimize energy consumption; b) minimize rod/gear box loading; c) maximize pumping efficiency, or; d) improve overall performance by optimizing the above modes.