While controllers for VSD-driven pumping units have the capability today to make manually programmed intra-stroke speed changes, they do not autonomously make these decisions. This work will describe a new control algorithm that autonomously chooses polished rod velocity profiles to maximize efficiency and production while protecting pumping units and rods from overloads. The algorithm uses surface and downhole cards from the earlier stroke, generating a new polished rod velocity profile for the following stroke. In particular, the algorithm modulates ramp rates and peak velocities of a smooth ‘trapezoidal’ velocity profile. Simulations of this algorithm suggest that rod fatigue, rod buckling and load violations can be corrected, while maintaining production. Results from full-load tests will be presented to show how the algorithm morphs surface cards to fit the permissible load envelope of pumping units. Using such an algorithm, overall power consumption of rod pumping can be expected to decrease by 10-20%.
Presenters
Kalpesh Singal, Abhijit Khare, Justin Barton, Shyam Sivaramakrishnan, David Doyle, Qing Wu, Michael Honey, Darrell Stubblefield and Terry Stephenson
GE Lufkin Rod Lift Systems