Abstract
Shell Canada Limited produces 6-9° API bitumen from a number of multilateral horizontal ("SoakRadial") cyclic steam wells as part of its thermal recovery project at Peace River in Alberta, Canada. These wells typically utilize a conventional beam lift pumping system with a variable frequency drive for speed control. In seeking ways to optimize the artificial lift system, Shell Canada initiated, in 1998, a controlled test of a mechanical long-stroke pumping unit as a possible alternative to conventional pump jacks. The objective of the test was to evaluate the unit for operating reliability, its ability to lift available production, lifting cost (power consumption) and frequency of maintenance. In addition, the test included a pump-off controller system on one long-stroke and one conventional pumpjack, enabling close monitoring of well conditions and differences in operating parameters.
Variations in productivity due to the cyclic nature of the steam soak operation of these wells present unique challenges to conventional pumping systems. Ability to closely match pumping rates to well inflow is expected to result in lower operating and maintenance costs, a feature that long-stroke units were expected to offer. Field tests have in fact shown that these units can increase daily production rates through better pump efficiencies and longer stroke lengths, while reducing the amount of power consumed and thus operating cost. Other benefits include reduced wear in downhole pump components and comparable equipment reliability to conventional pumpjacks. While some issues arose around servicing of wells equipped with the long-stroke units, changes to wellhead and surface facility design on future wells is expected to overcome most of these.
