Thru-Tubing Conveyed ESP Pump Replacement--Live Well Intervention

Abstract

Abstract ConocoPhillips Alaska, Inc. (CPAI) began installing Electric Submersible Pumps (ESP) on the North Slope in 1996. ConocoPhillips soon found that a frequent mode of ESP failure was pump wear caused by abrasives (sand/silt) or pump plugging (sand/scale). The high cost and long lead times associated with North Slope rig workovers drove the need to find an economical way to pull and replace worn or plugged pumps. Thru-Tubing Conveyed (TTC) electric submersible pump technology was developed by Centrilift and ConocoPhillips to address this issue. TTC technology allows electric submersible pumps to be changed out on live wells without the need to kill the well and work it over. When a TTC pump replacement is performed, the pump is pulled and replaced with slickline or coiled tubing while the tubing, seal section, motor, power cable, and down hole gauges remain in place. The pump can be replaced as many times as necessary until a failure occurs in the tubing, seal section, motor, or power cable. Centrilift and ConocoPhillips initially started with Thru-Tubing Conveyed Electric Submersible Progressive Cavity Pumps (TTCESPCP), which are capable of handling high solids production at lower rates. As well productivity increased with the shifting focus from vertical to horizontal/multilateral wells, TTC technology was adapted to centrifugal pumps to handle increased flow rates. The Thru-Tubing Conveyed Electric Submersible (centrifugal) pumps (TTCESP) are capable of handling high fluid and gas rates and moderately high solids production. CPAI and Centrilift have run TTCESPCPs for 10 years and TTCESPs for seven years. This paper discusses the positive and negative results CPAI and Centrilift have experienced with TTCESPCP (progressive cavity) and TTCESP (centrifugal) systems. Lessons learned, ESP run life statistics, and economic analyses are included.