Through-Tubing-Conveyed ESP Replacement - Live Well Intervention

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 116822, "Thru- Tubing Conveyed ESP Pump Replacement - Live-Well Intervention," by Walter Dinkins, SPE, and Steve Tetzlaff, Baker Hughes; John C. Patterson, SPE, Hai Hunt, SPE, Peter Nezaticky, SPE, and James Rogers, SPE, ConocoPhillips; and Bret Chambers, BP plc, originally prepared for the 2008 SPE Annual Technical Conference and Exhibition, Denver, 21-24 September. The paper has not been peer reviewed. Through-tubing-conveyed (TTC) electrical-submersible-pump (ESP) technology was developed to address the high cost and long lead times associated with North Slope rig workovers to pull and replace worn or plugged pumps. TTC technology allows ESPs to be changed in 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 downhole gauges remain in place. Introduction The first TTC systems were installed in West Sak development wells on the North Slope of Alaska in 1998. The first systems were TTC electrical submersible progressing-cavity pumps (TTCESPCPs). In 2001, TTC technology was expanded to include centrifugal pumps to achieve higher production rates. The centrifugal TTC pumps were given the designation TTCESP. TTCESP lift systems continue to be the preferred equipment for the West Sak field. TTC technology is particularly applicable in wells with high solids production in which the pump is the primary failure mode. TTC technology also provides a means to upsize, downsize, or add pump components such as rotary gas separators without rig intervention on live wells. TTCESPCP and TTCESP Components From bottom to top, the rig-deployed (tubing-conveyed) components of a TTCESPCP consists of motor centralizer, motor, gear-reduction unit, tandem seal sections, and TTC crossover. A power cable is clamped to the outside of the tubing and is run from the motor to surface, and a separate instrument wire is run for a downhole gauge located in a side-pocket mandrel above the ESP assembly. The TTC crossover (Fig. 1) is what allows pumps to be pulled while the motor, gear-reduction unit, seal section, tubing, instrument wire, and power cable are left downhole. The slickline-deployed TTC components consist of a pump assembly, a packoff assembly, and a slipstop. The pump assembly consists of a pump "eye" (Fig. 2), which couples the pump to the TTC crossover, and pump and discharge assembly, which includes a centralizer and fishing neck.