Wireline Retrievable Electric Submersible Pump: Innovative and Valuable Completion for Offshore Fields
Authors: Dieuzeide Thomas , Bemba Alain P. , Kusuma Dadik H. , Anderson Graham 
Published: May 2016

All of Total E&P Congo's production comes from offshore wells and the majority of these producers use secondary lift, mainly gas-lift and ESP (Electrical Submersible Pump). The efficiency of ESP and high delta pressure operation means that all new field developments use them along with a number of gas-lift conversions. One disadvantage of using ESP is the need for frequent intervention which, when coupled with a high work over cost and subsequent deferred production, both due to dependence on available work-over vessels in the region, can lead to exceedingly high operating costs.

Moving away from this rig dependency towards a lighter operation would mitigate these drawbacks and greatly reduce the operation cost of the ESP systems deployment. Those changes are possible with the Wire Line Retrievable ESP (WR-ESP) technology.

An initial work over is to set permanent completion elements. When the WR-ESP is retrieved, the tubing and the ESP power cable stay in place (permanent completion). The WR-ESP technology provides full bore access below ESP, short and light BHA, and uses permanent magnet motor (PMM) to increase the efficiency. Well screening for the pilot installation were done for Total E&P Congo wells. The selected candidate (Field A well) allows a simple and robust completion with little operation complexity. High safety standards are guaranteed during production and also during future well intervention. The use of slick line unit for ESP change-out is the key of this technology due to its flexibility, rapid mob-demobilization, and small operational cost compared to offshore pulling unit or rig.

This bold way of deploying ESP is possible due to two main technical innovations:Retrievability: a Wet connector which allows the down hole connection between Wire Line ESP motor and permanent power cable (outside tubing)Slick Line feasibility: a PMM motor which is lighter and shorter than classical ESP motors

The WR-ESP technology will therefore reduce OPEX, increase the wells reserve (WR-ESP change outs are still economical at lower oil rate compared to classical ESP deployment), increase well uptime, reduce production deferment and maybe change completely the new field development schemes (such as the challenging Ouganda fields). A SIT (System Integration Test) prior to the field deployment is about to be done in October 2013 on a Djeno water well. The work over on WELL1 (selected well) is planned in January 2014.

Introduction

Total E&P Congo (TEPC) is at TOTAL affiliate located in western Africa. Its production comes 100% from offshore fields. Most of the producing wells are activated by artificial lift. The affiliate developments have initially been on gas lift production. With production and pressure decline, a new artificial lift method has been looked for. The ESP technology was the preferred solution. This artificial lift technology is tubing retrievable and needs a work over with a heavy intervention unit. Since the introduction of ESP technology, the new developments are oriented to that technology. At the same time the brown fields see gas lift to ESP conversions, when feasible. The main advantage of using ESP production is that it allows a higher draw down and therefore a higher flow rate compared to GL.