New Design of a Guidelineless Horizontal Tree for Deepwater ESP Wells
Authors: Olijnik L.A. , Paula M.T.R. , de Figueiredo M. Wemeck , Rutherford H. Wayne 
Published: October 2008

This paper presents the new design of a horizontal tree for deepwater installation, as a key equipment for application of Electrical Submersible Pump in Sub sea Wells.

The production from sub sea equipped with ESPS is a reality since October/94 with first installation in Campos Basin. The horizontal tree adds simplicity to work over operations expected to be two to three times more frequent when compared to natural flow or gas lifted wells,

The design and fabrication of the deepwater horizontal tree is a result of a Technological Cooperation Agreement, The design incorporates new solutions, mainly in diver leas guideline less connection of power cables and flow lines using the vertical connection system, The guideline less horizontal sub sea tree is fully prepared to be integrated on the new manifolds being designed to the Brazilian deepwater oilfields

The applications of the horizontal trees in sub sea ESP wells reduce intervention cost, increasing economical attractiveness and scenarios for the applications of this new boosting technology.

Background

The successful installation of the Petrobras' prototype in sub sea RJS 221 wI1, the first sub sea WS1lin the world to make use of ESP system. The well was put on stream in October 94 and has been producing without any failure ever since. This project was created as a part of Technological Innovation Program for Deep and Ultradeep Water. Considering the well characteristics, a 202 stage pump was installed -at2,000 meters depth designed to operate together with a 60 Hz, 100 HP, 1115V, 55A model 456 motor. The sub sea Christmas tree used was a conventional dual 4" × 2"'diver assisted tree adapted to receive the wet mate able power connector for down hole pump. Modulations at the tubing hanger and the master valve block making possible the installation:Tubing Hanger: The annuls valve was eliminated and an internal profile was prepared to assembly the wet electrical receptacle;Annuls Stab: It was adapted to allow the assembly of wet electrical connector;Master Valve Block: Annulus vertical and horizontal access was adapted to allow the electrical cable to cross the block and the vertical outlet connection;Plate of Umbilical Interface: It was adapted to allow the diver electrical connection.

Introduction

The advantages of the horizontal sub sea tree system in deepwater application motivated this &sign, a versatile equipment that permits the operation to be flexible and reduces the cost and time of installation and intervention, considering the Brazilian scenario, where there are many wells in deepwater oil fielda candi&tes for ESP system application.

The completion of the RJS 221 well showed that the use of ESP system in a sub sea tree is a viable alternative to be considered in the exploration of the oilfields. The development of suitable power transmission systems, cables, connectors, transformers and also speed divers, will increase the use of this concept in a new well.

The Completion in Ultradeepwater

In this scenarios and considering the equipment point of view, the horizontal subsea tree can accommodate required features associated with ESP, because when down hole pumps are used, the frequency of workover tends to increase,