Coiled-Tubing-Deployed Electric Submersible Pumping System

Abstract

ABSTRACT The results of what is believed to be the first CT deployed Electric Submersible Pump (ESP) will be presented in this paper. Coiled tubing (CT) has long been used to accommodate many workover operations where a drilling or workover rig is either not available or is cost prohibitive. In many areas, the cost or lack of available rigs to service an ESP has been a limiting factor when considering ESPS for artificial lift. This field example shows the effectiveness of a coiled tubing unit for installing an ESP. The technical considerations addressed when designing a completion are discussed as they relate to a specific field installation. The installation proves the viability of using CT units as a means to utilize ESPS for artificial lift. INTRODUCTION CT has been used throughout the world for a variety of workover operations since its introduction in the 1960s. CT is used extensively for a variety of purposes including: logging highly deviated wells, well stimulation, cementing, perforating, drilling and cleaning out fill material. The same economics which drive the use of CT for the above operations, make it an attractive method for deploying ESPS where the cost of a workover rig is prohibitive.CT is a continuous length of tubing coiled onto a large reel which is driven by a portable control unit. An injector feeds the tubing into the well and is also used to pull the tubing out of the well (Fig. 1). The tubing is fed through well control equipment and into the well. CT is currently available in a variety of sizes ranging from 0.75 inch outside diameter (0. D.) (19.1 mm) to 3-1/2 inch O.D. (88.9 mm). Also, yield strengths from 70,000 psi (483 MPa) to 100,000 psi (689 MPa) are available. Most CT is similar to standard N-80 grades of tubing and may be considered for use in environments suitable for N-80 tubing. If extreme corrosion resistance is a requirement for a given completion, other materials such as titanium exist to suit almost any downhole environment. The ESP system comprises a downhole pump, electric power cable and surface electrical controls. In a typical application, the downhole pump is suspended on a tubing string hung in the wellhead and submerged in the well fluid (Fig. 2). The ESP has the broadest range of any artificial lift method. Pumps are available from 100 bbl/day (18.4 m3/day) up to 95,000 bbl/day (15,100 m3/day). ESPS can produce from depths up to 15,000 feet (4570 meters) in 4- 1/2 inch (114.3 mm) and larger casings. Systems are available to perform in wells with bottom hole temperatures up to 450 deg F (232 deg C). Because both the CT technology and the ESP technology already existed, only the details of a work window for the purposes of assembling and running ESP equipment had to be designed and built. Also, a procedure for using ESPS and CT together had to be formulated.