Abstract

BP Exploration and Nowcam Services have recompleted a well in the Western Operating Area (WOA) of the Prudhoe Bay Unit with a spoolable coiled tubing gas lifted completion. This completion is unique in that gas lift valves are inside the coiled tubing. Their design allows them to bend as the coil is run into the well, and prevents damage to the valve or the coiled tubing. Advantages of this system are low cost (68% below average rig workover cost) and the ability to run and pull the gas lift valves without stopping to install or remove them.

Actual running time for this re-completion was about 18 hours, with 6 of those hours needed to install the Subsurface Safety Valve (SSSV) landing nipple and 4 hours down time due to the Coiled Tubing (CT) injector chains icing up from blowing snow. After completion, the well produced 1060 bpd fluid (320 bopd) at a 1.5 mmscf/d lift gas rate. Current gross production is 750 bpd (260 bopd net) with a gas lift rate of 1.5 mmscf/d.

This re-completion is just the first step in the development of a completely spoolable coiled tubing completion system. While this job required cutting the coiled tubing to install a landing nipple for a SSSV, it is an objective to have in place by year end a spoolable SSSV system and any other necessary equipment needed to achieve a completely "slick" completion. Once achieved, it will be possible to run this system in a well without having to stop to cut the coil and install equipment.

Introduction

Prudhoe Bay wells are on decline. More wells require smaller tubing to ensure continuous, stable production. After several years of production, wells may also have corroded tubing that eventually develop leaks. Until now, viable solutions to these problems included electric line or coiled tubing conveyed tubing patches and straddles, and rig workovers to downsize the tubing, sidetrack to a new location, or plug and abandon the well.

An alternative now exists using the spoolable coiled tubing gas lifted completion system. Costing 60 - 70% less than a conventional rig workover, a well can have a new, and smaller, gas lifted completion.

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