Abstract

An offshore well located in Eugene Island Block 384 in the Gulf of Mexico loaded up and ceased flowing, This behavior was attributed to an unstable flow regime caused by declining gas production in the field and by the large flow area of the 4 1/2-in. completion string. To re-establish stable flow, a smaller size production tubing was required to decrease the flow area and thereby increase gas velocities. Because of the declining production, mobilizing a workover rig to perform a recompletion was considered uneconomical. The well was evaluated for installation of a 2 3/8-in. coiled-tubing production string with packer, gas lift mandrel, landing nipples, and subsurface safety valve (SSSV) completion equipment. A coiled-tubing unit was mobilized, and the 2 3/8-in. coiled-tubing recompletion was successfully performed inside the existing 4 1/2-in. completion. The well was returned to stable production at approximately 40% of the cost of a workover-rig operation. This paper discusses the successful recompletion job design and field installation on the subject well and addresses the economic viability of using large-diameter coiled tubing as a permanent completion in offshore applications.

Introduction

A deepwater offshore well in Eugene Island Block 384 of the Gulf of Mexico was located in a declining gas field. The increasing water influx into the large flow area of the 4 1/2-in. completion string caused the well to load up and to cease flowing. As an economical solution to maintaining stable production, the operator sought to install a 2 3/8-in. siphon or production string in the existing 4 1/2-in. completion string. A workover rig was rejected because the high costs of deepwater mobilization and demobilization could not be justified in light of the declining production. The operator contacted a service company to investigate the possibility of a coiled-tubing recompletion.

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