Subsea Wireline: Two Years of Practical Experience
Authors: Pollock R.A. 
Published: October 2008

Historically, remedial wireline operations on subsea completions have required the use of semisubmersible drilling rigs, or, provided the well was suitably equipped, the use of Through Flowline (TFL).

To date 13 wells in 5 different fields in the UK Sector of the North Sea have been successfully entered utilising a purpose built subsea wireline lubricator (SWL) deployed from both a dynamically positioned monohulled vessel and a Floating Production Facility.

The SWL is designed to be deployed from a suitably equipped vessel, can be run on either 2 or 4 guidelines with or without diver assistance utilising ROV support. The complete SWL is designed to be run in one piece and remains connected to the wellhead for the duration of the work. In the event of an emergency disconnection, the guide wires and umbilicals are remotely disconnected and recovered to surface. The SWL is designed to remain connected to the wellhead during a 50 year North Sea storm. During normal wireline operations to change wireline tool strings it is only necessary to hydraulically unlatch the inner mandrel from the stuffing box and recover it and the tool string to surface.

This paper describes the actual field experiences gained over the past two years in the UK Sector of the North Sea in the deployment and operations of a subsea wireline lubricator (SWL) system. The paper will also describe the application of the field proven Cameo Liquid Seal System to the SWL for the effective control of mono conductor and braided cable operations subsea.

Significant cost savings can be accomplished using a SWL system that is highly mobile, is deployed from state of the art dynamically positioned vessels and is field proven.

INTRODUCTION

With the proliferation of subsea completions over the past few years and the increasing tendency of marginal fields to be produced subsea for economic, environmental and safety reasons a reliable and simple method of re-entry for these wells is required. This paper briefly details the history, the system, the operations in 1988/89 and future developments of the Camco Subsea Wireline Lubricator (SWL).

HISTORY

In 1985 Cameo Ltd entered discussions with a major North Sea operator to develop an improved version of subsea lubricator that was being utilised from their floating production platform. The modifications were necessary to enable the SWL to be deployed from a dynamically positioned support vessel as well as a fixed semi-submersible drilling rig.

Negotiations were completed in 1987 and a License agreement was concluded allowing production of a subsea lubricator to commence. A complete redesign of the system was required as the lubricator would now be required to work on many different wellheads and not just on a particular wellhead as in the case of the original template. Design review and certification of the equipment to establish its compliance to current UK and Norwegian Regulations was performed by a competent certification authority in Aberdeen.

On completion of manufacture the component items were then shipped to Aberdeen for final assembly and testing.