A Novel Method For Coiled Tubing Installation

Abstract

Abstract Installation of flexible pipe for offshore developments is costly due to both the physical cost of the flexible pipe, and the expensive day rates and availability of suitable installation vessels. Considering the scarcity of flexible pipe in today's increasingly demanding and busy market, operators are seeking a cost effective solution for installing piping in a range of water depths using vessels which are readily on hand. This paper describes a novel approach to installing reeled coiled tubing, from 1inch to 5inch diameter, from the back of a small vessel in water depths from 40m up to around 1000m. The novelty of the system is the fact that the equipment design allows it to be installed on even relatively small vessels of opportunity, such as anchor handling or installation vessels, from smaller, and cheaper quayside locations. Such an approach is the ideal solution to the problem faced by operators, in that it allows the installation of cheaper, readily available coiled tubing, from cheaper and more readily available vessels. Introduction Flexible pipe technology has developed rapidly in order to meet the increasingly demanding requirements of the offshore industry. As offshore developments have progressed into deeper and more demanding environments, flexible pipe manufacturers have been pressing to provide new flexible pipe technologies suitable to the task. The natural advantages of flexible pipe over rigid pipelines make it the preferred solution for many shallow water developments, however, its convenience means that there is enormous demand for the product. Such is the market's demand for flexible pipe that flexible pipe factories are working at maximum production and long lead times and high prices are commonplace. Once produced, the pipe still needs to be installed and the available installation vessels are not only expensive, they are usually operating on long term contracts and must be booked months or years in advance. However, there is an alternative to using flexible pipe for some offshore situations. Coiled tubing is a proven technology which has largely been forgotten by the industry after the advent of flexible pipe technology. This paper shows how it is still a viable and attractive alternative to flexible pipe, and can be installed cheaply and easily from the back of small vessels of opportunity. Introduction to Coiled Tubing As long ago as 1944 engineers were faced with deploying subsea pipelines using a reliable and easily deployable design. The project in question was how to supply the allied army with fuel oil after the D-day invasion. The pipes needed to be installed in as short amount of time possible after D-day, using whatever vessels and crew were available. The solution devised by British engineers was to lay twenty three 3?? pipelines across the English channel, varying from 30 to 70miles long (48km to 113km). The pipe was made in 4000ft (1219m) sections, butt welded together, stored in spools and deployed across the English channel.