Case History in Coiled Tubing Pipeline
Authors: Kenawy Farouk A. , Ellaithy Wael F. 
Published: October 2008

Coiled tubing pipeline is a rapidly growing technology. Utilization of coiled tubing as pipelines is new application to an existing technology. Until recently, service companies primarily used the coiled tubing for coiled tubing workovers. As the technology expanded the industry began using coiled tubing for other applications such as drilling, coring, logging, well clean out operations and artificial lift. As the tubing mills began production larger sizes, it became possible to consider using coiled tubing as pipelines. In 1997 approximately 1.5 Million Feet of coiled tubing pipelines installed worldwide.

The Gulf of Suez Petroleum Company (Gupco) as a joint venture between Egyptian General Petroleum Corporation and Amoco is a role model of the implementation of coiled tubing pipeline technology. Gupco embarked her first 3.5" coiled tubing pipeline in 1994. Subsequently Gupco has taken a leading role in the application of coiled pipe technology with the 1996 installations using the first production of 4.5 inch coiled pipe, one of which is a record setting 62,000 FT. high pressure water supply line. Since 1994 Gupco installed approximately 250,000 FT of coiled tubing submarine pipelines for different applications.

This paper presents Gupco case history for the installation of 1 3/4", 3 1/2" & 4 1/2" of coiled tubing pipelines. It will present the different pipeline laying arrangements ranging from the simple supply boat combination to utilization of a hook up barges, then dynamically positioned vessels. Advantages and limitations of each installation arrangements will be presented based on the experience of laying 1/4 million feet of coiled tubing pipelines in the Gulf of Suez. Also, it will present the continuous effort to improve laying arrangements and equipment.

Paper will conclude with the challenge encounter the industry of the coiled tubing pipelines to remain the cost-effective challenge and to expand the business market share.

History of Development

While the history of reeled steel pipe can be traced toapplications at the time of World War II, coiled tubing (CT) has been used in the oil and gas industry primarily in well servicing work. Dating from the mid-1960's, the progressive development of both the material capability and the field handling equipment has resulted in significant growth for the downhole CT industry.

As late as 1990, the largest CT that was available on the market had an outside diameter of only 1-3/4" (44.5mm). Since that time, continued developments by the CT manufacturers have pushed the available size range to 4-1/2" OD (114.3mm) with a maximum nominal wall thickness of 0.300" (7.62mm). This expanded range of diameter and wall thickness is one of the primary developments that makes possible the application of continuously milled, reeled pipelines.

Fabrication

The manufacturing of coiled tubing pipelines takes place in essentially three steps which are further detailed below:Assembly of steel strip required for the reel of tube.Production of the reel of tube from the assembled steelstrip.Application of the external corrosion coating.

The raw material utilized in the production of CT forpipeline applications consists of high strength, low alloy carbon steel that is continuously cast and hot rolled to the final required thickness. Various grades of material are available with final product characteristics ranging from the equivalent of API 5L X-52 through an X-80 equivalent being routinely applied. Due to various manufacturing and handling limitations, the length of the steel strips, as delivered to t