Field Experience with Composite Coiled Tubing

Abstract

Composite Coiled Tubing (CCT) has been field tested on a number of applications with generally good results. This paper will summarize these field experiences and how the tubing has been improved from early versions to the latest product. Introduction Over the past seven years Fiberspar has developed continuous spoolable composite tubing technology, building upon work done by Conoco in the previous five years. Early development centered on downhole applications as a low fatigue and corrosion resistant alternative to steel coil tubing, but after this initial development period, market pull re-focused the technology on surface applications. As a result, the technology was first commercialized in 1999 as LinePipe, for surface gathering and injection applications. Almost two million feet has now been manufactured and installed successfully in these surface applications, mostly in North America. The technology has proven to be a reliable and cost effective alternative particularly for any corrosive application. It has also enabled innovative installation techniques, which are rapid, safe and require little manpower, and is setting new standards in installation speed and reliability for the small diameter pipe construction industry. As operating companies realize the promised benefits in installation and performance, the momentum in this area is gathering and composite spooled tubing has become a realistic alternative to existing corrosion resistant solutions such as lined steel, and discrete length reinforced fiberglass pipe8. The range of applications is growing as the technology matures and develops. The technology, and in particular the development of the manufacturing processes, has greatly benefited from this commercial success and volume production. When the technology was first developed, many industry experts believed that the biggest risk to establishing a commercial rather than a technical success would be the ability to manufacture long continuous lengths to a consistent high quality standard. Now, product is routinely made in lengths of 18,000 feet, and occasionally longer, in a highly automated, 24 hour, continuous process. The process is not labor intensive, and is very robust. Length limitations are a result of the product packaging rather than process reliability. While not the top priority over the last three years, some development of the technology for downhole applications has continued. The surface applications are reaching a point of maturity, which will now allow some additional focus on the downhole market. Although the basic technology for use in surface and downhole applications is broadly similar, several changes have been implemented to make the pipe suitable for these applications. Field testing as well as lab testing was undertaken and this paper will review some of these field experiences, lessons learned and further improvements which were made as a result. It will also briefly cover the planned strategy and focus areas for expanding the use of the technology for downhole applications, and some current development, which will further extend the capabilities and applications of Composite Coiled Tubing. Tube Design The basic design of the spoolable composite tubing consists of an internal fluid barrier- normally a thermoplastic extrusion, on which the reinforcement is wound in a continuous process. (See Figure 1).