JIP Status Report: Advanced Spoolable Composites for Offshore Applications
Authors: Quigley Peter , Stringfellow W.D. , Fowler S. Harnpton , Nolet Stephen C. 
Published: October 2008

Flexible piping systems are critical elements in the design and operation of floating systems for offshore oil and gas production. Applications are "static" or "dynamic." staticapplications involve the use of flexible pipe to simplify design or installation where there is no, or, little, relative movement between supply and delivery points. Dynamic applications involve relative motion between supply and delivery points. These applications usual involve an offshore floating production system.

Dynamic piping is currently provided by special designs using steel, titanium, or flexible pipe systems. Each system has its strengths and weaknesses. The forces that drive a particular design strategy are weight, strength (pressure and tensile), collapse resistance and corrosion resistance, operating and component costs.

As operations move into deeper water the performance specification for flexible piping systems are becoming more severe. Future design conditions are expected to include:Operating pressures to 690 bar (10,000 psi)Temperatures to 145°C (300°F)Depths exceeding 1,500 meters (4,920 ft)Extremely sour production fluids

The importance of these systems is evidenced by industry activity. There are a number of joint industry projects (JIP) and manufacturer-funded research programs to develop lightweight, high strength flexible pipes, or riser systems. The driving force in these developments are weight reduction, enhanced corrosion resistance and means for predicting /monitoring fatigue life of the product. None of the programs currently underway take advantage of the full potential of an emerging technology such as that offered be advanced composite spoolable tubular.

This paper will discuss the progress of a JIP m Identifying applications and design specifications, and test results for qualifying spoolable non-metallic structures that may offer nabling technical and cost advantages as replacements forflexible pipe in offshore applications.

Introduction

Conoco Inc. began to develop high performance, spoolable composite pipe technology in a program that started in 1988. The original focus was on corrosion-resistant water injectionlines and later evolved to a J.5-in. OD composite coiled tubing service string1. The development effort led to a composite tube design formed by surrounding a thermoplastic liner with a high strength fiber and epoxy matrix structure. The fibers utilized include glass, carbon and aramid. The advantage of a composite spoolable pipe over steel pipe is that it can be "engineered" for particular applications to take advantage of the composite's enabling attributes. These attributes includecorrosion resistance, high strength to weight ratios, high working pressure capability, excellent cyclic fatigue resistance and low material density. In fact, the current composite tubing designs weigh in at 25 to 33% the weight of a like OD steel tube in air and are 14% the weight of steel in water. This obvious advantage allows longer and larger strings of composite tubing to be handled by coiled tubingunits of lower pull capabilities or lifted onto offshore platforms with smaller crane capabilities2.