Glass-Reinforced Epoxy Effective Alternative to Alloys in Gas Wells
Authors: Feder Judy 
Published: August 2020

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper IPTC 19696, “The Application of a Fiberglass Liner in Well Tubing as a Cost-Effective Material Option in High-Velocity Production Wells,” by Carmen Repetto, Simone Gorini, and Giacomo Andrea Nutricato, Eni, et al., prepared for the 2020 International Petroleum Technology Conference, Dhahran, Saudi Arabia, 13-15 January. The paper has not been peer reviewed. Copyright 2020 International Petroleum Technology Conference. Reproduced by permission.

The complete paper describes an operator’s experience in confirming glass fiber-reinforced epoxy (GRE) as an effective alternative to high-grade corrosion-resistant alloys (CRA) to extend tubing life in high-velocity gas wells. Laboratory testing and applications in several fields, both on and offshore, and in oil-production and water-injection wells and surface-gathering lines, demonstrate that, when used within the operating limits, GRE can extend tubing life and provide life-cycle cost savings.

GRE

The material has been intensively tested in the past to determine characteristics and capabilities. Mechanical properties, fatigue resistance, chemical compatibilities, connection properties, and abrasion trials have been proved by specific laboratory tests and field trials, demonstrating that GRE can be applied inside production tubing strings. API RP15CLT, first issued in 2007, provides guidelines for the design, manufacture, qualification, and application of composite-lined carbon-steel downhole tubing in the handling and transport of multiphase fluids, hydrocarbon gases, hydrocarbon liquids, and water.

Carbon steel guarantees the system’s mechanical resistance, and the internal GRE liner ensures corrosion resistance. GRE provides outstanding corrosion resistance, even in very aggressive environments.

For oil-well applications, the system consists of a GRE resin composite liner inserted inside a low-alloy carbon steel tubing with a cement grout (Fig. 1). The grout transfers pressure directly to the steel tubing even if there is little or no bonding between liner, grout, and metal.

The end of the liner is protected from mechanical damage by a GRE end cap (flare) or a T-end flange. A polymeric corrosion barrier ring usually provides the continuity of the corrosion barrier across the coupling between two adjacent flares. The lining is lightweight, adding no more than 13% of the weight of the steel pipes and eliminating the need for additional lifting equipment.

The operator has been involved in the development of deepwater gas fields with high production rates and sour environments. On the basis of corrosion assessments performed on actual field conditions, CRA (high nickel content) material was selected as most suitable for the production tubing string. Following positive experiences with the installation of GRE, the company decided to evaluate its performance in potentially high-erosion conditions, aiming to find an alternative material to high-grade CRA for installation in high-velocity gas wells that would reduce cost and delivery time. The GRE liner was selected as a cost-effective alternative to high-alloy materials starting from 2005, when GRE was successful in reducing onshore workover costs and extending the life of carbon-steel tubing in oil producer wells with high carbon dioxide and water cut, to recent installations offshore Norway in water injection wells with highly corrosive injection fluids.