18 March 2014
18 March 2014
Victrex PEEK polymer in composites is helping the oil & gas industry to successfully surmount the challenge of the difficult operating conditions it now encounters.
According to Victrex, the latest production methods in the oil & gas industry are placing increasingly severe levels of stress on equipment. The production tools are required to last anywhere from ten to twenty years in extreme operating conditions that include higher temperatures and pressures. In addition, it explains that the latest techniques such as measurement while drilling (MWD), logging while drilling (LWD), and wireline systems can involve critical electronic data transmission so the reliability of the tooling is imperative.
Victrex states that its PEEK polymer is proving to be capable of answering these new challenges. It says case in point is Victrex PEEK 450G, which exceeds the NORSOK M710 specification with an H2S concentration ten times that required for compliance with the standard. The thermoplastic also demonstrates superior resistance to harsh and corrosive chemicals which are often responsible for production delays.
Victrex explains that, going forward, unconventional drilling sites that require the use of high-performance antenna and logging sleeves will only serve to emphasize the need to use Victrex PEEK-based composite materials. It says the many advantages of these composites over metals include high strength, stiffness and reduced weight. Victrex states that its PEEK-based composites typically weigh 40% less than aluminium, 55% less than titanium, and 70% less than steel. It claims the immediate benefits are easier installation and faster, more efficient operation, as well as low thermal expansion, which can be one sixth that of steel. Together with the polymer's overall dimensional stability, this expansion rate enables tighter tolerances that support precision manufacturing. In addition, the composites can combine high electrical resistivity with low electromagnetic interference (EMI) making them suitable for well logging tools that require composite structures reinforced with fibre. Thermoplastic composites have proven to be more durable in high pressure/high temperature (HP/HT) applications or wherever high chemical resistance is required compared to thermosets.
The AFP technology, available from Automated Dynamics, is described as enabling composites to be built layer by layer in an automated process. This has numerous advantages over curing by autoclave and - with the addition of a laser heating capability - enables up to a ten times improvement in throughput in certain applications.
According to Brett Kimball of Automated Dynamics, "Demanding downhole applications often require continuous fibre composites made from Victrex PEEK predominantly because of their higher modulus and strength when compared to short fibre composites. These applications include antenna shields for various measurement techniques used with LWD tools, electrical and structural isolators (gap subs) on M/LWD (measurement/logging while drilling) tools, and housings and logging sleeves for wireline resistivity tools."
Victrex states another advantage of the PEEK-based composites is their hydrolytic stability with moisture absorption limited to about 0.2%. Thermosets, in contrast, typically absorb 2% moisture, precipitating dimensional instability and cracking. Thermoplastic composites will also support metal-to-composite interfacing. Automated Dynamics has also successfully used PEEK-based APTIV films as a joining technology for numerous applications.
The properties and manufacturability of Victrex PEEK-based composites enable their implementation in numerous downhole and subsea applications. Further development of PEEK-based materials is expected to keep pace with the increasingly severe demands of oil & gas environments.
Photo courtesy of Victrex