The markets: Oil and gas (2017)

Composites have long been recognized as an enabling technology in deepwater drilling scenarios. Their most recent role is being played out in expanding practice of hydraulic fracturing.

The salt in seawater makes its oceans Earth’s largest naturally occurring corrosive environment. Compound that with man-made multipliers, such as high-temperatures and pressures and the host of aggressive chemicals, solvents and other fluids required to operate an offshore oil rig, and that’s a recipe for conditions that, over time, can be deleterious to almost any material, but especially hostile to metals.

Not surprisingly, inherently corrosion-resistant composite materials have increasingly been used to mold previously metal parts deployed in a host of offshore drilling platform applications. These include non-load-bearing topside platform components, such as fire-water mains, high- and low-pressure tubing, processing vessels and tanks, fire-blast panels, gratings and handrails, as well as newer subsea structures, such as carbon rod umbilicals and components for protecting wellheads, manifolds and other equipment related to subsea processing. Composites also are making tentative inroads into higher volume, more demanding offshore oil and gas applications, such as the systems of pipes with which producers explore for oil, find it and eventually bring it up from the wellhead to the surface. Although many are still in development — a process that includes a lengthy and rigorous qualification phase — the impetus behind this R&D is seen by most everyone in the industry as significant. The question is not if but when offshore oil operators will be compelled to make greater use of lightweight composites in structural undersea pipelines. This question is all the more critical as exploration companies develop subsea oil fields at greater distances from shore and do so at unprecedented depths. In 2003 in the Gulf of Mexico, for example, just 35% of production was from wells at depths of 300m. By 2015 that figure was 95%. More to the point, more than 20% of Gulf wells are now at depths greater than 2000m. At these depths, traditional steel pipe systems pose serious logistical problems and tally huge costs. For example, Thunder Horse, the largest moored, semi-submersible oil platform in the world, is operated by British Petroleum (BP, London, UK) in partnership with ExxonMobil (Irving, TX, US) over a well in 1,920m of water, 150 miles off the coast of the US state of Louisiana. It began production in 2008, using a steel catenary riser (SCR) system, but the significant hang-off load created by the steel riser required the producers to spend US$5 billion to build a platform large enough to create displacement sufficient to counter-balance that load, together with costly buoyancy and tensioning systems.

Thunder Horse was a wake-up call for the industry. Since then, industry engineers have been well aware that if they could make and deploy a lighter riser, they could shave billions of dollars from platform costs for deepwater projects.

Although past efforts to develop a composite riser have met with some frustration, in 2016, a joint development agreement by a group of companies shows promise of finally resulting in the first truly commercial, long-term, deepwater, fully composite structural riser applications. A qualification program, funded in part by the UK’s National Composite Centre (Gloucestershire, UK), will run about 30 months and aims to qualify MAGMA Global’s (Portsmouth, U.K.) fully-bonded, flexible, polyetheretherketone (PEEK)-infused carbon/S2 glass pipe, m-pipe, for a jumper application with an unprecedented service life requirement of 25 years. M-pipe is a 100% composite pipe, comprising (approximately) 25% carbon fiber, 25% S2 glass and 50% PEEK, a construction that yields a pipe about one-tenth the weight of steel and traditional unbonded flexibles.

Unbonded pipe, as the name implies, comprises independent, unbonded layers, which by design may “slip” with respect to one another, providing inherent flexibility. On the other hand, Magma’s bonded m-pipe is manufactured by an automated tape laying (ATL) process, which fuses the alternating layers of glass and carbon in a PEEK matrix — a design which requires that flexibility be achieved through material selection and layup architecture. M-pipe is a 100% composite pipe, comprising (approximately) 25% carbon fiber, 25% S2 glass and 50% PEEK, a construction that yields a pipe about one-tenth the weight of steel and traditional unbonded flexibles. Achieving high volume and also repeatable, high-quality parts, often a sticking point in composites manufacturing, is ensured by manufacturing via ATL.

Meanwhile, an unprecedented US onshore energy boom during the past decade has brought the country to near fossil-fuel energy independence and put composite manufacturers to work producing a new, expendable well technology. Credit goes to a technology called hydraulic fracturing, often termed “fracking” or, more correctly, “frac’ing.” As the name implies, the process artificially fractures low-permeability rock strata with explosives and then injects pressurized, sand-laced solutions into those fractures to facilitate oil and natural gas extraction. According to the Society of Petroleum Engineers (SPE, Richardson, TX, US), 60% of all new oil & gas wells globally are frac’ed, and 2.5 million frac’ing procedures have occurred since 2012 — more than 1 million of them in the US alone.

A single wellbore requires 10-40 multi-part, consumable tools called “frac plugs” (and accompanying “frac balls”) to pressurize and perforate multiple oil- or gas-producing layers, called “stages.” Demand for these downhole parts exceeds 20,000 units per week, or more than 1 million units annually, according to one oilfield composites expert. Demand is high for these critical parts, which typically are made with composites because the composite is relatively easy to drill through at the end of the frac’ing operation, to make room for completion equipment (see "A critical market sector: Downhole composites in oil and gas" under "Related Content").

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