What's new in production
With near-invisibility, a technology formerly regarded with skepticism by industry traditionalists has threaded its way across the oil field and into mainstream use. It’s nearly invisible, that is, until you encounter a truck on its way to a flowline installation job, bearing enormous reels (or spools) of composite pipe.
Said enormity is limited only by truck and highway size; on the manufacturing side, lengths that can be produced by machines, somehow reminiscent of giant pasta makers, are restricted, in theory, only by handling capability and volume of materials on hand.
Therein lies the beauty of spoolable composite pipe—its length. Actually, this beauty lies in a trench, which is dug in advance of installation. The efficiency of the installation process is fun to watch: the truck drives up to the trench, and the flowline is unspooled into it. There’s no need to make up threaded connections of steel (or fiberglass) sticks. Welders need not apply. In fact, for some limited-length flowline applications, the only connections needed are the service-end connectors on either end of the line.
As for installation efficiency, NOV’s Fiberspar group claims that, depending on pipe size and reel capacity, continuous sections up to 2 mi in length can be installed in a single pass. Lay rates of 10,000 ft or more, per day, are possible. For quick road and pipeline crossings, the pipe can be pulled through boreholes below grade.
Making a connection. So far, so good, but what happens when the pipe on the reel, on the truck, isn’t as long as you need? That’s when you do need a connection—they’re called joining systems by the cognoscenti—and the various developers of this technology have given how to do this a lot of thought. For example, butt wrap, perhaps the industry’s most vivid generic term, is one of several methods offered by NOV. The company’s mechanical connectors are offered in two flavors: pipe-to-pipe connectors, to join two lengths of pipe; and various service-end connector types, to join the pipe to the system, or to existing lines. Connectors from all suppliers are typically rated to at least the strength of the pipe itself.
But back to the pipe—a variety of pipe designs fall under the generic moniker of spoolable composite pipe. These include dry-glass fiber, aramid and carbon or steel reinforcing. For production flowline applications, NOV’s Fiberspar design is instructive. (They claim a current installed base of nearly 80 million ft). Its inner, thermoplastic pressure barrier is reinforced by high-strength glass fibers embedded in an epoxy matrix. The company says it is intended for sweet or sour oil or gas gathering lines, and high-pressure water or CO2 injection systems. An outer, UV-protection layer is also present.
There are certainly lots of good reasons why composite spoolable pipe is proliferating like kudzu. Starting with the obvious, it’s noncorrosive. By all accounts, it also has lower installed, and operating, costs compared to steel or stick fiberglass. The installation part is easy to believe, if you’ve ever seen it done. And, it makes corrosion-mitigation costs go away.
For the supplier, the reels are an unavoidable logistical factor in deployment. Typical are reusable steel reels. Offsetting their durability is the requirement that, like an empty airliner, they must be deadheaded back to the factories, to be respooled. One supplier, PipeLife, gets around this by using cleverly designed, disposable wooden reels, which they say eliminates reel deposits and reel-rental charges, and lowers transportation costs.
Beneficial side effects. The technology has some other side effects. The smoother interior pipe surface increases efficiency and resists scale/paraffin build-up. In some applications, the pipe ID—and its cost—can be reduced. Increased flow efficiency also enables another capability: under certain conditions, existing steel flowlines can be permanently remediated by pulling composite pipe through them. Despite reduced flow area, better flow properties typically result, with no change in capacity or pressure drop.
For new installations of pipelines beyond flowline applications, another interesting capability made possible by composite materials is offered by Smartpipe. The company’s embedded fiber-optic monitoring system enables the pipeline operator to react more quickly to potential events. According to Smartpipe, events detected by monitoring can be located with an accuracy of approximately 1.0 m. Monitoring can identify leaks, pipeline movement, and third-party intrusion, said to be the most common cause of pipeline accidents.
Spoolable pipe has come of age. More quietly than your children, composite spoolable pipe has come of age, said age actually being greater than you may realize. Numerous interested parties have been beavering away at this for some time, going back at least as far as 1998. In that year, a JIP was created that brought together manufacturers; users, such as Saudi Aramco, Petrobras, Shell and BP; and testing institutes to develop a standard to meet their demands. Several standards have been established along the way, which include API 15 HR: Specification for High Pressure Fiberglass Line Pipe; API 15 S: Qualification of Spoolable Reinforced Plastic Line Pipe; CSA Z662 Section 13.1: Fibreglass Pipeline; ASTM D2996: Standard Specification for Filament-Wound Glass-Fiber-Reinforced Thermosetting-Resin Pipe.
It may be mature, but the technology is still learning new tricks. In the meantime, if you’re ever asked to witness an installation, a word of advice: get there on time. Those trucks can get far away, fast.
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