The capacity of a pipeline built to transport crude oil or refined products is often thought to be tied only to the pipe’s diameter and pumps, as well as the viscosity of the hydrocarbon flowing through it. Increasingly, though, midstream companies are injecting flow improvers—special, long-chain polymers known as “drag reducing agents” —into their pipelines to reduce turbulence, thereby increasing the pipes’ capacity, trimming pumping costs or a combination of the two. The role of these agents has evolved to the point that they aren’t simply being considered to boost existing pipelines, their planned use is being factored into the design of new pipes from the start. Today we begin a series on DRAs and their still-growing influence on the midstream sector.
The Shale Revolution has had as big effect on pipeline companies and other midstream players as it has on producers. As new production areas have emerged and some older ones have faded, a number of the crude oil, natural gas, natural gas liquids (NGL) and refined-product pipelines built decades ago have been reversed and/or expanded—and new pipelines have been built—to meet the needs of the new order. Growth in Western Canadian oil sands production has spurred the need for new pipeline capacity too. We’ve blogged extensively about the build-out of crude oil pipeline infrastructure, which continues to this day, despite the overall decline in crude production since the collapse of oil prices in late 2014 and 2015 (see This Pony Knows More Than One Trick, Tighten Up and Let Your Crude Flow for some recent examples). We’ve also discussed the capacity challenges facing the nation’s refined-products delivery networks, the Colonial Pipeline from the Gulf Coast to the Northeast chief among them (see Move It On Over and Looks Like We Made It). And, in our Hey Crude series, we took a nearly comprehensive look at crude pipeline economics; the only thing we didn’t get to in that series was drag reducing agents (DRAs), which we take up today.
While it might seem reasonable to think that refined-products like motor gasoline and diesel and all but the heaviest, thickest crudes flow through pipelines with relative ease, that’s not the case. In fact, flows through crude and refined-products pipelines operate within what’s referred to as a “turbulent flow regime” can be anything but efficient. Within a turbulent flow regime, fluid molecules move in a random manner, and much of the energy applied to them (by pumps and/or downhill gradients) is wasted as eddy currents and other haphazard swirling as the crude or refined product sloshes toward its destination. As the throughput is ramped up, the turbulence increases significantly, causing higher operating pressures and limiting further increases in the throughput. Reducing that turbulence—and the “frictional pressure drop” or “drag” that it creates—is the aim of DRAs. It’s worth noting up front that DRAs are used almost exclusively on transmission pipelines, which either transport hydrocarbon liquids from the central collection points of gathering systems to refineries or storage facilities, or transport refined products (motor gasoline and diesel, but not—as we’ll get to—jet fuel) from refineries to storage, distributors or end users. It typically does not make economic sense to use DRAs in oil gathering systems, however there are exceptions where significant production increase from a given multi-well pad or a field through the existing infrastructure can be achieved by the use of DRAs. We also should point out that while DRAs are not (to say the least!) a common topic of discussion, we understand that roughly three-quarters of the crude oil and refined products barrels flowing through U.S. pipelines as you read this have been DRA-treated.
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