Seeking the Lighter Side of Heavy Duty

Abstract

The weight of a deepwater riser requires a large vessel to bear the weight of the steel pipe running a mile or more from the surface to the ocean floor. The Skandi Aker, which is equipped with a relatively small 7⅜-in. high-pressure riser for well maintenance and construction work, is more than 157 m long, about half the length of the largest cruise ships. Innovators have taken on the challenge of building a riser that will allow smaller boats to do things now only possible with a rig or drillship. More than a decade of work has gone into solving the problem, and no one appears close to getting a product on the market. Their motivation is the many people in the business who expect the added muscle that coiled tubing can provide when working on wells. “Oil companies want to be able, if they have a problem they have to get rough with, to have the equipment to get rough with it,” said Brian Skeels, emerging technologies director at FMC Technologies. Several companies are looking for a way to use coiled tubing deployed off a construction vessel to deliver fluids to the well as a riser does. It would offer a conduit to the for jobs requiring fluids such as acid treatments. The challenge is to maintain enough tension on a pipe from a vessel that is rising and falling with the waves. Baker Hughes is developing what it describes as a riserless coiled tubing intervention system. Unlike the riser, which provides a conduit for coiled tubing, this tubing would act as a pipeline carrying fluids directly into the well, said Lance Portman, vice president of coiled tubing and cementing at Baker Hughes. It could allow smaller vessels to do a greater range of work, for example, by delivering hydraulic fluids to power tools or acid to remove asphaltene. “You have limited options with wireline. With coiled tubing, you have more options,” Portman said. The company developed a system to maintain the tension on the tubing with two devices: one on the boat to adjust for the heaving caused by the waves, and the other on the seafloor that maintains the tension on the tubing. The project with Blue Ocean, which is providing the seafloor equipment needed to safely get the pipe into the well, is years away from having a system to sell.