Two Platforms, Two Shore Approaches, Two Lines And A Hurricane

By Angus W. Stocking | December 2013, Vol. 68 No. 12

Pilings
Meanwhile, Corman installed a series of wooden pilings to guide the steel pipe portion of the product from the north shore to the north platform. The pilings held the steel pipe in place laterally as it was pulled along the river bottom to the platform by crane barge and winch. The riverbed was more abrasive than expected and weld coatings had to be reapplied. A roller and crane were used to hoist and support the product over a local road, keeping it open for the duration of the project. The HDPE portion of the product bundle was shackled to the steel pullhead on the platform. After a 29-hour continuous pull (extended due to necessary reapplication of weld coating) the middle Line A crossing was accomplished successfully.

That left the Line B platform-to-platform as the final HDD crossing of the project. Equipment was shifted and, as with the north shore-to-platform crossing, a steering wire was run through the Line A HDPE so that Para-Track II-equipped bottom hole assemblies could successfully complete the intersect.

But then Hurricane Irene rolled in. "Fortunately, by the time Hurricane Irene reached us, it had been downgraded from a level three hurricane to a level one tropical storm," Curtiss explains, "But we still didn't take it lightly -- there was just too much at stake." Following the contingency plan that had been in place from the beginning of the project, shore-based equipment was chained down and all platform equipment was offloaded onto barges and pushed upriver to a sheltered inlet. The entire procedure took two days. When the storm passed, it took an additional two days to reset equipment. In total, a week was lost to Tropical Storm Irene.

Reaming and swabbing took place as on Line A. But a new technique was employed when transporting the steel pipe from shore to the north platform. To avoid the abrasive bottom, "We came up with a method that let us float the pipe out rather than dragging it," says Curtiss. Using a system devised by Curtiss and Prout, hundreds of crab buoys were used to support the pipe as it was towed to position.

Unfortunately, what should have been the final product pullback wasn't quite as picturesque. Though the eight-inch steel crossed successfully, the HDPE line failed after about 5,000 feet had been pulled.

HDPE drill
The failure of the three-inch HDPE wasn't exactly a shock, according to Curtiss; "We knew we were pushing the limits of HDPE pull back with the two long crossings," he says, "The last one just didn't make it. Fortunately, we had contingency plans in mind."