This case regards GTL’s involvement with BP and their exploration of Northstar Island, an oil-drilling and refinement facility in the Beaufort sea – six miles offshore from Alaska’s North Slope. Being the very first offshore oil production facility situated in an arctic region of the United States, this manmade 4.5 acre gravel island presented a specific set of challenges.
Geotechnical Ground Conditions
The area of North Slope is known for its adverse weather conditions: of long winters and short summers. In spite of this, GTL took on this exploration project, driving piles with APE 200 and Delmag 62 impact hammers to facilitate access.
Inevitably, the PN&D encountered difficult soil conditions. A series of holes, ranging from small-to-large in diameter, were predrilled and filled with a combination of steam and hot water to facilitate access, filling the full length intended for the piles themselves. Once complete, the steel piles would subsequently be put in place.
Thus, in the process, this pilot hole procedure – via thermal manipulation and facilitation – was pioneered. Furthermore, the combined lengths of open cell sheet pile wall totalled approximately 800ft, with the project utilizing 1,049 sheets at up to 60ft in length.