When Prudhoe Bay was developed in the 1970’s, about 2 % of the surface area over the field, or 5,000 acres, was covered by gravel for roads and drilling and production facility sites. If Prudhoe Bay were developed today, using lessons learned since the 1960’s, gravel would cover less than 2,000 acres, a 60 % reduction.
Advances in directional, or extended-reach, drilling now allow producing companies to reach a reservoir three miles from the surface location. Soon “extended reach” wells out to four miles will be possible on the North Slope. When Prudhoe Bay was first developed, wells could reach out only one and a half miles.
In the 1970’s, production wells on drill pads in Prudhoe Bay were spaced 100 feet or more apart. New directional drilling techniques and drill equipment allow wells to be spaced 25 to 15 feet apart, and in some cases 10 feet apart. A drill pad that would have been 65 acres in 1977 can be less than nine acres today. The same number of wells that required a 65-acre pad in the 1970’s can be drilled on less than a nine-acre pad today.
Drilling Mud Disposal
New technology allows producing companies to do away with reserve pits for drilling fluid (“mud”) and cuttings. Mud and cuttings are now injected the below-ground through disposal wells.
Ice Roads and Drilling Pads
Instead of building a gravel pad for exploration drilling, companies are now building temporary pads of ice, which disappear after the exploration well has been drilled. Temporary ice roads have long been used to support winter exploration drilling on the North Slope.