New drilling technology brings profit to slope operations: Alaska's North Slope is the first to use widespread application of revolutionary drilling technologies.

• Author: Bradner, Mike

Within the world's petroleum industry, Alaska's North Slope is becoming known as a place for innovation and application of new oil and gas drilling and well-completion technologies. Some of these, like coiled-tubing drilling, were clearly invented and applied first on the North Slope. While there is some debate over whether horizontal drilling and multilateral and designer production wells were done first in Alaska or elsewhere, it is clear that the first widespread application of these revolutionary technologies is on the North Slope.

The Alpine oil field, for example is the first field being developed from the start with horizontal production wells. Multi-lateral horizontal wells also are now the preferred option-the only option, in fact, for development of the North Slope's huge viscous and heavy oil resources.

North Slope drilling contractors also are on the forefront in new adaptations of drilling equipment. Doyon Drilling, for example, has designed its rigs to be very mobile so they can be moved efficiently from one location to another.

All of these techniques were developed to overcome particular challenges that presented themselves on the Slope. The big driver was the need to reduce costs as the big oil fields passed their peak production years and began their decline. Another push was to develop economically challenged reservoirs, like the West Sak and Schrader Bluff viscous oil deposits.

TECHNOLOGY OF TODAY

Here's a rundown on the new drilling techniques: Coiled-tubing wells are drilled with truck-mounted coiled-tubing units instead of conventional rotary drills. The goal is to reduce the cost of the well by using a system that is less costly than a drill rig. With coiled tubing, the drill bit, motor and assembly work at the end of a long string of flexible metal tube that is lowered from a truck-mounted unit at the surface. The tube is coiled on the truck, hence the name.

Drilling wells with coiled tubing is an Alaska innovation. Producing companies and contractors have used coiled-tubing units for years in routine well maintenance and jobs like well-logging, but in the 1980s people got the idea that actual drilling could be done with them as well.

Horizontal wells, as the name implies, are drilled laterally through the oil-producing formations. These are initially done to tap thin layers of oil-bearing rock strata in the producing fields that were bypassed earlier by conventional vertical production wells. In a horizontal well, more of the well is exposed to the producing formation, and more oil is produced.

In the older fields, the horizontal well is usually done as...