February 1999 Vol. 220 No. 2  Drilling

J. John Grow,  Engineering Editor

Down cycle continues as technology advances

It looks like most of the economic forecasts for drilling, and the near-term, overall O&G picture is pretty bleak. From majors and independents to service companies, one thing can be agreed upon — if the selling price of a barrel of oil doesn’t offset its costs, the O&G industry will continue to suffer. Worldwide E&P expenditures fall when profits are minimal (or non-existent), resulting in decreased exploration and drilling activities.

The U.S. (and world) looks to OPEC for control of oil oversupply, to bring it into balance with demand. But even if OPEC fails to control oversupply, Asian recovery (increased demand) could take care of the 5% surplus reported by EIA, November 1998.

This month’s column presents: Global’s annual SCORE analysis, a one-trip hydrostatic-set window milling system to help save trip time, and the way we may drill wells in the future — a casing-drilling success story from our Canadian neighbors.

Offshore rig markets end 1998 in decline. According to Global Marine’s Summary of Current Offshore Rig Economics (SCORE), worldwide rig markets fell 9.6% from November 1998, to 50.7% in December, and down 29% from 1997’s December SCORE.

Global Marine’s President and CEO, Bob Rose noted that persistently weak oil prices made offshore drilling markets increasingly difficult as 1998 progressed, and tougher times are expected in 1999. He commented, "Even if drilling activity were to turn around today, economic recovery for rig day-rates could lag behind by as much as a year."

During Global’s annual SCORE media briefing, Rose offered perspectives on how the entire oil-services sector must evolve beyond companies with deepwater-drilling capabilities into agile, hardy businesses able to service now-mammoth, E&P companies. "The drilling market needs consolidation for size and scope to provide new, mega-companies with proper service and better value," he noted. When asked if Global had its sites on a particular company for consolidation, Rose would not comment, but emphasized that Global "is looking for opportunities."

One-trip hydrostatic-set window milling system. Baker Oil Tools has designed a milling system to permanently orient, set and anchor the whipstock, and mill a cased wellbore window in a single trip, for sidetracking, re-entry or custom multilateral operations. The system consists of a measurement- while- drilling (MWD) tool, window and watermelon mills, a WindowMaster whipstock, an integral hydrostatic setting tool and a whipstock packer.

The combination anchor-packer-whipstock-milling assembly incorporates a triple-mill configuration that comprises a patented Metal Muncher window mill and two watermelon mills, separated by a specifically designed flex pipe. In operation, the undersized window mill makes the initial cut and mills a window, while the watermelon mills, which are run on the same assembly, fully clean the window to gauge.

As the result of an innovative kick-off lug that keeps the window mill from whirling while the initial cut is made, damage to the Metal Muncher inserts is minimal, maintaining the mill’s original-gauge OD.

First success with casing-drilling. Tesco Corp. has successfully completed drilling a vertical well using casing-drilling technology, setting the stage for full field commercial trials during first half, 1999.

Casing drilling has potential to dramatically change the way future wells are drilled. With casing drilling, wells are drilled without drill pipe. Instead, the well is drilled with standard oilfield casing, which remains downhole at all times. The drill bit and other downhole tools are retrieved and run by wireline within the casing, and are latched to the last casing joint. Since casing drilling eliminates drill pipe use, time required to trip, or to pull and reconnect drill pipe is also eliminated. In addition, because casing remains downhole at all times, wellbore integrity is preserved and many problems associated with unscheduled drilling events are eliminated. Tesco believes that casing drilling could have significant worldwide commercial potential.

The well was drilled to 120 ft using 9-5/8-in. casing, to 577 ft using 7-5/8-in. casing, and to 3,040-ft TD with 5-1/2-in. casing. During drilling, two larger challenges for vertical-well applications were overcome, i.e., casing-connection durability and latching/unlatching downhole-drilling assembles by wireline.

Types of formations drilled were coal seams, hard consolidated sands and shale. Casing was rotated and mud-motor drilled (slide) over 197 ft of the hole.

A successful coring operation was accomplished over a 25-ft interval using wireline-retrievable tools with full-core recovery. At 1,732 ft, the casing was tripped and a 79-ft section was drilled using conventional drill pipe and collars. Penetration rates recorded while drilling with casing equaled those obtained while drilling the 79-ft section with conventional drill pipe.

Tesco has begun construction of a trailer-mounted drilling rig with a top drive designed for casing drilling. Commercial field trials are scheduled to commence in Alberta, April 1999, on a series of shallow vertical wells, to further evaluate this new process.

In response to O&G operators interested in drilling with casing in directional wells, Tesco is currently drilling and evaluating a directional well using casing-drilling technology. Another well, drilled in January 1999, will help further evaluate advanced casing-drilling tools and techniques.

Copyright © 1999 World Oil
Copyright © 1999 Gulf Publishing Company