Microhole research pioneers new tools

According to a report from the U.S. Department of Energy a research initiative into microhole drilling for oil and gas is starting to bear fruit, with several new tools near commercial realization. Microhole drilling involves using a coiled tubing drilling rig to drill very small diameter wells, a technique that would enable relatively low cost drilling, especially in the development of marginal or declining oil and gas fields. The rigs used for microhole drilling are more easily transported, leave a smaller environmental footprint and generate less drilling waste than conventional rigs, DOE says.

For more than 10 years drilling crews on Alaska’s North Slope have used coiled tubing technology to increase drilling speeds and to facilitate precision directional drilling — drilling mud pumped down the tubing in the well powers a steerable drill bit. But DOE hopes that the development of new drilling tools under its $20 million, cost-shared microhole program will expand the use of coiled tubing technology in the United States.

In particular, new “smart” steering motors and logging-while-drilling systems, as small as 2-3/8 inches in diameter, will enable precision drilling of very small diameter wells, DOE says. Apparently BP has successfully tried the use of these tools on the North Slope. And the development of a miniature, wireless steering-while-drilling system is in the works. Other tools in the advanced stage of development include a prototype miniature drilling tractor to pull coiled tubing through a well and exert pressure on the drill bit; and a radar navigation and radio transmission system for microholes, to “see” ahead of the drill bit while drilling.

—Alan Bailey