A hole opener is a device used to enlarge the borehole during a well drilling operation. It can be positioned either above the drill bit or above a pilot run inside the existing borehole. Usages range from hydrocarbon drilling operations to water drilling or horizontal drilling. Hole openers are also used when a hole must be logged, since logging tools generally cannot handle holes larger than 17 and a half inches in diameter. Hole opener arms have to sustain heavy loads during operations and are generally made of high-grade alloy steel, welded onto a solid alloy steel body. Some designs feature replaceable arms, allowing for size changes but decreasing overall robustness. Numerous designs exist, in sizes varying from a couple of inches to above 50". They can have rolling cutters or drag blades, and can be used for either direct or reverse circulation applications.
See also Casing cutter Drilling rig Driller (oil) Drag bit Drill bit Drilling stabilizer
References
External links Types of Hole Openers Halliburton PDC hole opener