Hole opener
![Heavy-duty roller cones hole opener used for offshore drilling](/Images/godic/202501/18/Hole_opener1541.JPG")
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.
Numerous designs exist, in sizes varying from a couple of inches to above 50". Usages range from hydrocarbon drilling operations to water drilling or horizontal drilling.