SECURITY STYLE HOLE OPENERS
As a result of insufficient hydraulics, bits and tools can be damaged, penetration rate falls, and the time required to drill a large diameter hole in one pass can be greater than the time needed to drill and then open a pilot hole.
So to optimize surface hole drilling performance, more emphasis needs to be placed on hole opener hydraulics – not just when hole openers are used where hydraulics are insufficient to remove cuttings on one pass, but also anywhere there is a demand for initially small holes to be subsequently enlarged.
This could be as a result of deeper drilling demanding multiple casing strings set at ever increasing depth, or where smaller holes are preferred initially for operational reasons such as ease of logging, or for better directional control when a large number of wells are drilled in close proximity.