Open And Close Drill Bit
An open and close drill bit (also known as an opening drill bit or underreamer) features cutting elements that can be mechanically expanded (opened) and retracted (closed) while downhole. This allows the bit to pass through a restricted casing window or smaller borehole section, then expand to drill a larger diameter below. It's an essential tool for through-tubing drilling, casing exits, and selective underreaming operations where conventional fixed-diameter bits can't be used.
Core Advantages:
- Expandable cutting arms activated by hydraulic pressure or mechanical linkage
- Drills diameters 1.5x to 3x larger than the entry hole size
- Eliminates the need to trip out to change bit sizes
- Closes for safe retrieval through restricted casing IDs
- Available in PDC and roller cone cutter configurations
- Standard API connections for integration with existing BHA assemblies
Q: How does an open and close bit know when to expand?
A: Most designs use a pressure differential—when circulation is established at the desired depth, increased pump pressure activates the expansion mechanism. Some models use a mechanical ball-drop system for more positive activation control. Always verify activation with a surface pressure test before drilling.
Need to enlarge your borehole below casing without tripping? Our open and close drill bits are engineered for reliable downhole activation. Contact us with your casing ID and target hole size for a custom solution.
