Pyrotechnic Initiated Hydrostatic or Boost Assisted Cable Cutter
Publication Date: 2015-Mar-23
The IP.com Prior Art Database
The new tool is a downhole cable cutter. A cable cutter is placed over the wire at surface and dropped into the well. Once the cable cutter reaches the tool head it is activated to cut the wire. The new tool uses a pyrotechnic actuator to burst a rupture disk to initiate the cutting process. The actual cutting process is mechanically powered by hydrostatic pressure or when required a preset surface boost pressure. When the cable cutter reaches the tool head it is initiated by one of (or a combination of): a timer, a proximity sensor, a pressure sensor, a temperature sensor, or a motion sensor. The actuator bursts a rupture disk which allows the either hydrostatic pressure or a preset charge pressure to mechanically drive the cutter knife edge through the wire to release it from the stuck tools.
This invention uses a pyrotechnic initiator (shown below) to burst a rupture disk, to allow hydrostatic pressure to act on a piston to provide the motive force to mechanically cut the wire or cable. If well hydrostatic pressure is low then the tool could be configured at surface with a nitrogen or compressed air boost to provide the required motive force. The pyrotechnic actuator is a simple device that requires very low power to activate. The simplicity and reliability of the device allow for simple and small electronics to control the cutting process.
The pyrotechnic initiated cable cutter requires low battery power which makes it ideal for designing a small over the cable drop type cutter. The low power and simple firing circuit required to initiate the device makes the actuator, electronics, and battery package very small.
In its simplest form the device would activate after an elapsed time or at a specific programmed real time set on the electronics board. For additional safety the timer activation circuit could add interlocks such as (but not limited to):
1. Pressure – tool would only activate after it reaches a certain well pressure
2. Temperature – tool would only activate after it reaches a certain well pressure temperature
3. Motion – tool would not activate while in motion.
4. Detection of the cable head – the tool would not activate until it contacted the cable head
The mechanical activation of the cutter is driven from either hydrostatic pressure or a...