Jam clearing process for rotary telemetry tools
A clearing or unjamming process utilizes bidirectional agitation and non-deterministic behavior to clear debris that is jamming a downhole rotary tool. In accordance to at least one embodiment the clearing or unjamming process uses irregular oscillation of the jamming debris which may be produced by varying pause times in a bidirectional movement of the rotor. In some embodiments the rate of acceleration and deceleration of the rotor is maintained constant during the unjamming process.
1. A method, comprising:
operating a pulse signal device in a wellbore, the pulse signal device comprising a motor rotating a rotor relative to a stator to alter a fluid pathway to produce modulated pressure pulses in a drilling fluid column;
detecting a jam in the pulse signal device;
initiating an irregular oscillation clearing process by rotating the rotor to a full open position;
performing a first oscillation process until the jam is cleared or otherwise moving to a second oscillation process, the first oscillation process comprising:
rotating the rotor in a first direction until jammed and then switching directions and rotating the rotor in a second direction to the full open position and pausing for a first pseudo random pause time; and
rotating the rotor in the second direction until jammed and then switching directions and rotating the rotor in the first direction to the full open position and pausing for the first pseudo random pause time; and
performing a second oscillation process comprising:
rotating the rotor in a first direction until jammed and then switching directions and rotating the rotor in a second direction to the full open position and pausing for a second pseudo random time, wherein the first pseudo random pause time and the second pseudo random pause time are different.
2. The method of claim 1 , wherein the initiating the irregular oscillation clearing process further comprises pausing the rotor in the full open position for an initiation pause time prior to performing the first oscillation process.
3. The method of claim 2 , wherein the initiation pause time is longer than the first pseudo random pause time.
4. The method of claim 1 , comprising repeating the first oscillation process prior to performing the second irregular oscillation process.
5. The method of claim 1 , wherein the second pseudo random pause time is longer than the first pseudo random pause time.
6. The method of claim 1 , further comprising using a constant rotor acceleration and deceleration in the first and the second oscillation processes.
7. The method of claim 1 , further comprising pausing the rotor in the full open position for an initiation pause time prior to performing the first oscillation process; and
using a constant rotor acceleration and deceleration in the first and the second oscillation processes.
8. The method of claim 7 , wherein the second pseudo random pause time is longer than the first pseudo random pause time.
9. The method of claim 1 , wherein the initiating the irregular oscillation clearing process further comprises pausing the rotor in the full open position for an initiation pause time prior to performing the first oscillation process; and
wherein the initiation pause time is longer than the first pseudo random pause time and the second pseudo random pause time is longer than the first pseudo random pause time.
10. The method of claim 9 , further comprising using a constant rotor acceleration and deceleration in the first and the second oscillation processes.