There are other criteria to consider while cleaning deviated wells such as the hole diameter and the deviation angle. As the LCM could plug the bit nozzles in 8 ½ and 6’’ sections and could do the same for the PDM. Therefore, attention should be paid while pumping LCM.
In low angle (<30 deg) wells:
* The transport Velocity is the key
* To increase cuttings removal efficiency
- Increase Annular Velocity
- Increase Mud Weight –If possible
- Increase Mud Properties (YP, Gel Strength)
- Pipe Rotation increases the annular velocity
As hole angle increases, things change; the concentration of cuttings at the low side increases. Cuttings are no longer being supported by the mud and a cuttings bed begins to form.
In high angle wells :> 30°:
- Between 45-55°, avalanching and in the worst case pack off is highly expected in a dirty holes.
- Use tandem Pills: This consists of two pills, a low viscosity pill followed by a viscous weighted pill. The idea is that the low viscosity pill stirs up the cuttings from the low side of the hole and the viscous pill sweeps them out of the hole.
- Consider increasing the circulation rate, drill pipe rotation and reciprocating drill string for a better hole clean
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