The following techniques should be used while drilling Unconsolidated Formations:
1. Obtain maximum annular velocities by using critical velocity circulating rates.
2. Use a "Clayball Trap" or a small settling tank upstream of the shakers.
3. When reaming, avoid scouring the sides of the hole with high jet velocities. When reaming with a jet bit, run the pumps at reduced speed. If much reaming is anticipated, use a four nozzle bit. Increase the frequency of check trips. Drill with reduced rpm if conditions permit.
Note: Use four nozzle bits as standard when reaming in 17 1/2" (or 16") hole.
4. If necessary restrict the penetration rate to limit the generation of solids, and to ensure the solids can be efficiently removed. Alternatively, drill a pilothole first giving a higher penetration rate, without overloading the solids control system. The hole sizes (pilot/ HO hole size) should be selected such that the total hole volume is removed with 50% in each of the two runs.
5. Maintain low solids percentage and a low water loss.