Circulation

{
  "id": "MLC-T-OAG-000676",
  "term": "Circulation",
  "field": "Oil and gas",
  "definition": "The movement of drilling fluid from the surface pits down the drill string, out through the bit nozzles and back up the annulus, where it is cleaned and returned to the pits. Circulation cools the bit, lifts cuttings out of the hole and keeps the fluid column acting on the formation. The bottoms-up time covers only the annulus leg from bit to surface, and the full loop adds the pump-down time through the string.",
  "subject": "Drilling",
  "url": "https://mlchart.com/terminology/oil-and-gas/circulation/"
}