Well volumes & circulation time
Annular and string volumes section by section, then the strokes and the minutes to bottoms-up and to a full circulation.
Drilling
Bit hydraulics & nozzle selection
Total flow area, nozzle pressure drop, HSI and jet impact force — plus the nozzle size that would put the optimum share of pump pressure at the bit.
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How it is calculated
- TFA = Σ π(d/32)²/4 over the open nozzles.
- Bit pressure drop = ρQ²/(12042·Cd²·TFA²) in ppg, gpm and in².
- Nozzle velocity = 0.32086·Q/TFA (ft/s); impact force = ρ·Q·Vn/1930.4 (lbf); HSI = ΔPbit·Q/1714 divided by bit face area.
- Optimum sizes are back-solved from 65 % of standpipe pressure (maximum hydraulic horsepower) and 48 % (maximum impact force).
Standards it speaks
Where this stops being true
The discharge coefficient is an assumption, not a measurement: 0.95 is right for a clean, round, new nozzle and wrong for a worn or partially plugged one, and the pressure drop goes as 1/Cd². A bit that has been on bottom for eighty hours is not this calculation. The optimum-share rules are also rules of thumb from roller-cone practice — on a PDC in a hard formation they are, at best, a starting point.
The capability that automates this
- DR-01Real-Time ROP OptimizationRate of penetration is how fast the bit makes hole. This recommends the weight and rotation speed that make it fastest without wrecking the bit.
- DR-06Real-Time Torque, Drag & HydraulicsCompares what the string should weigh and how hard the pumps should work against what is actually measured, and flags the gap.
Related tools
ECD & bottom-hole circulating pressure
Annular pressure loss, flow regime and the equivalent circulating density the formation actually sees while the pumps are running.
Directional survey — minimum curvature
Paste MD, inclination and azimuth and get TVD, northings, eastings, dogleg severity, vertical section and closure — with the well path drawn.
Kill sheet — driller's method
Kill mud weight, initial and final circulating pressure and the step-down schedule, for rehearsal and for checking a sheet that has already been worked.
Training aid