Reynold number is the important figure because it demonstrates the flow regimes of drilling mud as laminar, transition or turbulent flow in annulus of the wellbore. In order to correctly calculate the Reynolds number, you need to use the effective viscosity, µea, which we already discuss about it from the previous topic.
The following equation is for Reynolds number in the annulus.
Where:
Rea = Reynold Number in the annulus
Va = Annular velocity, ft/min
Dh = Diameter of wellbore, inch
Do = Outside Diameter of tubular, inch
W = mud weight, ppg
µea = effective viscosity in the annulus, centi-poise
na = power law constant
For more understanding, please following this example, Reynold number calculation.
Va = 6 ft/min
Dh = 8.5 inch
Do = 5 inch
W = 9.5 ppg
µea = 42.53 centi-poise
na = 0.514
Rea = 3,781
The next topic will demonstrate you how to relate the Raynold’s number into flow regime.
Reference: Drilling Hydraulic Books
how we can know yeld point and plastic vescosity?
Hi Reben,
Please find the answer below.
Plastic Viscosity (PV) = Reading at 600 rpm – Reading at 300 rpm
Yield Point (YP) = Reading from a viscometer at 300 rpm – Plastic Viscosity (PV)
How recover the core sample (fully sand ) from the depth 500ft to 700ft ?
I don’t have an experience about this topic. Sorry about that.
I was looking at your example calculation. you list the annular velocity in the formula with dimentions of ft/minute but your example data in listed as ft/second. is that a whoops.
Hi Curtis,
Thanks for helping check my typo. It should be ft/min.
Regards,
Shyne
You were correct the first time. It should be ft/sec NOT ft/min.
Hey folks at DrillingFormulas,
I’ve been using your formula above to try and build an excel calc.
But i get the answer Rea 6430 from your example.
Could you show the calculation broken down further? or offer any other possible help.
Thanks
Matt.
Sorted it! 🙂