- #1
Claudio_Baldo
- 14
- 0
I am trying to program a MWD (monitoring while drilling) software for a Exploration Driller and I was wondering if the forum could confirm what I have found out.
I need to calculate the WOB (weight on bit) and Head Torque, I do the following direct reading:
WOB:
Pushdown pressure (PSI). = Ppd
HoldBack pressure (PSI). = Phb
String weight is easily calculated as the sum of the number of rods+head weight+hammer weight. Sw
Theoretically the depth of the hole does not matter, air is used to take out the cutting from the bottom hole, so I neglect any buoyancy factor.
The WOB result should be WOB=Sw+Fpd-Fhb.
Where Fpd is the pushdown thrust calculated as:
Fpd=Ppd*(2*pi*Rp1^2) Rp1 is the radious of piston1
Fhb=Phb*(2*pi*Rp2^2) Rp2 is the radious of piston2
For the Torque on the Hammer, I will be equal to the torque generated by the hydraulic motor which rotates it:
Direct reading:
Pressure of the hydraulic motor (PSI) = Pm
Flow Rate of motor=Fm
RPM
Torque= (Fm*Pm*36.77)/RPM
I am confident in the calculation of the torque, not 100% sure about the WOB.
Did I semplify the model too much?
Are there any other contributes to be taken into account?
Thanks to everyone who can help me out with this model.
I need to calculate the WOB (weight on bit) and Head Torque, I do the following direct reading:
WOB:
Pushdown pressure (PSI). = Ppd
HoldBack pressure (PSI). = Phb
String weight is easily calculated as the sum of the number of rods+head weight+hammer weight. Sw
Theoretically the depth of the hole does not matter, air is used to take out the cutting from the bottom hole, so I neglect any buoyancy factor.
The WOB result should be WOB=Sw+Fpd-Fhb.
Where Fpd is the pushdown thrust calculated as:
Fpd=Ppd*(2*pi*Rp1^2) Rp1 is the radious of piston1
Fhb=Phb*(2*pi*Rp2^2) Rp2 is the radious of piston2
For the Torque on the Hammer, I will be equal to the torque generated by the hydraulic motor which rotates it:
Direct reading:
Pressure of the hydraulic motor (PSI) = Pm
Flow Rate of motor=Fm
RPM
Torque= (Fm*Pm*36.77)/RPM
I am confident in the calculation of the torque, not 100% sure about the WOB.
Did I semplify the model too much?
Are there any other contributes to be taken into account?
Thanks to everyone who can help me out with this model.