World Oilfield Forum
These are some well control formulas that I have learned from my well control school and I would like to share with you guys. Please feel free to comments or give me suggestions.
Pressure (P) - psi
Pressure (psi) = Force (lb) / Area in Square Inch (in ^{2})
Pressure Gradient (G) - psi/ft
Mud Gradient ( Psi/ft ) = Mud weight ( PPG) x 0.052
Hydrostatic Pressure (HP) - psi
Hydrostatic Pressure (HP) = Mud weight (PPG) x 0.052 x TVD (ft)
You may have seen this triangle before but I need to emphasize on this because it will let you see all relationship of the hydrostatic pressure.
If you want to solve for MW or TVD, fill in the known information in these equations below;
Bottom Hole Pressure (BHP) - psi
Under static condition
Bottom Hole Pressure (BHP) = Hydrostatic Pressure (HP) + Surface Pressure (SP)
Under dynamic condition, use the following equation.
Bottom Hole Pressure (BHP) = Hydrostatic Pressure (HP) + Surface Pressure (SP) + Frictional Pressure (FrP)
Note: Frictional pressure acts opposite way of flow direction.
Formation Pressure (FP) - psi
After get Shut In Drill Pipe Pressure, you can calculate the formation pressure from this following relationship;
Formation Pressure (FP) = Hydrostatic Pressure (HP) + Shut-In Drill Pipe Pressure (SIDPP)
Equivalent Circulating Density (ECD) , ppg
Equivalent Circulating Density (ECD) ,ppg = (annular pressure loss, psi) ÷ 0.052 ÷ true vertical depth (TVD), ft + (current mud weight, ppg)
Leak-off Test Equivalent Mud Weight (LOT), ppg
Leak off test (ppg) = (Leak off test pressure in psi) ÷ 0.052 ÷ (Casing Shoe TVD in ft) + (Mud Weight used for LOT in ppg)
Maximum Initial Shut-In Casing Pressure (MISICP), psi
This calculation is based on shoe fracture which is equal to Leak Off Test Pressure.
MISICP (psi) = [LOT (ppg) – Current Mud Weight (ppg)] x 0.052 x Shoe TVD (ft)
Kill Mud Weight to Balance Formation (KMW), ppg
KWM (ppg) = [Shut In Drill Pipe Pressure (SIDP), psi ÷ (0.052x True Vertical Depth (TVD) of the well, ft)] + Original Mud Weight (ppg)
Slow Circulation Rate (SCR), psi
SCR (psi) = Initial Circulating Pressure (psi) – Shut In Drill Pipe Pressure (psi)
Annulus Capacity Factor (ACF),bbl/ft
Final Circulating Pressure (FCP), psi
Surface To Bit Strokes, strokes
Circulating Time, mins
Capacity Factor (CF), bbl/ft
Opened End Pipe Displacement, bbl/ft
Closed end pipe displacement, bbl/ft
Height of Influx, ft
Approximate gas migration rate, ft/hr
Sacks of Barite Required For Weight-up, sx
Volume Gain From Slug, bbl
Triplex Pump Output (volume), bbl/stroke
Pump Output, bbl/min
New Pump Pressure With New Pump Strokes, psi
Boyle’s Law - Gas Pressure and Volume Relationship
Mud Increment for Volumetric Method (MI), bbl
Lube Increment for Lubricate and Bleed Method (LI), bbl
Bottle Capacity Required, gal
Volume of Usable Fluid, gal
I would be very grateful to get similar post like this, thank you so much.
I look forward to have material about wireline, operation and equipment as well as downhole tools. Regards
Hi Mr Rachain Jetjongjit i was looking for you email to contact you but i can't found in the net any email adress.
Since you are posting many subject related to drilling, I would like if you can help me , I am a drilling engineer , we have a lot of problems due to stuck pipe for 12 ¼ hole section (deviated wells) , I suggest to my manager to use 6 ½ DC in the drilling assembly instead of 8 ½ DC ,this to minimize the chances of back off and deferential sticking , we are using geopilote so we don’t need high weight on bit also the 6 ½ DC it’s stiff enough to control the drilling torque. May be the only inconvenient is the ID 2 1/16 which will give high pressure comparing with 8 ½ DC. If do you have any Idea please contact me at hammae55@hotmail.com.
hammame55@hotmail.com
Thank u so much for sharing this.Keep it up sir
In UBD drilling is that :
P_{bh} = Mud hydrostatic + Annular fractional pressure + Choke pressure.
Correct ?
But I found another Formula said that:
P_{bh} = Mud hydrostatic + Annular fractional pressure + Choke pressure+Acceleration pressure
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