Drilling Ahead

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

Views: 31270

Tags: control, formulas, well

Comment by Ibnu Fajar on December 5, 2011 at 11:44pm

I would be very grateful to get similar post like this, thank you so much.

Comment by Ibnu Fajar on December 5, 2011 at 11:46pm

I look forward to have material about wireline, operation and equipment as well as downhole tools. Regards

Comment by atmane on February 1, 2012 at 6:42am

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.    


Comment by atmane on February 1, 2012 at 6:44am


Comment by J.Arul Phinehas on February 22, 2012 at 8:17pm

Thank u so much for sharing this.Keep it up sir

Comment by zattamimi on April 12, 2013 at 10:56am

In UBD drilling is that :

Pbh = Mud hydrostatic + Annular fractional pressure + Choke pressure.

Correct ?

Comment by zattamimi on April 12, 2013 at 10:58am

But I found another Formula said that:

Pbh = Mud hydrostatic + Annular fractional pressure + Choke pressure+Acceleration pressure


You need to be a member of Drilling Ahead to add comments!

Join Drilling Ahead

Sign Up To Receive Special Offers
Sign Up Here

Oilfield Gifts

Oilfield Drill Pipe Tally Books


Oilfield Jewelry Drill Pipe Elevators


Oil and gas Gift Pump Jack Music Box



Oilfield Keychains


© 2015   Created by Drilling Ahead.

Badges  |  Report an Issue  |  Terms of Service