Determine surge and swab pressure method 2

This is another method for calculating surge and swab pressure. With this method, there are 3 assumptions as follows:

 

• Closed ended pipe (plug flow)

• Laminar flow around drill pipe

• Turbulent flow around drill collar

How to determine surge and swab pressure with this method

1. Determine pressure around drill pipe

2. Determine pressure around drill collar

Note: The calculation methodology is different from the first method because both pressure losses are determined by separate set of equations.

3. Determine total pressure loss by summation of step 1 and step 2

4. Determine surge and swab pressure

 

 Determine pressure loss around drill pipe by following calculations

 

1. Determine fluid velocity around drill pipe

Where;

Vdp is the fluid velocity around drill pipe in ft/min.

Vp is pipe movement velocity in ft/min.

Dp is drill pipe diameter in inch.

Dh is hole diameter in inch.

2. Maximum pipe velocity

Vm = Vdp x 1.5

Where;

Vdp is the fluid velocity around drill pipe in ft/min.

Vm is maximum pipe velocity.

 

3. Determine n

Where;

n is the power law exponent.

Θ600 is a value at 600 viscometer dial reading.

Θ300 is a value at 300 viscometer dial reading.

 

4. Determine K

Where;

K is the fluid consistency unit.

Θ300 is a value at 300 viscometer dial reading.

n is the power law exponent.

 

5. Determine shear rate of drilling mud moving around drill pipe

Where;

 

Ym is shear rate of drilling mud moving around drill pipe.

Vm is maximum pipe velocity.

Dp is drill pipe diameter in inch.

Dh is hole diameter in inch.

 

6. Determine shear stress of drilling mud moving around drill pipe

 

T= K (Ym)n

 

Where;

T is shear stress of drilling mud moving around drill pipe.

K is the fluid consistency unit.

Ym is shear rate of drilling mud moving around drill pipe.

n is the power law exponent.

 

7. Determine pressure loss around drill pipe

Where;

Pdp is pressure loss around drill pipe.

T is shear stress of drilling mud moving around drill pipe.

Dp is drill pipe diameter in inch.

Dh is hole diameter in inch.

Ldp is drill pipe length in ft.

 

Determine pressure loss around drill collar by following equations.

1. Determine fluid velocity around drill collar

Where;

Vdc is the fluid velocity around drill collar in ft/min.

Vp is pipe movement velocity in ft/min.

Dc is drill collar diameter in inch.

Dh is hole diameter in inch.

 

2. Maximum pipe velocity

 

Vm = Vdc x 1.5

 

Where;

Vdc is the fluid velocity around drill collar in ft/min.

Vm is maximum pipe velocity.

 

3. Determine equivalent flow rate in gpm due to pipe movement

Where;

Q is equivalent mud flow rate in gpm.

Vm is maximum pipe velocity.

Dc is drill collar diameter in inch.

Dh is hole diameter in inch.

 

4. Determine pressure loss around drill collar

Where;

Pdc is pressure loss around drill collar in psi.

MW is mud weight in ppg.

Q is equivalent mud flow rate in gpm.

PV is plastic viscosity in cp.

Ldc is length of drill collar in ft.

Dh is hole diameter in inch.

Ddc is drill collar diameter in inch.

 

The summation of pressure loss around drill pipe and drill collar is total pressure loss.

 Total pressure loss = Pdp + Pdc

 

Determine surge and swab pressure with following equations:

Surge pressure = Hydrostatic pressure + Total pressure loss

Swab pressure = Hydrostatic pressure – Total pressure loss

Reference book: Drilling Formula BookFormulas and Calculations for Drilling, Production and Workover, Second Edition

Related Post

Drilling Formula Calculation Sheet V1.1 I update some useful drilling formulas into the drilling formulas spread sheet called version 1.1. Please feel free to download. Click Here >&g...
Determine Bottom Hole Pressure from Wellhead Press... Gas behaves differently from fluid therefore you cannot use a simple hydrostatic formula to determine reservoir pressure. Gas is compressible but flui...
Lag Time for Drilling Business and How to Calculat... I got an email from Sanan asking me about how to calculate lag time. First of all, you need to know what the lag time is. Lag time is traveling t...
Drill pipe pulled to lose hydrostatic pressure You previously learn about hydrostatic pressure lose due to pulling out of hole . This post will use the same concept but we will determine how many f...
Share the joy
  • 8
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
    8
    Shares
Tagged , , , . Bookmark the permalink.

About DrillingFormulas.Com

Working in the oil field and loving to share knowledge.

3 Responses to Determine surge and swab pressure method 2

  1. wilson gallo says:

    I agree with the procedure for this calculation, but i don´t understand how it works if i pretend know the better Vp for a safe trip?

    Vp is a data, right!.. where i could find it?

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.