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.

Continue reading

Determine surge and swab pressure for open-ended pipe

You’ve learn how to determine surge and swab pressure from the previous topic (Surge and swab pressure method 1) and this topic will demonstrate you how to use those equations to determine surge and swab pressure for the open-ended pipe.

 

Example

 

The well information is listed below:

θ300 = 85

θ600 = 130

Hole diameter = 9 inch

Drill Collar = 6.25 inch

ID of drill collar = 2.5 inch

Drillpipe diameter = 5 inch

ID of drill pipe = 3.5 inch

Average pipe running or pulling speed = 250 ft/min

Drill Pipe Length = 12000 ft

Drill Collar Length = 800 ft

Current Mud Weight = 12.5 ppg

Well TVD = 9000 ft

Continue reading

Surge and Swab Calculation Method 1

This is the first method to determine surge and swab pressure.

Learn more about Surge Pressure and Swab Pressure

Surge is additional pressure due to pipe movement downward and swab is reduction of pressure due to upward movement of drill string.

Bottom hole pressure is reduced due to swabbing effect.

Bottom hole pressure is increased due to surging effect.

 

 

Continue reading

Cutting Slip Velocity Calculation Method 2

This is another method to determine cutting slip velocity. The process of calculation is quite different from the first method however it is still straight forward calculation. It still gives you the following answers: annular velocity, cutting slip velocity and net velocity.

 

Let’s get started with this calculation method.

 

1. 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.

Continue reading

Cutting Slip Velocity Calculation Method 1

Cutting slip velocity is velocity of cutting that naturally falls down due to its density. In order to effectively clean the hole, effect of mud flow upward direction and mud properties must be greater than cutting slip velocity (settling tendency of cuttings). Otherwise, cutting will fall down and create cutting bed.

You can learn more detail about it via this topic -> Cutting Slip Velocity

This calculation will show annular velocity, cutting slip velocity and net velocity so you can use as a reference for you hole cleaning indication.

There are 2 calculation methods and I will show the first method via this topic.

Continue reading