Minimum Curvature Method

The Minimum Curvature Method smooths two straight-line segments of the Balanced Tangential Method by using the Ratio Factor (RF).

The formulas for the Minimum Curvature Method are listed below;

ß must be in radians

MD = Measured Depth between surveys in ft
I1 = Inclination (angle) of upper survey in degrees
I2 = Inclination (angle) of lower in degrees
Az1= Azimuth direction of upper survey
Az2 = Azimuth direction of lower survey
RF = Ratio Factor
ß  is the dog leg angle.

The following example is the Minimum Curvature Method Calculation

Survey 1
Depth = 3500 ft
Inclination = 15 degree (I1)
Azimuth = 20degree (Az1)

Survey 2
Depth = 3600 ft
Inclination = 25 degree (I2)
Azimuth = 45 degree (Az2)

MD = 3600 – 3500 = 100 ft

ß  = 0.22605 radian = 12.95 degree

RF= 1.00408

As per the formulas above, you will get answers as listed below;

North = 27.22 ft
East = 19.45 ft
TVD = 94.01 ft

Please find the Excel sheet used for The Minimum Curvature Method Calculation

Reference books: Directional Drilling Books

Drilling Formula Book Formulas and Calculations for Drilling, Production and Workover, Second Edition

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6 Responses to Minimum Curvature Method

  1. deyaa says:

    very simple and very cool, thanks

  2. Mr. Phillip Sand Hansel II says:

    In the Minimum Curvature calculation of the Ratio Factor, Beta is shown in radians on the left, but in degrees on the right. Below the initial formula it mentions that “Beta must be in radians”. Is the equation valid with mixed units for Beta?

  3. Mr. Phillip Sand Hansel II says:

    I know it is bad form, but I’ve answered my own question; the solution for RF incorrectly shows degrees where it should show radians (in order to get the calculation to match the results). The “excel solution” spreadsheet is nice, but since it is locked, one cannot view the entire formula. This required extra effort to determine how the equation should be rendered in excel. I did eventually get it to work, so I am grateful for the example.

  4. Rikie says:

    very helpful in my calculations.Thanks!

  5. Steve says:

    Is there any way to get an unlocked version of the Minimum Curvature Method spreadsheet? I am having a hard time reproducing the calculations in Excel

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