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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

Where;

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)

**Solution:**

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**

**Formulas and Calculations for Drilling, Production and Workover, Second Edition**

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very simple and very cool, thanks

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?

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.

very helpful in my calculations.Thanks!

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