I have some directional calculations that I’ve shared with you. However, some of them are not shared yet so I will try to share all directional drilling formulas that may be helpful for you in the future.
Today, I would like to show you about Balanced Tangential Method Calculation. This calculation method treats half of the measured distance (MD/2) as being tangent to I1 and Az1 and the remainder of the measured distance (MD/2) as being tangent to I2 and Az2.
The formulas for the balanced tangential method are listed below;
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
The following example is the Balanced Tangential 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
As per the formulas above, you will get answers as listed below;
North = 27.1 ft
East = 19.37 ft
TVD = 93.61 ft
Please find the Excel sheet used for The 
Balanced Tangential Method Calculation
Reference books: Directional Drilling Books
Formulas and Calculations for Drilling, Production and Workover, Second Edition
