You can calculate North, East and TVD between directional surveys based on the Angle Averaging Method as per formula below:
Where;
MD = measured depth between surveys in ft
I1 = inclination (angle) at upper survey in degrees
I2 = inclination (angle) at lower in degrees
Az1= Azimuth direction at upper survey
Az2 = Azimuth direction at lower survey
Calculation example for Angle Averaging Method
Survey 1
Depth = 7500 ft
Inclination = 45 degree
Azimuth = 130degree
Survey 2
Depth = 7595 ft
Inclination = 52 degree
Azimuth = 139 degree
As per formula above,
North = -49.87 ft
East = 50.74 ft
TVD = 62.95 ft
Please find the Excel sheet used for directional survey calculation with Angle Averaging Method
Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition
Directional Drilling Books
