The **tangential method** is the simplest calculation among other directional survey calculations.

The tangential method formulas 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 Tangential Method Calculation.

** Survey 1**

Depth = 3500 ft

Inclination = 15 degree (I1)

Azimuth = 20 degree (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 = 29.88 ft

East = 29.88 ft

TVD = 90.63 ft

Please find the Excel sheet used for The Tangential Method Calculation

**Reference books:** ** Directional Drilling Books
**

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

i acknowlegde this site for their work well done.

There are several methods that can be used to calculate the survey data, of these some are accurate while are other may produce some error for a given situation.

Some of the most common methods used for survey calculation in the industry are:

Tangential method (Least Accurate)

Balanced Tangential method

Average Angle method

Radius of Curvature method (Most Accurate)

Minimum Curvature method (Most Accurate)

You’ve done a fine job, I thank you for sharing your knowledge.

xls file is password protected. plz give me that password

Which sheet do you need to be unprotected? I can do it for you but I cannot give you the password.