You know how the maximum allowable shut in casing pressure (MASICP) from the leak off test data and your current mud weight in the well. Moreover, you can use the MASICP to determine the maximum influx height that you can be able to control in the well control situation.

The following formula shows how to determine the figure:

**Influx Height = MASICP ÷ (current mud gradient – influx gradient)**

**The unit of each parameter is listed below:**

Influx height in ft

maximum allowable shut in casing pressure (MASICP) in psi

current mud gradient in psi/ft

influx gradient in psi/ft

Note: if you can convert mud weight into psi/ft, please read this link, **convert mud weight to pressure gradient**.

**With this following information, determine the maximum influx height.**

maximum allowable shut in casing pressure (MASICP) = 900 psi

Mud gradient = 0.55 psi/ft

Influx gradient = 0.13 psi/ft

**Maximum influx height = 900 ÷ (0.55-0.13) = 2143 ft**

**Please find the excel sheet for calculating the maximum influx height. **

**Ref book: ** **Formulas and Calculations for Drilling, Production and Workover, Second Edition**