These are some formulas used in well control operation. I will spit all content into several parts ^_^

**Equivalent Circulating Density (ECD) , ppg**

**Equivalent Circulating Density (ECD) ,ppg = (annular pressure loss, psi) ÷ 0.052 ÷ true vertical depth (TVD), ft + (current mud weight, ppg)**

**Leak-off Test Equivalent Mud Weight (LOT), ppg**

**Leak off test (ppg) = (Leak off test pressure in psi) ÷ 0.052 ÷ (Casing Shoe TVD in ft) + (Mud Weight used for LOT in ppg)**

**Maximum Initial Shut-In Casing Pressure (MISICP), psi**

This calculation is based on shoe fracture which is equal to Leak Off Test Pressure.

**MISICP (psi) = [LOT (ppg) – Current Mud Weight (ppg)] x 0.052 x Shoe TVD (ft)**

**Kill Mud Weight to Balance Formation (KMW), ppg**

**KWM (ppg) = [Shut In Drill Pipe Pressure (SIDP), psi ÷ (0.052x True Vertical Depth (TVD) of the well, ft)] + Original Mud Weight (ppg)**

**Slow Circulation Rate (SCR), psi**

**SCR (psi) = Initial Circulating Pressure (psi) – Shut In Drill Pipe Pressure (psi)**

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

**Well Control Books**