Abstract: This paper has presented a new definition of kick tolerance and unified it with the critical pit gain, allowable pressure of BOP and fracture pressure of bore hole, and thus given the calculation methods and formulas of kick tolerance under conditions of using shut-in wethod etc. systematically. The new definition and its calculation methods are very convenient for drilling engineers to use in the field.

Key words: Bottom hole pressure, Well control, Kick tolerance, Estimation of fracture pressure of formation