Calculation of Maximum Allowable Annular Surface Pressure (MAASP)
The Maximum Allowable Annular Surface Pressure (MAASP) equals the formation breakdown pressure at the point under consideration minus the hydrostatic head of the mud/or influx in the casing. During well control operations the critical point to consider is the casing shoe.
MAASP = Formation BreakDown Pressure - Head of mud in use
or
MAASP = (E.M.W - MWMUD) x 0.052 x Shoe Depth (TVD)
Where
E.M.W = Equivalent mud weight at which formation breaks at shoe . . .