Maximum Allowable Annular Surface Pressure (MAASP) is the maximum annular pressure which will cause formation break down. MAASP can be in a static condition and a dynamic condition (circulating).

At the static condition, MAASP will be same as MISICP and the equation is listed below;

MAASP, psi = (Leak Off Test pressure, ppg – current mud weight, ppg) x 0.052 x Casing shoe TVD, ft

At the dynamic condition, due to friction pressure in the annulus while circulating, it is very difficult to calculate an accurate MAASP therefore it is not recommended to determine the dynamic MAASP while circulating the kick out of the well. Furthermore, you should NOT use MASSP at the static condition while circulating. For example, you determine the static MASSP of 1000 psi and while circulating, casing pressure can go more than 1000 psi. If you try to lower the casing pressure down by misleading the interpretation of this value, the additional kick will go into the well and finally it will make the well control situation even worse.

Example: 9-5/8” casing was set at 8,500MD/8,000’TVD.

9-5/8” casing : L-40, 43.5 lb/ft, burst pressure = 6,330 psi, collapse pressure =3,810 psi

Leak off test at 9-5/8” casing shoe = 15.0 ppg equivalent mud weight

Current hole depth is 12,000’MD/10,000’TVD and current mud weight is 10.0 ppg

20% de-rate burst pressure