MAASP (Maximum Allowable Annulus Surface Pressure) is very important to know not to fracture the formation at the casing shoe. In case of a Sustained Casing Pressure in Casing Annulus this pressure needs to be calculated based on the fluid level in annulus.

To be able to use this calculator following information needs to be obtained:

- Surface Pressure in psi: direct reading from the pressure gauge,
- Gas Specific Gravity in SG if there is gas in annulus,
- Fluid depth in meter below gas column:
- Surface Temperature in Centigrade:
- Temperature at fluid level below gas:
- Casing Shoe depth where formation is concerned to be fractured.
- Density of the fluid in SG below gas column:
- Formation Frac Density in SG:

The calculations does not include any safety factor.