During casing design operations there are product spaces generated between casings strings or between tubing and casing that are called annuli, it is the product as a result of design and not created purposely. The ideal case is these annuli must be filled with cement, but for some reasons such as limited cement technologies and weak formations, these annuli are filled with small-compressibility fluids (generally weighted mud, cement spacers, or transparent brines) to avoid fracturing of the weak formation and lost circulation during cementation. In high-pressure high-temperature wells (HPHT) these fluids will be heated during drilling operations and production activities by the fluids that coming from heat formations in the bottom of the well and as a result, it will expand and if the annulus was closed it will generate a trapped annulus pressure (TAP), it is the first type of annular pressure, this pressure can reach a very high value (10,000 - 12,000 psi or more).