Management of Sustained Casing Pressure in Offshore Gas Wells by a Novel Casing-Surface Design that Suppress Gas Migration at the Casing-Cement Interface

摘要

Sustained Casing Pressures (SCP) is still a serious problem that challenges the offshore producing gas wells. Despite existence of the many methods to mitigate it, SCP is still bringing severe health, safety and environmental (HSE) concerns necessitating the need for new methods. This article brings a new method of mitigating SCP caused by micro-annulus in offshore gas wells by designing a novel casing surface that will increase the length of casing-cement interface (CCI) for the same planned cement column length and thereby suppressing fluid migration through the CCI. Two new casing-surface designs were invented and tested by inputting the field data from offshore gas well X in conjunction with an existing SCP prediction model to verify the validity of the new method. The new developed method was found to have a great potential of controlling SCP and improve the production life time of the offshore gas wells by suppressing gas migration through micro-annulus.