Primary barrier protecting the A annulus from SCP

An IOC in Malaysia had a requirement for a life of well solution to protect the A annulus from gas migration / Sustained Casing Pressure (SCP) within a high pressure, gas producing, cemented mono bore application.

Initial designs considered cement to surface. However. uncertainty was recognized regarding the ability of the cement to seal against gas pressure due to micro annulus, along with the reliability of the cement integrity over life of well.

The solution was installed as a 4 ½ in. mono bore completion incorporating one x V0 812WAB to be set within the 9 5/8 in. casing. The top of cement was brought to 300 m inside the 9 5/8 in. shoe, and the V0 812WAB was positioned standalone, 250 m above top of cement.

The initial design was to expand the V0 812WAB within the cement, providing cement assurance. Further review recognized the benefits of setting the Welltec Annular Barrier® (WAB) shallow of the cement, enabling a contingency expansion against cured cement in the event the float shoe did not seal.

The V0 812WAB was qualified in accordance with IS0 14310 using the V0 leak criteria to a delta P of 7,500 psi. The 7,500 psi capability was required to seal against possible trapped pressure from top of cement to the WAB.

The robust nature of the WAB enabled casing rotation during cementing. The WAB was quickly expanded upon bumping the cement plug, while under full surface control.

Sealing integrity of the WAB was verified via an annular pressure test, fully meeting the primary well barrier requirements.