SPE 177633 - NOVEL APPROACH TO COMBAT THE B ANNULUS PRESSURE BUILD-UP CHALLENGE
In December 2014 a metal annular packer equipped with sealing elastomers, was installed and verified in an offshore platform well in Norway. The annular packer was installed to function as a barrier element against pressure buildup from shallow formations in the overburden with limited flow potential, containing liquid only (no gas). The packer was installed between the intermediate casing and the production casing.
Upfront the installation the packer was tested and qualified according to ISO 14310 V3. This paper describes the operation, which was a world’s first, as well as the implications this achievement has for the industry in terms of preventing the plague of sustained casing pressure (SCP).
SCP can be defined as pressure in any annulus that is measurable at the wellhead and rebuilds when bled down, not caused solely by temperature fluctuations or imposed by the operator.
The wells were facing B annulus pressure build-up. Studies revealed that it originated from shallow formations in the overburden. A project team was challenged to investigate find and verify a barrier for the 9 5/8’’ x 13 3/8’’ annulus.
The initial, two main methods attempted were second stage cementing and long primary cement jobs. Second stage cementing had operational limitations while long primary cement jobs were subject to narrow ECD margins. Alternative methods were evaluated because of these challenges and the concept of the metal packer was considered being the most suitable option.