Installing a Cameron Fontus™ configurable compact wellhead system as part of a major development in the North Sea supported achieving operator Equinor ASA’s goals for easier equipment handling and installation and optimized drilling efficiency, which in turn reduced rig time and HSE exposure. To date, four Fontus wellhead systems have been installed.
Equinor had two primary objectives related to wellhead systems for its development project: that the wellhead fit the platform configuration and would optimize drilling efficiency. SLB proposed installing a smaller, more compact 18 3/4-in wellhead with dual metal-to-metal (MTM) seals.
However, Equinor had three concerns from experience with the dual MTM seals of the wellhead used previously. The high axial setting load mandates a high tooling pressure with safety implications on the rig floor for setting, installation is complex and requires precise hose management, and workovers are complicated operations. In addition, installation of the production tubing hanger for these previous wellheads also required multiple rotations that adversely impacted drilling efficiency through NPT.
SLB configured an 18 3/4-in Fontus compact wellhead system with its proprietary next-generation MTM seal technology to address Equinor’s concerns. The compact design is 48% shorter than the previous wellhead system and also weighs one-third less to enable streamlining installation and operational safety. The similarly reduced height of the dual MTM seal assembly in turn enables a reduction in the height of the casing and production tubing hangers.
Equipment installation for the Fontus wellhead system reduced the time required for the previous wellhead system installation by about one-third. This improvement in drilling efficiency saved appreciable rig time. The majority of the time savings was delivered by running and locking in the 20-, 14-, and 10 3/4-in casing hangers in a single trip to reduce total trips by 3 and wellhead installation time by about 11 hours. Reengagement of the Fontus system’s stab-type running tool on the control line bushing also eliminates rotation from tubing hanger setup.
The installation simplicity of the 18 3/4-in dual MTM seal assembly for the Fontus wellhead system efficiently resolved the challenges Equinor had experienced. The average axial load was cut by half and the pressure through the tool for setting was reduced by one-third to pose less risk during operations on the rig floor. Only 15 metric tons of pull was needed to retrieve the dual MTM seal assembly in comparison to up to 50 t required for the previous version.
Furthermore, the push-fit installation of the dual MTM seal assembly as part of the Fontus system requires zero rotations to eliminate the NPT risk that rotation poses to hydraulic lines from twisting, damaging, and disconnecting them.
The reductions in platform size, rig time, and HSE exposure enabled by the advanced design and compact nature of the Fontus wellhead system and its dual MTM seal assembly have resulted in Equinor installing four Fontus wellhead systems to date as a crucial part of this major development.
