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Well: Knarr A-3H

Operation type: installing lower and upper completions

Well: infill well

Reservoir: depleted (tight pressure margins)

Conditions: moderate

Trajectory: J-type

Location: Knarr field, North Sea

Rig: Deepsea Bergen (Aker H-3)

Case: dynamic rig heave limit calculated during well planning and utilized in well operations

“Simulations from Heavelock Solutions allowed us to increase our rig heave limit for running of lower completions in Knarr A-H3 well by one meter. This saved us at least 24 hours of weather-related NPT and paid back the simulations many times over. Conducting tailor-fit rig heave simulations gave the well team increased confidence in how the operations could be conducted in safest possible manner. This is a best practice we would like to use also in the future.”

- Knut Hals, Completions and Well Interventions Team Lead

- Norske Shell

Shell Knarr A-3H


Planned commencement for completions in March (winter conditions) and concern for swab and surge was flagged high in the risk register. Accurate weather criteria required to de-risk operations and optimize uptime to reduce NPT/WOW and hence costs (marginal project).

Lower Completion to be run with SAS, swell packer and glass plug (closed end)

Swab and surge risks identified:

  • Cause breach of frac formation pressure

  • Risk of losses/kick

  • Well damage => production impact

Swab screen hanger packer elements (NPT)

  • Getting stuck

  • Pull completion

Upper Completion to be run with packer, PDHG and TRSSSV

Swab production packer elements (NPT)

  • Getting stuck

  • Pull completion


Initial meeting convinced Norske Shell that Heavelock Solutions had a very good business case - to utilize tailor-fit surge & swab simulations that would take into account rig heave motion, well trajectory, well fluids, weather data at location, completion components, casing and well fluids.


Advanced surge & swab simulations provided a tailored and fit for purpose weather criteria that reduced risk for getting stuck, damaging reservoir as well as potentially massive NPT related to Waiting On Weather (WOW).


An increase in Lower Completion heave limit with almost 1.0 m saved Norske Shell for approximately a day of WOW-related downtime.


Dynamic rig heave simulations and the solid work to define the weather criteria will also be evaluated by Norske Shell for future completion operations as they see a massive potential for savings with this approach. Tailor-made dynamic rig heave limit simulations reduce overall project risk and help avoiding generic recommendations.

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