Inspectahire have been working in partnership with Shell Global Solutions and RTD in developing Visual and Pulsed Eddy Current inspections of production wells in the UK North Sea sector to meet the growing demands well integrity monitoring and assessment.
Using small camera systems Inspectahire managed to get into the D Annulus of the production wells and find a path to the: HAT (Highest Astronomical Tide) LAT (Lowest Astronomical Tide).
First, a thorough access survey was carried out to see if there was a sufficient gap at the top of well between the surface casing and conductor (D Annulus), using small bullet cameras (can we name equipment?) to fluid/grout level. If no access is available due to starter head sitting on the conductor a hole cutting (100mm) into the conductor would have been required at two locations. A PEC Probe could then be deployed down the D annulus to measure wall thickness of the surface casing and conductor if required. A further test was developed over the years to test the integrity of the surface casing. Pressure was induced in the C annulus and cameras were lowered down the D annulus fluid level to observe. Lots of bubbles indicated large communication between annulus. Fewer bubbles indicated less communication. No bubbles and pressure build up in the C annulus indicated no communication.
The inspection was carried out during normal production conditions on the platform. Moving conductors and wells together with hot low level and high level pipe work within the well bay module. All three conductors were found to be completely sheared at the -10 support level at approximately -42 meters from the top of the conductor.
The North access was entered and the fluid level reached at 24m. Discarded umbilical cable was found at 14m from a previous inspection, due to a entrapment of a camera in the D-Annulus. No further damage to the conductor could be seen at this stage. The South access was not possible to inspect due to a grout hose and casing leaning against the conductor and causing restriction at 4 metres.
The North East access was restricted at 20 metres due to the discarded umbilical cable and grout hose in the D Annulus causing a snagging hazard. A centralizer was found to be broken at 14m, it was located within the North West access. The South West access was entered and the tear in the conductor wall reported from a previous inspection was noted at a depth of 15.5 metres. The fluid level was recorded at 24.5 metres. (Would be good to identify equipment and specialists/skills used in these procedures).
(Inspectahire used a range of techniques/equipment while carrying out a D annulus inspection. It is often the case that a push rod camera system is deployed. P374 • IS Camera System • Water Proof to110m • 25 mm LED Light Head • 60m GRP Rod on Coiler • Meter Counter)
A five year rolling program was completed in all Shell North Sea assets successfully and without any accidents or injury to personnel.