A 60-year old well in the Chadar field, Libya was exhibiting a leak at surface and sustained pressure in all three annuli – A, B and C. The age of the well coupled with the symptoms suggested a complex multi-barrier failure scenario that needed to be diagnosed quickly and accurately so that the well could be secured safely.

The customer selected TGT’s ‘Multi Seal Integrity’ diagnostic product to locate the source of pressure and associated flowpaths. Multi Seal Integrity diagnostics are delivered using TGT’s proprietary True Integrity system, leveraging a combination of key technology platforms applied by diagnostic experts using a methodical workflow. In particular, Chorus acoustic and Indigo multisense technology were utilised to precisely locate seal failures and associated flowpaths throughout the well system, from the reservoir, through barriers to the wellbore.

The critical first step in applying the True Integrity system involves developing a customised diagnostic programme that would ’stress-test’ the well whilst Chorus and Indigo sensors recorded the resulting well dynamics downhole. Data acquired during the programme was then processed and analysed by experts using a third platform, the Maxim digital workspace.

The diagnostic programme involved activating the well in four well state scenarios; one shut-in, and the others bleeding-off each of the three annuli.

The True Integrity system successfully identified the sources of pressure and revealed a highly-complex geometry of interconnected flowpaths between several formation layers and through multiple tube and cement barriers.

Equipped with a complete diagnosis, the operator was able to design and execute an appropriate P&A programme to secure the well permanently, eliminating any further risk to people and the planet.