PROJECT PROFILE

Collapsed Well (Surface Casing Primary Structural Support Member)

Routine inspections by the Operator & Regulatory Authorities did not report any issues with this flowing well.
In subsequent inspections, MADCON technicians discovered subtle, tell-tale signs of a collapsed surface casing.

Well was supported with engineered, rigless design. (A section of engineered support device can be seen in the top right photo of the picture below.)
Removal of the conductor revealed a totally corroded section of surface casing.

Surface casing and conductor were restored to full structural integrity and the well was brought back to full production utilizing MADCON’s patented repair methods.
With this type of well design, the surface casing is the primary structural member supporting the well. The conductor is not designed to carry axial load, but to provide protection for the inner casings from lateral bending moment in heavy wave loads.
The root cause of the failure of the surface casing was due to the conductor to surface casing annulus being open to atmosphere which allowed active (but hidden) corrosion of the surface casing to the point of collapse.
Grouting and/or sealing the conductor to surface casing annulus is critical in preventing active corrosion of the surface casing and interior of the conductor.