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We are looking to cut and pull old 9-5/8" casing from several platform wells in the North Sea.
The wells were constructed back in the days when it was normal practice to cement casing strings up inside the previous casing shoe, however, the actual top of cement is a little vague as 9-5/8" cement records are incomplete (unknown losses) and the CBL logs are typically inconclusive. There is OBM with 25% solids left behind the casings and the casings have been landed with a Vetco slip-and-seal type hanger.

The million dollar question is at what depth could we reasonably expect to be able to retrieve 9-5/8" casing strings from these wells?

Any guidance / experience on the cutting and pulling of 9-5/8" casings and the retrieval of Vetco slip-and-seal hangers thru the BOPs would be greatly appreciated.