Well Construction & Decommissioning: Tapered Casing strings run as liners

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Well Construction & Decommissioning: Tapered Casing strings run as liners

Dear colleagues

I am throwing out a request to gain knowledge and support to my internal and external networks.

We are engaged in and abandonment and decommissioning campaign in the Caspian Sea.

The wells were drilled in the former Soviet Union times by the Russians. The well were drilled in the 70’s and there are a number of interesting challenges to overcome. Not least in understanding how these wells were designed and constructed.

From the translation of old drilling reports, they were running tapered casing strings 10-¾” x 9-⅝” . Running the deeper 9-⅝” sections on drill pipe and then cementing in place; the upper 10-¾” sections were then run, cemented and then connected somehow to the lower section.

If anybody has experience of this and can help me understand the connection process whether it would be overshot, stabbed in or even rotated to form the connections.

If anybody can educate me on this it would be greatly appreciated.

Many thanks

John