Shell Oil Comapny

Shell Internationale Research Maatschappij, B.v.

William Robert Portas

Djurre Hans Zijsling

Daniele Di Crescenzo

Darrell Scott Costa

A portion of a wellbore is drilled in a subterranean formation, using a drilling string () disposed within a casing string () and extending through a cement retainer () disposed within the casing string. The drilling string can be retracted into the casing string to a location fully above the cement retainer, and subsequently the casing string can be cemented in the wellbore whereby maintaining the drilling string inside the casing in the wellbore.

System and method for drilling a wellbore portion in a subterranean formation

The invention relates to a method for drilling and casing a wellbore using a drilling rig having a predetermined load capacity, using a casing scheme comprising two or more casing strings, and at least one combined casing string, which includes a first one of the casing strings fitting within a second casing string. The weight of the at least one combined casing string may exceed the load capacity of the drilling rig, and the weight of each of the parts of the at least one combined casing string is less than the load capacity.

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Gautier, MS, United States of America

William Robert Portas