Patent ID: 7490676

Claim:
Method for casing a well where after each drilling phase to a predetermined depth, a string of metal casing ( 6 , 6 ′) is run into the well, each successive metal casing being lowered through the previously run preceding casing ( 5 , 5 ′) and the top end ( 26 ) from the next casing being connected in a sealed way with said preceding casing ( 5 , 5 ′); the method involves the following steps: a) running a next casing ( 6 , 6 ′) through a preceding casing ( 5 , 5 ′) having a common diameter, where said next casing ( 6 , 6 ′) has a largest transverse dimension smaller than the internal diameter of said preceding casing ( 5 , 5 ′), the top end ( 26 ) of said next casing being secured to a drillstring ( 54 ); b) positioning the top end ( 26 ) of said next casing ( 6 , 6 ′) in the vicinity of a previously inflated bottom bell ( 28 ) of the preceding casing ( 5 , 5 ′), said bottom bell having an inner diameter larger than said common diameter; c) expanding the diameter of said next casing ( 6 , 6 ′) so that the diameter of said next casing ( 6 , 6 ′) is equal to said common diameter; and d) establishing a sealed connection between the top end ( 26 ) of said next casing ( 6 , 6 ′) and bottom end ( 28 ) of said preceding casing ( 5 , 5 ′).