Abstract: Method of completing an uncased section (10) of a borehole (1) in an underground formation (2) comprising the steps of:(a) placing at a predetermined position in the borehole (1) a slotted liner (11) provided with overlapping longitudinal slots (12);(b) fixing the upper end of the slotted liner (11); and(c) moving upwardly through the slotted liner (11) an upwardly tapering expansion mandrel (15) having a largest diameter which is larger than the inner diameter of the slotted liner (11).

Abstract: A method of creating a wellbore in an underground formation is provided. A borehole is drilled in the underground formation, whereafter a casing of a ductile material is lowered into the borehole. The casing is selected to have a smaller elastic radial deformation than the surrounding formation when the casing is radially expanded against the borehole wall by application of a radial force to the casing. Said radial force is applied to the casing so as to radially expand the casing against the borehole wall thereby inducing a plastic radial deformation of the casing and an elastic radial deformation of the surrounding underground formation, whereafter the radial force is removed from the casing.