Abstract: A method for improving zonal isolation between formations along a borehole, comprises a) providing a pipe in the borehole, wherein at least a portion of the pipe lies between the formations, b) providing a body of cement in the annulus between the borehole wall and said pipe portion, c) allowing the body of cement to cure until it has reached at least 70 Bearden units consistency, and d) expanding said pipe portion so as to decrease the cross-sectional area of the annulus between the borehole wall and said pipe portion.

Abstract: A method for expanding an expandable tubular in a borehole, comprising the steps of: a) positioning the expandable tubular at a desired position in the borehole; b) anchoring the tubular at the desired position solely by means of a first cement portion in the annulus between the tubular and the borehole wall; c) expanding the tubular by moving an expansion device through the tubular. The cement may be cured or not cured when step c) is carried out and may or may not fracture during step c). The method may include providing an exit path for water expelled from the cement during expansion, providing a second cement portion having a longer cure time than the first cement portion, or calculating the length of cement that is required to anchor, based on the properties of the cement and the expected expansion force.