Creating zonal isolation between the interior and exterior of a well system

A method of creating zonal isolation between the exterior and interior of an uncased section of an underground well system which is located adjacent to a well section in which a well casing is present, the method comprising the steps of:

• inserting an expandable tubular through the existing well casing into the uncased section of the underground well system such that one end of the expandable tubular protrudes beyond the well casing into the uncased section of the well system and another end of the expandable tubular is located inside the well casing;
• and
• expanding the expandable tubular using an expansion mandrel having a conical surface, wherein the expandable tubular is made of a formable steel grade and is expanded by an expansion cone having a conical ceramic surface such that the one end is pressed towards wall of the uncased section of the well system and the outer surface of the other end is pressed against the inner surface of the well casing thereby creating an interference fit capable of achieving a shear bond and a hydraulic seal between the surrounding surfaces.