Method of creating a zonal isolation in an underground wellbore

A method of creating a zonal isolation above a target zone in an underground wellbore comprises: inserting a slurry injection tubing into the wellbore; arranging within an annular space surrounding said tubing an particle accumulation means, such as an expandable screen or an area where the slurry velocity is reduced; and pumping a slurry comprising a carrier fluid and granular material down via the slurry injection tubing and the target zone and then up into the annular space, such that at least some granular material accumulates and forms an elongate zonal isolation in the annular space between the target zone and the particle accumulation means, which zonal isolation is removable and exerts a limited radial force to the surrounding formation, thereby reducing the risk of formation damage.