Methods of forming packs in a plurality of perforations in a casing of a wellbore

The invention provides a method of forming packs in a plurality of perforations in a casing of a wellbore, the method comprising the steps of: (a) forming a plug of a plugging particulate material in the wellbore of the casing, wherein the plug covers at least one perforation in the casing; (b) forming a pack of a first packing particulate material in at least one perforation located above the plug in the casing; (c) removing at least an upper portion of the plug to expose the at least one perforation in the casing that had been previously covered by at least the upper portion of the plug; and (d) forming a pack of a second packing particulate material in the at least one perforation exposed by removing at least the upper portion of the plug, wherein the second packing particulate material can be the same or different from the first packing particulate material.