Patching of injection and production well annular casing leaks for

Abstract

A system of patching single and multiple casing leaks that occur in an injection well annulus, where there is direct communication from an outermost casing string to an original open-hole wellbore and adjacent earth strata. Preferred in this pumping system is a four-stage pump process employing four separate types of fluids. The first Injection Stage utilizes either H.sub.2 SiO.sub.3, Na.sub.2 in a solution of water forming Na.sub.2 SiO.sub.3 +H.sub.2 O (Sodium Metasilicate) or Na.sub.2 O*SiO.sub.2 (Sodium Silicate) in water. The second Injection Stage utilizes CaCl.sub.2 solution in water. These two solutions react in a double replacement chemical reaction to yield an aqueous phase and a solid phase. The third Injection Stage is then implemented, the same including a bentonite/high-density, high-solids, concentrated slurry additionally containing large plugging materials suspended therein. The Fourth Stage utilizes covalently bonded N.sub.2 in a gaseous state. After injection of the first Three Stages, N.sub.2 pressure is applied and the staged patching materials are moved into place at the casing hole(s), thread leak, packer leak, or perforation. Upon restriction, the materials react by the resulting combination and shear, at which point a filtration process begins. Filtration continues until the contents of all of the stages have completed their plating action and a tight impermeable seal is in place at the problem area.