Subterranean well and formation treatment

Abstract

a. A polymetaphosphate composition and method for temporarily sealing a well formation in a wellbore to facilitate a treatment therein and a well tool which can include a flow path, and a flow blocking device which selectively prevents flow through the flow path. The well tool can include a polymetaphosphate composition. A method of constructing a downhole well tool can include forming a structure of a solid mass comprising a polymetaphosphate composition, and incorporating the structure into the well tool.

What is claimed is: 
     
         1 . A method of plugging in a well formation adjacent or near a wellbore in a subterranean formation comprising:
 a. flowing down said casing a wellbore fluid having dispersed therein a plurality of substantially spherical high strength degradable compositions being sized to seal said perforations and being comprised of polymetaphosphates of the formula
   AXH2P04.2H20+BMO+2(NH4)2HPQ4->(1/ n )[XM(P03)3] n +ammonia+water 
   
       wherein A and B are numbers of moles of reactants and the ratio of A:B is in the range of from about 1:1 to about 6:1, X is selected from Li, Na or K, M is selected from Be, Mg, Ca, Zn, Pb, Cu or Ni and n is from about 1 to about 100 or greater; and continuing the flow of said wellbore fluid until at least a portion of said perforations are sealed by said structures. 
     
     
         2 . The method of  claim 1  wherein said high strength structure has a coating of a polymer selected from the group consisting of polylactide, crosslinked polylactide, polyglycolide, crosslinked polyglycolide and mixtures thereof. 
     
     
         3 . The method of  claim 1  wherein said high strength structures are substantially spherical with a diameter greater than one-quarter inch. 
     
     
         4 . The method of  claim 1  wherein X is Na and M is Ca or Mg. 
     
     
         5 . The method of  claim 4 , wherein the structure has a barrier coating which at least temporarily prevents the polymetaphosphates from hydrating. 
     
     
         6 . The method of  claim 4 , wherein the barrier comprises a polymer selected from the group consisting of polylactide, crosslinked polylactide, polyglycolide, crosslinked polyglycolide and mixtures thereof. 
     
     
         7 . The method of  claim 4 , wherein the barrier prevents hydrating of the polymetaphosphates composition until after the well tool is installed in the wellbore. 
     
     
         8 . The method of  claim 5 , wherein a pressure differential is applied across the structure prior to the barrier permitting the anhydrous boron compound to hydrate. 
     
     
         9 . The method of  claim 5 , wherein the barrier dissolves in an aqueous fluid at a rate slower than a rate at which the polymetaphosphate composition dissolves in the aqueous fluid. 
     
     
         10 . The method of  claim 4  wherein X is Na and M is Ca or Mg.