Well Treatment

Abstract

The present invention provides a method for the treatment of a subterranean formation which contains sand particles, said method comprising contacting said formation with a material capable of increasing the residual matrix strength of said particulate fine whereby to reduce or prevent their migration whilst minimizing any decrease in their permeability. Preferred materials include organosilanes and enzyme systems.

1 .- 24 . (canceled) 
     
     
         25 . A method for the treatment of a subterranean formation which comprises sand particles, the method comprising contacting the formation with a material capable of increasing the residual matrix strength of the sand particles whereby to reduce or prevent their migration whilst minimizing any decrease in the permeability of the formation, wherein the material is produced by an enzyme system which comprises an enzyme and a substrate therefor. 
     
     
         26 . The method of  claim 25 , wherein the material is capable of imparting a residual matrix strength to the sand particles in the range of 0.1 bar to 500 bar. 
     
     
         27 . The method of  claim 26 , wherein the material is capable of imparting a residual matrix strength to the sand particles in the range of 1 bar to 200 bar. 
     
     
         28 . The method of  claim 25 , wherein the material, on contact with the sand particles, effects a reduction in permeability of the formation of less than 40%. 
     
     
         29 . The method of  claim 28 , wherein the material, on contact with the sand particles, effects a reduction in permeability of the formation of less than 30%. 
     
     
         30 . The method of  claim 25 , wherein the material is capable of increasing the residual matrix strength of the sand particles by 20% to 1,000%, without decreasing the permeability of the formation by more than 50% to 1% 
     
     
         31 . The method of  claim 30 , wherein the material is capable of increasing the residual matrix strength of the sand particles by 100% to 200%. 
     
     
         32 . The method of  claim 30 , wherein the material is capable of increasing the residual matrix strength of the sand particles without decreasing the permeability of the formation by more than 30% to 1%. 
     
     
         33 . The method of  claim 25 , wherein the enzyme system comprises a urease. 
     
     
         34 . The method of  claim 33 , wherein the enzyme system comprises a urease in combination with urea. 
     
     
         35 . The method of  claim 33 , wherein the urease is isolated from Jack bean. 
     
     
         36 . The method of  claim 35 , wherein the urease is Urease Canavalia ensiformis. 
     
     
         37 . The method of  claim 33 , wherein the urease enzyme is in combination with urea and wherein the method further comprises the use of an aqueous solution containing a salt of calcium. 
     
     
         38 . The method of  claim 37 , wherein the salt of calcium is calcium chloride. 
     
     
         39 . The method of  claim 25 , wherein the enzyme and the substrate therefor are employed in an amount of from 5 to 300 I.U./cm 3 . 
     
     
         40 . The method of  claim 39 , wherein the enzyme and the substrate therefor are employed in an amount of less than 100 I.U./cm 3 . 
     
     
         41 . The method of  claim 25 , wherein the enzyme system is applied as a dispersion or solution in a substantially anhydrous hydrocarbon carrier. 
     
     
         42 . A method for the treatment of a subterranean formation which comprises sand particles, the method comprising:
 (i) pre-flushing the formation whereby to remove substantially all water from the pore space or voids of the formation;   (ii) contacting the formation with an enzyme system which comprises an enzyme and a substrate therefor, wherein the system produces a material capable of increasing the residual matrix strength of the sand particles; and   (iii) optionally after-flushing the formation.   
     
     
         43 . The method of  claim 42 , wherein the enzyme system comprises a urease. 
     
     
         44 . The method of  claim 42 , wherein the material is capable of imparting a residual matrix strength to the sand particles in the range of 0.1 bar to 500 bar. 
     
     
         45 . A hydrocarbon well treatment composition comprising a carrier liquid comprising an enzyme system which comprises an enzyme and a substrate therefor, wherein the system produces a material capable of increasing the residual matrix strength of sand particles contained within a subterranean formation whereby to reduce or prevent their migration whilst minimizing any decrease in the permeability of the formation. 
     
     
         46 . The composition of  claim 45 , wherein the enzyme system comprises a urease. 
     
     
         47 . The composition of  claim 45 , wherein the material is capable of imparting a residual matrix strength to the sand particles in the range of 0.1 bar to 500 bar.