CONSOLIDATION AND WELLBORE STRENGTH ENHANCEMENT WITH CaCO3 PRECIPITATION

Abstract

A method of treating a wellbore in a subterranean formation including introducing a first fluid into a formation, wherein the first fluid comprises: a first water soluble salt and a carrier; placing a second fluid into the formation, wherein the second fluid comprises: a second water soluble salt and a carrier, wherein the first fluid and second fluid produce a solid precipitate upon contact; and allowing the solid precipitate to form in-situ in the formation. An acid may be added to the wellbore after formation of the precipitate. The method may be also used for stabilizing a wellbore during drilling, and shutting off and reopening a region in a formation.

What is claimed is: 
     
         1 . A method of treating a wellbore in a subterranean formation comprising:
 introducing a first fluid into a formation, wherein the first fluid comprises a first water soluble salt and a carrier;   introducing a second fluid into the formation, wherein the second fluid comprises a second water soluble salt and a carrier, and wherein the first fluid and second fluid produce a solid precipitate upon contact; and   allowing the solid precipitate to form in-situ in the formation.   
     
     
         2 . The method of  claim 1 , wherein the first water soluble salt is selected from soluble calcium salts, soluble magnesium salts, soluble iron (II) salts, soluble iron (III) salts, and combinations thereof. 
     
     
         3 . The method of  claim 2 , wherein the first water soluble salt is selected from calcium chlorides, magnesium chlorides, ferrous chlorides, ferric chlorides, and combinations thereof. 
     
     
         4 . The method of  claim 1 , wherein the second water soluble salt is selected from soluble metal carbonates, soluble metal sulfates, soluble metal phosphates, soluble metal hydroxides, soluble metal silicates, soluble carbonates, soluble sulfates, soluble phosphates, soluble hydroxides, soluble silicates, and combinations thereof. 
     
     
         5 . The method of  claim 4 , wherein the second water soluble salt is selected from sodium carbonates, sodium sulfates, sodium phosphates, sodium hydroxides, sodium silicates, potassium carbonates, potassium sulfates, potassium phosphates, potassium hydroxides, potassium silicates, ammonium carbonates, ammonium sulfates, ammonium phosphates, ammonium hydroxides, ammonium silicates, and combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the second fluid is introduced into the formation before the first fluid is introduced into the formation. 
     
     
         7 . The method of  claim 1 , wherein the solid precipitate is selected from calcium carbonates, calcium sulfates, calcium phosphates, calcium hydroxides, calcium silicates, magnesium carbonates, magnesium phosphates, magnesium hydroxides, magnesium silicates, ferrous carbonates, ferrous phosphates, ferrous hydroxides, ferrous silicates, ferric carbonates, ferric phosphates, ferric hydroxides, ferric silicates, and combinations thereof. 
     
     
         8 . The method of  claim 1 , wherein the solid precipitate is formed on a surface of a material in the formation. 
     
     
         9 . The method of  claim 8 , wherein the material is selected from sandstone, carbonates, shale and combinations thereof. 
     
     
         10 . The method of  claim 8 , wherein the surface is selected from inner pores, exterior surfaces of the material, and combinations thereof. 
     
     
         11 . The method of  claim 10 , wherein the solid precipitate enhances the wellbore strength. 
     
     
         12 . The method of  claim 1 , further comprising deconsolidating the formation by introducing an acid into the formation upon formation of the solid precipitate. 
     
     
         13 . The method of  claim 12 , wherein the acid is introduced as at least one of a pill, a hydrolysable in-situ acid generator, and combinations thereof. 
     
     
         14 . The method of  claim 1 , wherein the carrier is selected from fresh water, sea water, brines containing at least one dissolved organic or inorganic salt, liquids containing water miscible organic compounds, and combinations thereof. 
     
     
         15 . A method for stabilizing a wellbore during drilling of said wellbore through a material selected from sandstone, carbonates, shale, and combinations thereof in a subterranean formation comprising a material selected from sandstone, carbonates, shale, and combinations thereof, said method comprising:
 pausing a drilling operation;   introducing a first fluid into a formation, wherein the first fluid comprises a first water soluble salt and a carrier;   introducing a second fluid into the formation, wherein the second fluid comprises a second water soluble salt and a carrier, and wherein the first fluid and second fluid produce a solid precipitate upon contact;   allowing the solid precipitate to form in-situ in the formation; and   continuing the drilling operation.   
     
     
         16 . The method of  claim 15 , wherein the first water soluble salt is selected from soluble calcium salts, soluble magnesium salts, soluble iron (II) salts, soluble iron (III) salts, and combinations thereof. 
     
     
         17 . The method of  claim 16 , wherein the first water soluble salt is selected from calcium chlorides, magnesium chlorides, ferrous chlorides, ferric chlorides, and combinations thereof. 
     
     
         18 . The method of  claim 17 , wherein the second water soluble salt is selected from soluble metal carbonates, soluble metal sulfates, soluble metal phosphates, soluble metal hydroxides, soluble metal silicates, soluble carbonates, soluble sulfates, soluble phosphates, soluble hydroxides, soluble silicates, and combinations thereof. 
     
     
         19 . The method of  claim 18 , wherein the second water soluble salt is selected from sodium carbonates, sodium sulfates, sodium phosphates, sodium hydroxides, sodium silicates, potassium carbonates, potassium sulfates, potassium phosphates, potassium hydroxides, potassium silicates, ammonium carbonates, ammonium sulfates, ammonium phosphates, ammonium hydroxides, ammonium silicates, and combinations thereof. 
     
     
         20 . The method of  claim 15 , wherein the solid precipitate is formed on a surface selected from sandstone, carbonates, shale and combinations thereof in the formation. 
     
     
         21 . The method of  claim 20 , wherein the surface is selected from inner pores, exterior surfaces of the material, and combinations thereof. 
     
     
         22 . A method of shutting off and reopening a region in a formation comprising a material selected from sandstone, carbonates, shale, and combinations thereof, said method comprising:
 introducing a first fluid into a region in the formation, wherein the first fluid comprises a first water soluble salt and a carrier;   introducing a second fluid into the region of the formation, wherein the second fluid comprises a second water soluble salt and a carrier, and wherein the first fluid and second fluid produce a solid precipitate upon contact;   allowing the solid precipitate to form in-situ in the region of the formation; and   introducing an acid into the region of the formation.   
     
     
         23 . The method of  claim 22 , wherein the first water soluble salt is selected from soluble calcium salts, soluble magnesium salts, soluble iron (II) salts, soluble iron (III) salts, and combinations thereof. 
     
     
         24 . The method of  claim 23 , wherein the first water soluble is selected from calcium chlorides, magnesium chlorides, ferrous chlorides, ferric chlorides, and combinations thereof. 
     
     
         25 . The method of  claim 22 , wherein the second water soluble salt is selected from soluble metal carbonates, soluble metal sulfates, soluble metal phosphates, soluble metal hydroxides, soluble metal silicates, soluble carbonates, soluble sulfates, soluble phosphates, soluble hydroxides, soluble silicates, and combinations thereof. 
     
     
         26 . The method of  claim 25 , wherein the second water soluble salt is selected from sodium carbonates, sodium sulfates, sodium phosphates, sodium hydroxides, sodium silicates, potassium carbonates, potassium sulfates, potassium phosphates, potassium hydroxides, potassium silicates, ammonium carbonates, ammonium sulfates, ammonium phosphates, ammonium hydroxides, ammonium silicates, and combinations thereof. 
     
     
         27 . The method of  claim 22 , wherein the solid precipitate is formed on a surface of the formation. 
     
     
         28 . The method of  claim 27 , wherein the acid is introduced as a pill, a hydrolysable in-situ acid generator, and combinations thereof. 
     
     
         29 . A wellbore treatment system comprising:
 an apparatus comprising a pump and a mixer to:   introduce a first fluid into a formation, wherein the first fluid comprises a first water soluble salt and a carrier;   introduce a second fluid into the formation, wherein the second fluid comprises a second water soluble salt and a carrier, wherein the first fluid and second fluid produce a solid precipitate upon contact;   allow the solid precipitate to form in-situ in the formation.