Method of treating oil and gas wells

Abstract

A two step process for treating an oil or gas well. The first step uses a cross linking agent, such as borax, as a preliminary wash for the well following drilling. The cross linking agent cleans the well of excess mud and pre-coats the tubing and the formation surfaces with the cross linking agent. The second step introduces a cement-polymer mixture into the well. A polymer, such as for example polyvinyl alcohol, that undergoes cross linking when exposed to the cross linking agent is employed. When the polymer comes into contact with the cross linking agent in the well, cross linking of the polymer occurs. This cross linking helps to prevent fluid loss into the formation. Also, because the cross linking agent wash previously cleaned the surfaces of the tubing and the formation, better bonding between the cement and the surfaces of the tubing and the formation occurs.

1 .- 14 . (canceled) 
     
     
         15 . A method for inhibiting fluid loss from an oil and gas well, said method comprising the steps of, separately: washing a well borehole with a wash composition, said wash composition comprising a cross linking agent, wherein said cross linking agent at least partially impregnates a formation's face and pumping a cement mixture into said well's borehole to cement at least a portion of a formation face, said cement mixture comprising a polymer composition, wherein said polymer polymerizes in, on, or about said formation's face upon exposure to said cross linking agent, thereby inhibiting fluid loss from said well's borehole to said formation. 
     
     
         16 . The method of  claim 15 , wherein the step of washing at least partially cleans the well of excess mud. 
     
     
         17 . The method  claim 15 , wherein the step of washing at least partially impregnates at least one of said borehole's tubing and said borehole's formation face with said cross linking agent. 
     
     
         18 . The method of  claim 15 , wherein said cross linking agent is added to said well borehole along with an oil-based drilling mud or “spacer”. 
     
     
         19 . The method of  claim 15 , wherein said cross linking agent is at least one of borax, boric acid, water soluble borates, sodium borates, calcium borates, potassium borates, titanates, zirconates, and mixtures thereof. 
     
     
         20 . The method of  claim 15 , further comprising the step of: adding fine particulate material to the polymer composition prior to mixing it with the cement mixture. 
     
     
         21 . The method of  claim 20 , wherein the fine particulate material is calcium carbonate. 
     
     
         22 . The method of  claim 15 , wherein the polymer is at least one of polyvinyl alcohol or a low viscosity partially hydrolyzed polyvinyl alcohol such as DuPont Elvanol(R) 51-05S8. 
     
     
         23 . A method for inhibiting fluid loss from an oil or gas well, said method comprising the steps of, separately: washing a well with a reactant agent that creates a thickened reaction product when a secondary mixture is encountered, and adding secondary mixture to the well's borehole which forms a thickened reaction product upon exposure to said reactant, thereby inhibiting fluid loss from said well's borehole to a formation adjacent to said well borehole. 
     
     
         24 . The method of  claim 15 , wherein the step of washing is removed and said cross linking agent is included with a drilling fluid circulated in said well's borehole prior to adding said cement mixture. 
     
     
         25 . A kit for inhibiting fluid loss from an oil and gas well comprising: a wash composition, said wash composition comprising a cross linking agent and a polymer composition, wherein said polymer polymerizes in, on, or about a formation's face upon exposure to said cross linking agent, thereby inhibiting fluid loss from said well's borehole to said formation through said formation's face. 
     
     
         26 . A polymerized well borehole, said polymerized well borehole formed by a method of  claim 15 . 
     
     
         27 . A method for reducing an amount of fluid loss additive necessary to inhibit fluid loss from an oil and gas well, said method comprising the steps of, separately: washing a well borehole with a wash composition, said wash composition comprising a cross linking agent, wherein said cross linking agent at least partially impregnates a formation's face and pumping a cement mixture into said well's borehole to cement at least a portion of a formation face, said cement mixture comprising a polymer composition, wherein said polymer polymerizes in, on, or about said formation's face upon exposure to said cross linking agent, thereby inhibiting fluid loss from said well's borehole to said formation through said formation's face, wherein between about 0.1% and about 90% by volume of a contemporary fluid loss additive is used to inhibit fluid loss. 
     
     
         28 . The method of  claim 27 , wherein said fluid loss additive's components are the same as the components of the contemporary fluid loss additive. 
     
     
         29 . The method of  claim 27 , wherein the step of washing is removed and said cross linking agent is included with a drilling fluid circulated in said well's borehole prior to adding said cement mixture. 
     
     
         30 . The method of  claim 15 , wherein said cement mixture comprises a permeable, micro-cluster silica material present in an amount from about 10 percent to about 30 percent by weight of the cement mixture, wherein said permeable, micro-cluster silica material has an average particle size ranging from about 30 to about 80 microns and a range of distribution from about 1 micron to about 200 microns. 
     
     
         31 . The kit of  claim 25 , further comprising: a permeable, micro-cluster silica material, wherein said permeable, micro-cluster silica material has an average particle size ranging from about 30 to about 80 microns and a range of distribution from about 1 micron to about 200 microns. 
     
     
         32 . The method of  claim 23 , wherein the step of washing is removed and said cross linking agent is included with a drilling fluid circulated in said well's borehole prior to adding said cement mixture. 
     
     
         33 . A polymerized well borehole, said polymerized well borehole formed by a method of  claim 23 . 
     
     
         34 . The method of  claim 23 , wherein said cement mixture comprises a permeable, micro-cluster silica material present in an amount from about 10 percent to about 30 percent by weight of the cement mixture, wherein said permeable, micro-cluster silica material has an average particle size ranging from about 30 to about 80 microns and a range of distribution from about 1 micron to about 200 microns. 
     
     
         35 . The method of  claim 27 , wherein said cement mixture comprises a permeable, micro-cluster silica material present in an amount from about 10 percent to about 30 percent by weight of the cement mixture, wherein said permeable, micro-cluster silica material has an average particle size ranging from about 30 to about 80 microns and a range of distribution from about 1 micron to about 200 microns.