Completion Fluid for Reducing Friction Between Metal Surfaces

Abstract

A liquid mixture reduces the friction between two surfaces, at least one of which is moving with respect to the other such as tubing moving within the casing of an oil or gas well. The mixture includes an oil, a suspending agent, polymer particles and a surfactant.

We claim: 
     
         1 . A liquid mixture comprising:
 a dispersion of polymer particles in an oil phase, wherein the polymer particles are configured to reduce friction between metal surfaces;   a suspending agent; and   a surfactant, wherein the surfactant is configured to provide oil-wetting of the metal surfaces without forming a stable emulsion.   
     
     
         2 . The liquid mixture of  claim 1 , wherein the polymer particles are configured for transport by oil droplets. 
     
     
         3 . The liquid mixture of  claim 2 , wherein the oil droplets are attachable to the metal surfaces. 
     
     
         4 . The liquid mixture of  claim 1 , wherein the polymer particles are concentrated at the metal surfaces. 
     
     
         5 . The liquid mixture of  claim 1 , wherein the suspending agent comprises a colloidal suspension of ethylene bis-amide in oil. 
     
     
         6 . The liquid mixture of  claim 5 , wherein a concentration of the ethylene bis-amide is in a range from 3% to 7% by weight of the liquid mixture. 
     
     
         7 . The liquid mixture of  claim 5 , wherein the oil comprises a dispersion of water-soluble polymers. 
     
     
         8 . The liquid mixture of  claim 7 , wherein the water-soluble polymers comprise polyacrylamide. 
     
     
         9 . The liquid mixture of  claim 1 , wherein the suspending agent comprises fumed silica or organophilic clays. 
     
     
         10 . The liquid mixture of  claim 1 , wherein the polymer particles have a diameter ranging from 1 micron to 100 microns. 
     
     
         11 . A method for reducing friction between metal surfaces, the method comprising:
 adding polymer particles to an oil phase;   suspending the polymer particles in the oil phase with a suspending agent;   carrying the polymer particles in the oil phase; and   forming oil droplets.   
     
     
         12 . The method of  claim 11 , further comprising forming an oil film on the metal surfaces with a surfactant. 
     
     
         13 . The method of  claim 11 , further comprising carrying the polymer particles to an oil film. 
     
     
         14 . The method of  claim 11 , further comprising attaching the oil droplets to the metal surfaces. 
     
     
         15 . The method of  claim 11 , further comprising oil-wetting, with a surfactant, the metal surfaces without forming a stable emulsion. 
     
     
         16 . The method of  claim 11 , further comprising reducing friction between the metal surfaces. 
     
     
         17 . The method of  claim 11 , further comprising concentrating the polymer particles at the metal surfaces. 
     
     
         18 . The method of  claim 11 , wherein the suspending agent comprises a colloidal suspension of ethylene bis-amide in oil. 
     
     
         19 . The method of  claim 11 , wherein the polymer particles have a diameter ranging from 1 micron to 100 microns. 
     
     
         20 . The method of  claim 11 , wherein the suspending agent comprises fumed silica or organophilic clays.