Additive For Reducing Torque On A Drill String

Abstract

A method of reducing the torque of a drill string used in drilling a subterranean well that includes injecting into the drilling fluid a composition including a base fluid and a polymer coated colloidal solid material. The polymer coated colloidal solid material includes: a solid particle having an weight average particle diameter (d 5 o ) of less than ten microns, and a polymeric dispersing agent coated onto the surface of the solid particle during the cominution (i.e. grinding) process utilized to make the colloidal particles. The polymeric dispersing agent may be a water soluble polymer having a molecular weight of at least 2000 Daltons. The solid particulate material may be selected from materials having of specific gravity of at least 2.68 and preferably the solid particulate material may be selected from barium sulfate (barite), calcium carbonate, dolomite, ilmenite, hematite, olivine, siderite, strontium sulfate, combinations and mixtures of these and other similar solids that should be apparent to one of skill in the art.

1 . A lubricating composition comprising a base fluid and a polymer coated colloidal solid material, wherein the polymer coated colloidal solid material includes: a plurality of solid particles having a weight average particle diameter (d 50 ) of less than ten microns; and a polymeric dispersing agent absorbed to the surface of the solid particles. 
     
     
         2 . The composition of  claim 1 , wherein the base fluid is an aqueous fluid or an oleaginous fluid. 
     
     
         3 . The composition of  claim 1 , wherein the base fluid is selected from, water, brine, diesel oil, mineral oil, white oil, n-alkanes, synthetic oils, saturated and unsaturated poly(alpha-olefins), esters of fatty acid carboxylic acids and combinations thereof. 
     
     
         4 . The composition of  claim 1 , wherein the plurality of solid particles is selected from barium sulfate (barite), calcium carbonate, dolomite, ilmenite, hematite, olivine, siderite, strontium sulfate and combinations thereof. 
     
     
         5 . The composition of  claim 1 , wherein the plurality of solid particles have a weight average particle diameter (d 50 ) less than ten microns. 
     
     
         6 . The composition of  claim 1 , wherein greater than 25% of the plurality of solid particles have a diameter less than 2 microns. 
     
     
         7 . The composition of  claim 1 , wherein the plurality of solid particles are composed of a material having a specific gravity of at least 2.68. 
     
     
         8 . The composition of  claim 1 , wherein the polymeric dispersing agent is a water soluble polymer of molecular weight of at least 2,000 Daltons. 
     
     
         9 . A lubricating composition comprising a base fluid and a polymer coated colloidal solid material, wherein the polymer coated colloidal solid material includes: a plurality of solid particles wherein less than 10% of the solid particles have a diameter greater than 10 microns; and a polymeric dispersing agent absorbed to the surface of the solid particles. 
     
     
         10 . The composition of  claim 9 , wherein the base fluid is an aqueous fluid or an oleaginous fluid. 
     
     
         11 . The composition of  claim 9 , wherein the base fluid is selected from, water, brine, diesel oil, mineral oil, white oil, n-alkanes, synthetic oils, saturated and unsaturated poly(alpha-olefins), esters of fatty acid carboxylic acids and combinations thereof. 
     
     
         12 . The composition of  claim 9 , wherein the plurality of solid particles is selected from barium sulfate (barite), calcium carbonate, dolomite, ilmenite, hematite, olivine, siderite, strontium sulfate and combinations thereof. 
     
     
         13 . The composition of  claim 9 , wherein the plurality of solid particles have a weight average particle diameter (d 50 ) less than ten microns. 
     
     
         14 . The composition of  claim 9 , wherein greater than 25% of the plurality of solid particles have a diameter less than 2 microns. 
     
     
         15 . The composition of  claim 9 , wherein the plurality of solid particles are composed of a material having a specific gravity of at least 2.68. 
     
     
         16 . The composition of  claim 9 , wherein the polymeric dispersing agent is a water soluble polymer of molecular weight of at least 2,000 Daltons. 
     
     
         17 . A lubricating composition comprising a base fluid and a polymer coated colloidal solid material, wherein the polymer coated colloidal solid material includes:
 a plurality of solid particles, wherein at least than 90% of the solid particles have a diameter less than 10 microns; and a polymeric dispersing agent absorbed to the surface of the solid particles, wherein the polymeric dispersing agent is a water soluble polymer of molecular weight of at least 2,000 Daltons.   
     
     
         18 . The composition of  claim 17 , wherein the plurality of solid particles is selected from barium sulfate (barite), calcium carbonate, dolomite, ilmenite, hematite, olivine, siderite, strontium sulfate and combinations thereof. 
     
     
         19 . The composition of  claim 17 , wherein greater than 25% of the plurality of solid particles have a diameter less than 2 microns. 
     
     
         20 . The composition of  claim 17 , wherein the plurality of solid particles are composed of a material having a specific gravity of at least 2.68. 
     
     
         21 . A method of reducing the torque in a rotating drill string component, the method comprising: injecting into the drilling fluid a composition including a base fluid, and a polymer coated colloidal solid material, wherein the polymer coated colloidal solid material includes: a solid particle coated with a polymeric dispersing agent absorbed to the surface of the solid particle.