Drill bit lubricant utilizing a sulfur-phosphorous EP agent

Abstract

A lubricant is shown and described. The lubricant includes about 1 to 15 weight percent of a sulfur-phosphorus extreme pressure agent, about 5 to 40 weight percent of a thickener, preferably a metal-complex soap, and a basestock. The basestock may be a mineral oil, a synthetic oil, or a combination thereof. Lubricant additives such as corrosion inhibitors, oxidation inhibitors, and anti-wear agents may also be added.

1 . A lubricant for a drill bit, comprising: 
 from about 1 to about 15 weight percent of a sulfur-phosphorus EP agent, wherein the sulfur-phosphorus EP agent comprises at least one selected from a substituted 1,3,4-thiadiazole, a sulfunized oxymolybdenum organo phosphorodithioate, sulfur-phosphorus ester amine salts, a zinc dithiophosphate, and combinations thereof.    from about 5 to about 40 weight percent of a thickener; and    a basestock.    
   
   
       2 . The lubricant of  claim 1 , wherein the sulfur-phosphorus EP agent comprises: 
 about 1 to about 5 weight percent of 1,3,4-thiadiazole-2( 3 H)-thione,5,5-dithiobis; and    about 1 to about 10 weight percent of molybdenum di(2-ethylhexyl)phosphorodithioate;    
   
   
       3 . The lubricant of  claim 1 , further comprising: 
 at least one additive selected from the group consisting of corrosion inhibitors, oxidation inhibitors, anti-wear agents, and zinc- and chlorine-based EP agents.    
   
   
       4 . The lubricant of  claim 1 , wherein the thickening agent is selected from at least one from the group consisting of a soap and a non-soap, wherein the soap includes soaps of calcium, aluminum, titanium, barium, lithium, and complexes thereof, and the non-soap includes urea, fine silica, fine clay, and silica gel.  
   
   
       5 . The lubricant of  claim 1 , wherein the combination of basestock comprises from 0 to 100% mineral oil and 100 to 0% synthetic oil, or any percentage therebetween.  
   
   
       6 . The lubricant of  claim 1 , further comprising from about 1 to about 10 weight percent of silica, about 5 to about 40 percent of a metal-complex soap by weight, and wherein the basestock comprises from 100 to 0% mineral oil and 0 to 100% synthetic oil, or any percentage therebetween.  
   
   
       7 . The lubricant of  claim 6 , further comprises from about 1 to about 10 weight percent of copper particles, about 1 to about 15 of molybdenum disulfide.  
   
   
       8 . The lubricant of  claim 7 , further comprising an ester-based swelling agent.  
   
   
       9 . A roller cone drill bit, comprising: 
 a bit body;    at least one leg extending downward from the bit body, wherein each leg has a journal and each journal has a bearing surface;    a roller cone mounted on each journal, wherein each roller cone has a bearing surface;    a grease reservoir in communication with the bearing surfaces; and    a lubricating composition in the grease reservoir and adjacent the bearing surfaces, the lubricating composition comprising: 
 from about 1 to about 15 weight percent of a sulfur-phosphorus EP agent, wherein the sulfur-phosphorus EP agent comprises at least one selected from a substituted 1,3,4-thiadiazole, a sulfunized oxymolybdenum organo phosphorodithioate, sulfur-phosphorus ester amine salts, a zinc dithiophosphate, and combinations thereof;  
 from about 5 to about 40 percent lubricant weight of a thickener;  
 and a basestock.  
   
   
   
       10 . The roller cone drill bit of  claim 9 , wherein the basestock comprises from 0 to 100% mineral oil and 100 to 0% synthetic oil, or any percentage therebetween.  
   
   
       11 . The roller cone drill bit of  claim 9 , further comprising: 
 an additive comprising at least one element selected from the group consisting of corrosion inhibitors, oxidation inhibitors, anti-wear agents, and zinc- and chlorine-based EP agents.    
   
   
       12 . The roller cone drill bit of  claim 9 , wherein the thickener is at least one selected from the group consisting of a soap and a non-soap, wherein the soap includes soaps of calcium, aluminum, titanium, barium, lithium, and complexes thereof, and the non-soap includes urea, fine silica, fine clay, and silica gel.  
   
   
       13 . A method for lubricating a roller cone drill bit, comprising: 
 providing a roller cone drill bit having a bit body, a grease reservoir, and at least one roller cone mounted on the bit body with at least one rotatable journal bearing; and    filling the grease reservoir with a lubricant, the lubricant comprising: 
 from about 1 to about 15 weight percent of a sulfur-phosphorus EP agent, wherein the sulfur-phosphorus EP agent comprises at least one selected from a substituted 1,3,4-thiadiazole, a sulfunized oxymolybdenum organo phosphorodithioate, sulfur-phosphorus ester amine salts, a zinc dithiophosphate, and combinations thereof;  
 from about 5 to about 40 percent lubricant weight of a thickener;  
 and a basestock.  
   
   
   
       14 . The method of  claim 13 , further comprising: 
 contacting the at least one journal bearing with the lubricant.    
   
   
       15 . The method of  claim 13 , wherein the basestock comprises from 0 to 100% mineral oil and 100 to 0% synthetic oil, or any percentage therebetween.  
   
   
       16 . The method of  claim 13 , wherein the lubricant further comprises an additive comprising at least one additive selected from the group consisting of oxidation inhibitors, corrosion inhibitors, anti-wear agents, and zinc- and chlorine-based EP agents.  
   
   
       17 . A method for drilling through an earth formation, comprising: 
 providing a roller cone drill bit having a bit body, a grease reservoir, and at least one roller cone mounted on the bit body with at least one rotatable journal bearing, wherein the grease reservoir contains a lubricant, the lubricant comprising: 
 from about 1 to about 15 weight percent of a sulfur-phosphorus EP agent, wherein the sulfur-phosphorus EP agent comprises at least one selected from a substituted 1,3,4-thiadiazole, a sulfunized oxymolybdenum organo phosphorodithioate, sulfur-phosphorus ester amine salts, a zinc dithiophosphate, and combinations thereof;  
 from about 5 to about 40 percent lubricant weight of a thickener;  
 and a basestock;  
   securing the drill bit to the end of a drill string; and    rotating the drill bit under an applied load on the earth formation.    
   
   
       18 . The method of  claim 17 , further comprising: 
 introducing the lubricating composition to the journal bearings.    
   
   
       19 . The method of  claim 17 , wherein the basestock comprises from 0 to 100% mineral oil and 100 to 0% synthetic oil, or any percentage therebetween.  
   
   
       20 . The method of  claim 17 , wherein the lubricating composition further comprises an additive comprising at least one additive selected from the group consisting of oxidation inhibitors, corrosion inhibitors, anti-wear agents, and zinc- and chlorine-based EP agents.