Emulsified drilling fluids and methods of making and use thereof

Abstract

Drilling fluids and methods of making and using drilling fluids are provided. The drilling fluid contains an aqueous phase, an oleaginous phase, and at least one surfactant having the formula R—(OC2H4)x—OH, where R is a hydrocarbyl group having from 8 to 20 carbon atoms and x is an integer from 1 to 10. Methods of producing drilling fluids include mixing an aqueous phase, an oleaginous phase, and at least one surfactant, and shearing the mixture. Methods of using drilling fluids to drill subterranean formations include mixing an aqueous phase, an oleaginous phase, and at least one surfactant to produce a mixture, which is sheared to form a drilling fluid, and pumped through a drill string in a drill bit located in a subterranean formation. Rock cuttings are transported from the drill bit to a surface of the subterranean formation and the drilling fluid is circulated in the subterranean formation.

What is claimed is: 
     
         1 . A drilling fluid comprising:
 an aqueous phase;   an oleaginous phase; and   at least one surfactant comprising the formula:
   R—(OC 2 H 4 ) x —OH
 
 where R is a hydrocarbyl group having from 8 to 20 carbon atoms, and 
 x is an integer from 1 and 10. 
   
     
     
         2 . The drilling fluid of  claim 1 , where the surfactant has a hydrophilic-lipophilic balance (HLB) of from 8 to 16. 
     
     
         3 . The drilling fluid of  claim 1 , where the drilling fluid comprises from 28 to 630 pounds per barrel (lb/bbl) of the aqueous phase based on the total weight of the drilling fluid. 
     
     
         4 . The drilling fluid of  claim 1 , where the drilling fluid comprises from 28 to 810 lb/bbl of the oleaginous phase based on the total weight of the drilling fluid. 
     
     
         5 . The drilling fluid of  claim 1 , where the drilling fluid comprises from 0.02 to 180 lb/bbl of the surfactant based on the total weight of the drilling fluid. 
     
     
         6 . The drilling fluid of  claim 1 , where the oleaginous phase comprises one or more components selected from the group consisting of natural oil, synthetic oil, diesel oil, mineral oil, hydrogenanted olefins, unhydrogenated olefins, poly-alpha olefins, linear olefins, branched olefins, polydiorganosiloxanes, silxoanes, organosiloxanes, esters, ethers, acetals, dialkylcarbonates, hydrocarbons, fatty acids, esters of fatty acids, straight chain, branched or cyclical alkyl ethers of fatty acids, and combinations thereof. 
     
     
         7 . The drilling fluid of  claim 1 , where the drilling fluid contains from 0.02 to 180 lb/bbl of one or more additives selected from the group consisting of weighting agents, fluid loss control agents, lost circulation control agents, other surfactants, antifoaming agents, specialty additives, and combinations thereof. 
     
     
         8 . The drilling fluid of  claim 1 , where R is:
 an alkyl group comprising 10 to 16 carbons; or   an alkenyl group comprising from 10 to 16 carbon atoms.   
     
     
         9 . The drilling fluid of  claim 1 , where x is from 5 to 10. 
     
     
         10 . The drilling fluid of  claim 1 , where R comprises 13 carbons. 
     
     
         11 . The drilling fluid of  claim 1 , where the surfactant has an HLB of from 12 to 14. 
     
     
         12 . The drilling fluid of  claim 1 , where the surfactant comprises ethylene oxide condensate of branched isotridecyl alcohol. 
     
     
         13 . The drilling fluid of  claim 1 , where the drilling fluid has a gel strength after 10 seconds of from 1 lb f /100 ft 2  to 50 lb f /100 ft 2 , a gel strength after 10 minutes of from 1 lb f /100 ft 2  to 60 lb f /100 ft 2 , or both. 
     
     
         14 . The drilling fluid of  claim 1 , where the drilling fluid has a plastic viscosity of from 10 cP to 60 cP and a yield point of from 10 lb f /100 ft 2  to 100 lb f /100 ft 2 . 
     
     
         15 . A method of producing a drilling fluid, the method comprising:
 mixing an aqueous phase, an oleaginous phase, and at least one surfactant comprising the formula:
   R—(OC 2 H 4 ) x —OH
 
 where R is a hydrocarbyl group having from 8 to 20 carbon atoms, 
 and x is an integer from 1 and 10, to produce a mixture; and 
   shearing the mixture to form the drilling fluid.   
     
     
         16 . A method of using a drilling fluid to drill a subterranean formation, the method comprising:
 mixing an aqueous phase, an oleaginous phase, and at least one surfactant comprising the formula:
   R—(OC 2 H 4 ) x —OH
 
 where R is a hydrocarbyl group having from 8 to 20 carbon atoms, 
 and x is an integer from 1 and 10, to produce a mixture; 
   shearing the mixture to form the drilling fluid;   pumping the drilling fluid through a drill string in a drill bit located in the subterranean formation;   transporting rock cuttings from the drill bit to a surface of the subterranean formation; and   circulating the drilling fluid in the subterranean formation.   
     
     
         17 . The method of  claim 16 , where the surfactant has an HLB of from 8 to 16. 
     
     
         18 . The method of  claim 16 , where the drilling fluid comprises from 28 to 630 lb/bbl of the aqueous phase, from 28 to 810 lb/bbl of the oleaginous phase, and from 0.02 to 180 lb/bbl of the surfactant, based on the total weight of the drilling fluid. 
     
     
         19 . The method of  claim 16 , where the oleaginous phase comprises one or more components selected from the group consisting of natural oil, synthetic oil, diesel oil, mineral oil, hydrogenanted olefins, unhydrogenated olefins, poly-alpha olefins, linear olefins, branched olefins, polydiorganosiloxanes, silxoanes, organosiloxanes, esters, ethers, acetals, dialkylcarbonates, hydrocarbons, fatty acids, esters of fatty acids, straight chain, branched or cyclical alkyl ethers of fatty acids, and combinations thereof. 
     
     
         20 . The method of  claim 16 , where the drilling fluid contains from 0.02 to 180 lb/bbl of one or more additives selected from the group consisting of weighting agents, fluid loss control agents, lost circulation control agents, other surfactants, antifoaming agents, specialty additives, and combinations of these.