Blends of esters with isomerized olefins and other hydrocarbons as base oils for invert emulsion oil muds

Abstract

Environmentally acceptable or regulatory compliant oil-based drilling fluids and methods of using same in drilling a wellbore in a subterranean formation are disclosed. The fluids are able to meet environmental regulations while maintaining acceptable oil mud rheology and overall oil mud performance. The fluids are comprised of an invert emulsion. The base or continuous phase of the emulsion is comprised of esters blended with isomerized olefins, and/or other hydrocarbons, such as paraffins, mineral oils or glyceride triesters or combinations thereof. Alternatively, the emulsion has as a base comprising isomerized olefins blended with other hydrocarbons such as linear alpha olefins, paraffins or naphthenes.

We claim:  
     
         1 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising a blend of esters and isomerized olefins.  
     
     
         2 . The drilling fluid of  claim 1  wherein said isomerized olefins have a straight chain structure.  
     
     
         3 . The drilling fluid of  claim 1  wherein said isomerized olefins have a branched structure.  
     
     
         4 . The drilling fluid of  claim 1  wherein said isomerized olefins have a cyclic structure.  
     
     
         5 . The drilling fluid of  claim 1  wherein said isomerized olefins have about 10 to about 30 carbon atoms.  
     
     
         6 . The drilling fluid of  claim 1  wherein said isomerized olefins comprise about 1 to about 99 weight percent of said blend.  
     
     
         7 . The drilling fluid of  claim 1  wherein said esters comprise about 5 to about 99 weight percent of said blend.  
     
     
         8 . The drilling fluid of  claim 1  wherein said esters are prepared from fatty acids and alcohols.  
     
     
         9 . The drilling fluid of  claim 1  wherein said esters are prepared from fatty acids having about 6 to about 14 carbon atoms and an alcohol.  
     
     
         10 . The drilling fluid of  claim 1  wherein said esters are prepared from fatty acids having about 12 to about 14 carbon atoms and 2-ethyl hexanol.  
     
     
         11 . The drilling fluid of  claim 1  wherein said esters are prepared from fatty acids having about 8 carbon atoms and 2-ethyl hexanol.  
     
     
         12 . The drilling fluid of  claim 1  wherein said esters are prepared from olefins.  
     
     
         13 . The drilling fluid of  claim 1  wherein said esters are prepared from olefins and fatty acids or alcohols.  
     
     
         14 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising a blend of esters and olefin hydrocarbons.  
     
     
         15 . The drilling fluid of  claim 14  wherein said olefin hydrocarbons are selected from the group comprising branched olefins, poly-branched olefins, and mixtures thereof.  
     
     
         16 . The drilling fluid of  claim 15  wherein at least one double bond site is either internal the molecule or at the alpha position of the molecule.  
     
     
         17 . The drilling fluid of  claim 14  wherein said olefin hydrocarbons comprise linear olefins where the double bond site or sites are internal the molecule.  
     
     
         18 . The drilling fluid of  claim 14  wherein said olefin hydrocarbons comprise about 10 to about 30 carbon atoms.  
     
     
         19 . The drilling fluid of  claim 14  wherein said olefin hydrocarbons comprise about about 1 to about 99 weight percent of said blend.  
     
     
         20 . The drilling fluid of  claim 14  wherein said esters comprise about 10 to about 99 weight percent of said blend.  
     
     
         21 . The drilling fluid of  claim 14  wherein said esters are prepared from fatty acids and alcohols.  
     
     
         22 . The drilling fluid of  claim 14  wherein said esters are prepared from fatty acids having about 6 to about 14 carbon atoms and an alcohol.  
     
     
         23 . The drilling fluid of  claim 14  wherein said esters are prepared from fatty acids having about 12 to about 14 carbon atoms and 2-ethyl hexanol.  
     
     
         24 . The drilling fluid of  claim 14  wherein said esters are prepared from fatty acids having about 8 carbon atoms and 2-ethyl hexanol.  
     
     
         25 . The drilling fluid of  claim 14  wherein said esters are prepared from olefins.  
     
     
         26 . The drilling fluid of  claim 14  wherein said esters are prepared from olefins and fatty acids or alcohols.  
     
     
         27 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising a blend of esters and paraffin hydrocarbons.  
     
     
         28 . The drilling fluid of  claim 27  wherein said paraffin hydrocarbons are selected from the group comprising linear paraffins, branched paraffins, poly-branched paraffins, cyclic paraffins, isoparaffins, and mixtures thereof.  
     
     
         29 . The drilling fluid of  claim 27  wherein said paraffin hydrocarbons have about 10 to about 30 carbon atoms.  
     
     
         30 . The drilling fluid of  claim 27  wherein said paraffin hydrocarbons comprise about 1 to about 99 weight percent of said blend.  
     
     
         31 . The drilling fluid of  claim 27  wherein said esters comprise about 10 to about 99 weight percent of said blend.  
     
     
         32 . The drilling fluid of  claim 27  wherein said esters are prepared from fatty acids and alcohols.  
     
     
         33 . The drilling fluid of  claim 27  wherein said esters are prepared from fatty acids having about 6 to about 14 carbon atoms and an alcohol.  
     
     
         34 . The drilling fluid of  claim 27  wherein said esters are prepared from fatty acids having about 12 to about 14 carbon atoms and 2-ethyl hexanol.  
     
     
         35 . The drilling fluid of  claim 27  wherein said esters are prepared from fatty acids having about 8 carbon atoms and 2-ethyl hexanol.  
     
     
         36 . The drilling fluid of  claim 27  wherein said esters are prepared from olefins.  
     
     
         37 . The drilling fluid of  claim 27  wherein said esters are prepared from olefins and fatty acids or alcohols.  
     
     
         38 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising a blend of esters and mineral oil hydrocarbons.  
     
     
         39 . The drilling fluid of  claim 38  wherein said mineral oil hydrocarbons comprise less than about 1 weight percent aromatics.  
     
     
         40 . The drilling fluid of  claim 38  wherein said mineral oil hydrocarbons are selected from the group comprising linear paraffins, isoparaffins, cycloparaffins, branched paraffins, cyclic paraffins, and mixtures thereof, having about 10 to about 30 carbon atoms.  
     
     
         41 . The drilling fluid of  claim 38  wherein said mineral oil hydrocarbons comprise olefins, having about 10 to about 30 carbon atoms.  
     
     
         42 . The drilling fluid of  claim 41  wherein said olefins have chemical structures similar to paraffins, isoparaffins, cycloparaffins, or branched paraffins.  
     
     
         43 . The drilling fluid of  claim 38  wherein said esters comprise at least about 10 to about 99 weight percent of said blend.  
     
     
         44 . The drilling fluid of  claim 38  wherein said esters are prepared from fatty acids and alcohols.  
     
     
         45 . The drilling fluid of  claim 38  wherein said esters are prepared from fatty acids having about 6 to about 14 carbon atoms and 2-ethyl hexanol.  
     
     
         46 . The drilling fluid of  claim 44  wherein said esters are prepared from fatty acids having about 12 to about 14 carbon atoms and 2-ethyl hexanol.  
     
     
         47 . The drilling fluid of  claim 44  wherein said esters are prepared from fatty acids having about 8 carbon atoms and 2-ethyl hexanol.  
     
     
         48 . The drilling fluid of  claim 38  wherein said esters are prepared from olefins.  
     
     
         49 . The drilling fluid of  claim 38  wherein said esters are prepared from olefins and fatty acids or alcohols.  
     
     
         50 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising a blend of esters and glyceride triesters.  
     
     
         51 . The drilling fluid of  claim 50  wherein said glyceride triesters comprise about 1 to about 99 weight percent of said blend.  
     
     
         52 . The drilling fluid of  claim 50  wherein said glyceride triesters are obtained or derived from an oil selected from the group comprising: rapeseed oil, olive oil, canola oil, castor oil, coconut oil, corn oil, cottonseed oil, lard oil, linseed oil, neatsfoot oil, palm oil, peanut oil, perilla oil, rice bran oil, safflower oil, sardine oil, sesame oil, soybean oil, sunflower oil, and mixtures thereof.  
     
     
         53 . The drilling fluid of  claim 50  wherein said esters comprise about 10 to about 99 weight percent of said blend.  
     
     
         54 . The drilling fluid of  claim 50  wherein said esters are prepared from fatty acids and alcohols.  
     
     
         55 . The drilling fluid of  claim 54  wherein said esters are prepared from fatty acids having about 12 to about 14 carbon atoms and 2-ethyl hexanol.  
     
     
         56 . The drilling fluid of  claim 54  wherein said esters are prepared from fatty acids and alcohols having about 8 carbon atoms and 2-ethyl hexanol.  
     
     
         57 . The drilling fluid of  claim 50  wherein said esters are prepared from olefins.  
     
     
         58 . The drilling fluid of  claim 50  wherein said esters are prepared from olefins and fatty acids or alcohols.  
     
     
         59 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising a blend of linear alpha olefins and paraffin hydrocarbons.  
     
     
         60 . The drilling fluid of  claim 59  wherein said paraffin hydrocarbons are selected from the group comprising linear paraffins, branched paraffins, poly-branched paraffins, cyclic paraffins, isoparaffins, and mixtures thereof.  
     
     
         61 . The drilling fluid of  claim 59  wherein said paraffin hydrocarbons have about 10 to about 30 carbon atoms.  
     
     
         62 . The drilling fluid of  claim 59  wherein said paraffin hydrocarbons comprise about 1 to about 99 weight percent of said blend.  
     
     
         63 . The drilling fluid of  claim 59  wherein said paraffin hydrocarbons comprise less than about 50 weight percent of the blend.  
     
     
         64 . The drilling fluid of  claim 59  wherein said linear alpha olefins comprise about 1 to about 99 weight percent of said drilling fluid.  
     
     
         65 . The drilling fluid of  claim 59  wherein said linear alpha olefins comprise about 10 to about 30 carbon atoms.  
     
     
         66 . A drilling fluid comprising an invert emulsion where said invert emulsion has a base or continuous phase comprising isomerized olefins and paraffin hydrocarbons.  
     
     
         67 . The drilling fluid of  claim 66  wherein said paraffin hydrocarbons are selected from the group comprising linear paraffins, branched paraffins, poly-branched paraffins, cyclic paraffins, isoparaffins, or mixtures thereof.  
     
     
         68 . The drilling fluid of  claim 66  wherein said paraffin hydrocarbons have about 10 to about 30 carbon atoms.  
     
     
         69 . The drilling fluid of  claim 66  wherein said paraffin hydrocarbons comprise about 1 to about 99 weight percent of said blend.  
     
     
         70 . The drilling fluid of  claim 66  wherein said isomerized olefins comprise about 1 to about 99 weight percent of said drilling fluid.  
     
     
         71 . The drilling fluid of  claim 66  wherein said isomerized olefins have about 10 to about 30 carbon atoms.  
     
     
         72 . The drilling fluid of  claim 56  wherein said isomerized olefins are selected from the group comprising internal olefins, cyclic olefins, and mixtures thereof.  
     
     
         73 . The drilling fluid of  claim 72  wherein said internal olefins may be straight chain or branched chain.  
     
     
         74 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising a blend of naphthenic hydrocarbons and other paraffin hydrocarbons.  
     
     
         75 . The drilling fluid of  claim 74  wherein said paraffin hydrocarbons are selected from the group comprising linear paraffins, branched paraffins, poly-branched paraffins, isoparaffins, or mixtures thereof.  
     
     
         76 . The drilling fluid of  claim 74  wherein said paraffin hydrocarbons have about 10 to about 30 carbon atoms.  
     
     
         77 . The drilling fluid of  claim 74  wherein said paraffin hydrocarbons comprise about 1 to about 99 weight percent of said blend.  
     
     
         78 . The drilling fluid of  claim 74  wherein said napthenic hydrocarbons comprise about 1 to about 99 weight percent of said drilling fluid.  
     
     
         79 . The drilling fluid of  claim 74  wherein said napthenic hydrocarbons comprise a saturated, cycloparaffinic material having a chemical formula:  
       C n H 2n    
       where n is about 5 to about 30.  
     
     
         80 . A drilling fluid comprising an invert emulsion wherein said invert emulsion has a base or continuous phase comprising isomerized olefins and other hydrocarbons.  
     
     
         81 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 1  and circulating same in said wellbore during said drilling.  
     
     
         82 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 14  and circulating same in said wellbore during said drilling.  
     
     
         83 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 27  and circulating same in said wellbore during said drilling.  
     
     
         84 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 38  and circulating same in said wellbore during said drilling.  
     
     
         85 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 50  and circulating same in said wellbore during said drilling.  
     
     
         86 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 59  and circulating same in said wellbore during said drilling.  
     
     
         87 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 66  and circulating same in said wellbore during said drilling.  
     
     
         88 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 74  and circulating same in said wellbore during said drilling.  
     
     
         89 . A method of drilling a wellbore in a subterranean formation, said method comprising obtaining or preparing the drilling fluid of  claim 80  and circulating same in said wellbore during said drilling.