Maintenance of oil production and refining equipment

Abstract

The deposition of asphaltenes and/or petroleum waxes can be inhibited and/or asphaltenes and/or petroleum waxes can be removed from a well, pipe or vessel by contacting the asphaltene and/or petroleum wax or the well pipe or vessel adjacent a location where deposition of asphaltene and/or petroleum wax is expected, with a solvent including at least one compound of the formula (I): R 1 —(AO) n —OOC—(CH 2 ) m —Ph—(R 2 ) p where R 1 is a C 1 to C 20 hydrocarbyl group; AO is an alkyleneoxy group and may vary along the (poly)alkyleneoxy chain; n is 1 or from 1 to 100; m is 0, 1 or 2; and Ph is a phenyl group, which may be substituted with groups (R 2 ) p where each R 2 is independently a C 1 to C 4 alkyl or alkoxy group; and p is 0, 1 or 2, and subsequently removing the solvent with softened, dissolved or dipersed asphaltenes and/or petroleum waxes from the well, pipe or vessel.

1  A method of removing from, or preventing or inhibiting the deposition in, a well, pipe or vessel, of asphaltenes and/or petroleum waxes which comprises contacting the asphaltene and/or petroleum wax or the well pipe or vessel adjacent a location where deposition of asphaltene and/or petroleum wax is expected, with a solvent including at least one compound of the formula (I): 
       R 1 —(AO) n —OOC—(CH 2 ) m —Ph—(R 2 ) p   (I) 
       where 
 R 1  is a C 1  to C 20  hydrocarbyl group;  
 AO is an alkyleneoxy group and may vary along the (poly)alkyleneoxy chain;  
 n 0 or from 1 to 100;  
 m is 0, 1 or 2; and  
 Ph is a phenyl group, which may be substituted with groups (R 2 ) p ; where 
 each R 2  is independently a C 1  to C 4  alkyl or alkoxy group; and p is 0, 1 or 2; and subsequently removing the solvent with softened, dissolved or dispersed asphaltenes and/or petroleum waxes from the well, pipe or vessel:  
 
 
     
     
         2  A method as claimed in  claim 1  wherein m, n and p are all 0.  
     
     
         3  A method as claimed in either  claim 1  or  claim 2  wherein R 1  is a C 3  to C 5  branched alkyl group.  
     
     
         4  A method as claimed in any one of  claims 1  to  3  wherein the solvent is or includes iso-propyl benzoate.  
     
     
         5  A method as claimed in either  claim 1  or  claim 2  wherein R 1  is a C8 to C20 branched and/or unsaturated alkyl or alkenyl group.  
     
     
         6  A method as claimed in any one of  claims 1  to  5  wherein the asphaltene and/or petroleum wax is contacted with the solvent at a superambient temperature.  
     
     
         7  A method as claimed in any one of  claims 1  to  6  wherein the solvent includes a dispersant for the asphaltene and/or petroleum wax.  
     
     
         8  A method as claimed in any one of  claims 1  to  7  to treat an oil storage tank, vessel, or oil refinery pipework to remove deposits of asphaltenes and/or petroleum waxes, in which a solvent including a compound of the formula (I) as defined above, is introduced into the tank, vessel or pipework at or adjacent the location of a deposit of asphaltene and/or petroleum wax, and subsequently softened dispersed or dissolved asphaltene and/or petroleum wax is removed from the tank, vessel or pipework.  
     
     
         9  A method as claimed in any one of  claims 1  to  7  to treat an oil well to treat an oil well to remove a deposit of asphaltenes and/or petroleum waxes, in which a solvent including a compound of the formula (I) as defined above, is introduced into the oil well in or adjacent to a deposit on a surface or in a rock formation and subsequently softened dispersed or dissolved asphaltene and/or petroleum wax is removed from the surface or formation.  
     
     
         10  A method as claimed in any one of  claims 1  to  7  to treat an oil well to inhibit or prevent the deposition of asphaltenes and/or petroleum waxes, in which a stream of a solvent including a compound of the formula (I) as defined above, is introduced into the oil well in a location, particularly onto a surface or into a rock formation, where deposition is expected thereby carrying away asphaltenes and/or petroleum waxes before they are deposited on the surface or in the formation.