Recovering base oil from contaminated invert emulsion fluid for making new oil- /synthetic-based fluids

Abstract

Base oil can be recovered from contaminated O/SBF by combining a chemical process with a mechanical process. The chemical treatment includes adding a demulsifier, an anionic surfactant, a non-ionic surfactant and/or a mutual solvent to the contaminated O/SBF in an amount effective to separate the base oil from the contaminated O/SBF fluid followed by mechanical separation of oil from water, and optionally from any solids present. The recovered base oil (i.e. conventional drilling fluid, conductive drilling fluid and constant rheology drilling fluid, etc.) may then be reformulated to make a new OBM of the same type from which the base oil was recovered, or as a fuel for engines.

What is claimed is: 
     
         1 . A method of recovering base oil from a contaminated O/SBF comprising solids, and base oil and water in a water and oil emulsion, the method consisting of in this sequence:
 mixing at least microemulsion with the contaminated O/SBF, and where the microemulsion is mixed in an amount effective to break the water and oil emulsion; and   mechanically separating the base oil from the water and solids using a three-phase centrifuge giving recovered base oil; and   combusting the recovered base oil as a fuel source.   
     
     
         2 . The method of  claim 1  further comprising formulating a new O/SBF of the same type that the recovered base oil was separated from. 
     
     
         3 . The method of  claim 1  where the microemulsion concentration ranges from about 0.5 to about 8.0 vol %. 
     
     
         4 . The method of  claim 1  where the base oil in the contaminated O/SBF fluid is selected from the group consisting of diesel, mineral oil, a synthetic base oil, esters, olefins, paraffins, and combinations thereof. 
     
     
         5 . The method of  claim 1  where the microemulsion comprises a surfactant selected from a group of anionic surfactants, non-ionic surfactants, cationic surfactants, and combinations thereof. 
     
     
         6 . The method of  claim 1  where the recovered base oil has an oil/water volume ratio of 95/5 or greater and less than 2 vol % low gravity solids. 
     
     
         7 . The method of  claim 1  where:
 the method has a feed rate of about 13 to about 15 gallons per minute (about 49 to about 57 liters per minute); 
 the method has a recovered base oil rate of from about 10 to about 12 gallons per minute (about 38 to about 45 liters per minute); 
 the recovered base oil has less than 5 vol % low gravity solids; and 
 the mechanically separated solids are solids remaining in the recovered oil phase having an average particle size between about 3 and about 98 microns. 
 
     
     
         8 . A method of recovering base oil from a contaminated O/SBF comprising solids, and base oil and water in a water and oil emulsion, the method consisting of in this sequence:
 mixing at least microemulsion with the contaminated O/SBF, and where the microemulsion is mixed in an amount effective to break the water and oil emulsion, and where the microemulsion comprises a surfactant selected from a group of anionic surfactants, non-ionic surfactants, cationic surfactants, and combinations thereof; and   mechanically separating the base oil from the water and solids using a three-phase centrifuge giving recovered base oil; and   combusting the recovered base oil as a fuel source;   
       where the base oil in the contaminated O/SBF fluid is selected from the group consisting of diesel, mineral oil, a synthetic base oil, esters, olefins, paraffins, and combinations thereof. 
     
     
         9 . The method of  claim 8  further comprising formulating a new O/SBF of the same type that the recovered base oil was separated from. 
     
     
         10 . The method of  claim 8  where the microemulsion concentration ranges from about 0.5 to about 8.0 vol %. 
     
     
         11 . The method of  claim 8  where the recovered base oil has an oil/water volume ratio of 95/5 or greater and less than 2 vol % low gravity solids. 
     
     
         12 . The method of  claim 8  where:
 the method has a feed rate of about 13 to about 15 gallons per minute (about 49 to about 57 liters per minute); 
 the method has a recovered base oil rate of from about 10 to about 12 gallons per minute (about 38 to about 45 liters per minute); 
 the recovered base oil has less than 5 vol % low gravity solids; and 
 the mechanically separated solids are solids remaining in the recovered oil phase having an average particle size between about 3 and about 98 microns. 
 
     
     
         13 . A method of recovering base oil from a contaminated O/SBF comprising solids, and base oil and water in a water and oil emulsion, the method consisting of in this sequence:
 mixing at least microemulsion with the contaminated O/SBF where the microemulsion concentration ranges from about 0.5 to about 8.0 vol %; and   mechanically separating the base oil from the water and solids using a three-phase centrifuge giving recovered base oil having an oil/water volume ratio of 95/5 or greater and less than 2 vol % low gravity solids; and   combusting the recovered base oil as a fuel source.   
     
     
         14 . The method of  claim 13  further comprising formulating a new O/SBF of the same type that the recovered base oil was separated from. 
     
     
         15 . The method of  claim 13  where the base oil in the contaminated O/SBF fluid is selected from the group consisting of diesel, mineral oil, a synthetic base oil, esters, olefins, paraffins, and combinations thereof. 
     
     
         16 . The method of  claim 13  where the microemulsion comprises a surfactant selected from a group of anionic surfactants, non-ionic surfactants, cationic surfactants, and combinations thereof. 
     
     
         17 . The method of  claim 13  where:
 the method has a feed rate of about 13 to about 15 gallons per minute (about 49 to about 57 liters per minute); 
 the method has a recovered base oil rate of from about 10 to about 12 gallons per minute (about 38 to about 45 liters per minute); 
 the recovered base oil has less than 5 vol % low gravity solids; and 
 the mechanically separated solids are solids remaining in the recovered oil phase having an average particle size between about 3 and about 98 microns.