Colloidal silica addition to promote the separation of oil from water

Abstract

The combination of colloidal silica in conjunction with a chemical, such as a cationically-modified water soluble polymer, e.g. aluminum brine dispersion polymer, clarifies combinations of oil and water, for instance wastewater comprising an oil-in-water emulsion. The colloidal silica may have an average silica particle size of about 0.5 to about 10 nanometers.

What is claimed is: 
     
         1 . A fluid composition comprising:
 a combination of oil and water;   colloidal silica, where particle size of silica in the colloidal silica ranges from about 0.5 to about 10 nanometers; and   a chemical selected from the group consisting of at least one anionic chemical that is a dithiocarbamate (DTC) and at least one cationic chemical that is an aluminum brine dispersion polymer;   
       where the amounts of colloidal silica and chemical are effective to at least partially separate the oil from the water in the combination of oil and water. 
     
     
         2 . The fluid composition of  claim 1  where the chemical comprises at least one anionic chemical that is a dithiocarbamate (DTC) and at least one cationic chemical that is an aluminum brine dispersion polymer 
     
     
         3 . The fluid composition of  claim 1  where the fluid composition is present in an apparatus selected from the group consisting of a free water knockout, a dissolved air flotation unit, a dissolved air flotation unit, a skim tank, a water clarifier, a sludge dewatering belt press, and combinations thereof. 
     
     
         4 . The fluid composition of  claim 1  where:
 the amount of colloidal silica in the fluid composition ranges from about 0.5 ppm to about 200 ppm; and 
 the amount of the chemical in the fluid composition ranges from about 1 ppm to about 1000 ppm. 
 
     
     
         5 . The fluid composition of  claim 1  where the fluid composition is selected from the group consisting of an oil-in-water emulsion, a bicontinuous emulsion, and combinations thereof. 
     
     
         6 . A fluid composition comprising:
 a combination of oil and water, where the oil is produced from an oil field or where the combination of oil and water is a combination produced from an oilfield;   colloidal silica, where the amount of colloidal silica in the oil and water combination ranges from about 0.5 ppm to about 200 ppm, and where particle size of silica in the colloidal silica ranges from about 0.5 to about 10 nanometers; and   a chemical selected from the group consisting of aluminum brine dispersion polymers, alone or in combination with a dithiocarbamate (DTC), where the amount of the chemical in the oil and water combination ranges from about 1 ppm to about 1000 ppm.   
     
     
         7 . The fluid composition of  claim 6  where the fluid composition is present in an apparatus selected from the group consisting of a free water knockout, a dissolved air flotation unit, a dissolved air flotation unit, a skim tank, a water clarifier, a sludge dewatering belt press, and combinations thereof. 
     
     
         8 . The fluid composition of  claim 6  where the fluid composition is selected from the group consisting of an oil-in-water emulsion, a bicontinuous emulsion, and combinations thereof. 
     
     
         9 . A treating composition for at least partially separating a combination of oil and water, the treating composition comprising:
 colloidal silica, where particle size of silica in the colloidal silica ranges from about 0.5 to about 10 nanometers; and   a chemical selected from the group consisting of at least one anionic chemical that is a dithiocarbamate (DTC) and at least one cationic chemical that is an aluminum brine dispersion polymer.   
     
     
         10 . The treating composition of  claim 9  where the chemical comprises at least one anionic chemical that is a dithiocarbamate (DTC) and at least one cationic chemical that is an aluminum brine dispersion polymer 
     
     
         11 . The treating composition of  claim 9  where the amount of colloidal silica and the amount of the chemical are approximately the same.