Methods for removing particulate solids and water from petroleum crudes

The method for removing inorganic particulate solids and water from a heavy crude oil obtained by an enhanced recovery procedure and which has a BS&W content in excess of pipeline specifications including a significant proportion of water present as the disperse phase of a water-in-oil emulsion, the heavy crude oil having been blended with a compatible hydrocarbon diluent to provide an API gravity of at least 17, comprising treating the blended crude to destabilize the water-in-oil emulsion wherein said treating step is accomplished by adjusting the pH of the crude to at least 8, and

• uniformly distributing throughout the crude a small proportion of at least one additive selected from the group consisting of alkali metal, alkaline earth metal and ammonium hydrosulfites, hydrosulfides and monosulfides,
• the amount of the at least one additive being in the range of from a few hundreths of a percent to several percent of the weight of the blended crude;
• providing in uniform distribution throughout the crude so treated with a demulsifier composition comprising
• an anionic surfactant which is soluble in oil,
• a nonionic surfactant which is insoluble in water and dispersible in oil, and
• a cationic surfactant which is soluble in water,
• the anionic surfactant constituting 5-20 parts by weight and the nonionic and cationic surfactants each constituting 2-10 parts by weight of the demulsifier composition,
• the amount of the demulsifier composition distributed throughout the crude being such that the total surfactant weight equals 50-300 grams per barrel of blended crude;
• separating the resulting crude into at least an oil phase and a water phase;
• and
• recovering the oil phase as clean blended crude having a BS&W content within pipeline specifications.