Heavy crude oil from the Mukhaizna oil field in Oman was emulsified with water in an attempt to decrease its viscosity. The oil has a kinematic viscosity of 7160 mm 2 /s at 30 °C, density of 0.9571 g/cm 3 at 15 °C, and asphaltene content of 4.7 wt %. The effects of changes in water content (20-30 wt %), type and concentration of surfactant, addition of a water-soluble polymer, and agitation temperatures (25 and 42 °C) were studied in order to identify the optimum viscosity and stability for transporting the oil. The stability was measured by the water separation rate from the emulsion. For the Mukhaizna heavy crude oil, 21-22 wt % of water content and 0.4 wt % of nonylphenol ether type or higher alcohol alkylene oxide type surfactant were found to be optimum for a stable emulsion with a concomitant significant decrease in viscosity to about 1 / 3 -1 / 4 that of the original crude oil. This improves the transportability of the heavy crude oil and makes it suitable for use as a power generation fuel.
Summary
As an oil field matures, it produces larger quantities of produced water. Appropriate treatment levels and technologies depend on a number of factors, such as disposal methods or usage aims, environmental impacts, and economics. In this study, a pilot plant with a capacity of 50 m3/day was used to conduct flotation, filtration, and adsorption trials for produced-water treatment at a crude-oil gathering facility. The flexible design of the plant allows for the testing of different combinations of these processes on the basis of the requirements of the water to be treated. The subject water during this study was a complex and changing mixture of brine and oil from different oil fields. Induced-gas-flotation (IGF) trials were conducted, with different coagulant [poly-aluminum chloride (PAC)] -addition rates from 0 to 820 mg•L-1. Inlet-dispersed oil-in-water (OIW) concentrations were quite varied during the trials, ranging from 39 to 279 mg•L-1 (fluorescence-analysis method). Turbidity also varied, ranging from 85 to 279 FTU. Through coagulation/flocculation and flotation, dispersed oils were removed from the water. PAC addition ranging from 60 to 185 mg•L-1 resulted in the reduction of the dispersed-oil concentration to less than 50 mg•L-1 in treated water; and PAC addition ranging from 101 to 200 mg•L-1 resulted in the reduction of the dispersed-oil concentration to less than 15 mg•L-1 in treated water. Turbidity was also reduced through flotation, with trial average reductions ranging from 57 to 78%. Filtration further reduced turbidity at rates greater than 80% through the removal of any suspended solids remaining from flotation. Activated-carbon adsorption reduced OIW concentrations of flotation-/filtration-treated water to 5 mg•L-1 (infrared-analysis method) through the removal of dissolved oil remaining in the water. Results confirmed that such adsorption treatment would be more practical for water with lower chemical-oxygen-demand (COD) concentration because high-COD concentrations in water reduce the lifetime of activated carbon dramatically.
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