Emulsification characteristics and dehydration of shale oil emulsions under high-frequency electric field

Abstract

In the face of depleting conventional oil and natural gas reserves, the exploitation of shale oil resources increasingly important. However, the high stability of shale oil emulsions presents a significant challenge to its extraction. In this paper, the differences between shale oil and conventional crude oil and the reasons for the stability of shale oil emulsions were explored. In addition, different dehydration technologies for shale oil emulsions were compared and optimum operating parameters were determined through laboratory-scale experiments. The results show that shale oil emulsions contain much smaller droplets (< 2.25 μm) compared with conventional crude oil emulsions. Further, the high wax content of shale oil allows it to form a high-strength interfacial film at the oil-water interface under the combined action of fracturing fluids and natural emulsifiers, making the emulsion highly stable. Demulsification experiments showed that the use of high-frequency alternating current (AC) pulsed electric fields is an effective method for breaking shale oil emulsions. The optimal demulsification parameters were found to be an electric field frequency of 4 kHz, a field strength of 150 kV·m-1, a residence time of 50 min, an operating temperature of 55 °C, and a demulsifier concentration of 100 ppm. Under these conditions, the dehydrated shale oil was able to meet the standards for commercial crude oil.