Rag Layer Formation and Stability of Crude Oil Emulsion Under Different Imposed Mechanical Energy and Temperatures

Crude oil emulsion is a significant contributor of production losses in the Oil and Gas industry. The stability of the emulsion determines the magnitude of losses to be coped with by the industry. Several factors contribute to the stability of an emulsion hence this research was carried out to study the stability of crude oil emulsion and rag layer (unresolved emulsion) formation under four different imposed mechanical energy (by varying homogenizer speed) and two mixing temperatures using two types of crude oils. Five tests were conducted on each emulsion to study on the properties of the emulsions for a more comprehensive analysis. The five tests are bottle test (emulsion stability testing), Micro-Differential Scanning Calorimetry (Micro-DSC), Cross-Polarized Microscopy (CPM), rheological test (Rheometer) and titration test (water content determination). Crude Oil A produces water-in-oil emulsion while Crude Oil B produces oil-in-water emulsion. High mixing temperatures produce loose emulsions that do not have rag layer issues while the lower (mixing) temperature emulsions are tighter and forms rag layer. The imposed mechanical energy has a direct effect on the emulsion stability. The highest mixing speed produces the most stable emulsion while the lowest speed produces the least stable emulsion. The middle range mixing speeds on the other hand shows an inconsistency in its stability pattern. All the oil layers after separation meet the requirement set by the industry except for the highest mixing energy emulsion at 60°C. The regulations by the Environmental Quality Act 1974 for discharge water are also met by all water layers except for emulsion that was mixed with the highest mixing speed.