(252f) A Rapid Microwave-Assisted Bottle Test Method to Determine the Crude Emulsion Stability

The main objective of this study is to use microwaves to develop a fast, energy efficient, and economical method to quantify the stability of crude oil and water emulsions. The crude oil emulsions are formed by high shear mixing of process water and crude oil during pumping, desalting and transportation through wellbores and pipelines and are stabilized by emulsifying agents that form interfacial films at the oil-water interface. Separation of these crude oil emulsions is expensive and requires significant amounts of energy and chemical demulsifiers. Due to the substantial cost of chemical demulsifiers used during the crude processing, there is a commercial interest in developing an inexpensive method to optimize their use. Currently, the widely used industry standard for this measurement, the Bottle Test, can be time consuming and has limitations when dealing with extremely heavy crude emulsions that sediment over long timescales because of low density differences and also with tight emulsions that flocculate and coalesce over long timescales because of high interfacial area to volume ratios. Also, the said Bottle Test is performed off the oil fields, usually in a third-party laboratory. Thus, increasing time and cost to perform the optimization process. In this study, we have created a rapid and simple microwave demulsification test that would be used in correlation to the standard Bottle Test.

The tight crude oil emulsions, characterized by suspended droplets on the order of submicron to tens of microns, often cause serious problems to the wellbores and pipelines such as clogging, corrosion, and pump failures. Our previously developed microwave demulsification process proved to be orders of magnitude faster at separating heavy crudes and tight emulsions when compared to heat and gravity settling alone, as used by the traditional Bottle Test.

To simulate field conditions, we mixed two crude oils to prepare samples with American Petroleum Institute (API) gravities between 28.9° and 46.0°. These crudes were mixed with water to create emulsions containing between 20% and 80% water. This array of Water-in-Oil (W/O) and Oil-in-Water (O/W) emulsions with different densities and viscosities were mixed at varying shear rates. A Polyol Block copolymer, and Polyethylene Glycol 2000 (Mol. Wt. 2000) were used as demulsifying agents at different concentrations. The crude oil emulsions mixed with the demulsifying agents were subjected to both the traditional Bottle Test as well as the rapid microwave test. The amount of phase separation was visually recorded and the residual water content in the separated oil phase was measured using the Karl Fisher titration. Using the separation data for both methods, we developed a correlation between the two methods. The results from the rapid microwave test can now be used to determine how they correlate with the standard bottle test.