Destabilization of crude oil emulsions by combining chemicals and electric fields

Abstract

In today s oil industry the increasing scarcity of the conventional oil is inevitable and pushes the oil companies towards the exploitation of unconventional oils such as oil- sands, heavy oil and extra heavy oil. During the recovery process of crude oil from the reservoir emulsified water forms continuously. These emulsions are highly undesirable from a process and product quality point of view and need to be treated to remove the water. In order to meet these challenges, the understanding of the colloidal properties is crucial. One of the most commonly used methods in treating water-in-oil emulsions is demulsification which employs surfactants to enhance the emulsion breaking process. Furthermore, other emulsion breaking methods can be combined in order to further in- crease the effectiveness of the water-in-oil separation, such as utilization of electric fields.

The present study investigates the interplay between chemicals and electric fields on the stability of emulsions with and without presence of flocculated asphaltenes. At Ugelstad laboratory the electric field was provided by the electric field cell and is a simple method that can be used to study emulsion stability with electric field and chemicals. The chem- icals used involved demulsifiers from the Igepal series and the asphaltene precipitation inhibitors DBSA, Nonylphenol and two products from AkzoNobel (OFD-15-001 and OFD- 15-002). DBSA was the most prominent among the chemicals tested to induce significant separation of the emulsions with presence of flocculated asphaltenes in combination with the electric field cell, and thereby taken into further examination at Wärtsiä. The Igepal surfactants, Nonylphenol and products from AkzoNobel did not enhance the separation performance of the emulsions in combination with the electric field cell.

The static batch test at Wärtsilä provided the electric field and is a specially constructed instrument developed by Wärtsilä s own employees. The results from Wärtsilä suggest that the DBSA yield a significant improvement of the separation of the emulsions with presence of flocculated asphaltenes, which are consistent with the results from Ugelstad laboratory. Therefore, the electric field cell seems promising to predicting good separation performance of stable emulsions at Wärtsilä and may be used to select suitable chemicals prior the experiments with the static batch test. This can be more efficient and cost sav- ing considering a greater quantity of experiments can be conducted and less supplies are consumed. However, it is necessary to conduct additional experiments to confirm the similarity of the electric field cell and static batch test.