Applied Statistics: Crude Oil Emulsions and Demulsifiers

Abstract

Water‐in‐crude oil emulsions are encountered at many oilfield production facilities. These emulsions are often inherently stable requiring the use of chemical treatment, heat, and residence time to effect resolution. The addition of chemical demulsifiers in small levels can greatly facilitate oil–water separation. Even with numerous demulsifier applications in place throughout the world, there still remains a great deal to understand regarding how to streamline demulsifier selection, how demulsifiers counter the indigenous crude oil components and properties that impart emulsion stability and which crude oil components and process variables are most critical in describing emulsion strength. Field studies were undertaken to address these concerns using two statistical methods—experimental design and cluster analysis. Experimental design was used to investigate the importance of four process variables, while cluster analysis used an ensemble of demulsifiers and crude oil characterization to build models describing emulsion stability.

Keywords:

• Crude oil emulsions
• Demulsifiers
• Emulsion stability
• Oil–water separation
• SARA
• Statistical analysis

Acknowledgments

We are grateful to Nalco Energy Services for permission to publish this work. We also thank Bob Marble for assistance in conducting the field bottle testing, Samuel Marsh for performing the crude oil fractionations, and Becky Ramsey and Bob Pultz for determination of naphthenic acid and solid content.