Wettability is a fundamental control on hydrocarbon mobility with ‘oil-wet’ conditions favoring the adhesion of hydrophobic liquids to mineral surfaces while ‘water-wet’ systems favor adhesion of water to mineral surfaces. In systems that are strongly oil-wet, hydrocarbon movement is inhibited by adhesion to mineral surfaces; while in systems that are strongly water-wet, the hydrocarbon mobility requires overcoming capillary forces that manifest as the entry pressure at pore throats, leading to snap-off. These macroscopic effects are significant factors on primary and secondary recovery and should inform completion fluid design.
Traditional wettability models do not distinguish between oil directly bound to mineral surfaces and oil that adheres to the mineral surfaces by electrostatic interaction through a water film. This distinction is important since laboratory and field cases suggest that a large portion of hydrocarbons are loosely bound to mineral surfaces by electrostatic interaction through thin water films. This portion of oil adhesion is a function of salinity, temperature, surface properties and hydrocarbon polarity. In contrast, directly bound hydrocarbons are not mobile without solvent application.
The new conceptual models offer explanations for experimental and field observations of the relationship between wettability and salinity. The interactions in these multiphase systems can be described with standard absorption and adsorption reactions. This approach combines modified geochemical codes informed with experimental data. Comparison of data with predictions from these models offer insight into how changes in water chemistry and pH including CO2 injection will alter wettability
About the Speaker
Dr. Thyne graduated from Texas A&M University in 1979 and began his career in the earth sciences as a Research Geochemist at the Arco Oil and Gas research facility in Plano, Texas. He received his Ph.D. in Geology from the University of Wyoming in 1991 and taught at California State University-Bakersfield and the Colorado School of Mines until 2005. He returned to the University of Wyoming in 2006 at the Enhanced Oil Recovery Institute. Over his time at EORI he became immersed in the possibilities of changing water chemistry to improve oil recovery studying the process in both the laboratory and field. In 2012 he left EORI and formed ESal LLC. Today Geoffrey is the Chief Technology Officer at ESal and with over 35 years in oil and gas, he is an expert in increasing recovery by manipulation of water chemistry to alter wettability in petroleum reservoirs. His prime motivation is to overcome the limitations of current recovery practices.