An environmental-scanning-electron microscope investigation into the effect of biofilm on the wettability of quartz

The wettability relationships between oil, brine, gas, and rock are important in understanding reservoir dynamics. Chemical surfactants, scale inhibitors, and microbes introduced during exploration and production are all known to affect reservoir wettabilty. However, little thought has been given to the possibility of microbial contamination of cores during core preservation, handling, storage, or analysis and the effect that this may have on measuring parameters such as wettability. In an attempt to understand how wettability analysis of sandstone cores may be altered by the presence of microbial contamination, this paper examines the effect on wettability of bacterial/fungal biofilms on quartz. Wettability data for quartz and quartz colonized by bacterial/fungal biofilms were collected using an environmental scanning electron microscope (ESEM). The results illustrate that the introduction of bacteria and fungi to such systems can change wettability from hydrophilic to hydrophobic. These findings have important implications within the oil industry. Copyright © 2010 Society of Petroleum Engineers.