Date Thesis Awarded
Honors Thesis -- Open Access
Bachelors of Science (BS)
In many reservoirs, oil recovery is limited by the tendency of oil to adhere to surrounding mineral surfaces. Modern injection well techniques force fluids into the reservoir to enhance recovery by raising the hydrostatic pressure, but still leave behind a significant amount of the oil. Attractive intermolecular forces, especially van der Waals forces, are responsible for these inefficiencies; however, the relative strength of electrostatic repulsion in the solution also plays a role. This study seeks to maximize oil recovery by determining the factors that lead to adhesion at the nanoscale, thus allowing for optimized recovery techniques to be employed.
Atomic force spectroscopy provides direct and precise measurements of the oil-mineral interactions taking place in a simulated reservoir environment. The use of crude oil and sandstone grains from actual oil reservoirs keeps the experiment more analogous to the native conditions. In our experiments, an oil-functionalized probe is approached to the mineral surface in a liquid environment and then promptly retracted, and the active forces can be assessed with piconewton (pN) resolution. Our results show that solution composition directly affects the interactions between oil and rock.
In particular, Experiments 13 and 18, run with a dry oil-coated probe on a “K” sandstone grain produced adhesion values that were up to 1 nN lower in the low salinity brine. Also, the initial response of the probe in more than 85% of low salinity, “K” grain approach curves were categorized as repulsion, and only the low salinity curves of Ex. 8 showed repulsion at 10 nanometers, which averaged 3 pN. Given that these experimental conditions are designed to reproduce an actual reservoir on a small-scale, it is predicted that a low salinity waterflood would generate increased levels of oil recovery.
Knox, Jeffrey S., "Study of Oil-Mineral Interactions by Atomic Force Spectroscopy" (2014). Undergraduate Honors Theses. William & Mary. Paper 10.
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