Micro Visual Investigation of Polymer Retention in a Micromodel
Abstract/Contents
- Abstract
- An objective of this research is to develop new experimental techniques to visualize polymer retention on the solid surfaces of porous media. Three retention mechanisms are investigated: hydrodynamic retention on rock surfaces, mechanical entrapment in pore matrices, and the formation of immobile micro-gel. Two-dimensional micromodels with uniformly constructed and well-characterized pore networks were exclusively used as the representation of simplified porous media. In single-phase flow experiments, the retention of partially hydrolyzed polyacrylamide (HPAM) polymers with a concentration of 2000 ppm was examined visually. Image analysis including an image subtraction and an RGB-based global thresholding technique has been utilized for the visualization of the polymer retention / adsorption and measurement of numerical values of percent polymer retention. The three factors, which are the salinity of displacing water, the change of wettability of the micromodel surface, and mechanical degradation of polymer, influencing the polymer retention were investigated. First, the effect of salinity in displacing water on polymer retention was studied and experimental results confirmed that five percent NaCl concentration in displacing water results in lower polymer retention (6.34%) than the value (7.47%) of polymer retention without NaCl. The increase in Na+ concentration was sufficiently high to induce the contraction of the size of the flexible HPAM molecules, hence decrease the thickness of polymer adsorption on the grain wall. Second, two methods were used in order to change wettability of the surface of the micromodel, that is strongly water-wet at initial state. Wettability of the micromodel surface was changed by the deposition of Haradh Saudi Arabia crude oil and CTAB (cetyl trimethylammonium bromide).The micromodels treated by crude oil and CTAB showed polymer retention of, 15.04% and 5.04%, respectively. Third, the effect of filtration of polymer solution through a 7 µm filter was tested and the filtered polymer has the average percent polymer retention of 4.26%, which is 3.21% lower than the value of unfiltered polymer solution. Image analysis permitted observation of the inhomogeneous portion of polymer, ie. microgels, that is trapped in the pore network of micromodels. Further investigation of microgels provided a chance to demonstrate a size and structural flexibility of microgel leading to a transition from mobile to immobile conditions. This experimental study illustrates the successful application of the silicon-wafer micromodel device with interpretation using image processing techniques. It also provides a useful reference for the pursuit of more fundamental and visual understanding of polymer retention mechanisms.
Description
| Type of resource | text |
|---|---|
| Date created | June 2014 |
Creators/Contributors
| Author | Yun, Wonjin |
|---|---|
| Primary advisor | Kovscek, Anthony R. |
| Degree granting institution | Stanford University, Department of Energy Resources Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Genre | Thesis |
Bibliographic information
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Preferred citation
- Preferred Citation
- Yun, Wonjin. (2014). Micro Visual Investigation of Polymer Retention in a Micromodel. Stanford Digital Repository. Available at: https://purl.stanford.edu/sx783qr4650
Collection
Master's Theses, Doerr School of Sustainability
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