Observing Dynamic Surface Chemistry and its Relevance to the Oil Recovery Problem
Research seminar abstract
Current industrial processes for recovering crude oil from microporous underground reservoirs are inefficient and recover only 30-50% of the oil that was originally contained within the reservoir.1 The oil recovery process is inefficient largely due to unfavorable interactions between surfactant species that are native to the oil phase and the oil reservoir structure.2 Presence of divalent cation species in connote brine water that coexists along with oil can increase the occurrence of the unfavorable oil/reservoir rock interactions.3 Efficient recovery of crude oil from underground microporous reservoirs requires that the unfavorable interactions involving the oil phase and cations be controlled by modification of geological structure’s surface chemistry.3, 4 Surface chemistry can begin to be investigated using microfluidic devices due to spatial similarities between the microporous structure of oil reservoirs and microfluidic devices. Similar to a reservoir, the functionality and performance of microfluidic devices is largely dictated by surface chemistry. Unfortunately, although the importance of surface chemistry is recognized in microfluidics, dynamic interactions occurring at the surface are not well understood.5, 6 To better understand the dynamic interactions within an oil reservoir, zeta potential changes at a polydimethylsiloxane/aqueous interface for an oil relevant surfactant (2-naphthoic acid) and salts (NaCl and CaCl2) were explored. Zeta potential was measured using the current-monitoring method applied to dynamic changes.7 It was observed that the surfactant and cations produce an increase and decrease in surface charge, respectfully. The changes in surface charge were obtained dynamically, and the change in surface charge was plotted as a function of time. Interestingly, when both the surfactant and divalent species are present, an increase in surface charge was observed but the rate and absolute increase was dependent on the concentrations of both the surfactant and divalent cation. These studies can provide important insights into dynamic processes that control oil retention in reservoirs. To further study interactions within an oil reservoir, accurate representations of the physical microporous structure are also required.8 The ability to experimentally test the oil recovery process and record quantitative visual data is restricted as a result of the limited availability of comprehensive pore-throat models. To model the flow that occurs within an oil reservoir the microfluidic Flow On Rock Device (FORD) was created using thin-sections of oil reservoir cores. Core flooding experiments carried out with the FORD showed unique results depending on both the geological characteristics of the core sample used (sandstone or shale) and initial wetting conditions (oil or water-wet). Although fundamental information regarding dynamic oil reservoir relevant surface chemistry and physical modeling will be discussed during the seminar, this research and information concerning surface chemistry is relevant to all areas of microfluidics and where surface chemistry significantly contributes.
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- Mark, D. et al. Microfluidic lab-on-a-chip platforms: requirements, characteristics and applications. Soc. Rev. 2010, 3, 1153–1182.
- Huang, X. et al. Current-monitoring method for measuring the electroosmotic flow rate in capillary zone electrophoresis. Chem. 1988, 17, 1837–1838.
- Bowden, S.A. et al. Recreating mineralogical petrographic heterogeneity within microfluidic chips: assembly, examples, and applications. Lab on a Chip. 2016, 24, 4677–4681.
Speaker: Chase Gerold
Speaker Institution: Colorado State University
Event Date: 03-31-2017
Event Time: 4:00 PM
Event Location: Chemistry A101
Mixer Time: 3:45 PM
Mixer Location: Chemistry B101E
Host: C. Henry