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| Main Authors: | , , , , , , , |
|---|---|
| Format: | Recurso digital |
| Language: | English |
| Published: |
Zenodo
2023
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| Subjects: | |
| Online Access: | https://doi.org/10.5281/zenodo.16199032 |
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Table of Contents:
- <p>Executing a successful waterflood recovery project in the field requires prior laboratory core flooding studies in order to understand fluid displacement and predict the recovery efficiency. When dealing with reservoir rocks that display complex fluid distribution (for example due to pore size heterogeneity, capillary end effect, or wettability heterogeneity), the use of an imaging technique is crucial. Traditionally, fluid saturation changes during core floods are monitored using X-Rays. However, the use of dopants is usually required in order to improve the density contrast between fluids. These dopants may alter the wettability of the rock or could chemically inhibit some EOR operations, such as low salinity injection. In this work we introduce a simple Magnetic Resonance Imaging measurement to monitor hydrocarbon saturation profiles. This measurement, selective for hydrocarbons, requires no contrast agents or unusual fluids. We employ Carbon-13 measurements of carbon in the hydrocarbon phase to directly detect oil with natural abundance 13C. This allows for spatial quantification of oil saturation in core plug samples. The core plugs tested were water-wet Berea and Bentheimer sandstones and oil-wet (treated) Bentheimer sandstones. Viscosity standard oils were used as the oil phase, and brine (2.1 wt% NaCl) was used as the water phase. Imaging was performed using the 1D Hybrid SE-SPI MRI method. The results showed that the 13C 1D images provided high quality saturation information. Dean-Stark analysis on the final state of the core plugs confirmed the saturations. The 13C bearing phase was directly observed, and there was no need for further processing to separate the signals. Flooding in different combinations of fluids, rocks, and wettability conditions was examined by 1D imaging. The 13C profile method clearly reveals hydrocarbon capillary end effects in oil wet samples. The ability to generate direct 13C profiles is a general capability which is applicable to a wide range of flooding experiments and core analysis measurements. In particular, it provides an alternative to the common use of D2O in profile MRI studies to eliminate observation of the water phase. These studies are greatly facilitated by a variable field magnet which permits sequential measurement of 1H and 13C in the same magnet with the same RF probe.</p>