Understanding the Interactions at Rock-Water and Oil-Water Interfaces during Controlled-Salinity Water Flooding
Bibliographic record
Abstract
Abstract Over the years, laboratory studies and a limited number of field trials have demonstrated the potential of enhancing oil recovery using controlled-salinity water flooding. The injected brine composition is one of the promising techniques that could alter the wettability of carbonate rocks by changing the concentration of the potential determining ions (PDIs), specifically Ca2+, Mg2+, and SO42− ions. In this study, a comprehensive experimental study was conducted to investigate the rock-fluid and fluid-fluid interactions at rock-water and oil-water interfaces. The first step of the study was to measure the interfacial tension (IFT) using the spinning-drop tensiometer and study the dynamic behavior of the oil-water interactions. The zeta potential of carbonate rock samples was then measured using a specially-designed zeta potentiometer capable of utilizing the whole core plug, rather than the pulverized samples. The streaming potential technique was used for the zeta potential measurements and the experiments were conducted under different modified brine composition and rock saturation conditions. Subsequently, wettability alteration experiments were conducted using a specially designed high-pressure high-temperature (HP/HT) cell. The IFT measurements showed an increasing trend as salinity decreases, clarifying that rock-water interactions are more dominant over oil-water interactions. Results of the zeta potential experiments showed a clear trend of yielding more negative values as the seawater gradually diluted down to 1%dSW, due to the expansion of the electrical double layer. On the other hand, when the brine composition was modified, the increase of the PDIs (Ca2+ and Mg2+) did not have as much impact on zeta potential as the SO42− ions. In the wettability alteration experiments, both diluted and composition-modified brine generated a higher imbibition rate, resulting in a higher total oil production when compared with the experiments using the seawater. Furthermore, the wettability alteration of the rock surface trended more towards water-wetness conditions, as inferred from the contact angle measurements. The measurement of zeta potential before and after wettability alteration tests showed that the zeta potential value became less negative after the experiment, which suggested the expulsion of oil from the rock. This was further verified by the measurements of zeta potential for the unsaturated rock and saturated rock with brine and oil. The findings from this study would provide a better understanding of the rock-fluid and fluid-fluid interactions during controlled-salinity water flooding, which will benefit future studies in this area.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".