Maximising CO2 sequestration efficiency in deep saline aquifers through in-situ generation of CO2-in-brine foam incorporating novel CO2-soluble non-ionic surfactants
Bibliographic record
Abstract
The geological sequestration of carbon dioxide (CO 2 ) within deep saline aquifers remains a critical pathway for achieving long-term climate stabilisation and net-zero targets. This study presents a novel strategy to augment both the efficiency and security of CO 2 storage through the in-situ formation of CO 2 -in-brine foams facilitated by non-ionic CO 2 -soluble propoxylated-ethoxylated alcohols surfactants, specifically 2EH-PO 5 -EO 9 and 2EH-PO 5 -EO 15 . A comprehensive suite of laboratory investigations was conducted under representative reservoir conditions (70 °C and 3200 psi), including cloud point pressure analysis, foam stability monitoring, interfacial tension (IFT) reduction, wettability alteration studies, CO 2 solubility measurements, and core flooding experiments. The results reveal that both surfactants exhibit strong solubility in supercritical CO 2 and brine, enabling stable foam generation without degradation. Among them, 2EH-PO 5 -EO 15 demonstrated superior performance, achieving a marked reduction in CO 2 –brine IFT, from 32 to 6.7 dyne/cm, and enhancing CO 2 solubility in brine by over 100 % (from 1.25 to 2.51 mol%) compared to pure CO 2 scenario; thus strengthening solubility trapping. In parallel, wettability characterisation showed a transformation of the sandstone substrate from strongly water-wet (θ ≈ 18°) to an intermediate gas-wet condition (θ ≈ 71°), significantly amplifying the potential for residual trapping. Core flooding assessments corroborated these synergistic effects, demonstrating reduced CO 2 mobility and improved sweep efficiency through foam stabilisation and rock–fluid interfacial modification. Altogether, this work underscores the efficacy of CO 2 -soluble non-ionic surfactants in enhancing storage security and injectivity, offering a technically and economically attractive approach to large-scale CO 2 sequestration in saline aquifers. Also, the current results establish a strong foundation for advancing toward field-scale implementation and represent a significant step forward in creating sustainable solutions for carbon management. • Improving CO 2 sequestration in the saline aquifers via generation of in-situ foam. • The application of novel non-ionic CO 2 -soluble propoxylated-ethoxylated alcohols surfactants. • CO 2 -soluble surfactants exhibit strong solubility in supercritical CO 2 and brine, enabling stable foam generation without degradation. • The strengthening CO 2 solubility trapping ocuured due to enhancing CO 2 solubility in brine and IFT reduction. • The wettability alteration to an intermediate gas-wet amplifying the potential for residual trapping.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".