Minireview and Perspectives of Gas–Rock Interactions in Shale Reservoirs for Symbiotic Storage of H <sub> <b>2</b> </sub> and CO <sub> <b>2</b> </sub>
Bibliographic record
Abstract
Shale formations are increasingly considered for the symbiotic storage of CO 2 and H 2, where permanent carbon sequestration is combined with flexible energy storage. This review focuses on gas–rock interactions in shale and examines how geochemical reactions, pore structure evolution, and mechanical property changes influence containment and storage performance in a symbiotic gas-storage scenario. A synthesis of recent laboratory and modeling studies shows that CO 2 strongly interacts with carbonate, feldspar, and clay minerals, leading to dissolution, secondary mineral precipitation, and swelling. Adsorption capacity under reservoir pressure conditions was observed to typically range from 0.5 to 3.5 mmol g –1 and porosity may increase from 1.4% to 3.5% after prolonged exposure to CO 2 . Moreover, it also leads to reductions in strength and stiffness from 30 to 45%. On the other hand, hydrogen exhibits comparatively lower adsorption capacity, generally ranging less than 0.05 mmol g –1 . It interacts weakly with shale through chemical pathways and yet affects rock integrity by promoting microcracking, softening, and transport through pore networks, especially in organic-rich zones. When both gases are injected, their effects are interdependent: CO 2 modifies mineralogy and sorption sites, which alters H 2 diffusion and migration pathways. Comparative analysis further indicates that CO 2 -related changes dominate over long time scales, while H 2 introduces additional challenges under cyclic injection withdrawal, raising questions about fatigue and seal reliability. Despite significant progress, critical knowledge gaps remain, such as long-duration CO 2 –H 2 exposure tests under reservoir pressure–temperature conditions, the role of microbial activity, and the upscaling of laboratory results to field operations. Future research should focus on integrated experimental and modeling approaches that capture these coupled processes and provide a basis for evaluating shale formations as a safe dual-purpose storage medium.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.014 | 0.004 |
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".