Heavy-Oil Recovery in Naturally Fractured Reservoirs with Varying Wettability by Steam Solvent Co-Injection
Bibliographic record
Abstract
Abstract In heavy-oil recovery, although steam injection has no alternative in many circumstances, it may not be an efficient process under certain reservoir conditions. These conditions include deep reservoirs, where steam injection may turn out to be ineffective hot-water flooding due to excessive heat loss, and oil-wet fractured carbonates, where steam channels through fractures without effectively sweeping the matrix oil. Solutions for heavy oil recovery in consolidated/unconsolidated sandstones have been proposed and some of them are currently in the commercial phase, including steamflooding and its different versions. A more challenging case is heavy-oil fractured carbonates where the recovery is usually limited only to matrix oil drainage gravity due to unfavourable wettability or thermal expansion if heat is introduced during the process. Wettability alteration is usually thought to occur at elevated temperatures which are difficult to achieve in deep reservoirs. Thus, improvement of matrix oil recovery requires different methodologies. We propose a new approach to improve steam/hot-water injection effectiveness and efficiency for this type of reservoir. Static imbibition experiments were run on Berea sandstone and carbonate cores with different wettabilities and for different oil viscosities ranging between 200 cp and 14,000 cP. For wettability alteration, cores were either aged or treated by a wettability altering agent. The experiments were conducted initially in imbibition cells in a 90 °C oven to mimic the matrix-fracture interaction in steam condensation zones. Due to its high boiling point, heptane was selected as the solvent and the core samples were exposed alternately to high temperature imbibition and solvent diffusion. The main ideas behind this process were to enhance capillary and gravity interaction by reducing viscosity (heat and solvent effect) and altering wettability (solvent effect). The results showed that further reduction in oil saturation due to s solvent diffusion process preceded by hot water is remarkably fast and the ultimate recovery is high. The magnitude of recovery depends on wettability and the amount of water existing in the core. It was also observed that solvent retrieval is a very fast process and may increase to 85-90% depending on core type, wettability, and saturation history.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".