Bitumen Recovery from Carbonates by Modified SOS-FR (Steam-Over-Solvent Injection in Fractured Reservoir) Method Using Wettability Alteration Chemicals
Bibliographic record
Abstract
Abstract Application of primary and secondary recovery processes in naturally fractured carbonate reservoirs containing heavy-oil/bitumen usually results in no or low recovery. Hence, an enhanced oil recovery (EOR) method is typically needed at early stages. Changing the characteristics of rock/fluid system, such as wettability and interfacial tension, in such challenging reservoirs becomes critically essential in this attempt. Recovery from the Grosmont carbonate unit is further complicated by the immobility of bitumen as well as extreme reservoir heterogeneity. This specific reservoir requires either pre-heating or solvent dilution before any further EOR attempts. This study investigates the applicability of the modified version of the previously proposed SOS-FR (steam-over-solvent injection in fractured reservoirs) method to recover bitumen from the Grosmont carbonate unit. Using the suggested methodology, three phases were applied on a total of 13 preserved core samples from this unit. In Phase-1, the cores taken from three different formations of the Grosmont unit were soaked into a liquid solvent (heptane or distillate) at ambient conditions. Depending on the quality of the bitumen, a certain amount of recovery was obtained. The original form of the SOS-FR method was based on steam (or hot-water) injection at the temperature near the boiling point of the solvent as the following phase to retrieve the solvent. In Phase-2, instead of this "thermodynamic" approach, we tested an "interfacial" approach and soaked the samples into water with chemicals additions. Wettability modifiers tested include high pH solution, surfactants and ionic liquids, which were screened in our earlier work (SPE 170034) and selected as the most useful wettability alteration chemicals for oil-wet carbonates. One of the key benefits of the ionic liquids is that they are environmentally friendly and can be customized for particular rock/fluid system while pH solutions are economically attractive. Phase-2 was applied at room temperature and at 65°C. Finally, Phase-3 was applied by increasing temperature to the bubble point of the solvent to mimic hot-water injection with chemicals. Each phase was analyzed in terms of ultimate oil recovery (and wettability alteration), time to reach this amount, the most suitable wettability alteration chemicals, and soaking times needed. The results revealed that the solvent phase not only affects the bitumen properties, but also changes Grosmont rock characteristics significantly. Wettability alteration of the fractured Grosmont reservoir was observed to be highly critical, not only for additional oil recovery but also for solvent retrieval. Specific high pH solution was observed to efficiently alter wettability and recover considerable amount of bitumen/solvent mixture fairly quick showing a potential as a low cost chemical to recover bitumen. The results and discussion on the optimization of the process in terms of the solvent soaking period, wettability alteration chemicals, and the effect of temperature will be useful for further field EOR attempts.
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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".