Experimental Study of Heavy Oil Recovery Mechanisms during Cyclic Solvent Injection Processes
Bibliographic record
Abstract
Summary The cyclic solvent injection (CSI) process has recently shown to be a promising method for enhanced heavy oil recovery in Canada. Laboratory testing is often run before development of field pilots to assess the effect of parameters, such as solvent choice and process conditions, on the CSI response. However, differences between laboratory results vs. field applications have been observed. CSI laboratory studies work for only two to three cycles due to low incremental oil in subsequent cycles, whereas field pilots continue for years over multiple cycles. This experimental study is intended to capture the production mechanisms responsible for heavy oil production in CSI. Primary production and CSI tests were conducted using sandpack models saturated with live heavy oil of 9530 mPa·s viscosity. The experiments were conducted in horizontal and vertical mode injection at high- and low-pressure depletion rates using two solvent mixtures of CH4 and C3H8. The sandpacks were scanned after every cycle to analyze the evolution of gas and oil saturations using computed tomography (CT). Three cores were used to study the effect of several parameters: gravity forces, pressure depletion rate, solvent composition, and initial oil saturation on the performance of CSI processes. CSI cycles run after primary production in horizontal systems produced negligible incremental oil for both slow and fast drawdown rates due to the large void space and high free gas saturation inhibiting the pressure buildup to push the solvent-diluted oil. These CSI experiments were only initially successful in dead oil systems, in which the initial oil saturation was higher and appropriate pressure gradient was generated through fast depletion rates. During the vertical alignment, CSI cycles exhibited higher incremental oil recovery per cycle. Slow depletion cycles were more efficient in terms of pressure and incremental recovery per cycle; however, faster depletion cycles performed better as a function of time. These results are more in line with the repeated recoveries measured over multiple cycles in field CSI pilot studies. More volume of diluted oil was drained out of the core when the solvent mixture with higher propane (C3H8) content was injected. These results demonstrate the importance of gravity drainage in the CSI process and its significance on successful oil recovery rates. This study illustrates the limitations of previous horizontal laboratory tests and shows an improved test configuration for modeling and prediction of the improved response observed in CSI pilots.
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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 | 0.000 |
| 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) | 0.000 | 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".