Investigation and Observations on the Stability of Water-Oil Ratio WOR during Chemical Floods in Heavy Oil Reservoirs
Bibliographic record
Abstract
Abstract Long periods of up to several years of production at a Water-Oil Ratio (WOR) at or close to 1 have been observed in polymer floods in heavy oil reservoirs in Western Canada. A similar behavior had been noted by some authors in waterflood projects in heavy oil; however, this has never been documented in chemical floods before. Such long periods of WOR stability at low values, with very unfavorable Mobility Ratios, are not expected from theory. The aim of this paper is to review chemical floods in heavy oil reservoirs in Canada to better understand this phenomenon and try and identify the potential mechanisms by investigating reservoir and operational factors. If the phenomenon can be controlled through adequate operational practices, it would allow to operate chemical floods under very favorable WOR conditions for long periods. The production data of hundreds of wells in 8 large scale polymer and ASP floods in heavy oil reservoirs in Western Canada has been reviewed to investigate the occurrence of periods of stable WOR close or equal to 1. A significant number of wells that display this kind of behaviour were identified and studied. The impact of Gas Oil Ratio, oil viscosity, injection rate and other factors was analysed to try and identify some potential factors causing the phenomenon. Long periods of WOR stability at or around 1 have been confirmed in 3 of the 8 chemical floods reviewed; 2 cases are polymer floods and 1 is a mixed polymer/ASP flood. The behaviour has been observed during primary, secondary as well as tertiary polymer flood. There appears to be a link with the injection and liquid production rates i.e. WOR stability occurs in a given range of rates; but no other obvious factors have been identified so far. The existence of long periods (up to several years) of WOR stability around 1 is documented for the first time in chemical floods in heavy oil reservoirs. This behavior is unexpected from theory and deserves further study; if it could be controlled through adequate operational practices, it would allow to operate chemical floods under very favorable WOR conditions for long periods.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| 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 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".