Bibliographic record
Abstract
Abstract This paper summarizes evidence of gas effects in several Athabasca SAGD projects. These effects are easily reproduced with simple 1D column simulations. Solution gas has a material impact on SAGD production rates in general, which explains the need to use arbitrarily low permeabilities when history matching with no gas in the model. Introduction Following the UTF Phase A SAGD test, it was reported that: "No significant accumulations [of noncondensible gas] were observed in the steam chamber. This was fortunate because such accumulations appear to be harmful because they inhibit steam transport to the front. "Current simulators incorrectly predict that even small amounts of gas…will accumulate in a steam chamber and substantially impair drainage…more work is required to account for gas transport mechanisms adequately so that reasonable predictions can be made for reservoirs containing greater amounts of gas."(1) Simulators still do not properly account for known amounts of solution gas in the McMurray formation, in the sense that is not generally possible to produce a reasonable history match of field behavior if the full amount of solution gas is included. (2) The question of how the gas is being removed from the chamber, and therefore what is missing from the simulators, remains unresolved, and is beyond the scope of this paper. Meanwhile, two important points have been passed over. The first is that, even at UTF, some in-significant gas accumulations can be found in the data, as reported for example by Ito. (3) The second is that "reservoirs containing greater amounts of gas", than UTF/Dover that is, includes most of the current McMurray SAGD projects. In the case of Foster Creek, at the deep end, saturation pressure is 2800 kPa and the solution GOR is estimated to be about 5 times that at Dover. Since the gas removal mechanism(s) is unknown, it has always been possible that it was strong enough under UTF circumstances to prevent "significant" accumulations, but not strong enough to do this in deeper Athabasca reservoirs. However, the difficult nature of the SAGD gas problem, combined with the apparent success of UTF history matching without it, has understandably encouraged a situation where it has become standard practise to ignore solution gas in SAGD simulations. Standard practice is also to arbitrarily lower absolute and/orrelative permeabilities in order to match field performance. In the case of the UTF, there was good correspondance between measured core and history match permeabilites, using "open" relative permeabilites. This correspondance does not seem to apply to deeper, thicker reservoirs such as Surmont or Foster Creek, particularly with respect to steam rise rates. Field Evidence Hangingstone Ito et al report detailed analyses and history matching of observation well temperature data from the UTF Phase B(3)and Hangingstone Phase I(4) projects. Although the Hangingstone situation is complicated by the high operating pressure of 5 MPa at a depth of 280 m*, they show anomalies in the rise rates at some wells, where steam rise would "suddenly stop" for a while and then resume.
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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".