Formation, distribution, oil-in-place, and recoverable reserves of heavy oil and extra-heavy oil deposits
Bibliographic record
Abstract
Most heavy and extra-heavy oils originate from conventional oils which have been subsequently degraded in shallow and porous reservoirs by one or several of the following processes: biodegradation, water washing, loss of volatiles, and inorganic oxidation. These processes result in a decrease of the light ends of the crude oil, and also of the alkanes and low molecular weight alkylbenzenes, and an increase of the more resistant polyaromatics, resins, and asphaltenes. Furthermore, at certain conditions, sulfur extracted from sulfate by anaerobic bacteria may react with hydrocarbons to increase the sulfur content. The extent of degradation is associated with depth, proximity to aerial contact, and salinity of formation waters. Excellent examples are provided by the two major provinces of heavy and extra-heavy oils, i.e., Eastern Venezuela and Western Canada. These provinces are situated in foreland-type basins. The basin frequently offer a large volume of mature source rocks. Then, the existence of a wide homocline slope, with a tremendous drainage area, and the occurrence of conductors, such as sandstone layers formed in a paleodelta system or major unconformity surface, favor a long-distance migration from the deep part to the end part of the basin. A wide drainage area is an essential condition for gathering a huge amount of oil into a single accumulation. Finally, degradation itself seems to be an important factor for trapping very large quantities of oil. The R/P of recoverable conventional oil is estimated as c.a. 64.5 years from the recoverable reserves and the additional quantities of conventional oil, which were estimated in 2002 by JPDA. Oil-in-place of heavy and extra-heavy oils are 2,044.3 billion barrels and 4,145.4 billion barrels, respectively, estimated by UNDP project in 1999. In addition, heavy oil of 717 billion barrels and extra-heavy oil of 724 billion barrels are considered as potential recovery. These figures correspond to the R/P c.a. 24.5 and c.a. 24.7 years, respectively. Therefore, total R/P of recoverable oil resource, conventional oil plus unconventional oil, exceeds 100 years.
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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 | 0.002 | 0.001 |
| 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".