Reserves growth in a mature oil field: The Devonian Leduc Formation at Innisfail field, south-central Alberta, Canada
Bibliographic record
Abstract
Abstract Oil has been continuously produced from the Devonian Leduc Formation at Innisfail field since its discovery in 1957. To date, cumulative production at Innisfail is 98.9% of recoverable oil in place (84.3 MMBO) and indicates that the Leduc is near the end of its productive life. A sequence-stratigraphic interpretation produced from core, well logs, and three-dimensional (3-D) reflection seismic data, however, suggests that production may be extended through the development of two previously undetected scenarios of bypassed oil entrapment: (1) attic oil accumulations associated with small buildups atop the isolated Innisfail platform and (2) backstep-edge accumulations located in positions structurally low to currently producing wells. In both cases, oil accumulations are related to a Leduc depositional history that was characterized by rates of long-term carbonate sediment accumulation exceeded by the rate of sea level rise. Positive bathymetric relief created at the time of deposition and, subsequently, present-day stratigraphic traps were produced during the final phase of stratal retrogradation that immediately preceded the drowning of the isolated Innisfail platform. High-quality 3-D seismic data are essential in the exploration for both attic and backstep-edge oil accumulations at Innisfail. Integration of 3-D seismic data, well-log, and core data indicates that although depositional relief on both types of features may be low, they are nonetheless seismically resolvable. The small platform-top buildups are up to 0.16 km2 (40 ac) in diameter and have up to 10 m (33 ft) of independent closure above spill point. Backstep-edge oil accumulations occur within the structurally highest parts of the Leduc high-frequency sequence G downlap limit. Depositional relief along the downlap limit and associated trap closure ranges from approximately 5 to 15 m (16 to 49 ft). During 2003 and 2004, two platform-top buildups were directionally drilled, and one existing well located near a backstep-edge position and suspended since 1988 was reactivated. All three wells are successful and, to date, have cumulative production of 71 thousand bbl of oil. A total of 17 platform-top buildups and backstep-edge development drilling prospects exist across Innisfail and have expected-case recoverable reserves of approximately 960 thousand bbl of oil. These reserve additions suggest the potential for 1.14% field growth at Innisfail and are representative of the potential value that may yet exist within all mature Leduc fields in western Canada.
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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) | 0.001 | 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 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".