Pressure Build-up and Decay in Acid Gas Injection Operations in\n Reefs in the Zama Field, Canada, and Implications for CO
Bibliographic record
Abstract
\n The objective of this paper is to examinereasons for pressure rise in the Zama X2X pool\n in northwestern Alberta, Canada, that was used foracid gas disposal, and whether\n subsequent pressure decay was a result of pressure dissipation into a larger aquifer. The\n Zama X2X pool, approximately 1 km2 in size, is connected to four other nearby\n poolsthrough a common underlying aquifer. Pressure analysis for all the pools indicates\n that they are in goodhydraulic communication. Initial pressure in the Zama X2X pool was\n approximately 15 MPa. Pressuredeclined first during oil production, stabilizing at around\n 10 MPa in the early 1970s, after which started toincrease such that it reached 26 MPa in\n 1986. Subsequently, pressure declined reaching 22 MPa by 1995just prior to starting\n injection of acid gas (80% CO2 and 20% H2S). The operator injected\n acid gas at lowerrates and wellhead pressures than those licensed by the regulatory\n agency. Despite significant production ofwater and hydrocarbons, the pressure in the Zama\n X2X pool continued to be higher than the initial reservoirpressure by more than 5 MPa,\n such that disposal operations were suspended in late 1998. Oil productioncontinued all\n this time until 2002. \n Numerical simulations using CMG-IMEXTM and corresponding sensitivity\n studies reported in this papershow that disposal of more than 1 million m3 of\n water between 1970 and 1988 and again in 1992-1993 inthe adjacent Zama YY pool, which is\n in good hydrodynamic communication with the Zama X2X poolthrough the aquifer below the oil\n column, is the main reason for the high pressures observed in the ZamaX2X pool.\n Sensitivity studies indicate that pressure decay in the X2X pool was due to fluid\n production.The study indicates that while pressure rise has been caused by hydraulic\n communication between theX2X and YY pools through the common aquifer, the aquifer was not\n of large volume to allow dissipationof the pressure. In addition to the case study, the\n implications of pressure communication to geological storage of CO2 in aquifers\n are briefly discussed.\n
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".