Improved Channeling and Gas Migration Issues Using Foam Cement: Case History, Montney Formation
Bibliographic record
Abstract
Abstract Wells in the Montney Formation area, British Columbia, Canada, were designed as monobores and include surface and long lateral production casings. The decision to modify the openhole (OH) completion to a cemented sleeve system presented some concerns. A comprehensive data set from all prior cement operations was compiled and analyzed. This data showed severe gas migration to surface for both an OH completion and cemented lateral well. Computational fluid dynamics (CFD) and a finite-element simulator were used to evaluate both conventional and foam cement options using actual centralization and caliper log data. The results from this analysis identified a gas-flow potential factor (GFP) was of an order of magnitude where only compressible, foam cement would provide the required properties to achieve competent, long term zonal isolation. The characteristics of foam cement include a high kinetic energy that assists removing immobile mud trapped on the low side of the casing. Additionally, in this case, using a foamed spacer further improved mud removal from the annulus, resulting in improved displacement efficiency, as observed in the final cement evaluation logs. Filtrate loss and reduced hydrate volume can allow gas migration, giving rise to surface casing vent flow (SCVF) while the cement is curing. Foamed cement helps create a highly compressible cement system that can compensate for these volume decreases and reduce the potential for SCVF. The ductile properties of the set foam cement help mitigate the likelihood of cement debonding and cracks forming during hydraulic fracturing operations, which also helps to reduce the potential for SCVF.
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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 | 0.001 |
| 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".