Some Lessons on Application of Horizontal Wells from the Western Canadian Experience
Bibliographic record
Abstract
Abstract Horizontal wells are usually drilled as development wells with a motivation to recover incremental oil and to accelerate production. In other words, they are meant to access and recover oil from certain locations such that 'poorly-floodable' and otherwise 'poorly-drainable' oil ultimately left behind in the reservoir, is significantly reduced. Clearly, their suitability is linked to reservoir characteristics, heterogeneity and reservoir mechanisms. In many (but not all) situations when infill wells are economically viable, horizontal wells significantly enhance return on investments. They are important to Canada as one study1 estimated potential incremental oil reserves due to horizontal wells at 450 million cubic meters (2.8 billion barrels). A recent study of about 12,000 horizontal wells drilled in the Western Canadian Sedimentary Basin over the last decade2 revealed that an average horizontal well added reserves by roughly twice over that added by an average offset vertical well drilled in the same pools and over the same period. If the average cost of a horizontal well was also higher by a factor of two, this points to identifying situations where horizontal infill wells would be more cost-effective. It may also be pointed out that other (but earlier) studies3,4 suggested that about one out of three horizontal wells in Western Canada would not be profitable. Economic success rate for vertical development wells in the basin, on the other hand, is usually assumed to be in the 80 to 85% range. This paper reviews many aspects of the observed success/failure of horizontal wells in different regions of Western Canadian Sedimentary Basin. It is emphasized that whereas horizontal wells offer many advantages, it may be prudent in many situations to drill vertical rather than horizontal infill wells, in view of various uncertainties about reservoir characteristics and risks involved.
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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 | 0.005 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.004 |
| Science and technology studies | 0.010 | 0.005 |
| Scholarly communication | 0.005 | 0.003 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.008 | 0.001 |
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".