Bibliographic record
Abstract
This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 117489, "SAGD Gas Lift Completions and Optimization: A Field Case Study at Surmont," by T.C. Handfield, T. Nations, SPE, and S.G. Noonan, SPE, ConocoPhillips, prepared for the 2008 SPE International Thermal Operations and Heavy Oil Symposium, Calgary, 20-23 October. The paper has not been peer reviewed. Gas lift completions for steam-assisted-gravity-drainage (SAGD) producers are unique. Conventional gas lift valves and mandrels with a packer completion cannot be used because of the extreme temperatures of the downhole environment. Most lift gas enters the production stream downhole through open-ended tubing or nozzles, which, if not properly sized, can result in operational issues that negatively affect the overall lift efficiency. Data were collected and analyzed to determine the efficiency of two types of gas lift nozzles used in the completions. The method for optimizing SAGD gas lift systems is presented, and recommendations are made for future improvement. Introduction Surmont, an oil-sands project, is approximately 37 miles southeast of Fort McMurray in the Athabasca oil sands in Canada. The Surmont pilot began steam injection in 1997, comprising three SAGD-well pairs that use a variety of artificial-lift methods. These wells were tested to determine the preferred method of artificial lift for the first commercial phase. Main steam injection was initiated in mid-2007, and conversion to full SAGD production followed in late 2007. Phase 1A comprises 20 well pairs in which all the producers were completed to produce by use of gas lift for the initial life of the well. Phases 1A, 1B, and 1C have a capacity of 25,000 B/D and are expected to reach peak production in 2012. A second phase is slated for commercial startup before the middle of the next decade, which, upon completion and full ramp-up, is estimated to bring peak production from both phases to 100,000 B/D. Additional phases at Surmont are under study. Historical Perspective The Surmont gas lift experience began with trials in two of the three pilot wells. The completions consisted of a single production string varying in size from 3.5 to 5.5 in. with a 1-in. coiled tubing (CT) run concentrically for gas lift and landed at the heel of the well. The bottom 2 m of the gas lift string was constructed similar to a perforated stinger with ten 11-mm orifices. These gas lifted wells operated with reservoir pressure as low as 334 psi, producing fluid rates between 1,047 and 3,352 B/D, with gas lift rates ranging from 211 to 339 Mscf/D for a total combined operating time between the two wells of 35 months. The conclusion from testing at the pilot was that gas lift at the higher reservoir pressures was effective. However, before making additional designs and sensitivity studies, the gas lift assemblies were removed to allow for testing and validation of other forms of artificial lift for Surmont SAGD.
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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) | 0.000 | 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".