Preliminary Considerations on Application of Steamflooding in a Toe-to-Heel Configuration
Bibliographic record
Abstract
Abstract With the advent of horizontal wells, a distinct change is tacitly taking place in our approach to the improved recovery of heavy oil—from displacing mobilized oil in a flood pattern from injector to producers over long distances on the order of hundreds of metres to short-distance oil displacement (SDOD) processes (typically over a few tens of metres). SDOD processes comprise Steam Assisted Gravity Drainage (SAGD), Cyclic Steam Stimulation (CSS) and Toe-to-Heel (TTH) Displacement Processes, which comprise Toe-to-Heel Air Injection (THAI), with its variant catalytic THAI (CAPRI), and Toe-to-Heel Waterflooding (TTHW). Presently SAGD is commercially used, while THAI has been under field testing for 3 years; testing of CAPRI is scheduled to start in 2010. TTHW has been under field testing both in the US and Canada for more than 4 years. Steamflooding in a TTH configuration (TTH steamflooding) uses vertical wells as injectors and horizontal wells as producers, arranged in a staggered line drive, with producers having their toes close to the shoes of vertical injectors; the horizontal section of producers is located at the base of the pay. The vertical wells are used for initiating the steam front, which subsequently is anchored at the toe of the horizontal producer; it is then propagated towards the producer's heel. In TTH steamflooding, the existing deficiency of conventional steamflooding schemes in terms of low vertical sweep is overcome by the beneficial use of gravity. To investigate the potential of TTH steamflooding, some laboratory tests were conducted. The objective was to assess the feasibility of TTH steam and thermo-solvent flooding (steam+propane co-injection) by carrying out 3D model experiments using heavy oil with a viscosity of 15,000 cP. Laboratory results showed that the concepts of TTH steamflooding and TTH steamflooding with solvent are feasible. All in all, stability of TTH steamflooding was relatively good, while the stability of TTH steamflooding with the addition of nitrogen or propane was much better. Significant improvements in design and operation of these processes were needed in order to promote override during the early phase, and obtain a stable and efficient process. The improvements included a cold (gas fingering) and a hot (steam-based) communication phase; and controlling lateral spread of steam by using two additional vertical control wells (positioned laterally but close to the heel of the horizontal producer) for conducting a limited steamflood. Nitrogen was injected along with steam in the conventional steamflood; propane replaced nitrogen in TTH steamflooding with solvent.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.002 |
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".