Study of Alkaline/Polymer Flooding for Heavy-Oil Recovery Using Channeled Sandpacks
Bibliographic record
Abstract
Summary For heavy oils with viscosities ranging from 1000 to 10 000 mPa·s in western Canada, primary production and waterflood together can recover only 8–15% of original oil in place (OOIP) at their economic limits because of the adverse mobility ratio, severe water channeling, low reservoir pressure, and formation voidage. These heavy oils usually have a relatively high content of acids that can react with alkalis to form in-situ surfactants. The loosely consolidated sandstone formations in which these oils are deposited are characterized by high porosity, high permeability, and low reservoir temperature. These reservoir conditions are favorable for polymer application. Therefore, there is a potential to improve waterflood in these reservoirs by applying alkaline/polymer (A/P) flooding. This paper presents the results of a laboratory study of A/P flooding for heavy-oil recovery, including viscosity measurements, flood tests conducted in channeled sandpacks, residual-resistance-factor (FRR) determination, and residual-oil-distribution tests. A heavy oil with a viscosity of 1,202 cp and an acid number of 1.07 (mg of KOH/g of oil) and produced brine collected from a heavy-oil reservoir in Alberta are used in this study. We found that the distribution of the injected chemical solution within the high-permeability channels leads to the diversion of the subsequently injected chemical solution to low-permeability zones with higher oil saturation because of the formation of blockage in the channel zones. Consequently, pressure buildup during chemical-slug injection is the key to the improvement of displacement efficiency. Flood tests also show that A/P flooding is more efficient than either alkaline flooding or polymer flooding. The optimal formulation for the heavy oil used in this study is 0.4% NaOH + 0.2% Na2CO3 + 1000 mg/L polymer, with a tertiary oil recovery of 25–30% of OOIP above that from waterflooding. Analysis of the results of the residual-oil distributions in the channeled sandpacks at the end of A/P flooding show that A/P flooding can effectively improve the sweep efficiency of waterflooding for the heavy oil.
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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 | 0.000 |
| 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 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".