Evaluation of Imbibition Oil Recovery in the Duvernay Formation
Bibliographic record
Abstract
Summary In this study, we evaluate the wettability of shale plugs from the Duvernay Formation, which is a self-sourced reservoir in the Western Canadian Sedimentary Basin. We use reservoir oil and flowback water (brine) to conduct air/liquid contact-angle and air/liquid spontaneous-imbibition tests for wettability evaluation. We characterize the shale samples by measuring pressure-decay permeability, effective porosity, initial oil and water saturations, mineralogy, and total-organic-carbon (TOC) content, and by conducting rock-eval pyrolysis tests. We also conduct scanning-electron-microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses on the shale samples to characterize the location and size of pores. After evaluation of wettability, we conduct soaking tests. First, we measure liquid/liquid contact angles for the droplets of the soaking fluids and reservoir oil equilibrated on the surface of the oil-saturated plugs. Then, we conduct soaking tests by immersing the oil-saturated plugs in different soaking fluids, and record the oil volume produced from spontaneous imbibition of the soaking fluids. The soaking fluids are characterized by measuring surface tension (ST), interfacial tension (IFT), viscosity, and pH. We analyze the results of soaking tests and investigate the controlling parameters affecting oil recovery factor (RF). The results demonstrate that the shale samples have stronger wetting affinity toward oil compared with brine. The positive correlations of TOC content with effective porosity and pressure-decay permeability suggest that the majority of connected pores are within the organic matter. The strong oil-wetness of the shale samples can be explained by the abundance of organic porosity, verified by the SEM/EDS images. The results of liquid/liquid contact-angle tests show that the soaking fluid with lower IFT exhibits a stronger wetting affinity toward the shale. The results also show that oil RF is higher for the soaking fluids with lower IFT, which may be caused by wettability alteration. In addition, comparing the results of air/brine imbibition with those of the soaking tests indicates that adding nonionic surfactant to the soaking fluid may alter the wettability of hydrophobic organic pores toward less-oil-wet conditions, leading to the displacement of oil from organic pores.
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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 | 0.007 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".