Novel Schemes for Improving Recovery Factor of Ultra-thin Low-permeable Sandstone Reservoir by CO2 Flooding, Case Study: CCUS project in V Reservoir, Canada
Bibliographic record
Abstract
The V reservoir is ultra-thin, low-permeable sandstone with net pay of less than 3m and air permeability of 5.1 mD.Its primary recovery is 10% of OOIP due to low permeability and high heterogeneity.CO2 miscible flooding has been implemented since 1998 to improve oil displacement and increase oil production.This paper discusses a case study on the field to show effect of a new CO2 EOR scheme.This paper presents a CO2 flooding development plan specifically tailored to ultra-thin sandstone reservoirs with strong heterogeneity.A modified line drive flood pattern was designed to make full use of the monocline structure of the reservoir.Moreover, the development plan minimized the adverse effects of gravity segregation by injecting CO2 at the structurally high part of the reservoir and producing oil at the low part.The injection-production well pattern is designed to overcome facility constraints by placing vertical producers in the thicker part of the reservoir sand body, while horizontal producers in the thinner part of the edge sand body.The method of water-alternating-gas (WAG) injection was adopted to improve the sweep efficiency and have a better conformance control in the late stage of CO2 flood.The actual production results of the oilfield show that with the new CO2 flooding development plan, the recovery rate has increased by 22%, and the daily oil production has also increased from approximately 10 m3/d before the implementation of the plan to 100 m3/d approximately.After historical matching, the dynamic model statistical calculation results of the reservoir numerical simulation also show that the CO2 miscible sweeping volume reaches more than 82% of the total sand volume.It is predicted that the ultimate recovery factor can reach higher than 50%.The above good oil displacement effect comes from the effectiveness of the following methods.The monocline structure has a favorable dip angle creating a gravity overriding effect on CO2 flood.When CO2 is injected at the high structure and migrates to the low structure, it fully interacts with the crude oil, boosting oil recovery.Horizontal wells are used in thin sand formations to significantly maximize contact with the reservoir and enhance oil flow.The technique of alternating gas and water injection is used with dynamically adjusted pressure to create a "gas lock," blocking high permeability areas and reducing gas channeling.This paper depicts the guidance to efficiently develop the ultra-thin, low-permeable reservoir.The new scheme includes methods such as injecting CO2 into the high part of the reservoir and producing oil at the low part, using horizontal wells to produce thin sand bodies at the edge, and dynamically adjusting the gas and water alternating injection pressure to reduce gas channeling.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".