Experimental Investigation of CO-Based VAPEX for Recovery of Heavy Oils and Bitumen
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Bibliographic record
Abstract
Abstract Vapour extraction (VAPEX) has recently emerged as an attractive alternative to thermal recovery techniques for the huge resources of heavy oils and bitumen available in Canada, the USA and Venezuela. The current version of VAPEX relies on the injection of light hydrocarbon gases for reducing the oil viscosity. The economic viability of this process is very sensitive to the cost of injected gases in relation to the selling price of the produced oil. One attractive option for reducing the cost of injected gases appears to be the use of CO2 as a major component of the injected solvent. This modification will utilize mixtures of CO2 and propane as the solvent instead of the currently popular mixtures of methane and propane. Since CO2 is significantly more soluble in heavy oils than methane, it is likely that such mixtures will provide greater reduction in viscosity compared to equivalent mixtures of methane and propane. In this work, methane-propane and CO2-propane were investigated as solvents for the VAPEX process for in situ recovery of heavy oil and bitumen. Twelve laboratory experiments were performed with two types of oil [4,500 mPas and 18,600 mPas at 294.15 K (21 ºC)]. These tests were performed in a partially-scaled physical model at different operating pressures ranging from 1,469.3 kPa (200 psig) to 4,227.2 kPa (600 psig) and were designed to compare the performance of methane-based solvents with that of CO2-based solvents. The main conclusion from this study is that the CO2-based VAPEX process can be more cost effective and environmentally friendly than the conventional VAPEX process. Introduction With the decline of conventional oil reserves, a major thrust of oil producers throughout the world is on the exploitation of heavy oil and bitumen reserves. The magnitude of these resources worldwide is about six trillion barrels of oil-in-place; six times total conventional reserves(1), and is likely to be the future source of energy. The majority of these resources are located in Venezuela, Canada and the United States(2). In most cases, conventional recovery methods cannot be implemented in heavy oil and bitumen reservoirs due to the high viscosity(3) of the oil. The high viscosity rules out primary production in many reservoirs, and even in lower viscosity reservoirs, the primary recovery is less than 10% of the original oil-in-place (OOIP)(4, 5). The Steam-Assisted Gravity Drainage (SAGD)(6, 7) process has gained tremendous popularity in the industry for its usefulness in producing high viscosity heavy oil and bitumen. In this process, the heat is injected into the reservoir by injecting steam through a horizontal well; steam condenses at the boundary of a growing steam saturated zone and heats the oil. Consequently, the viscosity is lowered and the hot oil drains down under the influence of gravity into another horizontal well located near the bottom of the formation. Even though thermal methods are successful in exploiting these resources, they often suffer from low energy efficiency due partly to heat losses to the cap and base rock.
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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 | 0.002 | 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 it