Numerical Simulation of In Situ Combustion Experiments Operated under Low Temperature Conditions
Bibliographic record
Abstract
Abstract During In-Situ Combustion (ISC) processes, different chemical reactions occur depending on the temperature level. In heavy oils and bitumens Low Temperature Oxidation (LTO) reactions dominate below 300 °C, increasing the density and viscosity and producing coke which could prevent the success of ISC. Above 350 °C, combustion reactions dominate, known as High Temperature Oxidation (HTO), producing carbon oxides and water. Numerical models tend to include only thermal cracking and HTO reactions, as LTO reactions are not well understood. In the present work, ISC experiments operated under LTO were simulated, using Saturates, Aromatics, Resins and Asphaltenes (SARA) fractions to characterize the Athabasca bitumen. Concentration profiles and coke deposition for individual temperatures were matched for isothermal experiments from 60 °C to 150 °C. Based on these results, Ramped Temperature Oxidation (RTO) experiments were then modelled, incorporating the heat of reaction at LTO. Different reaction models were studied to match temperature profiles along the reactor, oxygen consumption, coke formation and fluids production. This research will greatly increase the understanding of LTO reactions occurring in Athabasca bitumen during ISC and contribute to the creation of a reliable numerical model that predicts ISC performance under ideal (HTO) and, importantly, non-ideal (LTO) temperature conditions. Introduction In Situ Combustion (ISC) is a promising but complex oil recovery process in which thermal energy is generated inside the reservoir due to combustion reactions between the heaviest fractions of the oil and an injected oxygen containing gas. For heavy oils and bitumens, ignition temperatures above 350 °C are required to promote the combustion reactions (HTO). At lower temperatures other types of reactions predominate, involving the addition of oxygen to the bitumen, producing heavier oxidized compounds. The low temperature oxidation (LTO) reactions are detrimental to oil production hence ISC processes are designed to operate under the high temperature combustion regime (HTO). However, LTO reactions occur if the air flux becomes too low to sustain the combustion reactions, leading to lower than estimated production yields. It has been proven in laboratory experiments that oil recovery is considerably reduced when Low Temperature Oxidation reactions occur to some extent, compromising the success of the ISC. Even though the adverse effect that LTO reactions could have on ISC processes has been shown by different authors [1–3] most numerical simulations of ISC still exclude them [4–6]. Generally, numerical simulations rely only on the high temperature reactions consisting of deposition of coke due to thermal cracking and coke combustion, which leads to unrealistic predictions. The complexity of LTO reactions and the lack of a thorough understanding of their effect on ISC is the main reason for their exclusion in numerical models. Despite all the efforts of studying the kinetics of LTO, there is still a lack of comprehensive kinetic models able to represent the main effect of these reactions on ISC processes. Belgrave et al.[7] were one of the first to include LTO reactions in ISC numerical models.
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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 | 0.000 | 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 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".