Coke formation during thermal cracking of a heavy crude oil
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
A pseudo-mechanism for the production of coke during the thermal cracking of a Colombian heavy crude oil was proposed based on thermal cracking experiments carried out at TGA and at horizontal tube furnace at atmospheric conditions. In-situ combustion (ISC) is a thermal method that improves the recovery of heavy crude oils and involves complex phenomena such as heat and mass transfers, low-temperature oxidation of the liquid phase (LTO), and cracking reactions that yield coke, a carbonaceous residue that, after high-temperature oxidation (HTO) produces the heat that reduces the oil viscosity increasing the recovery factor. During cracking experiments, Ottawa sand was mixed with crude oil, or with a mixture of maltenes and asphaltenes extracted from that oil, and placed under nitrogen atmosphere and heated at 2oC/min up to di_erent reaction temperatures (300oC, 350oC, 400oC and 450oC) at atmospheric pressure conditions. Even tough atmospheric pressure conditions is not a realistic condition as oil reservoirs operate above atmospheric pressure, this study as part of a bigger project to study ISC it was the _rst that develop a setup and a methodolody able to study ISC reactions. After the _rst approximation that this study made, further work will be carried out to study ISC process at more realistic conditions. This study found that the main cracking products were volatiles that could be condensables and non-condensables and a solid residue. Proximate, elemental, GC-MS and SIMDIS analysis were performed to establish the composition of the cracking products, and to determine the advance in the cracking reactions. During cracking experiments each oil fraction yielded lower- and heavier-molecular weight products. e.g. maltenes yielded gas (mainly composed by methane CH4), distillables (a condensable fraction with maximum 18 carbons), low-molecular-weight maltenes (LMWM, a condensable fraction with maximum 28 carbons, that results from the cracking of maltenes and asphaltenes), and asphaltenes. Whereas asphaltenes leaded to coke formation and to LMWM and gases. The proposed pseudo-mechanism considers the formation of lower- and heavier molecules, separates the evaporation process from the thermal cracking, and proposed new pseudocomponents such as Maltenes* that represents the maltenes fraction after the evaporation process and the one available for thermal cracking, and LMWM that is an upgraded cracking product of the cracking of maltenes* and asphaltenes that had a yield of 0.28 g/gtot. Furthermore, the proposed pseudo-mechanism proposes kinetic parameters for the thermal cracking of a Colombian heavy crude oil under in-situ combustion conditions at atmospheric pressure. The kinetic parameter were optimized by minimizing the sum of square error (SSE) between the experimental and calculated yields. A good coe_cient of determination was obtained, (R2=0; 97), using _rst order kinetic parameters. The physical interpretation of the value of kinetic parameters is complicated given the rather empirical approach used to find the kinetic parameters, it is important to note that most parameters in particular activation energies have values typical for chemical-controlled process, exceptions to this are the activation energies 26.4 and 9760 kJ/mol that are too low and too high that involve the decomposition of asphaltenes and are accompained by very low pre-exponential factor.Future work may focus on reducing the empirical nature of this mechanism.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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