Numerical Modelling of Geomechanical Response of Sandy-Shale Formation in Oil Sands Reservoir During Steam Injection
Bibliographic record
Abstract
Abstract In this study, we conducted numerical simulations of steam injection into a horizontal well. A sandy-shale layer with thickness of 1 metre is located 2 metre above a horizontal injection well. The numerical simulations intend to study the variations of the stress state and the permeability in the sandy-shale layer during steam injection, and to provide useful effective stress paths for laboratory experiments to follow when testing material properties of the sandy-shale. A self-developed coupled geomechanics and thermal multi-phase flow simulator was employed to conduct the simulation cases. A strain-induced permeability model was used to describe the anisotropic permeability change of the sandy-shale caused by steam injection. The simulation results demonstrate that the permeability of 5 and 50 md for the sandy-shale in two simulation cases is sufficient to allow pore pressure dissipation to occur, therefore, preventing tensile or shear failure of sandy-shale as a result of high thermal-induced pore pressure. The stress paths within the sandy-shale are approaching the failure envelope as steam injection goes on indicating simultaneous influence of the temperature and the pore pressure on the stress state change. Introduction Sandy-shale formations of several metres in thickness frequently exist in oil sands deposit. Their material properties, sedimentary characteristics and distribution in a steam-assisted gravity drainage (SAGD) reservoir are important factors that determine SAGD performance and strategies of positioning horizontal well-pairs. It has been confirmed that sandy-shale formations are usually very sandy and discontinuous; therefore, they are expected to be permeable to varying degrees during SAGD operations. This is completely different from the interbedded shales that have extremely low permeability and can be considered as impermeable. Analysis of stress state change and anisotropic permeability variation in the sandy-shale requires conducting coupled simulation of geomechanics and thermal reservoir flow. Numerical modelling of the coupled processes is historically carried out in the areas of geomechanics modelling and the reservoir simulation. Gutierrez and Lewis(1) extend Biot's theory to multi-phase fluid flow in deformable porous media. Based on their formulation, they conclude that the coupling between the geomechanics and the multi-phase flow occurs simultaneously. Thus, fully coupled system equations of deformations, multi-phase flow and heat transfer should be solved simultaneously.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".