Numerical Simulation of Huff-And-Puff Gas Injection in Shale Reservoirs Using an Integrated Model of Geomechanics and Multiporosity Fluid Flow
Bibliographic record
Abstract
Abstract Improving oil recovery is one of the main challenges of shale play exploitation, and huff-and-puff gas injection has established itself as one of the most important techniques for the industry and academia. Therefore, understanding the physics of huff-and-puff gas injection in shale reservoirs is significantly of interest. However, the multiporosity, multitransport mechanism and stress-dependent nature of shale reservoirs make this a very complex task. This paper aims at investigating huff-and-puff gas injection, considering multiple storage and transport mechanisms present in shale reservoirs as well as the effect of rock deformation on them. This is attained by using a new in-house 3D integrated numerical simulator of fluid flow and geomechanics. The simulator incorporates a quintuple porosity formulation (and gas dissolved in the solid kerogen), several transport mechanisms (Darcy flow, slip flow and Knudsen diffusion), and the effect of rock deformation on these storage systems and transport phenomena through an iterative coupling with the rock mechanics model. The model accounts for hysteresis in rock properties during the huff-and-puff cycles. Constitutive laws for isotropic and vertical transverse isotropic (VTI) materials are implemented and simulations of primary recovery and huff-and-puff scenarios are carried out for both rock behaviors. Simulation results illustrate the effect of the huff-and-puff cycles on the stresses in hydraulic fractures, natural fractures and the shale matrix. The behavior of adsorbed porosity, organic porosity and sorption-dependent permeability is shown and analyzed. The changes in hydraulic fracture permeability due to variation in stresses are presented along with the effect of hysteresis, revealing multiple rebound curves generated during the huff-and-puff cycles. Comparison of results between the isotropic and VTI models displays moderately different results for the cases analyzed in this work. Simulation results also corroborate the importance of good hydraulic fracture properties and adequate gas injection rates in the performance of huff-and-puff injection projects in shale reservoirs. Simulation of huff-and-puff gas injection in shale reservoirs using a 3D integrated model that incorporates a quintuple porosity formulation, multiple transport mechanisms and rock mechanics (including hysteresis effects) has not been published in the literature. This is a step forward in the modeling and understanding of huff-and-puff injection processes in shale reservoirs.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".