Numerical study of thermal-hydraulic-mechanical behavior of fractured geothermal reservoirs
Bibliographic record
Abstract
This work aims to develop powerful numerical tools to study the thermal-hydraulicmechanical (THM) behavior of fractured geothermal reservoirs.It contains three parts: a massively parallel fully coupled THM simulator, a semi-analytical correlation to capture the thermal induced fracture aperture change and the multistage preconditioning used for THM simulation.A massively-parallel, fully-coupled THM simulator, THM-EGS, has been developed and verified.The simulator is written in Fortran 03 and the governing equations are solved using Integral Finite Difference Method (IFD).Mechanical deformation effects are captured by solving a mean stress equation, derived from the equations governing deformation of porous media.This equation is computationally efficient and accurate enough for reservoir flow applications.The simulator has an efficient parallel computation scheme using MPI for communication between processes.A novel correlation of the thermal-induced normal change of fracture aperture has been derived.The new correlation is based on the solution of the governing displacement equations.Compared to the existing empirical correlations, the new correlation can better describe the physical processes.The new correlation can also be applied to elastic-plastic fractures.We have implemented this correlation in THM-EGS.The correlation has been used to study the permeability enhancement effect of a hydraulically connected well pair.The results are that the permeability will be enhanced by as large as 2 orders of magnitude.The results of this study have the potential to guide the operations of geothermal reservoirs.iv We will also investigate multi-stage preconditioning in THM simulation.We will implement a Constraint Pressure Residual (CPR) type multistage preconditioner into the linear solver of THM-EGS.In the multistage preconditioner, the fluid, energy and mechanical equation are preconditioned with different strategies based on their own unique feature.The multistage preconditioner has been tested on both homogeneous and heterogeneous problems.It has greatly improved the numerical performance of the linear solver, especially for highly heterogeneous problems.
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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 | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".