Bibliographic record
Abstract
Hydraulic fracturing is a process that is used to release and extract natural \ngas from the pores of shale rocks. The process involves drilling vertical and \nhorizontal wells through shale formation beds. After which, a mixture of \nfluid and sand is pumped into the rock formation through the horizontal well, \npressurizing the shale around the well, causing multiple permeable cracks to \nform. Studying hydraulic fracturing helps Oil and Gas companies to improve \nthe efficiency and productivity of this process. \nBecause the hydraulic fracturing process takes place hundreds of meters \nbelow the ground’s surface, its behavior is difficult to physically assessed. \nComputer modeling is an efficient and economical way to study and \nanalyze the behavior of the process. Finite element modeling, as a \nnumerical tool, can be used to solve such non-linear fracture problems. \nIn this thesis, finite element modeling is used to study two-dimensional, \nsingle, and multiple crack propagation problems that occur during fluid injection. \nThe single fracture problem is compared with a well known analytic \nmodel (KGD model) in order to verify the efficiency of the numerical finite element \nmodel. The effects that rock and fluid material properties have on the \nfracture propagation, crack width, and fluid pressure is studied. As a result, \nthe finite element numerical model is found to be in good agreement with the \nKGD analytical solution. Moreover, the analysis revealed that small changes \nin the material properties (e.g., rock elasticity modulus, permeability, and \nfluid viscosity) have significant effects on fracture propagation. \nMultiple crack problems, using three parallel cracks, are also investigated. \nThe effects of the fracture spacing and type of fluid control (flow rate or pressure \ncontrol) are studied. Stress shadowing (induced stresses from the adjacent \nfracture) between multiple fractures is evaluated. For the edge cracks, \nit is found that as the fracture spacing decreases, the crack length increases. \nWhile, for the middle crack, as the fracture spacing decreases, the crack \nlength decreases. It is shown that fluid flow controlled injection leads to stable crack injection, while pressure control injection leads to unstable \ncrack propagation. \nIn summary, this thesis finds that an optimal spacing for three crack \nhydraulic fracturing is between equal fracture spacing and two-third the distance \nbetween the middle and any of the edge cracks. It is recommended \nthat future engineers extend this research to simulate a three-dimensional \nproblem with randomly oriented fractures.
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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 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".