Investigation of Shale Gas at Nanoscale Using Scan Electron Microscopy, Transmission Electron Microscopy and Atomic Force Microscopy, and Up-scaling to a Petrophysical Model for Water Saturation Evaluation in Shales
Bibliographic record
Abstract
Abstract Due to quick development in horizontal drilling and fracturing technologies, shale gas, formerly considered very difficult if not impossible to recover, has become one of the hottest energy topics. As a significant number of studies focus on fracture stimulation, drilling and completion optimization, only a limited number of studies have been carried out aiming at the investigation of shale structure at nanometer scale due to limited access to scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM), and also due to less experience using these instruments in studies of formation rocks. SEM and TEM are all capable of revealing nano-scale structures of rock samples. AFM also offers some possibilities. In order to obtain images of high quality and ultra-high magnification, sample preparation is the initial and probably most important step in the whole imaging process. Images from low and ultra low permeability formations in the Western Canada Sedimentary Basin are compared with images from other low and ultra low permeability formations reported in the literature. As powerful as these nanoscale capable microscopes are, they all have limitations due to the high instrument cost, limited access and time consuming imaging process. As a result it is difficult and impractical to obtain statistical significant data. To make these instruments of practical value to geoscientists and petroleum engineers, methods and models need to be developed to build a bridge from detailed nanoscale structures to typical lab/field measurements and practical geoscience and engineering-scale applications. In this paper, we propose the concept of a multiple porosity model for evaluation of shale formation based on our observations of the nanopore structure of shales. This includes a model for determining the porosity exponent m in shales and water saturation evaluation. Water saturation curves based on this model are plotted on Pickett Plots for both tight gas and shale formations. Continuous studies in this area are needed to further explore shale structure in fine detail in order to understand the role of nanopores on shale gas production.
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How this classification was reachedexpand
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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".