Mineralogy and Scaling Relationships in Shale During Acidification: Models and Experiments
Abstract/Contents
- Abstract
- Acidic reactive flow and the dissolution of carbonate minerals in porous media is important in many subsurface activities, such as hydraulic fracturing, carbon geological sequestration and wastewater disposal. The mineralogy of the rock and their evolution in pore structure during acidization are critical factors for predicting subsurface flows, such as leakage, injectability and fluid production. In this work, we studied the interplay between flow, reaction and boundary motion of real rock samples incorporated in microfluidic chips. In particular, we examined how the mineralogy of shale, a fine-grained sedimentary rock, controlled the evolution of its interface, surface area and porosity during acidification, including the scaling between such quantities. The two shale samples used in this study were Marcellus (MCL) and Wolfcamp 2H5 (WFC). The MCL sample is a homogeneously carbonate-rich shale, while the WFC sample is characterized by its grain-like distributions of carbonate. Each shale sample was polished, fractured and positioned inside a fabricated microfluidic chip. Once the system reached steady-state flow conditions, 1% hydrochloric acid was injected into the inlet of the shale embedded microfluidic chip at a flow rate of 1000μL/hour for 3 minutes. Preferential dissolution of carbonate over inert minerals led to the creation of channels and cavities and an increased fracture roughness in the WFC sample. Meanwhile, uniform dissolution into the matrix had smoothened the surface of the MCL sample. Video segmentation and image analyses were performed to quantify the changes in porosity and interfacial length. The results show that the evolution of surface geometry depended strongly on the carbonate component of the shale and their spatial distributions, with a positive correlation between the porosity and interfacial length in the WFC sample and a negative correlation in the MCL sample. In addition, a novel approach was devised to model the observed correlation between mineralogy and changes in surface geometry from acidization mathematically. The devised model captured the scale of the changes in porosity and interfacial length effectively. However, a fitting parameter was necessary to shift the intercept of the model results to align with the experimental results. The evolution of shale interface and porosity depends in a complex way on the carbonate minerals and their spatial distribution. The scale of these changes due to the mineral composition and patterning can be captured through a simplified model.
Description
| Type of resource | text |
|---|---|
| Date created | May 2021 |
Creators/Contributors
| Author | Sodwatana, Mo |
|---|---|
| Primary advisor | Battiato, Ilenia |
| Degree granting institution | Stanford University, Department of Energy Resources Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Subject | Department of Energy Resources Engineering |
| Subject | Stanford University |
| Subject | acidic reactive flow |
| Subject | shale-embedded microfluidic |
| Genre | Thesis |
Bibliographic information
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- User agrees that, where applicable, content will not be used to identify or to otherwise infringe the privacy or confidentiality rights of individuals. Content distributed via the Stanford Digital Repository may be subject to additional license and use restrictions applied by the depositor.
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Preferred citation
- Preferred Citation
- Sodwatana, Mo. (2021). Mineralogy and Scaling Relationships in Shale During Acidification: Models and Experiments. Stanford Digital Repository. Available at: https://purl.stanford.edu/gw386wv0419
Collection
Master's Theses, Doerr School of Sustainability
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- Contact
- jarupas@stanford.edu
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