Modeling the Displacement of Gases in Coal Beds
Abstract/Contents
- Abstract
- Enhanced Coal Bed Methane (ECBM) recovery can be done by injecting gases to displace methane that is initially adsorbed on the coal surface. The chromatographic partitioning of each gas occurs due to the difference in sorption affinity. To model this process accurately, sorption characteristics including hysteresis need to be known because the flow involves not only adsorption, but also desorption. A nonlinear convection-dispersion equation for each component for one-dimensional flow can be written, and a numerical simulator can then be used to solve the system of equations. In this report, a detailed formulation for the ECBM simulator is presented. The simulator is then used to perform sensitivity studies of factors that affect the displacement behavior. Adjusting porosity, coal density, and sorption affinity cause significant changes to the volume loss of adsorbing gases, and the volume gain from desorbing gases. These three parameters, therefore, strongly affect volume change on mixing, and have the largest effects on flow performance. After that, simulations for the binary and ternary systems are investigated, and the results are compared with results of slimtube experiments. A systematic approach for tuning up the parameters is described. Analytical solutions are used to help matching, and the parameters are adjusted based on the knowledge from sensitivity studies. The simulator is applied for acid gas injection problems in which the system has up to 5 components. A solution for CH4, CO2, N2, H2S with other gases system is presented as a series of shocks and rarefactions. Their separations depend on how strongly each component adsorbs. Gases that have stronger sorption affinity move slower, and vice versa. H2S which adsorbs stronger than CO2 can then be stored in coal along with CO2. The results from this study also establish the basic understanding of multicomponent gas displacement in coal beds.
Description
| Type of resource | text |
|---|---|
| Date created | June 2009 |
Creators/Contributors
| Author | Boontaeng, Thanapong |
|---|---|
| Primary advisor | Orr Jr., Franklin M. |
| Degree granting institution | Stanford University, Department of Energy Resources Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Genre | Thesis |
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Preferred citation
- Preferred Citation
- Boontaeng, Thanapong. (2009). Modeling the Displacement of Gases in Coal Beds. Stanford Digital Repository. Available at: https://purl.stanford.edu/vb831hv7442
Collection
Master's Theses, Doerr School of Sustainability
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