Determination of Fracture Aperture A Multi-Tracer Approach
Abstract/Contents
- Abstract
- This work shows that fracture aperture can be calculated from tracer tests involving two tracers with different affinities for adsorption onto the rock. In 1983 Jensen proved that fissure aperture can be determined when adsorptive effects are neglected. Adsorption introduces an additional unknown, the retardation factor, into the governing equations. When two tracers are injected, the number of available equations expands to match the number of unknowns.This report also presents equations based on the matrix diffusion model which allow estimation of fracture aperture through visual examination of tracer tests. Tracer data from tests in the Wairakei geothermal field in New Zealand were analyzed by the visual method. The results were compared to computations using nonlinear regression. The two analyses differed randomly with an average variation of f 40%.Experiments were performed in which three tracers, sodium chloride, ethyl alcohol and isopropyl alcohol, were flowed through a fractured core. The effective diffusivity of the rock was determined by measuring the salt concentration at the inlet and at two points along the fracture. The analysis of the data made use of an analytical solution to the matrix diffusion model in which the inlet boundary condition is expressed in terms of a complementary error function. Although the effective diffusivity was estimated, the amount of adsorption which occurred during the flow tests could not be determined quantitatively. The sampling frequency was too low to provide good resolution of the breakthrough curve. Interestingly, the differences in molecular diffusion of the tracers seemed to dominate over adsorption effects.
Description
| Type of resource | text |
|---|---|
| Date created | June 1988 |
Creators/Contributors
| Author | Fox, Charles E. |
|---|---|
| Primary advisor | Horne, Roland N. |
| Degree granting institution | Stanford University, Department of Petroleum Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Genre | Thesis |
Bibliographic information
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Preferred citation
- Preferred Citation
- Fox, Charles E. (1988). Determination of Fracture Aperture A Multi-Tracer Approach. Stanford Digital Repository. Available at: https://purl.stanford.edu/tp179ty6460
Collection
Master's Theses, Doerr School of Sustainability
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