Conference proceeding
Photogrammetry informed fracture network characteristics in a sandstone aquifer for 3-dimensional discrete fracture network simulation
American Geophysical Union Fall Meeting, Vol.2018
American Geophysical Union 2018 fall meeting
12/2018
Abstract
A growing body of scientific literature has demonstrated that preferential flow through discrete fractures has a profound impact on the supply capacity and the transport of contaminants through sandstone aquifers that are commonly treated as porous media. Despite the importance of fracture flow in these systems, very few studies provide rigorous evaluation of the geometrical and statistical properties of fracture networks. Time and cost restraints typically limit most studies to datasets collected from open vertical boreholes, which are poorly suited for characterization of 3-D fracture networks. In this study, close range terrestrial photogrammetry (CRTP) and traditional fracture mapping techniques were used to survey 732 fractures at six outcrops of the Wonewoc Sandstone in western Wisconsin. These measurements were combined with core, optical and acoustic televiewer data from 20 boreholes at a contaminated site (with the same stratigraphic units but 225 km away) to develop a 3-D discrete fracture network (DFN) model of the Wonewoc Sandstone. A thorough assessment of CRTP measurements confirms that the method is capable of accurately recording 3-D fracture information (position, orientation, length) necessary for describing fracture network geometries. CRTP proved particularly useful for measuring trace lengths and identifying the orientation and spacing of vertical fracture sets that are poorly delineated by vertical boreholes. Ultimately, CRTP provided most data necessary for DFN simulation, except for fracture aperture and permeability, which were instead estimated using hydraulic data collected from packer testing in boreholes at the contaminated site. Using the DFN model, aquifer heterogeneity and anisotropy could be evaluated by statistically describing variability in hydraulic conductivity resulting from the simulated fracture network. The simulated DFN can also be used to assess the impact of matrix diffusion on solute transport, or to provide fracture porosity for estimating linear groundwater velocity in equivalent porous media models. Fundamentally, the study demonstrated the utility of using CRTP to rapidly collect accurate measurements of fracture orientation and position from otherwise inaccessible outcrops, requiring only standard survey equipment and a digital camera.
Details
- Title: Subtitle
- Photogrammetry informed fracture network characteristics in a sandstone aquifer for 3-dimensional discrete fracture network simulation
- Creators
- Christopher Aaron Morgan - University of GuelphJessica R MeyerAnthony RunkelEmmanuelle ArnaudBeth L Parker
- Resource Type
- Conference proceeding
- Publication Details
- American Geophysical Union Fall Meeting, Vol.2018
- Conference
- American Geophysical Union 2018 fall meeting
- Publisher
- American Geophysical Union
- Alternative title
- AGU 2018 fall meeting
- Language
- English
- Date published
- 12/2018
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240786602771
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