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Post by Admin on Oct 19, 2017 7:13:05 GMT -5
Overview The USGS Scenario Evaluator for Electrical Resistivity (SEER) is a quick and simple Excel-based decision support tool practitioners can use to assess the likely outcome of using two-dimensional (2D) electrical resistivity imaging for site characterization and remediation monitoring. SEER features a graphical user interface (GUI) that allows users to manipulate a resistivity model and instantly view how that model would likely be interpreted by an electrical resistivity imaging survey. The SEER tool is intended for use by practitioners who wish to determine the value of including electrical resistivity imaging to achieve project goals, and is designed to have broad utility in industry, teaching, and research. For more information go to: water.usgs.gov/ogw/bgas/seer/ |
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Post by Frozen Cowboy on Oct 30, 2017 22:50:57 GMT -5
Could one use SEER to determine if ER could used to detect a hydrocarbon plume in permafrost?
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Post by Lee Slater on Oct 31, 2017 10:37:44 GMT -5
SEER can be used to model any hypothetical subsurface scenario. In this case, you would need to provide estimates of the resistivity of the native permafrost and the resistivity of the hydrocarbon plume. You would need to estimate the (2D) dimensions of the plume [remembering that SEER assumes the cross-sectional structure extends infinitely in the direction orthogonal to the plume]. Good estimates of the resistivity of permafrost are available in the literature. The resistivity of a hydrocarbon plume (in permafrost) would be subject to substantial guesswork.
Note: I am having a problem conceptualizing a hydrocarbon plume in permafrost. Perhaps the model is a hydrocarbon plume in the active layer in a part of the world where permafrost exists or is melting?
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Post by Frozen Cowboy on Nov 1, 2017 12:46:43 GMT -5
Thanks very much for the information on modeling a hydrocarbon plume in permafrost. Yes, there are permafrost areas where a hydrocarbon plume has been found.
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emeka
New Member
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Post by emeka on Jan 10, 2018 4:04:35 GMT -5
What is the success rate of the Scenario Evaluator for Electrical Resistivity Survey Pre-modeling Tool and what optimisation tool is used?
How do we also deal with the issue of uncertainty?
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Post by judyasuser on Jan 10, 2018 8:19:19 GMT -5
Rather than thinking of SEER as having a success rate, it is a pre-modeling tool and the overall results would be as reliable as the conceptual site model input and electrical resistivity survey parameters chosen. We hope that by using available site data for planning, implementation of an electrical resistivity survey will more likely be successful than otherwise. As far as optimization, the SEER download includes full numerical modeling results for the scenarios you can choose in the excel worksheet (for example, the electrode spacing, noise levels, survey configuration). These full numerical modeling results were performed using R2 (Binley, Lancaster UK, www.es.lancs.ac.uk/people/amb/Freeware/R2/R2.htm) which optimizes the trade off between data misfit and model structure and solves for the smoothest model that can fit the data. This means that the actual subsurface model has at least as much resistivity structure as shown, which is a conservative way to translate these images. Your question regarding uncertainty is a good one and very important! I suggest you try several conceptual site models, by this I mean manually edit the starting resistivity structure. Then for a given electrode spacing, survey configuration and noise level, see how the results compare. It is quick and easy in SEER to run as many conceptual site models as you would like to test and the models can then be used to plan your field survey. |
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