| Abstract: | The results of a limited field trial confirm the usefulness of borehole-to-surface electromagnetic (EM) measurements for monitoring fluid extraction. A vertical EM profiling experiment was done at the University of California Richmond Field Station, where we simulated a brine spill plume by creating a saline water injection zone at a depth of 30 m. The data acquisition mode was analogous to the reverse vertical seismic profiling (VSP) configuration used for seismic measurements in that the EM transmitter traversed the PVC-cased borehole used for fluid injection and extraction while the receivers were deployed on the surface. The EM measurements were made at 9.6 kHz with an accuracy of 1% in signal amplitude and 1??in signal phase. Observations were taken at 5-m intervals along two intersecting profiles that were centered on the injection well and extended for 60 m on either side of it. The presence of the injected salt water, at the expected 30 m depth, was indicated clearly by differences between the pre-extraction and postextraction data. A limited amount of numerical modeling showed that the experimental data were consistent with the presence of two superposed saline plumes. The uppermost of these, located at 26 m depth, was 2 m thick and had an area of 30 m2. The lower plume, located at 30 m, is the major cause of the observed anomally, as it has an areal extent of 120 m2 and a thickness of 3 m. Surprisingly, the measurements were very sensitive to the presence of cultural surficial conductivity anomalies. These spurious effect were reduced by spatial filtering of the data prior to interpretation.The results of a limited field trial confirm the usefulness of borehole-to-surface electromagnetic (EM) measurements for monitoring fluid extraction. A brine spill plume is simulated by creating a saline water injection zone at a depth of 30 m. The data acquisition mode was analogous to the reverse vertical seismic profiling (VSP) configuration used for seismic measurements in that the EM transmitter traversed the polyvinyl chloride-cased borehole used for fluid injection and extraction while the receivers were deployed on the surface. Observations were taken at 5-m intervals along two intersecting profiles that were centered on the injection well and extended for 60 m on either side of it. |
| Genre: | Article |
| ProdID: | 70020654 |
| Citation Author: | Tseng, H. -W.; Becker, A.; Wilt, M. J.; Deszcz-Pan, M. |
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| Citation End Page: | 1572 |
| Citation Issue: | 5 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geophysics |
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| Citation Number Of Pages: | 8 |
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| Citation Publisher: | Soc of Exploration Geophysicists |
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| Citation Search Results Text: | A borehole-to-surface electromagnetic survey; 1998; Article; Journal; Geophysics; Tseng, H. -W.; Becker, A.; Wilt, M. J.; Deszcz-Pan, M. |
| Citation Start Page: | 1565 |
| Citation Volume: | 63 |
| Citation Year: | 1998 |
| Type: | citation/reference |
| Text: | A borehole-to-surface electromagnetic survey; 1998; Article; Journal; Geophysics; Tseng, H. -W.; Becker, A.; Wilt, M. J.; Deszcz-Pan, M. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Thu, 1 Jan 1998 00:00 -0600 |
| Publisher: | Soc of Exploration Geophysicists |
