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The AAPG/Datapages Combined Publications Database

Environmental Geosciences (DEG)

Abstract

Environmental Geosciences, V. 11, No. 3 (September 2004), P. 129-142.

Copyright copy2004. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

DOI: 10.1306/eg.02040403029

High-resolution seismic detection of shallow natural gas beneath Hutchinson, Kansas

Susan E. Nissen,1 W. Lynn Watney,2 Jianghai Xia3

1Kansas Geological Survey, 1930 Constant Avenue, Campus West, The University of Kansas, Lawrence, Kansas, 66047; [email protected]
2Kansas Geological Survey, 1930 Constant Avenue, Campus West, The University of Kansas, Lawrence, Kansas, 66047
3Kansas Geological Survey, 1930 Constant Avenue, Campus West, The University of Kansas, Lawrence, Kansas, 66047

AUTHORS

Susan E. Nissen is a geophysicist at the Kansas Geological Survey (KGS). She received a B.S. degree (1983) from the University of Delaware and a Ph.D. (1992) from Columbia University. Prior to joining the KGS in 2000, she spent 8 years as a research scientist with Amoco. Her main interest is integrating 3-D seismic attributes with well data to improve geological interpretations.

W. Lynn Watney is a senior scientist at Kansas Geological Survey and executive director at the University of Kansas Energy Research Center. He joined KGS in 1976 and is an alumnus of Chevron. He received a Ph.D. (1985) from the University of Kansas and B.S. (1970) and M.S. (1972) degrees from Iowa State University. His current interests are late Paleozoic stratigraphy, multidisciplinary reservoir modeling and play characterization, and developing collaborative web-based, integrated petroleum reservoir modeling tools.

Jianghai Xia received a Ph.D. (1992) in geology with emphasis in geophysics from the University of Kansas. He is an associate scientist at the Kansas Geological Survey. His main research interest is near-surface material characterization by integrated geophysical tools, including shallow seismic reflection and refraction, surface wave technique, ground-penetrating radar, electromagnetics, and potential fields.

ACKNOWLEDGMENTS

The authors thank the following individuals and corporations for their contributions to this project: Charles Mountford, ONEOK, for logistical support; Rick Miller, Dave Laflen, Chadwick Gratton, and Joe Anderson for seismic data acquisition; Joe Anderson for well logging; Rod Pellegrini and Mike Magnuson for sample preparation; Allyson Anderson for data compilation; and Seismic Micro-Technology, Inc. and GeoPLUS Corporation for access to software.

ABSTRACT

Two high-resolution seismic reflection surveys were conducted to identify shallow natural gas that had caused explosions in Hutchinson, Kansas, in January 2001. Gas presence is associated with both a bright spot and a dim-out on the seismic reflection profiles. Core and log data from wells drilled to vent the gas indicate that the gas-bearing interval corresponds to thin dolomite layers, which have higher P-wave velocities than the surrounding shales. Gas in fractures can reduce the Previous HitvelocityNext Hit of the dolomite interval to that of the shales (or lower). Depending on the magnitude of the Previous HitvelocityNext Hit change, either a dim-out or bright spot is produced. Sonic logs from gas-bearing vent wells, recorded after venting of gas, show no anomalous Previous HitvelocityTop, indicating that as gas dissipates, any associated seismic anomaly will be reduced.

Lateral variations in the seismic properties of the gas-bearing interval and adjacent strata (namely, variations in dolomite and shale content) also have a significant effect on the seismic signature of the interval, mimicking the effect of a small amount of gas. Only where the gas zone is relatively thick (2ndash3 m; 7ndash10 ft), creating a high-amplitude negative seismic reflection, is the seismic signature diagnostic of gas. Therefore, whereas the dim-outs observed on the seismic reflection profiles may be the result of gas presence, they are equally well explained by lateral variations in lithology. Dim-outs should not be used in the Hutchinson area as an indicator of gas. The observed bright spot, however, is most likely a unique gas response.

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