ISGS - January 2005 Activity Highlights

Seismic Profiles Reveal Gas Path Ways at Storage Field

3-Dimensional map image of the storage field

Combined P-wave and S-wave seismic profiles over a gas storage facility in north-central Illinois are being used to locate shallow gas in storage facility. Although several faults had been documented in the Mt. Simon Formation during development of the storage facility, they were not thought to extend to the shallower bedrock. Our detailed reflection profiles showed that the faults do extend within the bedrock to the upper layers and provide the migration pathway for gas to move upwards from the storage facility. Seismic S-waves are not sensitive to the presence of gas so they were used to image the stratigraphy. Even with our very small S-wave source (a 1-kg hammer horizontally striking a weighted steel plate), the bedrock layers could be imaged down to 400 to 500 feet. We attribute this success to the use of innovative S-wave reflection data acquisition and processing techniques developed at the ISGS. Seismic P-waves are extremely sensitive to the presence of even a few percent (by volume) of gas in pore space, and we used our P-wave land-streamer technology to detect and map the gas zones. By combining the results of the two methods, both the gas zones and the gas migration paths can be clearly mapped in three dimensions. This study has been conducted in collaboration with Illinois State University and will be the basis of a thesis for a master’s degree candidate in geology. The techniques used here should be broadly applicable for mapping the movement of gas in the shallow Earth. (Contact: T. Larson)

3-D perspective map of Colchester coal depth

Experts at the Illinois and Indiana Geological Surveys have compiled GIS maps showing the areal distributions of coal quality parameters for the seven major coal seams across the entire Illinois Basin. Data layers for the ash, sulfur, and moisture contents were created for all seven seams. Data were sufficient to map the calorific contents (BTU contents determined by different methods) and reflectance values for the widespread and thick Springfield and Herrin seams. The coal quality data sets comprise 30-plus GIS layers. The new coal quality data layers will be combined with available data on coal resources distribution. The combined data will be used in newly created models that will use ArcGIS methods to estimate coal bed methane resources. The new data layers should be useful for estimating the potential for the coals to adsorb and sequester carbon dioxide. (Contacts: I. Demir, C. Korose and D. Morse)

      • Through an hour-long telephone conversation, the ISGS helped the owners of property in Boone County understand the steps involved in evaluating the potential presence of limestone resources under their property and the geological, economic, and other factors that should be considered in determining the value of the stone and the value of the property. The property owners were advised to engage a private consultant to assist them in accurately evaluating the important factors related to the particulars of their acreage. (Contact: S. Bhagwat)
      • An engineering firm engaged in designing a tunnel under the Des Plaines River near the lock and dam at Joliet was given information about the depth to bedrock, the nature of the rocks they would expect to find in the area, and the material properties of the rocks that would affect tunnel construction. (Contacts: P. Weibel; R. Bauer)
      • A well driller seeking a 100+ gpm water source for a waterfowl hunting club south of Marion received advice on the characteristics of the surficial and bedrock materials in the area and the aquifers most likely to be found there that could supply the amount of water needed. (Contact: R. Rice)
      • A consultant hired by a company planning to build an ethanol plant near Lincoln requested information about the best way to locate abandoned underground coal mine workings in the area. He was justifiably concerned about the accuracy of mine maps he had obtained that had been constructed in the period from the 1880s to the 1930s. He was referred to the ISGS Applied Geophysics Section for information about geophysical techniques that might be more cost-effective than a drilling program in locating mine workings beneath the plant site. (Contact: D. Morse)

Highlights Archive

Updated 07/18/2012 SLD