HR: 0830h
AN: NS51A-05    [Abstracts]
TI: Development of an Innovative Downhole Seismic Source
AU: * Reichhardt, D
EM: david.reichhardt@mse-ta.com
AF: MSE Technology Applications, Inc., 200 Technology Way, Butte, MT 59701 United States
AB: MSE Technology Applications, Inc. (MSE) previously designed, built, and tested an innovative downhole seismic source. The design criteria included a size limitation (the source needed to fit into a 2-inch diameter well casing), the source would use .22 caliber power loads as the energy source, it would have the ability to fire at least 12 times before reloading, it would be able to function under water (depth is limited by internal pressure from the .22 caliber power loads, which must be greater than pressure exerted by water column), and it would use no more than 24-volt dc current. MSE developed the design criteria from a need for a downhole seismic source suitable for high-resolution seismic tomography applications. Tomographic methods may provide detailed information at waste sites for both characterization and monitoring. Since borehole diameters are kept to a minimum (i.e., 2-inches or less) to reduce waste volumes from drill cuttings, or the borehole may be installed using a direct push technology such as a GeoprobeT or cone penetrometer, a small diameter source is desirable. Additionally, the use of .22 caliber power loads reduces the amount of supporting equipment required to operate the source as compared to other downhole seismic sources (e.g., air guns and piezoelectric sources). MSE tested and evaluated the completed seismic source to assess the effectiveness of the .22 caliber power loads as energy sources and to assess the operational ease of using the source. Results of the testing indicated that the power loads provided energy suitable for high-resolution cross-well seismic tomography applications. Operation of the source required significantly less supporting equipment than other downhole sources tested. However, the testing suggested the system could be improved if the number of mechanical components were reduced. Subsequent research suggested that the power loads could be fired using an electric current. As a result, MSE believes that the entire operation of the seismic source could be accomplished using electronic components. This would eliminate mechanical components currently used inside the seismic source. Planned borehole seismic source modifications include converting the source from primarily mechanical operation to electrical operation and completing the firing control system. The firing control system will allow the user to turn the source on and off, initiate the firing process, and track the number of power loads fired. Testing of the modified seismic source will be limited to bench testing the electronic firing mechanism and the firing control system since we are not modifying the energy source used (.22 caliber power loads) performance of the source in this respect will not change. Acknowledgements Work is being conducted through the Savannah River Operations office at the Western Environmental Technology Office under DOE Contract Number DE-AC09-96EW96405.
DE: 0994 Instruments and techniques
SC: Near-Surface Geophysics [NS]
MN: 2005 Joint Assembly