USGS Groundwater Information: Branch of Geophysics
As part of its applied research initiatives, the USGS Office of Ground Water, Branch of Geophysics (OGW BG) assists in the planning and collection of geophysical logs at the USGS Toxic Substances Hydrology Program's Naval Air Warfare Center (NAWC) research site in New Jersey, where volatile organic compounds have contaminated bedrock. This is an ongoing applied research project conducted in collaboration with other USGS Toxic Substances Hydrology Program scientists.
OGW BG applied geophysical logging research at NAWC is focused on the acquisition of comprehensive suites of standard and advanced borehole geophysical logs. The geophysical data are entered into a database accessible by USGS personnel involved in research at the NAWC site in order to support integrated, interdisciplinary research.
OGW BG has conducted a wide range of borehole geophysical surveys at the NAWC site since 2002.
Ongoing borehole geophysical logging has included standard logs such as caliper, electromagnetic (EM) induction, conductivity/resistivity, fluid resistivity, and fluid temperature. Data are used to aide in the development of the site conceptual framework, in the design of straddle-packer hydraulic tests, and in well completion.
Emphasis is being placed on integration of optical-televiewer (OTV), acoustic-televiewer (ATV), and heat-pulse flowmeter (HPFM) advanced logs with standard borehole logs using single-well and multi-well geophysical software. This integration allows for an improved, integrated analysis of all the logs. In this process, OGW BG scientists have worked to train USGS personnel from the New Jersey Water Science Center on techniques to acquire and analyze advanced logs.
Alton Anderson (USGS NY WSC) and John Williams (USGS OGW BG) prepare to conduct gamma spectral logging surveys at NAWC research site.
Additional work since 2002 has been directed toward obtaining estimates of formation porosity to support research on matrix diffusion and the application of borehole geophysical methods to support litho-typing of the gamma signatures used to develop the stratigraphic framework of the site. Logging methods used in these efforts include neutron, full waveform sonic, and spectral gamma as well as standard methods. Emphasis is being placed on logging of selected boreholes from which cores were extracted for laboratory physical property analysis. The information from these new and advanced tools is being used to identify and correlate unique lithologic signatures across fault boundaries and to correlate the geologic framework of the NAWC site to larger, basin-scale investigations.
Neutron logging of selected wells at the site in 2002 was conducted in collaboration with the USGS Borehole Geophysics Research Project.
Flowmeters were used to collect vertical flow profiles under ambient and stressed (pumped) conditions. The profiles indicate where water enters and exits the borehole. These flowmeter profiles, along with open-hole water-level data, were analyzed to determine the location, transmissivity, and head of discrete fractures, fracture zones, or bedding planes. These tests were conducted prior to installation of permanent or temporary well completions at NAWC. The results were used in the characterization of contaminant distribution and in the design of well completions and groundwater sampling plans.
Cross-borehole flow tests were completed at the NAWC study area in 2005 to 2007 to provide insights into hydraulic connections in fractured and dipping mudstone and sandstone bedrock at the site. The combined use of cross-hole flowmeter logging and water-level monitoring proved to be crucial for characterizing hydraulics and fracture network connectivity in the contaminated fractured bedrock aquifer.
Applied borehole geophysical research at NAWC is ongoing. Initial results and conclusions include the following:
This research was funded by the USGS Toxic Substances Hydrology Program.
Williams, J.H., Lacombe, P.J., Johnson, C.D., and Paillet, F.L., 2007, Cross-borehole flow tests and insights into hydraulic connections in fractured mudstone and sandstone, in Symposium on the Application of Geophysics to Engineering and Environmental Problems, April 1-5, 2007, Denver, Colorado, Proceedings 2007: Denver, Colorado, Environmental and Engineering Geophysical Society, CD-ROM, p. 1140-1152.
Johnson, C.D., and Williams, J.H., 2006, Use of cross-hole flowmeter logging to characterize fracture connectivity and fracture flow during a pumping test at the NAWC site, West Trenton, New Jersey [abs.]: Geological Society of America Abstracts with Programs, v. 38, no. 7, p. 528, Paper no. 219-10.
Johnson, C.D., Williams, J.H., and Anderson, J.A., 2007, Use of single- and cross-hole flowmeter logging for investigations in contaminated fractured-rock aquifers [abs.]: Proceedings of the Northeast Section Annual Meeting, Durham, New Hampshire, March 12-14, 2007, Geological Society of America.
For more information on this project, please contact John W. Lane, Jr. (Chief, USGS OGW Branch of Geophysics) or Carole Johnson (Hydrologist, USGS OGW Branch of Geophysics), or call the Branch of Geophysics at (860)487-7402.