MARLIN, DONALD J., Marlin Geological Associates, Houston, TX; WILLIAM H. SCHRAMM, Louisiana Department of Environmental Quality, Baton Rouge, LA; and ROBERT M. MAYER, Geophysical Microcomputer Applications, Inc., Houston, TX
Abstract: 3-D Seismic Applications for Environmental and Groundwater Reconnaissance
An analysis of current 3-D seismic exploration methods indicates a potentially useful application in environmental remediation and groundwater aquifer reconnaissance using data coverage that is commonly unused at depths less than 1500 ft (457 m). Hundreds of square mi of shallow surface data not useful for oil and gas exploration may be available via proprietary, brokered, and public sources.
3-D seismic data is generated from a grid of near-surface explosive or vibrational sources and recorded into a grid of nearlinear receiver lines. Commonly, 36 or more, 3 in (7.6 cm), 100 ft (30.5 m) source holes per square mi are drilled. The seismic is processed to enhance signal record providing as dense as 55 ft (16.7 m) bin or trace spatial resolution. The wavelet of the seismic trace can be isolated, extracted, and modeled against a myriad of actual borehole data (i.e., electric, drilling, borehole cuttings, and mud log information) to identify events that can be interpreted in areas of no control.
Frequency attenuates with depth, therefore, high resolution, if not overprinted by the acquisition footprint, can be obtained in the shallow subsurface (less than 500 ft (152.5 m)). After static correction to adjust the seismic trace data for surface irregularities, shallow time slices (that mimic low-relief topography) illustrate anomalies with patterns that suggest stratigraphic and structural variations. Examples from onshore Texas and Louisiana 3-D acquisitions illustrate the potential for predicting shallow sub-surface geologic and hydrogeologic conditions.
AAPG Search and Discovery Article #90924©1999 GCAGS Annual Meeting Lafayette, Louisiana