Cross-Well Seismic Imaging

Task Description

This technology utilizes seismic imaging to gain a better under-
standing of remediation system performance. Seismic images provide a means to image geo-
logic conditions non-intrusively. By placing the seismic source and receivers downhole (in boreholes) on the sides of the area to be imaged, travel distance is reduc-
ed; this preserves higher seismic frequencies resulting in better resolution. Seismic travel times are measured among a great number (over 300) of source and receiver locations in the two bore-
holes (Figure 1.4). These travel times are then inverted into a two-
dimensional velocity through a

method known as tomography. Shear wave and compressional wave sources were used. Both sources are pneumatic devices and operate on a compressed gas line from gas cylinders at the sur-
face. The shear wave source is a controlled vibrator while the com-
pressional wave source is an impulse source. Comparison of the velocity structures for the compres-
sional and shear waves provides information about rock properties and fluid content.

Technology Needs

For all remediation technologies, a coherent image of the subsurface geology must be obtained to understand contaminant transport and to devise the proper remedia-
tion strategy. Much of this geologic