A Three-component Acquisition System

The fidelity of full vector seismic data acquired with systems of three-component (3C) receivers that are rigidly attached to an acquisition device is evaluated. The acquisition device is designed for rapid and cost-effective imaging of the upper 30m of the earth's surface. Multi-mode analysis of full vector seismic data has the potential to provide engineers and geophysicists with near-surface soil and rock properties such as unit thicknesses, strata geometry, strength, compressibility, fracture orientation, and pore-fluid content. Acquisition of the full vector wavefield using 3C receivers, however, is a timeand labor-intensive procedure. The approach of researchers at the University of Kansas has been to rigidly attach arrays of 3C Galperin receiver units to lengths of channel iron. The channel iron serves as an acquisition device that eliminates the need to individually plant, connect, vertically level, and horizontally orient each 3C unit. The acquisition device is modeled as a linear filtering mechanism. This allows the resulting crosstalk between receiver mounts to be approached as an inverse-filtering problem that requires determination of the transfer function of the device. Coincident acquisition of seismic data using both device-mounted and traditional spike-mounted 3C Galperin units provides a means to estimate the transfer function. Application of the inverse of this function to the device-mounted data results in field gathers that are fundamentally equivalent to those recorded with traditional spike-mounted 3C units. We conclude that the true seismic wavefield is neither lost nor destroyed by recording with device-mounted geophones and that this wavefield is recoverable through the well establish process of linear filtering.