NONLINEAR ELECTROSEISMIC EXPLORATION

摘要

A method for seismic exploration using nonlinear conversions (e.g., item 6, Fig. 10) between electromagnetic and seismic energy. Seismic returns from a source waveform (e.g., item 180, Fig. 7A) are correlated with a reference waveform (item 150, Fig. 5B), with both waveforms designed to minimize both correlation side lobes and interference from linear electroseismic effects. A waveform element (e.g., item 10, Fig 1A) is selected to be sequenced by a binary or similar digital code designed to generate an input sweep with the needed depth penetration and noise suppression. Correlation of the seismic response with the reference waveform in a data processing step mathematically aggregates the seismic response from the input sweep into a single wavelet (e.g., item 160, Fig. 6A). Preferred binary digital codes include prescribed Britains of maximal length shift-register sequences (e.g., item 100, Fig. 3A). Also, an apparatus (items 152-157, Fig. 15) for generating the desired waveforms.