Method of exploring a region below a surface of the earth

摘要

A passive method for exploring a region below the surface of the earth. The method comprises using a plurality of sensors to obtain seismic data obtained by recording ambient seismic interface waves in a frequency range whose lower limit is greater than 0 Hz, and whose upper limit is less than or equal to substantially 1 Hz. The sensors may be sensitive to three orthogonal components. Recordings may be made simultaneously by all sensors and normalization of data is unnecessary. The sensors may be moved and clean data may be selected. Local dispersion curves may be determined to improve vertical resolution. The data are processed so as to obtain a measure of the energy in a frequency band within the frequency range. The energy measure may be calculated by integrating the spectrum in the frequency domain over a desired frequency range. The resulting calculated energy provides information about the region of the earth being explored.

主权项

1. A method of conducting a survey to explore a subsurface region below a surface of the Earth, comprising: placing a plurality of sensors at respective sensor locations to obtain seismic data by recording ambient seismic waves at said respective sensor locations, moving at least some of said sensors during the survey to a plurality of different respective sensor locations in turn to form a plurality of different, successive combinations of sensor locations, each of said successive combinations of sensor locations including at least one sensor location that is a same sensor location as in the just previous combination of sensor locations, and making at each combination of sensor locations at least partially simultaneous recordings with each sensor to obtain seismic data, each said sensor being sensitive in a frequency range whose lower limit is greater than or equal to 0 Hz and whose upper limit is less than or equal to 1 Hz; and processing a vertical component of said data to obtain an amplitude of energy in a frequency band within said frequency range to obtain information relating to an interface in the region and to display an image of the subsurface region.