Patent Document ID: 20100027377
Application ID: 11669954
Patent Flag: 0

Claim One:
1. A method to locate and dimension qualitatively an oil, gas or water saturated zone in the earth, by extracting its characteristic resonance response to an actively applied excitation in the range of 1-20 Hz, said method comprising the steps 1. Apply artificial excitation energy to an area to be surveyed for fluid saturated ground, in a predetermined manner typically used in geophysical exploration, such that it efficiently excites present resonators, due to fluid presence, into oscillation, constituting an oscillator, and in a way that the so excited oscillations are not obscured by the excitation itself, while 2. simultaneously measure over this survey area with long period seismometers producing seismograms, spacing chosen not larger then wave length of interest, all locations chosen to avoid local noise and buried to avoid wind noise, 3. correct said seismograms for local impedance changes, effect of topography, 4. perform a main analysis of said seismograms in the frequency domain, frequency and phase to identify excited oscillators resp. resonators, including their qualitative strength, by (a) define time average signal characteristics magnitude, phase in the frequency domain over the entire duration of individual measurements, and along the processing deduce a regional velocity structure from seismograms, via velocity correlation coefficients, resulting in a velocity dispersion curve assuming a random wave field, and invert it to a velocity structure with depth, (b) use a horizontal/vertical ratio test in said seismograms to exclude oscillators related to rock layering and rock structures alone, unrelated to fluid saturated areas, as the horizontal to vertical component ratio in a seismogram spectrum reaches a maximum for rock structure oscillations, (c) examine signal characteristics with shifted time windows, of size 1.5-30 sec to determine frequency peaks excited in step 1, including amplitude, sharpness, duration optionally phase behavior, use frequency peak repetitiveness to isolate oscillators due to excitation as deviations in statistics, also isolate frequency peaks of excited oscillators by use of a frequency/time/strength plot and optionally extract oscillations of detected frequencies peaks for further processing, (d) use the Sompi method, a unique way to identify oscillators in waves independent of Fourier analysis, based solely on linear intrinsic mechanism of oscillations, on said seismograms, with or without filtering resulting from steps b and c to determine excited, if any oscillators and parameters frequency f and quality Q, (e) correlate shape and amplitude of signal to a depth indicator, related to the smoothness in the amplitude distribution, for the excited oscillator, (f) map frequency f from (a), (c), Q from (d), depth indicator from (e) over the survey area, thereby identifying suspect signal areas indicating resonance resp. oscillator bodies, and g) set up and use mean, variance, distribution in time and space statistics for comparison of found oscillator data frequency f, quality Q, depth indicator, frequency maxima from seismograms between different areas where additional details are known: depth, fluid type, dimensions of fluid area to deduce further characteristics in case of a match, wherein, as a result, qualitatively identify and map regionally excited oscillators defined by frequency peaks and associated quality Q, which are related to and therefore indicate fluid saturated ground, since rock related effects were excluded in processing (4b).