US4136754A — Process for seismic exploration by means of a dir…

Claim 1

Independent Claim 254 words

A process of seismic exploration in an environment comprising at least one subsoil layer, a medium capable of propagating seismic disturbances superimposed on said subsoil layer, and a terrestrial atmosphere superimposed on said medium, wherein each elementary measurement of the exploration comprises the steps of: positioning a plurality of seismic disturbance sources Sj (j = 1 to n) in spaced relation in said medium at various depths in relation to the interface of said medium with said terrestrial atmosphere; positioning seismic collectors to receive seismic signals resulting from reflections of said disturbances propagated in said subsoil; emitting seismic disturbances from said sources; and receiving at said collectors said disturbances reflection signals, wherein positioning said sources further comprises selecting the respective source depths and spacings so that the average ratio F.sub.θ (f) of the spectral density A.sub.θ (f) of seismic disturbance power transmitted in a predetermined direction to the spectral density A 0 (f) of seismic disturbance power transmitted vertically downwardly, for a predetermined band of frequencies, is less than about -20 dB, where Aθ(f) = modulus of ##EQU5## and A 0 (f) = modulus of ##EQU6## n being the number of sources, Xj (j = 1 to n) and Pj (j = 1 to n) being respectively the abcissas and depths of the respective sources, v 1 being the propagation speed of seismic disturbances in said medium, f being a frequency in the spectral band of the disturbances emitted by the sources, and θ being the angle between the vertical and said predetermined direction.

Claim 2

Dependent Claim 254 words

A process of seismic exploration in an environment comprising at least one subsoil layer, a medium capable of propagating seismic disturbances superimposed on said subsoil layer, and a terrestrial atmosphere superimposed on said medium, wherein each elementary measurement of the exploration comprises the steps of: positioning a plurality of seismic disturbance sources Sj (j = 1 to n) in spaced relation in said medium at various depths in relation to the interface of said medium with said terrestrial atmosphere; positioning seismic collectors to receive seismic signals resulting from reflections of said disturbances propagated in said subsoil; emitting seismic disturbances from said sources; and receiving at said collectors said disturbances reflection signals, wherein positioning said sources further comprises selecting the respective source depths and spacings so that the average ratio F.sub.θ (f) of the spectral density A.sub.θ (f) of seismic disturbance power transmitted in a predetermined direction to the spectral density A 0 (f) of seismic disturbance power transmitted vertically downwardly, for a predetermined band of frequencies, is less than about -20 dB, where Aθ(f) = modulus of ##EQU5## and A 0 (f) = modulus of ##EQU6## n being the number of sources, Xj (j = 1 to n) and Pj (j = 1 to n) being respectively the abcissas and depths of the respective sources, v 1 being the propagation speed of seismic disturbances in said medium, f being a frequency in the spectral band of the disturbances emitted by the sources, and θ being the angle between the vertical and said predetermined direction.

Claim 3

Dependent Claim 33 words

The process of claim 1, further comprising the step of registering in a given time interval the compound signals resulting from superposition of reflections of the various disturbances emitted during the elementary measurement.

Claim 4

Dependent Claim 11 words

The process of claim 1 wherein said medium comprises a liquid.

Claim 5

Dependent Claim 11 words

The process of claim 1 wherein said medium comprises a solid.

Claim 6

Dependent Claim 37 words

The process of claim 1, wherein the positions selected for said sources are positions for which the function F.sub.θ (f) for a band of frequencies of about 1 octave has an average value less than about -20dB.

Claim 7

Dependent Claim 15 words

The process of claim 1, wherein said sources are simultaneously activated to emit seismic disturbances.

Claim 8

Dependent Claim 108 words

The process of claim 1 wherein said sources are activated to emit seismic disturbances at respective times tj (j = 1 to n) from a common temporal origin, said times tj being chosen such that the function G.sub.θ '(f) = B.sub.θ '(f)/B 0 (f) will be on the average appreciably less than 1 for said predetermined band of frequencies, with ##EQU7## wherein θ' is an angle equal to or not equal to θ between the vertical and a direction along which it is desired that the spectral density of seismic disturbance power transmitted will be appreciably less than the spectral density of seismic disturbance power transmitted vertically downwardly.

Claim 9

Dependent Claim 42 words

The process of claim 7 wherein the sine of angle θ' is substantially equal to the ratio of the propagation speed of seismic disturbances in said medium to the propagation speed of seismic disturbances in at least one of said subsoil layers.

Claim 10

Dependent Claim 57 words

The process of claim 7 wherein the groups of values t j (j = 1 to n) are varied from one said elementary measurement to the next in order to vary said angle θ', whereby the direction for which said ratio of average spectral densities is minimized is also varied from one elemental measurement to the next.

Claim 11

Dependent Claim 48 words

The process of claim 1 wherein the sine of the angle between said predetermined direction and the vertical is substantially equal to the ratio of the propagation of seismic disturbances in said medium to the propagation speed of seismic disturbances in at least one of said subsoil layers.

Claim 12

Dependent Claim 65 words

The process of claim 1 wherein said sources have various respective seismic disturbance emission amplitudes, said amplitudes being chosen so as to increase the ratio of the average spectral density of seismic disturbance power transmitted vertically downwardly to the average spectral density of seismic disturbance power transmitted in said predetermined direction over the value of this ratio for sources having uniform seismic disturbance emission amplitudes.

Claim 13

Dependent Claim 99 words

A process of seismic exploration in an environment comprising at least one subsoil layer, a medium capable of propagating seismic disturbances superimposed on said subsoil layer, and a terrestrial atmosphere superimposed on said medium, wherein each elementary measurement of the exploration comprises the steps of: positioning a plurality of seismic disturbances sources within said medium along at least one curved line, said line having upwardly turned concavity; positioning seismic collectors to receive seismic signals resulting from reflections of said disturbances propagated in said subsoil; emitting seismic disturbances from said sources, and receiving at said collectors said disturbance reflection signals.

Claim 14

Dependent Claim 99 words

A process of seismic exploration in an environment comprising at least one subsoil layer, a medium capable of propagating seismic disturbances superimposed on said subsoil layer, and a terrestrial atmosphere superimposed on said medium, wherein each elementary measurement of the exploration comprises the steps of: positioning a plurality of seismic disturbances sources within said medium along at least one curved line, said line having upwardly turned concavity; positioning seismic collectors to receive seismic signals resulting from reflections of said disturbances propagated in said subsoil; emitting seismic disturbances from said sources, and receiving at said collectors said disturbance reflection signals.

Claim 15

Dependent Claim 26 words

The process of claim 12, further comprising registering in a given time interval the compound signals resulting from superposition of reflections of the various disturbances emitted.

Claim 16

Dependent Claim 11 words

The process of claim 12 wherein said medium is a liquid.

Claim 17

Dependent Claim 11 words

The process of claim 12 wherein said medium is a solid.

Claim 18

Dependent Claim 15 words

The process of claim 12 wherein said sources are in spaced relation along said line.

Claim 19

Dependent Claim 15 words

The process of claim 16 wherein the spacing between said sources varies along said line.

Claim 20

Dependent Claim 56 words

The process of claim 16 wherein the respective positions of said sources are chosen such that the average spectral density of seismic disturbance power transmitted in a predetermined non-vertical direction is appreciably less than the average spectral density of seismic disturbance power transmitted vertically downwardly, said average spectral densities being for a predetermined band of frequencies.

Claim 21

Dependent Claim 50 words

The process of claim 18 wherein the sine of the angle between said predetermined non-vertical direction and the vertical is substantially equal to the ratio of the propagation speed of seismic disturbances in said medium to the propagation speed of seismic disturbances in at least one of said subsoil layers.

Claim 22

Dependent Claim 78 words

The process of claim 18 wherein the emission of disturbances from the various sources is made at various times with respect to a temporal origin, said times being chosen so as to reduce the ratio of the average spectral density of seismic disturbance power transmitted in said predetermined non-vertical direction to the average spectral density of seismic disturbance power in the vertical direction from the value of said ratio for simultaneous emission of seismic disturbances from said sources.

Claim 23

Dependent Claim 15 words

The process of claim 12 wherein said curved line is in a substantially vertical plane.

Claim 24

Dependent Claim 28 words

The process of claim 12 wherein said plurality of sources is positioned along a plurality of curved lines so as to define a cup-shaped configuration having upwardly-turned concavity.

Claim 25

Dependent Claim 143 words

An arrangement for seismic exploration in an environment comprising at least one subsoil layer, a medium capable of propagating seismic disturbances superimposed on said subsoil layer, and a terrestrial atmosphere superimposed on said medium, comprising: a plurality of seismic disturbance sources positioned in spaced relation in said medium at various depths in relation to the interface of said medium with said terrestrial atmosphere and along at least one curved line, said curved line having upwardly turned concavity, the positions of said sources being such that the ratio of the average spectral density of seismic disturbance power transmitted vertically downwardly by the plurality of sources to the average spectral density of seismic disturbance power in a predetermined non-vertical direction, for a predetermined band of frequencies, will be greater than the value of this ratio for a plurality of sources positioned at a uniform depth.

Claim 26

Dependent Claim 143 words

An arrangement for seismic exploration in an environment comprising at least one subsoil layer, a medium capable of propagating seismic disturbances superimposed on said subsoil layer, and a terrestrial atmosphere superimposed on said medium, comprising: a plurality of seismic disturbance sources positioned in spaced relation in said medium at various depths in relation to the interface of said medium with said terrestrial atmosphere and along at least one curved line, said curved line having upwardly turned concavity, the positions of said sources being such that the ratio of the average spectral density of seismic disturbance power transmitted vertically downwardly by the plurality of sources to the average spectral density of seismic disturbance power in a predetermined non-vertical direction, for a predetermined band of frequencies, will be greater than the value of this ratio for a plurality of sources positioned at a uniform depth.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1982-01-29	1982-07-31	1983-01-30	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1986-01-29	1986-07-31	1987-01-30	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1990-01-29	1990-07-31	1991-01-30	$7700.00	Window Closed / Lapsed

Process for seismic exploration by means of a directive source

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