Sweep signal seismic exploration

Claim 2

Method of seismic exploration comprising: generating a signal of frequency changing with time, supplying said signal to a transducer whose mechanical output is positioned to transmit a mechanical vibratory signal to the earth in response to receipt of said signal by said transducer, receiving said mechanical vibratory signal transmitted through the earth, recording the received mechanical vibratory signal, repeating the foregoing steps once with reversed polarity of said generated signal, subtracting one received record from the other to produce a composite record, and cross-correlating said composite record.

Claim 3

repetition of the transmission of step (1) a number of times using a signal of reversed polarity during some of said repetitions,

Claim 4

repetition of the transmission of step (1) a number of times using a signal of reversed polarity during some of said repetitions,

Claim 5

Method according to claim 1 wherein the subtraction is effected by reversing the polarity of recording one of the received signals and then adding the records of such received signals.

Claim 6

Method according to claim 1 wherein the cycle of the first five steps enumerated in claim 1 is repeated for a plurality of cycles and the sum of alternate ones of all said received records is subtraCted from the sum of the others of said received records to produce said composite record.

Claim 7

recording receptions of said transmissions,

Claim 8

recording receptions of said transmissions,

Claim 9

Method according to claim 1 wherein the location of the transducer is changed after each cycle.

Claim 10

compositing the recordings in such a manner as to produce a composite equal to the sum of all the recordings of the receptions of said transmissions using reversed polarity signals subtracted from the sum of the recordings of the reception of the remainder of said transmissions, and

Claim 11

compositing the recordings in such a manner as to produce a composite equal to the sum of all the recordings of the receptions of said transmissions using reversed polarity signals subtracted from the sum of the recordings of the reception of the remainder of said transmissions, and

Claim 12

cross-correlating said composite of said recordings with said signal transmitted into the earth.

Claim 13

cross-correlating said composite of said recordings with said signal transmitted into the earth.

Claim 14

Method according to claim 1 wherein each said signal is a down sweep.

Claim 15

Method according to claim 5 wherein an odd number of sweeps, at least nine in number, is performed.

Claim 16

In the method of seismic exploration employing excitation means for generating an electric sweep signal, vibrator means responsive to the excitation means to generate and transmit to the earth a seismic sweep signal generally similar to said electric signal, seismometer means for receiving the seismic signal, e.g., when reflected or refracted from a sub-surface formation, and recording means for recording the output of the seismometer, wherein a series of sweep signals is generated by said excitation means, and the resultant series of seismic signals is recorded by said recording means and the series of recorded signals is composited prior to cross-correlation with the excitation signals, the improvement comprising reversing the polarity of excitation and recording on every other sweep, while maintaining constant the range of amplitude of each sweep compared to the other sweeps, and preferably but not necessarily performing an even number of sweeps.

Claim 17

In the method of seismic exploration employing excitation means for generating an electric sweep signal, vibrator means responsive to the excitation means to generate and transmit to the earth a seismic sweep signal generally similar to said electric signal, seismometer means for receiving the seismic signal, e.g., when reflected or refracted from a sub-surface formation, and recording means for recording the output of the seismometer, wherein a series of sweep signals is generated by said excitation means, and the resultant series of seismic signals is recorded by said recording means and the series of recorded signals is composited prior to cross-correlation with the excitation signals, the improvement comprising reversing the polarity of excitation and recording on every other sweep, while maintaining constant the range of amplitude of each sweep compared to the other sweeps, and preferably but not necessarily performing an even number of sweeps.

Claim 18

Method of siesmic exploration comprising: generating a signal of frequency changing with time, supplying said signal to a transducer whose mechanical output is positioned to transmit a mechanical vibratory signal to the earth in response to receipt of said signal by said transducer, receiving said mechanical vibratory signal transmitted through the earth, recording the received mechanical vibratory signal, repeating the foregoing steps once with reversed polarity of said generated signal, and reversed polarity of recording, repeating the cycle of the first five steps enumerated above for a plurality of cycles, producing a composite record by adding all of the records of said received signals, and cross-correlating said composite record.

Claim 19

Method of siesmic exploration comprising: generating a signal of frequency changing with time, supplying said signal to a transducer whose mechanical output is positioned to transmit a mechanical vibratory signal to the earth in response to receipt of said signal by said transducer, receiving said mechanical vibratory signal transmitted through the earth, recording the received mechanical vibratory signal, repeating the foregoing steps once with reversed polarity of said generated signal, and reversed polarity of recording, repeating the cycle of the first five steps enumerated above for a plurality of cycles, producing a composite record by adding all of the records of said received signals, and cross-correlating said composite record.

Claim 20

Method of seismic exploration comprising the steps of

Claim 21

Method of seismic exploration comprising the steps of

Claim 22

Method according to claim 9 wherein the transmissions using a signal of reversed polarity alternate with the other transmissions.

Claim 23

Method according to claim 9 wherein are composited recordings of transmissions using a signal of reversed polarity as nearly as possible equal in number to recordings of other transmissions.

Claim 24

Method according to claim 11 using an even number of recordings of said transmissions.

Claim 25

Method according to claim 10 using an even number of transmissions.