Method of three dimensional seismic prospecting

The method of seismic prospecting comprising;

• (a) providing a first selected reference signal R1(t) fora vibratory source, of selected time duration D1;
• (b) inverting the polarity of said reference signal during a selected portion of said duration D1 to form a first modified reference signal R1(t);
• (c) radiating a first seismic signal into the earth responsive to said first modified reference signal, R1(t) at a first point on the earth;
• (d) receiving the seismic signal radiated at said first point, at a second point distant from said first point, to provide a first received signal;
• and
• (e) correlating said first received signal with said modified first reference signal R1(t).

The method of seismic prospecting comprising;

• (a) providing a first selected reference signal R1(t) for a vibratory seismic source, of selected time duration D1;
• (b) inverting the polarity of said reference signal during a selected portion of said duration D1 to form a first modified reference signal R1(t);
• (c) radiating a first seismic signal into the earth responsive to said first modified reference signal, R1(t) at a first point on the earth;
• (d) radiating a second seismic signal of time duration D2 into the earth responsive to a second reference signal R2(t) co-temporaneously with said first seismic signal, at a second point on the earth spaced from said first point;
• (e) receiving the seismic signals radiated at said first and second points, at a third point distant from said first and second points, to provide a first composite received signal, which includes components of both said first and second seismic signals;
• and
• (f) correlating said first composite received signal separately both with said modified first reference signal R1(t), and
• with said second reference signal, R2(t).

In the method of seismic prospecting in which at least a first and a second seismic source cotemporaneously radiate into the earth, first and second vibratory seismic signals responsive respectively to a first and to a second reference signal, at first and second spaced-apart points, respectively, which seismic signals are received at a third point spaced from said first and second points, to form a composite received signal, the method of separating from said composite received signal one of said first and second seismic signals comprising;

• (a) coding in a first selected manner said first reference signal prior to said radiation;
• (b) coding said composite received signal in a second selected manner related to said first selected manner, to provide a first coded composite received signal;
• (c) repeating the transmissions from said first and second sources, without coding either of said sources;
• and
• (d) producing a second uncoded composite received signal.

The method of seismic prospecting comprising

• (a) generating a first train of time-spaced unidirectional electrical pulses of continually changing time interval between adjacent pulses;
• (b) inverting alternate pulses of said train to provide a second train of alternately reversing electrical pulses;
• (c) responsive to said second train, applying to the earth a corresponding train of alternately reversing forces at a first point on the earth;
• and
• (d) detecting the seismic waves generated by said train of alternately reversing forces after passing through the earth, at a second point distant from said first point.