Simultaneous use of pseudo-random control signals in vibrational exploration methods
AssigneeContinental Oil Company
InventorsCharles E. Payton, Kenneth H. Waters, Pierre L. Goupillaud
Life of this patent
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Abstract
A method for deriving seismic information through the simultaneous operation of a plurality of vibrational seismic energy source systems such that the information produced by each source system may be separated from the combined recorded information.
Claims9
A method of producing and processing seismic data by the simultaneous operation, within the same geologic neighborhood, of a plurality of vibrational seismic energy source systems and associated seismic energy receivers, each source system having at least one vibrational seismic energy source, comprising the steps of:
- positioning a plurality of vibrational seismic energy source systems and associated seismic energy receivers at predetermined locations along at least one selected line of survey within the same geologic neighborhood;
- constructing a distinctive control signal of non-linear pseudo-random character having predetermined frequency content and time duration for each of a predetermined number of said plurality of source systems, each of said distinctive control signals having the same amplitude spectrum and therefore the same autocorrelation functions;
- simultaneously operating at least two of said predetermined number of said plurality of source systems, each according to a distinctive control signal;
- recording all of the returned seismic energy generated by the plurality of simultaneously operating source systems;
- and,
- processing said recorded seismic energy so that the seismic data produced by each of the plurality of simultaneously operating source systems is separated by correlation from the recorded seismic energy.
A method for constructing a distinctive control signal, having predetermined frequency content and time duration, for controlling the energization of a vibrational seismic energy source system having at least one vibrational seismic energy source, comprising the steps of:
- generating a series of random numbers;
- and
- constructing a distinctive control signal comprised of a continuous alternating signal whose amplitude is a function of said series of random numbers.
A method for constructing a distinctive control signal, having predetermined frequency content and time duration, for controlling the energization of a vibrational seismic energy source system having at least one vibrational seismic energy source, comprising the steps:
- generating a series of random numbers, n.sub.f, wherein 0.ltoreq.n.sub.f .ltoreq.N;
- and
- constructing a distinctive control signal comprised of a continuous alternating signal of predetermined amplitude wherein the phase angle, .theta..sub.f, of each succeeding frequency of said control signal is a function of said series of random numbers according to the relation
- .theta..sub.f =.pi.(2n.sub.f -N)/N.
A method for constructing a distinctive control signal, having predetermined frequency content and time duration, for controlling the energization of a vibrational seismic energy source system having at least one vibrational seismic energy source, comprising the steps of:
- generating a series of random numbers, n.sub.f, wherein 0.ltoreq.n.sub.f .ltoreq.N;
- and
- constructing a distinctive control signal comprised of a continuous alternating signal wherein the ratio of the real, R.sub.f, and the imaginary, I.sub.f, parts of the amplitude, A.sub.f, is a function of said series of random numbers according to the relations
- A.sub.f =(R.sub.f.sup.2 +I.sub.f.sup.2).sup.1/2
- R.sub.f =n.sub.f /N
- i.sub.f =.+-.(1-R.sub.f.sup.2).sup.1/2.
A method for constructing a distinctive control signal, having predetermined frequency content and time duration, for controlling the energization of a vibrational seismic energy source system having at least one vibrational seismic energy source, comprising the steps of:
- constructing a continuous alternating control signal of predetermined time duration having predetermined frequency content;
- separating said control signal into a predetermined number of signal segments;
- and
- constructing a distinctive control signal by randomly combining end to end said signal segments.
Dependencies are inferred from the claim text.