Skip-spread method for seismic surveying

Claim 1

A method of marine seismic exploration wherein a seismic spread having a plurality of seismic detectors evenly spaced along the length thereof is towed through a body of water by a vessel, said seismic spread having leading and trailing extremities, seismic data recording means being provided and including a lesser number of recording channels than the number of said seismic detectors, said method comprising: towing said spread through the body of water at an optimum constant speed for efficient data acquisition; generating successive seismic waves at a shotpoint fixedly located with respect to said seismic spread as said spread is moved through said body of water, said seismic waves being generated at intervals equal to selected integral multiples of one half of the spacing of said seismic detectors; switching said recording channels at detector intervals corresponding to said selected integral multiples along said seismic spread after each seismic wave generation to a different selected group of said detectors; continuing said seismic wave generation and switching of said recording channels during a first predetermined length of movement of said seismic spread; discontinuing generation of seismic waves and switching of said recording channels during a second predetermined length of movement of said seismic spread; and towing said seismic spread through said body of water at a speed in excess of said optimum constant speed during said second predetermined length of movement of said seismic spread.

Claim 2

A method of marine seismic exploration wherein a seismic spread having a plurality of seismic detectors evenly spaced along the length thereof is towed through a body of water by a vessel, said seismic spread having leading and trailing extremities, seismic data recording means being provided and including a lesser number of recording channels than the number of said seismic detectors, said method comprising: towing said spread through the body of water at an optimum constant speed for efficient data acquisition; generating successive seismic waves at a shotpoint fixedly located with respect to said seismic spread as said spread is moved through said body of water, said seismic waves being generated at intervals equal to selected integral multiples of one half of the spacing of said seismic detectors; switching said recording channels at detector intervals corresponding to said selected integral multiples along said seismic spread after each seismic wave generation to a different selected group of said detectors; continuing said seismic wave generation and switching of said recording channels during a first predetermined length of movement of said seismic spread; discontinuing generation of seismic waves and switching of said recording channels during a second predetermined length of movement of said seismic spread; and towing said seismic spread through said body of water at a speed in excess of said optimum constant speed during said second predetermined length of movement of said seismic spread.

Claim 7

A method of marine seismic exploration wherein a seismic spread having a plurality of seismic detectors evenly spaced along the length thereof is towed through a body of water by a vessel, said seismic spread having leading and trailing extremities, seismic data recording means being provided and including a lesser number of recording channels than the number of said seismic detectors, said method comprising: towing said spread through the body of water at an optimum constant speed for efficient data acquisition; initiating data acquisition with said recording channels connected to the leading ones of said number of seismic detectors in said seismic spread; generating successive seismic waves at a shotpoint fixedly located with respect to said seismic spread as said spread is moved through said body of water; switching said recording channels at detector intervals corresponding to said shotpoint spacing toward the trailing extremity of said seismic spread after each seismic wave generation; continuing said seismic wave generation and switching of said recording channels during a first predetermined length of movement of said seismic spread; discontinuing generation of seismic waves and switching of said recording channels during a second predetermined length of movement of said seismic spread; and towing said seismic spread through said body of water at a speed in excess of said optimum constant speed during said second predetermined length of movement of said seismic spread.

Claim 8

A method of marine seismic exploration wherein a seismic spread having a plurality of seismic detectors evenly spaced along the length thereof is towed through a body of water by a vessel, said seismic spread having leading and trailing extremities, seismic data recording means being provided and including a lesser number of recording channels than the number of said seismic detectors, said method comprising: towing said spread through the body of water at an optimum constant speed for efficient data acquisition; initiating data acquisition with said recording channels connected to the leading ones of said number of seismic detectors in said seismic spread; generating successive seismic waves at a shotpoint fixedly located with respect to said seismic spread as said spread is moved through said body of water; switching said recording channels at detector intervals corresponding to said shotpoint spacing toward the trailing extremity of said seismic spread after each seismic wave generation; continuing said seismic wave generation and switching of said recording channels during a first predetermined length of movement of said seismic spread; discontinuing generation of seismic waves and switching of said recording channels during a second predetermined length of movement of said seismic spread; and towing said seismic spread through said body of water at a speed in excess of said optimum constant speed during said second predetermined length of movement of said seismic spread.

Claim 11

A method of marine seismic exploration wherein a seismic spread having a plurality of seismic detector means evenly spaced along the length thereof is towed through a body of water by a vessel, said seismic spread having leading and trailing extremities, seismic data recording means being provided and including a lesser number of recording channels than the number of said seismic detectors, said method comprising: towing said seismic spread through the body of water at an optimum constant speed for efficient data acquisition; generating successive seismic waves at a shotpoint located at a particular interval ahead of the first of said seismic detector means as said seismic spread is moved through said body of water; initiating data acquisition with said recording channels connected to the leading ones of said number of seismic detector means in said seismic spread; switching each of said recording channels one detector interval toward the trailing extremity of said seismic spread after each seismic wave generation; continuing said seismic wave generation and said switching of said recording channels until all of said seismic detectors have been selectively activated; discontinuing generation of seismic waves and switching of said recording channels during a predetermined length of movement of said seismic spread through the water; and towing said seismic spread through said body of water at a speed in excess of said optimum constant speed during said predetermined length of movement of said seismic spread.

Claim 12

A method of marine seismic exploration wherein a seismic spread having a plurality of seismic detector means evenly spaced along the length thereof is towed through a body of water by a vessel, said seismic spread having leading and trailing extremities, seismic data recording means being provided and including a lesser number of recording channels than the number of said seismic detectors, said method comprising: towing said seismic spread through the body of water at an optimum constant speed for efficient data acquisition; generating successive seismic waves at a shotpoint located at a particular interval ahead of the first of said seismic detector means as said seismic spread is moved through said body of water; initiating data acquisition with said recording channels connected to the leading ones of said number of seismic detector means in said seismic spread; switching each of said recording channels one detector interval toward the trailing extremity of said seismic spread after each seismic wave generation; continuing said seismic wave generation and said switching of said recording channels until all of said seismic detectors have been selectively activated; discontinuing generation of seismic waves and switching of said recording channels during a predetermined length of movement of said seismic spread through the water; and towing said seismic spread through said body of water at a speed in excess of said optimum constant speed during said predetermined length of movement of said seismic spread.

Claim 16

A method of seismic exploration wherein a seismic spread having a plurality of seismic detector means evenly spaced along the length thereof is moved in one direction, said seismic spread having leading and trailing extremities, said detectors being capable of recording reflected seismic data at any time, said method comprising: moving said seismic spread in said one direction; initiating said seismic data acquisition with a contiguous group of said detector means being selected to detect and transmit seismic information for recording; switching said group of selected detector means an equivalent detector interval in a direction opposing said one direction subsequent to each seismic wave generation.

Claim 17

A method of seismic exploration wherein a seismic spread having a plurality of seismic detector means evenly spaced along the length thereof is moved in one direction, said seismic spread having leading and trailing extremities, said detectors being capable of recording reflected seismic data at any time, said method comprising: moving said seismic spread in said one direction; initiating said seismic data acquisition with a contiguous group of said detector means being selected to detect and transmit seismic information for recording; switching said group of selected detector means an equivalent detector interval in a direction opposing said one direction subsequent to each seismic wave generation.

Claim 18

A method of seismic exploration wherein a seismic spread having a plurality of seismic detector means evenly spaced along the length thereof is moved in one direction, said seismic spread having leading and trailing extremities, said detectors being capable of recording reflected seismic data at any time, said method comprising: moving said seismIc spread in said one direction; initiating said seismic data acquisition with a contiguous group of said detector means being selected to detect and transmit seismic information for recording said contiguous group of said detector means beginning with the first of said detector means; generating successive seismic waves at source positions being fixedly located with respect to said seismic spread as said spread is moved; and switching said group of selected detector means in a direction opposing said one direction subsequent to each seismic wave generation said switching being accomplished by movement of said contiguous group of said active detector means a detector interval corresponding to the detector interval of said source positions in a direction opposing movement of said spread subsequent to each seismic wave generation.

Claim 19

A method of seismic exploration wherein a seismic spread having a plurality of seismic detector means evenly spaced along the length thereof is moved in one direction, said seismic spread having leading and trailing extremities, said detectors being capable of recording reflected seismic data at any time, said method comprising: moving said seismIc spread in said one direction; initiating said seismic data acquisition with a contiguous group of said detector means being selected to detect and transmit seismic information for recording said contiguous group of said detector means beginning with the first of said detector means; generating successive seismic waves at source positions being fixedly located with respect to said seismic spread as said spread is moved; and switching said group of selected detector means in a direction opposing said one direction subsequent to each seismic wave generation said switching being accomplished by movement of said contiguous group of said active detector means a detector interval corresponding to the detector interval of said source positions in a direction opposing movement of said spread subsequent to each seismic wave generation.

Claim 21

A method of marine seismic exploration for achieving continuous multiple fold coverage of a subsurface environment wherein a seismic spread having a seismic source and a plurality of seismic detectors evenly spaced along the length thereof is towed along a traverse having uniformly spaced locations and a contiguous group of recording channels is employed to receive signals from selected contiguous groups of said seismic detectors, said method comprising: a. towing the seismic spread through the body of water at an optimum constant speed for efficient data acquisition; b. successively exciting the seismic source at a first predetermined number of consecutive uniformly spaced locations and recording the seismic signals received by the plurality of seismic detectors; c. switching said recording channels one detector interval along said seismic spread after each seismic excitation; d. increasing the speed of the seismic spread through the water without recording seismic signals from a second predetermined number of consecutive locations at uniformly spaced locations; e. reducing the towing speed of the seismic spread to the optimum constant speed; and f. successively exciting the seismic source at the first predetermined number of consecutive locations at uniformly spaced locations and recording the seismic signals received by the plurality of seismic detectors.

Claim 22

A method of marine seismic exploration for achieving continuous multiple fold coverage of a subsurface environment wherein a seismic spread having a seismic source and a plurality of seismic detectors evenly spaced along the length thereof is towed along a traverse having uniformly spaced locations and a contiguous group of recording channels is employed to receive signals from selected contiguous groups of said seismic detectors, said method comprising: a. towing the seismic spread through the body of water at an optimum constant speed for efficient data acquisition; b. successively exciting the seismic source at a first predetermined number of consecutive uniformly spaced locations and recording the seismic signals received by the plurality of seismic detectors; c. switching said recording channels one detector interval along said seismic spread after each seismic excitation; d. increasing the speed of the seismic spread through the water without recording seismic signals from a second predetermined number of consecutive locations at uniformly spaced locations; e. reducing the towing speed of the seismic spread to the optimum constant speed; and f. successively exciting the seismic source at the first predetermined number of consecutive locations at uniformly spaced locations and recording the seismic signals received by the plurality of seismic detectors.

Claim 24

A method of seismic exploration for achieving continuous multiple fold coverage of a subsurface environment wherein a seismic spread having a seismic source and a plurality of seismic detectors evenly spaced along the length thereof is located along a traverse having uniformly spaced locations and a contiguous group of recording channels is employed to receive signals from selected contiguous groups of said seismic detectors, said method comprising: a. locating the seismic spread along the traverse with the source located in relation to one of the uniformly spaced locations; b. exciting the source and recording the signals received from a selected consecutive series of the plurality of seismic detectors; c. relocating the seismic spread along the traverse with the seismic source located in the same relation to the next of the uniformly spaced locations along the traverse; d. selecting a different consecutive series of said seismic detectors following each excitation of said source; e. repeating step (b) exciting the source and recording the signals received from said different consecutive series of said seismic detectors; f. repeating steps (c), (d) and (e) forming a first predetermined number of recordings from consecutive uniformly spaced locations; g. skipping a second predetermined number of consecutive uniformly spaced locations without exciting the source at the locations skipped; and h. successively repeating step (f) then step (g) along the traverse.

Claim 25

A method of seismic exploration for achieving continuous multiple fold coverage of a subsurface environment wherein a seismic spread having a seismic source and a plurality of seismic detectors evenly spaced along the length thereof is located along a traverse having uniformly spaced locations and a contiguous group of recording channels is employed to receive signals from selected contiguous groups of said seismic detectors, said method comprising: a. locating the seismic spread along the traverse with the source located in relation to one of the uniformly spaced locations; b. exciting the source and recording the signals received from a selected consecutive series of the plurality of seismic detectors; c. relocating the seismic spread along the traverse with the seismic source located in the same relation to the next of the uniformly spaced locations along the traverse; d. selecting a different consecutive series of said seismic detectors following each excitation of said source; e. repeating step (b) exciting the source and recording the signals received from said different consecutive series of said seismic detectors; f. repeating steps (c), (d) and (e) forming a first predetermined number of recordings from consecutive uniformly spaced locations; g. skipping a second predetermined number of consecutive uniformly spaced locations without exciting the source at the locations skipped; and h. successively repeating step (f) then step (g) along the traverse.