System for changing seismic detection array lengths

• US 3,887,897 A
• Filed: 07/23/1973
• Issued: 06/03/1975
• Est. Priority Date: 07/23/1973
• Status: Expired due to Term

• Current Assignee: Halliburton Company
• Original Assignee: Edwin B. Neitzel, Marvin D. Gontarek
• Inventors: Neitzel, Edwin B., Gontarek, Marvin D.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Birmiel, H. A.
• Application Number:
  US05/381,812
• Time in Patent Office: 680 Days
• Field of Search: 340/7R,15.5MC,15.5CP,15.5GC
• US Class Current: 367/20
• CPC Class Codes: G01V 1/20 Arrangements of receiving elements, e.g. geophone pattern

Abstract

A system is disclosed wherein selections are available at a marine seismic survey boat which allows an operator to change the effective array length in integer multiples of the length of a unit array with array centers maintained constant while simultaneously introducing weighting which maintains constant the relative signal levels between channels.

Claims

1. Means for varying the effective seismic detector array length while maintaining constant the effective detector array spacing in a seismic surveying system where an array channel from each detector array in a seismic spread leads to a multi-channel recorder, comprising:

a. a plurality of multi-state input/output channel selectors, each connected at one input thereof to one of said array channels by means of first weighting means leading to first input terminals of said selectors, b. connections between pairs of said array channels from adjacent detector arrays each by means of pairs of second weighting means leading to second input terminals of said selectors, and c. means for selectively connecting inputs of said recorder to said first or said second output terminals of said selectors.

2. The combination set forth in claim 1 wherein said first weighting means and said second weighting means are of magnitude to maintain the same relative signal level applied to said recorder from said first output terminal as from second output terminal.

3. In a seismic surveying system where a spread a seismic arrays provide individual seismic signals, one from each array, for array channels leading to a recorder, the combination which comprises:

a plurality of multi choice selectors each connected at inputs thereof to a set of array channels numbered 1,2 . . . n, which lead from a set of correspondingly numbered arrays, wherein each consecutively numbered array in said set of arrays is contiguous in said spread with each numbered array adjacent to it, and wherein a consecutively numbered subset of the set 1, 2 . . . n connected to each of adjacent selectors differs in beginning and end numbers from those of the previous or following subset connected to the previous or following selector by one number;

an output channel leading from each said selector to said recorder; and

connections in each said selector to combine on each said output channel a summation of signals from said array channels in Number selectable from the number in said subsets down to single channel signals to vary the effective array length while maintaining constant the array spacing.

4. The combination set forth in claim 3 wherein said connections include weighting means of magnitude to maintain the same relative signal level applied to said recorder.

5. In a marine seismograph system where a plurality of traces are produced by energization of a multi-channel recorder, the combination which comprises:

a. a streamer to be pulled through the water along a seismic traverse having a plurality of like detector sections where each section contains a plurality of detectors whose output signals are combined for each section on array channels leading to said recorder individual to each section, b. a plurality of multistate input/output channel selectors, each having an output terminal connected to an input trace of said recorder and each connected at one input thereof to the array channel from one said section by means of first weighting means, c. a connection at each of the selectors between pairs of said array channels from adjacent detector sections each by means of a pair of second weighting means the junction between said pair of second weighting means leading to a second input terminal of the corresponding selector, and d. means for selectively connecting the output terminal of each selector to the first or second input terminal of said selector.

6. The combination set forth in claim 5 wherein said first weighting means and said second weighting means are of magnitude to maintain constant the relative levels of signals applied to said recording from said first and second input terminals.

7. The combination set forth in claim 5 wherein means are provided to signal any differences in setting of said selectors.

8. In a system where n seismic array channels transmit signals from a spread made up of contiguous end-to-end seismic arrays 1, 2 . . . n, the combination which comprises:

a set of n-m+1 selectors of m sections per selector, connections in said selectors to selectably combine on each selector output summations of signals from seismic array channels the selectable combinations on any given selector output comprising the weighted summations of sets of said array channels included within the series n-x;

n-x and n-x-1;

n-x, n-x-1 and n-x-2;

. . . ;

n-x, n-x-1, . . . , n-x- m+2 and n-x-m+1 where x is any non-negative integer not greater than n-m and each different value of x defines said series for a different selector.

9. In a system where n seismic array channels transmit signals from a spread of contiguous end-to-end seismic arrays 1, 2 . . . n, the combination which comprises:

a set of n-m+1 selectors of m sections per selector a plurality of couplings between said selectors each of said couplings comprising connections between one of said array channels and a set of selector sections consisting of section m of selector n-y, section m-1 of selector n-y-1, . . . section m-(m-1) of selector n- y-(m-1) where y is any integer greater than m-2 but not greater than n-m, and connections between adjacent array channels and adjacent selectors to selectably provide on each selector output summations of signals from seismic array channels the selectable combinations on any given selector output comprising the summations of sets of said array channels included within the series n-x;

n- x and n-x-1;

n-x, n-x-1 and n-x-2;

. . .;

n-x, n-x-1, . . . , n- x-(m-2) and n-x-(m-1) where x is any non-negative inteGer not greater than n-m each different value of x defining said series for a different selector and wherein each of said connections includes weighting means of magnitudes such that the signal level at the output of any selector in response to identical signals on all of said array channels is independent of the specific output summation selected.