Directional filtering of seismic data

Claim 2

In a method of processing a set of signals taken from a geophone array positioned above a seismically reflective subsurface structure, the steps comprising: selecting a batch of input signAls, said batch of input signals being a subset of said set of signals; focusing said batch of input signals so that substantially all of the signal energy of a plane wave event present in said batch of signals will be in phase at some angle phi , said angle being related to the angle at which said plane wave event emerges from said subsurface structure at said geophone array; generating a batch of output signals, each of said output signals being associated with a particular direction of arrival of seismic waves at said geophone array and comprising the sum of signal energy focused from plane wave events arriving from said direction, whereby said angle phi is indicated by a relatively large concentration of signal energy in one of said output signals.

Claim 3

The method of claim 1 wherein said subset of seismic signals is associated with geophones in said geophone array lying in a substantially straight line.

Claim 4

The method of claim 1 further characterized by the steps of: modifying said first batch of input signals to form a second batch of input signals, said second batch of input signals consisting of the outputs of some predetermined subset of said set of seismic signals, a substantial number of whose elements overlap said first subset; and repeating the method until all elements of said set of seismic signals have been processed a substantially equal number of times.

Claim 5

The method of claim 1 further characterized by a step of summing said batch of output signals to form a non-migrated composited output.

Claim 6

The method of claim 4 further characterized by the step of displaying said summed batch of output signals.

Claim 7

The method of claim 3 further characterized by the steps of: generating a batch of output signals for each set of input signals, each output signal of said batch of output signals being related to an angle, at which said batch of seismic signals can be found; and displaying said batches of output signals.

Claim 8

The method of claim 3 further characterized by the steps of: projecting each signal of each of said batch of output signals downwardly from their respective originating points at an angle, Alpha arcsin displaying said projected signals.

Claim 9

In a method of processing seismic data traces obtained from seismic receiving stations located above seismically reflective subterranean structures, the steps comprising: correcting a selected batch of such seismic data traces to provide move-out corrected traces; focusing the data contained in the batch of move-out corrected traces by producing quantities related to acoustic waves that propagate through a homogenous medium from points dispersed along a curve in a 1 to 1 mapping of the disposition of the receiving stations from which the seismic data traces were obtained; dividing the focal plane of said curve into a plurality of sectors so that each sector is related to a selected volume within the subsurface region from which the seismic data traces were obtained; summing focused data that appears in each of said sectors by producing a quantity related to the sum of acoustic energy that propagates from the points along said curve to each sector; and producing output signals related to the quantity summed in each of said sectors so that each output signal is related to seismic energy that is reflected along a ray path extending from the center of the array of seismic receiving stations to a selected volume within the subsurface region.

Claim 10

In a method of processing seismic data traces obtained from seismic receiving stations located above seismically reflective subterranean structures, the steps comprising: correcting a selected batch of such seismic data traces to provide move-out corrected traces; focusing the data contained in the batch of move-out corrected traces by producing quantities related to acoustic waves that propagate through a homogenous medium from points dispersed along a curve in a 1 to 1 mapping of the disposition of the receiving stations from which the seismic data traces were obtained; dividing the focal plane of said curve into a plurality of sectors so that each sector is related to a selected volume within the subsurface region from which the seismic data traces were obtained; summing focused data that appears in each of said sectors by producing a quantity related to the sum of acoustic energy that propagates from the points along said curve to each sector; and producing output signals related to the quantity summed in each of said sectors so that each output signal is related to seismic energy that is reflected along a ray path extending from the center of the array of seismic receiving stations to a selected volume within the subsurface region.

Claim 15

The system of claim 10 wherein said data modifying means includes means for producing a visible display of said physical quantities with said amplitudes with time appearing along time axes that are inclined relative to each other at the angles along which said elastic waves are focused by said transmissions and receptions.

Claim 16

The system of claim 10 wherein said data modifying means includes means for summing a plurality of batches of said physical quantities corresponding to appearances of said transmitted and received elastic waves.

Claim 17

The system of claim 10 wherein said means for producing physical quantities and said data modifying means are inclusive of digital computer means.