CN102590861A - Seismic wave beam forming method based on receiving array - Google Patents

Abstract

The invention relates to a seismic wave beam forming method based on a receiving array. Aiming at a conventional controllable focus seismic data set U, a delaying parameter Tau is adopted to form a control parameter n with a wave beam; a directional seismic data set V1 is synthesized by utilizing a wave beam forming method; if the signal to noise ratio of the data set V1 meets the quality requirement of collected data, the process is finished; if the signal to noise ratio of the data set V1 is still lower, a secondary wave beam forming process is carried out on the data set V1 to obtain a directional seismic data set V2, and on the like, directional seismic wave data Vopt meeting the requirement of the signal to noise ratio is synthesized. Compared with the prior art, the seismic wave beam forming method has the advantages that: firstly, data collection can be finished by only using single controllable seismic source, the collection process is simple and the collection cost is far lower than that of an array seismic source; secondly, compared with a direction illumination collection technology based on the single seismic source, the capability of improving the signal to noise ratio is greatly improved; and thirdly, a seismic exploration depth can be greatly improved under the condition of not changing output force of the controllable seismic source, so that the seismic wave beam forming method is particularly suitable for a lamellar geologic body which has stronger background noises and is difficult to obtain the data with the high signal to noise ratio.

Description

Earthquake wave beam formation method based on receiving array

Technical field:

The present invention relates to a kind of disposal route of geophysical data, especially the preprocess method of vibroseis geological data.

Background technology:

Existing vibroseis method of seismic prospecting, since destructive to the nothing of environment, in seismic prospecting, receive all the more widely and paying close attention to.

CN1560650 discloses a kind of " phased earthquake controllable earthquake focus system ",

CN1560651 discloses a kind of " phased array method of seismic prospecting ",

CN101320095 discloses a kind of " single-seismic source directional lighting seismic signal synthesizing method ",

CN101339252 " based on the directional lighting method of seismic prospecting of single focus "; The subject matter that the vibroseis seismic prospecting exists is that ground unrest is strong a little less than the seismic source energy, and the signal to noise ratio (S/N ratio) that therefore receives data is lower, and depth of exploration is shallow.In order to improve the image data quality, can adopt wave beam formation method, form the directivity seismic event.Wave beam formation method can realize at the focus end, also can realize at receiving end.Ignoring under the noise situations, the two is of equal value.The wave beam formation method of source end is called phased focus method, and this method requires to use has the Seismic Source System of phase control function, and strict to the coherence request of each focus.

Summary of the invention:

The objective of the invention is to deficiency, a kind of earthquake wave beam formation method based on receiving array is provided to prior art.

Utilize wave beam formation method to synthesize directed seismic data, increase substantially purpose reflection horizon geological data signal to noise ratio (S/N ratio) or increase substantially the vibroseis seismic prospecting degree of depth.

Based on the earthquake wave beam formation method of receiving array, be to the many big guns vibroseis geological data that is total to offset distance, utilize beam-forming technology, adopt the time domain stacking method, in the synthetic directed seismic data of receiving end.Main thought is following: to conventional vibroseis earthquake data set U, use delay parameter τ, form controlled variable n with wave beam, utilize wave beam formation method to synthesize directed earthquake data set V ₁If data set V ₁Signal to noise ratio (S/N ratio) satisfy the image data quality requirements, processing finishes; If data set V ₁Signal to noise ratio (S/N ratio) still very low, to data set V ₁, do the secondary wave beam and form processing, can obtain directed earthquake data set V ₂The rest may be inferred ..., can synthesize and satisfy the directed seismic data V that signal to noise ratio (S/N ratio) requires _OptDirectionally the seismic wave direction is controlled by delay parameter.Rationally control directionally seismic wave direction, the reflection wave signal signal to noise ratio (S/N ratio) of objective body is significantly strengthened.Reaching obliquely to solution very noisy geologic province, the plastid exploration has outstanding substantive distinguishing features and obvious improvement.

The objective of the invention is to realize through following technical scheme:

Earthquake wave beam formation method based on receiving array comprises following order and step:

A, in survey area, design controllable focus seismic line, and offset distance observation procedure such as employing, promptly maximum, the minimum geophone offset of each shot point record remain unchanged, the recording channel number is constant, track pitch is constant;

B, each shot point displacement are the integral multiple N of track pitch, and might as well establish track pitch is Δ x, and then shotpoint spacing is N * Δ x;

C, on this survey line, move shot point, keep offset distance constant, obtain many big guns seismologic record U={R by setting shotpoint spacing ₁, R ₂..., R _i..., R _N, i is the shot point sequence number, R _iBe i big gun record, N is total big gun number, makes current accessible single shot record count n=N;

D, the many big guns seismologic record that will obtain divide into groups.Group technology is following, and establishing wave beam formation controlled variable is m, and m is taken as the odd number greater than 2 usually.Definition p sub-set U on record set U _i, U _I+1..., U _j, wherein So p=j-i+1.Arbitrary subclass U _w, represent a seismologic record to divide into groups, comprising with w shot point is adjacent m single shot point record, the i.e. U at center _w={ R _b, R _B+1..., R _w, R _W+1... R _e, at this moment

E, to the grouping of each seismographic record, adopt beam-forming technology, the directed seismographic record of a synthetic respectively big gun.Concrete grammar is following: with w shot point is example, selects data set U _w, can synthesize the directed seismologic record of w big gun.To U _wthe adjacent shot point record of M=e-b+1 uniformly-spaced time-delay, i.e. R successively _bTime-delay (b-w) τ, R _B+1Time-delay (b+1-w) τ ..., R _wTime-delay is 0, R _W+1Time-delay τ ..., R _eTime-delay (e-w) τ.In the above-mentioned delay operation, R _wRecord delay time before is equivalent to being recorded in the time orientation reach for negative; R _wRecord delay time afterwards is equivalent to after being recorded in time orientation, move for just.Might as well establish U _wThe new record collection that interior record time-delay back forms is u _w={ r _b, r _B+1..., r _w, r _W+1... r _e.With u _wInterior whole records are superimposed, and can obtain the directed seismologic record p of w big gun _w

F, employing step e can synthesize directed earthquake record set V ₁, V wherein ₁Contain n-(m-1) big gun data, be designated as V ₁={ p _j, p _J+1... .p _K-1, p _k, wherein

V ₁Be that a wave beam forms the directed earthquake record set that obtains, this data correspondence has the seismic wave field of directivity, and single wave beam formation method can be improved the geological data signal to noise ratio (S/N ratio); Data set V ₁If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, processing procedure finishes, otherwise continues execution in step g;

G, to U initialize again, make that initial value is V ₁To n initialize again, initial value equals n-(m-1);

H, U is regarded as conventional geological data; This data set is adopted above-mentioned d to f step; Do wave beam once more and form processing, the controlled variable m and the delay parameter τ of beam forming process employing this time can independently select in principle, handle identical parameter but advise using with a wave beam formation.Form through wave beam once more and to handle the earthquake data set that obtains and be designated as V ₂, being called the secondary wave beam and forming the seismologic record collection, this data signal to noise ratio (S/N ratio) forms data set V than the single wave beam ₁Further improve; Data set V ₂If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, processing procedure finishes, otherwise continues execution in step i;

I, to U initialize again, make that initial value is V ₂To n initialize again, initial value equals n-2 * (m-1);

J, U is regarded as conventional geological data; This data set is adopted above-mentioned d to f step; Do wave beam once more and form processing, the controlled variable m and the delay parameter τ of beam forming process employing this time can independently select in principle, handle identical parameter but advise using with a wave beam formation.Handle the earthquake data set that obtains through this wave beam formation and be designated as V ₃, being called the tertiary wave bundle and forming the seismologic record collection, this data signal to noise ratio (S/N ratio) forms data set V than the secondary wave beam ₂Further improve; Data set V ₃If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, processing procedure finishes, otherwise can continue to carry out four times, five times ... So that wave beam forms and handles more frequently, till the data signal to noise ratio (S/N ratio) has satisfied the exploration demand.

Beneficial effect: through test; It is stronger that earthquake wave beam formation method based on receiving array disclosed by the invention is suitable for ground unrest; Be difficult to obtain the seismic prospecting environment of high s/n ratio data; Compare with existing single focus, phased focus and conventional directional lighting seismic signal, improve more remarkable to the earthquake Signal-to-Noise based on the earthquake wave beam formation method of receiving array.Compare with phased focus method, the present invention has that the focus of needs number is few, and job costs are low, control simple advantage, and has overcome because the inconsistent phased earthquake effect degradation problem that causes of many vibration exciters.Compare with single focus, conventional directional lighting seismic method, the present invention improves obviously earthquake data quality, and the seismic exploration degree of depth significantly intentinonally.

The advantage of this method is three aspects.The one, only need to adopt single vibroseis to accomplish data acquisition, so gatherer process is simple, acquisition cost is technological far below the array focus; The 2nd, compare with directional lighting acquisition technique based on single focus, ability significantly improves aspect the signal to noise ratio (S/N ratio) improving; The 3rd, not changing under the vibroseis power output situation, can increase substantially the seismic prospecting degree of depth.It is stronger that the present invention is particularly useful for ground unrest, is difficult to obtain the stratiform underground medium situation of high s/n ratio data.This method is applicable to any vibroseis earthquake

Description of drawings:

Fig. 1 is a wave beam formation method of the earthquake synoptic diagram based on receiving array

Embodiment:

Based on the earthquake wave beam formation method of receiving array, be in the receiving end of seismic prospecting system application of beam formation method repeatedly, utilize the airspace filter means, extract destination layer reflection seismic waves signal.The seismic event main beam direction of gathering is by the delay parameter control of beam forming process each time.Rationally control directionally seismic wave direction, can make the reflection wave signal signal to noise ratio (S/N ratio) of objective body the strongest.

In the processing procedure of wave beam formation each time, the beam direction parameter can change, but in real process, same direction is adopted in suggestion, promptly adopts identical delay parameter.During each data acquisition, shotpoint spacing can be chosen according to predetermined level stack degree of covering, and shotpoint spacing is made as the integral multiple of track pitch in principle.

In the present embodiment with m=3, geophone offset=track pitch is the example explanation, and the secondary wave beam forms and is treated to the example explanation, but the parameter limit that not provided by instance based on the application of the earthquake wave beam formation method of receiving array.

Earthquake wave beam formation method based on receiving array comprises following order and step:

A, in survey area, design controllable focus seismic line, and offset distance observation procedure such as employing, promptly maximum, the minimum geophone offset of each shot point record remain unchanged, the recording channel number is constant, track pitch is constant;

B, each shot point displacement are the integral multiple N of track pitch, and might as well establish track pitch is Δ x, and then shotpoint spacing is N * Δ x;

C, on this survey line, move shot point, keep offset distance constant, obtain many big guns seismologic record U={R by setting shotpoint spacing ₁, R ₂..., R _i..., R _N, i is the shot point sequence number, R _iBe i big gun record, N is total big gun number, makes current accessible single shot record count n=N;

D, the many big guns seismologic record that will obtain divide into groups.Group technology is following, and establishing wave beam formation controlled variable is m, and m is taken as the odd number greater than 2 usually.Definition p sub-set U on record set U _i, U _I+1..., U _j, wherein

So p=j-i+1.Arbitrary subclass U _w, represent a seismologic record to divide into groups, comprising with w shot point is adjacent m single shot point record, the i.e. U at center _w={ R _b, R _B+1..., R _w, R _W+1... R _e, at this moment

E, to the grouping of each seismographic record, adopt beam-forming technology, the directed seismographic record of a synthetic respectively big gun.Concrete grammar is following: with w shot point is example, selects data set U _w, can synthesize the directed seismologic record of w big gun.To U _wthe adjacent shot point record of M=e-b+1 uniformly-spaced time-delay, i.e. R successively _bTime-delay (b-w) τ, R _B+1Time-delay (b+1-w) τ ..., R _wTime-delay is 0, R _W+1Time-delay τ ..., R _eTime-delay (e-w) τ.In the above-mentioned delay operation, R _wRecord delay time before is equivalent to being recorded in the time orientation reach for negative; R _wRecord delay time afterwards is equivalent to after being recorded in time orientation, move for just.Might as well establish U _wThe new record collection that interior record time-delay back forms is u _w={ r _b, r _B+1..., r _w, r _W+1... r _e.With u _wInterior whole records are superimposed, and can obtain the directed seismologic record p of w big gun _w

F, employing step e can synthesize directed earthquake record set V ₁, V wherein ₁Contain n-(m-1) big gun data, be designated as V ₁={ p _j, p _J+1... .p _K-1, p _k, wherein

V ₁Be that a wave beam forms the directed earthquake record set that obtains, this data correspondence has the seismic wave field of directivity, and single wave beam formation method can be improved the geological data signal to noise ratio (S/N ratio); As data set V ₁If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, continue execution in step g;

G, to U initialize again, make that initial value is V ₁To n initialize again, initial value equals n-(m-1);

H, U is regarded as conventional geological data; This data set is adopted above-mentioned d to f step; Do wave beam once more and form processing, the controlled variable m and the delay parameter τ of beam forming process employing this time can independently select in principle, handle identical parameter but advise using with a wave beam formation.Form through wave beam once more and to handle the earthquake data set that obtains and be designated as V ₂, being called the secondary wave beam and forming the seismologic record collection, this data signal to noise ratio (S/N ratio) forms data set V than the single wave beam ₁Further improve; If data set V ₂If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, processing procedure finishes, and the secondary wave beam formation processing of accomplishing this moment based on receiving array finishes.

I, wave beam form the selection of parameter method

Wave beam based on receiving array forms the delay parameter and the following relation of reception seismic event main beam direction existence that relates to

$\mathrm{\τ}=\frac{{d\mathrm{Sin}\mathrm{\θ}}_{\mathrm{Max}}}{v}$ (formula 1)

Shotpoint spacing d=N * Δ x wherein, v is the average velocity that covers medium on the objective body.

Order

β=-2 π f τ, "-" expression is delayed time by each single shot record of shot point order successively, and f represents the seismic event centre frequency.Adopt delay parameter τ, form through wave beam and handle, can obtain the seismic wave field direction factor

$F_a\left(\mathrm{\θ}\right)=\frac{f_a\left(\mathrm{\θ}\right)}{n}=\frac{1}{n}\frac{\mathrm{Sin}\frac{\mathrm{\ψ}}{2}}{\mathrm{Sin}\frac{\mathrm{\ψ}}{2}}=\frac{1}{n}\frac{\mathrm{Sin}\left[\frac{n}{2}(\mathrm{Kd}\mathrm{Sin}\mathrm{\θ}+\mathrm{\β})\right]}{\mathrm{Sin}\left[\frac{1}{2}(\mathrm{Kd}\mathrm{Sin}\mathrm{\θ}+\mathrm{\β})\right]}$ (formula 2)

Wherein θ is the normal direction angle of observed ray, F _a(θ) reflected seismic event field intensity Changing Pattern on the different directions, can know that by formula (1) and (2) the seismic event main beam direction does

θ _Max=arcsin (τ * v/d) (formula 3)

Claims (1)

1. the earthquake wave beam formation method based on receiving array is characterized in that, comprises following order and step:

A, in survey area, design controllable focus seismic line, employing waits the offset distance observation procedure, promptly maximum, the minimum geophone offset of each shot point record remain unchanged, the recording channel number is constant, track pitch is constant;

B, each shot point displacement are the integral multiple N of track pitch, and might as well establish track pitch is Δ x, and then shotpoint spacing is N * Δ x;

C, on this survey line, move shot point, keep offset distance constant, obtain many big guns seismologic record U={R by setting shotpoint spacing ₁, R ₂..., R _i..., R _N, i is the shot point sequence number, R _iBe i big gun record, N is total big gun number, makes current accessible single shot record count n=N;

D, the many big guns seismologic record that will obtain divide into groups: group technology is following, and establishing wave beam formation controlled variable is m, and m is taken as the odd number greater than 2 usually, definition p sub-set U on record set U _i, U _I+1..., U _j, wherein

So p=j-i+1; Arbitrary subclass U _w, represent a seismologic record to divide into groups, comprising with w shot point is adjacent m single shot point record, the i.e. U at center _w={ R _b, R _B+1..., R _w, R _W+1... R _e, at this moment

E, divide into groups, adopt beam-forming technology to each seismologic record, the directed seismologic record of a synthetic respectively big gun, concrete grammar is following: with w shot point is example, selection data set U _w, can synthesize the directed seismologic record of w big gun; To U _wthe adjacent shot point record of M=e-b+1 uniformly-spaced time-delay, i.e. R successively _bTime-delay (b-w) τ, R _B+1Time-delay (b+1-w) τ ..., R _wTime-delay is 0, R _W+1Time-delay τ ..., R _eTime-delay (e-w) τ, in the above-mentioned delay operation, R _wRecord delay time before is equivalent to being recorded in the time orientation reach for negative; R _wRecord delay time afterwards is equivalent to after being recorded in time orientation, move for just, might as well establish U _wThe new record collection that interior record time-delay back forms is u _w={ r _b, r _B+1..., r _w, r _W+1... r _e, with u _wInterior whole records are superimposed, and can obtain the directed seismologic record p of w big gun _w

F, employing step e can synthesize directed earthquake record set V ₁, V wherein ₁Contain n-(m-1) big gun data, be designated as V ₁={ p _j, p _J+1... .p _K-1, p _k, wherein

V ₁Be that a wave beam forms the directed earthquake record set that obtains, this data correspondence has the seismic wave field of directivity, and single wave beam formation method can be improved the geological data signal to noise ratio (S/N ratio); Data set V ₁If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, processing procedure finishes, otherwise continues execution in step g;

G, to U initialize again, make that initial value is V ₁To n initialize again, initial value equals n-(m-1);

H, U is regarded as conventional geological data; This data set is adopted above-mentioned d to f step; Do wave beam once more and form processing, the controlled variable m and the delay parameter τ of beam forming process employing this time can independently select in principle, handle identical parameter but advise using with a wave beam formation; Form through wave beam once more and to handle the earthquake data set that obtains and be designated as V ₂, being called the secondary wave beam and forming the seismologic record collection, this data signal to noise ratio (S/N ratio) forms data set V than the single wave beam ₁Further improve; Data set V ₂If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, processing procedure finishes, otherwise continues execution in step i;

I, to U initialize again, make that initial value is V ₂To n initialize again, initial value equals n-2 * (m-1);

J, U is regarded as conventional geological data; This data set is adopted above-mentioned d to f step; Do wave beam once more and form processing, the controlled variable m and the delay parameter τ of beam forming process employing this time can independently select in principle, handle identical parameter but advise using with a wave beam formation.Handle the earthquake data set that obtains through this wave beam formation and be designated as V ₃, being called the tertiary wave bundle and forming the seismologic record collection, this data signal to noise ratio (S/N ratio) forms data set V than the secondary wave beam ₂Further improve; Data set V ₃If corresponding signal to noise ratio (S/N ratio) is seismic exploration image data quality requirements contentedly, processing procedure finishes, otherwise can continue to carry out four times, five times ... So that wave beam forms and handles more frequently, till the data signal to noise ratio (S/N ratio) has satisfied the exploration demand.

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