CN105572735A - Method and device for improving imaging precision of prestack depth offset - Google Patents
Method and device for improving imaging precision of prestack depth offset Download PDFInfo
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Abstract
The invention provides a method and device for improving the imaging precision of prestack depth offset. The method comprises the following steps that epicenter data and prestack shot data are read; the epicenter data and the prestack shot data are processed to obtain a combined imaging result; multiples in the prestack shot data is carried out to obtain prediction data of surface multiples; the epicenter data and the prediction data are processed to obtain interference noise; a combined prestack depth offset result is subtracted from the interference noise by matching to obtain a combined prestack depth offset result after attenuation of the interference noise; and the combined prestack depth offset result after attenuation of the interference noise is displayed as an earthquake profile image. According to the method and device provided by the invention, the interference noise generated in the offset process is attenuated, and the imaging precision is improved.
Description
Technical field
The application relates to the pre-stack depth migration imaging technical field in petroleum prospecting reflection wave seismic data process process, particularly a kind of method and device improving pre-stack depth migration imaging precision.
Background technology
Pre-stack depth migration is a new technology in seismic data process, and this technology can revise the subsurface image distortion that steep dip stratum and velocity variations produce, can by complex structure or the larger correct imaging of seismic data of lateral variation in velocity.Most pre-stack depth migration imaging only reflects hypothesis once based on all scattared energies at subsurface interface, and in fact, sound wave is having part generation secondary or multiple reflections in the return course of earth's surface, forms multiple reflection.Multiple reflection is both advantageous and disadvantageous in oceanic earthquake data, and on the one hand, when complicated underground structure, the primary reflection of some regions is difficult to illumination, and multiple reflection can be thrown light on by multiple reflections, can improve the precision of imaging; On the other hand, when carrying out primary reflection and combining pre-stack depth migration imaging with multiple reflection, the interference noise produced in imaging process by source wavelet and multiple reflection can have a strong impact on imaging precision.
In recent years, many experts and scholars had done a series of research in raising pre-stack depth migration imaging precision.Document [1] and document [2] are respectively based on full acoustic wave and one-way wave migration operator, to the record wave field of focus be included as down-going wave fields, multiple reflection realizes the joint imaging of primary reflection and multiple reflection as upstream wave field, but the interference noise that source wavelet and multiple reflection produce in dependent imaging process have impact on image quality; Document [3] adopts first independent to primary reflection and multiple reflection imaging respectively, then carries out joint imaging by the method for coupling addition, image quality be improved significantly, but still cannot eliminate the interference illusion noise that source wavelet and multiple reflection produce.Document [4], based on the method for least square inverse time multiple reflection skew, to be decayed interference noise, but successive ignition computing is needed a large amount of computer resources and time by successive ignition computing.
[1]WangYB,ChangXandHuH.Simultaneousreversetimemigrationofprimariesandfree-surfacerelatedmultipleswithoutmultipleprediction.Geophysics,2014,79(1):S1-S9；
[2] Guo Shujuan, Li Zhenchun, Tong Zhaoqi etc. the big gun offset method based on broad sense realizes earth's surface multiple reflection and primary reflection joint imaging. Chinese Journal of Geophysics, 2011,54 (4): 1098-1105;
[3] Ye Yueming, Zhao Changlei, Zhuan Xijin etc. based on the earth's surface related multiple imaging of one-way wave migration operator, Chinese Journal of Geophysics .2014,57 (4): 1241-1250;
[4]ZhangDLandSchusterGT.Least-squaresreversetimemigrationofmultiples.Geophysics,2014,79(1):S11-S21.
Summary of the invention
The object of the application is that decay primary reflection combines the interference noise produced by source wavelet and multiple reflection in pre-stack depth migration imaging with multiple reflection, improves primary reflection combines pre-stack depth migration imaging precision with multiple reflection.
This application provides a kind of method improving pre-stack depth migration imaging precision, the method comprises the following steps:
Read source data and prestack shot gather data, described source data comprises source wavelet, and described prestack shot gather data comprises primary reflection and multiple reflection;
Pre-stack depth migration process is carried out to source data and prestack shot gather data, obtains primary reflection and combine pre-stack depth migration result with multiple reflection;
Free Surface related multiple Forecasting Methodology is adopted to the multiple reflection in prestack shot gather data, obtains the predicted data of surface-related multiple;
Pre-stack depth migration process is carried out to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces;
The described associating pre-stack depth migration result obtained and the described interference noise obtained are passed through to mate, subtract each other, the primary reflection obtained after decay interference noise combines pre-stack depth migration result with multiple reflection;
Primary reflection after decay interference noise is combined pre-stack depth migration result with multiple reflection and is shown as seismic section image.
The application also provides a kind of device improving pre-stack depth migration imaging precision, this device comprises data read module, associating pre-stack depth migration processing module, Free Surface multiple reflection prediction module, interference noise generation module, interference noise cancellation module, image-forming module, wherein:
Described data read module, for reading source data and prestack shot gather data, described source data comprises source wavelet, and described prestack shot gather data comprises primary reflection and multiple reflection;
Described associating pre-stack depth migration processing module, for carrying out pre-stack depth migration process to source data and prestack shot gather data, obtaining primary reflection and combining pre-stack depth migration result with multiple reflection;
Described Free Surface multiple reflection prediction module, obtains the predicted data of surface-related multiple for adopting Free Surface related multiple Forecasting Methodology to the multiple reflection in prestack shot gather data;
Described interference noise generation module, for carrying out pre-stack depth migration process to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces;
Described interference noise cancellation module, for primary reflection being combined pre-stack depth migration result with multiple reflection and source wavelet subtracts each other by mating with the interference noise that the surface-related multiple of prediction produces, the primary reflection after the interference noise that obtains decaying combines pre-stack depth migration result with multiple reflection;
Described image-forming module, is shown as seismic section image for the primary reflection after decay interference noise is combined pre-stack depth migration result with multiple reflection.
A kind of method and device improving pre-stack depth migration imaging precision that the embodiment of the present application provides, carry out while primary reflection carries out associating pre-stack depth migration imaging with multiple reflection, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces, associating pre-stack depth migration result carried out mating, subtracting each other with the interference noise of generation by the method for Least squares matching again, the primary reflection finally obtained after decay interference noise combines pre-stack depth migration result with multiple reflection.The application does not need successive ignition computing to interaction noise of decaying, there is higher efficiency and practicality, utilize mate the method for subtracting each other by interaction noise from primary reflection to combine pre-stack depth migration result with multiple reflection deduct can improve imaging precision while there is stronger guarantor's width.
Accompanying drawing explanation
Fig. 1 is a kind of process flow diagram improving the method for pre-stack depth migration imaging precision that the application provides;
Fig. 2 is a kind of schematic diagram improving the method for pre-stack depth migration imaging precision that the application provides;
Fig. 3 is a kind of modular structure schematic diagram improving the device of pre-stack depth migration imaging precision that the application provides;
Fig. 4 is that a kind of that the application provides improves the structural representation of combining pre-stack depth migration processing module in the device of pre-stack depth migration imaging precision;
Fig. 5 is a kind of structural representation improving interference noise generation module in the device of pre-stack depth migration imaging precision that the application provides;
Fig. 6 is a kind of structural representation improving interference noise cancellation module in the device of pre-stack depth migration imaging precision that the application provides;
Fig. 7 is F3/B3 rate pattern schematic diagram;
Fig. 8 (a) is that the primary reflection of all big guns combines pre-stack depth migration imaging result schematic diagram with multiple reflection;
Fig. 8 (b) is the interference noise imaging results schematic diagram that the source wavelet of all big guns and the surface-related multiple of prediction produce;
Fig. 8 (c) is that after decay interference noise, the primary reflection of all big guns combines pre-stack depth migration imaging result schematic diagram with multiple reflection;
Fig. 8 (d) is the primary reflection pre-stack depth migration imaging result schematic diagram of all big guns;
Fig. 9 is real data rate pattern schematic diagram;
Figure 10 (a) is that the primary reflection of all big guns combines pre-stack depth migration imaging result schematic diagram with multiple reflection;
Figure 10 (b) is the interference noise imaging results schematic diagram that the source wavelet of all big guns and the surface-related multiple of prediction produce;
Figure 10 (c) is that after decay interference noise, the primary reflection of all big guns combines pre-stack depth migration imaging result schematic diagram with multiple reflection;
Figure 10 (d) is the primary reflection pre-stack depth migration imaging result schematic diagram of all big guns.
Embodiment
Technical scheme in the application is understood better in order to make those skilled in the art person, below in conjunction with the accompanying drawing in the embodiment of the present application, technical scheme in the embodiment of the present application is clearly and completely described, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiments.Based on the embodiment in the application, those of ordinary skill in the art are not making other embodiments all obtained under creative work prerequisite, all should belong to the scope of the application's protection.
The application provides a kind of method improving pre-stack depth migration imaging precision.Fig. 1 is a kind of process flow diagram improving the method for pre-stack depth migration imaging precision described in the application.As shown in Figure 1, described method comprises following treatment step:
S1: read source data and prestack shot gather data, described source data comprises source wavelet, and described prestack shot gather data comprises primary reflection and multiple reflection.
Above-mentioned source wavelet, primary reflection and multiple reflection use W (x, z, ω), P (x, z respectively, ω) represent with M (x, z, ω), wherein multiple reflection M (x, z, ω) comprise the multiple reflection of different rank, launch to be expressed as:
M(x,z,ω)＝M
1(x,z,ω)+M
2(x,z,ω)+…+M
N(x,z,ω)
Wherein, x is the horizontal direction coordinate in rectangular coordinate system in space, and z is depth direction coordinate, and ω is circular frequency.
Fig. 2 is described a kind of schematic diagram improving the method for pre-stack depth migration imaging precision.As shown in Figure 2, wherein W is focal point, and source wavelet, at X place, underground, first reflection occurs, and P is the acceptance point receiving primary event wave field, and primary event wave field is reflected back toward underground again, at X after earth's surface is received
1place produces second time reflection wave, and second time reflection wave returns to earth's surface at M
1place forms single order multiple reflection, and form a series of multiple reflection similarly, maximum order is N rank multiple reflections.According to the difference of the direction of propagation, primary reflection and multiple reflection are divided into again upstream wave field and down-going wave fields, and as shown in Figure 2, what propagate along first reflection point X to the acceptance point P of primary event wave field is exactly the upstream wave field of primary reflection, uses P
b(x, z, ω) represents; Along the acceptance point P of primary event wave field to second time reflection spot X
1what propagate is exactly the down-going wave fields of primary reflection, uses P
f(x, z, ω) represents.Similarly, the upstream wave field of multiple reflection and down-going wave fields use M respectively
b(x, z, ω) and M
f(x, z, ω) represents.
S2: carry out pre-stack depth migration process to source data and prestack shot gather data, obtains primary reflection and combines pre-stack depth migration result with multiple reflection.
As shown in Figure 2, by the primary reflection downward continuation that the source wavelet information at focal point W place and P point receive, can to the imaging of X point based on catoptric imaging condition; In like manner, by the primary reflection of P point and M
1the single order multiple reflection that point receives respectively downward continuation, and apply image-forming condition can to X
1point imaging.M herein
1the single order multiple reflection that point receives is that the primary reflection of P point is propagated downwards through X
1the wave field that point reflection is returned, then the primary reflection that P point receives can regard M as
1the plan focus of the single order multiple reflection of point; In like manner, by M
1the single order multiple reflection that point receives regards M as
2the plan focus of the second-order multiples that point receives, simultaneously by M
1the single order multiple reflection of point and M
2the second-order multiples downward continuation of point, application image-forming condition can to X
2point imaging; By that analogy, intend source wavefield information as long as corresponding and be included in the down-going wave fields of downward continuation, the multiple reflection of arbitrary order can imaging.
Therefore, the application can as down-going wave fields using source wavelet and the while of comprising the prestack shot gather data of primary reflection and multiple reflection, to the prestack shot gather data of primary reflection and multiple reflection be comprised as upstream wave field, then for the N rank multiple reflection received in wave field record, its source wavefield, namely N-1 rank multiple reflection can be included in the down-going wave fields be made up of source wavelet and prestack shot gather data, utilize the pre-stack depth migration imaging that paired N-1 rank multiple reflection seismic source information and N rank multiple reflection receiving record just can realize N rank multiple reflection, thus primary reflection and multiple reflection associating pre-stack depth migration imaging can be realized based on the pre-stack depth migration operator of wave equation, concrete outcome can be expressed as:
Wherein, img
pm(x, z) be that primary reflection combines pre-stack depth migration result with multiple reflection, ω min and ω max is minimum and maximum frequency respectively, subscript F represents down-going wave fields, subscript B represents upstream wave field, I part is primary reflection with same order multiple reflection is not to the true imaging of underground structure, and II part is the interference noise because dependent imaging between source wavelet and multiple reflection produces, specifically as shown in Figure 2.A in Fig. 2
1point is by regarding source wavelet as M mistakenly
1the plan focus of the single order multiple reflection that point receives, by source wavelet and single order multiple reflection downward continuation, the illusion that application image-forming condition obtains; In like manner, A
2point is by regarding source wavelet as M mistakenly
2the plan focus of the second-order multiples that point receives, by source wavelet and second-order multiples downward continuation, the illusion that application image-forming condition obtains, the interference noise that obtains of II part due to the energy level of energy level and I part true imaging close, therefore can the precision of severe jamming imaging, the relevant noise that III part is primary reflection, produce between multiple reflection, this part is produced by the multiple reflection of more high-order, therefore noise energy is more weak, so very little on the impact of imaging precision, IV part is reasons for its use noise, can not have a strong impact on the quality of true imaging equally.
S3: Free Surface related multiple Forecasting Methodology is adopted to the multiple reflection in prestack shot gather data, obtains the predicted data of surface-related multiple.
Said method is computing method well known to those skilled in the art, will repeat no more herein, the predicted data MP (x of the surface-related multiple calculated, z, ω) represent, MP (x, z, ω) comprise the Free Surface related multiple of different rank equally, launch to be expressed as:
MP(x,z,ω)＝MP
1(x,z,ω)+MP
2(x,z,ω)+…+MP
N(x,z,ω)。
Wherein, x is the horizontal direction coordinate in rectangular coordinate system in space, and z is depth direction coordinate, and ω is circular frequency.
S4: pre-stack depth migration process is carried out to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces.
In order to the interference noise that between source wavelet and multiple reflection, dependent imaging produces of effectively decaying, first need the interference noise obtaining separately predicting, embodiment is:
Using source wavelet as down-going wave fields;
Using the predicted data of surface-related multiple as upstream wave field;
Pre-stack depth migration operator based on wave equation carries out pre-stack depth migration process to down-going wave fields and upstream wave field, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces, and concrete outcome can be expressed as:
Wherein, img
m(x, z) is the interference noise that the predicted data of source wavelet and surface-related multiple produces, and subscript B represents upstream wave field.
S5: by the associating pre-stack depth migration result obtained in S2 and the interference noise obtained in S4 by mating, subtracting each other, the primary reflection obtained after decay interference noise combines pre-stack depth migration result with multiple reflection.
Owing to predicting that the interference noise obtained exists difference in energy level in the associating pre-stack depth migration result that obtains actual in step S2 and step S4, if directly carry out subtracting each other, the interference noise that between source wavelet and multiple reflection, dependent imaging produces of can not effectively decaying, therefore needed to carry out matching treatment to both before subtracting each other.A preferred version of the application's embodiment adopts the method for Least squares matching to try to achieve matching attribute, making in step S2 the actual associating pre-stack depth migration result obtained and predict in step S4 that the interference noise obtained mates in energy level, the primary reflection after the decay interference noise finally obtained is combined pre-stack depth migration result and can be expressed as with multiple reflection:
Wherein, img (x, z) be decay interference noise after primary reflection combine pre-stack depth migration result with multiple reflection, a (x, n) is matching attribute, and N is the length of signal, matching attribute is determined by Toeplitz matrix, can by Levinson rapidly predication method be solved to:
Wherein, K is the length of matching attribute, K<N, ψ
mm(x, z) predicts the interference noise img obtained
mthe auto-correlation of (x, z), ψ
pmm(x, z) is the actual associating pre-stack depth migration result img obtained
pmthe interference noise img that (x, z) obtains with prediction
mthe cross-correlation of (x, z), specifically can be expressed as:
Primary reflection after the decay interference noise finally obtained and multiple reflection combine that pre-stack depth migration result is same can be expressed as:
Wherein, I part is primary reflection with not same order multiple reflection to the true imaging of underground structure, the relevant noise that III part is primary reflection, produce between multiple reflection, IV part is reasons for its use noise, and the interference noise that between the source wavelet have the greatest impact to imaging results and multiple reflection, dependent imaging produces is eliminated.Meanwhile, the amplitude of true imaging part is not affected, and has stronger guarantor's width.
S6: the primary reflection after decay interference noise is combined pre-stack depth migration result with multiple reflection and is shown as seismic section image.
In practical operation, above-mentioned S1-S6 six steps are all done by big gun, for finally obtaining the section image at the entirely end, need to superpose the imaging results of all big guns.
The application also provides a kind of device improving pre-stack depth migration imaging precision, and Fig. 3 is the modular structure schematic diagram of the device of described raising pre-stack depth migration imaging precision.As shown in Figure 3, this device comprises data read module 1, associating pre-stack depth migration processing module 2, Free Surface multiple reflection prediction module 3, interference noise generation module 4, interference noise cancellation module 5, image-forming module 6, wherein:
Described data read module 1, for reading source data and prestack shot gather data, described source data comprises source wavelet, and described prestack shot gather data comprises primary reflection and multiple reflection;
Described associating pre-stack depth migration processing module 2, for carrying out pre-stack depth migration process to source data and prestack shot gather data, obtaining primary reflection and combining pre-stack depth migration result with multiple reflection;
Described Free Surface multiple reflection prediction module 3, obtains the predicted data of surface-related multiple for adopting Free Surface related multiple Forecasting Methodology to the multiple reflection in prestack shot gather data;
Described interference noise generation module 4, for carrying out pre-stack depth migration process to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces;
Described interference noise cancellation module 5, for primary reflection being combined pre-stack depth migration result with multiple reflection and source wavelet subtracts each other by mating with the interference noise that the surface-related multiple of prediction produces, the primary reflection after the interference noise that obtains decaying combines pre-stack depth migration result with multiple reflection;
Described image-forming module 6, is shown as seismic section image for the primary reflection after decay interference noise is combined pre-stack depth migration result with multiple reflection.
Fig. 4 is the structural representation of described associating pre-stack depth migration processing module 2.As shown in Figure 4, described associating pre-stack depth migration processing module 2 specifically comprises: down-going wave fields processing module 201, upstream wave field processing module 202, pre-stack depth migration operator module 203, wherein:
Described down-going wave fields processing module 201, for being set to down-going wave fields by source wavelet and prestack shot gather data simultaneously;
Described upstream wave field processing module 202, for being set to upstream wave field by prestack shot gather data;
Described pre-stack depth migration operator module 203, for carrying out pre-stack depth migration process to down-going wave fields and upstream wave field based on the pre-stack depth migration operator of wave equation, obtaining primary reflection and combining pre-stack depth migration result with multiple reflection.
Fig. 5 is the structural representation of described interference noise generation module 4.As shown in Figure 5, described interference noise generation module 4 specifically comprises: down-going wave fields processing module 401, upstream wave field processing module 402, pre-stack depth migration operator module 403, wherein:
Described down-going wave fields processing module 401, for being set to down-going wave fields by source wavelet;
Described upstream wave field processing module 402, for being set to upstream wave field by the predicted data of surface-related multiple;
Described pre-stack depth migration operator module 403, for carrying out pre-stack depth migration process, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces to down-going wave fields and upstream wave field based on the pre-stack depth migration operator of wave equation.
Fig. 6 is the structural representation of described interference noise cancellation module 5.As shown in Figure 6, described interference noise cancellation module 5 specifically comprises matching module 501 and subtraction module 502, wherein:
Described matching module 501, the interference noise that the surface-related multiple for primary reflection is combined pre-stack depth migration result and source wavelet and prediction with multiple reflection produces carries out Least squares matching;
Described subtraction module 502, for being undertaken subtracting each other process by the result after coupling.
The modules described in a kind of device improving pre-stack depth migration imaging precision that the application provides, specifically can be realized by computer chip or entity, or be realized by the product with certain function.
For convenience of description, each module is divided into describe respectively with function when describing above device.Certainly, the function of each module can be realized in same or multiple software and/or hardware when implementing the application.
In order to verify feasibility and the validity of the embodiment of the present application method and apparatus, set forth by two embodiments below.
Embodiment 1 surveys underground three interval velocity model, and Fig. 7 is F3/B3 rate pattern schematic diagram, surveys this F3/B3 rate pattern according to above-mentioned technical scheme:
First by big gun, pre-stack depth migration process is carried out to source data and prestack shot gather data, obtain primary reflection and combine pre-stack depth migration result with multiple reflection, again by superimposed for the pre-stack depth migration result of all big guns, obtain the imaging results as shown in Fig. 8 (a) by imaging device, from Fig. 8 (a), arrow indication can see the interference noise produced by dependent imaging between source wavelet and multiple reflection.
Then by big gun, Free Surface related multiple Forecasting Methodology is adopted to the multiple reflection in prestack shot gather data, obtain the predicted data of surface-related multiple, again pre-stack depth migration process is carried out to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces, obtains the imaging results as shown in Fig. 8 (b) by imaging device after the interference noise produced by all big guns is superimposed.
The result of Fig. 8 (a) and Fig. 8 (b) subtracted each other after Least squares matching, the primary reflection obtained after the decay interference noise as shown in Fig. 8 (c) combines pre-stack depth migration imaging result with multiple reflection.Can be found out by comparison diagram 8 (a) and Fig. 8 (c), the interference noise produced by dependent imaging between source wavelet and multiple reflection obtains effective decay.Fig. 8 (d) is the result only adopting primary reflection to carry out pre-stack depth migration imaging, although only adopt primary reflection to carry out pre-stack depth migration can not produce the interference noise produced by dependent imaging between source wavelet and multiple reflection, but the beneficial characteristics of multiple reflection imaging equally also cannot be utilized to obtain more complicated ground bottom structure, can be found out by the arrow indication place of comparison diagram 8 (c) and Fig. 8 (d), the imaging results utilizing technical scheme to obtain not only eliminates the interference noise that between source wavelet and multiple reflection, dependent imaging produces, also there is wider areas imaging and more balanced imaging configuration simultaneously, significantly improve the precision of imaging.
Embodiment 2 surveys real data rate pattern, and totally 300 roads receive, track pitch 12.5 meters, and 6 seconds writing times, Fig. 9 is real data rate pattern schematic diagram, surveys this real data rate pattern according to above-mentioned technical scheme:
First by big gun, pre-stack depth migration process is carried out to source data and prestack shot gather data, obtain primary reflection and combine pre-stack depth migration result with multiple reflection, again by superimposed for the pre-stack depth migration result of all big guns, obtain the imaging results as shown in Figure 10 (a) by imaging device, from Figure 10 (a), the interference noise produced by dependent imaging between source wavelet and multiple reflection in rectangle frame, can be seen.
Then by big gun, Free Surface related multiple Forecasting Methodology is adopted to the multiple reflection in prestack shot gather data, obtain the predicted data of surface-related multiple, again pre-stack depth migration process is carried out to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces, obtains the imaging results as shown in Figure 10 (b) by imaging device after the interference noise produced by all big guns is superimposed.
The result of Figure 10 (a) and Figure 10 (b) subtracted each other after Least squares matching, the primary reflection obtained after the decay interference noise as shown in Figure 10 (c) combines pre-stack depth migration imaging result with multiple reflection.Can be found out by contrast Figure 10 (a) and Figure 10 (c), the interference noise produced by dependent imaging between source wavelet and multiple reflection obtains effective decay.Figure 10 (d) is the result only adopting primary reflection to carry out pre-stack depth migration imaging, although only adopt primary reflection to carry out pre-stack depth migration can not produce the interference noise produced by dependent imaging between source wavelet and multiple reflection, but the beneficial characteristics of multiple reflection imaging equally also cannot be utilized to obtain more complicated ground bottom structure, can be found out by contrast Figure 10 (c) and Figure 10 (d), the imaging results utilizing technical scheme to obtain not only eliminates the interference noise that between source wavelet and multiple reflection, dependent imaging produces, there is higher vertical resolution and illumination harmony simultaneously, especially the imaging of arrow indication destination layer is greatly improved, continuity strengthens.
As seen through the above description of the embodiments, those skilled in the art can be well understood to the mode that the application can add required general hardware platform by software and realizes.Based on such understanding, the technical scheme of the application can embody with the form of software product the part that prior art contributes in essence in other words.This computer software product can be stored in storage medium, as ROM/RAM, magnetic disc, CD etc., comprising some instructions in order to make a computer equipment (can be personal computer, server, or the network equipment etc.) perform the method described in some part of each embodiment of the application or embodiment.
Claims (13)
1. improve a method for pre-stack depth migration imaging precision, it is characterized in that, said method comprising the steps of:
Read source data and prestack shot gather data, described source data comprises source wavelet, and described prestack shot gather data comprises primary reflection and multiple reflection;
Pre-stack depth migration process is carried out to source data and prestack shot gather data, obtains primary reflection and combine pre-stack depth migration result with multiple reflection;
Free Surface related multiple Forecasting Methodology is adopted to the multiple reflection in prestack shot gather data, obtains the predicted data of surface-related multiple;
Pre-stack depth migration process is carried out to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces;
The described associating pre-stack depth migration result obtained and the described interference noise obtained are passed through to mate, subtract each other, the primary reflection obtained after decay interference noise combines pre-stack depth migration result with multiple reflection;
Primary reflection after decay interference noise is combined pre-stack depth migration result with multiple reflection and is shown as seismic section image.
2. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 1, it is characterized in that, described source wavelet, primary reflection and multiple reflection use W (x respectively, z, ω, P (x, z, ω) and M (x, z, ω) represent, wherein multiple reflection M (x, z, ω) comprise the multiple reflection of different rank, launch to be expressed as:
M(x,z,ω)＝M
1(x,z,ω)+M
2(x,z,ω)+…+M
N(x,z,ω)
Wherein, x is the horizontal direction coordinate in rectangular coordinate system in space, and z is depth direction coordinate, and ω is circular frequency.
3. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 1, it is characterized in that, described pre-stack depth migration process is carried out to source data and prestack shot gather data, obtains primary reflection and combine pre-stack depth migration result with multiple reflection and specifically comprise following treatment step:
Using source wavelet and prestack shot gather data simultaneously as down-going wave fields;
Using prestack shot gather data as upstream wave field;
Pre-stack depth migration operator based on wave equation carries out pre-stack depth migration process to down-going wave fields and upstream wave field, obtains primary reflection and combines pre-stack depth migration result with multiple reflection.
4. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 3, is characterized in that, described primary reflection is combined pre-stack depth migration result and is with multiple reflection:
Wherein, img
pm(x, z) be that primary reflection combines pre-stack depth migration result with multiple reflection, ω min and ω max is minimum and maximum frequency respectively, subscript F represents down-going wave fields, subscript B represents upstream wave field, and I part is primary reflection with same order multiple reflection is not to the true imaging of underground structure, and II part is the interference noise because dependent imaging between source wavelet and multiple reflection produces, the relevant noise that III part is primary reflection, produce between multiple reflection, IV part is reasons for its use noise.
5. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 1, it is characterized in that, described Free Surface related multiple predicted data MP (x, z, ω) represent, MP (x, z, ω) comprise the Free Surface related multiple of different rank, launch to be expressed as:
MP(x,z,ω)＝MP
1(x,z,ω)+MP
2(x,z,ω)+…+MP
N(x,z,ω)。
6. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 1, it is characterized in that, described carries out pre-stack depth migration process to the predicted data of source data and surface-related multiple, and the interference noise that the surface-related multiple obtaining source wavelet and prediction produces comprises the following steps:
Using source wavelet as down-going wave fields;
Using the predicted data of surface-related multiple as upstream wave field;
Pre-stack depth migration operator based on wave equation carries out pre-stack depth migration process to down-going wave fields and upstream wave field, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces.
7. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 6, is characterized in that, the interference noise that the predicted data of described source wavelet and surface-related multiple produces is:
Wherein, img
m(x, z) is the interference noise that the predicted data of source wavelet and surface-related multiple produces, and subscript B represents upstream wave field.
8. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 1, is characterized in that, described coupling can realize by the method for Least squares matching.
9. a kind of method improving pre-stack depth migration imaging precision as claimed in claim 1, is characterized in that, the primary reflection after described decay interference noise is combined pre-stack depth migration result and is with multiple reflection:
Wherein, I part is primary reflection with not same order multiple reflection to the true imaging of underground structure, and III part is primary reflection, the relevant noise that produces between multiple reflection, and IV part is reasons for its use noise.
10. one kind is improved the device of pre-stack depth migration imaging precision, it is characterized in that, this device comprises data read module, associating pre-stack depth migration processing module, Free Surface multiple reflection prediction module, interference noise generation module, interference noise cancellation module, image-forming module, wherein:
Described data read module, for reading source data and prestack shot gather data, described source data comprises source wavelet, and described prestack shot gather data comprises primary reflection and multiple reflection;
Described associating pre-stack depth migration processing module, for carrying out pre-stack depth migration process to source data and prestack shot gather data, obtaining primary reflection and combining pre-stack depth migration result with multiple reflection;
Described Free Surface multiple reflection prediction module, for adopting Free Surface related multiple Forecasting Methodology to the multiple reflection in prestack shot gather data, obtains the predicted data of surface-related multiple;
Described interference noise generation module, for carrying out pre-stack depth migration process to the predicted data of source data and surface-related multiple, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces;
Described interference noise cancellation module, for primary reflection being combined pre-stack depth migration result with multiple reflection and source wavelet subtracts each other by mating with the interference noise that the surface-related multiple of prediction produces, the primary reflection after the interference noise that obtains decaying combines pre-stack depth migration result with multiple reflection;
Described image-forming module, is shown as seismic section image for the primary reflection after decay interference noise is combined pre-stack depth migration result with multiple reflection.
11. a kind of devices improving pre-stack depth migration imaging precision as claimed in claim 10, it is characterized in that, described associating pre-stack depth migration processing module specifically comprises: down-going wave fields processing module, upstream wave field processing module, pre-stack depth migration operator module, wherein:
Described down-going wave fields processing module, for being set to down-going wave fields by source wavelet and prestack shot gather data simultaneously;
Described upstream wave field processing module, for being set to upstream wave field by prestack shot gather data;
Described pre-stack depth migration operator module, for carrying out pre-stack depth migration process to down-going wave fields and upstream wave field based on the pre-stack depth migration operator of wave equation, obtaining primary reflection and combining pre-stack depth migration result with multiple reflection.
12. a kind of devices improving pre-stack depth migration imaging precision as claimed in claim 10, it is characterized in that, described interference noise generation module specifically comprises: down-going wave fields processing module, upstream wave field processing module, pre-stack depth migration operator module, wherein:
Described down-going wave fields processing module, for being set to down-going wave fields by source wavelet;
Described upstream wave field processing module, for being set to upstream wave field by the predicted data of surface-related multiple;
Described pre-stack depth migration operator module, for carrying out pre-stack depth migration process, the interference noise that the surface-related multiple obtaining source wavelet and prediction produces to down-going wave fields and upstream wave field based on the pre-stack depth migration operator of wave equation.
13. a kind of devices improving pre-stack depth migration imaging precision as claimed in claim 10, it is characterized in that, described interference noise cancellation module specifically comprises matching module and subtraction module, wherein:
The interference noise that described matching module is used for the surface-related multiple that primary reflection combines pre-stack depth migration result and source wavelet and prediction with multiple reflection to produce carries out Least squares matching;
Described subtraction module is used for the result after by coupling and carries out subtracting each other process.
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