CN105301639A - Speed field inversion method and device based on VSP double-weight travel time tomography - Google Patents

Abstract

The invention discloses a speed field inversion method and device based on VSP double-weight travel time tomography, and relates to the technical field of geophysical exploration, and the method and device can improve the accuracy and reliability of the tomography inversion results. The method comprises that VSP earthquake data is collected within an area to obtain an initial speed model of the area; a credibility model of the area is established according to the distances to a well and depths to the earth surface of different positions in the area; a grid slowness disturbance value in the area is obtained based on the observation parameters during VSP earthquake data collection, the initial speed model of the area and the credibility model; grid speed in the initial speed model of the area is corrected according to the grid slowness disturbance value to obtain a new speed model of the area; and first-arrival theoretical travel time is obtained based on the new speed module, whether the difference between the first-arrival theoretical travel time and practical travel time satisfies a preset threshold is determined, and if yes, a tomography inversion speed field is output. The method can be used to effectively improve the accuracy and reliability of the tomography inversion results.

Description

Based on method and the device thereof of the two weighting chromatography inversion speed field of VSP whilst on tour

Technical field

The present invention relates to technical field of geophysical exploration, particularly a kind of method based on the two weighting chromatography inversion speed field of VSP whilst on tour and device thereof.

Background technology

So far, China's western region pre-stack depth migration still not yet obtains remarkable effect, and its essential reason is the velocity field owing to being difficult to determine underground medium.Under this kind of area, velocity field is difficult to determine to there is factors, comprising: in China's western region, the massif low velocity layer thickness of arid is large, reaches 500-1200 rice; The methods such as common little refraction and micro logging can only inverting area compared with the velocity field of shallow portion, completely can not the velocity field in deep, inverting area; Employing is beaten deep-well and is asked the method cost of top layer velocity field excessive, and the velocity field obtained after operation like this is enough inaccurate; Can run into after ray goes down in common chromatography method, return less than ground, can not form the situation of diving Wave.Factor many above finally all causes obtaining the velocity field met the demands.

Owing to there is all unfavorable factors, conventional method all cannot be proved effective, this area researchist starts to attempt new method and carrys out the velocity field that inverting obtains underground medium, carrys out the velocity field of inverting underground medium comprising the method based on vertical seismic profiling (VSP) VSP (VerticalSeismicProfiling) first break time chromatography.The tomography signal that to be a kind of utilization observe at detection target surface, to ask for the inversion method of target internal information, is applied to medical domain the earliest, expands to other neck subsequently.In seismic exploration problem, tomography is exactly utilize the information such as the whilst on tour of seismic event, amplitude and the waveform that are recorded on earth's surface or downhole receiving, rebuilds the isoparametric distribution of speed of underground medium.At present, be ray travel time tomography at the most widely used chromatography imaging method of field of seismic exploration, namely utilize seimic travel time and its raypath propagated to carry out inverting underground medium speed.Conventional travel time tomography method has Inverse Projection, algebraic reconstruction technique, simultaneous iterative reconstruc tion technique, singular value decomposition method, least square QR decomposition method and least-squared conjugate gradient method etc.Present inventor finds that these algorithms above-mentioned all distribute to walk time error according to the ray length through unit grid, walking time error is that point of firing from ground looks for ray to arrive VSP down-hole point, according to the speed iterating velocity field, calculate its travelling walk time, the error time of to try to achieve time of arrival with real VSP direct wave again, although distribute to walk time error according to ray length finally can obtain down-hole underground medium speed at a distance comparatively accurately, but the underground medium speed goes distributing to walk the well side, down-hole that time error can make to obtain on the contrary according to ray length is inaccurate, so, the inaccuracy of the underground medium speed that down-hole well is other cannot satisfy the demands, and then cause medium velocity under base area to carry out the precision of the result of tomographic inversion and reliability not enough.

Summary of the invention

In order to overcome the above-mentioned defect of prior art, provide a kind of method based on the two weighting chromatography inversion speed field of VSP whilst on tour and device in the embodiment of the present invention, it can improve precision and the reliability of tomographic inversion result.

The concrete technical scheme of the embodiment of the present invention is:

Based on a method for the two weighting chromatography inversion speed field of VSP whilst on tour, it comprises:

In region, gather vertical seismic profiling (VSP) VSP geological data thus obtain the first break time of VSP seismologic record, obtaining the initial velocity model in described region according to the first break time of described VSP seismologic record;

The credibility model in described region is set up in each position in described region apart from the distance of well and its degree of depth apart from earth's surface according to it;

Grid slowness disturbed value in described region is obtained based on observed parameter, the initial velocity model in described region and described credibility model when gathering VSP geological data;

By grid slowness disturbed value in described region, the new rate pattern in described region is obtained to the speed correction of grid in the initial velocity model in described region;

Based on described new rate pattern obtain first arrival theory walk time, judge described first arrival theoretical walk time with actual walk time difference whether meet predetermined threshold values, if meet, then output chromatography inversion speed field.

Based on the two weighting chromatography inversion speed field of VSP whilst on tour a device, it comprises:

Initial velocity model sets up module, and it sets up the initial velocity model in described region according to the vertical seismic profiling (VSP) VSP geological data gathered in region;

Credibility model sets up module, and it sets up the credibility model in described region apart from the distance of well and its degree of depth apart from earth's surface according to each position in described region;

Grid slowness disturbed value computing module, observed parameter when its initial velocity model according to described region, credibility model and collection VSP geological data obtains grid slowness disturbed value in described region;

Tomographic inversion velocity field module, it obtains the new rate pattern in described region by grid slowness disturbed value in described region to the speed correction of grid in the initial velocity model in described region, and then calculate first arrival theory when walking, when described first arrival is theoretical walk time and actual walk time difference meet the threshold values of regulation time, export chromatography inversion speed field, when described first arrival is theoretical walk time with actual walk time difference satisfied specify threshold values time, then based on observed parameter, the new rate pattern in described region and described credibility model obtain grid slowness disturbed value in described region again, and then carry out iteration, until described first arrival theoretical walk time and actual walk time difference meet the threshold values of regulation.

The method based on the two weighting chromatography inversion speed field of VSP whilst on tour in the embodiment of the present invention and device, it is when walking time error Distribution Calculation, except the ray length of unit grid, also introduce credibility model, the ray length of range site grid and confidence level revise grid slowness disturbed value, control the distribution of time error, thus improve reliability and the precision of tomographic inversion result, improve topographic imaging by velocity result.

Accompanying drawing explanation

Accompanying drawing described here only for task of explanation, and is not intended to limit scope disclosed by the invention by any way.In addition, the shape of each parts in figure and proportional sizes etc. are only schematic, for helping the understanding of the present invention, are not the shape and the proportional sizes that specifically limit each parts of the present invention.Those skilled in the art under the teachings of the present invention, can select various possible shape and proportional sizes to implement the present invention as the case may be.

Fig. 1 is the present invention's process flow diagram in an embodiment.

Fig. 2 is the geologic model and VSP inspection well that in the embodiment of the present invention, forward simulation adopts.

Fig. 3 is forward simulation recording geometry schematic diagram in the embodiment of the present invention.

Fig. 4 is the initial velocity model set up in the embodiment of the present invention.

Fig. 5 is the credibility model set up in the embodiment of the present invention.

Fig. 6 is the velocity field that in the embodiment of the present invention, tomographic inversion obtains.

Fig. 7 is the structural representation of device in the embodiment of the present invention.

Embodiment

By reference to the accompanying drawings with the description of the specific embodiment of the invention, can clearly understand details of the present invention.But the specific embodiment of the present invention described here, only for explaining object of the present invention, and can not to be understood as by any way be limitation of the present invention.Under the teachings of the present invention, technician can conceive based on distortion possible arbitrarily of the present invention, and these all should be regarded as belonging to scope of the present invention.

Fig. 1 is the present invention's process flow diagram in an embodiment, as shown in Figure 1, a kind of method based on the two weighting chromatography inversion speed field of VSP whilst on tour, it comprises the following steps:

S101: gather vertical seismic profiling (VSP) VSP geological data thus obtain the first break time of VSP seismologic record in region, obtain the initial velocity model in region according to the first break time of VSP seismologic record, it comprises the following steps:

S201: gather deep-well vertical seismic profiling (VSP) VSP geological data by the method for ray-tracing forward modeling in region, utilizes first break time to pick up the first break time of software pickup VSP seismologic record.Fig. 2 is the geologic model and VSP inspection well that in the embodiment of the present invention, forward simulation adopts, and as shown in Figure 2, Fig. 2 middle and upper part is derrick, and black line vertical in Fig. 2 is inspection well.In region, look for 3 to 5 mouthfuls of wells, arrive different depth by under multi-level downhole wave detector, near the borehole wall, and settle GPS time service seismograph at well head; Then adopt the method for putting little big gun, the dose of 0.5kg to 1kg can be adopted, according to the complexity of regional tectonics, can blow out with GPS time service blaster on mountain; Fig. 3 is forward simulation recording geometry schematic diagram in the embodiment of the present invention, and as shown in Figure 3, big gun is apart from being 100 meters, and fall apart from 25 meters, the scale of blowing out is 101 big gun * 215 roads.Utilize GPS time service seismograph round-the-clock reception VSP seismologic record.According to the first break time of the VSP seismologic record pickup zero-offset VSP that GPS time service seismograph receives, detailed process is as follows, first break time is utilized to pick up software, the every first break time TR (I) together of pickup zero-offset VSP, I=1 ... N, wherein, I is Seismic Traces sequence number, and N is the total number of channels of VSP seismologic record.

S202: the geological structure information utilizing region known sets up initial construction model.

Set up initial construction model according to the geological structure information that region is known, known geological structure information at least comprises the degree of depth of subsurface reflective boundary, the form of reflecting interface, one of position of fault and fault strike.

S203: the first break time inverting based on VSP seismologic record obtains the interval velocity in well week, processes the initial model speed obtaining grid to initial construction model by interval velocity.

First break time based on pickup zero-offset VSP carries out the interval velocity that inverting obtains well week, specifically under zero well constraint inversion condition, the time difference of the first arrival arrival of different depth is obtained according to the first break time of zero-offset VSP, calculate the interval velocity in each degree of depth again, also just obtain the interval velocity in well week.Then by interval velocity, initial construction model is processed to the initial model speed obtaining grid, Fig. 4 is the initial velocity model set up in the embodiment of the present invention.For the model meshes near hole diameter in initial construction model, the interval velocity of zero well constraint inversion of this well is utilized to fill, for the model meshes away from this well in initial construction model, according to the distance of this grid to neighbouring two mouthfuls of wells, distance weighted calculating is carried out to the interval velocity of zero well constraint inversion of two mouthfuls of wells near this grid, obtains the initial model speed of this grid.In the process of the above-mentioned initial model speed obtaining grid, the data of the main VSP of dependence well are carried out filling process with the initial model speed obtaining grid to both sides by the centre of initial construction model.

S204: the initial model speed based on grid carries out the initial mesh rate pattern that layered encryption and Mesh Smoothing process obtain region.Layered encryption is carried out to the initial model speed of grid and Mesh Smoothing process obtains initial mesh rate pattern V (ix, jz), wherein ix represents the grid sequence number of rate pattern X-direction, ix=1 ... NX, NX represents model grid number in the X direction, jz represents the grid sequence number of rate pattern Z-direction, jz=1 ... NZ, NZ represent model grid number in z-direction.

S102: the credibility model in region is set up in each position in region apart from the distance of well and its degree of depth apart from earth's surface according to it.

Fig. 5 is the credibility model set up in the embodiment of the present invention, as shown in Figure 5, the a top layer speed clearly given confidence value in position in the other and earth's surface of well in region, in region, other position is along with the increasing progressively of the degree of depth on the Distance geometry distance earth's surface apart from well, confidence value reduces gradually, thus the credibility model N (x of forming region, z), wherein x is the grid sequence number of rate pattern X-direction, x=1 ... NX, NX are model grid number in the X direction, and z is the grid sequence number of rate pattern Z-direction, z=1 ... NZ, NZ are model grid number in z-direction.

S103: obtain grid slowness disturbed value in region based on observed parameter, the initial velocity model in region and credibility model when gathering VSP geological data, it specifically comprises the following steps:

S301: the theoretical first break time of VSP theogram, the travel path of every ray together and the length of ray in the unit grid passed together with obtaining often according to observed parameter and the initial velocity model in region.

Initial velocity model according to region obtains following parameter with observed parameter by the method for ray tracing: the theoretical first break time Ts (i) of VSP theogram together with every, wherein i=1 ... N, i is Seismic Traces sequence number, and N is the total number of channels of VSP seismologic record; Every ray travel path (Rx (j) together, Ry (j)), wherein, j=1 ... M, M is the grid sum that current ray passes, and Rx (j) and Ry (j) are respectively the X-direction of a jth grid and the grid sequence number of Z-direction that ray passes; The length Lij of ray in the unit grid passed, wherein, i is the sequence number of ray, and j is the sequence number of model unit grid.Observed parameter is specially involved by step S201 Fig. 3: big gun is apart from being 100 meters, and fall apart from 25 meters, the scale of blowing out is 101 big gun * 215 roads.

S302: obtain grid slowness disturbed value in region based on length in the unit grid passed of the travel path of the theoretical first break time of every one VSP theogram, every one ray, ray and credibility model.

To obtain in region in grid slowness disturbed value based on length in the unit grid passed of the travel path of the theoretical first break time of every one VSP theogram, every one ray, ray and credibility model, be specially the region for there being J grid, during the situation of I bar ray information, in its region, the computing formula of grid slowness disturbed value is as follows:

${\mathrm{\ΔS}}_j=\frac{\mathrm{\η}}{{\mathrm{\λ}}_j}\underset{i=1}{\overset{I}{\Σ}}\frac{{\mathrm{dT}}_i\·\left(\frac{L_{ij}}{{\mathrm{SL}}_i}\right)\·\left(\frac{1}{N_{ij}\·{\mathrm{SN}}_i}\right)}{{\mathrm{SLN}}_i}$

${\mathrm{\λ}}_j=\underset{i=1}{\overset{I}{\Σ}}{L}_{ij}^{\mathrm{\α}},(j=1,2...J)$

${\mathrm{\ρ}}_i=\underset{j=1}{\overset{J}{\Σ}}{L}_{ij}^{2-\mathrm{\α}},(i=1,2...I)$

${\mathrm{SL}}_i=\underset{j=1}{\overset{J}{\Σ}}{L}_{ij},(i=1,2...I)$

${\mathrm{SN}}_i=\underset{j=1}{\overset{J}{\Σ}}{N}_{ij},(i=1,2...I)$

${\mathrm{SLN}}_i=\underset{j=1}{\overset{j}{\Σ}}\left(\frac{L_{ij}}{{\mathrm{SL}}_i}\right)\·\left(\frac{1}{N_{ij}\·{\mathrm{SN}}_i}\right),(i=1,2...I)$

Wherein, L _ijrepresent the ray length of i-th ray on a jth grid, N _ijrepresent the confidence level of i-th ray on a jth grid, SL _irepresent the total length of i-th ray, SN _irepresent total confidence level of i-th ray, η and α represents the relaxation factor of control convergence speed and stability, and I represents total number of rays, and J represents total grid number.

Distribute not only relevant with ray length owing to walking time error, also relevant with the azimuthal distribution of the ray in unit grid, simple ray length is lost control of away time error and is distributed, so distribute to carry out walking time error more accurately, when grid slowness disturbed value calculates in region, introduce the confidence level of unit grid in credibility model.

In above-mentioned zone grid slowness disturbed value computing formula in ray order be ascending according to well constraint inversion, acceptance point degree of depth order from shallow to deep sorts.The span of the η in the computing formula of the grid slowness disturbed value of above-mentioned model can be (0,2), and the span of α can be (0,2).

S104: the new rate pattern in region is obtained to the speed correction of grid in the initial velocity model in region by the grid slowness disturbed value of model.

Utilize speed revise of grid slowness disturbed value to grid corresponding in the initial velocity model in region in region to obtain the new rate pattern in region, speed correction formula is specially:

$V(ix,jz)=V(ix,jz)+\frac{1}{{\mathrm{\ΔS}}_j}$

Wherein, ix represents the grid sequence number of the initial velocity model X-direction in region, ix=1 ..., NX, NX represents the grid number in the initial velocity model X-direction in region, jz represents the grid sequence number of the initial velocity model Z-direction in region, jz=1 ..., NZ, NZ represent grid number in the initial velocity model Z-direction in region, Δ S _jrepresent grid slowness disturbed value in region.

In to initial model during the speed amendment of grid, can judge the rationality of amended speed, the speed correction exceeding given speed scope is limited.Meanwhile, can also confidence level revised to the speed of grid time row judge, if amended confidence level is too low, such as through current grid ray very little, generally can think when being less than 5, then not revise the speed of current grid.

S105: by linear filtering method to the smoothing process of velocity field in the new rate pattern in region.

When new rate pattern adopts the level and smooth grid of Kp × Lp, then the formula in linear filtering method is specially:

$V(m,n)=\frac{1}{KP\×LP}\underset{k=-1}{\overset{Kp}{\Σ}}\underset{l=-1}{\overset{Lp}{\Σ}}V(m+i,n+j)$

Wherein, m, n represent horizontal ordinate and the ordinate of grid mid point respectively, and V (m, n) represents that grid mid point is the Grid Velocity of (m, n).This step can exceptional value in release rate field, to ensure the reliability of ray tracing result.

S106: based on new rate pattern obtain first arrival theory walk time, judge first arrival theoretical walk time with actual walk time difference whether meet threshold values specify, if satisfied, then output chromatography inversion speed field.If do not meet, again obtain the grid slowness disturbed value of model based on the new rate pattern in observed parameter, region and credibility model, carry out iteration thus, until first arrival theoretical walk time and actual walk time difference meet the threshold values of regulation.

Fig. 6 is the velocity field that in the embodiment of the present invention, tomographic inversion obtains, as shown in Figure 6, when the theory utilizing new rate pattern forward modelling to obtain VSP first arrival is walked, judge first arrival theoretical walk time and collection VSP geological data in actual walk time the difference of mean value whether meet predetermined threshold values, if meet predetermined threshold values, then export chromatography inversion speed field; If do not meet predetermined threshold values, then repeat step S103 to S105 to carry out iteration, until first arrival theoretical walk time and collection VSP geological data in actual walk time the difference of mean value meet predetermined threshold values, then export chromatography inversion speed field.

Feature extremely uneven according to VSP primary wave radiation profile in the embodiment of the present invention, in tomographic inversion computation process, except revising grid slowness according to the ray length in unit grid, also introduce credibility model and different confidence levels is arranged to grid matrix, and adopt two weighted formula of the confidence level of the ray length in grid and grid to revise grid slowness disturbed value.When the correction of grid slowness, ascending according to well constraint inversion, degree of depth order from shallow to deep one by one ray carries out, and so can improve reliability and the precision of tomographic inversion result.Utilize ray length and confidence level two parameters to control away the distribution of time error by this method, effectively can improve reliability and the precision of tomographic inversion result, and then improve topographic imaging by velocity result.

Fig. 7 is the structural representation of device in the embodiment of the present invention, as shown in Figure 7, a kind of based on the two weighting chromatography inversion speed field of VSP whilst on tour device, it comprises:

Initial velocity model sets up module, and it sets up the initial velocity model in region according to the vertical seismic profiling (VSP) VSP geological data gathered in region;

Credibility model sets up module, and it sets up the credibility model in region apart from the distance of well and its degree of depth apart from earth's surface according to each position in region;

The grid slowness disturbed value computing module of model, observed parameter when its initial velocity model according to region, credibility model and collection VSP geological data obtains grid slowness disturbed value in region;

Tomographic inversion velocity field module, it obtains the new rate pattern in region by grid slowness disturbed value in region to the speed correction of grid in the initial velocity model in region, and then calculate first arrival theory when walking, originally to theoretical walk time and actual walk time difference meet the threshold values of regulation time, export chromatography inversion speed field, originally to theoretical walk time with actual walk time difference satisfied specify threshold values time, then based on observed parameter, the new rate pattern in region and credibility model obtain grid slowness disturbed value in region again, and then carry out iteration, until first arrival theoretical walk time and actual walk time difference meet the threshold values of regulation.

System, device, module or unit that above-described embodiment is illustrated, specifically can be realized by computer chip or entity, or be realized by the product with certain function.

For convenience of description, various unit is divided into describe respectively with function when describing above device.Certainly, the function of each unit can be realized in same or multiple software and/or hardware when implementing the application.

Each embodiment in this instructions all adopts the mode of going forward one by one to describe, between each embodiment identical similar part mutually see, what each embodiment stressed is the difference with other embodiments.Especially, for system embodiment, because it is substantially similar to embodiment of the method, so description is fairly simple, relevant part illustrates see the part of embodiment of the method.

The application can describe in the general context of computer executable instructions, such as program module.Usually, program module comprises the routine, program, object, assembly, data structure etc. that perform particular task or realize particular abstract data type.Also can put into practice the application in a distributed computing environment, in these distributed computing environment, be executed the task by the remote processing devices be connected by communication network.In a distributed computing environment, program module can be arranged in the local and remote computer-readable storage medium comprising memory device.

Although depict the application by embodiment, those of ordinary skill in the art know, the application has many distortion and change and do not depart from the spirit of the application, and the claim appended by wishing comprises these distortion and change and do not depart from the spirit of the application.

Claims (12)

1., based on a method for the two weighting chromatography inversion speed field of VSP whilst on tour, it is characterized in that, it comprises:

In region, gather vertical seismic profiling (VSP) VSP geological data thus obtain the first break time of VSP seismologic record, obtaining the initial velocity model in described region according to the first break time of described VSP seismologic record;

The credibility model in described region is set up in each position in described region apart from the distance of well and its degree of depth apart from earth's surface according to it;

Grid slowness disturbed value in described region is obtained based on observed parameter, the initial velocity model in described region and described credibility model when gathering VSP geological data;

By grid slowness disturbed value in described region, the new rate pattern in described region is obtained to the speed correction of grid in the initial velocity model in described region;

Based on described new rate pattern obtain first arrival theory walk time, judge described first arrival theoretical walk time with actual walk time difference whether meet predetermined threshold values, if meet, then output chromatography inversion speed field.

2. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 1, it is characterized in that, based on described new rate pattern obtain first arrival theory walk time, judge described first arrival theoretical walk time and actual walk time difference whether meet predetermined threshold values, if do not meet, the grid slowness disturbed value in region is then again obtained based on the new rate pattern in observed parameter, described region and described credibility model, and then carry out loop iteration, until described first arrival theoretical walk time and actual walk time difference meet the threshold values of regulation.

3. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 1, it is characterized in that, to obtain in described region, in grid slowness disturbed value, specifically comprising the following steps based on observed parameter, the initial velocity model in described region and described credibility model when gathering VSP geological data in step:

The theoretical first break time of VSP theogram, the travel path of every ray together and the length of ray in the unit grid passed together with obtaining often according to observed parameter and the initial velocity model in described region;

Grid slowness disturbed value in described region is obtained based on length in the unit grid passed of the travel path of the theoretical first break time of every one VSP theogram, every one ray, ray and described credibility model.

4. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 2, it is characterized in that, obtain in the grid slowness disturbed value of model in step based on length in the unit grid passed of the travel path of the theoretical first break time of every one VSP theogram, every one ray, ray and described credibility model, be specially the described region for there being J grid, during the situation of I bar ray information, in region described in it, the computing formula of grid slowness disturbed value is as follows:

${\mathrm{\ΔS}}_j=\frac{\mathrm{\η}}{{\mathrm{\λ}}_j}\underset{i=1}{\overset{I}{\Σ}}\frac{{\mathrm{dT}}_i\·\left(\frac{L_{ij}}{{\mathrm{SL}}_i}\right)\·\left(\frac{1}{N_{ij}\·{\mathrm{SN}}_i}\right)}{{\mathrm{SLN}}_i}$

${\mathrm{\λ}}_j=\underset{i=1}{\overset{I}{\Σ}}{L}_{ij}^{\mathrm{\α}},(j=1,2...J)$

${\mathrm{\ρ}}_i=\underset{j=1}{\overset{J}{\Σ}}{L}_{ij}^{2-\mathrm{\α}},(i=1,2...I)$

${\mathrm{SL}}_i=\underset{j=1}{\overset{J}{\Σ}}{L}_{ij},(i=1,2...I)$

${\mathrm{SN}}_i=\underset{j=1}{\overset{J}{\Σ}}{N}_{ij},(i=1,2...I)$

$SLN=\underset{j=1}{\overset{j}{\Σ}}\left(\frac{L_{ij}}{{\mathrm{SL}}_i}\right)\·\left(\frac{1}{N_{ij}\·{\mathrm{SN}}_i}\right),(i=1,2...I)$

Wherein, L _ijrepresent the ray length of i-th ray on a jth grid, N _ijrepresent the confidence level of i-th ray on a jth grid, SL _irepresent the total length of i-th ray, SN _irepresent total confidence level of i-th ray, η and α represents the relaxation factor of control convergence speed and stability, and I represents total number of rays, and J represents total grid number.

5. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 3, it is characterized in that, in described region grid slowness disturbed value computing formula in ray order be ascending according to its well constraint inversion, acceptance point degree of depth order from shallow to deep sorts.

6. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 3, it is characterized in that, the span of the η in the computing formula of the grid slowness disturbed value of described model is (0,2), the span of α is (0,2).

7. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 1, it is characterized in that: step by grid slowness disturbed value in described region to the initial velocity model in described region in the speed correction of grid obtain in the new rate pattern in described region, be specially and utilize speed revise of grid slowness disturbed value to grid corresponding in the initial velocity model in described region in described region to obtain the new rate pattern in described region, speed correction formula is specially:

$V(ix,jz)=V(ix,jz)+\frac{1}{{\mathrm{\ΔS}}_j}$

Wherein, ix represents the grid sequence number of the initial velocity model X-direction in described region, ix=1 ..., NX, NX represents the grid number in the initial velocity model X-direction in described region, jz represents the grid sequence number of the initial velocity model Z-direction in described region, jz=1 ..., NZ, NZ represent grid number in the initial velocity model Z-direction in described region, Δ S _jrepresent grid slowness disturbed value in described region.

8. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 1, it is characterized in that, in region, gather vertical seismic profiling (VSP) VSP geological data in step thus obtain the first break time of VSP seismologic record, obtain according to the first break time of VSP seismologic record, in the initial velocity model in described region, specifically comprising:

In region, gather deep-well vertical seismic profiling (VSP) VSP geological data by the method for ray-tracing forward modeling, utilize first break time to pick up the first break time of software pickup VSP seismologic record;

The known geological structure information in described region is utilized to set up initial construction model;

First break time inverting based on VSP seismologic record obtains the interval velocity in well week, by interval velocity, initial construction model is processed to the initial model speed obtaining grid;

Initial model speed based on grid carries out the initial mesh rate pattern that layered encryption and Mesh Smoothing process obtain described region.

9. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 1, it is characterized in that, before step obtains when first arrival theory is walked based on new rate pattern, described method also comprises: by linear filtering method to the smoothing process of velocity field in the new rate pattern in described region.

10. the method based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 8, is characterized in that, when described new rate pattern adopts the level and smooth grid of Kp × Lp, then the formula in linear filtering method is specially:

$V(m,n)=\frac{1}{Kp\×Lp}\underset{k=-1}{\overset{Kp}{\Σ}}\underset{l=-1}{\overset{Lp}{\Σ}}V(m+i,n+j)$

Wherein, m, n represent horizontal ordinate and the ordinate of grid mid point respectively, and V (m, n) represents that grid mid point is the Grid Velocity of (m, n).

11. methods based on the two weighting chromatography inversion speed field of VSP whilst on tour according to claim 1, it is characterized in that: set up in the credibility model in described region according to it apart from the distance of well and its degree of depth apart from earth's surface in step each position in described region, be specially: a top layer speed clearly given confidence value in position in the other and earth's surface of well in described region, in described region, other position is along with the increasing progressively of the degree of depth on the Distance geometry distance earth's surface apart from well, confidence value reduces gradually, thus form the credibility model N (x in described region, z), wherein x represents the grid sequence number of credibility model X-direction, z represents the grid sequence number of credibility model Z-direction.

12. 1 kinds based on the two weighting chromatography inversion speed field of VSP whilst on tour device, it is characterized in that, it comprises:

Initial velocity model sets up module, and it sets up the initial velocity model in described region according to the vertical seismic profiling (VSP) VSP geological data gathered in region;

Credibility model sets up module, and it sets up the credibility model in described region apart from the distance of well and its degree of depth apart from earth's surface according to each position in described region;

Grid slowness disturbed value computing module, observed parameter when its initial velocity model according to described region, credibility model and collection VSP geological data obtains grid slowness disturbed value in described region;

Tomographic inversion velocity field module, it obtains the new rate pattern in described region by grid slowness disturbed value in described region to the speed correction of grid in the initial velocity model in described region, and then calculate first arrival theory when walking, when described first arrival is theoretical walk time and actual walk time difference meet the threshold values of regulation time, export chromatography inversion speed field, when described first arrival is theoretical walk time with actual walk time difference satisfied specify threshold values time, then based on observed parameter, the new rate pattern in described region and described credibility model obtain grid slowness disturbed value in described region again, and then carry out iteration, until described first arrival theoretical walk time and actual walk time difference meet the threshold values of regulation.