CN103576188A - Seismic source location method eliminating influences of velocity errors - Google Patents

Abstract

The invention provides a seismic source location method eliminating influences of velocity errors, and belongs to the field of seismic exploration. According to the method, a velocity error model related to velocity is obtained through a given seismic source position, the velocity error model is applied to an objective function, all the possible seismic source positions are scanned, and the coordinate of the point which enables the value of the objective function to be minimum is the coordinate of the seismic source to be located. The method eliminates the strong dependence of seismic locating accuracy on the velocity model, can achieve accurate location on the seismic source, changes of subsurface structures and fluid can be detected through the accurate location on the seismic source, and therefore the exploitation and the extraction of petroleum, natural gas and the like can be further guided.

Description

A kind of focus localization method of release rate error effect

Technical field

The invention belongs to field of seismic exploration, be specifically related to a kind of focus localization method of release rate error effect, be mainly used in resources-type exploitation field, comprise the field of seismic exploration such as coal, oil and natural gas, also can be used for the monitoring of engineering geophysics and conventional earthquake location.

Background technology

Earthquake location is one of problem the most basic in seismology, significant such as the basic problem in these type of seismology such as geometrical construction of seismic activity structure, earth ' s internal structure, focus for research.Earthquake orientation problem simplified summary is: according to the station, to earthquake observational data then, determine volume coordinate and the origin time of earthquake of focus, sometimes give the evaluation to separating.Intelligent numerical value automatic positioning method based on science calculating and computer technology becomes the main stream approach of current earthquake location, now widely used method for computer positioning is the classical way of Geiger and the various linear methods set up on this basis: co-located method, Relative localization method, and dual residual error method etc.

Earthquake location technology is not only applied to earthquake field, at the end of the nineties, be introduced in the resource exploitation industries such as oil and coal, in exploitation, the event such as rock burst is compared with earthquake, because of its energy less, be referred to as microearthquake, the monitoring technology of microearthquake can be good at understanding underground variation, be widely used at present the aspects such as hydrocarbon-bearing pool dynamic monitoring, geothermal activities monitoring, coalfield dynamic monitoring, engineering dynamic monitoring, dynamically significant to oil-field development by microearthquake method Real-Time Monitoring field produces.

The location technology to focus such as the microearthquake monitoring in earthquake location, oil-gas exploration and engineering dynamic monitoring, its ultimate principle is identical, according to time of arrival and the geologic model being finally inversed by, by least square method, make source location hourage of calculating of location and quadratic sum minimum hourage of actual observation.Determined source location precision is by two aspect factor controllings, (1) rate pattern, and rate pattern is more accurate, and focus positioning precision is higher, and vice versa, (2) actual whilst on tour error of observing.First factor mainly determines by the completeness of observation data, limitation due to recording geometry, rate pattern inverting is very difficult often, main manifestations is that multi-solution and error ratio are larger, second factor is main is correlated with instrument and relevant operating personnel, is objective unmodifiable factor.

Summary of the invention

The object of the invention is to solve the difficult problem existing in above-mentioned prior art, a kind of focus localization method of release rate error effect is provided, it is a kind of method of earthquake locating to rate pattern error relative insensitivity, eliminate the strong dependence of earthquake location accuracy to rate pattern, by thereby focus is accurately located to the variation that detects underground structure and fluid, instruct exploitation and the exploitation of oil, rock gas etc.

The present invention is achieved by the following technical solutions:

A kind of focus localization method of release rate error effect, described method is by the position of known focus, ask for a velocity error model with velocity correlation, velocity error model is applied in objective function, then scan all possible source location, the coordinate that finds the point of the value minimum that makes objective function is exactly the coordinate of focus to be positioned.

Describedly ask for one and be achieved in that with the velocity error model of velocity correlation

Be provided with n geophone station, get known focus A (x _a, y _a, z _a), by formula (3), calculating focus A is T to the calculating whilst on tour of each geophone station _i ^a,

${T_i}^A=\frac{{l_i}^A}{v}---\left(3\right)$

Wherein, T _i ^afor the calculating whilst on tour of focus A to i geophone station,

for the distance of focus A to i geophone station, v is velocity of propagation, and the velocity error model at i geophone station place is so:

${\mathrm{\ϵ}}_i=\frac{{T_i}^A}{{t_i}^A}---\left(6\right)$

Wherein

for focus A propagates into the observation whilst on tour of each geophone station, ε _ivelocity error ratio for i geophone station place.

Described velocity error model is applied in objective function, then scans all possible source location, the coordinate that finds the point of the value minimum that makes objective function is exactly that the coordinate of focus to be positioned is achieved in that

For any one focus to be positioned, be handled as follows:

(1) the observation whilst on tour from this focus to each geophone station, find minimum observation whilst on tour, the corresponding geophone station of this minimum observation whilst on tour is made as geophone station K, then calculate this focus to the observation whilst on tour of each geophone station with this focus to the mistiming between the observation whilst on tour of geophone station K, this mistiming is to observe travel-time difference;

(2) in given scope, according to described velocity error model and formula (5), calculate each focus to the calculating hourage of each geophone station, and ask for each focus to the calculating whilst on tour of each geophone station with each focus to the mistiming between the calculating whilst on tour of geophone station K, this mistiming is calculating travel-time difference;

$T_i=\frac{l_i}{{\mathrm{v\ϵ}}_i}---\left(5\right)$

(3) take the quadratic sum of the difference between the calculating travel-time difference that observation travel-time difference that step (1) obtains and step (2) obtain is objective function, the institute of traversal in given range a little, makes the coordinate of point of the value minimum of described objective function be the coordinate of focus to be positioned.

Compared with prior art, the invention has the beneficial effects as follows: the inventive method has been eliminated the strong dependence of earthquake location accuracy to rate pattern, can realize the accurate location of focus, by thereby focus is accurately located to the variation that detects underground structure and fluid, instruct exploitation and the exploitation of oil, rock gas etc.

Accompanying drawing explanation

Fig. 1 is the model in the embodiment of the present invention 2.

Fig. 2 is the hourage observing in the embodiment of the present invention 2.

Fig. 3 is the section of the focus A that in the embodiment of the present invention 2, certain real data observes.

Fig. 4 is the section of the focus B that in the embodiment of the present invention 2, certain real data observes.

Fig. 5-1st, carries out the hourage of picking up after residual correction to Fig. 3 in the embodiment of the present invention 2.

Fig. 5-2nd, carries out the hourage of picking up after residual correction to Fig. 4 in the embodiment of the present invention 2.

Fig. 6 is the step block diagram of the inventive method.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail:

The first step: focus localization method (prior art)

If the observation of n geophone station is t while arriving ₁, t ₂..., t _n, ask focus (x ₀, y ₀, z ₀) and origin time of earthquake t ₀, make objective function

$\mathrm{\&phi;}({\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HDA00001934365000012.png"\; state="\{\{state\}\}">t</figure-callout>}}_0,x_0,{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="HDA00001934365000012.png"\; state="\{\{state\}\}">y</figure-callout>}}_0,z_0)=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{r}_i^2---\left(1\right)$

Minimum, wherein r _ifor residual error then;

r _i＝t _i-t ₀-T _i(x ₀，y ₀，z ₀) (2)

T _ifor the calculating whilst on tour of focus to i geophone station.

$T_i=\frac{l_i}{v}---\left(3\right)$

L wherein _ifor the distance of focus to i geophone station, v is velocity of propagation, makes objective function minimalization be also

${\&dtri;}_{\mathrm{\&theta;}}\mathrm{\&phi;}\left(\mathrm{\&theta;}\right)=0---\left(4\right)$

(4) formula is to the variable θ differentiate in function phi, and making its derivative is zero.

Wherein

$\mathrm{\&theta;}={({\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HDA00001934365000012.png"\; state="\{\{state\}\}">t</figure-callout>}}_0,x_0,{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="HDA00001934365000012.png"\; state="\{\{state\}\}">y</figure-callout>}}_0,z_0)}^T,{\&dtri;}_{\mathrm{\&theta;}}={(\frac{\&PartialD;}{{\&PartialD;\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HDA00001934365000012.png"\; state="\{\{state\}\}">t</figure-callout>}}_0},\frac{\&PartialD;}{{\&PartialD;tx}_0},\frac{\&PartialD;}{{\&PartialD;\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="HDA00001934365000012.png"\; state="\{\{state\}\}">y</figure-callout>}}_0},\frac{\&PartialD;}{{\&PartialD;z}_0})}^T$

At given range Ω, (its scope is determined according to the actual conditions in location, for example, in seismic prospecting, in well, inject fracturing liquid, mode by pressure break makes stratum crushing, thereby produces small focus, and stratum crushing scope is conventionally in 300 meters, at most can be over 500 meters, therefore given scope is the scope with 300 meters, pressure break center) in, traveling through all θ values, φ minimum is asks for focal point (x ₀, y ₀, z ₀).

Second step: (innovation of the present invention) set up and proofreaied and correct to velocity error

In actual applications, it is accurate that the speed v in formula (3) is difficult to ask, thereby cause T _ierror, finally causes focus location inaccurate, in order to overcome the problems referred to above, introduces velocity error parameter, and formula (3) is rewritten as:

$T_i=\frac{l_i}{v{\mathrm{\&epsiv;}}_i}---\left(5\right)$

ε wherein _ifor the velocity error ratio at i geophone station place, { ε _i(i=1, n) } be the error set of all geophone stations, this error set is called as error model.Asking for of error model, gets oriented certain focal point A (x _a, y _a, z _a), by formula (3), calculating focus A is T to the calculating whilst on tour of each geophone station _i ^a, the velocity error function at i geophone station place is so:

${\mathrm{\&epsiv;}}_i=\frac{{T_i}^A}{{t_i}^A}---\left(6\right)$

Wherein

(t namely _i-t ₀) propagate into the observation whilst on tour of each geophone station for focus A.Error model has been set up in application of formula (5), (6), pass through error model, release rate model is forbidden the impact causing, greatly improve focus positioning precision, conventionally the selection principle of focus A is: best point (the artificial experience judgement of precision and reliability in all focus location, be generally amplitude strong, disturb less, identification degree is high), or obtain the position of focus A and the time of its observation by artificial excitation's mode.Calculating whilst on tour is to calculate the hourage obtaining, and with capitalization, T represents, observation whilst on tour is that actual observation obtains, and with lowercase, t represents.

As shown in Figure 6, the concrete steps of the inventive method are as follows:

Known geophone station number is n, and focus is expressed as A, B (now just by artificial experience, judging A is precision and the best point of reliability in all focus location), establishes the observation whilst on tour that focus A arrives geophone station to be

the observation whilst on tour that focus B arrives geophone station is model velocity is v, to being positioned such that of focus A, B:

(1) in arriving the observation whilst on tour (the observation whilst on tour of each focus is known conditions, is that the recognition technology by engineering obtains) of each geophone station, focus A finds minimum observation whilst on tour

if this geophone station is K, and get the poor of each observation whilst on tour and minimum value:

(A in formula represents focus A)

(2), within the scope of given Ω, according to formula (3), ask for each focus to the calculating whilst on tour T of each geophone station _i ^a, and get and calculate whilst on tour and the mistiming that arrives the calculating whilst on tour of geophone station K: ${\mathrm{\&Delta;T}}_i={T_i}^A-T_K^A$

(3) utilize full search method to find out formula

minimum value, the coordinate of its corresponding point is the coordinate of focus A; , by step (1) to (3), determined the coordinate of focus A;

(4) according to formula (6) error of calculation model { ε _i(i=1, n) } (by this step, having determined error, for the calculating of step (6));

(5) to focus B repeating step (1);

(6), within the scope of given Ω, according to formula (5), ask for each focus to calculating T hourage of each geophone station _i ^b, and get the calculating hourage of each geophone station and the mistiming of geophone station K: ${\mathrm{\&Delta;T}}_i={T_i}^B-T_K^B$

(7) repeating step (3), obtains the coordinate of B.In full search method, first suppose that certain is exactly some B point, so l _ivalue can try to achieve, in Ω scope, can seek out a lot of such postulated points, but make formula (1) value minimum only have one, this point is exactly real B point so.

Successively all focus are completed to location.

By two embodiment (theoretical model, a real data) below, verify effect of the present invention:

Embodiment 1:

Embodiment 1 adopts theoretical model to test.Fig. 1 is the model diagram in embodiment 1, and totally five layers, the speed of every layer is V1, V2, V3, V4, V5, place two focus A, B, wherein asterisk is focus A, and circle is focus B, A point is located at (1100,1200) position, B point is located at (950,1350) and locates, ground observation position is (10～1000) rice, in figure, shown in arrow, A is known point, and B is for needing the point of location.

Fig. 2 is the hourage (while being the observation arrival of A and B, step 1,2,3 is all used) observing, the curve that in Fig. 2, series 1 is ordered for A, and the curve that series 2 is ordered for B, (thick line in Fig. 2 (above) is series 2) chronomere is second.In table 1, be the location that utilizes the present invention to order to focus B under given different model, velocity variations only in model, the degree of depth that model is every layer is constant.As can be seen from Table 1, when rate pattern is correct (rate pattern 1 in table 1), focus B positioning error is 0, at rate pattern error individual layer (rate pattern 2 in table 1) 25% time, the focus B depth error 0 of location, lateral error is 5 meters, when rate pattern error is very large (rate pattern 3 in table 1 and model 4), the depth localization error of focus is 5 meters to the maximum, and lateral error is 20 meters to the maximum.By exploration means, actual rate pattern error can be controlled at 10% conventionally, and therefore, the precision of focus of the present invention location is very high.

Table 1

During concrete enforcement, can utilize c programming language, the (SuSE) Linux OS system of take realizes method of the present invention as platform, and trial effect is good; Provided by the invention is a kind of method to focus location, with programming language and operating system independent.

Embodiment 2:

Fig. 3 is the section of the focus A that observes of certain real data, two line of observation (arrangement modes of geophone station of different azimuth, the wave detector of totally two lines receives, article one, the line of observation refers to along arranging many wave detectors on a certain straight line) signal that obtains, wherein A point location aware is (3353126.0,338361.0,2145.1).

Fig. 4 is the section of the focus B that observes of certain real data, focus B Location-Unknown.

Fig. 5-1st, Fig. 3 is carried out to residual correction, and (residual correction is a kind of correction means in seismic prospecting, by mathematical method, be to eliminate time difference variation small in seismic trace, make the time curve more smooth) after hourage of picking up, Fig. 5-2nd, the hourage that Fig. 4 is carried out picking up after residual correction (be the hourage that Fig. 3 and Fig. 4 are carried out to pick up after residual correction in Fig. 5-1 and Fig. 5-2 time curve, be A (Fig. 3) in real data and the hourage of B (Fig. 4)), chronomere is millisecond.

Specifically, obtained the arrival whilst on tour of focus A and focus B, by the inventive method step 1～6, can obtain the location to focus B, its medium velocity is 4800m/s, by log data, is provided.

Utilize the inventive method as shown in table 2 to the result of focus B location:

	X	Y	Z
				Focus A	3353126.0	338361.0	2145.1
Focus B	3353126.0	386341.0	2125.0

Table 2

Embodiment 1 is theoretical model, rate pattern is known, focal point A and B are known, the observation whilst on tour of A and B is also known, and real data is in embodiment 2, the observation whilst on tour of A and B is known, focus A is known, but rate pattern and focus B are unknown, the location, position of B is object, meanwhile, supposes that B position and rate pattern are unknown in theoretical model, for the precision of test and check effect of the present invention and location, because the accuracy of real data cannot be checked.

Technique scheme is one embodiment of the present invention, for those skilled in the art, the invention discloses on the basis of application process and principle, be easy to make various types of improvement or distortion, and be not limited only to the described method of the above-mentioned embodiment of the present invention, therefore previously described mode is just preferred, and does not have restrictive meaning.

Claims (3)

1. the focus localization method of a release rate error effect, it is characterized in that: described method is by the position of known focus, ask for a velocity error model with velocity correlation, velocity error model is applied in objective function, then scan all possible source location, the coordinate that finds the point of the value minimum that makes objective function is exactly the coordinate of focus to be positioned.

2. the focus localization method of release rate error effect according to claim 1, is characterized in that: described in ask for one and be achieved in that with the velocity error model of velocity correlation

Be provided with n geophone station, get known focus A (x _a, y _a, z _a), by formula (3), calculating focus A is T to the calculating whilst on tour of each geophone station _i ^a,

${T_i}^A=\frac{{l_i}^A}{v}---\left(3\right)$

Wherein, T _i ^afor the calculating whilst on tour of focus A to i geophone station,

for the distance of focus A to i geophone station, v is velocity of propagation, and the velocity error model at i geophone station place is so:

${\mathrm{\&epsiv;}}_i=\frac{{T_i}^A}{{t_i}^A}---\left(6\right)$

Wherein

for focus A propagates into the observation whilst on tour of each geophone station, ε _ivelocity error ratio for i geophone station place.

3. the focus localization method of release rate error effect according to claim 2, it is characterized in that: described velocity error model is applied in objective function, then scan all possible source location, the coordinate that finds the point of the value minimum that makes objective function is exactly that the coordinate of focus to be positioned is achieved in that

For any one focus to be positioned, be handled as follows:

(1) the observation whilst on tour from this focus to each geophone station, find minimum observation whilst on tour, the corresponding geophone station of this minimum observation whilst on tour is made as geophone station K, then calculate this focus to the observation whilst on tour of each geophone station with this focus to the mistiming between the observation whilst on tour of geophone station K, this mistiming is to observe travel-time difference;

(2) in given scope, according to described velocity error model and formula (5), calculate each focus to the calculating hourage of each geophone station, and ask for each focus to the calculating whilst on tour of each geophone station with each focus to the mistiming between the calculating whilst on tour of geophone station K, this mistiming is calculating travel-time difference;

$T_i=\frac{l_i}{{\mathrm{v\&epsiv;}}_i}---\left(5\right)$

(3) take the quadratic sum of the difference between the calculating travel-time difference that observation travel-time difference that step (1) obtains and step (2) obtain is objective function, the institute of traversal in given range a little, makes the coordinate of point of the value minimum of described objective function be the coordinate of focus to be positioned.

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