CN103926618B - Based on cylinder matching 3-d seismic data set fracture detection method - Google Patents

Abstract

The present invention proposes a kind of method based on the fracture detection of cylinder matching 3-d seismic data set, it is specifically related to the fracture detection of 3-d seismic data set in oil-gas seismic exploration, is to rupture the supplementary of detection technique for the most commonly used earthquake curvature attributes and coherent body and improve.This method is through strict mathematical derivation, based on cylinder matching, by asking for of cylinder directrix curvature variation, on the basis of conventional method, disclose the other fracture of even lower level further, including three steps: (1) utilizes cylinder straight edge line fit fracture to move towards；(2) along the cylinder directrix matching of plane of disruption tendency；(3) calculating of cylinder directrix curvature variation.The present invention has important guiding value to oil-gas exploration target prediction.Compared with conventional method, this method has the advantage that the fracture portraying less rank；Can more accurately indicate the position of fracture；The interference that fracture is characterized by the geologic body such as fold, fornix can be suppressed.

Description

Based on cylinder matching 3-d seismic data set fracture detection method

Technical field

The invention belongs to oil gas field seismic exploration technique field, be specially three-dimensional post-stack seismic data body rupture System and become Picture, the meticulous depiction of the least turn-off fracture.

Background technology

For post-stack seismic data body, Acceleration Algorithm in Seismic Coherence Cube calculates and earthquake curvature attributes has been used as carving for many years Draw fracture, the key technology of prediction fracture.Coherent body characterizes fracture from curvature attributes from different sides, and coherent body passes through waveform Similarity find out the discontinuity at interface, and then detection of run-out, curvature is the most directly carved by the geometry of fault interface Draw fracture.By a large amount of earthquake readouts, contrast, find that some vertical turn-offs are less, be particularly difficult to from seismic profile Directly observing or easy unheeded little fracture, curvature attributes is portrayed the finest.Earthquake curvature is to seismic reflection circle Face carries out Quadratic Surface Fitting, then asks for curvature of curved surface.But after subsurface interface fracture, its breaking part is in seismic reflection circle Show as a pair arch and recessed juxtaposed assemblage characteristic on face, the most then show as cylinder feature, rather than quadratic surface (is schemed 1), the bus of cylinder is parallel to fracture direction, and the directrix of cylinder is along the tendency of the plane of disruption.The present invention is from self geometry of the plane of disruption Feature is set out, and utilizes cylinder fit fracture face, and calculates the curvature variation of cylinder directrix.This method can more finely and accurately Portray fracture, and the fracture of less rank can be disclosed, provide necessary underground for oil-gas exploration target prediction, Analysis of Hydrocarbon Accumulation etc. Fracture information.

Summary of the invention

It is an object of the invention to provide a kind of effective, from fault interface self geometric properties, based on cylinder plan Close the method extracting 3-d seismic data set fracture information, improve fracture and characterize precision, can be oil-gas exploration target prediction And Analysis of Hydrocarbon Accumulation etc. provides necessary fracture information.

To achieve these goals, the invention provides a kind of based on cylinder matching, and extract cylinder directrix Curvature varying The method of rate information carrys out meticulous depiction fracture, comprises the following steps:

Step 1: cylinder straight edge line matching.Initially setting up coordinate system as shown in Figure 2, x, y-axis are respectively parallel to seismic survey lines And the direction in road, z is perpendicular to x/y plane, and sampled point spacing is set to 1, and zero is positioned at central point β₀Underface, is considered as It it is the central point projection at x/y plane.Adjacent 3 × 3 sampling points are numbered into α_i、β_i、γ_i, wherein i=-1,0,1, accordingly Vertical coordinate be:Wherein i=-1,0,1, as in figure 2 it is shown, p, q are match value to be asked.Special according to cylinder Levy, after sampled point in figure is carried out least square fitting, ask p, q by equation below group:

$\left\{\begin{array}{c}{6\mathrm{ap}}^3+p(12a+6c-\underset{i=-1}{\overset{1}{\mathrm{\Σ}}}(Z_{{\mathrm{\α}}_i}+Z_{{\mathrm{\γ}}_i}))+(Z_{{\mathrm{\α}}_{-1}}-Z_{{\mathrm{\α}}_1}+Z_{{\mathrm{\γ}}_1}+Z_{{\mathrm{\γ}}_{-1}})=0---\left(1\right)\\ q=\frac{\underset{i=-1}{\overset{1}{\mathrm{\Σ}}}{Z}_{{\mathrm{\α}}_i}-\underset{i=-1}{\overset{1}{\mathrm{\Σ}}}{Z}_{{\mathrm{\γ}}_i}-6\mathrm{bp}}{6}---\left(2\right)\end{array}\right.$

Wherein

$\left\{\begin{array}{c}a=\frac{Z_{{\mathrm{\β}}_{-1}}+Z_{{\mathrm{\β}}_1}}{2}-Z_{{\mathrm{\β}}_0}\\ b=\frac{Z_{{\mathrm{\β}}_1}-Z_{{\mathrm{\β}}_{-1}}}{2}\\ c=Z_{{\mathrm{\β}}_0}\end{array}\right.---\left(3\right)$

Formula (1) is a simple cubic equation, can use the red formula of card or Sheng gold formula to try to achieve p value, recycles formula (2), Obtain q value.P is real number, the most only retains the real root of analytic solutions, when there being multiple real root, determines p, q end value with following formula:

Wherein

$\left\{\begin{array}{c}{z}_1\left(x\right)=a{(x-p)}^2+b(x-p)+c+q\\ z_{-1}\left(x\right)=a{(x+p)}^2+b(x+p)+c-q\end{array}\right.---\left(5\right)$

When meetingTime minimum, p, q are required.

Step 2: cylinder directrix matching.Adjacent 3 road sampling points are numbered for: first is α_i, wherein i=-3 ,-2 ,- 1,0,1,2, second is β_i, wherein i=-2, the-1,0,1,2, the 3rd road is γ_i, wherein i=-2 ,-1,0,1,2,3；To first Road and the 3rd road adjacent spots carry out linear interpolation and obtain two groups of sampling points, are respectivelyWherein i=-2 ,-1,0,1,2； Sampling pointβ_i、Vertical coordinate be respectivelyWherein i=-2 ,-1,0,1,2；As it is shown on figure 3, x, y-axis are respectively Being parallel to the direction in seismic survey lines and road, z-axis is perpendicular to x/y plane, puts β centered by zero₀, using cubic curve as post Face directrix matching sampling pointβ_i、Wherein i=-2 ,-1,0,1,2, at plane y=1, y=0, y=-1, equation is as follows:

$\left\{\begin{array}{c}{z}_1\left(x\right)=a{(x-p)}^3+b{(x-p)}^2+c(x-p)+d+q\\ z\left(x\right)={\mathrm{ax}}^3+{\mathrm{bx}}^2+\mathrm{cx}+d\\ z_{-1}\left(x\right)=a{(x+p)}^3+b{(x+p)}^2+c(x+p)+d-q\end{array}---\left(6\right)\right.$

They are the results after same curve mutually translates.A, b, c are as follows to utilize method of least square to determine:

$\left\{\begin{array}{c}a=\frac{{-Z}_{-2}+{2Z}_{-1}-{2Z}_1+Z_2}{36}\\ b=\frac{{2Z}_{-2}-Z_{-1}-{2Z}_0-Z_1+{2Z}_2}{42}\\ c=\frac{Z_{-2}-{8Z}_{-1}+{8Z}_1-Z_2}{36}\end{array}\right.---\left(7\right)$

Wherein

$Z_i=Z_{{\widehat{\mathrm{\α}}}_i}+Z_{{\mathrm{\β}}_i}+Z_{{\widehat{\mathrm{\γ}}}_i}(i=-2,-\mathrm{1,0,1,2})---\left(8\right)$

Step 3: cylinder directrix curvature variationCalculate.Algorithm is as follows:

$\stackrel{\·}{\mathrm{\κ}}=\frac{6a+{6\mathrm{ac}}^2-{12b}^{2}c}{{(1+c^2)}^3}---\left(9\right)$

Fig. 4 is a quasi-curvature of a curve and curvature variation.Can be seen that this method is portrayed compared with tradition Curvature Methods Fracture has obvious advantage.Noticing that the flex point of matched curve exactly corresponds to the center of the plane of disruption, its curvature has One maximum and a minima, symmetrical about flex point, and curvature variation only one of which extreme value, can be obvious by its amplitude Finding out, it is more sensitive to fracture, and is explicitly indicated plane of disruption center, and therefore curvature variation is when portraying fracture ten Divide effectively.

In theory, curvature variation can be completely eliminated the impact that fracture is characterized by the geological structure of tool quadratic surface feature, Such as fold turn end and dome structure top.But actual geological condition seldom has preferable quadratic surface, the most above-mentioned structure Make and tend not to be completely eliminated, but to its compacting in various degree.

Accompanying drawing explanation

Fig. 1. fracture model and matching schematic diagram, the bus of matching cylinder is straight line, is parallel to fracture direction, post Face directrix is a cubic curve, along the tendency of the plane of disruption.

Fig. 2. cylinder straight edge line matching schematic diagram, the coordinate of the sequence number of each sampled point and fractional-sample point is as shown in FIG..

Fig. 3. cylinder directrix matching schematic diagram, the sequence number of each sampled point as it can be seen, middle 9 sampled points are identical with Fig. 2, Need owing to calculating, respectively increase by 4 sampled points at its two ends.

Fig. 4. disconnect curvature and the curvature variation comparison diagram of the matched curve of bed boundary.

Fig. 5. different calculating sampling points corresponding to fracture direction.

Fig. 6. (a) crosses the seismic profile of the different section of same fracture；B () crosses the seismic profile of same fold difference section.

Fig. 7. curvature and curvature variation horizon slice comparison diagram, AA '-EE ' is used as the contrast that fracture is portrayed, FF '-HH ' The display curvature variation suppression to fold.

Detailed description of the invention

Below with platform area, western part, tower Zhong Bei slope geological data, in conjunction with accompanying drawing, specific implementation method of the present invention is made into The detailed description of one step.The geological data bin used is 25m × 25m, and time domain 2ms is sampled, and concrete Ceng Weiweigai district is difficult to understand The top of pottery ware well compactness carbonate rock.Owing to well compactness superstratum is siliciclastic rock, big natural impedance official post Obtain the reflection of this interface clear, readily identified, therefore extract seismic properties along this reflecting layer, it is possible to preferably contrast.Specifically Step is as follows:

The first step: determine fracture direction by segment of a cylinder matching

In view of all possible fracture direction, complete whole calculating (Fig. 5) with four groups of sampled points.Only need to investigate often group Spot fitting result, i.e. minimumThe actual trend of value correspondence fracture.Due to calculate involved by several for seismic reflector What attribute, therefore by traditional method, such as waveform similarity, it is ensured that in Fig. 5, sampling optimization is in same reflection interface.According to Fig. 2 The coordinate system set up, calculates p, q value according to formula (1)-(5).

Second step: determine cubic fit curve by cylinder directrix matching

Utilize the first step to calculate p, q value, then determine its coordinate according to each sampling point position of Fig. 3, then pass through formula (6)-(8), calculate a, b, c.

3rd step: calculate cylinder directrix curvature variation

Utilize a, b, c value that second step calculates, calculate curvature variation further according to formula (9).

In order to prove the superiority of the present invention, it is compared with curvature attributes.As shown in Figure 6 a, the earthquake of black line mark Axis of reflection is corresponding to the top of this district's Ordovician system well compactness carbonate rock, and 5 section AA '-EE ' are corresponding to same fracture Different piece, its plane distribution is corresponding to position shown in Fig. 7 middle conductor AA '-EE '.From Fig. 6 a indicated by arrow from the point of view of, same Bar breaks at the vertical turn-off of different section and is not quite similar.AA ', CC ' and DD ' show as bigger turn-off, and BB ' and EE ' turn-off are relatively Little.The horizon slice of curvature and curvature variation is as shown in Figure 7.As seen from the figure, curvature and curvature variation can well be carved Draw relatively large turn-off, but when turn-off is less, only curvature variation can clearly characterize fracture (see BB ' in Fig. 7 and EE '), say, that curvature variation can portray the fracture that turn-off is less.

Look next at this method suppression to fold.In Fig. 6 b, 3 section FF '-HH ' are corresponding to same fold not Same part, its plane distribution is corresponding to position shown in Fig. 7 middle conductor FF '-HH '.As shown in Figure 6 b, arrow indicates turning of fold Folding end.This turn end is clear and legible (Fig. 7 a) on curvature attributes, but has fogged on curvature variation (Fig. 7 b), this Just explanation is for having the geological interface of quadratic surface feature, and curvature variation attribute is not to make it strengthen, and has to a certain degree on the contrary Compacting.

In sum, this method is that fracture depicting method in the past is supplemented and improved.To fracture sign have more for Property, and the fracture of even lower level other little turn-off can be characterized.

Claims (2)

1. 3-d seismic data set based on a cylinder matching fracture detection method, it is characterised in that comprise the following steps:

Step 1: be first fitted cylinder straight edge line, makes x, y-axis be respectively parallel to the direction in seismic survey lines and road, and z is vertical In x/y plane, sampled point spacing is 1；Adjacent 3 × 3 sampling points are numbered into α_i、β_i、γ_i, wherein i=-1,0,1, accordingly Vertical coordinate be:Wherein i=-1,0,1；P, q are match value to be asked, and ask for by equation below group:

$\left\{\begin{array}{c}6{\mathrm{ap}}^3+p(12a+6c-\underset{i=-1}{\overset{1}{\Σ}}(Z_{{\mathrm{\α}}_i}+Z_{{\mathrm{\γ}}_i})\]+(Z_{{\mathrm{\α}}_{-1}}-Z_{{\mathrm{\α}}_1}+Z_{{\mathrm{\γ}}_1}+Z_{{\mathrm{\γ}}_{-1}})=0\\ q=\frac{\underset{i=-1}{\overset{1}{\Σ}}{Z}_{{\mathrm{\α}}_i}-\underset{i=-1}{\overset{1}{\Σ}}{Z}_{{\mathrm{\γ}}_i}-6bp}{6}\end{array}\right.,$

Wherein

$\left\{\begin{array}{c}a=\frac{Z_{{\mathrm{\β}}_{-1}}+Z_{{\mathrm{\β}}_1}}{2}-Z_{{\mathrm{\β}}_0}\\ b=\frac{Z_{{\mathrm{\β}}_1}-Z_{{\mathrm{\β}}_{-1}}}{2}\\ c=Z_{{\mathrm{\β}}_0}\end{array}\right.;$

Step 2: be fitted cylinder directrix, adjacent 3 road sampling points are numbered: first, α_i, wherein i=-3 ,-2 ,-1,0,1, 2, second, β_i, wherein i=-2, the-1,0,1,2, the 3rd road, γ_i, wherein i=-2 ,-1,0,1,2,3；To first and the 3rd Road adjacent spots carries out linear interpolation and obtains two groups of sampling points, is respectivelyWherein i=-2 ,-1,0,1,2；Sampling pointβ_i、 Vertical coordinate be respectivelyWherein i=-2 ,-1,0,1,2；X, y-axis is made to be respectively parallel to seismic survey lines and road Direction, z-axis is perpendicular to x/y plane, centered by zero put β₀, using cubic curve as cylinder directrix matching sampling pointβ_i、Wherein i=-2 ,-1,0,1,2, at plane y=1, y=0, y=-1, equation is as follows:

$\left\{\begin{array}{c}{z}_1\left(x\right)=a{\left(x-p\right)}^3+b{\left(x-p\right)}^2+c(x-p)+d+q\\ z\left(x\right)=a{x}^3+b{x}^2+cx+d\\ z_{-1}\left(x\right)=a{\left(x+p\right)}^3+b{\left(x+p\right)}^2+c(x+p)+d-q\end{array}\right.,$

Wherein

$\left\{\begin{array}{c}a=\frac{-Z_{-2}+2Z_{-1}-2Z_1+Z_2}{36}\\ b=\frac{2Z_{-2}-Z_{-1}-2Z_0-Z_1+2Z_2}{42}\\ C=\frac{Z_{-2}-8Z_{-1}+8Z_1-Z_2}{36}\end{array}\right.,$

Wherein

$Z_i=Z_{{\widehat{\mathrm{\α}}}_i}+Z_{{\mathrm{\β}}_i}+Z_{{\widehat{\mathrm{\γ}}}_i},(i=-2,-1,0,1,2);$

Step 3: alignment line curvature variation is asked for, makes it beAlgorithm is as follows:

$\stackrel{\·}{\mathrm{\κ}}=\frac{6a+6{\mathrm{ac}}^2-12b^{2}c}{{(1+c^2)}^3}.$

A kind of 3-d seismic data set based on cylinder matching fracture detection method, its feature exists In, simple cubic equation is solved by step 1, when its root p exists multiple real root, determines p, q end value with following formula:

Wherein

$\left\{\begin{array}{c}{z}_1\left(x\right)=a{\left(x-p\right)}^2+b(x-p)+c+q\\ z_{-1}\left(x\right)=a{\left(x+p\right)}^2+b(x+p)+c-q\end{array}\right.,$

When meetingTime minimum, p, q are required.