CN103344998A - Method for wavelet transform anomalousness extraction in transient electromagnetic data - Google Patents

Abstract

The invention relates to the technical field of geophysical exploration, in particular to a method for wavelet transform anomalousness extraction in transient electromagnetic data. According to the method, a background field in the transient electromagnetic data can be eliminated, and needed data of an anomalous field are extracted. The method includes the steps that (1) interpolation is carried out on data in X and Y directions according to regular nets; (2) a db4 wavelet basis is adopted to carry out disintegration on a j measuring line in any one direction; (3) multilayer approximate signals are reconstructed; (4) multilayer detail signals are reconstructed; (5) the detail signals are synthesized; (6) whether the above steps are carried out on all measuring lines in the direction or not is judged; (8) whether a drawing result is welcomed or not is judged, whether a background value has been eliminated or not is judged, and if the effect is not good, the direction is modified, and the steps from (2)-(8) are repeated; (9) whether detail signals in two directions need to be synthesized or not is judged, if the detail signals in the two directions need to be synthesized, the detail signal are synthesized according to a following equation, then the detail signals after being synthesized are utilized to draw, the whole process is finished, and if the detail signals in the two directions do not need to be synthesized, the whole process is directly finished.

Description

A kind of transient electromagnetic data wavelet transformation extracts unusual method

One, technical field:

The present invention relates to the geophysical exploration technology field, be specifically related to a kind of transient electromagnetic data wavelet transformation and extract unusual method.

Two, background technology:

The apparent resistivity result of transient electromagnetic; often owing to some complicated geology reason or environment reason; apparent resistivity is distributed the situation very relevant with the electrical background of geology occur; in this case; the apparent resistivity that the explanation personnel are concerned about can be buried unusually in the electrical background information in large-area stratum; can not get embodying intuitively, therefore, need the outstanding unusual solution of research.

Three, summary of the invention:

The present invention provides a kind of transient electromagnetic data wavelet transformation to extract unusual method in order to solve the weak point in the above-mentioned background technology, and the ambient field that it can be eliminated in the transient electromagnetic data extracts the anomalous field data that need.

For achieving the above object, the technical solution used in the present invention is: a kind of transient electromagnetic data wavelet transformation

Extract unusual method, it is characterized in that: described method step is:

(1), data is pressed the regular grid interpolation along X, Y-direction;

(2), along either direction to

The bar survey line adopts the db4 wavelet basis to decompose;

(3), reconstruct multilayer approximate signal;

(4), reconstruct multilayer detail signal;

(5), synthetic detail signal;

(6), judge whether all surveys line of this direction are all finished above step, as do not have, change survey line, repeating step (2)-(6);

(7), draw with the detail signal data that newly obtain;

(8), judge whether the drawing result is satisfied with, and whether has eliminated background value, as think poor effect, revise direction, repeat (2)-(8);

(9), judge whether that needs synthesize the detail signal of both direction, as needs, according to the synthetic detail signal of following formula

In the formula,

,

Represent a certain measuring point respectively along directions X and the detail signal that extracts along Y-direction, again with synthetic back detail signal

Draw, finish whole flow process, as not needing, directly finish whole flow process.

Compared with prior art, advantage and effect that the present invention has are as follows: the present invention can be decomposed into approximate signal and detail signal by with small wave converting method data being decomposed, again the mode that detail section is synthesized, reach and eliminate the ambient field influence, highlight the purpose of anomalous field.

Four, description of drawings:

Fig. 1 is the general flow chart of the embodiment of the invention;

Fig. 2 looks the degree of depth-apparent resistivity original section figure for the transient electromagnetic of the present invention after calculating;

Fig. 3 extracts the comparison diagram of sectional view unusually for the present invention.

Five, embodiment:

The present invention is described in detail below in conjunction with embodiment and Figure of description.

Performing step of the present invention is (referring to Fig. 1):

(1), data is pressed the regular grid interpolation along X, Y-direction;

(2), along either direction (as directions X) to

The bar survey line adopts the db4 wavelet basis to decompose;

(3), reconstruct multilayer (as 5 layers) approximate signal;

(4), reconstruct multilayer (as 5 layers) detail signal;

(5), synthetic detail signal;

(6), judge whether all surveys line of this direction are all finished above step, as do not have, change survey line, repeating step (2)-(6);

(7), draw with the detail signal data that newly obtain;

(8), judge whether the drawing result is satisfied with, and whether has eliminated background value, as think poor effect, revise direction (as changing Y into), repeat (2)-(8);

(9), judge whether that needs synthesize the detail signal of both direction, as needs, according to the synthetic detail signal of following formula

In the formula,

,

Represent a certain measuring point respectively along directions X and the detail signal that extracts along Y-direction, again with synthetic back detail signal Draw, finish whole flow process, as not needing, directly finish whole flow process.

Be example explanation effect of the present invention below with the measured data:

As can be seen from Figures 2 and 3, owing to some complicated geology reasons, make the apparent resistivity distribution overall trend on Fig. 2 very even, exist a low-resistance unusual at horizontal range 30m place, but this all has reflection (isoline in the empty frame of black is recessed) unusually from 50m to 90m on depth direction, be difficult to accurately judge unusual buried depth, after unusual the extraction, unusual (the closed circle of isoline in the empty frame of black) that Fig. 3 reflects is positioned at horizontal range 30m, about buried depth 70m, this and the known actual position, sky tunnel of adopting coincide fine, black is low value among the figure, and white is high value.

Claims (1)

1. a transient electromagnetic data wavelet transformation extracts unusual method, and it is characterized in that: described method step is:

(1), data is pressed the regular grid interpolation along X, Y-direction;

(2), along either direction to The bar survey line adopts the db4 wavelet basis to decompose;

(3), reconstruct multilayer approximate signal;

(4), reconstruct multilayer detail signal;

(5), synthetic detail signal;

(6), judge whether all surveys line of this direction are all finished above step, as do not have, change survey line, repeating step (2)-(6);

(7), draw with the detail signal data that newly obtain;

(8), judge whether the drawing result is satisfied with, and whether has eliminated background value, as think poor effect, revise direction, repeat (2)-(8);

(9), judge whether that needs synthesize the detail signal of both direction, as needs, according to the synthetic detail signal of following formula

In the formula,

, Represent a certain measuring point respectively along directions X and the detail signal that extracts along Y-direction, again with synthetic back detail signal

Draw, finish whole flow process, as not needing, directly finish whole flow process.

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