CN102236108A - Three-dimensional terrain correcting method for magnetic surface - Google Patents

Abstract

The invention provides a three-dimensional terrain correcting method for a magnetic surface in geophysical exploration. The method comprises the following steps: acquiring a surface and stratum magnetisability distribution grid data; constructing a three-dimensional terrain combined cylinder model to form a vertical magnetic upright square cylinder; calculating a magnetic anomaly effect value of each magnetic terrain square cylinder for the vertical magnetic anomaly generated by all upright cylinders with corresponding magnetisability to a survey point; taking the absolute values of the magnetic anomaly effect values of node elevations of the survey point, and summing the absolute values; and adding a magnetic terrain correction value of the calculating point to data of a corresponding point of exploration to acquire corrected magnetic anomaly data. By the method, the magnetic anomaly distortion influenced by magnetic terrain is comprehensively corrected, the distorted magnetic anomaly value on a topographic relief position is raised and recovered, the reflection of magnetic anomaly to an underground magnetic target is more accurate, the magnetic anomaly becomes continuous, zonation is remarkably strengthened, and the mountain magnetic exploration information processing accuracy can be improved.

Description

A kind of magnetic landscape dimensional topography correcting method

Technical field

The invention belongs to geophysical exploration method, is the data processing method of a kind of ground magnetic exploration.

Background technology

Magnetic exploration is the method for exploration based on subsurface formations rock magnetism difference, utilizes magnetometer observational record changes of magnetic field, obtains subsurface geologic structures through data processing.Existing petroleum industry standard (" ground magnetometer survey technical regulation (SY/T5771-2004) ") has provided the method and the standard of magnetic exploration DATA PROCESSING, wherein not requiring to carry out the magnetic topographic correction handles, also do not have magnetic landscape topographic correction method, the distortion effects that makes landform cause can not obtain proofreading and correct.

Above-mentioned treatment technology still can be suitable in the low precision stage, but in the high precision magnetic exploration, the landform of mountain region magnetic survey particularly, and its harmful effect can not be ignored.Utilize magnetic exploration songization quadratic method to handle mountain area magnetic anomalies data at present; but these class methods belong to Qu Huaping; be about to relief surface and be converted to list processing (LISP) flatly; do not consider the magnetic effect of landform magnetic; do not calculate the measuring point magnetic anomaly distortion that the magnetic landform produces; the songization quadratic method is not a magnetic topographic correction method, can not get high-precision magnetic exploration effect.

Summary of the invention

The purpose of this invention is to provide a kind of magnetic anomaly distortion that three-dimensional magnetic landform causes of proofreading and correct, can reflect the magnetic landscape dimensional topography correcting method of the magnetic source regularity of distribution and numerical value.

The present invention realizes by following steps:

1) magnetic exploration is carried out in the work area, the measuring point magnetic survey of acquisition, change utmost point magnetic anomaly, work area and extend out district's landform altitude grid, geologic map and stratum magnetic statistics;

2) give the magnetic susceptibility value according to stratum magnetic susceptibility with corresponding stratum in the geologic map, obtain stratum, face of land magnetic susceptibility distribution grid data.

Step 2) stratum, described face of land magnetic susceptibility distribution grid data is the panel data grid.

3) according to the relative height relation of each node elevation data value of terrain mesh, make up dimensional topography combination type cylinder models with the calculation level height value;

The described structure three-dimensional array of step 3 type cylinder models is that the landform node grid that height value is higher than calculation level is the positive upright cylinder that makes progress, the landform node grid that height value is lower than calculation level constitutes negative downward upright body, and the center of each main body is each landform node.

4) according to stratum, the face of land magnetic susceptibility grid node value of each cylinder corresponding flat node location in the dimensional topography combination cylinder, give the cylinder magnetization and form the upright square body of perpendicular magnetization;

The upright square body magnetization of the described perpendicular magnetization of step 4) is (1+Q) * k*T ₀,

In the formula: Q is a remanent magnetism sense magnetic ratio, surveys in the district and can be taken as constant, and k is the magnetic susceptibility value of corresponding node, T ₀For surveying the terrestrial magnetic field mean value in the district, be constant,

Above-mentioned remanent magnetism sense magnetic is 0.1-2.0 than Q.

5) according to the position of calculation level, the upright cylinders with corresponding magnetic susceptibility all in the computer capacity for the vertical magnetic anomaly that measuring point produces, is calculated the magnetic anomaly effect value of each magnetic landform square body by the upright square body magnetic anomaly of spatial domain perpendicular magnetization computing formula;

The described computer capacity of step 5) is 30-50km.

The upright square body magnetic anomaly of spatial domain perpendicular magnetization computing formula in the step 5) is:

$\mathrm{\Δ}{T}_{\⊥}=(-{\mathrm{\μ}}_0/4\mathrm{\π})\·j\·{\∫\∫\∫}_v\frac{3{(\mathrm{\ξ}-x)}^2-R^2}{R^3}\mathrm{dxdydz}+{\∫\∫\∫}_v\frac{3{(\mathrm{\η}-y)}^2-R^2}{R^3}\mathrm{dxdydz}$

Wherein: the calculation level coordinate be (x, y, z), the coordinate of ground annular volume branch be (ξ,

ζ),

μ ₀: permeability of vacuum.

6) will be higher than the magnetic anomaly effect value of node elevation of measuring point and the magnetic anomaly effect value that is lower than the measuring point elevation all takes absolute value, and, obtain the magnetic topographic correction value of this calculation level with the magnetic effect absolute value summation of each terrain mesh node in all computer capacities for calculation level.

7) each is calculated the change utmost point magnetic anomaly data addition of magnetic topographic correction value with the corresponding point of step 1) exploration acquisition of measuring point, obtain the magnetic anomaly data behind the magnetic topographic correction.

The present invention is comprehensively proofreaied and correct the magnetic anomaly distortion that is subjected to the magnetic influence of topography; field data is handled and is shown; behind the topographic correction; the magnetic anomaly value of the distortion at topographic relief place obtains raising and recovers; magnetic anomaly is more accurate to the reflection of underground magnetic target; magnetic anomaly becomes continuously, tapability obviously strengthens, and can improve mountain region magnetic exploration Data Processing precision.

Description of drawings

Fig. 1 is landform altitude figure (isoline is apart from 100m);

Fig. 2 is that (isoline is apart from 50*10 for the magnetic susceptibility distribution plan ^-5SI);

Fig. 3 is magnetic topographic correction value figure (isoline is apart from 20nT);

Fig. 4 is the change utmost point MAM (isoline is apart from 100nT) before the magnetic topographic correction;

Fig. 5 is the magnetic anomaly data behind the magnetic topographic correction;

Fig. 6 is magnetic anomaly comparison diagram before and after correct in work area of the present invention (solid line changes preceding magnetic anomaly for ground, and dotted line changes the back magnetic anomaly for ground) (isoline is apart from 20nT).

Embodiment

Before the three-dimensional magnetic topographic correction of the invention process, the related data that needs to prepare comprises that exploration work area measuring point extends out the landform altitude grid data (Fig. 1) of computer capacity (40km), actual measurement magnetic force measuring point coordinate data (x, y, h), survey district's stratum magnetic susceptibility and measure statistical form and geologic map, change utmost point magnetic anomaly data, these data are data that conventional magnetic exploration all possesses.

Three-dimensional magnetic topographic correction method of work is implemented as follows:

1) reads in work area utmost point magnetic anomaly (Fig. 4), landform altitude grid (Fig. 1);

2) give the magnetic susceptibility value according to stratum, work area magnetic susceptibility with corresponding stratum in the geologic map, obtain stratum, face of land magnetic susceptibility distribution grid data (Fig. 2).

3) read in the calculation level coordinate (x y) and elevation (h), compares each node elevation data value of terrain mesh and calculation level height value, the node elevation difference that is higher than the calculation level elevation on the occasion of, the node elevation difference that is lower than the calculation level elevation is a negative value;

4) calculate the magnetization of respectively calculating cylinder corresponding flat node location: j=(1+Q) KT ₀, T ₀: local geomagnetic field intensity (getting 55400.0); The K-rock susceptibility; Q: the surplus sense of rock magnetism is than (getting 0.5).

5) adjust the distance in the calculation level 40km all landform altitude cylinder for measuring point (x, y, h) vertical magnetic anomaly of Chan Shenging:

$\mathrm{\Δ}{T}_{\⊥}=(-{\mathrm{\μ}}_0/4\mathrm{\π})\·j\·{\∫\∫\∫}_v\frac{3{(\mathrm{\ξ}-x)}^2-R^2}{R^3}\mathrm{dxdydz}+{\∫\∫\∫}_v\frac{3{(\mathrm{\η}-y)}^2-R^2}{R^3}\mathrm{dxdydz}$

Wherein: the calculation level coordinate be (x, y, z), the coordinate of ground annular volume branch be (ξ,

ζ),

μ ₀: permeability of vacuum.

6) the magnetic anomaly effect value with each node elevation cylinder takes absolute value, and summation, obtains the magnetic topographic correction value of this calculation level.All measuring points are calculated, obtain the magnetic topographic correction value (Fig. 3) of each measuring point in work area.

7) each is calculated change utmost point magnetic anomaly (Fig. 4) addition of magnetic topographic correction value (Fig. 3) with the corresponding point of measuring point, obtain the magnetic anomaly data (Fig. 5) behind the magnetic topographic correction.

Can know by Fig. 6 and to see the forward and backward effect comparison of three-dimensional magnetic topographic correction.

Claims (7)

1. magnetic landscape dimensional topography correcting method is characterized in that realizing by following steps:

1) magnetic exploration is carried out in the work area, the measuring point magnetic survey of acquisition, change utmost point magnetic anomaly, work area and extend out district's landform altitude grid, geologic map and stratum magnetic statistics;

2) give the magnetic susceptibility value according to stratum magnetic susceptibility with corresponding stratum in the geologic map, obtain stratum, face of land magnetic susceptibility distribution grid data.

3) according to the relative height relation of each node elevation data value of terrain mesh, make up dimensional topography combination type cylinder models with the calculation level height value;

4) according to stratum, the face of land magnetic susceptibility grid node value of each cylinder corresponding flat node location in the dimensional topography combination cylinder, give the cylinder magnetization and form the upright square body of perpendicular magnetization;

5) according to the position of calculation level, the upright cylinders with corresponding magnetic susceptibility all in the computer capacity for the vertical magnetic anomaly that measuring point produces, is calculated the magnetic anomaly effect value of each magnetic landform square body by the upright square body magnetic anomaly of spatial domain perpendicular magnetization computing formula;

6) will be higher than the magnetic anomaly effect value of node elevation of measuring point and the magnetic anomaly effect value that is lower than the measuring point elevation all takes absolute value, and, obtain the magnetic topographic correction value of this calculation level with the magnetic effect absolute value summation of each terrain mesh node in all computer capacities for calculation level;

7) each is calculated the change utmost point magnetic anomaly data addition of magnetic topographic correction value with the corresponding point of step 1) exploration acquisition of measuring point, obtain the magnetic anomaly data behind the magnetic topographic correction.

2. magnetic landscape dimensional topography correcting method according to claim 1 is characterized in that step 2) magnetic susceptibility distribution grid data in stratum, the described face of land is the panel data grid.

3. magnetic landscape dimensional topography correcting method according to claim 1, it is characterized in that the described structure three-dimensional array of step 3) type cylinder models is that the landform node grid that height value is higher than calculation level is the positive upright cylinder that makes progress, the landform node grid that height value is lower than calculation level constitutes negative downward upright body, and the center of each main body is each landform node.

4. magnetic landscape dimensional topography correcting method according to claim 1 is characterized in that the upright square body magnetization of the described perpendicular magnetization of step 4) is (1+Q) * k*T ₀,

In the formula: Q is a remanent magnetism sense magnetic ratio, surveys in the district and can be taken as constant, and k is the magnetic susceptibility value of corresponding node, T ₀For surveying the terrestrial magnetic field mean value in the district, be constant,

5. according to claim 1 or 4 described magnetic landscape dimensional topography correcting methods, it is characterized in that above-mentioned remanent magnetism sense magnetic is 0.1-2.0 than Q.

6. magnetic landscape dimensional topography correcting method according to claim 1 is characterized in that the described computer capacity of step 5) is 30-50km.

7. magnetic landscape dimensional topography correcting method according to claim 1 is characterized in that the upright square body magnetic anomaly of the spatial domain perpendicular magnetization computing formula in the step 5) is:

$\mathrm{\Δ}{T}_{\⊥}=(-{\mathrm{\μ}}_0/4\mathrm{\π})\·{j\·\∫\∫\∫}_v\frac{3{(\mathrm{\ξ}-x)}^2-R^2}{R^3}\mathrm{dxdydz}+{\∫\∫\∫}_v\frac{3{(\mathrm{\η}-y)}^2-R^2}{R^3}\mathrm{dxdydz}$

Wherein: the calculation level coordinate be (x, y, z), the coordinate of ground annular volume branch be (ξ,

, ζ),

μ ₀: permeability of vacuum.

Images