APPARATUS AND METHOD FOR IMAGING SUBSURFACE STRUCTURE

• US 20110299361A1
• Filed: 02/17/2010
• Published: 12/08/2011
• Est. Priority Date: 02/17/2009
• Status: Abandoned Application

• Current Assignee: Shin's Geophysics
• Original Assignee: Shin's Geophysics
• Inventors: Shin, Changsoo
• Application Number:
  US13/201,550
• Publication Number:
  US 20110299361A1
• Time in Patent Office: Days
• US Class Current: 367/21
• CPC Class Codes: G01V 1/28 Processing seismic data, e.g. for interpretation or for event detection G01V1/48 takes precedence
• CPC Class Codes: G01V 2210/66 Subsurface modeling

Abstract

The present invention relates to an imaging technique for modeling a subsurface structure through waveform inversion in the Laplace domain. According to the present invention, a source equivalent to the real source is calculated. The equivalent source is at least one source arranged on a virtual grid of the area to be measured, and the virtual grid has a large size which cannot be employed as the location of the real source in conventional techniques. The equivalent source has a vector obtained by multiplying an analytical solution vector and an impedance matrix of a Laplace domain wave equation, wherein said analytical solution vector is obtained from the analytical solution of a Laplace domain wave equation in a homogeneous half space by the real source.

Claims

1. An apparatus for imaging a subsurface structure, comprising:

an equivalent source calculation unit to obtain an equivalent source that is equivalent to a real source, wherein the equivalent source is at least one virtual source located at one of points defining virtual grids in an area to be measured; and

a subsurface structure-modeling unit to obtain modeling parameter data about the subsurface structure, by performing Laplace-domain waveform inversion on a plurality of seismic signals acquired by a plurality of receivers arranged on the virtual grids in the area to be measured, based on a vector of the equivalent source.

2. The apparatus of claim 1, wherein the equivalent source calculation unit comprises:

an analytical solution calculation unit to obtain an analytical solution vector from an analytical solution of a Laplace-domain wave equation in a homogeneous half space by a real source; and

a matrix-multiplying unit to obtain the vector of the equivalent source by multiplying the analytical solution vector by an impedance matrix of the Laplace-domain wave equation.

3. The apparatus of claim 1, wherein the equivalent source is located at one of points defining virtual grids on which the receivers are arranged.

4. The apparatus of claim 1, further comprising an image transformation unit to color image the subsurface structure using the modeling parameter data.

5. The apparatus of claim 1, wherein a plurality of equivalent sources are located at points defining virtual grids on which the receivers are arranged.

6. A method for imaging a subsurface structure, comprising:

obtaining an equivalent source that is equivalent to a real source, wherein the equivalent source is at least one virtual source located at one of points defining virtual grids in an area to be measured; and

obtaining modeling parameter data about the subsurface structure, by performing Laplace-domain waveform inversion on a plurality of seismic signals acquired by a plurality of receivers arranged on the virtual grids in the area to be measured, based on a vector of the equivalent source.

7. The method of claim 6, comprising:

obtaining an analytical solution vector by obtaining an analytical solution of a Laplace-domain wave equation in a homogeneous half space by a real source, on a virtual grid defined by arrangement of the receivers; and

obtaining the vector of the equivalent source by multiplying the analytical solution vector by an impedance matrix of the Laplace-domain wave equation.

8. The method of claim 6, further comprising color imaging the subsurface structure from the modeling parameter.

9. The method of claim 6, wherein the analytical solution vector is given by:

10. A recording medium storing a program by which the method of claim 6 is implemented.

11. A subsurface structure imaging apparatus for modeling a subsurface structure with respect to a grid having a size of 80 through 220 m, using data obtained by measuring a wavefield emitted from a source at a depth of 5 through 20 m from the surface of the water through a streamer.