PML absorption boundary based three-dimensional sound wave numerical simulation method

Abstract

The invention discloses a PML absorption boundary based three-dimensional sound wave numerical simulation method. The method mainly comprises the following steps of S1, applying regular grids in an internal computation region, and defining wave field pressure only on regular grid integer nodes; applying staggered grids in a PML absorption region, defining wave field pressure on staggered grid integer nodes, and defining particle velocity components and medium density on staggered grid half nodes; S2, updating wave field pressure values through a second-order hyperbolic partial differential wave equation in the internal computation region; calculating particle velocity components and wave field pressure values through a first-order stress velocity-equation in the PML absorption region. By the aid of the method, the memory requiring amount is reduced, the simulative model scale is expanded, and the PML boundary processing is simple. The method is particularly applicable to seismic wave numerical simulation or reverse-time migration in the oil-gas exploration field.

Description

technical field [0001] The invention belongs to the field of oil and gas exploration, and relates to a three-dimensional acoustic wave numerical simulation method based on PML absorption boundaries. Background technique [0002] In the 3D acoustic wave simulation based on the PML absorption boundary, the calculation area is divided into two parts: one is the internal calculation area, and the other is the PML absorption area, such as figure 2 As shown in , the gray shaded part of the boundary represents the PML absorption area, and the internal blank is the internal calculation area. ① indicates the corner boundary of the PML absorption area, and ② indicates the edge boundary of the PML absorption area. [0003] Taking the model with N×N×N three-dimensional grid and PML boundary thickness as M grid points as an example, there are two simulation methods: [0004] Method 1: Use a regular grid, that is, all physical quantities and pressure values ​​are defined on the grid node...

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Problems solved by technology

[0009] It can be seen that the technical problem of the above method 1 is that too many auxiliary variables are introduced, and the PML boundary processing is more complicated;

[0010] Although the above method 2 is beneficial to the processing of the PML boundary, it needs to define the pressure value and particle velocity in the entire grid at the same time, and the memory usage increases significantly.

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