Adaptive Realization Method of Discontinuous Galerkin Finite Element Earthquake Numerical Simulation Algorithm
A technology of numerical simulation and implementation method, applied in seismology, seismic signal processing, geophysical measurement, etc., can solve problems such as global time step, and achieve the effects of novel theory, improved simulation calculation efficiency, and strong technical process practicability
Active Publication Date: 2020-09-15
CHINA PETROLEUM & CHEM CORP +1
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[0007] The present invention aims at the problem that the local small grid unit or malformed unit in the model will lead to a smaller global time step when using the discontinuous Galerkin finite element method (LF-DG) for numerical simulation of seismic wave propagation, by using the discontinuous Galerkin finite element method The local characteristics implement the p-adaptive algorithm, allowing each unit to set an independent spatial order, and then obtain an optimized local time step to improve the efficiency of simulation calculations
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[0076] figure 1 is the schematic diagram of the uniform model and the grid distribution;
[0077] The model is simulated using the P3 order algorithm. In order to meet the stability requirements of the global grid, the time step dt≤0.11ms, the simulation time step of 0.1ms is used. When dt=0.2ms time step is used for simulation, it can be seen from Fig. 2 that in order to meet the stability requirements, a small number of units in the local mesh refinement need to be calculated with p2-order units, and p3-order units are still used for simulation in other areas. Figure 2(b) shows the p-adaptive simulation results, and Figure 2(c) shows the difference between the p-adaptive simulation results and the single p3-order simulation results. Comparing the numerical magnitudes, the peak of the simulation results reaches 4*104, and the peak of the difference is 1000, that is, the difference is about 2-5%.
[0078] In Fig. 3, when dt=0.25ms is used, more units at the local mesh refin...
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Provided is a self-adaptive realization method of a discontinuous Galerkin finite element earthquake value simulation algorithm. The method includes the following steps: firstly, defining a mesh generation density and conducting non-structural mesh generation on a calculation area according to the mesh density; secondly, determining a polynomial expansion order p of each mesh unit; thirdly, decoupling two adjacent mesh units, and selecting an appropriate numerical flux format as a wave field exchanged mode of two adjacent mesh units; fourthly, performing numeralization on a decoupling equation, and obtaining a space discrete equation of each mesh unit; fifthly, solving an inner product among wave field functions on a common boundary of two adjacent units, and obtaining a boundary value mapping matrix; sixthly, selecting an appropriate time integral format; and seventhly, utilizing the boundary value mapping matrix to carry out mapping on adjacent unit wave fields different in order, calculating space discrete portions, applying hypocenter conditions, updating wave field components, and obtaining a simulation result.
Description
technical field [0001] The invention is a numerical simulation technology of seismic wave field applied to complex surface and complex structure, and specifically relates to a finite element numerical solution algorithm. Background technique [0002] At present, in the southern and western regions of my country, the focus of oil and gas seismic exploration is shifting to complex areas such as hills and piedmont structural belts. The surface conditions in these areas are extremely complex, with severe topographical ups and downs, great changes in elevation, and large changes in lithology velocity lead to serious inhomogeneity in the near-surface structure. At the same time, the underground structure is complex, such as strong folds, developed faults, steep structures, and large stratum changes. . They lead to problems such as low signal-to-noise ratio and difficult static correction of seismic data in these areas. Fundamentally solving these exploration problems requires an...
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IPC IPC(8): G01V1/36
CPCG01V1/362G01V2210/53
Inventor 薛昭佘德平杨丽
Owner CHINA PETROLEUM & CHEM CORP