NUMERICAL SIMULATION OF MICROSEISMIC WAVEFIELDS WITH MOMENT-TENSOR SOURCES
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- 英文论文题名：NUMERICAL SIMULATION OF MICROSEISMIC WAVEFIELDS WITH MOMENT-TENSOR SOURCES
- 论文作者：Lei LI ; Hao CHEN ; Xiu-ming WANG
- 英文论文作者：Lei LI ; Hao CHEN ; Xiu-ming WANG ; Institute of Acoustics ; Chinese Academy of Sciences ; University of Chinese Academy of Sciences
- 年：2016
- 作者机构：Institute of Acoustics, Chinese Academy of Sciences;University of Chinese Academy of Sciences;
- 英文论文关键词：Microseismic monitoring ; FDM ; Moment-tensor ; Three-dimensional ; VTI
- 会议召开时间：2016-10-21
- 会议录名称：2016年全国压电和声波理论及器件应用研讨会论文摘要集
- 英文会议录名称：Abstract Book of 2016 Symposium on Piezoelectricity, Acoustic Waves and Device Applications
- 语种：英文
- 分类号：P631.4
- 学会代码：AGLU
- 会议名称：2016年全国压电和声波理论及器件应用研讨会
- 会议地点：中国陕西西安
- 主办单位：中国力学学会、中国声学学会、IEEE UFFC分会
- 学会名称：中国力学学会
- 页数：2
- 文件大小：11k
- 原文格式：D
- 会议级别：全国
摘要
Background, Motivation and Objective Microseismic monitoring technology has been widely used in many geophysical areas such as oil and gas reservoir monitoring, rock burst monitoring of mines and tunnels, geothermal exploration monitoring and natural microseismicity analysis of geological structure. The source mechanism of microseisms in hydraulic fracturing is the basis to further interpret the growth of fractures and can provide important parameters for discrete fracture network(DFN) modeling and stimulated reservoir volume(SRV) estimation. Forward numerical simulation of various types of microseismic sources can not only help to investigate the wavefield characteristics, but also lay the foundation for source location and source mechanism inversion. Statement of Contribution/Methods Microseismic monitoring is also called passive seismic monitoring, which is similar to earthquake monitoring and the impacts of focal mechanisms should be considered. Meanwhile, microseismic monitoring belongs to seismic exploration technologies and is relative small-scale, so numerical simulations methods, such as finite difference method(FDM) can be used to model microseismic wavefields and records. In this paper, equations of equivalent body forces with stress components and particle velocity components are concluded, and then they are included in the staggered-grid based FDM to represent moment-tensor source formulations. Microseismic wavefields based on three typical moment-tensor sources(include ISO, DC and CLVD source) are simulated and analyzed. Results Microseismic wavefields and records with different moment-tensor sources are simulated by staggered-grid based FDM in this paper. The feasibility and validity of the method are verified by comparing simulated results with far-field analytic solutions under the condition of three-dimensional isotropic homogeneous model. Results of isotropic and transverse isotropic with a vertical axis of symmetry(VTI) models show response characteristics of different microseismic sources, which can offer fundamental guidance and instruction for subsequent microseismic data processing(such as seismic phase identification) and interpretation. Through the forward modeling of microseismic wavefields with the surface star-array monitoring, the feasibility of source mechanism inversion by P-wave polarity for surface monitoring has been primarily demonstrated.Discussion and Conclusions In this paper, although only three typical moment-tensor sources are simulated and discussed, any type of moment-tensor sources can be decomposed into ISO, DC and CLVD components and implemented with equivalent body forces. Following conclusions can be drew from simulated results of different moment-tensor sources in different media:(a) In VTI model, not only P-wave but also S-wave can be excited by ISO source, and the velocity is dependent on propagation directions, which presents the characteristics of anisotropic media.(b) DC source can excite P-wave in both isotropic and anisotropic media, and CLVD source excites much stronger S-wave energy than that of P-wave.(c) When the surface monitoring aperture and azimuth coverage are enough, the P-wave polarity can be used in source mechanism inversion.
Background, Motivation and Objective Microseismic monitoring technology has been widely used in many geophysical areas such as oil and gas reservoir monitoring, rock burst monitoring of mines and tunnels, geothermal exploration monitoring and natural microseismicity analysis of geological structure. The source mechanism of microseisms in hydraulic fracturing is the basis to further interpret the growth of fractures and can provide important parameters for discrete fracture network(DFN) modeling and stimulated reservoir volume(SRV) estimation. Forward numerical simulation of various types of microseismic sources can not only help to investigate the wavefield characteristics, but also lay the foundation for source location and source mechanism inversion. Statement of Contribution/Methods Microseismic monitoring is also called passive seismic monitoring, which is similar to earthquake monitoring and the impacts of focal mechanisms should be considered. Meanwhile, microseismic monitoring belongs to seismic exploration technologies and is relative small-scale, so numerical simulations methods, such as finite difference method(FDM) can be used to model microseismic wavefields and records. In this paper, equations of equivalent body forces with stress components and particle velocity components are concluded, and then they are included in the staggered-grid based FDM to represent moment-tensor source formulations. Microseismic wavefields based on three typical moment-tensor sources(include ISO, DC and CLVD source) are simulated and analyzed. Results Microseismic wavefields and records with different moment-tensor sources are simulated by staggered-grid based FDM in this paper. The feasibility and validity of the method are verified by comparing simulated results with far-field analytic solutions under the condition of three-dimensional isotropic homogeneous model. Results of isotropic and transverse isotropic with a vertical axis of symmetry(VTI) models show response characteristics of different microseismic sources, which can offer fundamental guidance and instruction for subsequent microseismic data processing(such as seismic phase identification) and interpretation. Through the forward modeling of microseismic wavefields with the surface star-array monitoring, the feasibility of source mechanism inversion by P-wave polarity for surface monitoring has been primarily demonstrated.Discussion and Conclusions In this paper, although only three typical moment-tensor sources are simulated and discussed, any type of moment-tensor sources can be decomposed into ISO, DC and CLVD components and implemented with equivalent body forces. Following conclusions can be drew from simulated results of different moment-tensor sources in different media:(a) In VTI model, not only P-wave but also S-wave can be excited by ISO source, and the velocity is dependent on propagation directions, which presents the characteristics of anisotropic media.(b) DC source can excite P-wave in both isotropic and anisotropic media, and CLVD source excites much stronger S-wave energy than that of P-wave.(c) When the surface monitoring aperture and azimuth coverage are enough, the P-wave polarity can be used in source mechanism inversion.
Background, Motivation and Objective Microseismic monitoring technology has been widely used in many geophysical areas such as oil and gas reservoir monitoring, rock burst monitoring of mines and tunnels, geothermal exploration monitoring and natural microseismicity analysis of geological structure. The source mechanism of microseisms in hydraulic fracturing is the basis to further interpret the growth of fractures and can provide important parameters for discrete fracture network(DFN) modeling and stimulated reservoir volume(SRV) estimation. Forward numerical simulation of various types of microseismic sources can not only help to investigate the wavefield characteristics, but also lay the foundation for source location and source mechanism inversion. Statement of Contribution/Methods Microseismic monitoring is also called passive seismic monitoring, which is similar to earthquake monitoring and the impacts of focal mechanisms should be considered. Meanwhile, microseismic monitoring belongs to seismic exploration technologies and is relative small-scale, so numerical simulations methods, such as finite difference method(FDM) can be used to model microseismic wavefields and records. In this paper, equations of equivalent body forces with stress components and particle velocity components are concluded, and then they are included in the staggered-grid based FDM to represent moment-tensor source formulations. Microseismic wavefields based on three typical moment-tensor sources(include ISO, DC and CLVD source) are simulated and analyzed. Results Microseismic wavefields and records with different moment-tensor sources are simulated by staggered-grid based FDM in this paper. The feasibility and validity of the method are verified by comparing simulated results with far-field analytic solutions under the condition of three-dimensional isotropic homogeneous model. Results of isotropic and transverse isotropic with a vertical axis of symmetry(VTI) models show response characteristics of different microseismic sources, which can offer fundamental guidance and instruction for subsequent microseismic data processing(such as seismic phase identification) and interpretation. Through the forward modeling of microseismic wavefields with the surface star-array monitoring, the feasibility of source mechanism inversion by P-wave polarity for surface monitoring has been primarily demonstrated.Discussion and Conclusions In this paper, although only three typical moment-tensor sources are simulated and discussed, any type of moment-tensor sources can be decomposed into ISO, DC and CLVD components and implemented with equivalent body forces. Following conclusions can be drew from simulated results of different moment-tensor sources in different media:(a) In VTI model, not only P-wave but also S-wave can be excited by ISO source, and the velocity is dependent on propagation directions, which presents the characteristics of anisotropic media.(b) DC source can excite P-wave in both isotropic and anisotropic media, and CLVD source excites much stronger S-wave energy than that of P-wave.(c) When the surface monitoring aperture and azimuth coverage are enough, the P-wave polarity can be used in source mechanism inversion.
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