A time-field search method for AE source location with a regional velocity model
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RESEARCH ARTICLE - APPLIED GEOPHYSICS
A time‑field search method for AE source location with a regional velocity model Shunchuan Wu1,2 · Yixiong Gan1 · Jesse Hampton3 · Marte Gutierrez4 · Mingjing Lu5 · Xiaoqing Huang1 Received: 11 July 2019 / Accepted: 7 August 2020 © Institute of Geophysics, Polish Academy of Sciences & Polish Academy of Sciences 2020
Abstract A time-field search method was proposed for AE event source location, combining the grid search method and the database technique. Theoretical process was given, and laboratory hydraulic fracture stimulation experiments under true-triaxial confining stresses were performed to prove the practicability of the method. A regional velocity model with variable wave velocities and directionality was required to fit observations. The location results showed that time-field location method obtains the global optimal source location solution with a relatively high efficiency and accuracy. Keywords AE source location · Time-field method · Database · Hydraulic fracture · True-triaxial experiment
Introduction Acoustic emission (AE) is widely used to acquire the seismic data for crack monitoring and fracture characterization in geotechnical experiments (e.g., Wang and Ge 2008; Dong and Xi-Bing 2012; Pei et al. 2016). Though fractures can readily be characterized by AE event source location methods, improved algorithms are continuously being developed. * Yixiong Gan [email protected] Shunchuan Wu [email protected] Jesse Hampton [email protected] Marte Gutierrez [email protected] Mingjing Lu [email protected] 1
Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine, University of Science and Technology, Beijing 100083, China
2
Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China
3
University of Wisconsin-Madison, Madison, WI, USA
4
Colorado School of Mines, Golden, CO 80401, USA
5
School of Petroleum Engineering, China University of Petroleum (East China), Shandong, China
For instance, algorithms based on Gauss–Newton iterative method (such as the Geiger algorithm) are efficient in the source location process (e.g., Rabinowitz 1988), but occasionally there are convergence issues or issues with reliability (e.g., Thurber 1985). Several other location methods such as Simplex method (Prugger and Gendzwill 1998), which is shown to be more reliable, were proposed. However, both the algorithms based on Gauss–Newton iterative method and Simplex method have the defect that the result would converge to a local minimum rather than the global one, which usually leads to what is referred to as a local optimal solution (e.g., Jian et al. 2014). The advent of advanced computing techniques has allowed for Global Optimization methods to develop that combine several location algorithms (e.g., Chen et al. 2005). Differing from local optimization algorithms, which search for a minimum error near the initial value, Global Optimization methods search for a solu
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