Simulation of Dynamic Triggering of Acoustic Emissions using a Bonded-Particle Method

• Author / Creator

  Lu,Hang

• Microseismic events are commonly recorded during hydraulic fracturing experiments. In microseismic interpretations, each event is often regarded as causally independent and uncorrelated to neighbouring ones. In reality, both the rock deformation (static stresses) and transient wave motion (dynamic stresses) associated with microseismic events influence the stress field together with the external loading (fluid injection). It is thus very likely that many microseismic events are caused by both static and dynamic stress changes. In other words, some events may be caused by propagation of transient waves instead of the stress changes purely related to fluid injection. In this thesis, dynamic triggering of acoustic emissions is studied as an analogy of microseismic events using Bonded Particle Method (BPM). A biaxial deformation test on a rock core sample is simulated. First, a major event is created and how dynamic waves influence the occurrence of the subsequent ones is qualitatively and quantitatively studied. Then an external vibration is applied to the model to investigate the influence of transient wave motion on failure in a controlled fashion. It is found that dynamic stresses can alter the stress field and hence cause a favorable change in the stress state for bond breakages. The external vibration can advance the formation of the upcoming large local failure events and delay or advance the final catastrophic failure depending on the vibrational amplitude.

• Subjects / Keywords

  • Acoustic emission
  • Dynamic triggering
  • Bonded-particle method

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R37D2QN04

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.