Automated Anisotropic Velocity Model Calibration Using Gaussian Particle Swarm Optimisation
P. Usher, J. Huang and J. Montes
Event name: 81st EAGE Conference and Exhibition 2019
Session: Micro and Passive Seismic I
Publication date: 03 June 2019
Info: Extended abstract, PDF ( 506.44Kb )
Price: € 20
Velocity model calibration is an important part of microseismic processing. Microseismic data is important for monitoring the safety and effectiveness of hydraulic fracturing in hydrocarbon reservoirs. Here we use an automated calibration algorithm to update an isotropic sonic log velocity model based on the arrival time of calibration events affected by anisotropy. We increase the complexity of the model to consider VTI anisotropy from the shale formation. There are three parameterisations 1) isotropic 2) where the anisotropy is proportional to the inverse of the sonic log and 3) unconstrained anisotropy. The fully anisotropic model takes longer to run but reduces artefacts in the event depths. Model 2) performs better than model 1) and only has three extra parameters which have a limited effect on performance and so it can be applied in real-time operations. This work shows that taking anisotropy into account can remove event location artefacts. Our automated methodology allows for further developments in joint inversion of velocity and microseismic locations.