Variational Bayesian experimental design for geophysical applications: seismic source location, amplitude versus offset inversion, and estimating CO2 saturations in a subsurface reservoir

TL;DR

This paper introduces variational Bayesian experimental design methods for geophysical applications, demonstrating their advantages in optimizing survey designs for source localization, seismic inversion, and CO2 saturation estimation, with significant computational savings.

Contribution

The paper presents novel variational design methods tailored for geophysics, enabling efficient and question-specific experiment optimization compared to traditional approaches.

Findings

Variational methods effectively optimize geophysical experiments.

Optimal designs vary significantly based on specific questions.

Substantial computational savings achieved with variational approaches.

Abstract

This paper introduces variational design methods that are novel to Geophysics, and discusses their benefits and limitations in the context of geophysical applications and more established design methods. Variational methods rely on functional approximations to probability distributions and model-data relationships. They can be used to design experiments that best resolve either all model parameters, or the answer to specific questions about the system to be interrogated. The methods are tested in three schematic geophysical applications: (i) estimating a source location given arrival times at sensor locations, and (ii) estimating the contrast in seismic wavefield velocity across a stratal interface given measurements of the amplitudes of seismic wavefield reflections from that interface, and (iii) designing a survey to best constrain CO2 saturation in a subsurface storage scenario. Variational methods allow the value of an experiment to be calculated and optimised simultaneously, which results in substantial savings in computational cost. In the context of designing a survey to best constrain CO2 in a subsurface storage scenario, we show that optimal designs may change substantially depending on the questions of interest. Overall, this work indicates that optimal design methods should be used more widely in Geophysics, as they are in other scientifically advanced fields.