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Mechanical and Civil Engineering Seminar

Thursday, February 16, 2023
11:00am to 12:00pm
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Gates-Thomas 135
Bayesian Inference of Poroelastic Properties Using an Energy-based Poromechanics Model
Dr. Mina Karimi, Postdoctoral Scholar Research Associate, California Institute of Technology,

Mechanical and Civil Engineering Seminar Series

Title: Bayesian Inference of Poroelastic Properties Using an Energy-based Poromechanics Model

Abstract: Fluid injection into deep underground formations related to CO2 sequestration, wastewater injection, etc., is increasingly relevant for the energy sector. Injected fluids in porous deformable elastic media increase pore pressure, reduce normal effective stress, and change the available friction along fractures and faults. Consequently, slip can occur, causing seismic events. Understanding this mechanism and identifying the stress and pressure fields around the injection wellbores play a central role in assessing the seismic hazard. One of the crucial steps is inferring the unknown model parameters (i.e., poroelastic properties) from the noisy data of injection sites. Due to the indirect relation between the uncertain parameters and the empirical observation (i.e., number of earthquakes and stress drop variations in injection sites) and the high dimension of the parameters' domain, the inverse problem is computationally expensive. Here, we present a variational energy-based continuum mechanics framework to model large-deformation poroelasticity to characterize the evolution of stress, pore pressure, and other mechanical quantities. We also, adopt a Bayesian inference framework to integrate the partial differential equations (PDEs) of the forward mechanical model with models of uncertainty for observations and parameters. To quantify the uncertainty and predictability of the Bayesian method's solution, we investigate accelerated Markov Chain Monte Carlo (MCMC) sampling algorithms, and their challenges to explore high-dimension parameter spaces.

Bio: I am a postdoctoral scholar in the Mechanical and Civil Engineering Department at Caltech, working with Kaushik Bhattacharya. I received my Ph.D. degree from Carnegie Mellon University, where I was advised by Matteo Pozzi and Kaushik Dayal, and received the Dowd graduate fellowship from the college of engineering. My PhD research focused on large-scale inverse problems with application to geological problems. Before CMU, I graduated with Master's degree in Structural Engineering, and Bachelor's degree in Civil Engineering from Tehran University.

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.

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