Real-Time Joint Inversion of Borehole EM and Acoustic Data
The aim of this PhD project is to develop near real-time methods for the inversion of electromagnetic and acoustic data in logging-while-drilling (LWD) applications. The first phase of the project will focus on separate inversion of the two data types. Forward modelling for both electromagnetic and acoustic algorithms will be based on integral-equation methods, with the goal of developing efficient methods suitable for fast and accurate inversion in borehole scenarios.
Project description
For the electromagnetic problem, the project will investigate improved regularization strategies, including coupling between different components of the conductivity tensor. Similar ideas will be explored for acoustic inversion, for example through coupling between elastic parameters. Such regularization may help reduce the non-uniqueness of the inverse problem and improve the stability and accuracy of the recovered models. The project will also examine whether alternative background models in the Green’s tensor formulation can reduce the effective contrast and thereby improve computational efficiency.
In the second phase, the electromagnetic and acoustic inversion methods will be combined into a joint inversion framework for LWD. Regularization strategies developed for the separate inversions will be extended to couple information across the two data types. The project will also investigate petrophysical regularization based on rock-physics relations, with the aim of improving inference of reservoir parameters such as porosity and water or hydrocarbon saturation.