CO₂ Injection Monitoring Using Transient Electromagnetic in Ground-Borehole Configuration

Abstract

Using geophysical methods, specifically transient electromagnetic (TEM), for CO 2 monitoring is an effective way to detect CO 2 diffusion. In this work, a multi-scale finite-difference time-domain (FDTD) algorithm was established to monitor CO 2 by defining new iterative relations and approximating boundary conditions, which achieves unification in the time and space domain. The response curve characteristics of different forms of CO 2 were acquired by changing the receiver's depth and position, CO 2 resistivity, scale, and injection stage. Different models considering a planar, tilted, and large-scale CO 2 bodies, which were established to test the capacity of TEM monitoring for CO 2 . The TEM response of injected CO 2 bodies had obvious characteristics and the response curve had distinguishable differences from background. This phenomenon could provide reference models for real TEM CO 2 monitoring.