News

Development of surface-wave monitoring system for leaked CO2using a continuous and controlled seismic source

Share :

■ Abstract

To detect CO2 leakage from CO2 geological storage, we describe a seismic monitoring method using a continuous and controlled seismic source system, the Accurately Controlled Routinely Operated Signal System (ACROSS). The method applies surface-wave analysis to monitor the shallow subsurface from the temporal-variation (time-variation) of surface-wave phase velocity. Our numerical simulation study for CO2 leakage through fault zones indicated that the spatial distribution of leaked CO2 can be estimated from small temporal-variation of local phase velocities (∼1–3%). To demonstrate the method in a field case, we analyzed continuous seismic records acquired with ACROSS. We clearly extracted a dispersion curve of surface waves in the frequency range excited by the ACROSS (5.015–15.015 Hz). In particular, we obtained reliable estimates of phase velocities in 10–15 Hz frequency range, in which the time-variation of phase velocities was better than 1% accuracy. This temporal stability was sufficient to allow us to detect changes in phase velocities associated with CO2 leakage before leaked CO2 reached the surface.

 

■ Publication

Title: Development of surface-wave monitoring system for leaked CO2 using a continuous and controlled seismic source

Authors: Tatsunori Ikeda, Takeshi Tsuji, Toshiki Watanabe, Koshun Yamaoka

Journal: International Journal of Greenhouse Gas Control

DOI: 10.1016/j.ijggc.2015.11.030