Geophysics and Geophysical Exploration ISSN:1229-1064(Print) 2384-051X(Online) 지구물리와 물리탐사

A magentotelluric (MT) survey at the Uiseong area has been performed for the site investigation of pilot scale CO2 sequestration. The purpose of the MT survey is to delineate deeply extended fracture systems that can act as a leakage path of injected CO2 plume. Since the target area is extremely noisy in electromagentic sense, low frequency data below 1 Hz cannot be used for inversion. Two- and three-dimensional interpretation of the MT data showed a very clear conductive anomaly, which has the direction of N55~65˚W and is extended roughly down to 1.6 km. It have the same direction with the strike-slip faults, the Gaeum and Geumcheon Faults. On the contrary, the eastern part of the survey area shows relatively homogeneous to the depth of 2 km though some small fractures at shallow depths can be found. Test drilling and high-definition borehole surveys should be followed at the eastern part of the survey area and hydraulic fracturing is required for injection of CO2, because mean porosity of the sedimetary rock in the area is only 1.47%.