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Evaluation of Hydrogeologic Seal Capacity of Mudstone in the Yeongil Group, Pohang Basin, Korea: Focusing on Mercury Intrusion Capillary Pressure Analysis
포항분지 영일층군 이암층의 수리지질학적 차폐능 평가: 수은 모세관 압입 시험의 결과 분석을 중심으로
Econ. Environ. Geol. 2020 Feb;53(1):23-32
Published online February 28, 2020;
Copyright © 2020 the Korean society of economic and environmental gelology.

Seon-Ok Kim1, Sookyun Wang1* and Minhee Lee2
김선옥1 · 왕수균1* · 이민희2

1Department of Energy Resources Engineering, Pukyong National University
2Department of Earth Environmental Sciences, Pukyong National University
1부경대학교 에너지자원공학과, 2부경대학교 지구환경과학과
Received January 29, 2020; Revised February 25, 2020; Accepted February 26, 2020.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Geological CO2 sequestration is a global warming response technology to limit atmospheric emissions by injecting CO2 captured on a large scale into deep geological formations. The presented results concern mineralogical and hydrogeological investigations (FE-SEM, XRD, XRF, and MICP) of mudstone samples from drilling cores of the Pohang basin, which is the research area for the first demonstration-scale CO2 storage project in Korea. They aim to identify the mineral properties of the mudstone constituting the caprock and to quantitatively evaluate the hydrogeologic sealing capacity that directly affects the stability and reliability of geological CO2 storage. Mineralogical analysis showed that the mudstone samples are mainly composed of quartz, K-feldspar, plagioclase and a small amount of pyrite, calcite, clay minerals, etc. Mercury intrusion capillary pressure analysis also showed that the samples generally had uniform particle configurations and pore distribution and there was no distinct correlation between the estimated porosity and air permeability. The allowable CO2 column heights based on the estimated pore-entry pressures and breakthrough pressures were found to be significantly higher than the thickness of the targeting CO2 injection layer. These results showed that the mudstone layers in the Yeongil group, Pohang basin, Korea have sufficient sealing capacity to suppress the leakage of CO2 injected during the demonstration-scale CO2 storage project. It should be noticed, however, that the applicability of results and analyses in this study is limited by the lack of available samples. For rigorous assessment of the sealing efficiency for geological CO2 storage operations, significant efforts on collection and multi-aspect evaluation for core samples over entire caprock formations should be accompanied.
Keywords : geological CO2 storage, mudstone, Pohang basin, seal capacity, mercury intrusion capillary pressure analysis


April 2020, 53 (2)