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Research Paper (Special Issue)

Effects of Gravity on the Relative Permeability Curves of Supercritical CO2 and Brine: An Experimental Study Using Surrogate Fluids

초임계상 CO2와 염수의 상대투과도 곡선에 대한 중력의 영향: 대리유체를 사용한 실험적 연구

Changhun Lee1
,
Seung-Wook Ha2*
,
Kang-Kun Lee1
이 창훈1
,
하 승욱2*
,
이 강근1
1School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
2Research Institute of Basic Sciences, Seoul National University, Seoul, Korea
1서울대학교 지구환경과학부
2서울대학교 기초과학연구원
*Corresponding Author
28 February 2026. pp. 56-72
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Abstract

This study investigates the influence of gravity on relative permeability–saturation (kr–S) relationships. Steady-state relative permeability tests were conducted using a 1 m–long column designed by the authors and surrogate fluids. Both upward and downward flow conditions were tested across three intrinsic permeabilities and three total flow rates. The measured kr–S curves clearly exhibited directional dependence on gravity. Downward flow yielded a more stabilized flow front and more consistent non-wetting phase saturation, whereas upward flow promoted flow instability, resulting in greater spatial variability. Endpoint relative permeability (kr,end,NWP and kr,end,WP) results suggest that kr,end,NWP is governed mainly by connected flow pathways at steady state, whereas kr,end,WP can increase even at similar residual non-wetting phase saturation during imbibition because the spatial configuration of stranded non-wetting phase clusters constrains wetting-phase connectivity. These results highlight the importance of gravity-controlled directional dependency of the kr–S relationship and the need to incorporate this behavior into reservoir-scale models.

Keywords
CCS
gravity
directional kr–S relationship
surrogate fluid experiments

본 연구는 중력이 상대투과도–포화도 관계에 미치는 영향을 규명하고자 하였다. 이를 위해 길이 1 m의 컬럼을 제작하였으며, 대리유체를 이용하여 정상상태 상대투과도 실험을 수행하였다. 실험은 상향 및 하향 유동 조건에서 세 가지 고유투수계수와 세 가지 총 유량 조건에서 실시하였다. 측정된 상대투과도 곡선은 중력에 기인한 방향 의존성을 나타내었다. 하향 유동의 경우 유동 전면이 상대적으로 안정화되며 비습윤상 포화도가 비교적 균일하게 유지된 반면, 상향 유동에서는 유동 불안정성이 증대되어 포화도의 공간적 변동성이 증가하였다. 끝점 상대투과도(비습윤상/습윤상) 분석 결과, 비습윤상 끝점 상대투과도는 정상상태에서 형성되는 유동 경로의 연결성에 의해 주로 지배되는 것으로 확인되었다. 반면, 습윤상 끝점 상대투과도는 잔류 비습윤상 포화도가 유사한 조건에서도 흡수 과정에서 고립된 비습윤상 클러스터의 공간적 분포가 습윤상의 연결성을 제약함에 따라 증가할 수 있음을 확인하였다. 본 연구는 상대투과도 곡선이 중력의 영향으로 유동 방향에 따라 달리 나타남을 보여주며, 저류층 규모 모델에서 방향 의존성 고려의 필요성을 시사한다.

키워드
CO2 지중저장
중력
상대투과도 곡선의 방향성
대리유체 실험
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Information
  • Publisher :The Korean Society of Mineral and Energy Resources Engineers
  • Publisher(Ko) :한국자원공학회
  • Journal Title :Journal of the Korean Society of Mineral and Energy Resources Engineers
  • Journal Title(Ko) :한국자원공학회지
  • Volume : 63
  • No :1
  • Pages :56-72
  • Received Date : 2026-01-05
  • Revised Date : 2026-01-27
  • Accepted Date : 2026-01-28
  • DOI :https://doi.org/10.32390/ksmer.2026.63.1.056
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