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2021 Vol.58, Issue 3

Research Paper

Geochemical Effect of Geothermal Water Flushing during Enhanced Geothermal Systems Operation

인공저류층 지열시스템 운영 중 지열수 플러싱 공정의 지화학적 영향

Junbeum Lee12
,
Eunhyea Chung34*
이 준범12
,
정 은혜34*
1Integrated PhD Program, Department of Energy Systems Engineering, Seoul National University, Seoul, Korea
2Researcher, Research Institute of Energy and Resources, Seoul National University, Seoul, Korea
3Associate Professor, Department of Energy Systems Engineering, Seoul National University, Seoul, Korea
4Adjunct Researcher, Research Institute of Energy and Resources, Seoul National University, Seoul, Korea
1서울대학교 에너지시스템공학부 석박사통합과정
2서울대학교 에너지자원신기술연구소 연구원
3서울대학교 에너지시스템공학부 부교수
4서울대학교 에너지자원신기술연구소 겸임연구원
*Corresponding Author
30 June 2021. pp. 205-214
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Abstract

Scale production occurs during enhanced geothermal system (EGS) processes due to various conditions. The production of scales in pipes or fractured reservoir narrows the diameter of the injection and production well, decreasing permeability and reducing EGS efficiency. However, geothermal water flushing during EGS processes can be implemented to recover the permeability. In this study, an experimental instrument to simulate a geothermal system was applied to observe the chemical composition change of core and water samples. To simulate the EGS, an experiment was conducted by injecting the geothermal fluid in several cycles to the fractured core. Results showed that Si ions decreased in the geothermal fluid and permeability decreased due to precipitation. Thereafter, flushing was applied, and dissolution occurred inside the fracture, increasing the permeability.

Keywords
Enhanced Geothermal Systems (EGS)
Geochemical reaction
Scale
Permeability
Flushing

인공저류층 지열시스템(EGS) 운영 중 생길 수 있는 대표적인 문제점은 스케일의 생성인데 여러 주변 환경 조건으로부터 영향을 받는다. 파이프 또는 저류층 내에서 생기는 스케일 물질로 인하여 주입정과 생산정의 직경이 좁아지거나 저류층의 투수성이 줄어들어 EGS의 효율성을 낮추게 된다. 낮아진 효율을 회복하기 위한 방법 중의 하나로 EGS 운영 중 지열수 플러싱이 적용될 수 있다. 본 연구에서는 EGS 모사 실험장치를 이용하여 수리자극 중 EGS 저류층 내 암석의 광물 조성 변화와 순환수의 화학조성 변화를 관찰하였다. EGS를 모사하기 위하여 지열수를 여러 번 순환하여 균열된 코어에 투과시키는 실험이 진행되었다. 실험결과에 의하면 지열수 내의 Si 이온이 감소하고 균열 내 형성되는 침전으로 투수율이 감소하였다. 이를 해결 하기 위하여 더 높은 압력으로 지표수를 사용하여 플러싱을 실험적으로 적용시킬 때 침전된 광물이 용해되는 결과를 확인하였다.

키워드
인공저류층 지열시스템
지화학반응
스케일
투수성
플러싱
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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 : 58
  • No :3
  • Pages :205-214
  • Received Date : 2021-05-27
  • Revised Date : 2021-06-22
  • Accepted Date : 2021-06-25
  • DOI :https://doi.org/10.32390/ksmer.2021.58.3.205
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