Journal of the Korean Institute of Gas (한국가스학회지)

The Korean Institute of GAS (한국가스학회)
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Experimental Study on the Adsorption Characteristics of Methane Gas Considering Coalbed Depth in Coalbed Methane Reservoirs

석탄층 메탄가스 저류층에서 탄층 심도를 고려한 메탄가스의 흡착 특성에 관한 실험 연구

  • Chayoung Song (Department of Energy and Resources Engineering, Chonnam National University) ;
  • Dongjin Lee (E&P Overseas Business Department II, Korea National Oil Corporation) ;
  • Jeonghwan Lee (Department of Energy and Resources Engineering, Chonnam National University)
  • 송차영 (전남대학교 에너지자원공학과) ;
  • 이동진 (한국석유공사 해외사업2처) ;
  • 이정환 (전남대학교 에너지자원공학과)
  • Received : 2023.02.28
  • Accepted : 2023.04.25
  • Published : 2023.06.30
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Abstract

This study presents the experimental results to measure the adsorption amount of methane gas by coal according to the conditions of a coalbed methane (CBM) reservoir. Adsorbed gas to coal seam particles was measured under reservoir conditions (normal pressure ~ 1,200 psi pressure range, temperature range15 ~ 45℃) using coal samples obtained from random mines in Kalimantan Island, North Indonesia. The obtained amount of absolute adsorbed gas was applied to triangular with linear interpolation to calculate the maximum amount of adsorbed gas according to temperature and pressure change, at which no experiment was performed. As a result, it was revealed that the amount of adsorbed gas to coal particles increased as the pressure increased and temperature decreased, but the increase of the amount of adsorbed gas decreased at more than an appropriate depth(1,000 ft). In the cleat permeability and cleat porosity for each depth of the coal bed considering the effective stress, the cleat permeability was 28.86 ~ 46.81 md, and the cleat porosity was 0.83 ~ 0.98%. This means that the gas productivity varies significantly with the depth because the reduction of the permeability according to the depth in the coal seam is significant. Therefore, a coalbed depth should be considered essential when designing the spacing of production wells in a coalbed methane reservoir in further study.

본 연구에서는 석탄층 메탄가스(coalbed methane, CBM)의 저류층 조건에 따른 석탄의 메탄가스 흡착량 측정 실험을 수행하였다. 인도네시아 북부 칼리만탄 섬 내 임의의 광구에서 취득한 석탄시료를 사용하여 저류층 조건(상압 ~ 1,200 psi 압력범위, 15 ~ 45℃ 온도 범위)에서 탄층 입자에 대한 가스흡착량을 측정하였으며, 취득된 절대 흡착량에 삼각선형보간법을 적용하여 실험이 수행되지 않은 온도 및 압력 범위에서 최대 가스흡착량을 산출하였다. 실험 결과, 압력이 증가하고 온도가 감소할수록 석탄 입자에 대한 가스흡착량이 증가하지만 적정 심도(1,000 ft) 이상에서는 그 증가폭이 감소하는 것을 확인하였다. 유효응력을 고려하여 석탄층의 심도별 탄리 투과도와 탄리공극률을 산출한 결과, 탄리투과도는 28.86 ~ 46.81 md, 탄리공극률은 0.83 ~ 0.98%로 나타났다. 이는 석탄층에서 심도에 따른 투과도 감소폭이 크기 때문에 심도에 따른 가스 생산성이 크게 변함을 의미한다. 따라서 향후 석탄층 메탄가스 저류층에서 생산정 간격 설계 시 석탄층의 심도조건을 필수적으로 고려해야 한다.

Keywords

Acknowledgement

본 연구는 한국에너지기술평가원(KETEP)의 지원을 받아 수행한 연구 과제입니다(과제번호 20212010200010). 또한, 본 연구는 국토교통부/국토교통과학기술진흥원의 지원으로 수행되었습니다(과제번호 RS-2022-00143541).

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