Abstract
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This paper presents an analytical approach to describe the flow of CO2 based on Buckley-Leverett (B-L) theory and dissolution of CO2 in a confined aquifer where CO2 is injected. By utilizing the analytical solution, it was conducted to analyze ultimate distribution of CO2 after the aquifer has been completely stabilized. From the results, it was confirmed that dissolution of CO2 in aquifer was considered to be an important factor to estimate the amount of upward movement of CO2 after the stabilization of the aquifer. In the analysis of formation characteristics, porosity is a parameter to determine a sequestration capacity of aquifer. As a result of analysis for porosity, when the same amount of CO2 was injected into aquifer, the radius of investigation by injection was the greater as the formation porosity was the lower due to its small volume of void space containing the fluid. Meanwhile, as another property of formation characteristics, permeability is a parameter to determine a feasible injection rate, because in the case of low permeable system a large pressure gradient can cause the fracture near injection well. Consequently, it is necessary to calculate the optimum injection rate corresponding to the permeability of aquifer. In the analysis of injection rate, it is possible to sequester a large amount of CO2 by the increasing operating pressure, however, in order to avoid formation damage near well due to the increased pressure at well it is necessary to determine optimum injection rate.
본 연구에서는 이산화탄소를 심부의 대수층에 주입했을 때, 대수층내에서 이산화탄소의 수평유동에 대한 간단한 Buckley-Leverett(B-L) 유동 이론해와 물에서 이산화탄소의 용해현상을 활용하여 대수층이 완전히 안정화된 이후에 대한 이산화탄소의 분포양상을 분석하였다. 분석결과, 이산화탄소의 용해도는 대수층이 안정화된 후 상부로 이동하는 이산화탄소의 양을 산출하는데 중요한 요인임을 확인하였다. 대수층의 특성에 대한 분석결과, 공극률은 이산화탄소의 격리량을 결정하는 요인으로서, 동일한 양의 이산화탄소를 대수층에 주입했을 경우 지층의 공극률이 작을수록 부존공간이 작으므로 이산화탄소의 주입 영향반경이 더 큰 것으로 나타났다. 한편, 대수층의 투과도는 이산화탄소의 주입량을 제한하는 중요한 특성으로서, 투과도가 낮을수록 주입정과 대수층사이의 압력구배가 커져서 주입정 부근에서 균열 생성의 위험이 커지므로 주입설계시 지층의 투과도 크기에 따라 적정한 주입량이 요구된다. 이산화탄소 주입량에 대한 분석에서는 주입량이 클수록 많은 양의 이산화탄소를 단기간에 주입할 수 있지만 주입정 부근에서 압력이 크게 증가되어 지층손상의 위험이 있으므로 지층압에 대한 정확한 예측을 통해 적정 주입량을 결정해야 함을 알 수 있었다.
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- Publisher :The Korean Society of Mineral and Energy Resources Engineers
- Publisher(Ko) :한국자원공학회
- Journal Title :Journal of the Korean Society for Geosystem Engineering
- Journal Title(Ko) :한국지구시스템공학회지
- Volume : 43
- No :4
- Pages :275-281
Journal of the Korean Society of Mineral and Energy Resources Engineers
