Characteristics of South Korea's Geothermal Water in Relation to Its Geological and Geochemical Feature

Lee, Chung-Mo,Hamm, Se-Yeong,Lee, Cholwoo,Choi, Sung-Ja,Chung, Sang Yong Korean Society of Soil and Groundwater Environment 2014 지하수토양환경 Vol.19 No.2

The volcanic type of geothermal water is linked intimately to active or potentially active volcanoes and takes place near the plate boundaries. In contrast to the volcanic type, the geothermal water in Korea has a non-volcanic origin. Korea's geothermal water is classified into the residual magma (RM) type and deep groundwater (DG) type according to the criterion of $35^{\circ}C$. This study reviewed the relationship between the physical and chemical features of the 281 geothermal water sources in South Korea in terms of the specific capacity, water temperature, and chemical compositions of two different basements (igneous rock and metamorphic rock) as well as the geological structures. According to the spatial relationship between the geothermal holes and geological faults, the length of the major fault is considered a key parameter determining the movement to a deeper place and the temperature of geothermal water. A negligible relationship between the specific capacity (Q/s) and temperature was found for both the RM type and DG type with the greater specific capacities of the RM- and DG-igneous types than the RM- and DG-metamorphic types. No relationship was observed between Q/s and the chemical constituents ($K^+$, $Na^+$, $Ca^{2+}$, $Mg^{2+}$, $Zn^{2+}$, $Cl^-$, $SO_4{^{2-}}$, $HCO_3{^-}$, and $SiO_2$) in the DG-igneous and DG-metamorphic types. Furthermore, weak relationship between temperature and chemical constituents was found for both the RM type and DG type.

한국의 심부시추공 열적특성 평가

이철우(Cholwoo Lee),이영민(Youngmin Lee),박찬희(Chan-Hee Park),심병완(Byoung-Ohan Shim),김성균(Seong-Kyun Kim) 대한지질학회 2015 대한지질학회 학술대회 Vol.2015 No.10

Temperature and Compositional Characteristics of the Hot Spring Water in Korea

이철우(Lee, Cholwoo) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

We analyzed the temperature and chemical composition of 376 hot springs in Korea. It took about three days for the temperature to stabilize after the pumping test. After the stabilization, in-situ and laboratory analyses of the hot spring water were carried out. The average temperature and TDS were 29.95?C and 2,071mg/L, respectively. The temperature ranging 25-30?C were recorded from 70% of hot springs, and 30-35?C of 15.4%. The maximum temperature was about 78?C. The value of TDS in 79% of the wells was below 1,000 mg/L. 5.5% of the wells, mostly developed near seashore, shows higher values than 10,000mg/L of TDS suggesting the influence of seawater. The hot spring water shows 8.49 of pH representing a weak alkali. For the mineral compositions dissolved in the hot spring in Korea, Na (431 mg/L) and Ca (188 mg/L) are the major cations, and Cl (840 mg/L) and SO₄ (213 mg/L) are the major anions.

지온경사와 양수시험 자료를 활용한 심부 암반대수층 투수성 암반균열의 수리특성 연구

이항복(Hangbok Lee),이철우(Cholwoo Lee),박의섭(Eui-Seob Park) 한국암반공학회 2024 터널과지하공간 Vol.34 No.4

지하 심부를 대상으로 하는 에너지 저장 및 개발, 방사성폐기물 처분 등 여러 지하연구사업들에서 심부 암반대수층 내 지하수 흐름의 주요 통로가 되는 투수성 암반균열의 특성 정보들은 연구시설의 설계와 설 그리고 운영에 있어 중요한 평가 요소로 고려된다. 국내에는 심도가 매우 깊은 암반시추공에서 투수성 암반균열의 위치와 수리특성, 균열 사이에 발생할 수 있는 지하수 유동 양상에 관한 연구와 데이터베이스가 매우 부족한 실정이다. 본 논문에서는 지온경사와 양수시험 자료분석을 통해 심부 암반대수층 내 투수성 암반균열의 수리특성을 평가하였다. 먼저 온도검층을 통해 심부 지온 분포를 확인하고, 심도별 온도자료를 이용하여 선형회귀분석을 통해 지온경사를 도출하였다. 또한 양수시험을 통한 용출온도를 이용해, 균열암반에 대한 수리특성을 분석하였다. 최종적으로 이러한 물리검층과 수리시험 자료를 통합 분석함으로써 투수성 암반균열의 잠재적 위치와 수리특성, 그리고 시추공 내 지하수 흐름을 평가하였다. 본 연구에서 제안된 심부 투수성 암반균열의 특성평가 과정과 결과들은 심부 암반대수층을 대상으로 하는 지하연구사업들의 성공적인 수행을 위한 기초 자료로 활용될 것으로 기대된다. In various underground research projects such as energy storage and development and radioactive waste disposal targeting deep underground, the characteristics of permeable rock fractures that serve as major pathway of groundwater flow in deep rock aquifer are considered as an important evaluation factor in the design, construction, and operation of research facilities. In Korea, there is little research and database on the location and hydraulic characteristics of permeable rock fractures and the pattern of groundwater flow patterns that may occur between fractures in deep rock boreholes. In this paper, the hydraulic characteristics of permeable rock fractures in deep rock aquifer were evaluated through the analysis of geothermal gradient and pumping test data. First, the deep geothermal distribution was identified through temperature logging, and the geothermal gradient was obtained through linear regression analysis using temperature data by depth. In addition, the hydraulic characteristics of the fractured rock were analyzed using outflow temperature obtained from pumping tests. Ultimately, the potential location and hydraulic characteristics of permeable rock fractures, as well as groundwater flow within the boreholes, were evaluated by integrating and analyzing the geophysical logging and hydraulic testing data. The process and results of the evaluation of deep permeable rock fractures proposed in this study are expected to serve as foundational data for the successful implementation of underground research projects targeting deep rock aquifers.

동래온천의 장기적인 수질 변동 특성

전항탁 ( Hang-tak Jeon ),함세영 ( Se-yeong Hamm ),이철우 ( Cholwoo Lee ),이종태 ( Jong-tae Lee ),이정락 ( Jeong Rak Lee ) 대한지질공학회 2020 지질공학 Vol.30 No.3

본 연구에서는 1922년부터 2019년까지 동래온천수의 장기적인 온천수 수질 변화 특성을 살펴보았다. Mann-Kendall 분석과 Sen의 기울기에 의해서 동래온천수의 장기적인 수질 특성 변화를 분석하면, 온도, Ca, SiO₂, HCO₃는 증가 추세를 보이는 반면에 EC, Na, K, Mg, Cl, SO₄은 감소 추세를 보이거나 또는 거의 추세 변화를 보이지 않는다. 동래온천수의 수질유형은 시간경과에도 변하지 않고 Na-Cl형에 안정적으로 속하고 있다. 2004년, 2009년, 2014년, 2019년의 수질 자료를 이용한 공간 분포도에 의하면, 시기별로 변동을 보이며, 시료 채취 지점에 따라 값의 변화를 보인다. 이는 장기적인 온천수 개발에도 불구하고 동래온천수의 공간적인 수질 특성은 거의 일정하다는 것을 지시한다. In this study, Long-term change of water quality in Donrae Hot Spring was characterized using water quality data from 1922 to 2019. According to Mann-Kendall analysis and Sen's slope using long-term water quality data of Dongnae Hot Spring from 1922 to 2019, temperature, Ca, SiO₂, and HCO₃ show an increasing trend whereas EC, Na, K, Mg, Cl, and SO₄ show a decreasing trend or negligible trend. In addition, the water type of Dongnae Hot Spring stably belongs to Na-Cl type over time. The spatial distributions of water temperature and chemical constituents in 2004, 2009, 2014, and 2019 show variable patterns with showing some difference depending on sampling locations in different years. These results indicate that despite the long-term pumping of the hot spring water, the water quality is quite stable during the entire study period.

GFRP rebar를 적용한 하천수리제품의 성능평가

김용재(Kim, Yongjae),이규석(Lee, Kyusuk),박제영(Park, Jeyoung),조청휘(Cho, Chunghe),박철우(Park, Cholwoo),심종성(Sim, Jongsung) 한국콘크리트학회 2011 한국콘크리트학회 학술대회 논문집 Vol.2011 No.11

Applicability of thermal response tests for assessing in-situ CO₂ storage in a saline aquifer

Park, Chan-Hee,Lee, Seong Kon,Lee, Cholwoo,Kim, Seong-Kyun Elsevier 2018 ENERGY Vol.154 No.-

<P><B>Abstract</B></P> <P>The study aims to evaluate the method of Thermal Response Tests (TRTs) in assessing in-situ residual saturation of CO<SUB>2</SUB> storage in saline aquifers. Similar to TRTs, mathematically the same type of an exact analytical solution presented by Theis is well-established for the transient drawdown in an infinite uniform confined aquifer. With the change of supercritical CO<SUB>2</SUB> and saline water in pore space, the inverse models of temperature change over time either heating or cooling may lead to the detection of a change in thermal properties of fluids and sold matrix. In assessing the overall thermal conductivity using the three inverse models, the Wang model describes the saline aquifer of the interest structurally well among the chosen four conductivity models. The results of the Wang model and the arithmetic model showed almost insensitivity to the residual CO<SUB>2</SUB> saturation up to 50 percents in the estimation of the overall thermal conductivity, while they did a sensitivity to porosity variation of the same range. Accuracy analysis of the three inversion models showed that a developed nonlinear least square inverse model produces the least error in the estimation consistently with the wide range of the residual saturation variation of CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Applicability of TRTs is studied to assess in-situ CO<SUB>2</SUB> storage in a saline aquifer. </LI> <LI> Three inverse models are evaluated to assess the overall thermal conductivity. </LI> <LI> The nonlinear least square inverse model produces the least error in the assessment. </LI> </UL> </P>

Suitability Assessment of Reinforced Precast Concrete Blocks Incorporating Recycled Aggregate

Hanif, Asad(아사드 하니프),Kim, Yongjae(김용재),Lee, Hyeongi(이현기),Kim, Jieun(김지은),Park, Cholwoo(박철우),Sim, Jongsung(심종성) 한국콘크리트학회 2011 한국콘크리트학회 학술대회 논문집 Vol.2011 No.11

Deep Geothermal-water Characteristics of Tertiary Pohang in South Korea

( Woori Lim ),( Se-yeong Hamm ),( Cholwoo Lee ),( Seho Hwang ),( In-hwa Park ),( Yoon-ho Song ),( Hyeong-chan Kim ),( Chung-ryul Ryoo ),( Sul-min Yun ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Pohang area displays a larger potential of geothermal energy with the highest heat flow of ~83 mWm^-2 in South Korea. This study aims to reveal geothermal characteristics of four wells(BH-1 to BH-4 wells) of ~2,000 m in depth in Pohang area, using geophysical logs. The geology of the study area is composed of tertiary mudstone of 200 - 359.1 m, tuff of 73 - 240 m, sandstone/mudstone of 46 - 907 m, rhyolite of 259 - 375 m, and andesitic volcanic breccia of 8 34 m in thicknesses from the surface, with granodiorite at bottom. By the result, temperature and maximum electrical conductivity are 69.5°C at 1,502.6 m and 1,162 μS/cm at BH-2, 44.4°C at 912.3 m and 1,105 μS/cm at BH-3, and 82.5°C at 1,981.3 m and 3,412 μS/cm at BH-4. Thermal conductivity values at saturated state are 2.14 - 3.95 W/m-K at BH-1 and 2.36 - 3.61 W/m-K at BH-4. ß (determining heat flow rate and up/down direction) values were estimated by using 1-D steady-state heat transfer equation and were determined as -0.77 - 0.99 with the geothermal gradients (Ks) of 42.5 - 46.3°C/km at BH-1, -3.15 - 3.05 with the Ks of 25.0 - 29.1°C/km at BH-2, -1.80 - 2.09 with the Ks of 20.0 - 23.0°C/km at BH-3, and -4.10 - 5.18 with the Ks of 30.2 - 39.0°C/km at BH-4. Most depths of all the wells showed upward heat transfer. Based on the geophysical logs, the main aquifer is located between 200 and 300 meters.

온양지역 온천수의 수리화학적 특성

윤욱 ( Uk Yun ),조병욱 ( Byong Wook Cho ),이철우 ( Cholwoo Lee ) 대한지질공학회 2016 지질공학 Vol.26 No.4

온양지역 온천수의 수질특성을 파악하기 위하여 2011년과 2016년에 24개 온천수의 수질을 분석한 결과 5년 동안 수온과 수질에는 큰 변화가 없었다. 2016년 온천수의 수온과 SiO₂, F와는 정의 상관관계(r²=0.60, 0.47)를, Ca, Mg, Cl, SO₄, HCO₃, EC와는 부의 상관관계(r²=0.50, 0.11, 0.50, 0.63, 0.23, 0.51)를 나타낸다. 온천수의 수온과 pH는 양의 상관관계, DO와는 음의 상관관계를 보여 온양지역 온천수는 심부 기원임을 지시한다. 온천수 수질 유형은 대부분이 심부기원인 Na-HCO₃ 형으로 분류되나 일부 온천공은 Na(Ca)-HCO₃ 형으로도 분류되어 천부 지하수의 유입특성도 보인다. For the investigation of hydrochemical changes in hot spring waters from the Onyang hot spring area, we analyzed water chemistry of 24 hot spring waters in 2011 and 2016. The results showed that there is no significant change in temperature and properties of the hot spring waters. The relationship of 2016 between temperature and SiO₂ and F reveals a positive trend (r²=0.60, 0.47), and the relationship between temperature and Ca, Mg, Cl, SO₄, HCO₃, EC reveals a negative trend (r²=0.50, 0.11, 0.50, 0.63, 0.23, 0.51). The relationship between temperature and pH is a positive trend, while the one between temperature and DO is a negative trend, indicating that the source is from deep groundwater. When plotted on Piper diagram, most of which are Na- HCO₃ but several hot waters are classified as the Na(Ca)-HCO₃, indicating inflow of shallow groundwater was occurred.