Simulation on the cyclic operation of an open borehole thermal energy storage system under regional groundwater flow

이근상 한국지질과학협의회 2010 Geosciences Journal Vol.14 No.2

Coupled hydrogeological-thermal simulation is performed to analyze the effect of the configuration of boreholes and operation schedule on the performance of the borehole thermal energy storage (BTES) system. This paper presents numerical investigations and thermohydraulic evaluation on the cyclic flow regime operation of open borehole thermal energy storage system under the effects of regional groundwater flow. A three-dimensional numerical model for groundwater flow and heat transport in the ground is used to determine the annual variation of recovery temperature from the thermal energy storage. The model includes the effects of convective and conductive heat transfer, heat loss to the adjacent confining strata, and hydraulic anisotropy. The operation scenario consists of cyclic injection and recovery after holding interval and four periods per year to simulate the seasonal temperature conditions. For different parameters of the system, performances were compared in terms of the variation of extraction temperature. The calculated water temperature at the producing pipe remains relatively constant within a certain range throughout the simulation period. Heat loss, injection/production rate, aquifer thickness, and permeability ratio used in the model are shown to impact the predicted temperature profiles at each stage and the recovery water temperature. The influence of pressure gradient, which determines the direction and velocity of regional groundwater flow, is substantial for all cases considered.

지하수류가 대수층 열저장 시스템의 성능에 미치는 영향(3)

한정상,이주현,김영식,이광진,홍경식,Hahn, Jeongsang,Lee, Juhyun,Kiem, Youngseek,Lee, Kwangjin,Hong, Kyungsik 한국지하수토양환경학회 2017 지하수토양환경 Vol.22 No.4

When a warm well located downgradient is captured by cold thermal plume originated from an upgradient cold well, the warm thermal plume is pushed further downgradient in the direction of groundwater flow. If groundwater flow direction is parallel to an aquifer thermal energy storage (ATES), the warm well can no longer be utilized as a heat source during the winter season because of the reduced heat capacity of the warm groundwater. It has been found that when the specific discharge is increased by $1{\times}10^{-7}m/s$ in this situation, the performance of ATES is decreased by approximately 2.9% in the warm thermal plume, and approximately 6.5% in the cold thermal plume. An increase of the specific discharge in a permeable hydrogeothermal system with a relatively large hydraulic gradient creates serious thermal interferences between warm and cold thermal plumes. Therefore, an area comprising a permeable aquifer system with large hydraulic gradient should not be used for ATES site. In case of ATES located perpendicular to groundwater flow, when the specific discharge is increased by $1{\times}10^{-7}m/s$ in the warm thermal plume, the performance of ATES is decreased by about 2.5%. This is 13.8% less reduced performance than the parallel case, indicating that an increase of groundwater flow tends to decrease the thermal interference between cold and warm wells. The system performance of ATES that is perpendicular to groundwater flow is much better than that of parallel ATES.

상류 수위를 활용한 낙동강 하구둑 유출량 추정

심규현,정한철,황도현,김대선 한국수자원학회 2023 한국수자원학회논문집 Vol.56 No.3

The Nakdong Estuary Barrage is a tidal river environment where freshwater and seawater meet. This requires systematic monitoring of both surface water discharged from the estuary barrage and submarine groundwater discharge. In this study, upstream hydrograph and water balance analysis were used to calculate the change in water storage and discharge of the Nakdong Estuary Barrage. Submarine groundwater discharge was also calculated based on remote sensing-based digital elevation model data and hydrological modeling data, and compared with the estimated surface water discharge for analysis. Our proposed method can be efficiently applied to water resource management by utilizing remote sensing-based altimeter data other than field measurement. Because submarine groundwater discharge plays a significant role on the coastal environment as well as surface water discharge from an estuary barrage, studies on groundwater- surface water interactions in a river estuary should be sufficiently considered in monitoring the ecosystem of the Nakdong Estuary Barrage. 낙동강 하구둑은 담수와 해수가 만나는 감조하천 환경으로 하구둑에서 방류하는 지표수 유출량과 연안 해저 지하수 유출량에 대한 모니터링이 체계적으로 요구된다. 본 연구에서는 낙동강 하구둑 상류 지역에 위치한 수위자료와 물수지분석을 통하여 변화 저수량과 방류량을 계산하였다. 해저를 통한 육상에서의 지하수 유출도 원격탐사 기반 지형자료와 수문 모델링 자료를 근거로 산출하여 낙동강 하구둑 유출량과 비교 분석하였다. 제안된 방법은 현장 측정 이외의 원격탐사 기반 고도계 자료를 활용하여 수자원 관리에 효율적으로 적용할 수 있을 것으로 판단된다. 담수 지표수 유출량뿐만 아니라 해저 지하수 유출이 연안에 미치는 영향이 크기 때문에, 낙동강 하구둑 생태계 모니터링에서 담수와 해수의 상호 관계에 대한 연구도 충분히 고려되어야 할 것으로 사료된다.

CCS 지중저장에 대한 지진 위험의 법률적 대처방안

유태신,고문현 숭실대학교 법학연구소 2019 法學論叢 Vol.44 No.-

This study aims to study laws and institutions concerning risks and safety, etc. from the ground on land or earthquakes on storing carbon dioxide in the underground rock layer air gap under the sea surface, which is the main cause of greenhouse gas pollution. Currently, there are about 20 CCS facilities worldwide, including seven large capacity facilities and 13 medium-sized ones. Despite the high investment and management costs, CCS operation is operated because it is the only technology recognized by the UNFCCC that collects and stores CO2 based on fossil energy directly. And because it is an essential technology to cope with climate change. However, discussions are under way on the potential risks of storing carbon dioxide in the ground. Some of the dangers that could arise from leaking carbon dioxide stored underground to the surface include damage to humans and plants, drinking water pollution about groundwater contamination, and the risk of seismic activity caused by large-capacity carbon dioxide underground storage. To address this anxiety, it is necessary to widely introduce and share information about the storage of CCS to address misunderstanding and anxiety. Therefore, it is deemed necessary to supplement not only the storage company but also the national management system and legal responsibility for protecting the victims so that captured and transported carbon dioxide can be safely underground in the underground rock layer. To this end, the U.S., which records its long history and experience, seeks to address public anxiety through legal supplementation of CCS, which is essential to reducing greenhouse gas emissions, by looking at the legal system of CCS facilities in Germany, which provides a legal basis in response to various risk variables. 본 연구는 온실가스 오염의 주된 원인물질인 이산화탄소를 포집, 운송하여 육지의 지중이나, 해양 수면 아래의 지중 혹은 암석층 공극에 저장하는 것에 대하여 지진 등으로부터 위험과 안전성 등에 관한 법률·제도 등을 연구한 것이다. 현재 전 세계적으로 실증 및 상업용으로 200여개가 운영 중에 있으며 많은 투자비용이 소요됨에도 불구하고 CCS를 운영하는 이유는 화석에너지를 기반으로 하는 CO2를 직접 포집하여 저장하는 기술이자, UNFCCC로부터 인정받은 유일한 기술이기 때문이다. 그리고 CO2를 직접 포집하여 저장할 수 있는 가장 집적적인 온실가스 저감 기술이다. 최근 이산화탄소를 지중에 저장함으로써 발생하는 잠재적 위험(Risiko)의 논의가 한창이다. 지하에 저장된 이산화탄소가 지표에 누출됨으로써 생길 수 있는 위험으로는 인간 및 식물에 대한 피해, 지하수오염으로 인한 식수 오염, 대용량의 이산화탄소 지중저장으로 저장소 지표면 스트레스 유발로 인한 지진활동 촉발위험 등이 거론되고 있다. 이러한 불안을 해소하기 위해서는 CCS의 지중 저장에 대한 정보를 국민과 함께 소통하고 공유하여 오해와 불안을 모색할 필요가 있다. 따라서 이산화탄소를 지중에 안전하게 저장할 수 있도록 저장업체는 물론, 국가적 차원의 관리체계와 피해자 보호를 위한 법률적 책임이 보완되어야 할 것으로 간주된다. 이를 위해 우리나라의 CCS 운영 현황을 살펴보고, CCS 운영에 대한 오랜 역사와 경험을 보유하고 있는 미국, 다양한 위험변수에 대응하여 확고한 법률적 기반을 이루고 있는 독일의 CCS 법률적 제도 등을 연구하여, 확실한 지진 위험의 증거와 견해를 명쾌하게 제시하여 온실가스 감축에 필수적인 CCS에 관한 법률적 보완은 물론, 국민의 불안을 해소하고자 한다.

울산광역시 언양지역의 지하수 저류 변화량 산정 및 지질과의 관련성

김남훈 ( Nam Hoon Kim ),함세영 ( Se Yeong Hamm ),김태용 ( Tae Yong Kim ),정재열 ( Jae Yeol Cheong ),안정훈 ( Jeong Hoon An ),전항탁 ( Hang Tak Jeon ),김형수 ( Hyoung Soo Kim ) 대한지질공학회 2008 지질공학 Vol.18 No.3

지하수 저류 변화량 산정은 수리지질의 다양한 분야에서 활용되고 있으며, 갈수록 정확한 지하수 저류 변화량 산정이 요구되고 있다. 본 연구에서는 물수지분석법과 수리지질분석을 이용하여 울산광역시 언양지역의 지하수 저류 변화량을 산정하였다. 산정된 지하수 저류 변화량은 연평균 240 mm(연평균 강수량의 18.7%)이다. SCS-CN법으로 산정한 직접유출량은 연평균 강수량의 10.6%인 137 mm이다. Thornthwaite방법으로 산정한 증발산량은 연평균 강수량의 60.5%인 776 mm이다. 토양의 수리적 특성과 암석의 수리전도도 사이에는 연관성이 나타나지 않는다. 이는 지표부근의 토양의 수리적 특성과 천부의 지하 지층의 수리적 특성이 서로 다름을 지시하는 것이다. 지하수 저류 변화량과 수리특성인자들 간의 중다선형 회귀분석 결과, 강수량과 증발산량에 의해서 지하수 저류 변화량이 설명되는 중다선형 회귀식이 도출되었다. In diverse hydrogeologic fields, estimation of groundwater storage change is one of the most critical issues. Accurate estimation methods for determining groundwater storage change are required more and more. For Yeonyang area of Ulsan Megacity, groundwater storage change was estimated by using water balance method and hydrogeological analyses. The estimates of groundwater storage change was 240mm corresponding to 18.7% of mean annual precipitation. Direct runoff was calculated as 137 mm (10.6% of mean annual precipitation) by using SCS-CN method. Evapotranspiration based on the Thornthwaite method was calculated as 776 mm (60.5% of mean annual precipitation). Hydraulic properties of the soil types do not show any distinct relation with hydraulic conductivity of the rocks. This fact suggests that hydraulic property on the surface is different from that of subsurface geology. According to multi-linear regression analysis between groundwater storage change and hydraulic parameters, a regression equation of groundwater storage change, which was explained by precipitation and evapotranspiration, was established.

원격탐사의 지하수 수자원 적용 사례 고찰

이정호,Lee, Jeongho 대한원격탐사학회 2017 大韓遠隔探査學會誌 Vol.33 No.5

본 논문에서는 지하수 수자원의 부존 및 대수층의 역학적 변화를 원격 탐사 방법으로 해석한 연구사례를 고찰하였다. 지질 분포, 지표수 및 지형 고도차, 식생 분포, 강수량과 증발산량의 변화를 측정하는 기법에는 항공 자력 탐사 분석에 의한 지질 선구조 해석, DEM, 엽면적지수, 정규 식생 지수 및 지표면 에너지 밸런스 계산 등이 있으며, 모두 원격 탐사로 수득된 자료에 기반하며, 광역적 차원에서의 지하수 수자원 부존 여부를 정성적으로 분석할 수 있다. 위성 센서 자료의 직접 이용을 통한 지하수 부존 및 동력학의 정량적 해석은 현재까지 GRACE와 InSAR가 가장 각광받는 탐사 방법임을 알 수 있었다. GRACE는 미소 중력장 변화를 지구 표면 및 내부 수체의 질량 변화로 전환할 수 있는 센서 보유 위성으로서, 센서 자료의 보정이 필요 없고, 지하수 부존 정량 분석을 위한 보조 자료를 모두 다른 위성 센서 자료에서 수득할 수 있으며, 자료처리 알고리즘의 지속적인 개선이 진행되고 있어서, 전세계적으로 수많은 연구가 수행되었다. 그러나, 위성센서의 검출 한계로 인해 협소한 지역에서의 지하수 질량 변화 정량이 부정확할 수 있고, 현장 조사 자료와 연동할 경우 과대 추정된 결과가 도출될 수 있다. InSAR는 특정 대수층에서 지표의 수직 변위가 지하수위와 비례한다는 원리를 이용, mm 단위의 지표 수직 변위를 측정하여 대수층 및 대수층 내 지하수의 물리적 특징을 정량화할 수 있다. 그러나, 지표의 토지 피복이 단순한 건조-반건조 기후 지역에 한정되어 적용되고 있으며, 지표면과의 긴밀도 값 손실이 우려되는 지역에서는 적용이 힘들다. 상기 두 위성을 이용하여 우리나라 지하수 수자원의 질량 변화 및 흐름 특징을 광역적으로 정량화하기 위해서는 우리나라의 지형 및 지질, 자연 조건에 알맞은 자료 전처리 알고리즘 개발 및 적용이 선행되어야 할 것이다. Several research cases using remote sensing methods to analyze changes of storage and dynamics of groundwater aquifer were reviewed in this paper. The status of groundwater storage, in an area with regional scale, could be qualitatively inferred from geological feature, surface water altimetry and topography, distribution of vegetation, and difference between precipitation and evapotranspiration. These qualitative indicators could be measured by geological lineament analysis, airborne magnetic survey, DEM analysis, LAI and NDVI calculation, and surface energy balance modeling. It is certain that GRACE and InSAR have received remarkable attentions as direct utilization from satellite data for quantification of groundwater storage and dynamics. GRACE, composed of twin satellites having acceleration sensors, could detect global or regional microgravity changes and transform them into mass changes of water on surface and inside of the Earth. Numerous studies in terms of groundwater storage using GRACE sensor data were performed with several merits such that (1) there is no requirement of sensor data, (2) auxiliary data for quantification of groundwater can be entirely obtained from another satellite sensors, and (3) algorithms for processing measured data have continuously progressed from designated data management center. The limitations of GRACE for groundwater storage measurement could be defined as follows: (1) In an area with small scale, mass change quantification of groundwater might be inaccurate due to detection limit of the acceleration sensor, and (2) the results would be overestimated in case of combination between sensor and field survey data. InSAR can quantify the dynamic characteristics of aquifer by measuring vertical micro displacement, using linear proportional relation between groundwater head and vertical surface movement. However, InSAR data might now constrain their application to arid or semi-arid area whose land cover appear to be simple, and are hard to apply to the area with the anticipation of loss of coherence with surface. Development of GRACE and InSAR sensor data preprocessing algorithms optimized to topography, geology, and natural conditions of Korea should be prioritized to regionally quantify the mass change and dynamics of the groundwater resources of Korea.

수리영역 개념을 적용한 단열암반의 지하수유동체계 해석

조성일 ( Sung Il Cho ),김천수 ( Chun Soo Kim ),배대석 ( Dae Seok Bae ),김경수 ( Kyung Su Kim ),송무영 ( Moo Young Song ) 대한지질공학회 2006 지질공학 Vol.16 No.1

본 연구는 지하유류저장공동 굴착 시 조사된 단열체계 및 수리인자를 토대로 투수성구조영역과 수리암반영역으로 세분화하여 연구지역의 불규칙하고 복잡한 지하수유동체계를 해석해 보고자 하였다. 지하공동 내에서 확인된 단열분포특성과 지하공동굴착과 동시에 지표관측공 28개를 통해 측정된 지하수위 및 수평수벽공 95개와 수직수벽공 63개에 의해 일별로 계측된 압력 및 주입량을 통해 연구지역은 지하수의 방벽역할을 하는 3개의 투수성구조영역과 4개의 수리암반영역으로 구분이 가능하였다. 공동심도에 발달된 투수성 구조는 국지적 큰 규모 단열대인 NE-1과 2개의 국지규모 단열대로 구성되고 있으나, 수리암반영역은 국지규모 단열대에 의하여 4개영역으로 구분된다. FZ-2 구조대와 인접한 수리암반영역 Domain-A와 B는 수평수벽공의 초기압이 최대 약 15 kg/cm2까지 높으며, 지하공동 굴착 시 상·하부의 지하수위변화의 차이가 10 ~ 40 m로 상·하부의 수리적 연결성이 양호한 것으로 평가된다. 반면, FZ-1 구조대와 인접한 Domain-C와 D는 이중수위측정시설 설치 시 상부와 하부의 지하수위차는 최대 약 120 m로 매우 크게 나타났으며, 상부지하수는 공동굴착 시 수위가 크게 변화하지 않았다. Domain C, D의 하부암반의 수리전도도(7.2 × 10(-10) m/sec)는 상대적으로 낮은 지하수 함양량의 원인을 제공하고 있으며, 연속체개념의 지하수유동모델링을 통해 계산된 4개영역의 함양량은 연구지역의 20년간 평균 강수량(1,356 mm/year)의 2 %로 계산되었다. This study aims to evaluate a complex groundwater flow system around the underground oil storage caverns using the concept of hydraulic compartment. For the hydrogeological analysis, the hydraulic testing data, the evolution of groundwater levels in 28 surface monitoring boreholes and pressure variation of 95 horizontal and 63 vertical water curtain holes in the caverns were utilized. At the cavern level, the Hydraulic Conductor Domains(fracture zones) are characterized one local major fracture zone(NE-1)and two local fracture zones between the FZ-1 and FZ-2 fracture zones. The Hydraulic Rock Domain(rock mass) is divided into four compartments by the above local fracture zones. Two Hydraulic Rock Domains(A, B) around the FZ-2 zone have a relatively high initial groundwater pressures up to 15 kg/cm2 and the differences between the upper and lower groundwater levels, measured from the monitoring holes equipped with double completion, are in the range of 10 and 40 m throughout the construction stage, indicating relatively good hydraulic connection between the near surface and bedrock groundwater systems. On the other hand, two Hydraulic Rock Domains(C, D) adjacent to the FZ-1, the groundwater levels in the upper and lower zones are shown a great difference in the maximum of 120 m and the high water levels in the upper groundwater system were not varied during the construction stage. This might be resulted from the very low hydraulic conductivity(7.2 × 10(-10) m/sec) in the zone, six times lower than that of Domain C, D. Groundwater recharge rates obtained from the numerical modeling are 2% of the annual mean precipitation(1,356mm/year) for 20 years.

신라 왕경 석조유구의 용도 연구

장우영 고조선단군학회 2023 고조선단군학 Vol.52 No.-

Stone storage facilities, which are analyzed to be low-temperature storage facilities with underground water in mind, arelikely to bestoragecontainers, given that they are close to large buildings, located on the east and northwest sides of the building site, and and small storage containers were excavated. In addition, in the case of Buyeo Gwanbuk-ri site, chestnut bark, semi-branch fragments were found in the lowest organic layer in the storage facility, and a large amount of Roof tile were excavated inside the facility. In some cases, stone remains are classified as toilets other than storage functions due to their various shapes and arrangements in the sites. They are far from large buildings, Near walls, Outside walls and Excavated relics do not have storage containers. Even if natural science analysis is difficult due to a limited excavation, it is suggested to collect the soil inside the reservoir when the soil survey is completed during theinvestigation stage and request parasite egg analysis and fine soil analysis during the report stage.

지하수 유동 영향에 따른 지하수 이용 열펌프 시스템의 대수층 온도 변화 예측 모델링

심병완(Shim, Byoung-Ohan),송윤호(Song, Yoon-Ho) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06

Aquifer Thermal Energy Storage (ATES) can be a cost-effective and renewable geothermal energy source, depending on site-specific and thermohydraulic conditions. To design an effective ATES system having influenced by groundwater movement, understanding of thermo hydraulic processes is necessary. The heat transfer phenomena for an aquifer heat storage are simulated using FEFLOW with the scenario of heat pump operation with pumping and waste water reinjection in a two layered confined aquifer model. Temperature distribution of the aquifer model is generated, and hydraulic heads and temperature variations are monitored at the both wells during 365 days. The average groundwater velocities are determined with two hydraulic gradient sets according to boundary conditions, and the effect of groundwater flow are shown at the generated thermal distributions of three different depth slices. The generated temperature contour lines at the hydraulic gradient of 0.00 1 are shaped circular, and the center is moved less than 5m to the groundwater flow direction in 365 days simulation period. However at the hydraulic gradient of 0.01, the contour center of the temperature are moved to the end of boundary at each slice and the largest movement is at bottom slice. By the analysis of thermal interference data between two wells the efficiency of the heat pump system model is validated, and the variation of heads is monitored at injection, pumping and no operation mode.

Steady seepage simulation of underground oil storage caverns based on Signorini type variational inequality formulation

Yunfeng Dai,Zhifang Zhou 한국지질과학협의회 2015 Geosciences Journal Vol.19 No.2

To analyze the seepage characteristics of water-sealed underground oil storage caverns, a calculation software was programmed based on the Signorini type variational inequality formulation. The storage region and boundary condition of oil-groundwater contact surface were generalized, and a two-dimensional numerical simulation model of finite-element method was built. The seepage characteristics and the water inflow of oil storage caverns were analyzed, while the conditions of different oil levels in caverns with water curtain system were taken into account. The effect of a water curtain system was assessed, and the design parameters of water curtain system such as width, water pressure, borehole space, and elevation were evaluated. The seepage simulation model was applied to estimate the seepage field and water inflow of the Huangdao underground oil storage caverns during the future operation period.