초록 ▼

최종목표
○ 시추공 기반 심지층(1-5 km, 고온고압환경) 특성규명 InDEPTH 요소기술 개발
- 심지층(1-5 km) 특성화율 70% 확보
- 고온고압용 5 km급 물리검층 시스템 운영/복합해석 기술 개발
- 연속체(OpenGeoSys)기반 THM 복합 거동해석 모듈 개발 및 적용

개발내용 및 결과
○ 실험실 고온고압조건(170℃, 100 MPa)에서의 열물성 자료 측정/분석 기법 확립
○ 국내 심도별 지온분포도 작성 및 암석 열물성 자료의 공간통계분석
○ 국내 고온성 온천수의

최종목표
○ 시추공 기반 심지층(1-5 km, 고온고압환경) 특성규명 InDEPTH 요소기술 개발
- 심지층(1-5 km) 특성화율 70% 확보
- 고온고압용 5 km급 물리검층 시스템 운영/복합해석 기술 개발
- 연속체(OpenGeoSys)기반 THM 복합 거동해석 모듈 개발 및 적용

개발내용 및 결과
○ 실험실 고온고압조건(170℃, 100 MPa)에서의 열물성 자료 측정/분석 기법 확립
○ 국내 심도별 지온분포도 작성 및 암석 열물성 자료의 공간통계분석
○ 국내 고온성 온천수의 열/수리물리적 특성 분석기법 확립
○ 고온, 고압, pH 조건하 균열암석의 투수특성 변화에 대한 주요 영향 변수 연구
○ 고심도 조건 암반절리내 점성유체 유동특성 분석기술 개발
○ 불연속 절리 암반 내 차수그라우팅 최적 설계기술 개발
○ 암반구조물 장기안정성 평가 프레임워크와 수치해석 모델 개발
○ 고지압하 암반구조물의 굴착 모델링기법과 균열대 형성/제어를 위한 동적재하 모델링기법 개발
○ DESTRESS(독일 GFZ 외): 미소진동 자료의 복합 해석을 통한 심부 균열 저류층 특성화 기술 개발
○ 암반강도 추정을 위한 역해석 기법 개발 및 적용성 분석
○ 고온고압 환경에서 시추공내 유체/지반 특성 파악을 위한 계측과 복합해석, 검층 시스템 심부 현장에의 적용과 개선
○ 개발된 3차원 초기응력 측정장치의 실내/현장 검증과 상용화 추진
○ 심지층 스케일에서의 적용을 위한 THM 모듈 확장과 연계해석 수치 모델링 기법 검증
○ DECOVALEX-2019(미국 LBNL 외): 유체주입에 의한 단층의 수리역학적 연계거동 해석기법 개발(Fault slip modeling, step 3)
○ FRACOD(호주 CSIRO 외): 파괴역학 기반 T-H-M code 개발/검증

기대효과
○ 1–5 km급 시추공 기반의 심지층 특성 규명(높은 응력/온도/수압 조건)을 통한 지구환경 및 에너지자원산업분야의 기반기술 확보
○ 에너지/환경 문제해결과 지각재해에 대한 신뢰 있는 안전 확보와 국민편익 증진
○ 심지층 공간 개발, 활용의 핵심기술 국산화를 통한 대외 경쟁력 강화

적용분야
○ 고준위방폐물 심층처분, 심부 시추공 처분(5 km 이상), 심부 단층조사, 셰일가스 개발, CO₂ 지중저장, 심부 채광
○ 심지층 공간 구축을 위한 타당성 조사 및 부지선정
○ 심지층 에너지저장(CNG/CAES) 및 지하연구시설(천체우주물리 관측 실험실)과 같은 중요 심지층 공간의 Long-term 안전설계

(출처 : 요약서 4p)

Abstract ▼

Ⅳ. Results of the Work
The thermal properties (thermal conductivity, volumetric heat capacity, and thermal diffusivity) of rocks under high temperature and high pressure conditions were measured by using the TPS2500S instrument of Hot Disk. The thermal conductivity and the thermal diffusivity of

Ⅳ. Results of the Work
The thermal properties (thermal conductivity, volumetric heat capacity, and thermal diffusivity) of rocks under high temperature and high pressure conditions were measured by using the TPS2500S instrument of Hot Disk. The thermal conductivity and the thermal diffusivity of rocks at high temperature decreased with increasing temperature, while the volumetric heat capacity of rocks increased with increasing temperature. On the other hand, the thermal conductivity and the volumetric heat capacity of the rocks under high pressure increased, while he thermal diffusivity of rocks decreased. Finally, the thermal conductivity and the thermal diffusivity of the rocks under high temperature and high pressure conditions decreased with increasing temperature and pressure, and the volumetric heat capacity of rocks increased. This change in thermal properties of rocks according to the temperature and pressure conditions is a typical features of crystalline rocks and it will be helpful to understand the thermal state of the deep subsurface.

By collecting the rock sample of the data-deficient area, we established the spatial database of rock thermal properties and the thematic map of geothermal distribution according to depth. For the first half, we collected 25 rock samples in the area of Muan-Mokpo-Jindo. Later, we collected 25 rock samples in the area of Gunsan-Iksan-Jinan-Geochang. Then we measured thermal properties(density, porosity, thermal diffusivity, specific heat, thermal conductivity, heat productivity). Moreover, 43 samples of rock samples were collected and thermal properties were measured for Jeongup area, which is a vulnerable area. On the other hand, Statistical analysis was performed on 3661 rock properties. The thermal conductivity is in the range of 0.75 to 9.03 W/mK, with an average of 3.26 W/mK and a median of 3.09 W/mK. Statistical analysis of the hotspot and cold spot distribution of rock thermal properties shows that the topographic maps of Busan and Daejeon are sufficient hotspots with a scale of 250,000. Finally, we established the mobile system of geothermal resources information based on multi-platform. This system includes the hybrid app, open-source GIS, user management service, Naver mesh-up, user-defined layer and GIS common functions.

Geothermal and hydraulic physical properties of deep wells drilled for hot spring development were analyzed. The mean geothermal slop of Korea is about 26 ℃/km, which is lower than the geothermal slop where the flow of the hot spring water moves from the bottom to the top. Analysis of the temperature logging data of Changwon Mageumsan5 suggests that the hot spring water is stored deeper than the depth of the drilled hole. In the pumping test, the drawdown in the well is composed of the sum of the aquifer loss part and the well loss part. The well loss index of the hot springs developed in 2018 is 2-11.8, which is much larger than the value of 2 interpreted in the porous media.

The main objective of this project is to examine the important factors controlling changes in the permeability of fractured rocks that result from the coupled thermal-hydraulic-mechanical-chemical(THMC) effects. The changes of the permeability have been be investigated through a series of flow-through experiments, using various rocks of granite, sandstone and mudstone under different temperature, stress, and permeant pH conditions. In 2017, the circulation-flow experiment was conducted. Moreover, a further-modified model was developed for predicting the evolution in permeability and reactive transport behavior within single rock fractures, and the comparison results between the experimental measurements and the prediction by the developed model was submitted to the International Journal of Rock Mechanics and Mining Sciences, which is now under review.

The purpose of this study is to improve the reliability of rock graft optimal injection design around deep underground facilities through experimental and numerical identification of viscous fluid flow and distribution patterns in discontinuous rock at deep depth conditions. Design and fabrication of factor analysis related to flow characteristics, high pressure injection test apparatus and high temperature viscosity measuring instrument were completed. In the second year, the effect of high-pressure conditions on the viscous fluid penetration distance was analyzed through the nonlinear correlation of pressure-flow rate in rock fracture obtained from the high-pressure injection test of viscous fluid. The effect of high temperature on the penetration distance of viscous fluid was quantitatively analyzed through simulation.

We have developed technology and framework for long-term stability evaluation of rock mass structure. Three long-term stability model(2D and 3D FDM and 2D DEM based models) by applying fracture mechanics and damage mechanics theory were developed.
Compared with the long-term stability evaluation results obtained by the previous laboratory subcritical crack growth tests with the developed models, the developed models properly simulated the delayed failure shown in the tests and the delayed failure time agreed well with the test results. In addition, the trend of AE hits from modeling was compared with test results and it was found that the model simulated the AE increase before the failure of rock specimen. Therefore, it can be utilized as a basic data for establishing long-term stability monitoring methodology with criteria based on AE/MS technology.

Two bend test methods called the half ring (HR) test and split ring (SR) test were applied to measuring the tensile strength of rock materials. The concepts of both tests are the same except that the fracture line is perpendicular to the loading direction in the case of the SR test. Owing to this perpendicularity, it was believed that the SR test could be more accurate than the HR test. As with the HR specimen, the SR specimen is also a curved prismatic bar. The practical tensile strength of these special bars can be obtained by analytical formulas in mechanics of materials. At first, the applicability of the two tests to rock materials was examined through LS-DYNA numerical simulations. The accuracy obtained from the simulations was 12%, 1% and 5% for the HR, tensile SR, and compressional SR tests, respectively. Associated laboratory tests, however, showed a completely different result. It was found from the experiments that the ratios of the tensile strength of the tensile and compressional SR tests were only 1.2-1.4 and 1.1-1.2, respectively, with respect to the corresponding Brazilian strength. This ratio values are too small to be accepted although only a few samples have been tested. Hence, it is concluded that the SR test should not be recommended for use in practice. In contrast, the corresponding ratio of the HR strength was found to be 1.7-2.0, which coincides well with the theory.

Interpretation techniques has been developed for microseismic data from the hydraulic stimulation tests and applied to analysis on the crack propagation behavior in deep reservoirs during hydraulic stimulation. We have developed the algorithm for additional detection of microseismic events by applying the Matched filter method, and also performed various analysis on the events that occurred during hydraulic stimulation by applying various location methods.

To develop an inverse analysis technique for estimating the properties of rock mass at depth, the present study investigated and compared the existing optimization methods to solve the objective function of inverse problems. A ground displacement-based inverse analysis was proposed that can estimate the strength of the surrounding rock mass in underground excavation. A simulation tool was developed to combine the search algorithm with a numerical code for excavation analysis. Based on a synthetic underground excavation example, we investigated the applicability of the present inverse analysis to identifying the rock mass strength parameters and proposed a strength estimation method.

The purpose of this study is to construct the essential infrastructure necessary for deep underground utilization and development. For the first year development, a 5 km long winch system and high temperature and high-pressure PTS (temperature/pressure/natural gamma/flow/caliper) logging system was built and field tests were completed for 5 km deep boreholes. In the second year work, the field test was performed by applying the PTS logging and the imaging logging to the borehole with a depth of 4 km, thereby improving the logging system. In the third year, technology independence was attempted by constructing a large-diameter caliper logging and a cement bond logging system.

A new device was developed to replace the existing 3D rock stress measuring device.
This device consists of data storage module and measurement module. By installing a data logger in the data storage module, the measurement data can be stored continuously in real time. The piston triggering system eliminates unnecessary lines, improving work reliability and convenience. Resin discharge test, rock core test, and rock block test were performed to verify the development equipment. The resin ejection test confirmed that the data logger was working exactly as designed. The rock core and block tests also confirmed that the strain gage's metrology performance was met.

In this study, we developed a numerical module as a tool for researching to consider the various domestic field and subsurface conditions. In the first year, we combined OpenGeoSys that handles fluid mechanics and thermodynamics with FLAC3D for mechanical analysis. In this module development, we design OpenGeoSys as a master and FLAC3D as a slave via a file-based sequential coupling. In the second year, we have chosen Terzaghi’s consolidation problem as a benchmark model to verify the proposed module, and the comparative results between the analytical solution and numerical analysis showed a good agreement. In the third year, we conducted a simulation for the Otway project to check the applicability on the subsurface scale, and the results matched well with the previous reports. Further, we composed a platform based on open-source programs for effective utilization of the developed module, including the process of mesh generation, numerical simulation, and post-processing of the results, and verified the capability of the platform.

The present study is aimed at developing a numerical model to reproduce coupled hydro-mechanical processes associated with fault reactivation by fluid injection in low permeability rock, as part of the DECOVALEX-2019 project Task B. We proposed a modeling approach using coupled fluid flow and mechanical interface model through benchmark calculations for well defined models, and demonstrated its applicability by reproducing field experiment results obtained at the Mont Terri Rock Laboratory in Switzerland. It was found that the proposed model can capture the process of fracture opening and propagation, and thus provide a reasonable prediction of the hydro-mechanical behavior associated with fault reactivation by fluid injection. It is expected that this modeling approach can be applied to various fault hydraulic models tailored to suit field observations.

The FRACOD Phase III project(2016 ~ 2019), which was conducted for three years as an international collaboration R&D project, aims to develop and validate the fracture mechanics analysis codes that can simulate the T-H-M coupled behavior in fractured rock masses. Thirteen institutions in seven countries, which participated in the FRACOD project, presented and discussed their research and results for the three years. Each participant has successfully undertaken the tasks as originally planned. An important achievement of this joint international R&D project was the publication of the “Modeling Rock Fracturing Processes and Applications” book, which contains information on rock fracture process modeling and application examples. During the project period, we successfully hosted the international workshop on fracturing geomechanics and the annual project meeting in different countries each year. This has resulted in an international network for research cooperation in the field of rock mechanics and rock engineering.

(출처 : SUMMARY 15p)

목차 Contents

• 표지 ... 1제 출 문 ... 2최종보고서 요약서 ... 4요 약 문 ... 6SUMMARY ... 12CONTENTS ... 20목차 ... 22제1장 연구개발과제의 개요 ... 24 제1절 연구개발의 목적 및 필요성 ... 24 1. 연구개발의 목적 ... 24 2. 연구개발의 필요성 ... 24 제2절 연구개발 범위 ... 25제2장 국내외 기술개발 현황 ... 32 제1절 심부 지하 활용 현황 ... 32 1. 국외 현황 ... 32 2. 국내 현황 ... 39 3. 국내외 시장 현황 ... 41 제2절 심지층 공간 활용을 위한 심지층 특성화 관련 특허 현황 ... 42 1. 기술개발 분야 특허 동향 ... 42 2. 국가별 특허 동향 ... 42 3. 기술별 동향 ... 43제3장 연구개발수행 내용 및 결과 ... 44 제1절 심지층(1-5 km) 특성화율 70% 확보 ... 44 1. 실험실 고온고압조건(170℃, 100 MPa)에서의 열물성 자료 측정/분석 ... 44 2. 국내 심도별 지온분포주제도 작성 및 암석 열물성 자료의 공간통계분석 ... 51 3. 국내 고온성 온천수의 열/수리물리적 특성 분석기법 확립 ... 65 4. 고온, 고압, pH 조건 하 균열암석의 투수특성 변화에 대한 주요 영향변수 연구 ... 85 5. 고심도조건 암반절리내 점성유체 유동특성 분석기술 개발 ... 96 6. 불연속 절리 암반 내 차수그라우팅 최적 설계기술 개발 ... 113 7. 암반구조물 장기안정성 평가 프레임워크와 수치해석 모델 개발 ... 204 8. 고지압/고변형률 속도조건에서 암석의 취성파괴 모델링을 통한 파열특성 규명 ... 221 9. 미소진동 자료를 이용한 수리자극 균열 거동 파악기술 개발 ... 241 10. 암반강도 추정을 위한 역해석 기법 개발 및 적용성 분석 ... 251 제2절 고온고압용 5 km급 물리검층 시스템 운영/복합해석 기술 개발 ... 269 1. 고온고압 환경에서 시추공내 유체/지반 특성 파악을 위한 계측과 복합해석 및 검층 시스템 심부 현장에의 적용과 개선 ... 269 2. 개발된 3차원 초기응력 측정장치의 실내 또는 현장 검증과 상용화 추진 ... 281 제3절 연속체기반 T-H-M 연계해석 모듈 개발 및 적용 ... 292 1. 심지층 스케일에서의 적용을 위한 T-H-M 모듈 확장과 연계해석 수치 모델링 기법 검증 ... 292 2. 유체주입에 의한 단층 활성화 및 수리-역학적 연계거동 해석:　DECOVALEX-2019 TASK B ... 316 3. FRACOD(호주 CSIRO 외): 파괴역학 기반 T-H-M code 개발/검증 ... 342제4장 목표달성도 및 관련분야에의 기여도 ... 362 제1절 목표달성도 ... 362 1. 최종 연구목표의 달성도 ... 362 2. 당해 연도 목표의 달성도 ... 362 제2절 관련분야에의 기여도 ... 364 1. 기술적 측면 ... 364 2. 경제·산업적 측면 ... 364 3. 정책적 측면 ... 364제5장 연구개발결과의 활용계획 ... 366제6장 연구개발과정에서 수집한 해외과학기술 정보 ... 368 제1절 해외 연구동향 ... 368 제2절 논문 ... 370제7장 참고문헌 ... 374끝페이지 ... 386