초록 ▼

최종목표
◦ 대륙붕 내 100만 톤/연 규모 CO₂ 지중저장 후보지 5개소 제시
◦ 국내 현무암층의 CO₂ 광물 탄산화 능력 평가 및 급속 탄산화 지화학적 제어 인자 규명

개발내용 및 결과
◦ 서해와 남해 대륙붕에서 10개 후보지(소분지, 현무암 대지 대상)를 도출하고 잠재성을 평가하여 우선순위 제시
◦ 서해 군산분지 동 소분지, 남해 남해도 소분지가 서해와 남해에서 우선순위가 높고, 이론적 저장용량은 각각 약 20억톤, 12억 톤으로 평가되었음
◦ 서해

최종목표
◦ 대륙붕 내 100만 톤/연 규모 CO₂ 지중저장 후보지 5개소 제시
◦ 국내 현무암층의 CO₂ 광물 탄산화 능력 평가 및 급속 탄산화 지화학적 제어 인자 규명

개발내용 및 결과
◦ 서해와 남해 대륙붕에서 10개 후보지(소분지, 현무암 대지 대상)를 도출하고 잠재성을 평가하여 우선순위 제시
◦ 서해 군산분지 동 소분지, 남해 남해도 소분지가 서해와 남해에서 우선순위가 높고, 이론적 저장용량은 각각 약 20억톤, 12억 톤으로 평가되었음
◦ 서해안 발전소 포집, 군산분지 동 소분지 저장에 대한 경제성 예비분석 결과, 연 300만 톤 25년 운영 시, CO₂톤당 저감비용은 87.47 USD/tCO₂으로 추정됨
◦ 지구화학 모델링(현무암-CO₂-물-암석 반응 모델링)을 통한 제어인자 도출: pH 범위는 6보다 크고 8보다 작은 것이 현무암 탄산화에 효과적임
◦ 반응 실험을 통한 제어인자 도출: 반응온도가 pH, 압력 보다 탄산화 반응에 미치는 영향이 큼, 용액 내 Fe이온 또는 시료 표면의 산화물형태의 Fe의 존재는 Mg의 용출을 방해하는 요인으로 작용
◦ 실험에서 확인한 온도, pH, 광물이온 조절요인은 분자동역학 모델링(위탁)에서도 확인

기대효과
◦ 2030년 국가 온실가스 감축 목표(연간 400만 톤) 달성에 기여
◦ 국가 CO₂ 지중저장 용량 평가 기초자료로 활용
◦ 대규모 CCS 통합실증 사업 저장 후보지 선정 및 평가에 활용

적용분야
◦ 향후 국가 CCS 종합 추진 계획 개정 등에 기초자료로 활용
◦ 대규모 CCS 통합실증 사업 및 2030년 상업적 규모 CCS 사업 지중저장소 확보를 위한 탐사 및 시추 평가에 활용

(출처 : 요약서 5p)

Abstract ▼

Ⅲ. Results
III-1. Suitability assessment of potential area for a large-scale CO₂ storage
□ Analysis of physical properties of drill cuttings from existing wells in the Yellow Sea (West Sea) and the South Sea
◦ The porosity is exponentially reduced with depth and the reduction rat

Ⅲ. Results
III-1. Suitability assessment of potential area for a large-scale CO₂ storage
□ Analysis of physical properties of drill cuttings from existing wells in the Yellow Sea (West Sea) and the South Sea
◦ The porosity is exponentially reduced with depth and the reduction rate is dependent on rock type.
◦ The porosity of mudstone is reduced by 4 times faster than the rate of sandstone with depth.
◦ No overpressure is expected according to the exponent of consolidation in all kinds of rock types.
◦ Geologic formations of mostly sandstone with ~20% of porosity at ~1,900m depth from the Inga-1 well in Gunsan basin can be suggested for CO₂ storage.
◦ Sandstone layers with 25~30% of porosity occur at 1,000~1,500m depth JDZ V-1 and JDZ VII-2 in the Juju Basin.

□ Basin-scale evaluation of CO₂ storage capacity for the Gunsan Basin in the West Sea of Korea
◦ This study presents a basin-scale suitability assessment of a large-scale CO₂ storage for offshore subbasins in the Gunsan Basin relatively close to CO₂ emission source on the west coast of Korea.
◦ The six subbasins were largely filled by the Cretaceous to Eocene non-marine deposits with a thickness up to ca. 6 km. Storage capacity for the Cretaceous to Eocene unit in each subbasin is assessed using USDOE’s method, widely accepted for deep aquifers in an open system.
◦ Probabilistic distribution of the storage capacity is estimated from the range of uncertainty in an individual parameter such as N/G, porosity, CO₂ density, and storage efficiency. The 50th percentile storage capacity in the basin reaches ca. 4,221 Mt.
◦ The East Subbasin has the largest storage capacity of 1,935 Mt (P50) which can be sourced from the nearby coal-fired power plant.

□ Basin-scale evaluation of CO₂ storage capacity for sub-basalt geological formation and sedimentary basin in the South Sea of Korea
◦ Two basalt flow structures were found around the PZ-1 well in the basement high of the Southern Continental Shelf (West Sea) of Korea through seismic and well data evaluation.
◦ Basalt flow structures, which overlying saline formations suitable for CO₂ geological storage, distributed over 85 km² and 125 km² in area.
◦ As a result of constructing 3D geological model and evaluating the storage capacity using U.S. DOE (2008) method, the storage capacities of the basalt flow structures are an average of 81.50 MtCO₂ (42.07~143.79 MtCO₂) and 74.90 MtCO₂ (37.81~129.20 MtCO₂), respectively.
◦ A large basalt flow structure (~ 680 km²) was found for the first time, off the eastern coast of Jeju Island through new marine seismic survey.
◦ CO₂ storage capacity of basalt flow structure near Jeju Island is estimated as 726.22 MtCO₂ (363.11~1,240.62 MtCO₂).
◦ CO₂ storage capacities on basin-scale for the Dragon and Namhaedo sub-basins are estimated as 9,564.78 MtCO₂ (4,782.39~16,339.83 MtCO₂) and 1,235.76 MtCO₂ (617.88~2,111.09 MtCO₂), respectively.

□ Economic analysis of large-scale CO₂ geological storage in Korea
◦ The cost of the CCS project is estimated to be about 106 and 88 USD/tCO₂ (avoided) for 22 and 30 years of operation, respectively.
◦ The introduction of CCS has a relatively high impact on industries such as machinery/equipment and chemical products.
◦ The production inducing effects of CCS is found to have a high influence factor, indicating a large backward linkage effect.
◦ The effects on the whole Korean economy is estimated for 3 cases - total case and operating costs only case and the case where the energy cost is minimized due to the use of renewable energy.

□ Impact of a long-term CO₂ injection on pressure change and its behaviour
◦ This study investigates the pressure change and its mechanism during the long-term injection of carbon dioxide in a storage formation with a closed boundary condition, considering sedimentary basins in Korea.
◦ Numerical modeling (TOUGH2) and approximate solution are applied to briefly examine linear behaviors.
◦ The pressure rise in closed boundary conditions can be categorized in two stages along with time: 1) pressure propagation stage and 2) compression stage.
◦ The pressure rise during the propagation stage is proportional to log (t), whereas the rise during the compression stage is proportional to t.
◦ Therefore, it is necessary to investigate the geological conditions that can evaluate the size and boundary conditions of the reservoir candidates during the exploration of candidates reservoir for the commercial-scale storage site in Korea.
◦ Results of the studies can provide guidelines related to the size of the sedimentary basin and pressure criteria required for the selection of commercial scale geological storage, and for long-term injection design.

□ Experimental analysis of core-scale CO₂ migration behavior
◦ Multiphase flow tests were conducted at a core-scale to understand the migration behaviors of CO₂ and water in a stratified geologic media (sandstone interbedded with silt).
◦ A core-flooding apparatus combined with an X-ray scanning system provided high-resolution experimental dataset of continuous data on the differential pressure (ΔP) across a core plug and CO₂ saturation maps over time.
◦ During the multiphase flow tests, we captured dynamic fluctuation in ΔP as CO₂ front advanced by displacing water through different geologic media. The spatio-temporal evolution of CO₂ saturation in each geologic media revealed two increasing stages, implying that the capillary pressure of the downstream geologic media affects the upstream CO₂ saturation.
◦ In addition, multiphase transport simulations were conducted to assess the sensitivity of model parameters. Permeability and porosity were respectively sensitive to pressure and CO₂ saturation. Overall, the parameters of the silt layer were more sensitive to the pressure and CO₂ saturation build-up compared to those of the sand layer.
◦ Additionally, history matching was conducted to validate the model by sequentially matching ΔP and CO₂ saturation within the stratified system.
◦ Finally, we extended the core-scale modeling work further to field-scale and investigated the impact of boundary conditions and heterogeneity on both pressure and CO₂ saturation distribution.

□ Analysis of fault stability
◦ Analysis of mineral composition and grain size for the faults encountered in the TB3 hole drilled at the Pohang branch of KIGAM.
◦ Measurement of frictional properties (e.g., friction coefficient, a–b, and critical slip distance) of the fault rocks.
◦ The fault rocks extracted from the TB3 hole consist of 50~60% clay minerals (mainly kaolinite) and 40~50% sedimentary clasts (e.g., quartz and feldspar).
◦ The friction coefficient is measured in the range of 0.2~0.3 which is significantly low and attributed by the high clay contents.
◦ The a–b value is negative which is attributed by the high clay contents, indicating that the fault slip, if any, would be aseismic.

□ Soil CO₂ monitoring
◦ Baseline soil gas composition and CO₂ flux were monitored before CO₂ injection at the demonstration site in Pohang branch. The purposes of this monitoring was to secure and confirm that there will be no leakage through soil during and after the CO₂ injection and to develop soil monitoring technologies.
◦ Soil CO₂ monitoring technologies were applied at natural analogue site near CO₂-rich water wells and spring in Daepyeong, Sejong city. Regional distribution of vadose zone CO₂ concentration and CO₂ flux were measured. A site which was anomalous high CO₂ concentration and CO₂ flux was found, and time-series measurement was performed.
◦ In addition, CO₂ flux measurement was performed to determine whether the soil CO₂ flux showed a significant change due to mechanical stimulation like earthquake. Preliminary experiments were conducted in KIGAM to determine the measurability and to review the requirements and limitations for further research.

III-2. Study on key factors controlling CO₂ rapid mineral carbonation in basalt
□ Experimental evaluation of mineral carbonation in basalt rock
◦ In order to investigate the mechanism of mineral carbonation in the basaltic storage site, the simulation experiment was performed using Jeju basalt samples in the autoclave. Magnesite was produced under the following conditions: 6 months (reaction time), 100℃ (reaction temperature) and 75 bar (a partial pressure of CO₂). In particular, white carbonate minerals, which are a sign of mineral carbonation, are observed outside of water, while red iron oxide is developed inside of water. This result is consistent with the result of increase of activation energy during Fe doping (see commissioned research report).

□ CaCO₃ phase transformation
◦ The purpose in the study is to produce basic data for CaCO₃ phase transformation that can be occurred in CO₂ geologic storage. The experiment on CaCO₃ phase transformation was conducted by using an effect of additive. The range of n value in amorphous CaCO₃(ACC, CaCO₃·nH₂O) was calculated baed on thermal analysis of initially synthesized CaCO₃. Through the study, we have tried to produce and interpretate basic data for CO₂ carbonation process after injection of the large amount of CO₂.

□ Porosity change of basaltic tuff by CO₂-water-rock interaction
◦ The batch experiment for CO₂-water-rock interaction was conducted under CO₂ pressure of 100 bar and temperature of 25 ℃ during 84 days.
During the experiment, fluid was sampled for chemical analysis periodically. Before and after the experiment, basaltic tuff was analyzed by XRD, SEM-EDS, CT, and surface area. The results showed that the increase in porosity of basaltic tuff because of mineral dissolution such as zeolites. In addition, calcite precipitation was not observed in this study. It may be because calcium was removed from the fluid by ion exchange and incorporated into smectite. However, long term observation is needed to identify the relationship between porosity change and the stability of caprock.

□ Effect of CO₂ concentration on microbial community and chemical processes
◦ For the evaluation of the effect of CO₂ concentration on microbial community and geochemical processes, reaction bottles were filled with groundwater and basalt under CO₂ partial pressure of 0 psi, 3 psi, 10 psi, and 20 psi. Lactate was added as a sole electron donor. The experiment was carried out for 87 days. The result showed that sulfate reduction occurred 0 psi and 3 psi condition but sulfate reduction did not occur under 10 psi and 20 psi. In the basalt samples under 3 psi, FeS precipitate was observed because of sulfate reduction. This experimental results indicated that sulfate reduction consumed Fe ion as iron sulfide mineral not as iron carbonate mineral. Thus inhibition of sulfate reduction may be more favorable to mineral carbonation in the view of CO₂ storage.

□ Geochemical modeling for identifying factors controlling mineral carbonation
◦ This study aims to identify the controlling parameters for mineral carbonation of basalt rocks using kinetical geochemical modeling. For geochemical modeling, temperature conditions were 25 ℃, 50 ℃, and 80 ℃ and pressure conditions were 10 bar, 50 bar, and 100 bar of CO₂ partial pressure. A fluid composition was 0.5M NaCl. The result showed that CO₂ pressure affected reaction kinetics controlling pH and temperature affected the amount of solubility of minerals. Under pH 8, new precipitated minerals were mostly Ca-Mg-Fe carbonates(carbonate solid solution). Above pH 8, calcite was precipitated as carbonate minerals. However, zeolites and clay minerals were also precipitated. This indicated that above pH 8 Ca consumption was competed by calcite and zeolite/clay mineral. Thus appropriate pH range for CO₂ storage may be from pH 6 to pH 8.

□ Study on control factor of CO₂ carbonation via multi-scale simulation
◦ This study aims to estimate an ion dissolution mechanism on mineral surface using density functional theory (DFT) and to investigate the effect of temperature and hetero-metal atom on dissolution mechanism.
From the study, we used PNC (pre-nucleation cluster) formation to identify the factor of carbonate rate under basaltic and underground condition. And the control factor of carbonation such as temperature, pressure, pH, and type of added mineral ions(Ca2⁺, Fe2⁺) was estimated through comparison of PNC formation rate.

(출처 : SUMMARY 13p)

목차 Contents

• 표지 ... 1
• 제 출 문 ... 3
• 최종보고서 요약서 ... 5
• 요 약 문 ... 7
• S U M M A R Y ... 13
• CONTENTS ... 21
• 목차 ... 23
• 제1장 연구개발과제의 개요 ... 25
• 제1절 연구개발의 목적 및 필요성 ... 25
• 제2절 연구개발 범위 ... 28
• 제2장 국내외 기술개발 현황 ... 31
• 제3장 연구개발수행 내용 및 결과 ... 37
• 제1절 대규모 CO2 지중저장 후보지 잠재성 평가 ... 37
• 1. 서해 및 남해 대륙붕 시추암편 암상 분석 ... 37
• 2. 서해 및 남해 시추공 시추암편 물성 분석 ... 63
• 3. 서해 잉어-1 공의 시추암편 공극크기분포도 및 모세관압 분석 ... 83
• 4. 서해 군산분지 CO2 저장용량 평가 ... 88
• 5. 남해 대륙붕 소분지 및 현무암 대지 저장용량 평가 ... 100
• 6. 서해 및 남해 대규모 CO2 지중저장 후보지 우선순위 평가 ... 122
• 7. 국내 대륙붕 대규모 CO2 지중저장 경제성 분석 ... 132
• 8. 대규모 CO2 주입에 따른 분지규모 압력 변화 양상과 기작 ... 142
• 제2절 포항센터 실증부지 특성화 및 모니터링 ... 163
• 1. 코어 스케일 CO2 저장능력 분석 연구 ... 163
• 2. 단층 역학물성 분석 연구 − 포항센터 실증부지 잠재 단층 ... 177
• 3. 토양 CO2 모니터링 연구 − 포항센터 실증부지 배경 모니터링 ... 186
• 4. 비포화대를 통한 CO2 누출 자연유사 연구 ... 195
• 5. 역학적 자극에 따른 근지표 CO2 거동 변화 평가 예비 실험 ... 204
• 6. CO2 주입/관측 시나리오 설계 연구 ... 208
• 제3절 현무암의 CO2 급속 탄산화 지구화학적 제어 인자 도출 ... 216
• 1. 현무암 광물 탄산화 반응 실험 결과 ... 216
• 2. CO2 확산을 이용한 탄산화 상변환(비정질에서 결정질) 과정 실험 및 현상 분석 ... 241
• 3. CO2-암석-물 반응에 의한 현무암질 응회암의 공극률 변화 ... 248
• 4. CO2 농도가 현무암-물-미생물 반응에 미치는 영향 예비 연구 ... 255
• 5. CO2 급속 탄산화 제어 인자 도출 지구화학 모델링 ... 266
• 6. 다차원 전산모사를 이용한 CO2 탄산화 제어인자 연구 ... 273
• 제4장 목표달성도 및 관련분야에의 기여도 ... 287
• 제5장 연구개발결과의 활용계획 ... 295
• 제6장 연구개발과정에서 수집한 해외과학기술정보 ... 297
• 제7장 참고문헌 ... 303
• 끝페이지 ... 316