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Controls on Periodicity of CO₂-Driven Cold-water Geyser: Tenmile Geyser in Utah
Jize Piao,Weon Shik Han,Kue-Young Kim,Eungyu Park 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
In geologic CO₂ sequestration (GCS), one of the primary concerns is that stored CO₂ leaks to the surface through unexpected pathways such as abandoned wells and fractures. The leakage of CO₂ not only reduces the efficiency of the GCS projects but also causes noticeable damage to the environment and ecosystem. As a natural analog of CO₂ leakage from geological storage facilities, a CO₂-driven cold-water geyser, defined as periodically ejection of cold water (< 20°C) by ascending CO₂ bubbles, is brought into focus in GCS projects. Although the individual eruption process can be explained by the two-phase flow, including water and gaseous CO₂, the trigger point of eruption and the periodicity remain unclear. To accurately clarify the leakage mechanism, this study analyzed time-series datasets of Tenmile geyser (four datasets: measurements in 2011, 2013, 2014, and 2015) located in the Green River area, Utah, which is famous as naturally leaking CO₂ site. In the measurements, the eruption duration (ED) and the interval between two consecutive eruptions (IBE) were identified by pressure changes. The mean ED and IBE values were 9.76 ± 0.10 min and 8.42 ± 0.21 hr, respectively. For finding the trigger point in each eruption cycle, hydrostatic pressure was forcibly decreased by pumping to induce eruptions. Four artificial explosive eruptions were initiated when the pressure dropped to 7.27 kPa, 11.08 kPa, 11.33 kPa, and 14.41 kPa. In the naturally driven eruptions, such slight decreases in hydrostatic pressure occurred during IBEs, and the lengths of IBEs were significantly related to the variations in atmospheric pressure (Pair ) and temperature (Tair ). The considerable variations in Pair and Tair associated with desert weather caused significant variations in geyser periodicity. For example, the geyser erupted more frequently at low Pair and high Tair, and IBE was shortened. Therefore, we suggest that atmospheric conditions should be considered in addition to geologic and wellbore conditions to quantify CO₂-driven cold-water geysers accurately.
Piao, Jize,Han, Weon Shik,Choung, Sungwook,Kim, Kue-Young Hindawi Limited 2018 Geofluids Vol.2018 No.-
<P>For investigating the wellbore flow process in CO2 injection scenarios, coupled wellbore-reservoir (WR) and conventional equivalent porous media (EPM) models were compared with each other. In WR model, during the injection, conditions for the wellbore including pressure and temperature were dynamically changed from the initial pressure (7.45-8.33 MPa) and temperature (52.0-55.9°C) of the storage formation. After 3.35 days, the wellbore flow reached the steady state with adiabatic condition; temperature linearly increased from the well-head (35°C) to the well-bottom (52°C). In contrast, the EPM model neglecting the wellbore process revealed that CO2 temperature was consistently 35°C at the screen interval. Differences in temperature from WR and EPM models resulted in density contrast of CO2 that entered the storage formation (~200 and ~600 kg/m<SUP>3</SUP>, resp.). Subsequently, the WR model causing greater density difference between CO2 and brine revealed more vertical CO2 migration and counterflow of brine and also developed the localized salt-precipitation. Finally, a series of sensitivity analyses for the WR model was conducted to assess how the injection conditions influenced interplay between flow system and the localized salt-precipitation in the storage formation.</P>
A Stochastic Model Optimization for SVE Well Remediation Considering Multiphase Fluid Behavior
( Taehoon Kim ),( Weonshik Han ),( Jize Piao ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2
NAPL (Non-aqueous phase liquid) is a typical pollutant causing soil and groundwater pollution. NAPL often contains VOCs (Volatile Organic Compounds) such as TCE (Trichloroethylene), PCE (Tetrachloroetylene), aromatic hydrocarbons, etc. As a method for removing volatile gases, Soil Vaor Extraction (SVE) method is commonly used. In this study, complex multiphase fluid behavior was simulated using TOUGH2 / TMVOC, then applied this mechanism to the actual situation and tried to study the optimization method of soil and groundwater remediation by using a SVE well. After constructing the conceptual model based on characteristics in Deokso farm site, it is assumed that the LNAPL (Light Non-aqueous phase liquid) component including VOCs is leaked from surface to subsurface environment. Subsequently, the model was simulated until the leaked pollutants are removed by the SVE well. In order to cover a large number of model results and reduce the time for executing a full-physics model, we adopted a stochastic surrogate model which is generally used for the model optimization. Finally, objective functions related to the VOCs mass residual and the Gas/Oil ratio were generated based on the numerical model results, which takes into account the well location, the bottom-hole pressure and the steam injection rate. We confirmed that the predicted value from the objective functions matches the simulation result (R<sup>2</sup>=0.99, 0.97, respectively). For expanded research, the optimal remediation solution using Generic Algorithm (GA) method will be utilized.
논문 : 지하수 모니터링 이상변동 자료를 이용한 소규모 지진 영향 유추
우남칠 ( Nam C Woo ),( Jize Piao ),이재민 ( Jae Min Lee ),이찬진 ( Chan Jin Lee ),강인옥 ( In Oak Kang ),최두형 ( Doo Houng Choi ) 대한지질공학회 2015 지질공학 Vol.25 No.1
이 연구는 국내에서 운용되고 있는 지하수 장기관측망의 자동 관측자료를 이용하여, 발생빈도가 상대적으로 높은 M3.0내외의 소규모 지진에 의한 영향과 지진 전조현상에 의한 지하수의 변화 관측 및 구분가능성을 평가하고자 수행되었다. 사용된 지하수 관측자료는 2012년 4월~6월 기간의 1시간 단위로 김천지좌, 강진성전, 공주정안 3개 관측소의 암반관측공에서 관측된 자료이다, 지하수위, 수온 및 EC 값의 시계열 자료에서 부분적으로 급격한 이상변동이 관측되었으며, 이변동은 2012년 5월 30일 경북 영덕에서 발생한 M3.1 지진의 전조와 그 영향으로 해석된다. 그럼에도 불구하고 지진의규모 및 발생위치와 관측공까지의 거리와 지하수 변동의 크기는 선형관계를 보이지 않으며, 이는 관측공 자체의 구조적 특성과도 연관된다. 따라서 지진관측을 고유목적으로 하는 관측공의 설치, 운용이 필요하며, 이를 통한 장기적 모니터링은 지진 재난지역에서의 비상수자원 확보와 지하공간 안전성 확보의 기반정보를 제공할 수 있을 것이다. This study tests the potential of detecting small-magnitude earthquakes (~M3.0) and their precursors using a long-term groundwater-monitoring database. In groundwater records from April to June 2012, abnormal changes in water level, temperature, and electrical conductivity were identified in the bedrock monitoring wells of the Gimcheon- Jijwa, Gangjin-Seongjeon, and Gongju-Jeongan stations. These anomalies could be attributed to the M3.1 earthquake that occurred in the Youngdeok area on May 30th, although no linear relationship was found between the scale of changes and the distance between each monitoring station and the epicenter, which is attributed in part to the wide screen design of the monitoring wells. Groundwater monitoring networks designed specifically for monitoring earthquake impacts could provide better information on the safety of underground space and on the security of emergency water-resources in earthquake disaster areas.
이병선,명우호,오세봉,전성천,박길택,송성호,Lee, Byung Sun,Myoung, Wooho,Oh, Sebong,Jun, Seong-Chun,Piao, Jize,Song, Sung-Ho 한국지하수토양환경학회 2020 지하수토양환경 Vol.25 No.1
This study was conducted to examine an artificial recharge system, which was considered to be an alternative for securing additional groundwater resources in a high-density greenhouse region. An injection well with a depth of 14.0 m was placed in an alluvial plain of the zone. Eight monitoring wells were placed in a shape of dual circles around the injection well. Aquifer tests showed that the aquifer was comprised with high-permeable layer with hydraulic conductivities of 1.5×10<sup>-3</sup>~2.4×10<sup>-2</sup> cm/sec and storage coefficients of 0.07~0.10. A step injection test resulted in a specific groundwater-level rising (Sr/Q) values of 0.013~0.018 day/㎡ with 64~92% injection efficiencies. Results of the constant-rate injection test with an optimal injection rate of 100 ㎥/day demonstrated an enormous storage capacity of the alluvial aquifer during ten experimental days. To design an optimal recharge system for an artificial recharge, the high-permeable layer should be isolated by dual packers and suitable pressure should be applied to the injection well in order to store water. An anisotropy ratio of the alluvial aquifer was evaluated to be approximately 1.25 : 1 with an anisotropy angle of 71 degrees, indicating intervals among injection wells are almost the same.