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Local-scale variability in groundwater resources: Cedar Creek Watershed, Wisconsin, U.S.A.
Han, Weon Shik,Graham, J.P.,Choung, S.,Park, Eungyu,Choi, Woonsup,Kim, Young Sug Elsevier 2018 JOURNAL OF HYDRO-ENVIRONMENT RESEARCH Vol.20 No.-
<P>The steady-state simulation revealed that groundwater head in general was decreased toward the Lake Michigan with local variation caused by stream networks. In response to 2012 drought event, groundwater drawdown was not rehabilitated until spring 2013, implying that the aquifer required approximately 3-4 months until responding to meteorological drought. Additionally, variation in recharge caused to change in groundwater table throughout the entire aquifer simultaneously, but the effect of Lake Michigan stage on groundwater table was relatively minimal. Finally, a certain portion of streams in the Cedar Creek Watershed could be ephemeral. Switching from the RIVER to the DRAIN package for the implementation of ephemeral river and stream cells resulted in significant reduction of both groundwater head and flux, implying that realistic distribution of present groundwater head would resemble one simulated between RIVER and DRAIN packages.</P>
Han, Weon Shik,Kim, Kue-Young Elsevier 2018 Journal of petroleum science & engineering Vol.169 No.-
<P><B>Abstract</B></P> <P>A series of numerical simulations were conducted to explore the frontal speed of the CO<SUB>2</SUB> plume and residence time in the formation preserving the dipping and sinusoidal caprock. For this purpose, we generated various permutations of 2-D numerical models where the contact boundary between the caprock and targeted formation was simplified with the idealized sinusoidal function. Three parameters such as dip, amplitude, and wavelength were chosen to analyze how the dipping and sinusoidal structure could affect the frontal speed of CO<SUB>2</SUB> plume. Subsequently, the study was expanded to understand the effect of caprock permeability and the heterogeneity preserved in the storage formation.</P> <P>Simulation results under the condition of dipping caprock (2°–10°) indicated that the relationship between the migration distance of the CO<SUB>2</SUB> plume front and time followed the linear trends. Among the chosen sensitivity parameters of dip, amplitude, and wavelength, the speed of the CO<SUB>2</SUB> plume front was the most sensitive to the caprock dip, but the stored CO<SUB>2</SUB> mass varied the most significantly with the amplitude. In addition, when the caprock permeability increased, certain amounts of CO<SUB>2</SUB> escaped to the caprock, resulting in a retardation of the CO<SUB>2</SUB> plume. Similarly, in the sensitivity studies of dip, wavelength, and amplitudes, more CO<SUB>2</SUB> leaked to the caprock corresponded to smaller frontal speed of CO<SUB>2</SUB> plume. Finally, the increase in permeability heterogeneity of the targeted formation decreased the sharpness of CO<SUB>2</SUB> plume front while the mean arrival time of the plume front was relatively consistent.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Migration distance of CO<SUB>2</SUB> plume followed the linear trends under the dipping caprock. </LI> <LI> CO<SUB>2</SUB> mass varied the most significantly with the amplitude of the caprock. </LI> <LI> When the caprock k was increased, CO<SUB>2</SUB> plume front was retarded. </LI> <LI> Increase in k heterogeneity decreased the sharpness of CO<SUB>2</SUB> front. </LI> </UL> </P>
Periodic changes in effluent chemistry at cold-water geyser: Crystal geyser in Utah
Han, Weon Shik,Watson, Z.T.,Kampman, Niko,Grundl, Tim,Graham, Jack P.,Keating, Elizabeth H. Elsevier, etc 2017 Journal of hydrology Vol.550 No.-
<P><B>Abstract</B></P> <P>Crystal geyser is a CO<SUB>2</SUB>-driven cold-water geyser which was originally drilled in the late 1930’s in Green River, Utah. Utilizing a suite of temporal groundwater sample datasets, <I>in situ</I> monitoring of temperature, pressure, pH and electrical conductivity from multiple field trips to Crystal geyser from 2007 to 2014, periodic trends in groundwater chemistry from the geyser effluent were identified. Based on chemical characteristics, the primary sourcing aquifers are characterized to be both the Entrada and Navajo Sandstones with a minor contribution from Paradox Formation brine. The single eruption cycle at Crystal geyser lasted over four days and was composed of four parts: Minor Eruption (mEP), Major Eruption (MEP), Aftershock Eruption (Ae) and Recharge (R). During the single eruption cycle, dissolved ionic species vary 0–44% even though the degree of changes for individual ions are different. Generally, Na<SUP>+</SUP>, K<SUP>+</SUP>, Cl<SUP>−</SUP> and SO<SUB>4</SUB> <SUP>2−</SUP> regularly decrease at the onset and throughout the MEP. These species then increase in concentration during the mEP. Conversely, Ca<SUP>2+</SUP>, Mg<SUP>2+</SUP>, Fe<SUP>2+</SUP> and Sr<SUP>2+</SUP> increase and decrease in concentration during the MEP and mEP, respectively. The geochemical inverse modeling with PHREEQC was conducted to characterize the contribution from three end-members (Entrada Sandstone, Navajo Sandstone and Paradox Formation brine) to the resulting Crystal geyser effluent. Results of the inverse modeling showed that, during the mEP, the Navajo, Entrada and brine supplied 62–65%, 36–33% and 1–2%, respectively. During the MEP, the contribution shifted to 53–56%, 45–42% and 1–2% for the Navajo, Entrada and Paradox Formation brine, respectively. The changes in effluent characteristics further support the hypothesis by Watson et al. (2014) that the mEP and MEP are driven by different sources and mechanisms.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Changes in effluent chemistry coincide with the eruption periods at Crystal geyser. </LI> <LI> The Entrada Sandstone supplies more groundwater than previously hypothesized. </LI> <LI> The minor and major eruption periods are driven by different sources and mechanisms. </LI> </UL> </P>
Gidon Han,Weon Shik Han,Kue-Young Kim,Eungyu Park 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
Conglomerates preserving matrix and clasts caused heterogeneity such as the complex distribution of pore spaces and can eventually influence fluid flow. To evaluate the influence of complex heterogeneous features in conglomerate rock on both pore distribution and fluid flow, conglomerate cores were analyzed using X-ray computed tomography at multiresolution (i.e., voxel resolution: 1.6, 28 and 58 microns). Furthermore, to evaluate the permeability of conglomerate, three permeability estimation models such as direct method (single-phase fluid simulation), pore network model, empirical models were implemented based on X-ray CT image analysis. Conglomerate cores characterized by different distributions of matrix and clasts represented highly heterogeneous features. Such heterogeneous features caused differences in the volume of pores and changed permeabilities significantly dependent on the selected location sub-domains. In addition, through this study, the relationship between the heterogeneity and the petrophysical properties was evaluated