Tae‐Hyuk Kwon

This study reviews the fundamental mechanisms of biological soil improvement methods—microbially induced calcium carbonate precipitation (MICP) and biopolymer treatment (BPT). Extensive experimental data on various geotechnical properties of sands treated by MICP and BPT are compiled, including the unconfined compressive strength, Mohr-Coulomb shear strength parameters, and permeability. Furthermore, the variations in these engineering parameters are correlated to calcium carbonate content for M

Hydrate‐bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling/production operations or intentionally as part of gas extraction from the hydrate itself. In all cases, high pore fluid pressure generation is anticipated during hydrate dissociation. A comprehensive formulation is derived for the prediction of fluid pressure evolution in hydrate‐bearing sediments subjected to thermal stimulation without mass transfer. The formulation co

Direct use of naturally occurring microbes for soil improvement has recently gained attention due to their ubiquitous and versatile characteristics in subsurface soil. Microbes produce soft and sticky extracellular polymeric substances (or biopolymers) that are known to alter the hydrological characteristics of soils; however, the mechanisms and extent of such soft biopolymers in altering soil erosion resistance remain scarcely explored. This study explored the role of microbial biopolymers in s

Natural gas hydrates are found widely in oceanic clay-rich sediments, where clay-water interactions have a profound effect on the formation behavior of gas hydrates. However, it remains unclear why and how natural gas hydrates are formed in clay-rich sediments in spite of factors that limit gas hydrate formation, such as small pore size and high salinity. Herein, we show that polarized water molecules on clay surfaces clearly promote gas hydrate nucleation kinetics. When water molecules were pol

Natural and artificial gas hydrates with internal pores of nano to centimeters and weak grain-cementation have been widely reported, while the detailed formation process of grain-cementing hydrates remains poorly identified. Pore-scale morphology of carbon dioxide (CO2) hydrate formed in a partially brine-saturated porous medium was investigated via X-ray computed microtomography (X-ray CMT). Emphasis is placed on the pore-scale growth patterns of gas hydrate, including the growth of dendritic h

The construction of underground tunnels can prime or trigger ground subsidence, and thus surface deformation monitoring is required during and post-construction. Freely available satellite data allow significant possibilities for the use of remote sensing techniques, particularly multi-temporal interferometric synthetic aperture radar (Mt-InSAR), for surface deformation monitoring. However, track records and field demonstrations of InSAR-based tunneling-related deformation monitoring are limited

Abstract Depressurization of hydrate‐bearing sediments (HBS) can cause the movement of fine particles, and in turn, such fines migration affects fluid flow and mechanical behavior of sediments, ultimately affecting long‐term hydrocarbon production and wellbore stability. This study investigated how and to what extent depressurization of HBS causes fines migration using X‐ray computed tomography (CT) imaging. Methane hydrate was synthesized in sediments with 10% fines content (FC), composed of sa

Capillarity in small, confined pores has a pronounced effect on the depression of the dissociation temperature of gas hydrates, known as the Gibbs–Thomson effect. However, this effect remains poorly understood in natural fine-grained sediments with wide pore size distributions. This study investigated the effect of pore size distributions of fine-grained sediments on the dissociation temperature of a gas hydrate. A gas hydrate was synthesized under partially water-saturated conditions in nanosiz

Replacement of methane with carbon dioxide in hydrate has been proposed as a strategy for geologic sequestration of carbon dioxide (CO(2)) and/or production of methane (CH(4)) from natural hydrate deposits. This replacement strategy requires a better understanding of the thermodynamic characteristics of binary mixtures of CH(4) and CO(2) hydrate (CH(4)-CO(2) mixed hydrates), as well as thermophysical property changes during gas exchange. This study explores the thermal dissociation behavior and

Development of synthetic aperture radar (SAR) technology and the dedicated suite of processing tools have aided the evolution of remote sensing techniques for various Earth Observation (EO) applications. Interferometric SAR (InSAR) is a relatively new geodetic technique which provides high-speed and reliable geographic, geologic, and hazards information allowing the prognosis of future environmental and urban planning. In this study, we explored the applicability of two differential interferomet

This study addresses a numerical approach for exploring how thermal change destabilizes marine gas hydrate-bearing sediments. The underlying physical processes of hydrate-bearing sediments, such as hydrate dissociation, self-preservation, pore pressure evolution, gas dissolution, and sediment volume expansion, are incorporated with the thermal conduction, pore fluid flow, and mechanical response of sediments. Two-dimensional numerical modeling is conducted using a verified finite difference meth

Modification of oil–brine–minerals interfacial properties with biosurfactant-producing microorganisms and their extracellular metabolites has been considered as one of the viable strategies for microbial enhanced oil recovery (MEOR). In this study, the effect of lipopeptide biosurfactant produced by Bacillus subtilis on the interfacial tension (IFT) and wettability in oil–brine–mineral systems was quantitatively examined by monitoring dodecane–brine IFT and the contact angle of a dodecane–brine–