Effect of Permeability on Hydrate-Bearing Sediment Productivity and Stability in Ulleung Basin, East Sea, South Korea

Abstract

Methane hydrate has attracted attention as a next-generation resource, and many researchers have conducted various studies to estimate its productivity. Numerical simulation is the optimal method for estimating methane gas productivity. Meanwhile, using a reasonable input parameter is essential for obtaining accurate numerical modeling results. Permeability is a geotechnical property that exhibits the greatest impact on productivity. The permeability of hydrate-bearing sediment varies based on the sediment pore structure and hydrate saturation. In this study, an empirical permeability model was derived from experimental data using soil specimens from the Ulleung Basin, and the model was applied in numerical analysis to evaluate the sediment gas productivity and ground stability. The gas productivity and stability of hydrate-bearing sediments were compared by applying a widely used permeability model and the proposed model to a numerical model. Additionally, a parametric study was performed to examine the effects of initial hydrate saturation on the sediment gas productivity and stability. There were significant differences in the productivity and stability analysis results according to the proposed permeability model. Therefore, it was found that for accurate numerical analysis, a regional permeability model should be applied.

Hydrate Dissociation Evaluation and Stratum Subsidence Response Induced by Depressurization in Hydrate-Bearing Permafrost

“…Additionally, for point C, under the action of the upper soil’s weight, the hydrate dissociation leads to soil settlement. As the consolidation pressure exerted by the upper soil gradually decreases, when it is smaller than the initial consolidation pressure, the deformation of the bottom soil will slowly swell and finally reach a stable state …”

“…As the consolidation pressure exerted by the upper soil gradually decreases, when it is smaller than the initial consolidation pressure, the deformation of the bottom soil will slowly swell and finally reach a stable state. 48 As shown in Figure 10a, for point A, the greater the reservoir permeability, the more severe the settlement deformation. It is inferred that the gas dissipation is faster because of the higher soil permeability, resulting in a speedier consolidation rate during the mining process.…”

Numerical Simulation of Gas Hydrate Production Using the Cyclic Depressurization Method in the Ulleung Basin of the Korea East Sea

“…The experimental results of relative permeability were validated with results of X-ray CT (Computerized Tomography), and it represented good matching results [33]. Furthermore, even though the intrinsic permeability was different with each soil specimen, the permeability reduction trends with increasing hydrate saturation were similar for all samples, and the N values of Figure 7 represent the porosity [34]. Table 1.…”

“…The range of hydrate saturation is 38.8~86.2%. Moreover, we adopted experimental data of the relative permeability curve and permeability model, using a core sample from UBGH2-6, as illustrated in Figures 6 and 7 [33,34]. The experimental results of relative permeability were validated with results of X-ray CT (Computerized Tomography), and it represented good matching results [33].…”

Geomechanically Sustainable Gas Hydrate Production Using a 3D Geological Model in the Ulleung Basin of the Korean East Sea

“…Research of gas hydrate has been broadly conducted in various scientific and industrial fields, such as energy recovery, CO 2 capture and storage, gas separation, water desalination, gas storage and transport [2]. Gas hydrate is stable under high-pressure and low-temperature conditions [3]. Accordingly, gas hydrate deposits are found in permafrost, marine sediments and deep lakes, where the pressure is over 0.6 MPa and temperature is less than 300 K at the same time [4].…”