Experimental and Numerical Analysis of the Effects of Clay Content on CH₄ Hydrate Formation in Sand

Abstract

Natural gas hydrates exist in large quantities in nature and represent a potential source of energy, mostly in the form of methane gas. Knowledge about hydrate formation in clayey sand is of importance for understanding the production of methane gas from hydrate reservoirs, as well as for understanding the impact of global warming on the stability of subsurface gas hydrates. In this paper, we explore the effect of clay content on methane gas hydrate phase transitions in unconsolidated sand at realistic reservoir conditions (P = 83 bar and T = 5–8 °C) both experimentally and numerically. Kaolin clay was mixed in pure quartz sand in a series of experiments where the clay content ranged from 0 wt % to approximately 12 wt %. Simulations of these experiments were set up in TOUGH+HYDRATE. In the kinetic reaction model, particle size was used as a proxy for kaolin content. The growth of methane hydrates from water (0.1 wt % NaCl) and methane were visualized and quantified by magnetic resonance imaging with millimeter resolution. Dynamic imaging of the sand revealed faster hydrate growth in regions with increased clay content. NMR T 2 mapping was used to infer the hydrate phase transition characteristics at the pore scale. Numerical simulations showed also faster growth in materials with a smaller mean particle size. The simulation results showed a significant deviation throughout the hydrate growth period. The constraints of both the experimental and modeling setups are discussed to address the challenges of comparing them.

Mechanical Properties of Gas Hydrate-Bearing Sediments Influenced by Multiple Factors: A Comprehensive Review of Triaxial Tests

“…As clay content increases, fine clay particles fill pores between sediment particles, and sediment porosity varies under different clay content conditions. When clay content exceeds a certain threshold, the mode of hydrate distribution in sediments changes, altering original contact types between sediments. , Due to the ability of clay to adsorb and fix water molecules, the higher the clay content in sediments, the higher the adsorption of pore structure and clay surface, and less water available for sediments to form hydrates . The adsorption and hydration of clays affect the synthesis and distribution of hydrates as well as the pore structure between sediment particles.…”

Physio-Chemical and Mineralogical Characteristics of Gas Hydrate-Bearing Sediments of the Kerala-Konkan, Krishna-Godavari, and Mahanadi Basins

“…The high number of clay particles decreases the pore space and the accumulation of hydrates. The presence of Kaolin clay may inhibit the formation of methane hydrate [52].…”

Pore Water Conversion Characteristics during Methane Hydrate Formation: Insights from Low-Field Nuclear Magnetic Resonance (NMR) Measurements

“…The continuous increase in methane hydrate caused the continuous decrease in water signal intensity, but the decrease was different at different positions. Therefore, hydrates also exhibited heterogeneous spatial distribution in clayey-silty sediments [35,36]. In summary, current researchers using MRI technology mainly focus on the hydrate distribution characteristics and the evolution laws of hydrate saturation during the hydrate formation.…”