Novel Pore-Scale Visualization during CO₂ Injection into CH₄ Hydrate-Saturated Porous Media

Abstract

A better understanding of the mobility of the CO2 phase and the sweep within the CH4 hydrate-bearing sediments is required for the success of CO2 storage and concurrent CH4 production. In this work, we investigate the injectivity of CO2 in CH4-hydrate-saturated porous media and the subsequent dissociation of CH4 / CO2 mixed hydrate at the pore level. A total of six pore-scale visualization experiments were performed using a high-pressure water-wetted silicon wafer-based micromodel whose pore network resembles a cross section of sandstone. Liquid CO2 was injected at a constant volumetric rate of 0.2-0.5 ml / hour at a high saturation of CH4 hydrate (SH = 0.81-0.99) at P = 59-69 bar and T = 3.3-4.5°C. The results confirmed the presence of two different hydrate arrangements at the end of the CO2 injection, such that the hydrate phase change and liquid distribution were influenced by the invasion behaviour of the liquid phase and the initial distribution of CH4 hydrate. Invasion of the CO2-rich liquid phase resulted in the formation of massive hydrates without residual liquid saturation. While the CH4 rich liquid phase invaded the hydrates and produced an excess of the liquid phase in the field of view. Later, massive hydrates were dissociated by stepwise depressurization, with multiple dissociation and reformation recorded between the thermodynamic stability pressure of pure CH4 hydrates and pure CO2 hydrates, supported by the presence of the liquid phase. Continuous mobilization of liquid phase and mixing of liquid and gas phases led to localized hydrate reforming below the CH4 hydrate stability pressure. This is the first pore-scale visualization of CO2 injection into CH4-hydrate saturated porous media and ManuscriptClick here to view linked References demonstrates the feasibility of combining CO2 Injection into CH4 hydrate with stepwise depressurization to produce CH4 gas.

2022 Pioneers in Energy Research: John Ripmeester

“…The study by Xu et al reported that the production well should be in the upper layer of the reservoir for larger particle size sediments, whereas for sediments with smaller particles, the production well should be located in the bottom layer of the reservoir. Pandey et al evaluated the effects of the liquid CO 2 injection on the evolution of morphology in the CH 4 hydrate system based on pore-level visualization. The findings are relevant to the proposed CO 2 injection into CH 4 hydrate as a novel approach to store CO 2 while generating CH 4 .…”

“…Pandey et al evaluated the effects of the liquid CO 2 injection on the evolution of morphology in the CH 4 hydrate system based on pore-level visualization. The findings are relevant to the proposed CO 2 injection into CH 4 hydrate as a novel approach to store CO 2 while generating CH 4 . Li et al combined microfocus X-ray computed tomography and a pore network model to investigate the effect of hydrate dissociation on gas trapping and hysteresis in capillary pressure in different wettability systems.…”

Perspectives of CO2 Injection Strategies for Enhanced Oil Recovery and Storage in Indian Oilfields

“…Wolfcamp shales (high carbonate) show an increased pore volume, which is potentially good for storage. Pandey et al 35 utilized a powerful tool and found that CO 2 injection dissolves some initial hydrate and moves liquid around and free gas, and slow injection takes longer to plug pores, which is good for CO 2 capture. Gao et al 36 delves into injecting CO 2 in tight oil, which can be a doubleedged sword.…”