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Understanding the physical trapping mechanisms is important to design successful CO2 storage projects. Among major trapping mechanism, the dissolution trapping is mainly influenced by the mass transfer between CO2 and brine interface. A typical dimensionless number, the Sherwood number, is predicted as empirical formulas with the CO2 volume fraction and the Reynolds number. Experiments of brine imbibition into pores which are occupied by CO2 are performed with different Re and injection direction. The most active mass transfer region are consist of relative high Re and high CO2 volume fraction according to the fitting results, and the Sh decrease intensely when Re decrease, especially when Re is below 0.1. Also the descending CO2 volume fraction have relative slight impact on Sh , inducing a probably decline of values. Thus for brine in aquifers a higher migration velocity when imbibition process will accelerate the dissolution process and be benefit to the safety of reservoir. [ABSTRACT FROM AUTHOR]

Density-driven convection is known as one of the physical phenomena for CO 2 injection in saline aquifers, which accelerates the transfer of CO 2 into the groundwater, increases the dissolution rate and shorten the dissolution time, thus it is favourable for long-term CO 2 injection and the practical interest of storage security. Understanding how the occurrence and form of convective fingers is crucial to understanding the role of that Density-driven-convection behaviour. The purpose of this paper is to design a visual experimental set-up based on the MRI technique and present new analogue fluid pairs that reconstructed the convective process. The density-driven convection was formed by two miscible liquids at the interface demonstrated by fingers. We observed the development and growth of density-driven fingers of two-phase fluid i.e., water/ deuterium oxide, and brine/ deuterium oxide at different permeability porous media. Experiments indicated that the relationship of convection onset time to Rayleigh number changed with the density difference and permeability. We present an experimental study for the Rayleigh number in the range 583.279 to 2054.111. The results show that the higher permeability and density difference is conducive to shorten the convection onset time. The motivation behind this results is related to the implications for predicts the CO 2 dissolution trapping time and accumulations in geological storage of carbon dioxide. [ABSTRACT FROM AUTHOR]

As a kind of potential new sources of energy, the dissociation processes of gas hydrates using the depressurization method has been investigated by experimental observations and numerical simulations. In this study, on the basis of summarizing the existing model, a one-dimensional mathematical model containing four phase (water phase, gas phase, hydrate phase, ice phase) and three constituents (water, gas, hydrate) using the finite difference method (FDM) was established for methane hydrates decomposition by depressurization in porous media. This paper focuses on the ice generation and distribution characteristics through changing the parameters of the relevant settings, and analyzes the effect of ice generation on the pressure, temperature, permeability, cumulative gas production and other parameters. The results show that, generation of ice increases gradually in the hydrates decomposition process, and occurred early near the side area because of the large pressure gradient. The absolute permeability and instantaneous gas generation rate at the early stage decline with ice generation, and the local pressure rise. [ABSTRACT FROM AUTHOR]

Continuous increasing of CO 2 emission is observed to a main potential reason of global warning, while CO 2 geological sequestration (CGS) offers a promising technique to solve this huge environmental challenge that the world has to face today. There are, however, still some unsolved problems in CGS procedure, which is determined by pore-scale displacement mechanisms. In this study, we investigate the drainage and imbibition process of CO 2 -brine-glass beads system under reservoir conditions. A micro-focused X-ray computed tomography (micro-CT) machine with high resolution was introduced to imaging CO 2 /brine displacement and analyse the pore-scale mechanisms. The result shows that, CO 2 is continuous and brine phase remains in small pores and throats in drainage. The shape of CO 2 /brine meniscus indicates that glass beads behave intermediate wet. While in imbibition, the effect of pore-scale displacement mechanisms become significant, piston-like front was observed at pore scale, CO 2 phase is cracked and forms isolated ganglia by snap off events. [ABSTRACT FROM AUTHOR]

Abstract: CO2 flooding is the most popular recovery for oil production. It is significant to study the mechanism of the multiphase flow in porous media. In this study, experimental studies are carried out by using MRI technique to examine the detailed effects of miscibility and forces on CO2/n-decane flow in the porous medium and narrow channel. The displacing processes are conducted at various pressures and temperatures. The revolution of the distribution of decane and the characteristic of the two phase flow are investigated and analyzed. Difference between the two series tests was specified. Matrix has a great effect on the two phase flow. These experimental results give the fundamental understanding of tertiary recovery processes. [Copyright &y& Elsevier]

Abstract: Fractured reservoirs form a large percentage of the world's hydrocarbon reserves. However, in spite of their wide occurrence and huge reserves, the oil recovery from most of these reservoirs is extremely low. CO2 flooding has proven to be an efficient Enhanced Oil Recovery (EOR) method. This article addresses the use of MRI technique to follow the removal process of oil, water, supercritical CO2 multiphase flow in fractured artificial consolidated sandstone core with permeability heterogeneity at a typical reservoir temperature and pressure condition. Fluid saturation development was monitored both in the matrix and in the fractures. 2D images at various times and quantitative saturation curves were obtained during all stages of the flooding process. The fronts and interfaces between displaced and displacing fluids were also dynamics monitored in situ during water and subsequent supercritical CO2 flooding process. The results showed that the oil recovery rate can be determined by porosity, permeability and structure of the core, supercritical CO2 flooding can enhance oil recovery evidently after the water flooding. [Copyright &y& Elsevier]

Abstract: CO2 miscible flooding is one of main technologies in both the secondary and tertiary floods for Enhanced Oil Recovery (EOR). In addition, it is also an important alternative for a geological CO2 storage. In the recent twenty years, the fundamental research for visualized CO2-EOR has been launched by using mainly the Magnetic Resonance Imaging (MRI). In this study, we simulated a CO2 miscible model by using Eclipse reservoir simulation software based on the MRI coreflood test. We modified the numerical model of CO2 miscible flooding by changing the parameters to improve the CO2 miscible flood simulation results. [Copyright &y& Elsevier]

Abstract: Measurement of CO2/water two phase fluids flow in the porous media under sequestration conditions by Magnetic Resonance Imaging (MRI) technique was studied in this paper. The porous media was formed from a packed bed of glass beads. A spin echo sequence was used to measure the distribution of CO2 and water after the CO2 was injected into the porous media containing water. The displacement front was different with the packed beds. For displacement experiments in BZ-02 and BZ-2, three stages were obtained. The CO2 channeling or fingering phenomena were obviously found. Also breakthrough time was different in BZ-02 and BZ-2. The final water residual saturation depended on permeability. The larger the permeability was, the wider the front is. The distribution of CO2 was uniform in the packed beds with larger glass beads. Breakthrough occurred early. In other packed bed, the breakthrough occurred latter. The front was affected by pore porosity and permeability. The residual saturation was calculated from the intensity images. The residual saturation was inverse proportion to larger permeability, then direct proportion to flow rate. [Copyright &y& Elsevier]

Abstract: The present study provides some important thermodynamic and kinetic data for the CO2 hydrate formation in flow system. Images were obtained dynamically using Magnetic resonance imaging (MRI) system, with a fast spin-echo multi-slice scan sequence (FSEMS). The CO2 hydrate dissociation rate was quantified using MRI mean intensity of liquid water. The saturation of residual liquid water, CO2 hydrate and CO2 gas during the dissociation of CO2 hydrate were also quantified using MRI data. The highest CO2 hydrate saturation was 58% in the first process, and 26% for the second process in this investigation. [Copyright &y& Elsevier]