During CO2 storage, CO2 plume mixes with the water and oil present at the reservoir, initiated by diffusion followed by a density gradient that leads to a convective flow. Studies are available where CO2 convective mixing have been studied in water phase but limited in oil phase. This study was conducted to reach this gap, and experiments were conducted in a vertically packed 3-dimensional column with oil-saturated unconsolidated porous media at 100 bar and 50 °C (representative of reservoir pressure and temperature conditions). N-Decane and crude oil were used as oils, and glass beads as porous media. A bromothymol blue water solution-filled sapphire cell connected at the bottom of the column was used to monitor the CO2 breakthrough. With the increase of the Rayleigh number, the CO2 transport rate in n-decane was found to increase as a function of a second order polynomial. Ra number vs. dimensionless time τ had a power relationship in the form of Ra = c×τ−n. The overall pressure decay was faster in n-decane compared to crude oil for similar permeability (4 D), and the crude oil had a breakthrough time three times slower than in n-decane. The results were compared with similar experiments that have been carried out using water.

CO2 convective mixing in saline aquifers has been widely studied numerically and experimentally. Reservoir heterogeneity is significant for CO2 convective mixing and experimental studies are still limited. In this study, we have conducted a visualization of CO2 convective mixing experiments in heterogeneous porous media at reservoir conditions using CO2 and water. We have used a two-dimension Hele-Shaw cell, different glass beads of different permeability at porous media, and water solution with pH indicator. Glass beads were packed in a different way (horizontally and vertically) to generate the heterogeneity inside the test cell. We have studied transport velocity deviation due to the heterogeneity and effects of permeability transition zone together with the effects of boundary conditions. It was found out that having a low permeable layer below a high permeable layer restructure the flow of CO2 fingers and dampens the CO2 transport velocity. With the vertical permeability zones, having a high permeability zone accelerates CO2 gravity transport through that zone which is a good representation for a fracture or a fault in the reservoir. CO2 convection onset is governed by the vertical high-permeable layer. Boundary conditions have been dominant with the presence of high permeable zones. It also found out that the experimental results presented in this study match with the simulation studies that are available in the literature. (c) 2021 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

CO2 convective mixing in water has been visualized in Hele-Shaw and PVT cell experiments but not at the pore scale. Furthermore, CO2 convective mixing in a three-phase system (i.e., CO2 in the presence of both water and oil) has not been visually investigated. A vertically placed micromodel setup was used to visualize CO2 convective mixing at 100 bar and 50 °C, representative of reservoir conditions. To the best of our knowledge, for the first time, we have visually investigated CO2 convective mixing in water at the pore scale and also CO2 convective mixing in a multiphase system (water and oil). CO2 mixing in water governed by both diffusion and convection mechanisms was observed. The vertical CO2 transport velocity was calculated to be 0.3 mm/min in both a 100% water saturation system and a residual oil-saturated system. First, CO2 always found the easiest path through the connected pores, and then CO2 was transported into less connected pores and dead-end pores. CO2 transport into dead-end pores was slower than through the preferential path. CO2 transport into water-filled ganglia with trapped oil was observed and was slower than in water.

CO2 convective mixing has been extensively studied for CO2 dissolution in saline water but very limited with the presence of oil. The objective of this work was to visually study the supercritical CO2 (sCO2) dissolution and convective mixing into oil at realistic reservoir temperature and pressure conditions with and without the presence of porous media. A specially designed high-pressure 2D-cell was used to investigate the sCO(2) mixing into oil phases. Schlieren imaging method was used as the visualization method. The experiments were carried out at 100 bar and 50 degrees C using n-octane, n-decane, and crude oil as the main oils. Porous media with different permeability was prepared using glass beads. Convective fingering was found to accelerate the mixing of CO2 with n-octane and n-decane. It was not possible to visualize the CO2 convective fingering in crude oil due to the low opacity of the oil phase. The CO2 dissolution into oil phases was quite instantaneous and fast without the presence of porous media. The swelling of oil was measured as 55%, 50% and 11% for n-decane, n-octane and crude oil respectively without the presence of porous media. Boundary effects were affecting the CO2 mixing due to the circular shape of the 2D-cell. Having a water layer below the oil layer tends to dampen the CO2 transport from the oil phase to the water phase. CO2 dissolution into oil saturated porous media was slower compared to that without the presence of porous media. The mixing of CO2 was faster at higher permeability than at lower permeability. Visualization of CO2 convective mixing/fingers inside oil-saturated porous media using a Hele-Shaw cell yet to be achieved experimentally.

When CO2 is injected into aquifers, CO2 will dissolve into the water phase. CO2 dissolution initiated by diffusion, will increase the density of the water phase and thereby commence the convective flow of CO2. The objective of the presented work was to visually investigate the effects of permeability on the convective mixing of super-critical CO2 with water at realistic reservoir conditions (pressure and temperature). This required construction of a high-pressure transparent Hele-Shaw cell that allowed visualization of CO2 transport, and the development of experimental procedures. To develop the high-pressure Hele-Shaw cell, stress/strain calculations and simulations were carried out to select the best building materials for realistic working pressure and temperature and required dimensions to study convection. Porous media of different permeabilities were prepared using glass beads of different sizes. The experiments were carried out at 100 bar and 50 degrees C using a deionized water solution with Bromothymol blue (BTB) as pH indicator. In the constructed Hele-Shaw 2D-cell, the cell volume was formed by two glass plates separated by an adjustable spacer. In the present study, the cell thickness was 5.0 mm in the main part of the cell volume. The high-pressure Hele-Shaw cell has made it possible to investigate CO2-dissolution and mixing with water at pressures and temperatures realistic for CO2-storage reservoirs in a porous medium for the first time. CO2 mixing and finger initiation in the water phase without the presence of porous media was an instantaneous process. The rate for CO2 dissolution and mixing with water was found to increase with increasing permeability. The CO2 dissolution pattern was found to depend on the permeability. Fingering of CO2-rich high density water was observed with the highly permeable porous medium. Piston-like displacement was observed in lower permeable porous medium.

During the CO2 injection for EOR and/or storage, CO2 will be dissolved into the fluid phases present in the reservoirs. This will change the density of these phases, and thereby introduce convective flow which will accelerate the CO2 dissolution. Several visualization experiments are reported in the literature to observe CO2 dissolution and gravity driven processes with and without porous media and at different conditions (pressure and temperature). In the presented study, a low-pressure 2D-cell (Hele-Shaw type) experimental set-up was constructed to evaluate the design and develop experimental procedures. Preliminary experiments were carried out at 10 bar/22 °C to visualize CO2 dissolution in porous media of different permeability and wettability conditions. Fingering was visible without porous media and in high permeable porous media. A high-pressure (150 bar) cell for experiments at supercritical CO2 conditions, has been designed based on the experience and the results obtained with the low-pressure experimental cell.

mixed-wet porous media. In the study of wettability, some fingers were observed only in water-wet porous media. Additional oil production was observed when carbonated water was introduced to water-wet and mixed-wet porous media. Tertiary carbonated water spontaneous imbibition didn`t show much difference compared to secondary carbonated water spontaneous imbibition. Keywords: Spontaneous imbibition, Improved oil recovery, Fingers, Visualization, Permeability, Wettability, Carbonate water Novelty: • Formation of carbonated water fingers inside porous media is significant at higher permeability, especially pronounced at water-wet conditions • Visual observation has proved that carbonated water injection has potential to improve the oil production

The main aim of this study was to determine the available heat in the cement kiln exhaust gas subject to different process conditions. A Norwegian cement plant producing about 1.3 million tons of cement per year was used as a case study. A mass and energy balance was made for the raw meal department, and process data available from the plant process database as well as manually measured gas flow rates were used to calculate the available heat. The available heat can be utilized by a combination of low pressure (LP) steam generation and hot water generation. It was found that waste heat is 1.5–4.2 MW for LP steam generation and 2.2–5.8 MW for hot water generation. The variation in available heat is due to different raw meal types being produced, requiring different gas inlet temperatures to raw meal mill. In cases when no raw meal is produced (in maintenance shutdown periods), all the gas will bypass the mill, and approximately 20 MW of LP steam and 6 MW of hot water can be generated. The heat loss from the system was estimated based on measurements, and the fan power inputs were calculated. Both were found to be negligible compared to the available heat. Furthermore, the total false air coming into the system was estimated as 40–50% of the total gas flow rate going out from the raw meal department.

The aim of this study is to determine minimum fluidization velocity of three different particles which represent different Geldart classification groups and to compare the results with computational results.The experiments were conducted using a fluidized cylindrical cold bed with uniform air distribution.The three particulate materials use were zirconia, bronze, and steel, classified as Geldart A, B and D particles, respectively, and the minimum fluidization velocities were found to be 0.015, 0.07 and 0.27 m/s, respectively.Using the commercial CPFD software Barracuda, the fluidized system was simulated using the Wen-Yu and Wen-Yu-Ergun multiphase flow models.The CPFD-determined minimum fluidization velocities for zirconia, bronze, and steel were found to be 0.008, 0.08 and 0.23 m/s, respectively, corresponding quite well with the experimental results for Geldart B and D particles.