Peyman Pourafshary

Quantification of Density-Driven Natural Convection for Dissolution Mechanism in CO 2 Sequestration

Dissolution of CO2 into brine causes the density of the mixture to increase. The density gradient induces natural convection in the liquid phase, which is a favorable process of practical interest for CO2 storage. Correct estimation of the dissolution rate is important because the time scale for dissolution corresponds to the time scale over which free phase CO2 has a chance to leak out. However, for this estimation, the challenging simulation on the basis of convection–diffusion equation must be done. In this study, pseudo-diffusion coefficient is introduced which accounts for the rate of mass transferring by both convection and diffusion mechanisms. Experimental tests in fluid continuum and porous media were performed to measure the real rate of dissolution of CO2 into water during the time. The pseudo diffusion coefficient of CO2 into water was evaluated by the theory of pressure decay and this coefficient is used as a key parameter to quantify the natural convection and its effect on mass transfer of CO2. For each experiment, fraction of ultimate dissolution is calculated from measured pressure data and the results are compared with predicted values from analytical solution. Measured CO2 mass transfer rate from experiments are in reasonable agreement with values calculated from diffusion equation performed on the basis of pseudo-diffusion coefficient. It is suggested that solving diffusion equation with pseudo diffusion coefficient herein could be used as a simple and rapid tool to calculate the rate of mass transfer of CO2 in CCS projects.

Remediation of colloid-facilitated contaminant transport in saturated porous media treated by nanoparticles

Facilitation of contaminant transport in porous media due to the effect of indigenous colloidal fine materials has been widely observed in laboratory and field studies. It has been explained by the increase in the apparent solubility of low soluble contaminants as a result of their adsorption on the surface of fine particles. Attachment of colloidal fine particles onto the rock surface could be a promising remedy for this challenge. In this experimental study, the effect of five types of metal oxide nanoparticles, γ-Al2O3, ZnO, CuO, MgO, and SiO2, on suspension transport was investigated. In several core flooding tests, different nanofluids were used to saturate the synthetic porous media. Subsequently, after sufficient soaking time, the suspension was injected into the treated porous media. Analysis of the effluent samples’ concentration by Turbidimeter apparatus demonstrated that the presence of nanoparticles on the rock surface resulted in a significant reduction in fine concentrations in the effluent samples compared with non-treated media; ZnO and γ-Al2O3 demonstrated the best scenarios among the tests performed in this study. In order to characterize the surface properties of the treated porous media, the zeta potential of the surface was measured. Results showed that the treated porous media acts as a strong adsorbent of fine particles, which are the main carrier of contaminants in porous media. These findings were quantitatively confirmed by calculation of the total energy of interaction between the fine particles and rock surface using the Derjaguin–Landau–Verwey–Overbeek theory.

Scaling Analysis of the Convective Mixing in Porous Media for Geological Storage of CO2: An Experimental Approach

Prediction of the behavior of convective mixing and the effectiveness of this mechanism is essential for permanent sequestration of CO2 in deep saline aquifers. Simulation of the diffusion–convection mechanism at a large scale is very expensive and time-consuming; therefore, scaling relationships can be used to find suitable candidates for storage sites. In this study, scaling analysis is performed for the convective mixing of CO2 in saline aquifers based on experimental results. The scaling relationships are presented for the prediction of convective dissolution behavior. In the presented scaling analysis, different systems with a wide range of Rayleigh numbers were used. All experiments were conducted in a dissolution cell with different ranges of grain sizes. The pressure decay data are used to determine the dissolution rate of CO2, Sherwood number, and convective flux. In addition, the fraction of ultimate dissolution is calculated for each experiment to investigate the mixing regimes (convective mixing and diffusive mixing). The results indicate that the mixing of CO2 in water can be approximated by a scaling relationship for the Sherwood number and convective flux. These relations can be used in the implementation of large-scale CO2 storage in deep saline aquifers.

Controlling bentonite-based drilling mud properties using sepiolite nanoparticles

Abstract Sepiolite nanoparticles were added to the bentonite-based drilling mud to control its properties, and the effects of sepiolite nanoparticles on rheological properties and filtration loss of the bentonite-based drilling mud at different temperature and pressure conditions were studied by experiments. For the bentonite-based drilling muds with and without sepiolite nanoparticles, plastic viscosity, yield point, and fluid loss were measured at different temperature and pressure conditions, the core flooding experiments were also conducted at reservoir pressure and temperatures, and fluid loss and formation damage were measured. The results show that: sepiolite nanoparticles can be used to improve the plastic viscosity and yield point of saline and fresh bentonite-based drilling mud; the bentonite-based drilling mud with sepiolite nanoparticles shows a great stability of rheological properties over a wide range of temperature and pressure, especially at high temperatures and pressures; sepiolite nanoparticles reduce the fluid loss and the permeability reduction at reservoir pressure and temperatures. Sepiolite nanoparticles are an ideal additive for bentonite-based drilling mud.

Experimental and modelling study of the solubility of CO2 in various CaCl2 solutions at different temperatures and pressures

Study of the thermodynamic behaviour of CaCl2-H2O-CO2 systems is important in different scientific areas in the chemical and petroleum engineering fields. For example, a system including salt-H2O-CO2 is a common system in CO2 geological storage. During carbonate matrix acidizing, this mixture also appears as the spent acid. Hence, study of the behaviour of this system and the solubility of CO2 in CaCl2 brine in different thermodynamic conditions is critical.In this study, CO2 solubility in 0, 1.90 and 4.80 mol/L CaCl2 solutions at 328.15 to 375.15 K and 68.9 to 206.8 bar were measured. These values are normal for oil reservoirs. A popular thermodynamic model is available in the literature for estimating the CO2 solubility in pure water and NaCl solutions. In this paper, the available model was modified by experimental work to be applicable for CaCl2 as well. Based on the measured data, the component interaction parameters in the base model were adjusted for a CaCl2-H2O-CO2 system. The developed model could predict CO2 solubility in different conditions with remarkable accuracy, particularly for high concentration solutions and at high pressures. This improvement is up to 65% better than in the base model. This model can be used in Darcy scale models for predicting wormhole propagation during carbonate matrix acidizing.

Mathematical Modeling of Colloidal Particles Transport in the Medium Treated by Nanofluids: Deep Bed Filtration Approach

A deep bed filtration model has been developed to quantify the effect of nanoparticles (NPs) on mitigating fines migration in porous media. The filtration coefficients representing the total kinetics of particles capture were obtained by fitting the model to the laboratory data. Based on the optimum filtration coefficients, the model was utilized to history match the particle concentration breakthrough profiles observed in twelve core flood tests. In the flooding experiments, the effect of five types of metal oxide NPs,

A Coupled Wellbore/Reservoir Simulator to Model Temperature Distribution and Inflow Rate Profile in Wells With Multiple Pay Zones

\upgamma \hbox {-Al}_{2}\hbox {O}_{3}

Fines Migration Control in Sandstone Formation by Improving Silica Surface Zeta Potential Using a Nanoparticle Coating Process

γ-Al2O3, CuO, MgO,