Propagation of surfactant and polymer flow in natural carbonate cores

This paper presents an experimental and analytical study of comprehensive effects of surfactant and polymer in aqueous solutions on the propagation in carbonates.Single-phase flow tests of surfactant,polymer and surfactant-polymer mixture were respectively conducted on natural carbonate core plugs at high temperature and high salinity reservoir conditions.The effect of different factors on chemical propagation was taken into account by use of a convection-dispersion model.The dynamic adsorptions of two amphoteric surfactants at 2000 mg/L concentration onto the carbonate rocks were 0.21 and 0.17 mg/g-rock,respectively.The dynamic adsorptions of a sulfonated polymer at 2000 and 5000 mg/L were 0.11 and 0.17 mg/g-rock,respectively.Surfactant-polymer mixtures in aqueous solutions were coinjected to evaluate their competitive adsorption,showing the surfactant adsorption was reduced by approximately 50%.The dispersion coefficient of the chemicals in the carbonate cores was in the magnitude of 10^(-3) cm^(2)/s.Caused by dispersion and adsorption,chemical concentration reduction occurred obviously during the propagation in carbonate porous media.Chromatographic separation took place in the surfactant-polymer co-injection scheme,which was estimated by modeling as well.

Experimental assessment of hybrid smart carbonated water flooding for carbonate reservoirs

Different methods of enhanced oil recovery have been used to produce trapped oil.One of these methods is carbonated water injection in which CO2 contained water is injected in reservoirs in order to decrease free CO2 injection mobility,increase water viscosity and store/remove produced greenhouse CO2 gas safely.Another enhanced oil recovery method is smart water injection at which the ions in brine are modified in order to make controlled reactions with distributed ions on the surface of rock to cause more hydrocarbon recovery.Therefore,combination of these two methods may also have a great effect on enhancing oil recovery or may result in recovery factor less than each method used alone.In this paper hybrid smart carbonated water injection method is investigated to study its applicability in oil recovery using core flooding setup.The experimental core flooding setup was designed to perform different types of EOR methods for the sake of recovery comparison with the new hybrid method.The effect of both brine content and volume of CO2 is determining in hybrid EOR assessment.The main findings of this work show that the hybrid smart carbonated water results in the highest recovery factor in comparison to the most well-known EOR methods for carbonate cores.

Composition-Dependent Mechanical and Thermal Transport Properties of Carbon/Silicon Core/Shell Nanowires

Molecular dynamics(MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires(NWs).For each concerned carbon/silicon core/shell NW with a specified diameter,it is found that elastic modulus is reduced with a linear dependence on cross-sectional area ratio.The fact matches well with the results of theoretical model.Analysis based on the cross-sectional stress distribution indicates that the core region of core/shell NW is capable of functioning as a mechanical support.On the other hand,thermal conductivity also relies on the cross-sectional area ratio of amorphous silicon shell.The core/shell interface plays a considerable influence on the thermal transport property. The decreasing rate of thermal conductivity is gradually decreased as the composition of amorphous silicon shell increases.In addition,by calculating the phonon density of state,we demonstrate that the reduction in thermal conductivity of the core/shell NW stems from the increase of the low frequency modes and the depression of high-frequency nonpropagating diffusion modes.These results provide an effective way to modify the properties of core/shell NWs for related application.