Experimental Study On Micro-characteristic Of Two Phase Flow Of CO₂and Brine In Porous Medium

The greenhouse effect of CO2has give rise to the world-wide climatic change. The climate change problem requires a very broad range of solutions across many technologies and sectors, each with its own inherent set of opportunities and challenges. One of the most promising concepts is Carbon dioxide capture and storage (CCS) in saline aquifers, which are estimated to have worldwide capacity up to103Gt CO2. Carbon dioxide capture and storage (CCS) in saline aquifers at pore scale and sub pore scale can help to improve our knowledge of two phase flow characteristics of CO2and brine in porous media. It have important research value.Recent development in high resolution X-ray computed tomography (X-ray CT) allows direct visualization of porous structure. This technique is widely used in petroleum engineering (Enhanced Oil Recovery) labs. In this research, we use X-ray CT scanner to observe structural property of porous media and two phase flow characteristics of CO2and brine in porous medium during the core flooding experiments.Firstly, we research the Image Specification of X-ray CT. By scanning samples of different density, we confirm the linear relationship between the gray value of the samples scanned by X-ray CT and the densities of the samples. It is the same with the relationship between the density and CT number of custom X-ray CT.We research the bone structure characteristics of porous medium by using X-ray CT. We get porosity, and particle size distribution of the porous media.We perform two phase flow experiments of CO2and brine in porous medium. By using X-ray CT, we observe the flow characteristic of CO2and brine. The distribution of CO2and the distribution of porosity have the same tendency. The viscosity of CO2is much lower than the viscosity of brine. CO2prefer to occupy the large pore leaving brine at low porosity regions. Besides, the porous media has strong hydrophilic, the smaller pore space will adsorb more brine than larger pore space because of capillary force. We observe the flow characteristic of CO2and brine by using X-ray CT. The experiment results of seepage channel of CO2and brine in porous media prove that:when the fraction flow of CO2and brine reach the steady state, there will form stable seepage channel of CO2and brine in porous medium. The effect of gravity on the distribution of CO2and brine is obvious. When decreasing the pore size, capillary force increase, the effect of capillary force on the distribution of CO2and brine is significant. The influence of gravity will decrease.