جستجوی مقالات مرتبط با کلیدواژه "محیط متخلخل" در نشریات گروه "زمین شناسی"

Herein results obtained from a laboratory study of MTBE transport through a vertical layer of an unsaturated soil are reported. MTBE with a concentration of 200 mg/l was released on the top of the experimental model. The concentration of the pollutant was measured in time in different points using gas chromatography. Results indicated that, the vertical movement of the pollutant was more than the horizontal one. For instance, the MTBE concentration was 135 mg/l in a vertical distance of 5 cm, 10 minutes after the start of experiment and it was increased to 188 mg/l, after 133 minutes. For a point with 15 cm of vertical distance, after 25 minutes the concentration of MTBE was 120 mg/l and it increased to 185 mg/L after 133 minutes. Also for a point located in a vertical distance of 30 cm, after 100 minutes the concentration of MTBE measured equal to 127 mg/l and at the end of the experiment it increased to 148 mg/l. In conclusion it can be said that after 10 to 25 minutes after the adsorption capacity of the soil rechead its maximum and the movement of the pollutant began. With the beginning of the contaminant movement in the horizontal and vertical directions, the concentration of the pollutant increased and in the vertical direction this increase was more than that in the vertical direction. In fact, the diffusion velocity in the vertical direction was more than its velocity in the horizontal direction. Therefore, MTBE was more moveable with water and less adsorbing with soil.

Porous media such as groundwater aquifers, oil and gas reservoirs have a large amount of heterogeneity. Modeling of flow and transport in such environments is based on a survey of the properties of porous media. In this paper, fractal permeability of porous media has been estimated using the Monte Carlo simulation. Using the results of previous studies and measurements on several sandstone samples, such as porosity, fractal dimension, fractal property and intrinsic permeability, using a Monte Carlo probabilistic model and a set of random numbers between 0 and 1 and pore diameter measurement, the sandstone permeability was determined. Finally the simulated and measured values of samples sandstone permeability were compared. Monte Carlo simulation results show that without any need for empirical coefficients, domain discretization with only a few laboratories measured parameters one can reasonably determine the fractal permeability of porous media. Measured and calculated permeability correlations are matched 83 percent.

Wave velocity and attenuation are among the most important attributes of stress waves that propagate through geomaterials. Utilizing these attributes, it is possible to acquire useful information about porous geomaterials such as soil and rock and also the fluids that saturate the pores of geomaterials. The key point in order to gain these informations is to establish an accurate link between field measurements of wave attributes and physical properties of geomaterials’ skeleton and pore fluid. The pore fluids and their inhomogeneous distribution fluid are among factors that affect wave velocity and attenuation to a considerable extent. Patchy saturation of pores which occurs on the scale larger than grians size but smaller than wavelength is one of the reasons that causes inhomogeneity in pore fluid distirbution. The influence of such inhomogeneity is studied in present paper. Two different attenuation mechanisms including relative movement of fluid with respect to solid phase and also attenuation caused by grain to grain contact are implemented to fully assess wave attenuation. It is observed that the former attenuation is more dominant at higher frequencies compared to the latter attenuation.