Determination of Archie’s Tortuosity Factor from Stoneley Waves in Carbonate Reservoirs

One of the fundamental equations in calculate the saturation of fluid in hydrocarbon reservoirs is the Archie’s equation. In addition to the parameters measured by well logging such as porosity and resistivity, there are others parameters that called Archie’s coefficients. Archie provides constant values for this coefficient base on experimental core’s data, accordance with saturation formula in sandstone. In carbonate reservoirs nevertheless the sandstone reservoirs, high heterogeneity, variety in lithology and texture, shape and distribution of pores, due to this coefficient is not constant. So, variation of tortuosity as a coefficient that depends on the way correlation between pores, is high and considering a constant value due to error in calculation of fluid saturation. In this study, with the stoneley waves measured from DSI tools and required calculation, the value of tortuosity coefficient calculated continuously in well no.10 Darkhovin field. The regression of calculated values with the core data is 83.16 percent, that showed this method is useable for calculation the tortuosity.

Diffusivity of solvents in semi-crystalline polyethylene using the Vrentas-Duda free-volume theory

Diffusion of penetrants in polyethylene below the melt temperature is heavily dependent on the crystallinity of the polyethylene, the temperature of the experiment, and the concentration of solvent in the polymer. As the crystallinity of the polyethylene increases, there is an increase in the path that the solvent must travel as the solvent cannot penetrate the tightly packed chains in the crystalline domain. This effect is typically accounted for by a tortuosity factor. In this work, a simple and effective characterization of the tortuosity factor based simply on the crystal weight fraction has been developed. Data have been collected for six polyethylenes having densities ranging from 0.912 to 0.961 g/cm3 and for three solvents – isopentane, cyclohexane, and 1-hexene. Diffusivity predictions have been obtained using the free-volume theory of Vrentas and Duda in conjunction with the new tortuosity factor. The polyethylenes had crystallinities varying from 40% to 82% effecting an approximately 60% change in the diffusivity. The decrease resulting from ignoring the crystallinity altogether was in some cases essentially a factor of 5. The error in the predicted diffusivities over all the systems was 25%. For cyclohexane, it is shown that the same model parameters characterize data below the melt temperature (in the semi-crystalline region) as well as above the melt temperature (in the amorphous region).

Sobre la relación entre las distribuciones de los tamaños de poros y partículas del suelo

The particle and void sizes distributions of the soil are related with the assumption that a voidconstant relationship at all di§erent scales and a relationship between pore and particle size ofa given packing. In the relationship between pore and particle sizes, a particle elongation factoris applied based on the Arya and Paris model. A áow trajectory tortuosity factor based on theFuentes model can also be applied. Since the void size distribution is associated to the soil waterretention curve, the proposed relationship can be used to estimate this curve from particle sizedistribution.

Tortuosity and mass transfer limitations in industrial hydrotreating catalysts: effect of particle shape and size distribution

Comparison of the tortuosity factor of γ-alumina supports and hydrotreating catalysts evaluated with PFG-NMR, inverse liquid chromatography and catalytic experiments.