Quantitative Discrimination of Effective Porosity Using Digital Image Analysis - Implications for Porosity-Permeability Transforms
Five relevant digital image analysis parameters for fluid flow are obtained from 2-D image analysis of carbonate rocks: 2-D image porosity, amount of pores, pore shape, total perimeter per area and dominant pore size range. Micro-porosity leads to low permeable, highly porous rocks. 2-D image porosity represents the macro-porosity because the resolution subtracts the small pores from the porosity. Compared to the total porosity, it improves the prediction of permeability by an order of magnitude in the high porosity range. Pore shape factor γ reduces the uncertainty in permeability prediction to 2 orders of magnitude. Pore shape factor analysis is restricted to samples with more than 4000 pores/cm. CT scans of plugs reveals that the pore shape factor γ is a relatively constant measure of the pore shape (+/0.2) throughout the sample plug. The larger the average pore size, the higher the velocity at a given porosity. The average pore size can be quantified by the upper limit of the dominant pore size range.
Quantitative Characterization of Carbonate Pore Systems by Digital Image Analysis
A new method of digital image analysis can quantify pore parameters over more than three orders of magnitude, from a submicron to a millimeter scale. This porosity characterization does not require knowledge of lithology, age, burial depth, or diagenesis of the sample. The method is based on digital analyses of images from thin sections at variable magnifications taken under an optical microscope (OM) and under an environmental scanning electron microscope (ESEM). The results help explain variations in permeability for carbonate samples with a variety of complex pore structures. The analyses, however, can be done on any thin sections of other rock types. The OM images provide macroporosity information, whereas the ESEM images yield information on microporosity. The boundary between macroporosity and microporosity is defined at a pore area of 500 µm2, which translates to a pore length of approximately 20 µm, which is roughly the thickness of a thin section and thus the resolution of the OM. The digitized thin-section images are binarized into a macropore and a matrix phase (OM) or a micropore and a solid phase (ESEM). A standard digital image analysis program is used to detect all individual pores and to measure pore area and pore perimeter. Based on these analyses, one can calculate for each sample the amount of macroporosity, the amount of microporosity within the matrix (intrinsic microporosity), the shapes of the macropores (perimeter over area), and the pore size distribution. Comparison of total porosity determined from plugs indicates that macroporosity and microporosity values based on this methodology match the plug data, confirming the validity of the method. The combination of macroporosity and microporosity data yields pore size distribution and pore shape information that can explain the distribution of physical properties, in particular permeability. In parameter sensitivity analyses using neural networks, permeability appears to be mainly controlled by the macropore shape in high-permeability samples, and by the amount of intrinsic microporosity in the low-permeability samples.
Enhancement of surface properties on Low Density Polyethylene packaging films using various fluorination routes
Nowadays, packaging market deployment requires an important attention. Influence of treatment with molecular (F2) or atomic (Fradical dot) fluorine on properties of Low Density Polyethylene (LDPE) films was investigated. The films were treated using direct fluorination conditions with F2 or a specific reagent XeF2, which releases atomic fluorine Fradical dot. Changes of LDPE chemical composition were investigated by FTIR and solid state NMR. Surface morphology was studied by several microscopy techniques (SEM and AFM). Finally to further characterize film properties after treatments, surface energy measurements and electron paramagnetic resonance (EPR) analyses were also carried out. An upper fluorinated layer, which contains mainly high amount of single bondCF2single bond, was formed during the direct fluorination conditions (F2). For the process performed with XeF2, specific groups single bondCHFsingle bond were detected not only on the polymer surface but also in the bulk. The final CHF/CF2 ratio depended on the fluorination route. Treatment with Fradical dot (originated from XeF2 decomposition) resulted in single bondCHFsingle bond groups in bulk prevailing formation whereas F2 formed mainly single bondCF2single bond groups. Regardless to the reactive species, radicals (dangling bonds) appeared during the fluorination and reacted with oxygen during the exposition to air after the treatment. Such a process resulted in oxygenated polar groups formation and consequently in the surface energy increase.