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Coal fly ash was used to synthesize X-type zeolite by alkali fusion followed by hydrothermal treatment. The synthesized zeolite was characterized using various techniques such as X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, BET method for surface area measurement etc. The synthesis conditions were optimized to obtain highly crystalline zeolite with maximum BET surface area. The maximum surface area of the product was found to be 383 m 2 /g with high purity. The crystallinity of the prepared zeolite was found to change with fusion temperature and a maximum value was obtained at 823 K. The cost of synthesized zeolite was estimated to be almost one-fifth of that of commercial 13X zeolite available in the market.

The rheological behavior of a polymer solution is very important for its application in enhanced oil recovery. An experimental study was conducted to examine the effects of salts, alkali, and surfactants on the rheological properties of partially hydrolyzed polyacrylamide (PHPAM) over a wide range of parameters. The experimental results show that addition of ionic species significantly reduces the polymer viscosity by reducing the hydrodynamic size of the polymer. The power-law model was used to describe the rheological properties of the solutions. The flow behavior index, n, of the samples was in the range from 0.232 to 0.275, while the consistency index, K, ranged from (1.45 to 5.76) Pa • s n . The variation of viscosity with temperature was also studied and found to satisfy the Arrhenius equation.

Foam and surface tension behaviors of different ionic/nonionic surfactant solutions along with their different combinations have been investigated. Among different surfactants, sodium dodecyl sulfate showed the highest foamability over other surfactants. Mixed surfactant systems were always found to have higher foamability than the individual surfactant. It was also noticeable that nonionic surfactants show good foamability when they combine with anionic and cationic surfactants. In the case of mixed surfactant systems, nonionic/cationic surfactant mixtures showed lower surface tension than nonionic/anionic surfactant mixture due to a synergistic effect.

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Alkaline flooding is a method of enhanced oil recovery, in which alkali reacts with acidic components in the crude oil to form surface-active substances. In the present study, the interaction between alkali and crude oil was studied by measuring their physicochemical properties. A Fourier transform infrared (FTIR) spectrum of the crude oil reveals the presence of carboxylic acid groups leading to in situ formation of surfactants, which in turn decreases the interfacial tension between oil and water and other petrophysical properties responsible for better oil recovery. The effectiveness of alkali on enhanced oil recovery was tested with three sets of flooding experiments performed in the sand-pack systems. Substantial additional recoveries (more than 15% of original oil in place) over conventional water flooding were obtained in the present investigation.

Oil-in-water emulsions are important in the petroleum industry as a displacing fluid for enhanced oil recovery (EOR). To investigate the efficiency of oil-water emulsions in EOR, experiments were performed to characterize the emulsions in terms of their physicochemical properties and size distribution of the dispersed oil droplet in water phase. In the present study commercially available gear oil was used to prepare oil-inwater emulsions. Flooding experiments were also carried out to evaluate the effectiveness of the emulsion as displacing fluid for enhanced oil recovery. Substantial additional recoveries (more than 20% of original oil in place) over conventional water flooding were obtained in the present investigation.

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