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.

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.

Interaction between water-soluble polymers and anionic surfactants has been studied by surface tension and conductivity measurements. Sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) were used as surfactant while polyacrylamide (PAA), commercial grade partially hydrolyzed polyacrylamide (PHPA), and xanthan gum were used as water-soluble polymers for the present study. The behavior of surfactant-polymer interaction was found to be dependent on both surfactant and polymer concentrations. After the critical aggregation concentration (CAC), interaction between the water-soluble polymer and surfactants was started and above the polymer saturation point (PSP) polymer was saturated by surfactant with no further change of surface tension and conductivity of the solution. It has also been found that alkali (NaOH) and salts (Na 2 CO 3 , NaCl) have significant influence on the polymer-surfactant interaction. 

A high intensity source of a single neutrino flavour with known spectrum is most desirable for precision measurements, the consensus direction for the future. The beta beam is an especially suitable option for this. We discuss the prospects of a very long baseline beta beam experiment with a magnetized iron calorimeter detector. In particular, with the source at CERN and the detector at the proposed India-based Neutrino Observatory (INO) the baseline is near the 'magic' value where the effect of the CP phase is small. We observe that this experiment will be well suited to determine the sign of m 2 3 − m 2 2 and will be capable of probing θ 13 down to about 1 • .

Motivated by the possibilities of b − τ or t − b − τ Yukawa unification in the supersymmetric Grand Unified Theories, we consider the dangerous directions of the supersymmetric potential for large values of tan β ( > ∼ 30), in two versions of the minimal supergravity model with and without common soft breaking scalar masses at the GUT scale, where the potential may become unbounded from below. We find that for the common trilinear coupling A 0 < ∼ 0 the requirement of b − τ unification in conjunction with the stability condition on the potential yields highly restrictive sparticle spectra with upper, and in many cases, lower bounds stronger than the available experimental lower bounds, on the soft SUSY breaking common scalar mass and the common gaugino mass. Over a significant region of the parameter space, the model becomes even more restrictive if the common sfermion soft mass is different from the soft mass for the Higgs sector. We also find that the bulk of this restricted parameter space can be probed at the LHC. In models with t − b − τ Yukawa unification, A 0 ≤ 0 is ruled out from potential constraints.

Chemical flooding methods are now getting importance in enhanced oil recovery to recover the trapped oil after conventional recovery. In the present study, a comprehensive study has been carried out on alkali, surfactant and polymer flooding. The chemicals with different compositions and combinations were used to recover the oil after conventional water flooding. It has been observed that increase in concentration of alkali, surfactant and polymer increases the additional recovery, but beyond a certain limit, the increase in recovery is only marginal. A series of flooding experiments using the combination of the above methods have been performed with additional recoveries more than 25 %. An analysis has been made on the relative cost of the different chemical slugs injected and the corresponding additional oil recovery. Based on the analysis, an optimum composition of the alkali-surfactant-polymer system has been recommended.

We study the neutrino mass hierarchy at the magnetized Iron CALorimeter (ICAL) detector at India-based Neutrino Observatory with atmospheric neutrino events generated by the Monte Carlo event generator Nuance. We judicially choose the observables so that the possible systematic uncertainties can be reduced. The resolution as a function of both energy and zenith angle simultaneously is obtained for neutrinos and anti-neutrinos separately from thousand years un-oscillated atmospheric neutrino events at ICAL to migrate number of events from neutrino energy and zenith angle bins to muon energy and zenith angle bins. The resonance ranges in terms of directly measurable quantities like muon energy and zenith angle are found using this resolution function at different input values of $\theta_{13}$. Then, the marginalized $\chi^2$s are studied for different input values of $\theta_{13}$ with its resonance ranges taking input data in muon energy and zenith angle bins. Finally, we find that the mass hierarchy can be explored up to a lower value of $\theta_{13}\approx 5^\circ$ with confidence level $>$ 95% in this set up.Comment: some clarifications added, version accepted in PLB, 12 pages, 34 figure