PORE PRESSURE MODELLING IN A COMPRESSIONAL SETTING: A CASE STUDY FROM ASSAM,NE INDIA

The petroleum‐bearing Assam oil province, NE India, has a complex tectonic history resulting from the Cenozoic collision of the Indian Plate with the Eurasian and Burma Plates. Well data show that there are significant variations in the magnitude and stratigraphic occurrence of overpressures across the foreland basin. In areas which have not been affected by thrust tectonics, analyses of pore pressures in Upper Miocene to Eocene and underlying sequences indicate that overpressures are caused by disequilibrium compaction. Pore pressures were observed to be 25.8–28 MPa over a depth interval of 2259–2382 m and 43–45 MPa between depths of 3820 m and 3994 m. In the adjacent Schuppen (fold‐thrust) belt, multiple overpressure regimes are recognised and disequilibrium compaction is the main cause of the overpressures in both the supra‐thrust and the sub‐thrust successions. Unloading due to uplift and erosion in the supra‐thrust section of the Schuppen belt was quantified using velocity data and the normal compaction trend for shales; net uplift was estimated to total 1000–1600 m with a standard deviation of 250–476 m. Overpressure development in supra‐thrust strata in the Schuppen belt suggests the possible effects of normal burial prior to tectonic deformation, as well as of compaction related to high horizontal stresses resulting from thrusting and associated fold development. Pore pressures in the supra‐thrust section, over a depth interval of 700–1400 m which corresponds to the Oligocene to Upper Miocene succession, were observed to range from 9.6 to 19.5 MPa. The top of the overpressured zone in sub‐thrust strata was observed in the Upper Eocene to Oligocene succession at a depth of 3700 m, in the argillaceous Barail Formation, with pore pressures ranging between 48 MPa and 54 MPa. Pore pressures were estimated using acoustic log data calibrated to measured pressures from Modular Dynamic and Drill Stem Test data. The modelled pore pressures closely correspond to the measured data, supporting the robustness of the model. The numerical parameters defined in this study may be used for future exploration in the region.     

A Study on Arc Instability Phenomena of an Axial Injection Cathode Plasma Torch

Axial injection in plasma gun through the cathode has clear benefit of longer particle residence time and optimum particle trajectory in the plume; however, accelerated wear of the cathode seem to be the major issue in this approach. This study investigates the arc instability phenomena in an axially injecting single cathode plasma torch design. Gun voltage measurements were used to evaluate the arc behavior. For comparison purpose, arc fluctuations with a standard solid cathode torch design under identical operating parameters have also been studied. A comparison of different internal hardware configurations is also done to understand and establish the important factors in the design of the axial injection and solid cathode systems. Further, this study presents the influence of plume elongation and accelerated gas velocities on the arc behavior in different configurations under low pressure environment.     

Characterization of metals and salts‐based thermal energy storage materials using energy balance method

Thermal energy storage technologies minimize the imbalance between energy production and demand. In this context, latent heat storage materials are of great importance as they have a higher density of energy storage as compared with the sensible heat storage materials. The present study involves the characterization of energy storage materials using an energy balance cooling curve analysis method. The method estimates the convective heat transfer coefficient in the solidification range to characterize the phase change materials for applications in energy storage. The method is more beneficial than the Computer Aided Cooling Curve analysis methods as it eliminates baseline calculations and the associated fitting errors. Metals (Sn) and salts (KNO₃ and NaNO ₃) were used in the present work. Phase change characteristics like the rate of cooling, liquidus and solidus temperatures, time for solidification, and enthalpy of phase change were estimated for both metals and salts. It was observed that the energy balance cooling curve analysis method worked very well for metals but not well suited for low conductivity salts. Salts could not be characterized since the thermal gradient existing within the salt sample was not considered in this method.     

Heat deposition in thick targets due to interaction of high energy protons and thermal hydraulics analysis

Heat deposition inside thick targets due to interaction of high energy protons (E_p ∼ GeV) has been estimated using an improved version of the Monte Carlo simulation code CASCADE.04.h. The results are compared with the available experimental data for thick targets of Be, Al, Fe, Cu, Pb and Bi at proton energies of 0.8 GeV, 1.0 GeV and 1.2 GeV. A more continuous heat deposition approach which has been adopted in CASCADE.04.h yields results which are in better agreement with the experimental data as compared to the ones from the earlier version of CASCADE.04. The results are also compared with the predictions of the FLUKA Monte Carlo code. Both CASCADE.04.h and FLUKA predictions are nearly similar for heavy targets and both agree with the experimental measurements. However, they do have differences in predictions for lighter targets where measurements also differ from the predictions. It is observed that the maximum heat loss in thick targets occurs at the beginning of the target due to increasing nuclear reaction contributions. This aspect is crucial in designing the window of a spallation neutron target employed in an accelerator driven sub-critical system (ADS) as this is the first material to be traversed by the proton beam and is subjected to the maximum temperature gradient. Optimization of the target-window parameters requires a careful estimation of heat deposition in the window region and this has been demonstrated through thermal hydraulic studies related to the design of a realistic lead bismuth eutectic (LBE) spallation neutron target for an ADS system.     

Chemically reactive solute transfer in a moving fluid over a moving surface

The distribution of a solute, undergoing a chemical reaction, between a moving surface and a moving stream is analyzed in this paper: uniform concentration at the boundary is assumed. The governing nonlinear partial differential equations are first transformed into nonlinear ordinary differential equations (ODEs) by a similarity transform, and then the ODEs are solved numerically by a shooting method. The obtained numerical results are compared with the known results in the literature in order to demonstrate the validity of the solutions. Furthermore, analytical results are provided for some parameter regimes. The effects of the governing parameters on the flow and chemical fields are examined. The numerical results indicate that dual solutions exist when the sheet and the free stream move in the opposite directions. These results are in agreement with Ishak et al. (Chem Eng J 148:63–67, 2009), where the results were obtained without chemical reaction. The concentration boundary layer thickness decreases with an increase in the Schmidt number and reaction rate parameter. Moreover, mass absorption at the plate is noted in the case of a constructive chemical reaction.     

Treatment of arsenic contaminated water in a laboratory scale up-flow bio-column reactor

The present paper describes the observations on the treatment of arsenic contaminated synthetic industrial effluent in a bio-column reactor. Ralstonia eutropha MTCC 2487 has been immobilized on the granular activated carbon (GAC) bed in the column reactor. The synthetic water sample containing As(T) (As(III):As(V)=1:1), Fe, Mn, Cu and Zn at the initial concentrations of 25, 10, 2, 5, 10 ppm, respectively, was used. Concentrations of all the elements have been found to be reduced below their permissible limits in the treated water. The significant effect of empty bed contact time (EBCT) and bed height on the arsenic removal was observed in the initial stage. However, after some time of operation (approximately 3-4 days) no such effect was observed. Removal of As(III) and As(V) was almost similar after approximately 2 days of operation. However, at the initial stage As(V) removal was slightly more than that of As(III). In absence of washing, after approximately 4-5 days of operation, the bio-column reactor was observed to act as a GAC column reactor based on physico-chemical adsorption. Like arsenic, the percent removals of Fe, Mn, Cu and Zn also attained minimum after approximately 1 day and increased significantly to the optimum value within 3-4 days of operation. Dissolved oxygen (DO) has been found to decrease along with the increasing bed height from the bottom. The pH of the solution in the reactor has increased slightly and oxidation-reduction potential (ORP) has decreased with the time of operation.     

Slip effects on boundary layer stagnation-point flow and heat transfer towards a shrinking sheet

In the present study, we analyze the effects of partial slip on steady boundary layer stagnation-point flow of an incompressible fluid and heat transfer towards a shrinking sheet. Similarity transformation technique is adopted to obtain the self-similar ordinary differential equations and then the self-similar equations are solved numerically using shooting method. This investigation explores the conditions of the non-existence, existence, uniqueness and duality of the solutions of self-similar equations numerically. Due to the increase of slip parameter (δ), the range of velocity ratio parameter (c/a) where the similarity solution exists, increases.     

Fuzzy modeling of fuel cell based on mutual information between variables

This paper discusses estimation analysis study of fuel cell using Kalman filter and modeling of the output variables using fuzzy technique based on Gastofan-Kessel (GK) clustering algorithm. The objective of fuzzy model is to represent the dynamics of output variable as a function of most relevant set of input variables. The choice between most relevant and non-redundant input variables is based on mutual information theory. The fuel cell stack system is considered to have important interacting modules. The analytical equations are used to generate data to develop fuzzy model which closely flows the variations of output variables. The dynamic characteristics are predicted taking into account the reactant pressures, their mass flow etc. The performance of identified fuzzy model is tested at different initial load conditions. An analysis of the results based on the computation of the relative errors and on graphical representations is discussed.