Pressure drawdown equations for multiple-well systems in circular-cylindrical reservoirs

Jing Lu, Tao Zhu, Anh Dinh, Djebbar Tiab and Freddy H. Escobar

Currently, in the oil industry, a field usually contains several wells producing from the same drainage domain, and each well will have an effect on the pressure at other wells. For an infinite-acting multiple-wells system, pressure drawdown equation is already obtained by using superposition principle. This paper presents pressure drawdown equations of a multiple-wells system in a circular cylindrical reservoir with constant pressure outer boundary. The proposed equations provide fast analytical tools to evaluate the performance of multiple wells, which are located arbitrarily in a circular cylinder reservoir, and are producing at different rates. Here, it is also examined the pressure drawdown response of a specific well located in a system of producing wells. The interference effects of nearby producing wells on the pressure drawdown response are investigated. The proposed equations are illustrated by numerical examples. It is concluded that, for a given multiple-wells system in a circular cylindrical reservoir, well pattern, well spacing, skin factor, flow rates and well off-center distances have significant effects on single well pressure drawdown behavior. Because the reservoir is under edge water drive, the outer boundary is at constant pressure, when producing time is sufficiently long; steady-state is definitely reached.

Prediction of cross polarization discrimination at millimeter wave band due to dust storms

Abdulwaheed Musa and S. O. Bashir

Microwave links performance during dust storms has received considerable interest in recent time with emphasis on signal attenuation. However, phase shift and cross polarization have not been tackled enough. This paper investigates cross polarization discrimination (XPD) induced by dust storms at millimetre wave band. It introduces simple models of the wave propagation through dust storms. The models are developed based on the forward scattering amplitude of particles using Rayleigh method. Three conditions are set to validate the suitability of the Rayleigh approximation for the model. It is shown that the method is valid for determining the scattering of ellipsoidal dust particles for the particle sizes and frequency range considered. The scattering coefficients are derived and mathematical models for phase shift and attenuation are proposed in terms of relative permittivity and visibility. Results of the proposed model compared with some published results show close agreement. Differential phase shift and attenuation are computed and XPD introduced by dust storms in such links are predicted using the model parameters as inputs. Attenuation in dry dust is only significant when the visibility becomes severe. XPD at such visibility also becomes significant i.e. numerically low. A similar trend is found as the frequency increases.

Adaptive neuro-fuzzy inference systems (anfis) modeling of reactive distillation process

Abdulwahab Giwa, Saidat Olanipekun Giwa and Hale Hapoglu

This work has been carried out to develop ANFIS models for the reactive distillation process used for the production of isopropyl alcohol from the hydration reaction of propylene. The data used for the development of the models were generated from the Aspen HYSYS system of the process that comprised two feed streams - the upper feed stream from where the less volatile feed, water, was fed and the lower feed stream from where the more volatile feed, propylene, was fed into the column. The hydration reaction of the process was a reversible type occurring in liquid phase in the reaction sections of the column. The ANFIS models were trained, tested and simulated with the aid of MATLAB. The inputs of the models were the reflux ratio and the reboiler duty while the outputs were the top segment and the bottom segment temperatures. The high fit values and the low means of absolute errors obtained respectively from the training and the testing of the ANFIS models developed for the top segment and the bottom segment of the reactive distillation column used for the production of isopropyl alcohol have revealed that the developed ANFIS models represented the reactive distillation process in a very good manner.

This article commences with a definition of slow increasing function and moves on to delineate a few properties of slow increasing functions. Besides, several applications in some problems of number theory using the theory of slow increasing functions are also presented to show how useful these functions prove in solving complex problems.

Abstract:

This paper presents the design and simulation for maximum power point tracking (MPPT) for photovoltaic system, which includes a high-efficiency dc-dc boost converter with a modified incremental conductance algorithm. The converter can draw maximum power from the PV panel for a given solar insolation and temperature by adjusting the duty cycle of the converter. The modelling procedure for the circuit model was presented using MATLAB/Simulink Sim-power. The MPPT system has been tested with solar panel ICO-SPC 100 W module under various operating conditions. The obtained results prove that the proposed MPPT can track even under sudden change in sunlight conditions and loading level.

Use of CFD to model emergent vegetation in detention ponds

Alexandros Tsavdaris, Steve Mitchell and John B. Williams

Abstract:

This paper investigates the accuracy, applicability, and suitability of two different numerical modelling approaches available in Ansys Fluent 12.1 for the study of flow in detention ponds with emergent vegetation by making use of experimental results obtained in a laboratory flume. The aim of this investigation is to formulate an automated first-order approximation technique that could be used as part of an urban drainage model; such an approach could be an accurate yet practical technique for modelling the effects of vegetation in ponds at pre-construction stage in the interests of predicting general flow patterns. Using the actual vegetation density of a surface water detention pond located at Waterlooville, Hampshire, UK, replicated in a laboratory flume, two different Computational Fluid Dynamics modelling strategies were tested. The first involved the specification of the individual stems within the computational domain, and these results showed very good agreement with experimental data. In the second approach, a porous zone condition was applied in the vegetated region, and here the results seem to be appropriate for predicting general flow arrangements, though without being hydro-dynamically as accurate as the first approach.

With the advancement in low power system technology, energy harvesting systems have become a research hotspot over the last decade. The main advantage of the system is that they require minimum maintenance which makes them to be deployed in large scale or previously inaccessible locations. Therefore, the target of energy harvesting is to power autonomous electronic systems over their lifetime. Mechanical energy is the most ubiquitous and accessible energy source in the surroundings. Harvesting this type of energy exhibits a great potential for remote wireless sensing devices, charging batteries, and powering electronic devices. In this paper, we reviewed self-powered, self-sensing devices which describe different ways of mechanical energy harvesting. Comparison of mechanical energy harvesting devices in terms of their power output and frequency were presented. Self-powered system offers great potential for solving difficult problem of supplying energy.

Processing dependent flexural strength variation of jute fiber reinforced epoxy composites

Abstract:

Environmental awareness of human society towards materials usage has attracted attention of many researchers in the natural fiber reinforced polymer composite because of its specific mechanical properties and biodegradability. However, in many cases, composite properties are dependent on its manufacturing routes. In this research work, various conventional composite processing routes (hand-lay-up, vacuum assisted resin infiltration; VARI and compression molding) were chosen for manufacturing 35% volume fraction of jute fiber epoxy composite. The developed composites were characterized by three point bending test according to ASTM D 790 standard and the fracture surfaces analysis under FEG SEM. The transverse three point bend properties were experimentally analyzed with fiber center to center distance (strain magnification) model. The observed experimental results revealed the maximum flexural strength for the compression molded composite and the minimum for that of hand-lay-up process. The mechanical properties were also explained in terms of fractographs obtained from SEM observation.

Enhanced approaches to improve graphical user interface testing process

Vijayakumar. E and M. Punithavalli

Abstract:

Graphical User Interfaces (GUI) is important components of Event-Driven Software that are used mainly for improving user-computer interactions. As the number of graphical controls that the user can select using mouse or key board is very high, the number of test cases generated is also very high. Thus, the test cases generation process has to be optimized. This paper performs this in three steps by enhancing the three operations, namely, test case generation, test case reduction and test case prioritization. Experimental results prove that the methods proposed have optimized the process of test case generation and has improved the accuracy of error detection rate. A maximum of 99.25% fault detection rate was obtained which shows that the proposed amalgamation of techniques are successful and can be used by the 21st century software.

Abstract:

A study was conducted to determine the distribution of forms of K (water soluble K, exchangeable K, non exchangeable K, and total K) of potassium in some Ghanaian soils occurring along toposequence using standard laboratory procedures. The soils were the Edina, Atabadzi, Benya, Udu and Kakum series (Acrisols), which form the Edina catena. The concentrations of total K in the soils ranged from 0.64 to 2.37 (cmol (+) kg^-1) with Kakum series showing the lowest (P < 0.05) value. Water soluble K and exchangeable K concentrations in the soils ranged from 0.05 to 0.25 c mol (+) kg^-1, and 0.26 to 0.89 cmol (+) kg^-1, respectively, with the Kakum series again showing the lowest values (P < 0.05) for both K forms. The Edina series, occurring at the summit of the catena, showed the highest concentrations of both water soluble and exchangeable K. In the study non-exchangeable K concentrations measured in the soils varied between 0.20 and 1.25 cmol (+) kg^-1. The study showed that exchangeable K constituted the highest proportion of the total K measured in the soils, while the proportion of water soluble K in the total K measured was the lowest. Pooling all the data obtained in the study, water soluble K and exchangeable K concentrations positively correlated with organic matter, cation exchange capacity and percentage bas saturation.

Optimization of wireless optical communication system with placement of relay using shuffled frog leaping algorithm

A. Jabeena, T. Jayabarathi, Palak Gupta, Geetashree Hazarika and Nibedan Bhawsinka

Abstract:

Wireless Optical communication (WOC) is improved using relay assisted transmission which exploits multiple shorter hops that gives a better performance gain. Relay assisted transmission is utilized as a mitigation tool in combating atmospheric turbulence occurring in the communication channels. The main aim is to minimize the outage probability and optimize relay locations for parallel and serial FSO relaying. In this paper we address the major limiting factor for links measuring more than a kilometer; the error rate performances is dismal and therefore relay assisted transmission is employed to combat this shortcoming. The focus of this study is on considering the channel model, which takes into account both path-loss and turbulence-induced fading. The locations of the relay are found out using different algorithms and then compared to find out the best optimized result.

Determination of ungauged catchment losses rate, catchment wetness index and baseflow

Yuk Feng Huang and Teang Shui Lee

A single-event distributed model simulating inflow into the ungauged Batu Dam at Kuala Lumpur was formulated. This model is a one-dimensional finite element method that follows the procedure presented by Ross in [1]. With excess rainfall as input, the rainfall runoff simulation sub-model (as one of the sub-models in the developed Batu Reservoir Inflow Forecasting Model) was developed based on the one dimensional Saint-Venant equations with kinematic wave approximation and solved using the finite element standard Galerkin’s residual method, and incorporating Manning’s equation. The spurious oscillatory behaviour of the standard Galerkin’s residual method can be suppressed by using a one minute time increment taking into cognizance the requirement of the Courant condition. The catchment losses rate concept developed in this study was dependent on catchment antecedent soil moisture conditions (catchment wetness index) and weighted average rainfall intensity. A catchment wetness index was formulated empirically based on the net total rainfall volume retained in the catchment accumulated over a five-day period prior to the simulated event (following the 5-day Antecedent Precipitation Index API5 concept). An empirical equation for computating baseflow volume for reservoir water level increment simulation was developed based on the five previous-days approach. The Catchment Losses Rate-Catchment Wetness Index-Weighted Average Rainfall Intensity (LWRI) curves were proposed for the study area, and seven curves were derived after model parameter calibration. Manning’s coefficients used in model parameter calibration were also confirmed to be 0.400 and 0.040 for overland and channels respectively. The model was verified to simulate the reservoir water level increment accurately. This is shown by the very strong 0.9799 correlation coefficient, relatively small mean of absolute water level error that does not exceed 2.20 cm at 95% level of confidence from the single mean t-test, no significant differences in the means and variances from the paired t-test and the F-distribution variance ratio test respectively, and Theil’s coefficient of 0.062 obtained.

Photophysical studies of spin-cast polymer films

Subhi Kemal Hassan, Batool Daram Bellawa and Sahar Issa Al-ASafi

Abstract:

Previous research on spin cast films has centered on macroscopic variables such as film thickness and uniformity. Our work has focused on the microscopic properties of polymer chains that compose these films, using materials and processing conditions that are similar to those used in lithographic applications. We believe the process of spin casting causes the polymer chains to exist in oriented, non-equilibrium chain conformations. Orientation of the polymer chains will increase the Trans conformational segments as found by Jasse and Koenig (20), which slightly increases the concentration of intramolecular EFS. However, this increase is insufficient to account for the observed 200% increase in Ie/Im caused by the spinning process. An increase in Intermolecular EFS and/or the rate of energy migration must be included. After long annealing times near the Tg the short chain stress can be relaxed by secondary relaxation phenomena, as measured by le/Im value. Long chain stress, however, still remains in the film. Consequently, significant residual stress may still remain in resist films after the prebaking process commonly used in the industry. The pin cast films of novolac polymers in solution with a small molecule dye indicate that aggregation may occur for pyrene concentrations as law as 6 mol %. This is well below the concentration of sensitizer in many commercially used positive resist systems, indicating that the resist films may be inhomogenaous.

Abstract:

The effects of temperature and pyrolysis time on the properties of polyethylene wax and gaseous products produced from waste polyethylene water sachets were investigated. Waste polyethylene water sachets were pyrolysed at temperatures between 110oC and 150oC and different time. The effect of temperature and pyrolysis time is significant on the yield, melting point and penetration degree of polyethylene wax produced. The polyethylene wax obtained has a penetration degree of 1-40.6 mm; the melting point was 76 ^oC - 142 ^oC while the yield of polyethylene wax obtained was 95.31-50.44 %. Waste sachets pyrolysed at 130-150˚C for 30-40 minutes produce high quality polyethylene wax (paraffin and microcrystalline wax) from waste polyethylene water sachets with yield of above 75%, good melting point and penetration degree that meet industrial standard The remaining non condensable hydrocarbon gases produced along with the wax, which is mostly ethane, propane, propylene can be used as feedstock for the heater or sold as fuel gas.

Fuzzy logic based optimum penstock design: elastic water column theory approach

Priyabrata Adhikary, Pankaj Kumar Roy and Asis Mazumdar

Abstract:

Shock wave or surge events are disturbances in the water caused during a change in state, typically from one steady or equilibrium condition to another. The principle components of the disturbances are head pressure and flow changes at a point that causes propagation of pressure waves throughout the distribution system. The larger the magnitude of the velocity change and the larger the magnitude of the wave speed, the greater the change in head-pressure will be. Many factors related to small hydro power (SHP) water conveyance system or penstock design are subjective and difficult to quantify. Hence fuzzy logic can be one of the most powerful design decision making method of shock wave or shock wave or surge analysis of penstock. To the best of the authors knowledge this novel Fuzzy Logic approach of optimum water conveyance system or penstock designing by shock wave analysis for small hydro power generation is absent in renewable energy or fluid mechanics literatures due to its assessment complexity.

CFD simulation of a single phase flow in a pipe separator using reynolds stress method

Eyitayo A. Afolabi and J.G.M Lee

Abstract:

The Reynolds stress method of commercial ANSYS FLUENT software is used for the numerical simulation of the single phase flow in a 30mm ID pipe separator. The CFD predicted results is then compared with the stereoscopic PIV measurements at the three different axial positions. The comparison between the experimental and computational results showed good qualitative agreement at most axial positions within the pipe separator and considerable insight was gained into the flow mechanism. However, there were some discrepancies between the CFD results and the SPIV measurements at some axial positions away from the inlet section. Therefore, Reynolds stress model (RSM) is deemed to be a good methodology for modelling the hydrodynamic behaviour in a pipe separator system.