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Kurdian A.R.,Islamic Azad University at Urmia | Kurdian A.R.,Sahand University of Technology | Kurdian A.R.,Iranian Central Oil Fields Company | Bahreini M.,Iranian Central Oil Fields Company | And 2 more authors.
Desalination | Year: 2013

Membrane distillation (MD) can be used to process highly concentrated aqueous solutions to recover water. In this study we tried to model direct contact membrane distillation process in three different temperature systems using mass and energy balance. Data used in this study were the water flux behavior using two aqueous salt solutions of sodium sulfate (Na2SO4) and sodium chloride (NaCl) which were extracted from C.M. Tun et.al in a MD set up. Membrane flux behavior and other model parameters for a GVHP hydrophobic membrane were calculated. Initial concentration of sodium sulfate and sodium chloride was 2. M and 4.5. M, respectively, which was tested in three temperature systems of feed/permeate, 60/20, 60/30 and 50/30. It was found that both concentration and temperature polarization influenced the performance of MD. Mean relative absolute error for systems 60/20, 60/30 and 50/30 was 7.29%, 7.52% and 8.75% for sodium sulfate and 4.34%, 10.99% and 5.01% for sodium chloride, respectively. © 2013 Elsevier B.V.

Amiri M.,University of Technology Malaysia | Ghiasi-Freez J.,Iranian Central Oil Fields Company | Golkar B.,Petroleum University of Technology of Iran | Hatampourd A.,Shahid Bahonar University of Kerman
Journal of Petroleum Science and Engineering | Year: 2015

Tight reservoir refers to reservoirs with low porosity and permeability. Estimating Petrophysical parameters of Tight Gas Sand (TGS) reservoirs is one of the most difficult tasks in reservoir characterization studies. These reservoirs usually produce from multiple layers with different and complex properties. Water saturation is an important petrophysical property representing the fraction of pore volume occupied by formation water that needs to be determined accurately when attempting to characterize hydrocarbon reservoirs. The exact determination of water saturation leads to a precise evaluation of initial hydrocarbon in place, which in turn provides valuable insight into future oil field development plans. In this paper, a model based on feed-forward - back propagation error Artificial Neural Network (ANN) optimized by Imperialist Competitive Algorithm (ICA) to predict water saturation in TGS reservoirs is proposed. ICA is employed to obtain the optimal contribution of ANN for a better water saturation prediction. Conventional well log data are used as input and water saturation data measured on core samples as output variables to the ANN model. In the current study, a number of 2200 data taken from 12 wells selected from a number of TGS basins are used to build a database. The performance of the proposed ICA-ANN model has been compared with the conventional petrophysical and ANN models. Based on cross validation measures, the results clearly show that the ICA-ANN model has outperformed the conventional methods in terms of effectiveness, robustness and compatibility. © 2015 Elsevier B.V.

Nasriani H.R.,Iranian Central Oil Fields Company | Kalantariasl A.,University of Adelaide
Society of Petroleum Engineers - SPE Asia Pacific Oil and Gas Conference and Exhibition 2011 | Year: 2011

Multiphase flow occurs in almost all producing oil and gas/condensate wells. Wellhead chokes are special equipment that widely used in the petroleum industry to control flow rate, to maintain well allowable, to protect surface equipments, to prevent water and gas coning and to provide the necessary backpressure to reservoir to avoid formation damage from excessive drawdown. Accurate modeling of choke performance and selection of optimum choke size is vitally important for a petroleum engineer in production from reservoirs due to high sensitivity of oil and gas production to choke size. Two main approaches have been proposed for prediction of multiphase flow through chokes can be classified as either analytical or empirical and majority of correlations were developed for critical flow conditions. Although most of the correlations available to petroleum engineers are for critical flow but in lots of high rate gas/condensate wells subcritical flow occurs in large choke sizes.There is no empirical correlation for wellhead choke performance under subcritical condition for high rate gas condensate wells, especially in large choke sizes. The first aim of this paper is to develop a new simple empirical Gilbert type correlation for high rate gas condensate wells under subcritical flow in large choke sizes (40/64 in. to 192/64 in.) using non-linear regression analysis based on 61 field data points of 15 wells from ten different fields. The second is to extend the work of Al-Attar for high rate gas condensate wells flowing through large choke size under subcritical flow conditions and check the applicability and advantages. Finally, statistical comparison between these two approaches is done with different error parameters. Copyright 2011. Society of Petroleum Engineers.

Behrouzifar A.,Iran University of Science and Technology | Asadi A.A.,Iran University of Science and Technology | Mohammadi T.,Iran University of Science and Technology | Pak A.,Iranian Central Oil Fields Company
Ceramics International | Year: 2012

Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3-δ (BSCF) perovskite powder was synthesized via EDTA/citrate complexation method. BSCF membranes were formed by pressing powder at 400 MPa and sintering at 1100°C for 10 h. XRD patterns showed that a high pure powder with cubic structure was obtained. SEM micrographs revealed that the membranes are dense with large grains. Effects of temperature, feed and permeate side oxygen partial pressures, flow rates and membrane thickness on oxygen permeation flux were studied experimentally. A Nernst-Planck based mathematical model, including surface exchange kinetics and bulk diffusion, was developed to predict oxygen permeation flux. Considering non-elementary surface reactions and introducing system hydrodynamics into the model resulted in an excellent agreement (RMSD = 0.0617, AAD = 0.0487 and R 2 = 0.985) between predicted and measured fluxes. The results showed that oxygen permeation flux increases with temperature, feed side oxygen partial pressure and flow rates, however decreases with permeate side oxygen partial pressure and membrane thickness. Contribution of feed side surface exchange reactions, bulk diffusion and permeate side surface exchange reactions resistances in the total resistance are in the range of 8-32%, 10-81% and 11-59%, respectively. Permeation rate-limiting step was determined using the membrane dimensionless characteristic thickness. © 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Rahmani Y.,National Iranian Oil Company | Rahmani Y.,Iranian Central Oil Fields Company | Ganji D.D.,Babol Noshirvani University of Technology
Journal of Thermophysics and Heat Transfer | Year: 2014

The phenomenon of the Newtonian and non-Newtonian fluid flows in ring-shaped pipe has been assessed by the homotopy perturbation method (HPM). An incompressible flow in a ring-shaped pipe by a powerlaw model known as a non-Newtonian fluid was assumed. A direct numerical solution (the fourth-order Runge-Kutta) is implemented to show the preciseness of the results. The effects of the pressure gradient, material parameters, and Brinkman number on the velocity and temperature profiles were investigated and graphically presented. A comparison between analytical and numerical solutions was made. The results show that the velocity increases as the pressure gradient decreases. Moreover, the temperature also increases as the pressure gradient decreases.

Bagheri M.,Islamic Azad University at Tehran | Gandomi A.H.,Islamic Azad University at Tehran | Shahbaznezhad M.,Iranian Central Oil Fields Company
Expert Systems | Year: 2013

There has been considerable interest in predicting the properties of nitro-energetic materials to improve their performance. Not to mention insightful physical knowledge, computational-aided molecular studies can expedite the synthesis of novel energetic materials through cost reduction labours and risky experimental tests. In this paper, quantitative structure-property relationship based on multi-expression programming employed to correlate the formation enthalpies of frequently used nitro-energetic materials with their molecular properties. The simple yet accurate obtained model is able to correlate the formation enthalpies of nitro-energetic materials to their molecular structure with the accuracy comparable to experimental precision. © 2012 Wiley Publishing Ltd.

Abootalebi O.,Iranian Central Oil Fields Company | Kermanpur A.,Isfahan University of Technology | Shishesaz M.R.,Petroleum University of Technology of Iran | Golozar M.A.,Isfahan University of Technology
Corrosion Science | Year: 2010

In this paper, a sacrificial anode cathodic protection problem of 2D steel storage tank was simulated using boundary element method. The tank was protected by a zinc anode located directly on structure wall. Data obtained from potentiodynamic measurements were used as boundary condition. In this study, optimum location of the anode was determined, and the influence of anode length and paint defect on the level of protection provided by system were investigated. This study showed that boundary element method is beneficial in modeling and analyzing cathodic protection systems and calculated results were consistent with expectations from the basic corrosion concepts. © 2009 Elsevier Ltd. All rights reserved.

Hatampour A.,Pars Oil And Gas Company | Ghiasi-Freez J.,Iranian Central Oil Fields Company
Petroleum Science and Technology | Year: 2013

Sonic wave velocities, including compressional, shear, and Stoneley, are functional and practical parameters for various branches of reservoir characterization. In the last few years, several tools such as the dipole shear sonic imager (DSI) were introduced for measuring sonic wave velocities. Most of these instruments are expensive and drilling companies do not run them in all wells of a field because of economical restrictions. In this study, an accurate, intelligent, and indirect method was presented for prediction of sonic wave velocities, which are directly obtained from dipole shear sonic log, utilizing conventional well log data and fuzzy logic technique. Furthermore, the proposed methodology was applied on a carbonate reservoir of Iran. The results of the case study demonstrated the capabilities of fuzzy logic for estimation of sonic wave velocities, where DSI may not be run. The MSEs of the predicted Vp, Vs, and Vst in the test data calculated 1.47 (US/F), 4.96 (US/F), and 2.219 (US/F), respectively, which correspond to the R 2 values of 91.8%, 89.3%, and 90.4%, respectively. © 2013 Copyright Taylor and Francis Group, LLC.

Dehghan M.,Semnan University | Rahmani Y.,Babol Noshirvani University of Technology | Rahmani Y.,Iranian Central Oil Fields Company | Domiri Ganji D.,Babol Noshirvani University of Technology | And 3 more authors.
Renewable Energy | Year: 2015

The case of combined conduction-convection-radiation heat transfer usually occurred in solar thermal usages is the aim of the present study. This type of combined heat transfer in heat exchangers filled with a fluid saturated cellular porous medium is investigated. The flow is modeled by the Darcy-Brinkman equation. The steady state model of this combined heat transfer is solved semi-analytically based on the homotopy perturbation method (HPM) and numerically based on the finite difference method. No analytical solution has been previously proposed for the problem. Effects of porous medium shape parameter (s) and radiation parameters (Tr and λ) on the thermal performance are analyzed. Furthermore, a discussion on the accuracy and limitations of the HPM in this kind of problems is represented. This study shows that semi-analytical methods (like HPM, VIM, DTM, and HAM) can be used in simulation and prediction of thermal performance of solar energy harvesting systems. © 2014 Elsevier Ltd.

Asl H.M.,Iranian Central Oil Fields Company | Vatani A.,University of Tehran
International Journal of Pressure Vessels and Piping | Year: 2013

The purpose of this study is to develop an appropriate numerical model to predict the onset of the failure of a pipeline-wall during an in-service welding process. Therefore, the thermo-mechanical stresses as well as the temperature across the pipe wall have been obtained and the former have been compared against the temperature-dependent yield stress of the material. The results show that this is a more accurate criterion in order to check the burn-through risk and when the effective stress at two thirds of the pipe wall thickness is larger than the yield stress at the associated temperature, there is a risk of burn-through. The results show that burn-through may occur under the welding pool, and it is more likely to happen in the primary passes of the welding. •To evaluate the risk of burn-through, the critical level of 980 °C is not only sufficient.•We find that the mechanical stresses also play a major role in the burn-through.•The effective stress should be compared against the temperature-dependent yield stress.•The geometry of welding passes has a major role in the occurrence of burn-through.•The risk of burn-through is high during the first pass than the second pass. © 2013.

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