Iranian Journal of Oil and Gas Science and Technology

Abstract Cobalt oxide catalysts supported on oxidized multi-walled carbon nanotubes (MWCNT) for the low-temperature catalytic oxidation of carbon monoxide were prepared by an impregnation-ultrasound method. These catalysts were characterized by N₂ adsorption/desorption, TEM, XRD, Raman, and H₂-TPR methods. The XRD and Raman results indicated that the phase of the synthesized cobalt oxide was in the Co₃O₄ form. The effects of cobalt oxide loading and reaction temperature were studied on the catalytic oxidation conversion of carbon monoxide. The TEM image of the best catalyst (14 wt.% metal oxide loading) revealed a good dispersion of Co₃O₄ over the surface of the support with an average particle size of 11-16 nm. Under the reaction conditions of T= 200-250 °C, P=1 bar, CO = 600 ppm, O₂ = 5 vol.%, GHSV = 30,000 hr.^−1, and Co₃O₄= 14 wt.%, CO conversion was 91%.

Abstract Use of amine solutions for the removal of acid gases such as carbon dioxide (CO₂) and hydrogen sulfide (H₂S) from natural gas is the most common method, and, in this process, operational problems because of foaming are reported. Foaming can lead to the entrainment of liquid into downstream process equipment and might result in a situation in which the process specifications cannot be met for acid gases. Alkanolamines in general have a negative effect on downstream process equipment, and the loss of amines has a negative effect on the health, safety, and environment (HSE). The foam reducing agents are often used to reduce the risk of heavy foaming in amine plants. This study concerns with foaming in amine-based CO₂ plants. To investigate foaming related to CO₂ removal from natural gas by amine solutions, the fundamental theory of foaming in gas-liquid contactors was first reviewed. Then, experimental techniques related to this phenomenon in diethanolamine (DEA)/CO₂ absorbers were considered. After that, foaming of diethanolamine solution polluted with different impurities was noticed, and the tendency of foam was measured by considering their foaming indices. To analyze the experimental measurements and experimental observations, a mathematical model was developed too. The model could justify the experimental measurement reasonably.

Abstract Abstract
In this study, a mathematical model is proposed for CO₂ separation from N₂/CO₂ mixtureusing a hollow fiber membrane contactor by various absorbents. The contactor assumed as non-wetted membrane; radial and axial diffusions were also considered in the model development. The governing equations of the model are solved via the finite element method (FEM). To ensure the accuracy of the developed model, the simulation results were validated using the reported experimental data for potassium glycinate (PG), monoethanol amine (MEA), and methyldiethanol amine (MDEA). The results of the proposed model indicated that PG absorbent has the highest removal efficiency of CO₂, followed by potassium threonate (PT), MEA, amino-2-methyl-1-propanol (AMP), diethanol amine (DEA), and MDEA in sequence. In addition, the results revealed that the CO₂ removal efficiency was favored by absorbent flow rate and liquid temperature, while the gas flow rate has a reverse effect. The simulation results proved that the hollow fiber membrane contactors have a good potential in the area of CO₂ capture.

Abstract The hydroisomerization of pure n-pentane over H-mordenite supported Pt-catalyst was investigated in a fixed bed reactor by changing reaction parameters such as temperature, pressure, and WHSV, as well as the H2/HC ratio. The maximum yield of isopentane over Pt/mordenite catalyst was achieved at 220 °C and a relatively low reaction pressure. To address the effect of feed composition on the catalytic performance of the samples, the catalysts were assessed for activity and selectivity in the isomerization of a mixture consisting of n-pentane (70 wt.%) and isopentane (30 wt.%) at 220 °C. The effects of pressure, WHSV, and H2/HC ratio on the catalyst performance were also studied using binary mixtures of the pentane isomers as a feedstock. It was observed that an effect of WHSV and H2/HC on the catalytic performance was similar to its behavior in pure n-pentane isomerization, while the conversion of n-pentane in the binary mixture showed a different trend and had a minimum value at 1.5 bar. It could be due to the presence of isopentane in feed and adsorption phenomenon of binary mixture on mordenite-supported catalyst.

Abstract In this work, the dispersed phase holdup in a Kühni extraction column is predicted using intelligent methods and a new empirical correlation. Intelligent techniques, including multilayer perceptron and radial basis functions network are used in the prediction of the dispersed phase holdup. To design the network structure and train and test the networks, 174 sets of experimental data are used. The effects of rotor speed and the flow rates of the dispersed and continuous phases on the dispersed phase holdup are experimentally investigated, and then the artificial neural networks are designed. Performance evaluation criteria consisting of R², RMSE, and AARE are used for the models. The RBF method with R², RMSE, and AARE respectively equal to 0.9992, 0.0012, and 0.9795 is the best model. The results show that the RBF method well matches the experimental data with the lowest absolute percentage error (2.1917%). The rotor speed has the most significant effect on the dispersed phase holdup comparing to the flow rates of the continuous and dispersed phases.

Abstract The Khaviz oil field located in Dezful embayment is one of Iran’s southwest oil fields. In this study, a total of 28 cutting samples from Kazhdumi formation (well No. KZ1, Khaviz oil field) were subject to geochemical investigation using Rock-Eval pyrolysis for the first time. The results of pyrolysis indicated that Kazhdumi source rock has significant hydrocarbon production potentiality and already entered the oil generation window. As inferred from the diagram of OI versus HI, Kazhdumi source rock contains organic matter type II kerogen deposited in paralic environment with anoxic to suboxic conditions. Using the diagram of S₂ versus TOC, the absorbed carbon content, neutral carbon, and active carbon were calculated to be 0.42, 0.39, and 2.43 wt.% respectively.

Abstract Hot potassium carbonate (PC) solution in comparison with amine solution had a decreased energy of regeneration and a high chemical solubility of . To present vapor and liquid equation (VLE) of this system and predict  solubility, the ion specific non-electrolyte Wilson-NRF local composition model (isNWN) was used in this study; the framework of this model was molecular. Therefore, it was suitable for both electrolyte and non-electrolyte solutions. The present research employed the NWN model and the Pitzer-Debye-Hückel theory in order to assess the contribution of the excess Gibbs energy of electrolyte solutions in a short and long range. The data of  solubility in water and the system of aqueous  were correlated in the model considering a temperature range of  and a pressure range of and . The average absolute error of ( ) and ( ) systems were  and  respectively. The results and comparisons with other models proved that the experimental data were exactly correlated in the model.

Abstract In recent years, the use of natural surfactants as surface active agents in chemical methods of oil recovery over chemical surfactants has been under consideration due to the absence of environmental problems. In this study, a new plant, Albizia julibressin (Albizia), was introduced as a natural surfactant. Our novelty resides in a unified approach that deals with the introduction of Albizia julibressin (Albizia) as a new natural surfactant, interpretation of the chemical EOR objectives, interface reactions, and the induced optimization to improve oil recovery. For this purpose, the plant was extracted using Soxhlet extraction method, aqueous base solutions and interfacial tension between natural surfactant aqueous solutions and kerosene as an oil phase were measured by pendant drop method. The critical micelle concentration structures formed by this material has been determined by interfacial tension tests and confirmed by electrical conductivity tests. The results show that Albizia extract at 3.5 wt% begins to form micelles structures, which is the critical concentration of Albizia plant micelles. At this concentration, the interfacial tension between the deionized water and the oil phase is reduced from 34 mN /m to 10 mN/m, which indicates a significant decrease in interfacial tension by this plant. Carbonate rock was employed to core flooding experiments in order to investigate the effect of Albizia extract (AE) on oil recovery. Also based on results, by using AE, wettability of oil-wet carbonate rocks, was altered from about 165.02◦ to 86.59◦. Finally, AE enhanced ultimate oil recovery about 11.6% of original oil in place in tertiary recovery for a carbonate rock.

Abstract The purpose of this study is to investigate bending moment and the axial load capacity of a pressurized pipe suffering from a through-wall circumferential crack repaired by a composite sleeve. The three-dimensional finite element method (FEM) was adopted to compute the results, and the failure assessment diagram (FAD) was employed to investigate the failure behavior of the repaired pipe. The findings revealed that, for the investigated range of applied loads and angles of the crack, the interaction of brittle and ductile failure modes is negligible. Additionally, the yield strength of the cracked pipe was considered as reference stress to achieve a conservative design. Two cases of the combined loading state consisting of internal pressure/bending moment and internal pressure/axial tensile force were investigated. Repairing the crack under combined loadings using carbon-epoxy composites was studied where the influences of various parameters, including internal pressure, crack angle, and the composite patch thickness on the capacity of the cracked pipe to withstand bending moment and axial load were included. The results indicated that the bending moment and axial load capacities of the cracked pipe depend on internal pressure, crack angle, and the composite patch thickness; nevertheless, the crack angle is the main parameter. A composite sleeve can increase both bending moment and axial load capacity of the cracked pipe, but bending moment can be increased further than axial load. Using the composite patch to repair the cracked pipe caused the bending moment capacity to improve from 14.28% to 120%. On the other hand, the composite patch raised the axial load capacity from 5.1% to 93.5%. Additionally, an increase in the composite patch thickness caused the axial load capacity to extend more than bending load capacity.

Abstract Heat EXchangers (HEX) that are used in City Gate Station (CGS) systems are modeled numerically to recover the exhaust waste heat. It was tried to find the best viscous model to obtain results in accordance with experimental results and to change the heat exchanger design. This HEX is used for recovering heat from exhaust flue gas with a mixture of 40% water and 60% ethylene glycol as the cooling fluid. Then, the effects of sizes and numbers of fins and tube rows on recovered heat rate were investigated under various pump speeds. As the first step in solving the problem, SST k–ω and RNG k–ε suitable viscous models were chosen for these kinds of problems. Secondly, a new HEX is designed at a fixed coolant speed, pipe and fin thickness, and shell dimension because of operational constraints. Finally, the best HEX with the minimum pressure drop (minimum fin number) is numerically analyzed, and the new HEX specifications were extracted. 

Abstract This study presents a robust and rigorous method based on intelligent models, namely radial basis function networks optimized by particle swarm optimization (PSO-RBF), multilayer perceptron neural networks (MLP-NNs), and adaptive neuro-fuzzy inference system optimized by particle swarm optimization methods (PSO-ANFIS), for predicting the equilibrium and kinetics of the adsorption of sulfur and nitrogen containing compounds from a liquid hydrocarbon model fuel on mesoporous materials. All the models were evaluated by the statistical and graphical methods. The predictions of the models were also compared with different kinetics and equilibrium models. The results showed that although all the models lead to accurate results, the PSO-ANFIS model represented the most reliable and dependable predictions with the correlation coefficient (R²) of 0.99992 and average absolute relative deviation (AARD) of 0.039%. The developed models are also able to predict the experimental data with better precision and reliability compared to literature models.

Abstract Resonances are intrinsic characteristics of an elastic object, which are completely independent of the source of excitation. The appropriate utilization of the information contained within the resonance spectra and the identification of the resonance frequencies of the object can be used as a potent tool for material characterization. In this paper, a new mathematical model for the wave diffraction from a cylindrical nanofiber encased in an elastic matrix is introduced. The new model is used to evaluate the scattered pressure field resulting from normal insonification on a single nanofibrous composite. It is shown that there are specific resonances, which arise from the surface/interface energy between the nanofiber and solid matrix. They can be used to determine the characteristics and properties of fibrous nanocomposites.

Abstract In this research, the reactive absorption of carbon dioxide in an aqueous solution of NH₃, H₂O, and NaOH has experimentally been investigated. The experiments were carried out in an absorption pilot plant in different operational conditions. The composition and temperature of both gas and liquid phases were obtained during the column height. The concentration of molecular and ionic species in the liquid phase was calculated using the principles of electrolyte and Pitzer model. In the experiments, the effect of sodium hydroxide concentration on carbon dioxide absorption was considered. The results revealed that the concentrations of ionic and molecular species in the liquid phase drastically influence the absorption rate of carbon dioxide. Also, the results showed that the absorption rate of carbon dioxide was increased by increasing ammonia and sodium hydroxide concentration.

Abstract The aim of this work is to synthesize and investigate the performance of yttria-doped zirconia solgel coatings in the chemical corrosion prevention of zircaloy-4 (zirconium alloy) in a 1 N H2SO4 environment. The influence of four different molar ratios of water to alkoxide, namely 1, 4, 12, and 20, on the coating quality and its corrosion prevention performance was investigated. Differential thermal analysis and thermogravimetric analysis (DTA-TG) revealed the coating formation process. Surface morphology was examined using scanning electron microscopy (SEM). Microscopic features were obtained by employing energy dispersive spectroscopy (EDX) and X-ray diffraction (XRD). Wet corrosion performance was evaluated by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The EDX results approved that the amount of the yttria doped in zirconia was about 8 wt.%. The XRD results showed that the crystallization of zirconia started near 400 °C. The SEM results showed that denser cracks were formed at a water/alkoxide molar ratio of 4. The electrochemical tests revealed that, as the molar ratio of water to alkoxide was increased beyond 4, the coating quality was damaged and the best protection performance was achieved at a water/alkoxide molar ratio of 4.

Abstract One of the mostly used enhanced oil recovery methods is the injection of water or gas under pressure to maintain or reverse the declining pressure in a reservoir. Several parameters should be optimized in a fluid injection process. The usual optimizing methods evaluate several scenarios to find the best solution. Since it is required to run the reservoir simulator hundreds of times, the process is very time consuming and cumbersome. In this study a new intelligent method of optimization, called “global dynamic harmony search” is used with some modifications in combination with a commercial reservoir simulator (ECLIPSE^®) to determine the optimum solution for fluid injection problem unknowns. Net present value (NPV) is used as objective function to be maximized. First a simple homogeneous reservoir model is used for validating the developed method and then the new optimization method is applied to a real model of one of the Iran oil reservoirs. Three strategies, including gas injection, water injection, and well placement are considered. Comparing the values of NPV and field oil efficiency (FOE) of gas injection and water injection strategies, it is concluded that water injection strategy surpasses its rival. Considering water injection to be the base case, a well placement optimization is also done and best locations for water injection wells are proposed. The results show the satisfying performance of the algorithm regarding its low iterations.

Abstract This paper presents a new multi-sensor data fusion method based on the combination of wavelet transform (WT) and extended Kalman filter (EKF). Input data are first filtered by a wavelet transform via Daubechies wavelet “db4” functions and the filtered data are then fused based on variance weights in terms of minimum mean square error. The fused data are finally treated by extended Kalman filter for the final state estimation. The recent data are recursively utilized to apply wavelet transform and extract the variance of the updated data, which makes it suitable to be applied to both static and dynamic systems corrupted by noisy environments. The method has suitable performance in state estimation in comparison with the other alternative algorithms. A three-tank benchmark system has been adopted to comparatively demonstrate the performance merits of the method compared to a known algorithm in terms of efficiently satisfying signal-tonoise (SNR) and minimum square error (MSE) criteria.

Abstract The current study assesses the root causes of hydrogen blisters on low strength carbon steel equipment. For this purpose, some experiments including hardness test, non-destructive test (NDT), metallography, and fractograpghy are conducted. The microstructure of two blisters is assessed by means of optical microscopy and scanning electron microscopy (SEM). The microstructural studies show that the steel plate has some inclusions and banded ferrite/pearlite structure. The energy dispersive x-ray spectroscopy (EDS) results indicate that these inclusions mainly contain Mn, S, Al, Ca, and Si. The results show that the inclusions and planar imperfections found in the NDT have been the nucleation locations for blisters in the plate. Remediation action plans are recommended to prevent further occurrence and growth of hydrogen blisters.

Abstract The enormous demands for metal implant have given rise to a search for cheap material with good bio-tolerability and resistance to corrosion. Although stainless steel has these properties and is widely used for this purpose, its long term application is still a concern. The corrosion resistance of stainless steel depends on the passive layer. Herein, chemical surface treatment, including passivation, electropolishing, and acid cleaning is used for improving the corrosion-resistance property of AISI 316L and 304L. Cyclic polarization, electrochemical impedance spectroscopy, and EDX analysis were used to investigate the properties obtained thereby. Finally, the corrosion resistance of the untreated and modified specimens was compared. The results show that the corrosion behavior of the passivated and electropolished specimens is improved.

Abstract Arguably, the natural gas transmission pipeline infrastructure in Iran represents one of the largest and most complex mechanical systems in the world. The optimization of large gas trunk lines known as IGAT results in reduced fuel consumption or higher capability and improves pipeline operation. In the current study, a single-objective optimization was conducted for Khormoj compressor station on the Iranian gas trunk line V (IGAT5). The system consists of over 504 kilometers of 56-inch pipeline from South Pars to Aghajari. This system passes through a tortuous terrain with changes in elevation which makes the optimization process even more challenging. Genetic algorithm (GA) was used in this optimization along with detailed models of the performance characteristics of compressors. The results show that in stations having the same compressor in parallel the minimum power (energy) consumption is reached when split flow in all the compressors is the same.

Abstract A fundamental study of scale formation of calcium carbonate (CaCO3) for producing oil wells has been carried out. This article presents the study of the prediction of salt deposition in two different synthetic formation waters and investigates the effects of temperature and pressure on calcium carbonate precipitation. The dependence of the induction period of the precipitation of calcium carbonate on the concentration of calcium ions was studied. In order to study the chemical scale inhibition, the most effective inhibitors, which are based on the risk analysis of scaling and laboratory reagent selection, were examined for evaluating the performance of salt inhibition. In this work, a new multi-component inhibitor was made and its scale effectiveness was evaluated at different concentrations. The developed inhibitor was mixed with other inhibitors to prevent calcium carbonate precipitation. The observations showed the synergetic inhibition effect on the scale inhibition at different concentrations of scale inhibitors. The new inhibitor provided high scale effectiveness at specific concentrations and low corrosion activity.

Abstract As an alternative to chromate conversion coatings, rare-earth coatings especially cerium, because of the low toxicity, have attracted considerable attention. Using dip immersion method, cerium-based conversion coating was deposited on aluminum 2024. Corrosion resistance was studied in 3.5 wt.% NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy, and surface methods. The coated samples revealed a considerable decrease in corrosion rate and with increasing immersion time up to 1200 s, the coating resistance increased. Electrochemical impedance data showed that the aluminum charge transfer resistance was increased in the existence of cerium oxide conversion coatings. Using energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM), the chemical composition and surface morphology were also evaluated.

Abstract In some engineering fields, wear resistance and a low friction coefficient are required at the same
time. In this research, PTFE nanoparticles and carbon nanotubes were co-deposited within Ni-P
matrix to obtain an Ni-P-PTFE-CNT hybrid coating for wear resistance and a low friction coefficient.
The tribological properties of the deposits were evaluated by pin on disc tribometer. The morphology
of the coatings and worn surface was evaluated by scanning electron microscopy. However, the
results showed that the addition of PTFE nanoparticles to the Ni-P electroless coating caused the
friction coefficient to decrease to values lower than 0.2, which led to an improvement in friction
behavior because of its self-lubricity properties; it, however, decreased the strength of coating due to
polymeric and soft structure of the molecules. The simultaneous incorporation of PTFE nanoparticles
and carbon nanotubes can provide the properties of both molecules and increased the strength of
coating with a low friction coefficient and self-lubricity properties. Therefore, the wear rate and the
degradation of surface were decreased during the wear process.

Abstract The rate of penetration (ROP) is one of the vital parameters which directly affects the drilling time and costs. There are various parameters that influence the drilling rate; they include weight on bit, rotational speed, mud weight, bit type, formation type, and bit hydraulic. Several approaches, including mathematical models and artificial intelligence have been proposed to predict the rate of penetration. Previous research has showed that artificial intelligence such as neural network and adaptive neuro-fuzzy inference system are superior to conventional methods in the prediction of drilling rate. On the other hand, many complicated analytical ROP models have also been developed during recent years that are able to predict drilling rate with a high degree of accuracy. Therefore, comparing different approaches to find the most accurate model and assess the conditions in which each model works well can be highly effective in reducing drilling time as well as drilling cost. In this study, Hareland-Rampersad (HR) model, Bourgoyne and Young (BY) model, and an adaptive-neuro-fuzzy inference system (ANFIS) are employed to predict the drilling rate in the South Pars gas field (SP) offshore of Iran, and their results are compared to find the best ROP-prediction model for each formation. A database covering the drilling parameters, sonic log data, and modular dynamic test data collected from several drilling sites in SP are used to construct the mentioned models for each formation. The results show that when a large amount of data is available, the ANFIS is more accurate than the other approaches in predicting drilling rate. In the case of ROP models, BY model works considerably better than HR model for the majority of the formations. However, in formations where some drilling parameters are constant, but formation strength is variable, HR model shows better prediction performance than BY model.

Abstract Microbial enhanced oil recovery (MEOR) is an economical method used to improve the oil recovery from reservoirs. In the MEOR techniques, by applying different microorganisms, a variety of products such as bioacid, biogas, biosurfactant, and biopolymer are generated, among which biosurfactant, one of the important metabolites, is produced by bacteria. It is worthy to note that bacteria are suitable candidates to enhance oil recovery due to their small size, rapid growth, capability of tolerating reservoir conditions, and production of different metabolites. Therefore, in this research, two bacteria, namely Enterobacter cloacae subsp with PTCC: 1798 isolated from oil-contaminated soil in south of Iran and Acinetobacter Calcoaceticus with PTCC: 1318, are used to produce biosurfactants.
In order to evaluate the performance of generated biosurfactants, ex-situ flooding tests were performed in a glass micromodel to visualize the oil displacement and fluid front flow. In addition, water flooding is performed as a common EOR method for the better investigation of the produced biosurfactants. The results represented that injecting Enterobacter with a salinity concentration of 6% and Acinetobacter with a salinity concentration of 3% respectively increases the oil recovery factor by 27 and 35% compared to water flooding. In other words, the highest reduction in interfacial tension is achieved by the biosurfactant produced from Enterobacter and Acinetobacter at 6% and 3% salinity respectively, and the sequent changes in the interfacial tension are from 45 to 7 and 45 to 4 mN/m.

Abstract Pentachlorophenol (PCP) is a very hazardous compound which enters into the environment by industries such as refineries and petrochemicals. As its biological degradation is very slow, this use may cause the pollution of soils and groundwater; with the recent emergence of pentachlorophenol contamination as an important drinking water quality issue, finding an easy, economical, and useful method to remove it has been attracted interest. In this study, the performance of an electro-Fenton process (EFP) for the elimination of PCP from an aquatic environment was evaluated. The effects of important operational variables such as reaction time, pH, the applied voltage, and the distance between the electrodes on the degradation of solution were investigated. The maximum PCP removal was obtained at a distance of 3 cm, a pH of 3, a voltage of 24 volt, and the treatment time of 40 min. This study demonstrated that the distance between the electrodes, pH, the applied voltage, and the treatment time have significant effects on the electron-Fenton process and this process is suitable for the treatment of PCP-polluted waste waters.