Iranian Journal of Oil and Gas Science and Technology

Abstract Rapid development of technologies, their increasing complexity and variety, together with limited organizational resources and efforts for survival in industrial competitions have made the task of appropriate technology selection a major challenge. The present research is aimed at the formulation of technology strategy related to oil production in one of the west Karoon oil fields in Iran. At the first, the processes and challenges of production in the studied oil field are recognized by the experts’ survey. Then, the priority of the challenges is evaluated and four key challenges of the considered field are recognized by using a paired comparison questionnaire and Chang Fuzzy AHP. In the next step, the existing and new technologies of oil production in the four recognized key challenges are determined. For each of the recognized technologies, the attractiveness assessment and capability assessment questionnaire are designed based on Jolly indexes and distribute in a sample composed of production engineering experts. Sampling is done by the non-random and purposive-judgmental method. Based on the results of the questionnaires, the attractiveness-capability matrix is designed by Morin’s model, and then based on the obtained technology portfolio, the strategies of each of the four areas are formulated and discussed.

Abstract The adsorption and separation properties of 3A zeolite are investigated by using Grand Canonical Monte Carlo (GCMC) simulation. To obtain the adsorption isotherms of water, methyl mercaptan, and methane on 3A zeolite, COMPASS Force Filed is used. The adsorption isotherms of the pure components and the ternary mixtures of water, methyl mercaptan, and methane on 3A zeolites are calculated. The Sips Model is taken into account for the description of water adsorption on 3A zeolite. In addition, the effects of pressure and temperature on the adsorption of components are examined. The results demonstrate that the water has high adsorption selectivity on 3A zeolite, and this kind of adsorbent is a good candidate for the dehydration of natural gas.

Abstract This work is a primary achievement in studying the CO₂ and N₂–oil systems. To predict gas-liquid relative permeability curves, a Shan-Chen type multicomponent multiphase lattice Boltzmann model for two-phase flow through 2D porous media is developed. Periodic and bounce back boundary conditions are applied to the model with the Guo scheme for the external body force (i.e., the pressure gradient). The influence of relationship between cohesion and adsorption parameters and the interfacial tension values in Young's equation, pore structure (micro scan image derived porous media response is compared with corresponding porosity and permeability ideal sphere pack structure), and saturation distribution on relative permeability curves are studied with the aim to achieve the realistic stable condition for the simulation of gas-liquid systems with a low viscosity ratio.

Abstract In this paper, using a one-dimensional simulation model, the reforming process of sour gas, i.e. CH₄, CO₂, and H₂S, to the various charged particles and syngas in a dielectric barrier discharge (DBD) reactor is studied. An electric field is applied across the reactor radius, and thus a non-thermal plasma discharge is formed within the reactor. Based on the space-time coupled finite element method, the governing equations are solved, and the temporal and spatial profiles of different formed charged species from sour gas inside the plasma reactor are verified. It is observed that the electric field increases radially towards the cathode electrode. Moreover, the electron density growth rate at the radial positions closer to the cathode surface is smaller than the one in the anode electrode region. Furthermore, as time progresses, the positive ions density near the anode electrode is higher. In addition, the produced syngas density is mainly concentrated in the proximity of anode dielectric electrode.

Abstract Several studies have shown that oil recovery significantly increased by low salinity water flooding (LSWF) in sandstones. However, mechanism of oil recovery improvement is still controversial. CO₂ that develops buffer in presence of water is expected as a deterrent factor in LSWF efficiency based on mechanism of IFT reduction due to pH uprising. No bright evidence in literature supports this idea.  Here, a set of core floods including a pair of CO₂ WAG and a pair of water injection tests are conducted and, the efficiency of LSWF and high salinity water flooding (HSWF) were compared for each pair. HSWF was followed by LSWF in tertiary mode. Results showed that not only CO₂ does not deteriorate LSWF recovery efficiency, but also improves recovery. Since CO₂-low salinity WAG showed best performance among types by constant pore volume injected. Positive results in both secondary and tertiary modes with Kaolinite free samples used here showed that Kaolinite release is not the critical phenomenon in LSWF brisk performance. Also different pressure behaviour of CO₂ WAG processes in comparison with reported behaviour of LSWF proves that LSWF performance may not depend on how pressure changes through flooding.

Abstract Cementation factor is a critical parameter, which affects water saturation calculation. In carbonate rocks, due to the sensitivity of this parameter to pore type, water saturation estimation has associated with high inaccuracy. Hence developing a reliable mathematical strategy to determine these properties accurately is of crucial importance. To this end, genetic algorithm pattern search is employed to find accurate cementation factor by using formation resistivity factor and the porosity obtained from laboratory core analyses with considering the assumption that tortuosity factor is not unity. Subsequently, particle swarm optimization (PSO) fuzzy inference system (FIS) was used for the classification of cementation factor according to the predominated rock pore type by using the input variables such as cementation factor, porosity, and permeability to classify the core samples in three groups, namely fractured, interparticle, and vuggy pore system. Then, the experimental data which was collected from Sarvak formation located in one of the Iran southwestern oil fields was applied to the proposed model. Next, for each class, a cementation factor-porosity correlation was created and the results were used to calculate cementation factor and water saturation profile for the studied well. The results showed that the constructed model could predict cementation factor with high accuracy. The comparison between the model presented herein and the conventional method demonstrated that the proposed model provided a more accurate result with a mean square error (MSE) of around 0.024 and led to an R² value of 0.603 in calculating the water saturation.

Abstract In this paper, the development of a new potassium carbonateon alumina support sorbent prepared by impregnating K2CO3 with an industrial grade of Al2O3 support was investigated. The CO2 capture capacity was measured using real flue gas with 8% CO2 and 12% H2O in a fixed-bed reactor at a temperature of 65 °C using breakthrough curves. The developed sorbent showed an adsorption capacity of 66.2 mgCO2/(gr sorbent). The stability of sorbent capture capacity was higher than the reference sorbent. The SO2 impurity decreased sorbent capacity about 10%. The free carbon had a small effect on sorbent capacity after 5 cycles. After 5 cycles of adsorption and regeneration, the changes in the pore volume and surface area were 0.020 cm3/gr and 5.5 m2/gr respectively. Small changes occurred in the pore size distribution and surface area of sorbent after 5 cycles.

Abstract

Abstract The performance of water flooding can be investigated by using either detail numerical modeling or simulation, or simply through the analytical Buckley-Leverett (BL) model. The Buckley-Leverett analytical technique can be applied to one-dimensional homogeneous systems. In this paper, the impact of heterogeneity on water flooding performance and fractional flow curve is investigated. First, a base one-dimensional numerical model is considered and then the numerical model is made and validated through comparison with the Buckley-Leverett fractional flow equation. Then, the model is extended to two dimensions and heterogeneity is incorporated in the modeling by using six different heterogeneous models. In particular, distributions for permeability values are considered. Fractional flow curves and water flooding performances are investigated for each individual model. A modification in the Buckley-Leverett fractional flow equation is discussed in order to consider the heterogeneity effects.  

Abstract Reaction furnace is the most important part of the Claus sulfur recovery unit and its performance has a significant impact on the process efficiency. Too many reactions happen in the furnace and their kinetics and mechanisms are not completely understood; therefore, modeling reaction furnace is difficult and several works have been carried out on in this regard so far. Equilibrium models are commonly used to simulate the furnace, but the related literature states that the outlet of furnace is not in equilibrium and the furnace reactions are controlled by kinetic laws; therefore, in this study, the reaction furnace is simulated by a kinetic model. The predicted outlet temperature and concentrations by this model are compared with experimental data published in the literature and the data obtained by PROMAX V2.0 simulator. The results show that the accuracy of the proposed kinetic model and PROMAX simulator is almost similar, but the kinetic model used in this paper has two importance abilities. Firstly, it is a distributed model and can be used to obtain the temperature and concentration profiles along the furnace. Secondly, it is a dynamic model and can be used for analyzing the transient behavior and designing the control system.

Abstract Enhanced oil recovery using nitrogen injection is a commonly applied method for pressure maintenance in conventional reservoirs. Numerical simulations can be practiced for the prediction of a reservoir performance in the course of injection process; however, a detailed simulation might take up enormous computer processing time. In such cases, a simple statistical model may be a good approach to the preliminary prediction of the process without any application of numerical simulation. In the current work, seven rock/fluid reservoir properties are considered as screening parameters and those parameters having the most considerable effect on the process are determined using the combination of experimental design techniques and reservoir simulations. Therefore, the statistical significance of the main effects and interactions of screening parameters are analyzed utilizing statistical inference approaches. Finally, the influential parameters are employed to create a simple statistical model which allows the preliminary prediction of nitrogen injection in terms of a recovery factor without resorting to numerical simulations.

Abstract In this paper, exergy and exergoeconomic analysis is performed on the recently proposed process for
the coproduction of liquefied natural gas (LNG) and natural gas liquids (NGL) based on the mixed
fluid cascade (MFC) refrigeration systems, as one of the most important and popular natural gas
liquefaction processes. To carry out this analysis, at first, the proposed process is simulated, and then
the exergy analysis of the process equipment is performed; finally, an economic model is used for the
exergoeconomic analysis. The results include cost of exergy destruction, exergoeconomic factor,
exergy destruction, and exergy efficiency. The results of the exergy analysis demonstrate that the
exergy efficiency of the proposed process is around 53.83%, and its total exergy destruction rate is
42617.5 kW at an LNG and NGL production rates of 68.99 kg/s and 27.41 kg/s respectively. The
results of exergoeconomic analysis indicate that the maximum exergoeconomic factor, which is
69.53%, is related to the second compressor in the liquefaction cycle and the minimum
exergoeconomic factor, which is 0.66%, is related to the fourth heat exchanger in the liquefaction
cycle. In this process, demethanizer tower holds the highest relative cost difference (100.78) and the
first air cooler in liquefaction cycle has the lowest relative cost difference (1.09). One of the most
important exergoeconomic parameters is the cost of exergy destruction rate. The second heat
exchanger has the highest exergy destruction cost (768.91 $/Gj) and the first air cooler in the
liquefaction cycle has the lowest exergy destruction cost (19.36 $/Gj). Due to the high value of fuel
cost rate (as defined in exergoeconomic analysis) in heat exchangers, their exergy destruction cost is
much higher than other devices.

Abstract Water saturation and cation exchange capacity are the most significant parameters used to calculate a hydrocarbon zone potential. In clean formations, by applying the famous Archie model, which assumes that in the formation the only electric conductor is the formation water, the water saturation can be calculated. Additionally, in shaly sand formations this assumption may not be true as the ions are associated with clay minerals and transport electricity.
We attempt to utilize some logs, as well as experimental data, to improve the water saturation calculations and the cation exchange capacity within shaly sand layers for an Iranian oil field. Therefore, several shaly sand models were considered for the calculations of these values for three wells of the Ahvaz oil field. The validity of the different models was controlled through the measured values of cation exchange capacity and water saturation on core samples. The comparative results show that cation exchange capacity and water saturation calculated using Ipek-Bassiouni model are more indicative of zone hydrocarbon potential with correlation coefficients of 0.91 and 0.95 respectively. The results of this study show the requirement for the I-B model in studied reservoir and its superiority compared to other models because it is on the basis of principles reflecting the formation water and clay counter ions conductive behavior. 
Concerning to this model, two cement exponents are incorporated to illustrate the electric current path tortuosity in clay bound water and free water. In the current work, cementation exponent in free water (m_f) and clay bound water (m_c) were estimated from pure shale and clean sand respectively. The results of this study are promising and can be simply extended in other similar neighboring shaly sand reservoirs.

Abstract In this work, the performance of four electrolyte models for prediction the osmotic and activity coefficients of different aqueous salt solutions at 298 K, atmospheric pressure and in a wide range of concentrations are evaluated. In two of these models, (electrolyte Non-Random Two-Liquid e-NRTL and Mean Spherical Approximation-Non-Random Two-Liquid MSA-NRTL), association between ions of opposite charges for simplification purposes is ignored and in the other two ones, (Associative Mean Spherical Approximation-Non-Random Two-Liquid AMSA-NRTL and Binding Mean Spherical Approximation BiMSA) association and solvation effects are considered. The predictions of these four models for the osmotic and activity coefficients of electrolyte solutions at 298 K and atmospheric pressure are compared with the experimental data reported in the literature. This comparison includes, 28 different aqueous salt solutions including thio-cyanates, perchlorates, nitrates, hydroxides, quaternary ammonium salts and others. The results show, the performance of models that consider association effects are better than others especially for higher salt concentrations. However, the best performance belongs to BiMSA model which has some parameters with physical meaning.

Abstract One of the problems that sometimes occur in gas allocation optimization is instability phenomenon. This phenomenon reduces the oil production and damages downhole and surface facilities. Different works have studied the stability and suggested some solutions to override it, but most of them (such as making the well intelligent) are very expensive and thus they are not applicable to many cases. In this paper, as a new approach, the stability has been studied in gas allocation optimization problems. To prevent the instability, instability has been assumed as a constraint for the optimizer and then the optimizer has been run. For the optimization, first a genetic algorithm and then a hybrid of genetic algorithm and Newton-Quasi have been used, and their results are compared to ensure the good performance of the optimizer; afterwards, the effect of adding the instability constraint to the problem on production reduction have been discussed. The results show that the production loss with adding this constraint to the system is very small and this method does not need any additional and expensive facilities for preventing the instability. Therefore, the new method is applicable to different problems.

Abstract Efforts to enhance oil recovery through wettability alteration by nanoparticles have been attracted in recent years. However, many basic questions have been ambiguous up until now. Nanoparticles penetrate into pore volume of porous media, stick on the core surface, and by creating homogeneous water-wet area, cause to alter wettability. This work introduces the new concept of adding ZnO nanoparticles by an experimental work on wettability alteration and oil recovery through spontaneous imbibition mechanism. Laboratory tests were conducted in two experimental steps on four cylindrical core samples (three sandstones and one carbonate) taken from a real Iranian heavy oil reservoir in Amott cell. In the first step, the core samples were saturated by crude oil. Next, the core samples were flooded with nanoparticles and saturated by crude oil for about two weeks. Then, the core samples were immersed in distilled water and the amount of recovery was monitored during 30 days for both steps. The experimental results showed that oil recovery for three sandstone cores changed from 20.74, 4.3, and 3.5% of original oil in place (OOIP) in the absence of nanoparticles to 36.2, 17.57, and 20.68% of OOIP when nanoparticles were added respectively. Moreover, for the carbonate core, the recovery changed from zero to 8.89% of OOIP by adding nanoparticles. By the investigation of relative permeability curves, it was found that by adding ZnO nanoparticles, the crossover-point of curves shifted to the right for both sandstone and carbonate cores, which meant wettability was altered to water- wet. This study, for the first time, illustrated the remarkable role of ZnO nanoparticles in wettability alteration toward more water-wet for both sandstone and carbonate cores and enhancing oil recovery.

Abstract In this work, new correlations are proposed to predict the products yield of delayed coking as a function of CCR and temperature based on the experimental results. For this purpose, selected Iranian vacuum residues with Conradson carbon residue (CCR) values between 13.40-22.19 wt.% were heated at a 10 °C/min heating rate and thermally cracked in a temperature range of 400-500 °C in a laboratory batch atmospheric delayed coking reactor for 2 hours. The amount of distillate (C₅₊-500 °C) and coke yield were measured in all the experiments, and the gas (C₁-C₄) product yield was calculated based on mass balance between products and feedstock in each experiment. According to the developed functions, products yield changes with CCR value linearly and is a power function of temperature. The further investigation of the results show that by a 1 wt.% increase in CCR value, the distillate yield decreases by about 2.1 wt.%, but the amount of coke and gas yields rise by 1.2 wt.% and 0.9 wt.% respectively.

Abstract The effect of adding extra inlet channels on the operation of the Stairmand Cyclone has been investigated numerically. The Reynolds stress model (RSM) and Eulerian-Lagrangian method were used to investigate the complex turbulent flow and cyclone performance. The impacts of one-way coupling and two-way coupling models on the cyclone efficiency and the calculation of cut-off size diameter were examined. The results showed that a rise in channel number increases the tangential velocity and extends the Rankine vortex region. Moreover, in the four-inlet cyclone, the direction of flow changes unlike the one-inlet and two-inlet cyclones, and it behaves like a jet flow. According to the results, the collection efficiency and cut-off size diameter of the four-inlet cyclone are respectively about 10.78% higher and 35% lower than those of one-inlet configuration. Therefore, the performance of four-inlet cyclone is the highest among the three investigated configurations due to high tangential and axial velocities. A cyclone with more inlets has a more symmetrical flow pattern. Consequently, the four-inlet cyclone has the lowest flux of erosion among the others. The results of cyclone performance reveal a slight difference between one-way coupling and two-way coupling models.

Abstract Dilution is one of the various existing methods in reducing heavy crude oil viscosity. In this method, heavy crude oil is mixed with a solvent or lighter oil in order to achieve a certain viscosity. Thus, precise mixing rules are needed to estimate the viscosity of blend. In this work, new empirical models are developed for the calculation of the kinematic viscosity of crude oil and diluent blends. Genetic algorithm (GA) is utilized to determine the parameters of the proposed models. 850 data points on the viscosity of blends (i.e. 717 weight fraction-based data and 133 volume fraction-based data) were obtained from the literature. The prediction result for the volume fraction-based model in terms of the absolute average relative deviation (AARD (%)) was 8.73. The AARD values of the binary and ternary blends of the weight fraction-based model (AARD %) were 7.30 and 10.15 respectively. The proposed correlations were compared with other available correlations in the literature such as Koval, Chevron, Parkash, Maxwell, Wallace and Henry, and Cragoe. The comparison results confirm the better prediction accuracy of the newly proposed correlations.

Abstract Chlorine is a toxic and oxidizing gas used to purify drinking water in Iran. There has been no research on the effects of the gas or the explosion of the tanks, which could cause irreparable damage to people and the surrounding area. No such study has been carried out in the city of Abadan. To this end, Areal Locations of Hazardous Atmospheres (ALOHA) software, a computer program that helps professionals understand what will happen during a hazardous release, such as a chemical or fire, allows them to make plans to keep people safe. Thus, it was used to assess the magnitude of the gas release, the various risk zones, and the population at risk. In the event of damage to the 1-inch outlet valve of the tank, the gas release could be lethal up to a radius of 2 km, could be effective up to a radius of 6.2 km, and could be felt up to 10 km away. Due to the probability of occurrence and the location of the station in the wind direction, gas could reach many residents within a 5 km radius of the station. Therefore, as indicated by the results of the failure mode and effects analysis (FMEA) model evaluation, the implementation of preventive measures is strongly recommended in order to avoid gas release in settling tanks.

Abstract A steel catenary riser (SCR) attached to a floating platform at its upper end encounters fluctuations in and near its touchdown zone (TDZ), which causes the interaction with the seabed. Subsea surveys and the analysis of SCR’s indicated that the greatest stress and highest damage occurred near the touchdown point (TDP), where the SCR first touches the seabed. Nowadays, the linear seabed spring is carried out, and it is assumed as a flat seabed. Improved nonlinear hysteretic seabed models have recently been proposed, which simulate the different stiffness in the seabed response in the TDZ. In this study, an advanced hysteretic nonlinear SCR-seabed soil interaction model has been implemented to simulate the exact behavior of the riser in the vicinity of the touchdown zone. This paper focusses on the seabed trench, which develops progressively under the SCR due to repeated contact. Also, different important parameters such as water depth and material of riser have been investigated based on the Caspian Sea environmental conditions. This paper highlights the impact of trenches of different depths on the fatigue performance of riser at TDZ.

Abstract To provide supplementary oil recovery after the primary and secondary processes, enhanced oil recovery (EOR) techniques are introduced. Carbonated water injection (CWI) as an EOR method can improve sweep efficiency and the risk of gas leakage. On the other hand, the interfacial tension (IFT) is one of the key factors which can affect fluid displacement during the process of CWI greatly. Therefore, the analysis of the IFT on an oil-carbonated water-CO₂ system is vital. In this paper, the interfacial interactions of binary systems of asphaltenic crude oil (ACO), carbon dioxide (CO₂), and carbonated water (CW) at different pressures and at two temperatures of 40 °C and 50 °C and their effects on the oil spreading in the water phase in the presence of gas are experimentally investigated. The IFT measurements were performed by axisymmetric drop shape analysis (ADSA) technique for the pendant/rising oil drop case. It is found out that the equilibrium interfacial tension (EIFT) of the two systems of crude oil-CO₂ and water-CO₂ is reduced almost linearly with pressure but increased with temperature. Moreover, the pressure has an increasing and decreasing effect on the water-oil and CW-oil IFT’s respectively. However, temperature has a reverse effect for the both systems. Spreading coefficient (SC) concept would help better understand the oil recovery mechanisms and potential. The results show that SC curve has a minimum point value as a specific pressure, which increases with temperature. The presence of CO₂ in the water phase could strongly affect the oil spreading phenomenon through which oil recovery could be significantly enhanced.

Abstract Several mesoporous nickel-based catalysts with MgO-Al₂O₃ as the catalyst support were prepared using a co-precipitation method at a constant pH. The supports were prepared from the decomposition of an Mg-Al hydrotalcite-like structure which had already been prepared with Mg/Al=1. Prior to impregnating 10 wt.% nickel on the supports, the precursor was decomposed at several temperatures of 500, 600, 700, and 800 °C in order to elucidate the effect of calcination temperature on the physical and chemical characteristics of Mg-Al mixed oxides and the ultimate catalytic performance of the synthesized catalysts in the combined steam and dry reforming (CSDRM). The catalyst the precursor of which was calcined at 700 °C shows an excellent nickel dispersion and the highest activity among the other samples. It also exhibits the most stable performance during the long-term 36-hour run with high resistance against coke formation in the harsh condition of CSDRM.

Abstract In the present work, the exergy analysis and economic study of 3 different samples of threecomponent mixtures have been investigated (ESI>1, ESI≈1, and ESI<1). The feed mixture has been tested under three different compositions (low, equal, and high contents of the intermediate component). A quantitative comparison between simple and complex configurations, considering thermally coupled, thermodynamically equivalent, and divided-wall column (DWC) has been carried out. The results present that the best sequence could be found by TAC or exergy loss rate analysis. Complex sequences have greater exergy losses in comparison to simple sequences. Despite expectations, the Petlyuk sequence only performs well in a few cases and poorly on others. According to the results, as the amount of intermediate component in the feed increases, both TAC and exergy losses of each sequence increase. The results also demonstrated that the occurrence frequency as the best sequence for DWC, thermodynamically equivalent, thermally coupled, and basic sequences are 36%, 28%, 25%, and 11% respectively. According to authors’ best knowledge, a quantitative exergy and cost comparison (based on rigorous simulation and optimization) between these configurations have never been carried out all together before.

Abstract Separation of suspended droplets in a fluid flow has been a great concern for scientists and technologists. In the current study, the effect of the surface roughness on flow field and the performance of a gas-oil cyclone is studied numerically. The droplets and the turbulent airflow inside the cyclone are considered to be the discrete and continuous phases respectively. The Reynolds stress model (RSM) is employed to simulate the complex, yet strongly anisotropic, flow inside the cyclone while the Eulerian-Lagrangian approach is selected to track droplet motion. The results are compared to experimental studies; according to the results, the tangential and axial velocities, pressure drop, and Euler number decrease when the surface roughness increases. Moreover, the cyclone efficiency drops when the vortex length decreases as a result of a rise in surface roughness. The differences between the numerical and experimental results become significant at higher flow rates. By calculating the impact energy of droplets and imposing the film-wall condition on the walls, splash does not occur.