Iranian Journal of Oil and Gas Science and Technology

Abstract A new method for the synthesis of nano zero-valent iron (nZVI) was developed in the present study. Ultrasonic waves, as a novel method, were used to synthesize the nanoparticles. The morphology and surface compositions of the particles were characterized by using FESEM, XRD, BET, and particle size analyzer. The synthesized nanoparticles were then utilized as a Fenton-like catalyst to degrade of hydrocarbon contaminants of soil. The effect of using ultrasonic waves in combination with nZVI for hydrocarbon degradation was also investigated. The effects of ultrasonic power, nZVI concentration, pH, hydrogen peroxide concentration, and temperature on remediation were studied. It was found that the new nZVI synthesized by an ultrasound-assisted method had high efficiency in soil remediation. The results indicated that the efficiency of removing hydrocarbons by nZVI was 98.57%. Finally, the optimum conditions of degradation were obtained when pH, ultrasonic power, nZVI concentration temperature, and hydrogen peroxide concentration were respectively equal to 3.5, 500 W, 0.4 gr.l-1, 40 °C, and 30 mM.

Abstract This research reported a new method of removal of Pb⁺²from water by using a nano zero valent iron (nZVI) assisted ultrasonic wave. At first, nZVI was synthesized by an ultrasound assisted method. Particles morphology and surface composition were characterized by FESEM, XRD, and EDX. The XRD patterns showed that the crystallinity of the nZVI prepared using ultrasonic conditions was higher than the conventional method. According to the EDX pattern, 67% of particle composition was nZVI. The synthesized nanoparticles were then utilized as a Fenton-like catalyst for the removal of Pb⁺²from water using an ultrasound assisted method. In the present study, ultrasound power, temperature effects, nZVI, and reaction time were optimized. From the studies, it has been observed that removal does not increase indefinitely with an increase in ultrasound power, but it instead reaches an optimum value and decreases with a further increase in the ultrasound power. The removal of Pb⁺²increased with increasing temperature, nZVI, and H₂O₂ concentration. The result indicated that the efficiency of hydrocarbon removal by this novel method was 97.87%.

Abstract Commercial hydrocarbon discoveries in the Cretaceous of the southern Persian Gulf basin provide direct evidence that there is an effective petroleum system associated with the Cretaceous series. The revised models of thermal maturity in this region are needed to investigate lateral and stratigraphic variations of thermal maturity, which have not so far been addressed in detail for this part of the Persian Gulf. Such thermal maturity models are required to delineate the existing play assessment risks and to predict properties in more deeply buried undrilled sections. This study uses two dimensional basin modeling techniques to reconstruct maturity evolution of the Cenomanian Middle Sarvak source rock, presumably the most likely source for these hydrocarbons. The results indicate that an estimated 900 meter difference in the depth of burial between the southeastern high and the adjacent trough tends to be translated into noticeable variations at both temperature (135 °C versus 162 °C) and vitrinite reflectance (0.91% versus 1.35%). Since the organic matter in the mentioned source rock is of reactive type II, these could cause a shift of about 18 million years in the onset of hydrocarbon generation over respective areas.

Abstract In this paper, the potentials of using particles, especially nanoparticles, in enhanced oil recovery is investigated. The effect of different nanoparticles on wettability alteration, which is an important method to increase oil recovery from oil-wet reservoirs, is reviewed. The effect of different kinds of particles, namely solid inorganic particles, hydrophilic or hydrophobic nanoparticles, and amphiphilic nanohybrids on emulsion formation (which is cited as a contributing factor in crude oil recovery) and emulsion stability is described. The potential of nanohybrids for simultaneously acting as emulsion stabilizers and transporters for catalytic species of in situ reactions in reservoirs is also reviewed. Finally, the application of nanoparticles in core flooding experiments is classified based on the dominant mechanism which causes an increase in oil recovery from cores. However, the preparation of homogeneous suspensions of nanoparticles is a technical challenge when using nanoparticles in enhanced oil recovery (EOR). Future researches need to focus on finding out the proper functionalities of nanoparticles to improve their stability under harsh conditions of reservoirs. 

Abstract The present paper examines the effect of two effective factors, namely motivation and job satisfaction, on the effectiveness of on-the-job training (OJT) in the Iranian Oil Industry. Therefore, two main hypotheses and six submain hypotheses were defined and all were confirmed. The population of the study was composed of oil industry official employees. The sample of research was taken from the employees of three main companies of oil industry: petrochemical, oil refinery and distribution, and national Iranian oil company in the north, center, and south areas. It was taken by a simple random method with drawing lots. Its size was 171 people according to Morgan table and Cochran formula. Questionnaires developed by the researchers formed the data collection tool. The hypotheses were examined, and the data were analyzed by multiple regression tests. The results showed significant relationship of job satisfactions and staff motivation with OJT courses. Stronger dependency was found between motivations and job satisfaction variables with the effectiveness of attitude training courses.

Abstract Seismic modeling aids the geophysicists to have a better understanding of the subsurface image before the seismic acquisition, processing, and interpretation. In this regard, seismic survey modeling is employed to make a model close to the real structure and to obtain very realistic synthetic seismic data. The objective of this study is to analyze the resolution and illumination of the fault by designing appropriate 3D seismic survey parameters. The ray-based seismic modeling was built using 2D seismic data, geological reports, and the well logs in one of the oil fields in the southwest of Iran. A pre-stack depth migration simulator was used to evaluate the survey geometry on the resulting seismic image. The results proved that a survey designer could improve the image of the target in a seismic section by applying the ray-based analyses, with respect to illumination and resolution studies.

Abstract In sour gas flares,  content like any other components in inlet gas influences adiabatic flame temperature, which, in turn, impacts on the pollutant emission. Wherever flame temperature increases, the endothermic reaction between  and  is accelerated, which means higher  emission to the atmosphere. In this work, we developed an in-house MATLAB code to provide an environment for combustion calculations. Then, this written code was used to perform sensitivity analyses on  content, air temperature, and excess air ratio in sour gas flares. We used Environmental Protection Agency (EPA) reports to assign weighting indexes to each air contaminant according to its harmfulness to environment; thereafter, sour gas flaring conditions were optimized for two real field case studies, namely Ahwaz (AMAK) and South Pars, to reach the minimum integrated pollutant concentrations. The results show that each 2% increase in the  content of the entrance feed may produce 0.3% additional  in the exhaust. The results also confirm that decreases of 20 °F and 50 °F in the oxidant temperature cause  emission to reduce by 0.5% to 1% respectively. Finally, to verify and validate our results acquired from the written MATLAB code, FRNC 2012 industrial software was used to duplicate the oxidation results for the two sour flare case studies.

Abstract In this work, adsorbents, namely bentonite and sludge, modified by iron and copper were used to remove the H₂S and mercaptan from Kermanshah refinery. The used adsorbents are inexpensive materials, which substantially decrease the operational costs. The structure of the adsorbents was analyzed using scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The effects of gas and flow rate on the H₂S and mercaptan removal were also studied. The results indicated that the bentonite modified by iron has a high capacity for removing H₂S (32.256 mg/g) and mercaptan (0.98 mg/g). Moreover, the adsorption capacity of the sludge modified by copper for removing H₂S and mercaptan was 11.18 and 0.81 mg/g respectively. Furthermore, by increasing the flow rate and concentration of H₂S and mercaptan, H₂S and mercaptan concentrations in the sludge output gas increased, but no considerable change was observed in the bentonite output gas.

Abstract In this research, the effects of important parameters, including the molar ratio of acetic acid to sulfur(S) , sonication time, temperature, and hydrogen the molar ratio of peroxide to sulfur on the performance of ultrasound-assisted oxidative desulfurization were studied using the response surface method (RSM). To this end, a model fuel containing n-decane and dibenzothiophene at a concentration of 1000 ppm was used. It was found out that the temperature and acetic acid/S molar ratio were the most influencing parameters affecting the conversion of sulfur compound. The synergistic effects of the parameters were also investigated, and it was discovered that the maximum conversion of dibenzothiophene reached 98.59% when H₂O₂/S, acetic acid/S, temperature, and sonication time were set to 167, 330, 80 °C, and 30 min respectively. Finally, the apparent kinetics of dibenzothiophene oxidation and the activation energy of reaction were presented.

Abstract Chemometric methods can enhance geochemical interpretations, especially when working with large datasets. With this aim, exploratory hierarchical cluster analysis (HCA) and principal component analysis (PCA) methods are used herein to study the bulk pyrolysis parameters of 534 samples from the Persian Gulf basin. These methods are powerful techniques for identifying the patterns of variations in multivariate datasets and reducing their dimensionality. By adopting a “divide-and-conquer” approach, the existing dataset could be separated into sample groupings at family and subfamily levels. The geochemical characteristics of each category were defined based on loadings and scores plots. This procedure greatly assisted the identification of key source rock levels in the stratigraphic column of the study area and highlighted the future research needs for source rock analysis in the Persian Gulf basin.

Abstract The influences of several operating factors on the viscosity of the Isfahan refinery waxy crude oil sample are studied through conducting some rheological shear rotational tests. The Taguchi design method is adopted to determine the impact of factors such as shear rate, temperature, cooling rate, wax content, and asphaltene content on the viscosity of the waxy crude oil. The results show that temperature with a contribution of 53.61% is the most influential factor. The wax content, shear rate, and asphaltene content have a contribution of 20.86, 14.75, and 3.11% respectively. The cooling rate does not have a statistically significant effect on the viscosity. The results of the rheological oscillatory tests confirm that the temperature and wax content change the viscoelastic properties of the waxy crude oil completely. An increase in the wax content from 12 to 22 wt.% raises the wax appearance temperature (WAT) from 19.1 to 34.9 °C and improves the gel point from 13 to 34.1 °C. By decreasing the temperature or increasing wax content, the viscoelastic nature of the oil sample changes from a viscoelastic fluid to a viscoelastic solid.

Abstract Since the development bloom in unconventional reservoirs in North America, total organic carbon (TOC) has become a more essential parameter, as the indicator of the efficiency of these reservoirs. In this paper, by using conventional well logs and NMR log data, the TOC content of an unconventional reservoir in West Africa is estimated. Passy’s, Issler’s, and Schmoker’s methods were used as indirect wireline methods to estimate TOC content, along the well paths. Afterward, NMR log data, as a direct method, was used to provide more precise calculations of TOC. Both methods showed almost similar trends, with the NMR method indicating lower values for the TOC. Then, an adjusted Schmoker equation was proposed, which showed the best fit between NMR and conventional well logs results. By using the equation, the TOC content was calculated in three other wells, where NMR data were unavailable. The results were then used to prepare a 3D model of the TOC distribution, within the reservoir.

Abstract Flaring of gas often having high heating value results in considerable economic and energy losses in addition to significant environmental impacts. Power generation through combined gas and steam turbine cycles may be considered as a suitable flare gas recovery process. Thermal sea-water desalination is a process that requires a considerable amount of heat; hence it may be used in downstream of power generation cycles. Energy is the largest section of the water generation cost of all desalination processes. The energy cost of thermal distillation sea-water plants is close to 50-60% of water generation costs. In the current study, the generation of power and desalinated water through the gas turbine cycle, steam cycle, and multistage flash (MSF) method using flare gas of cheshmeh khosh are investigated. The economic parameters related to the different scenarios considered for the production of power and water are evaluated in the current research. According to the economic evaluation carried out, the most economically profitable scenarios for the investigated co-generation plant is generating as much as possible power in the steam turbine and using the remaining heat in the low-pressure outlet steam in the MSF desalination process. The results show that by increasing steam turbine outlet pressure from 3 bar to 78 bar, power and water generation is changed from 697 to 581 MW and 1557 to 2109 m3/h, respectively. Also, by increasing the outlet pressure of the steam turbine from 3 to 78 bar, the total capital cost is changed from 1177 to 1192 MUSD, and the operating cost is changed from 117.85 to 117 MUSD/year. Finally, operating profit will decrease from 300 to 50 MUSD/year, and payback time will change from 3.92 to 4.75 years.

Abstract Rock-Eval pyrolysis is a thermal method petroleum geologists use to evaluate source rock characteristics and obtain geochemistry parameters. However, there are misconceptions and misuses in exceptional cases that could lead to erroneous conclusions after using the Rock-Eval pyrolysis data to evaluate the properties of organic matter. However, a cross-plot of petroleum potential (S₂) versus total organic carbon (TOC) is a useful tool for solving issues and checking the accuracy of the geochemistry parameters. The graph provides the correction criteria for the S₂, hydrogen index (HI), and kerogen types. As well as the graph measures the adsorption of hydrocarbon by the mineral matrix. In addition, this article demonstrates a manner based on the data plot of S₂ versus TOC to detect bitumen or hydrocarbon contaminations. Based on our knowledge about the Garau formation as a possible source rock in the petroleum geology of Iran, a geochemistry study by Rock-Eval VI pyrolysis and LECO carbon analyzer has been conducted on many rock samples collected from different outcrops in the Lurestan province, Aligudarz region, from southwest of Iran, High Zagros. Plotting the data on a cross plot of S₂ versus TOC, drawing the regression line, and finding the regression equation are the best methods for determining the actual values of S₂ and HI parameters and bitumen/hydrocarbon contamination. Contamination creates a y-intercept in the graph of S₂ versus TOC, making geochemistry data unreliable in two study locations. The S₂ and HI data unrealistically increase, while the T_max values decline and reduce the thermal maturity of the organic matter from its actual status. The y-intercept of the graphs is removed, and the corresponding values are subtracted from the HI and S₂ to skip the effect of contamination and obtain the actual geochemistry parameters. The cause of contamination in the Garau formation is the adhesion of heavy bitumen to organic facies due to the covalent bonds between carbon and hydrogen ions.

Abstract Recently, nanoparticles have been used to improve oil and gas production volume and enhance oil recovery (EOR). Based on our recent research, using nanoparticles such as silica and calcium oxide has a good potential for changing mechanisms in the porous media, such as interfacial tension and wettability. Low permeability carbonate plugs were selected to determine the application of nanoparticles in the porous media. Two main steps were used: 1) Using CaO and SiO₂ nanoparticles for wettability alteration, interfacial tension reduction, and improving fluid flow through porous media, and 2) Surveying the application of nanoparticles to the water alternating gas (WAG) (nanoparticles (NCs)-assisted WAG) test. The zeta potential values were stable at –56.4 ± 2 mV and –44.0 ± 3 mV for calcium oxide and silica nanoparticles, respectively, at an optimum nanoparticle concentration of 15 ppm. Calcium oxide and silica nanoparticles effectively altered the wettability from oil-wet to water-wet by surveying the intersection of two-phase relative permeability. Moreover, CaO nanoparticles performed better in low permeability carbonate porous media than SiO₂ nanoparticles regarding wettability alteration to water wetness. Based on the results and a better grade of CaO, it was selected for performing NCs-assisted WAG tests at WAG ratios of 1:1, 40 ℃, and 15 ppm. The recovery factor increased from 42.9% to 73% in the presence of CaO during NC-assisted WAG tests, and residual oil saturation decreased from 40.9% to 19.4%.

Abstract Experimental analysis and numerical simulation of CO₂ injection in oil and gas reservoirs are essential for CO₂ sequestration and enhanced oil recovery applications. However, experimental approaches are often expensive and time-consuming, while numerical methods require input parameters such as two-phase relative permeabilities. In this study, two-phase flow simulations are conducted using a numerical solver based on the phase-field approach under steady-state conditions to determine relative permeability curves. Specifically, flow simulations are performed in realistic porous media, and nonconstant fluid viscosity and density are incorporated, addressing limitations of previous studies. Therefore, the main contribution of this work is the determination of CO₂–oil relative permeabilities in realistic porous media extracted from micro-CT images under conditions of variable fluid viscosity and density. In addition, the influences of wetting properties and hysteresis on relative permeability behavior are investigated.
The numerical results indicate that increased wettability toward the injected fluid enhances displacement efficiency by shifting the intersection point of the relative permeability curves to the right, leading to higher oil recovery, particularly at larger contact angles corresponding to non-wetting conditions and at lower surface tensions. Furthermore, the separation between imbibition and drainage relative permeability curves, representing hysteresis effects, becomes more pronounced as wettability shifts toward larger contact angles. These findings demonstrate the capability of steady-state pore-scale simulations based on the phase-field approach to reliably determine CO₂–oil relative permeability curves when realistic porous media and nonconstant fluid properties are considered.

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