مجله پژوهش نفت
پیاپی 85-1 (بهمن و اسفند 1394)

In recent years, the Fischer-Tropsch synthesis has been considered as an important chemical process for natural gas conversion to liquid fuels. The abundant availability of natural gas and the increasing demand for different hydrocarbon products such as olefins, diesel, and waxes have led to a high level of interest to further develop this process. In this study, a multicomponent reaction engineering model for a slurry bubble column reactor on a commercial scale is developed in order to study the effects of different parameters on product distribution. The modeling results show that different parameters such as temperature, operating pressure, catalyst holdup, and superficial gas velocity affect the syngas conversion and carbon product distribution. In order to maximize the rato of different hydrocarbons products to all the products, the optimization of the operating parameters has been carried out using several optimization techniques such as genetic algorithm (GA), simulated annealing (SA), and gradient method. According to the optimization results, a high H2/CO ratio and low catalyst holdup are required to maximize naphtha, diesel, and wax products relative to the other products. On the other hand, a low H2/CO ratio and high catalyst holdup are required to maximize the olefin products relative to the other products. Moreover, high pressure has a positive impact on the all the products.

Permeability is one of the most important reservoir parameters which is very critical in the prediction and evaluation of production rate and detecting more productive reservoir intervals. This parameter is mainly measured directly from core samples. In the wells without any recovered core, in order to predict permeability, various methods are presented based on available data sets. In this study, on the basis of two different approaches, the permeability characteristics of the Upper Dalan and Lower Kangan successions are evaluated both qualitatively and quantitatively. Also, the applicability of these methods is examined. For quantitative prediction, the well-known Lucia classification scheme (1995) was evaluated and then revised based on the additional parameters, which led to more clarified petrophysical classes. Finally, the results showed that the trends of the permeability changes in the Permian-Triassic intervals were comparable with the measured values and these methods were usable in the studied intervals.

In this paper, we aim to recognize the different types of Jahrum dolomite and also to discuss the effects of dolomitization on the reservoir quality of the Jahrum formation in Bandar-Abbas region. For these purposes, we used a combination of two subsurface well sections at the Sarkhun-14 and West-Namak-01 gas-fields along with two outcrops (Finu and Khush anticlines). The lower stratigraphic intervals of the Jahrum formation were strongly altered by dolomitizing fluids. Based on petrographic observation by using polarized light, cathodoluminescence, and scanning electron microscopes, four different types of dolomite were distinguished. These data indicated that, when pervasive dolomitization occurred at the lower stratigraphic interval of Jahrum formation, this could be considered as suitable reservoir rocks and the effects of Mg-fluids on previous carbonate rocks formed abundant biomouldic porosity as a result of the dissolution of large benthic foraminifera.

The organic Rankine cycle (ORC) is a simple Rankine cycle with the use of an organic fluid instead of water. The fluid causes a heat recovery from lower temperature sources (biomass combustion, industrial waste heat, geothermal heat, solar ponds. etc.). The low temperature heat is converted into useful work that can itself be converted into electricity. An ORC contains a boiler, turbine condenser, pump, and sometimes a recuperator for improving the cycle efficiency. The focus of this study is to examine the ORC in the energy recovery of waste heat in a gas compression station with a 28 MW turbine in an area with a hot climate. The parts of a station with the enough potential are the waste heat of the exhaust gas from gas turbine. Using ORC in the heat recovery of exhaust gas is investigated in two forms of heat recovery: first, direct heat recovery in two scenarios of saturated and superheated expansion and secondly indirect heat recovery (using an oil internal cycle). The investigated working fluid is normal pentane. Produced work, thermal efficiency, Lorenz efficiency, and specific work are the parameters which are investigated related to the increase of the outlet temperature of the exhaust gas from the evaporator. The minimum temperature that the exhaust gas can be cooled down is limited due to the dew point temperature of exhaust gas and minimum approach temperature of heat exchangers. The evaluation is performed using first and second laws of thermodynamic. The first law and dew-point analysis illustrated that the exhaust gas could be cooled to 40 °C plus 80 °C for more safety. The results show that the cycle of superheated expansion scenario is more suitable for the heat recovery of the exhaust gas. From a thermodynamic point of view, using all the potential of the exhaust gas is better. Using ORC increases the efficiency of the station from 26% to 40%. In addition, in this paper, exergy analysis with the method of exergy graph is performed in order to evaluate the performance of the cycle in heat recovery. The results show that, in this case study, evaporator has the maximum and pump has the minimum influence on the system. Finally, the economic analysis of the heat recovery in superheated scenario is investigated and, for the investigated station, using an ORC system for the heat recovery of the compressed gas with high temperature is not recommended due to the low efficiency, and it is not economic.

Solar dew technology is a suitable technique for saline oily wastewater treatment using renewable solar energy. It is a good option for wastewater treatment in desert oil fields. The material which is used in this system is a non-porous hydrophilic membrane. The membrane is a non-porous and thus does not allow salts to pass; so this is a non-fouling and non-scaling membrane and there is no need for any water pretreatment. Different kinds of saline oily wastewater can be used as the influent. In this study, preparing and evaluation of membrane were considered. A membrane from Akzo Nobel Company, which is used in solar dew pilot at Sarkhoon gas refinery, was chosen as a reference. After the characterization of the membrane, it was produced by blow molding technique and then its physical and mechanical properties and vapor permeation were evaluated. Finally, the analyses of sea water and Sarkhoon gas refinery wastewater passed through the membrane were evaluated and the results were compared with the same system without a membrane. The study on physical and mechanical properties of the used membrane showed a high tensile, impact strength, and elongation. The results of the water vapor permeability of the membrane compared with porous membranes show a high performance of this membrane for using in the pervaporation system. As the membrane production is economic, it is a good candidate for using in solar dew systems.

The objective of this research was the identifying the contaminants of oil degrading bacteria.This study was conducted to isolate and identify oil-degrading bacilli. In order to increase the chances of isolating Bacillus samples were cultured on specific culture media (MSM) and was added 1% crude oil as the sole carbon source.By Culturing on blood agar, bacteria were isolated whit a beta hemolysis which produce biosurfactant. surface tension test was done. emulsification tests were performed.for selected bacteria to identify the species of bacteria was used biochemicall medium.for evaluated degradation of crude oil We used gas chromatography(GC) and spectrophotometry. Surface tension for this strain equal 35 mN / m the emulsification ability of the strains was 70%. Finally, this strain was identified as Bacillus cereus by molecular method.

The cretaceous (Albian) Burgan formation is one of the most important reservoirs in the hydrocarbon fields located in the Persian Gulf and Kuwait. In order to evaluate reservoir quality and the factors controlling reservoir properties, detailed geological (from lithological and sedimentological point of views) and reservoir studies (core analysis) have been carried out on 62.5 m of core samples from Burgan reservoir in the Foroozan field. This study shows that the Burgan formation, which mainly consists of very fine to medium-grained sandstone, claystone, carbonaceous shale, and some limited carbonate intervals, includes eight sedimentary facies deposited on a tide-dominated estuary system. These are: (1) cross-bedded channel sandstones, (2) mud flat/bay, (3) sand bar, (4) sand flat/mud flat alternation, (5) marine-influenced mud flat/shore face, (6) marine influenced sand flat/shore face, (7) restricted bay/marsh, and (8) oolitic shoal. Core porosity and permeability measurements of Burgan core plugs show that the porosity and permeability range from 3 to 36.3% and 0.6 to 13343 mD respectively. Core porosity and permeability values indicate that there is a good relationship between reservoir properties and depositional facies of the Burgan formation. Fine to medium-grained channel sandstones have the best reservoir quality, whereas shale and claystone samples belonging to mud flat to restricted bay/marsh settings have low porosity and permeability and considered as non-reservoir intervals. A comparison between core porosity/permeability values and grain size and textural parameters of the Burgan unconsolidated sands shows a good relationship between reservoir quality and grain size/sorting.

This study aims to investigate the effect of faults on the geochemical characters of the Asmari and the Bangestan reservoir oils in the Zeloi Oilfield. Plots of DBT/Ph versus Pr/Ph, C29/C27Strane20R versus Pr/Ph and Pr/(Pr) versus C27Dia/(Dia䗨) indicate that oils of these reservoirs are generated from a single source rock, comprising carbonate-marl to marine shale lithology deposited under reducing marine environment with normal salinity. Moreover, plots of various biomarker ratios such as C29Strane20S/(20S�) versus C29Straneββ/(ααββ) indicate that oils in both the Asmari and Bangestan reservoirs have a similar maturity level. In addition, the diagrams of δ13C versus Pr/Ph, Oleanan index values and the standard diagram of C28Strane percent illustrate that the source rock for these reservoirs belong to the Upper Cretaceous to Early Tertiary age. The geochemical differences between the Asmari oil of the Zeloi Oilfield and the equivalent horizons in the surrounding fields, further, supports the connection of these reservoirs. Underground Contour maps (UGC) as well as the seismic profile indicate two faults that lead to the placement of the Pabde formation against the Bangestan reservoir in this oilfield. These faults could have acted as an open conduit for the movement of the oil generated from the Pabdeh Formation into the Bangestan reservoir. Furthermore, these faults can be considered as open pathways connecting the Bangestan reservoir with the Asmari reservoir, subsequently changing their geochemical characters through mixing. This study confirms the role of faults in creating change in the geochemical properties of various horizons in Zeloi oilfield.

Ilam formation (Santonian-Campanian) is one of the major reservoirs of Bangestan group composed mainly of carbonate rocks. Facieses, depositional environment, and reservoir quality of Ilam formation in one of the oilfields in the southeast of the Persian Gulf were investigated in this study. The facies analysis indicated that the sediments of this formation had precipitated in a homoclinal and shallow carbonate ramp depositional environment. Most of sequences in the wells were studied in the field consisting of open shallow marine and restricted marine facieses. Thin layers of middle and outer ramp facieses of the deeper parts exist in some parts of sequences. Ilam formation based on the characteristics of the reservoir and facies properties can be divided into 7 reservoir layers. The upper layer is formed of rework limestone in an east-west trending channel-like structure. The other layers are A, B, C, D, E, and F; the A reservoir layer with a thickness of 35 m and a porosity of 18% is the most porous layer of Ilam formation; next placed in the order of layers are C, E, layer, channel-like facies, D, B, and F. The F layer with an average porosity of less than 5% and a permeability of less than 0.5 mD does not possess good reservoir quality. The position and orientation of the layers were determined by seismic data in the field of study.

Acidizing is one of the effective and common techniques to minimize formation damage. This method is widely used in carbonate reservoirs to increase permeability. The damaging substances are destroyed by acid and the conductive channels are created in the reservoir rocks. But, before acid injection into the reservoir rock, some tests should be carried out on reservoir rock to prevent more complex problems such as emulsion etc. In this study, tests are performed at two different concentrations of 5% and 15% normal hydrochloric acid of and magnetic hydrochloric acid. Magnetic hydrochloric acid is obtained from the dilution of concentrated hydrochloric acid with magnetic water, which is passed from a magnetic field. At a 5% concentration, due to the addition of more magnetic water to dilute hydrochloric acid, the permeability increases significantly compared to the 15% concentration of hydrochloric acid.

In this study, the effect of sol-gel method on the physicochemical properties of Ni-Cu/Al2O3-ZrO2 nanocatalyst was evaluated in comparison to sequential impregnation method. The nanocatalysts characterization was assessed by XRD, FESEM, PSD, EDS, FTIR, and TG-DTG analysis. The characterization results showed that a more uniform particle size distribution is obtained by the sol-gel method compared to the impregnation one. However, the surface area of this catalyst reduced due to the reduction of porous media and high particles density. Moreover, the sol-gel synthesis method led to the formation of very closely amorphous phases and the enhanced alkaline properties as a result of more –OH stretching vibration. Reforming of methane with CO2 was performed over Ni-Cu/Al2O3-ZrO2 at atmospheric pressure. The catalysts performance is inquired as a function of reaction temperature (550- 850 °C) and the results are reported in terms of feed conversion and syngas ratio. In the studied temperature range, it was found that the sol-gel synthesized catalyst showed a high activity. The best results were gained at 850 °C. Syngas ratio at this temperature was 0.94, which was very close to the stoichiometry ratio.

This study investigates the performance of two-fluid nozzle. The nozzle type is automatic pneumatic, which works by air pressure and flow rate and is used mainly in spray and coating systems in drug industries. Nozzle characteristics has determined by the image processing method. At first, the spray is photographed by a digital camera and then the desired images are modified and prepared for processing by MATLAB software. The results presented by means of the photography method include angle of spray. Furthermore, spray volume is calculated according to air and liquid flow rate variances. The results indicate that increasing air flow rate has a greater impact on the spray angle than increasing the liquid flow rate. Also, by changes in the ratio of air and liquid flow rate, spray angle can change. It also shows that the effect of air flow rate in the process of droplet atomization in the spray is much greater than the impact of liquid flow rate. In addition, a pneumatic two-fluid nozzle used in pharmaceutical industry and fluid bed dryers was investigated, because the spray angel and operating conditions are very important to produce the desired product.

Clay soils characteristics are completely changed in the exposure of the organic pollution, and the soil behavior determination is completely affected by some parameters such as organic pollutant type and stress history. Therefore, the soil consolidation characteristics of two kinds of clay soil with low and high plasticity have been studied. The soil samples were prepared from slurry method and slurry samples were compressed under a pre-defined load to represent the effect of stress history and different concentrations (10, 25, and 40%) of glycerol and ethanol. The results represent that the compression index (Cc) increases with increasing the concentration of the pore fluid under the slurry conditions. However, compression index decreases in samples with stress history. Although the pre-consolidation pressure increases with increasing the pollutant concentration in the low plasticity soil, the same factor is not significantly affected by pollutant concentration in the high plasticity soil. In other words, the variation of compression index is dependent on the type of the soil and the chemical composition of pore fluid.

Regarding that Iran is one of the prominent countries possessing enormous oil resources of the world, the decontamination of oil-polluted soils by a cost-effective and beneficial method such as bioremediation is of great importance. Siri Island is one of the oil producing islands of Iran that has been contaminated by oil sludge during 1980’s. Therefore, studying the role of indigenous microorganisms in the bioremediation of contaminants is very important. In this study, by the aim of the simulation of natural environment, some microcosms were prepared from clean soil of the island and they were then contaminated artificially with defined amounts of oil compounds including alkanes mix and PAH’s blend; after the addition of nitrogen and phosphate sources and water, in a six-month study period, two factors were examined: contaminants degradation rate and heterotrophic bacterial count. The results indicated that after a six-month treatment period, in alkane microcosm, C13 had the lowest remaining amount and C20 was the highest. In PHA microcosm, the biodegradation rate was directly correlated with the number of the ring of the PAH molecule, and at the end of the experiment, all types of PAH’s (except five rings molecule of Benzo(α)pyren) were completely degraded. These results completely coincided with the increase of heterotrophic bacterial count. From these results, we can conclude that indigenous bacteria of Siri Island have a high potential for the biodegradation of oil hydrocarbons. Therefore, by developing new methods for stimulating their growth, we can prepare the conditions for the effective biodegradation of the contaminants of the island.

The prediction of geomechanical parameters of a reservoir such as compressional and shear waves velocities is an important subject for the gas and oil reservoir engineers to understand the reasons of reservoir fracturing, well stability, and hydraulic fracturing process through the characterization of these elements. In the present study, we tried to predict the compressional wave velocity by a new and powerful technical method of ant colony algorithm. The results were then compared with other artificial intelligence methods. The input data of the model were selected logs of NPHI, RHOB, and Vp. To provide the model and its validity, all the data were divided into two parts: education and testing. The results revealed that ant colony algorithm had a high potential to estimate the geomechanical parameters of the reservoir, which has made considerable advances in improving data.

In this work, the corrosion inhibition performance of an environment friendly water-base acrylic terpolymer (methyl methacrylate/butyl acrylate/acrylic acid) on SAE 1018 steel in NACE standard solution containing CO2, H2S, CH3COOH, and 3.5 wt.% NaCl was investigated. Potentiodynamic polarization, electrochemical impedance spectroscopy, and optical microscopy were employed to investigate the corrosion behavior in the absence and the presence of various inhibitor concentrations in static and dynamic conditions using rotating disk electrode (RDE). The results show that blocking available anodic sites and reinforcing of the surface dielectric layers were the reasons for decreasing corrosion rate in static and dynamic conditions. The hydrodynamic condition has a positive effect on inhibitor efficiency in a way that whole efficiency values in hydrodynamic conditions are higher in comparison with the stagnant condition at an optimum concentration (0.8 mmol/l). The reason is attributed to the fact that by increasing the rotation speed, the inhibitor transfer from bulk solution to surface is enhanced. Also, it should be noted that optical microscopy examinations confirm all the results obtained by electrochemical methods. In addition, density functional theory (DFT) study shows that the oxygen atoms in monomers of the present terpolymer are suitable active sites for the adsorption of this inhibitor onto the surface. Finally, thermodynamic calculations also showed that the present inhibitor obeyed Langmuir adsorption isotherm and the absorbance on the surface is both physically and chemically.