مجله پژوهش نفت
پیاپی 86 (فروردین و اردیبهشت 1395)

A series of Pt/W-Zr-HMS catalysts with different molar ratios of Si/Zr has been prepared and modified their surface by depositing WO3. Then these catalysts were used for reforming reaction. The prepared catalysts were characterized by XRD, NH3–TPD, H2 chemisorption and nitrogen sorption techniques. The effect of various amounts of zirconium on activity and selectivity in temperature range of 200–500°C were compared. The results show that by increasing the incorporation of Zr and W into the Pt-HMS catalysts structure, the acidity of catalysts increases and the catalytic activity and selectivity for desired products (especially isomerization products) increases with decreasing Si/Zr amount (or increasing zirconium content). According to the results, these mesoporous catalysts have high activity and good selectivity for desirable products. High selectivity to desirable products especially multibranched isomers and absence of benzene are the main advantage of these catalysts. The best i-C7 selectivity, contrary to the acidic property, was observed for Pt/W-Zr(35)-HMS at T=200°C.

One of the enhanced oil recovery (EOR) methods is injecting gas or water into reservoir. Persian Gulf seawater is used for injection into Siri and Nosrat oil reservoirs. Water injection, despite the benefits, caused sedimentation. In this study, formation of sediment in mixing of formation water and injection water has been discussed. To predict sedimentation by mixing of waters, NRTL equation has been used and the relative super saturation parameter versus the percentage of seawater is plotted in different temperatures and pressures. Results showed that increasing the temperature, decreases amount of Barium sulfate sediment and increases amount of Strontium and Calcium sulfate sediment. Increasing in pressure reduces the amount of sulfate sediments. Experimental and modeling results were compared. To verify the model, results of modeling were compared with experimental results.

One of the major geochemical parameters is total organic carbon (TOC) which is used to evaluate hydrocarbon generation potential of source rocks. Measurement of such important parameter requires performing tests on small-scale drill cuttings which is too expensive and they are measured on a limited number of samples. However, petrophysical data are measured for all drilled wells in a hydrocarbon field. In this paper, the artificial neural network technology was used to estimate TOC from petrophysical logs. The correlation coefficient between the estimated TOC from neural network and measured data from Rock-Eval pyrolysis is 71% which is an acceptable value. Then, the estimated total organic carbon log is used to identify the organic facies with a maximum amount of TOC. The methodology used in this paper is cluster analysis that includes MRGC and AHC methods. The results of these two methods are compared and evaluated based on cluster validity test and the best method of data clustering was used to cluster petrophysical data into certain facies. The results showed that the MRGC clustering provides better results with higher accuracy. Moreover, using this method has advantages in comparison to AHC for determination of organic facies and has capabilities to provide high resolution clusters. The presented methodology was explained by using a case study from one well of Azadegan field, Abadan plain.

Pipelines are used to transport products mainly in the oil and gas industry. For effective operation, the pipelines must be pigged in periods of time. For a suitable performance, pigs should move at a constant velocity. It seems that the study of fluid flow around a moving pig, the pig dynamics and also, estimation of the pig movement variables is essential to control pig velocity. In this research, fluid flow around moving pig in pipeline is simulated by ANSYS CFX. At first, the force on static pig in pipeline for the different bypasses was obtained and compared with the previous study and the good agreement has been observed. Then,for mesh movement around moving pig in pipeline the remeshing method in the dynamic mesh technique was used. up and downstream distribution of pig and also velocity, acceleration and position of pig in different time are obtianed. Therefore, the Navier-Stokes equations for uncompressible viscous fluid flow are solved. The k-εturbulence model is used to simulate turbulence. In the study of pig movement through the pipe, the result showed that at first, the fluid force on pig is high and as time goes on, is reduced becouse the relative velocity between the pig and fluid flow is decreased and become equal to external force (friction force) so the net force on pig get zero. Thus, the pig acceleration is approaching to zero and the pig velocity is being constant. Also as pig goes forward the velocity and pressure through the pipe decrease because of pig acceleration reduction. So that the fluid condition becomes permanent. In the study of effect of pig on fluid velocity through the pipe, it is obvious that the most effect is on fluid velocity in pig output and in the long distance from the pig the it’s changes is low.

One of the key issues must be considered in management of reservoirs is optimal well placement. Optimal well placement is defined as a mathematical problem which maximizes an objective function such as net present value (NPV) by adjusting the well locations in an optimum place while the physical and economic constraints are considered at the same time . Modeling and simulation of reservoir is an important step in the well placement problem. The more the reservoir model is closer to the real one, the more precise the optimum well locations can be found. In most of prior suggested methods, the reservoir is modeled in Cartesian coordinate that makes the model complicated. In the present paper, a simpler reservoir model based on streamline technique is presented. Then, with the aid of the natural movement of flow in the streamline based reservoir model, we are trying to reach an effective and facile approach to solve optimal well placement problem. First, the unique and valuable information from streamlined based model is introduced. Then, this information is added to the well-known genetic optimization algorithm. With the aid of this combination, the stochastic search strategy of genetic algorithm is changed to a semi-stochastic search or based on knowledge. It is shown that the number of reservoir simulation runs is decreased and the convergence of the proposed hybrid genetic is faster than the simple genetic.

Biodegradation of starch used in drilling fluid by many microorganisms¡ result in reduction of starch concentration in the fluid which leads to fluid efficiency downfall. Present study has been done with the aim of identification of major starch degrading bacteria in the drilling fluid and manner of controling the growth and activity of these organisms. Bacteria peresent in back up drilling fluid¡were isolated and amylase activity was studied by starch hydrolysis test. Strain with most starch hydrolysis ability in all three temperatures (37¡ 45 and 55°C) were selected as superior strain and was identified by 16S rRNA. Also growth curve of superior strain was plotted. 54 bacterial strains include 26 Gram-positive bacillus¡ 22 Gram-negative bacillus and 6 Gram-positive cocci was isolated. 18 strains from 26 Gram-positive bacillus was sporated. Three strains in all three temperatures(37¡ 45 and 55°C) had growth and significant amylase activity. Bacteria with the ability to create maximum clear halo zone of amylase were selected as superior strain. The results of 16S rRNA analysis showed 99.8% similarity of superior strain to Bacillus licheniformis. Sporated Gram-positive bacillus belongs to Bacillus jenus like Bacillus licheniformis isolataed in this study was the most active degrading bacteria in well special conditions. Identification of degradation factors with the aim of selection of a suitable biocide in order to prevent biodegredeation is recommended.

The purpose of this study is to calculate and investigate the effect of porosity on the elastic moduli in Kangan and Dalan Formations in the South Pars gas field of Iran. Compressional and shear wave velocities were calculated using travel times of compressional wave and travel times of shear waves, which are deduced from the Dipole Shear Sonic Imager (DSI) logs. Bulk modulus, Shear modulus, Young’s modulus, Lame parameter, Poisson’s ratio and the ratio of K/G were calculated using the relationship between the acoustic wave velocities, density and physical moduli. In this study, the relationship between porosity and elastic moduli were determined by real data and observed that elastic moduli are decreased by porosity increasing. Comparison of elastic moduli with porosity shows significant consistency between bulk modulus and porosity (compared to other moduli). Also, the ratios of Vp/Vs, K/G and Poisson’s ratio were examined. Result of this investigation showed that these ratios are slightly reduced by increasing the porosity.

Asmari Formation (Oligocene-Miocene) is one of the most important reservoir in the Aghajari oil field in the Dezful Embayment in south west of Iran which is composed of limestone, dolomite and sandstone units. The purpose of this study is to identify, differentiate and interpret the diagenetic processes and their impact on the reservoir quality of the Asmari Formation in wells 64, 30 and 149 of Aghajari oil field. The most important diagenetic processes that affected the Asmari Formation include dissolution, compaction, fracturing, dolomitization, cementation and anhydritization. Processes such as dissolution (by creating vuggy and moldic porosity), fracturing and dolomitization increase the reservoir quality while and processes such as anhydritization, compaction and cementation reduced the reservoir quality in zone of 3 and 4. Also one of the reasons for increasing the reservoir quality of Asmari Formation is the present of sandstone units in the Dezful Embayment. These increases in reservoir quality can be related to sorting and rounding of grain size, geometry and distribution of sandstone in this oil field. These processes led to creation of the best reservoir quality in quartzarenite and limy sandstones facies. Finally, zone 3 has a better reservoir quality than zone 4 that it is due to impact of diagenetic processes as well as increases sandstones thickness.

Although there have been several models for predicting the asphaltene-induced permeability reduction, the present study investigates the hydrodynamic effects of asphaltene deposition in the porous media with a novel and partially analytical approach. In order to find the amount of permeability reduction, we have modeled the variations of hydraulic radius. The main idea for modeling the permeability reduction is the fact that by deposition of the particles, the available void space is reduced. Also, the drag force between the particles and the fluid reduces the flow potential. In this paper, using the size variation of the asphaltene particles during flocculation, with assuming that the size distribution is equal inside and outside the porous medium, permeability reduction is obtained and matches with the existing experimental results. Modeling is done using MATLAB and a code is written for calculating the permeability reduction due to formation damage. This model is partially analytical and do not use numerical estimations, thus it is flexible to be applied for other formation damage problems. In addition, this modeling can predict the deposition process if the changes of the particle size distribution is known as a function of time.

The main objective of this study is to investigate the potential of cyanobacterium Fischerella ambigua ISC67ý in the biodegradation of crude oil and evaluation of oil effect on physiological responses. In this experimental study, the cyanobacterium Fischerella ambigua ý ISC67 was obtained from the algal ýculture collection. The growth rate of cyanobacteria in 1% treatment and control sample of crude oil measured at ýý750 nm and chlorophyll content in 0.5, 1, 2, and 4% treatments of crude oil measured at h nm ýý665nm wavelength using a spectrophotometer. For measuring of dry weight, firstlyý using weighed ýfilter paper cyanobacteria were isolated from the culture medium and their weights were measured ýafter drying. ýThe rate of biodegradation of crude oil analyzed by gas chromatography. The results showed that the growth of this ýcyanobacterium in the presence of crude oil is almost same as of control sample.ý So that these growth rates are nearly equal and sometimes lower than the control sample. Also, with increasing concentrations of crude oil, dry weight of this cyanobacterium in 0.5% and 2% treatments increased compared to the control sample and it chlorophyll rate in the various treatments of crude is reduced The average of petroleum hydrocarbon biodegradation in 14 days of treatment compared to the control sample was at a rate of 42.32 % and and 28 days was 54.21% respectively. In this study it was found that cyanobacterium Fischerella ambigua ISC67ý has great potential in biodegradation of crude oil. Therefore, these results indicate the potential of this cyanobacterium for its use as an indicator to eliminate pollution in contaminated areas.

To study of petroleum reservoirs which their productions are function of their fractured system, fractures assessment is necessary and important in oil production optimization and field development. The purpose of this research is recognition of a quick method for identification of fractured zones using petrophysical logs which are handy in all wells, and their effects on porosity and permeability of Asmari reservoir of Balarood oil field. The result shows that although some factors such as lithology and reservoir fluids effects on petrophysical logs, requiring minor corrections to logs by means of mathematical methods such as derivation can be used to determine fractured zones on logs, which show great consistency with image logs and velocity deviation log. Results show that zones of abundant bearing fractures can be easily recognized on first stage of derivation on petrophysical logs. Derivation process of any log is defined as a function for that log. Tectonic information and geological prospective of oil field will have an apparent contribution in identification of fractured zones. In addition, fractures and porous zones have had effective impact on the reservoir rock properties. The results indicated that the production in the Asmari reservoir of this field is a combination of fractures and rock matrix and fracture analysis can be done by using petrophysical logs in old drilled wells without image logs as well. As six logs RHOB, NPHI, GR, DT, PEF, CAL have vital role in petrophysical studies, these six tools are the best logs to diagnosis of fractured zones due to their responses against the fracture along with doing some corrections in these logs.

The physiochemical techniques presently available for treatment of H2S containing gases are many and various. The gas processing industry is seeking novel, cost effective, environmentally compatible and operator friendly technologies applicable to the small volume producers. So in near future, smaller gas reservoirs with high concentration of H2S will be explored. The widespread research for finding more economical methods has led to investigate microbiological processes. The biological process which has been studied in this article is Bio-SR process. The Bio-SR process uses Thiobacillus ferrooxidans bacteria to recover solution used in sweetening sour gas. In this study, an indigenous Thiobacillus ferrooxidans has been isolated from Sarcheshme copper mine and the effects of process variables on the growth and activity of this bacteria were investigated in shake flask. Then some experiments have also been done, using bubble column and fixed bed bioreactor. The results showed that the isolated bacteria has very high ability for oxidation of Iron (II) and recovering of solution that used in sweetening sour gas. In this study, maximum rate of biological oxidation were 1.2 and 0.9 gr/lit.hr in Erlenmeyer Hask and bubble column bioreactor respectively which were two and three times more than previous study.

Improving the properties of asphalt mixtures has been one of the most vital issues in pavement engineering. One of the most important additives in improving asphalt condition is Polypropylene Fiber. This additive is used in civil engineering and pavement engineering in order to enhancing the physical and mechanical properties of asphalt mixtures. In this research by adding 0.1 to 0.5 contents of polypropylene fiber to asphalt specimen of binder grading based on complex procedure and performing Indirect Tensile Test, Resilient Modulus test and Dynamical Creep test and data analyzing, observed that increasing of this modifier leads to decreasing the dry tensile strength, wet tensile strength, Resilient Modulus and Flow number. Results showed that polypropylene fiber weakens of asphalt against moisture and decreases the rutting potential of asphalt specimen and regards to absorbing to aggregates and bitumen, it leads to weakening the cohesion of aggregates. Because of decreasing the flow number, this modifier causes less forming of asphalt mixtures, too.

Total organic carbon is among the most important geochemical factors for source rock assessment. Considering the general scarcity of measured total organic carbon data in exploration area together with expensive and time consuming procedure of Rock-Eval pyrolysis, development of a new method for direct estimation of TOC parameter from well log and seismic data is an important issue and the object of this study. In this paper, 2D seismic data and petrophysical data of the Pabdeh Formation from 4 wells of the Mansuri Oil field are used. Also ΔLog R was used to predict TOC values from petrophysical data. The calculated values were used as inputs for a Multi Attribute Analysis to find a logical relation with seismic attributes. In this study, seismic inversion was performed based on Neural Networks Algorithm and the resulting acoustic impedance was utilized as an external attribute. Afterwards, a probabilistic neural network was trained using a set of predicting attributes derived from multiple regression. Subsequently, TOC was estimated by using seismic attributes with correlation coefficient of 75%. In the next step of study, the nonlinear Ant Colony Optimization technique was utilized as an intelligent tool to estimate and production TOC seismic section from seismic attributes. Nonlinear Ant Colony calculates weight factors for each of seismic attributes. Finally, having these weights and seismic attributes, TOC seismic section was produced.

The particle size distribution (PSD) is one of the most important parameters of emulsion polymerization latexes. This parameter affected the rheological and optical properties, adhesion, film formation and mechanical strength of latexes. Therefore, the modeling of PSD is of utmost importance in terms of application and mechanistic studies. Dynamic evolution of PSD is described by a set of population balance equations which involved various phenomena such as nucleation, growth, and coagulation. The extensive application and especially annually massive production of poly(butylacrylate) and polybutadiene produced by emulsion polymerization, highlights the significant of modeling these processes, which could resulted in better mechanistic knowledge and tailor-made polymer materials. In this paper, a mechanistic model based on population balance equations is developed for butyl acrylate and butadiene emulsion polymerization in a batch reactor. This model is used to predict the evolution of particle size distribution and the finite volume method as a precise technique is used for discritizing PBEs. The simulation results compared with the measured values during the evolution of conversion and average particle diameter for different initial surfactant concentrations.

Surfactant flooding is known as an essential and important method for enhancing oil recovery from carbonate reservoirs. High amount of Adsorption of some surfactants onto carbonated surfaces makes some difficulties in accurate prediction of oil recovery efficiency in this type of injection process. In this paper, the adsorption of nonionic surfactant Triton x-100 on the surface of the carbonate rock is experimented. The carbonate rock is crushed and contacted with surfactant solution, and the amount of the surfactant adsorption on the surface of the carbonate rock is measured after arriving the equilibrium condition. It is observed that the adsorption of the surfactant is saturated at about 500 ppm. Also, the adsorption results matched well with the Langmuir model. The amount of Langmuir constant is obtained 173.34 gr sol / gr surf and the maximum adsorption is obtained 19.23 mg surf /gr rock. Comparing the adsorption data shows that the amount of surfactant adsorption and its variations especially above the critical micelle concentration in carbonate rocks is greater than sandstones. So, it is more important to consider the surfactant adsorption and its waste during surfactant injection and its simulations in carbonate reservoirs.