مجله پژوهش نفت
پیاپی 82 (امرداد و شهریور 1394)

The catalytic dehydrogenation of propane as an initial material in propylene production is very important. The application of Pt-Sn/γ-Al2O3 as a industrial catalyst in dehydrogenation process of propane has shown to be very active and selective. Using membrane reactors is the suitable method for solving the thermodynamic limitation of this process. In this study, the dehydrogenation of propane has been investigated by using a membrane reactor. This study is based on two parts; first the manufacturing of membrane and its structure are investigated and, in the other section, the application of membrane to dehydrogenation is studied. The investigation of membrane surface morphology and XRD show the existence of a Pd-Ag homogeneous phase. The effects of different parameters such as temperature, He/propane ratio, and propane flow on conversion and propene selectivity have been investigated. This reaction has been performed with and without a membrane. The results show that the application of membrane increases the conversion from a range of 19.78-43.24 to 21-47.13 and raises the selectivity from 41.36-79.86 to 50.71-89.44.

In hydrocarbon reservoirs (especially in carbonate rocks)، the variation of pore type and size is influenced by diagenesis effects. Hence pore type distribution and capillary pressure in the reservoir rock is the main factor controlling fluid flow in porous media. In other words، the determination of pore type/size and capillary pressure has an important role in understanding petrophysical features، optimizing the number of wells in the field، and forecasting the recoverable hydrocarbon. In this paper، pore types in the mixed carbonate-siliciclastic Asmari formation is divided by velocity deviation log into three classes (positive، zero، and negative deviation) and eight subclasses. Six subclasses are related to carbonate part (interaparticle or interafossil، moldic or vuggy، microporosity، interparticle، intercrystalline، and fracture) and two subclasses are related to clastic part (intergranular and shale microporosity). After identifying pore types، pore size and pseudo capillary pressure are continuously determined in each subclasses throughout the well bore by using NMR log. Pore size and pseudo capillary pressure are compared by mercury injection capillary pressure curves. The results of this study show that intergranular porosity is the main factor for production in calstic intervals; however، fracture، interparticle، and intercrystalline porosities play an important role in carbonate intervals. The distributions of each four pore types are continuously determined along the well bore.

These days, hydrocarbon resources are one of the most important human needs. Therefore, it is necessary to use methods with high efficiency and low costs. Due to direct underground accessing, drilling is the most efficient method for subsurface studies. However, because of high cost and imperfect covering of the area under study, it is required to employ methods which provide better results. Seismography is one of the methods for collecting surface data, which exhibits an efficient model of reservoir characteristics. Seismic inversion is the method which enhances the resolution and accuracy of reservoir model by compiling seismic and well logging data. Impedance acoustic model results from inversion and indicates the variability of layers or fluid content. In this study, an impedance model was obtained using various inversion procedures, and porosity was then calculated. These procedures are post stack. Seismic, well logging data, and interpreted horizons were merged in Hendijan and Behregansar oil fields in the Persian Gulf. Seismic inversion was performed by band limited, sparse spike, and model based methods in Jahrom formation at a depth of about 2200m and a thickness of 300m. Finally, by comparison of the results, the model based method was introduced as the best one, because of the high correlation coefficient (99.65%) and low error (0.08)

Fahliyan limestone formation belongs to the Khami group, one of the oil and gas reservoir rocks in the southwest of Iran. This study is divided in two parts; in the first part, the reservoir characteristics of Fahliyan formation were evaluated in the well studied by taking into account the conditions of falling and gas effect on reading charts. Accordingly, lithology, by using neutron-density and M-N plots, was diagnosed to be limestone plus some mineral dolomite; the average of petrophysical parameters including effective porosity (PHIE), effective water saturation (SWE), and hydrocarbons in flashed zone and virgin zone were calculated to be 2.1, 56, 0.4, and 1.1% respectively. The pay zones and the average of petrophysical parameters in these zones by determining cut-offs for the two parameters of effective porosity (PHIE >= 2.2) and effective water saturation (SWE<= 55) were calculated. In the second part, the reservoir facies and non-reservoir facies were grouped by MRGC method and the sequence was partitioned into two reservoir and non-reservoir facies; the average of petrophysical parameters was compared between the two facies. There was good agreement between the specified reservoir facies and production zones in the total sequence evaluated. Finally, the reservoir main parts were identified for extracting gas and reservoir zoning was carried out in the interval studied.

With increasing the world population, domestic economies, and living standards, the demand for traditional fossil fuels has been increased worldwide, especially for the natural gas. Therefore, with the waning of conventional hydrocarbon reservoir, the exploration and production of unconventional reservoirs including gas from coal is increasingly becoming economical. Due to the vast existence of coal deposits in Upper Triassic-Middle Jurassic deposits (Shemshak Group) in Iran, which extends from the north to the centre and the east of the country, the study and evaluation of these unconventional gas reservoirs become necessary. In order to evaluate the initial volume of the produced and absorbed gas in coal reservoirs, Galandrud area in the Central Alborz was a subject of this study. To accomplish this, detailed analyses including pyrolysis, proximate, and organic petrography on the coal samples were carried out. Based on the experimental results and by using empirical formulas, the volumes of the produced and absorbed gas in the coal layers were calculated. Organic petrography showed that the coal was humic compound (kerogen type III) and vitrinite maceral was the dominant constituent which represented catagenesis degree of thermal maturation (Ro=0.6 to 0.8%) suggesting high volatile bituminous capable of producing methane hydrocarbon. The calculation based on empirical formulas showed that the amount of the produced gas per ton of coal was 5.22 cubic meters and the absorbed volume was about 0.89 cubic meters per ton of coal on average. According to the total storage volume of coal in Galandrud area, the amount of the produced methane is about 319 million cubic meters and gas in place in the coal seams in this area reaches more than 52 million cubic meters.

One of the most important issues in EOR is asphaltene deposition. Asphaltene is partly dissolved in oil, partly in steric-colloidal form and partly in micellar form depending on the composition of crude oil. Adding dispersing agents to oil, which are functionally similar to natural resin, prevents the aggregation of asphaltenes in crude oil. Inhibition strength is a capability of the inhibitor to delay formation of asphaltene flocculates, which depends on the interaction between the inhibitor and asphaltene particles. In this study, the onset of asphaltene precipitation was evaluated using a viscometric method in the presence of three types of inhibitors. In order to determine stabilization (dispersion) strength, the context of “effective adsorption point” of inhibitor is introduced by the use of the shear effects of asphaltene aggregates. The results showed that the inhibitor was adsorbed on asphaltene micelles and the stabilization strength increased with increasing inhibitor concentration. The comparison between colloidal instability index (CII) and the stabilization strength of the inhibitor indicated that the inhibition and stabilization strengths of the studied inhibitors were much higher than the natural resins.

In reservoir management, the key goal is to reach the maximum economic profit. This can be achieved by the evaluation of economic parameters. One of the main factors in the economic evaluation and capital expenditure of any filed development is the number of wells necessary to reach the optimum hydrocarbon production from the reservoir. In this paper, an attempt has been made to select the optimum number of wells in one of the Iran southwest carbonate reservoirs. Uncertainty analysis has been carried out using MonteCarlo and Genetic Algorithm techniques. Both horizontal and vertical wells were analyzed, and the number of scenarios were performed to select the optimum number of wells. The best scenarios from an economic point of view were selected for field development.

Fischer-Tropsch synthesis provides an alternative route for the production of clean transportation fuels and high molecular weight hydrocarbons via catalyzed CO hydrogenation. In this paper, three nanocatalysts including iron, copper, potassium, and lanthanium were prepared using a microemulsion method. The composition of the final catalysts, in terms of the atomic ratio of the elements, was selected as 100Fe/4Cu/2K, 100Fe/4Cu/2La, and 100Fe/4Cu/1K/1La. XRD, BET, TEM, and TPR techniques were employed for the investigation of phase, structure, and morphology properties and the reduction in temperature. Fischer-Tropsch synthesis reaction was performed in a fixed bed reactor at a pressure of 18 atm, a temperature of 290 °C, an H2/CO ratio of 1, and a GHSV equal to 3 NL.h-1.gCat-1. The results show that the reaction activities of Fischer-Tropsch synthesis and water-gas shift are higher in the case of using two promoters compared to when only one promoter is employed. Methane selectivity dropped to about 10.8%, while CO conversion increased to around 86.9%, when two promoters were used.

The Jahrum formation is one of the most important reservoirs in the Zagros basin. In this research, the Jahrum formation in west and northwest Bandar Abbas area has been investigated. The thickness of this formation in the studied area in Anguru Section is about 341m, of which, based on paleontological studies, 167m belong to Lower and Middle Eocene and 174m is assigned to Late Eocene. The lower contact of this formation with the Pabdeh formation is gradational and the upper contact with the Asmari formation is paraconformable. The Jahrum formation in the studied section is lithologically consists of fossiliferous limestone and medium to thick layer beige to gray dolomitic limestone. Based on the field and petrographic studies, 6 types of microfacies and 6 subfacies have been identified in the studied interval of the Jahrum formation. These microfacies have been deposited in 3 standard facies belt, including lagoon, Nummulites Bank, and open marine environment. These microfacies have been deposited in a distally steepened ramp.

In this study, a new method is developed to estimate the fracture parameters in fractured reservoirs. This method is used to interpret incomplete well test data and is applicable to both drawdown and buildup tests. Using this method, the value of λ/ω ratio can be estimated for the drawdown test when the first straight line and an early transition zone are solely observed in the test data. Hence, there is no need to observe the inflection point in the semi-log plot of the pressure data. For buildup test, however, the technique can be combined with previously published approaches to estimate separate values of λ and ω. The main assumption behind the new technique is employing the dual porosity model with pseudo-steady state interporosity flow to obtain the final solution; the final equation is achieved by approximating the pressure derivative data using the Taylor series. The permeability of the rock matrix can be estimated through new developed technique provided that sufficient fluid and rock data are available. For validation purposes, three different well test cases (two drawdown and one buildup) have been simulated using the Pansystem software. Moreover, a field case, adopted from the open literature, is used to test the accuracy of the developed technique over actual field data. The results revealed that the value of λ/ω estimated through the new technique has an insignificant difference with the input λ/ω values for simulation purposes.

Nanotechnology is of significant importance in many scientific fields. In view of engineering problems, nanomaterials have found wide practical applications. In this work, iron oxide nanoparticles called maghemite (γ-Fe2O3) were synthesized. The synthesized nanoparticles were used to adsorb asphaltene from prepared asphaltene-toluene solutions. Asphaltene adsorption kinetic behavior was modeled using experimental data. For the synthesis of maghemite nanoparticles, the co-precipitation of ferric and ferrous ions method as a simple and inexpensive method was selected. The crystalline structure and morphology of synthesized maghemite was investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. The nanoparticles were also characterized by using FT-IR spectrum. The results of these analyses showed that the γ-Fe2O3 nanoparticles had a crystalline structure with a size smaller than 50 nm and were spherical in shape. The maghemite nanoparticles were used for the adsorption of asphaltenes. The results obtained from adsorption kinetics analysis showed that asphaltene was rapidly adsorbed onto γ-Fe2O3 nanoparticles, and equilibrium was achieved in less than 2 hrs. The Lagergren pseudo-first-order and the pseudo-second-order models were employed for determination of the adsorption kinetics. It was found that the kinetic results were in good agreement with the pseudo-second-order model.

From a regional-scale or quick assessment viewpoint, a number of reservoir researchers provided heuristic methodologies to handle the initial technical evaluation of oil reservoirs for carbon dioxide flooding. But, they have not utilized a methodology among multi-attribute decision making approaches, which are more widely accepted and commonly applied. Therefore, this paper aims to introduce the use of a common multi-attribute decision making method, Grey Relational Analysis, for solving the problem of initial technical ranking of oil reservoirs for CO2-flooding EOR. Moreover, the proposed methodology makes some significance to the field of Grey Relational Analysis. The proposed procedure enables oil industry decision makers to consider the parametric uncertainty inherent in the problem by utilizing grey numbers. Furthermore, it serves as a more comprehensive procedure for analyzing real case problems, in which considering different types of criteria seems essential. The methodology is applied to a real case study of Iranian oil reservoirs in order to obtain illustrative results.

One of the important geochemical parameters used to evaluate the hydrocarbon potential of source rock is total organic carbon (TOC). TOC measurement is time-consuming and rather expensive and considerable number of drill hole samples including core or cuttings have to be analyzed. In this study, TOC values were estimated initially using petrophysical logs generally available from drilled wells. For this purpose, an ant colony system was used based on hierarchical clustering analysis. The first stage was comprised of hierarchical clustering and the second stage included ant colony system, which was designed continuously with a normal probability distribution function. Continuous ant colony system (CACS) calculated weight coefficients of nonlinear proposed function for the petrophysical data of each cluster. The results show that this algorithm has a successful performance in combination with clustering for the estimation of TOC log. Using these coefficients and petrophysical data, TOC log can be generated for other wells in this field. This study is based on the data collected from three wells of the Ahwaz oilfields and can be generalized to other developmental wells.

In this study, at first, by using the experimental vapor pressure and saturated liquid volume of N-formyl morpholine, the parameters of cubic plus association (CPA) equation of state for NFM are evaluated. In this work, five association schemes (1A, 2A, 3B, 4B, and 4C) are used for NFM and the parameters of CPA equation of state are evaluated for these association schemes. Then, bubble point calculation is used for vapor-liquid equilibrium calculation in these mixtures. For this purpose, aromatics were considered as two types; in the first type, aromatics cannot cross associate with NFM and in the second type aromatics can cross association with NFM. Binary interaction parameters between aromatics and NFM were obtained and the modeling results were compared to experimental data and the best association scheme for NFM was obtained. The results show that 4C and 4B association schemes give the best results for correlating vapor-liquid equilibrium of mixtures containing aromatics and NFM.

The exhaust emission pollutants of diesel engines include particulate matters (PM), smoke, oxides of nitrogen (NOx), and other harmful compounds. Ethanol diesel blend (e-diesel) is a clean-burning alternative to regular diesel fuel. The easiest method by which ethanol can be used is in the form of solutions, but ethanol has limited solubility in diesel. The problem of limited solubility has been overcome by emulsions. In this paper, with the use of environmentally friendly additives, the preparation of stable and clear nanoemulsions is investigated. The comparison of engine performance of ethanol-diesel emulsions and standard diesel in OM314 engine showed a reduction of 7.5% and 17.2% in power and smoke respectively. The use of ethanol-diesel fuels had no detrimental effect on the fuel system and engine components of OM314 engine.

With the increase of carbon dioxide concentration in the atmosphere, the quick emission reduction methods, i.e. carbon capture and storage/enhanced hydrocarbon recovery (CCS/EHR), have been introduced in recent years. While using CO2 for enhancing the recovery of oil reservoirs has been the subject of several studies in the past decades, it has not been fully studied in the gas reservoirs, mainly because of high recovery factor of gas reservoirs and mixing of the reservoir gas and CO2. In this work, the process of carbon capture and storage/enhanced gas recovery (CCS/EGR) in one of the south Iran gas reservoirs was studied. After the sensitivity analyses of different parameters with an optimum design of experiments (DOE) method the significant parameter was selected and optimized using genetic algorithm (GA) considering the net present value (NPV) as the objective function. This study shows that in addition to the production of residual reservoir gas, injecting CO2 in the gas reservoirs under optimized conditions (appropriate injection pattern and operational condition and pure CO2 injection) results in the storage of considerable amount of CO2, and thereby preventing it from being emitted in the atmosphere. Therefore, as the gas reservoir recovery and revenues of clean development mechanism (CDM) increase, the process of CCS/EGR becomes economically and environmentally profitable.