مجله پژوهش نفت
پیاپی 99 (خرداد و تیر 1397)

Water production is one of the big challenges of oil and gas recovery. This excessive water production is a significant operational, economic and environmental problem. One of the main causes of water production is an improper water injection plan. Thus, the waterflood projects should be managed in a manner to delay the water breakthrough in producers as much as possible, and as a result improves sweep efficiency and increases the oil recovery. One of the proposed new approaches to an efficient waterflood project is the Water Allocation Management (WAM). Water allocation management aims to inject the water in a manner that increases the total oil recovery for a given volume of water. The good injectors are thus those which support the good producers. Inter-Well Connectivity of producers and injectors is an important parameter that affects the efficiency of allocation management in waterflood projects. Inter-well connectivity determines how effectively injection and production wells are connected to each other. One of the methods recently employed by petroleum engineers to measure this parameter is the Capacitance-Resistance Model (CRM). CRM assumes the reservoir as a system which gets an input signal (injection rate) and responses by an output signal (production rate). By analyzing these behaviors, a series of equations are written to correlate the output and input signals. In these equations, there are two main unknown parameters. The first one is the time constants and the second is the weight factors (well connectivity parameters). These parameters can be determined by history-matching the production/injection rates. After finding the unknown parameters, by employing the weight factors and the water cut from production wells, a new analytical algorithm is presented to calculate the allocated factor for each injection wells to improve waterflooding in order to increase the cumulative oil production and reduce the cumulative water production.

Ultrasound assisted oxidative desulfurization (UAOD) is a new process for the sulfur removal from different middle distillate cuts. In the UAOD process, at first, the sulfur-containing compounds are oxidized using a suitable oxidation system under ultrasound irradiation. Then, the oxidized sulfur-containing compounds are separated by solvent extraction. In the present study, the effect of interfacial tension between aqueous and hydrocarbon phases on the sulfur removal of diesel fuel has been investigated for the first time. The selected oxidation system was hydrogen peroxide/formic acid system. In this regards, three different surfactants including anionic, cationic, and nonionic surfactants have been evaluated. The results revealed that the application of sodium dodecyl sulfate (SDS) as an anionic surfactant and cetyltrimethylammonium bromide (CTAB) as a cationic surfactant leads to the sulfur removal of 82.65 and 83.10% after oxidation followed by solvent extraction respectively. The sulfur removal in the absence of surfactants was 81.61% in the same oxidation and extraction conditions. The application of span 60 as a nonionic surfactant leads to a decrease in sulfur removal to 78.65% in the same oxidation and extraction conditions. However, the application of span 60 leads to about 3% increase in the sulfur removal in comparison with the case without surfactant after the oxidation step. Therefore, the addition of surfactants can lead to a positive effect on the oxidation step due to decreasing the interfacial tension between aqueous and hydrocarbon phases and a negative effect on the extraction step of the UAOD process.

In this paper, a setup for performing dynamic flow experiments was prepared. A set of natural depletion tests were done to investigate the effects of pressure depletion and the initial asphaltene content of crude oils on asphaltene deposition in porous media using two live oil samples of Iranain reservoirs. The results of these experiments, which were done in constant rate and three pressure steps, show that the asphaltene deposition occurs by decreasing pressure in the vicinity of bubble point pressure and the main mechanisms are surface deposition, pore throat plugging and in some period the entrainment of the particles via the flow of oil is observed. According to the experiments, in case of the oils with less asphaltene content, the dominant mechanism is surface deposition, and the rate of deposition is uniform, while using the crude oil with higher asphaltene content, the pore throat plugging mechanism has more important role in the permeability reduction of reservoir rock.

In the present work, the obtained results are presented for aromatic hydrocarbons producing by gamma alumina and H-Beta zeolite as catalysts. Gamma alumina is placed at the entrance zone of a Vertical fixed bed reactor with up to down flow stream in order to convert methanol to dimethyl ether, and H-beta zeolite is loaded at follows for converting dimethyl ether to aromatic hydrocarbons. Both catalysts have sizes between 1 and 2 millimeter and the same weight ratio. The weight of each catalysts in the reactor is 2 grams. Silica to alumina ratio and specific surface area of H-beta are 7.9 and 500 m2/g respectively. Also, the specific surface area of the used gamma alumina is 192 m2/g. Experiments were done at 250 up to 370 oC. The desired space velocity (WHSV) for H-Beta at 370 oC was 7.11h1-. According to Gc-Mass analysis on the reactor products, the main component at the above mentioned conditions was Hexa-methyl Benzene. Formation of this component was satisfied by IR-spectroscopy and C-NMR and H-NMR analysis. Addition to hexa-methyl benzene, the analysis confirmed that some other components such as tri ethyl benzene, ethyl penta-methyl benzene and dimethy ethyl benzene were formed by the reaction.

There are several Jurassic and Cretaceous hydrocarbon source rocks in the Abadan Plain, including the organic-rich Albian Kazhdumi Formation which has a favorable geochemical characteristics for oil and gas generation. In this study, basin modeling used to investigate and compare petroleum generation from the Kazhdumi Formation of a well drilled on the Darquain anticline as well as a hypothetical constructed well for the deepest part of the kitchen area. The thermal history of the studied wells reconstructed using the basin modeling software and oil generation stage of the source rock were obtained. Modeling results have been investigated and differences in the history of the oil production processes in the drilled well and the deep part of the kitchen area are discussed. Results showed that temperature, maturity, transformation ratio, and hydrocarbon expulsion quantity increase from the anticline toward the hypothetical well. However, In the geological past, however, Kazhdumi temperature and maturity in the hypothetical well were less than anticline position. In the drilled well, hydrocarbon expulsion from Kazhdumi occurred from 20 Ma, and it is not reach to peak of oil generation stage. This source rock passed peak of oil generation in the hypothetical well area where the hydrocarbon expulsion occurred from 10 Ma, and expulsion quantity was about 75 percent more than anticline.

The use of carbon steel is conventional for the transmission and distribution of treated natural gas. In order to control the internal corrosion of the gas transfer pipelines, the moisture content is removed in dehydration unit. In addition, the amount of CO2 gas is limited to less than 2%. In this study, the cause of the failure of an 8-inch gas distribution pipeline is investigated. The pipeline was not in service for two years and then it was in operation for 6 years before the failure. Microscopic examinations, as well as chemical analyzes such as EDS and XRD, were used to determine the possible mechanisms of damage. In addition, the NORSOK CO2 corrosion model was used to determine the corrosion rate in operating conditions. The results showed that corrosion caused by carbon dioxide is the most likely cause of internal corrosion of the pipeline and the occurrence of the leakage.

Hydraulic fracturing is one of the conventional and common methods to stimulate oil and gas formations with low permeability. This method is widely used for creating artificial fractures and stimulate fluid flow in oil and gas wells. In this paper, fracture propagation process was simulated by using a Discrete Fracture Network (DFN) in UDEC software. Discrete Element Method (DEM) is a key for simulating hydraulic fracturing which is capable of performing a fully coupled hydromechanical analysis to model fluid flow through a network of fractures. In this regard, fictitious joints were used for modeling fracture propagation in a medium with equal to intact rock properties. To achieve this goal, the mechanical and strength properties of discontinuities were considered equal to mechanical and strength properties of intact rock. Then, the role of rock mechanics parameters including elastic modulus, cohesion and friction angle were studied in the process of fracture propagation. The results of numerical simulations showed that the extended fracture length is increased by increasing the elastic modulus and decreasing the friction angle. Also, increasing in the cohesion does not have a significant effect on the extended fracture length, but it reduces the hydraulic fracture opening.

In this paper, the effect of mesoporous increasing on activity high silica ZSM-5zeolite in methanol conversion to olefins investigated. Therefore, for forming the mesoporous, desiliction method with Sodium Hydroxide, tetrapropylammonium hydroxide and cetyltrimethylammonium bromide materials are used. The samples were characterized by XRD, FESEM, N2 Adsorption/Desorption and NH3-TPD techniques. The XRD results indicated that using Tetrapropylammonium hydroxide in desilication process by Sodium Hydroxide (in meso pore Na-TPA sample) caused high crystallinity preservation for Ref-ZSM-5 zeolite. FESEM images for this sample showed cracks and small holes on the surface of crystals. The N2 Adsorption/Desorption results confirmed an increase in the meso pore volume and meso surface area in Na-TPA sample compare to Ref-ZSM-5 zeolite. These new mesoporous, with increasing access to active sites in framework, caused improvement on the catalytic performance. Performing the reactor test on catalyst in same reaction condition showed that this catalyst with methanol conversion higher than 90% in 41 days had acceptable stability. During this time, average of propylene selectivity, total olefins selectivity and propylene to ethylene ratio were 43%, 76% and 6% respectively. While the desilicated sample with Sodium Hydroxide and cetyltrimethylammonium bromide showed complete change from Ref-ZSM-5zeolite to mesoporous Al-MCM-41molecular sieves. This molecular sieves with completely mesoporous structure and, acid sites with low strength did not show activity in the methanol to olefin reaction.

Oily wastewater is important environmental pollution which leads to irreparable damages to the environment. Ultrafiltration process is considered as a commonly used process is oily wastewater process. In the current study, two types of (AC/TiO2) dynamic membranes (pre-coated and self-forming dynamic membrane) was used for oily wastewater treatment to decrease fouling of ultrafiltration membrane. The pre-coated dynamic membrane decreased fouling of the of ultrafiltration membrane while the self-forming membrane intensified the membrane fouling after three cycles of filtration. The COD rejection rate obtained for self-forming dynamic membrane was 45% that is more than the pre-coated dynamic membrane and polymeric membrane, this result shows high separation efficiency for this membrane. The obtained result showed that the pre-coated (AC/TiO2) dynamic membrane can be considered as a good candidate to control the fouling effect of ultrafiltration membrane in oily wastewater treatment.

In recent years, several studies have been conducted regarding wettability alteration in petroleum reservoir rock using hydrophilic Silica (SiO2), Alumina (Al2O3) and Titania (TiO2) nanoparticles in order to improve waterflooding process that results in enhanced oil recovery (EOR). The studies have showed the significant role of these nanoparticles; however, their potential in wettability alteration and enhanced oil recovery as well as stability of them compared to each other have not been cleared yet; thus, an integrated comparison of them seems necessary. In this study, in addition to evaluating stability and price of these nanoparticles, their impacts on wettability alteration and EOR were investigated on oil-wet sandstone core samples. By injecting the nanofluids prepared from these nanoparticles, it could be expected to alter the rock wettability condition from oil-wet to water-wet due to their hydrophilic properties. For this purpose in this research, ten similar slices of the core samples were floated in ten different concentrations of the nanofluids; and their wettability alterations were determined by measuring the contact angles through sessile drop technique at different aging times. Then, brine and the nanofluids were injected to the three similar core samples to evaluate oil recovery caused by injection scenario. The results indicated that Titania, Silica and Alumina nanoparticles, respectively, had the most impacts on wettability alteration in the rock and their impacts incremented by increasing the nanoparticles concentration. After the injections of Titania, Silica and Alumina nanofluids with the optimum concentration at 0.1 wt%, the ultimate oil recovery is enhanced up to 18.27, 15.66 and 12.38 %, respectively, compared to the waterflooding. However, challenges of the use of these nanoparticles including the lack of stability and price of Alumina and Titania which are types of metal oxide-based nanoparticles were more than Silica.

Foaming phenomenon is one of the main problems in the gas refining process. Antifoams can be used for solving this undesirable problem. The current study was carried out with the aim of determining the optimum amount of effective parameters on foaming phenomenon in the absorption tower of Ilam gas refinery. An experimental design was used to quantify the effects of variables, including the amine concentration, the gas flow rate, and temperature, on amount of foam as response. The experiments were carried out using MDEA and foam measuring apparatus. A quadratic model was developed to correlate the relationship between variables and the response. The results demonstrated the accuracy of the model and show that the foaming strongly depended on temperature. The optimum operating condition with the less amount of foam can be obtained with an amine concentration of 35.19 (wt.%), gas flow rate of 1.63 (L/min), and temperature of 40.21 (°C). The best antifoam was determined among four different kind of antifoam i.e., silicon based (SAG 7133 and SAG 220) and alcohol based (KX-1415 and PN-30) in the optimum operating condition. SAG 7133 was chosen as the most effective antifoam.

In this paper, the investigation of LNG-BOG re-liquefaction system has been performed, and the considerable system is analyzed based on energy conservation law and entropy generation principles. For these analyses, first the conservation of energy analysis is performed, and thermodynamic properties (pressure and temperature) of the cycle are defined. Then, entropy generation values in all components are calculated. The exergy destruction in each component and exergetic efficiency is calculated based on entropy generation values. Finally, NLP multi-objective function of the refrigeration cycle is performed for lowest entropy generation and highest exergetic efficiency. Results show good improvement in LNG-BOG re-liquefaction system characteristics.