In petroleum production processes, stable emulsions are extracted along with crude oil. The stability of these emulsions, primarily due to the presence of naturally occurring surface-active compounds in crude oil, leads to various operational and environmental challenges. Therefore, the effective separation of these emulsions is considered one of the critical and essential challenges in the petroleum industry. To provide an effective solution to this challenge, a hyperbranched polymeric demulsifier based on a polyester structure was synthesized in this study via direct polycondensation between a trifunctional polyalkylene glycol as the branching agent and a difunctional isophthalic acid. The hyperbranched structure, with a higher density of end-groups, enables multi-point and faster adsorption at the interface. A series of characterization analyses were performed to confirm the structure and the successful synthesis of the demulsifier, and the results verified the effectiveness of the synthesis process. The performance of the synthesized demulsifier in water-in-oil emulsion separation was evaluated under various operational conditions, specifically demulsifier concentrations ranging from 50 to 100 mg/L, temperatures from 40 to 70°C, and settling times from 10 to 60 minutes. Under the optimal conditions, including concentration of 90 mg/L, temperature of 70°C, and settling time of 50 minutes, demulsification efficiency of approximately 85% was achieved. In addition to its amphiphilic nature, the hyperbranched polymeric demulsifier exhibits acceptable separation performance due to its hyperbranched structure and favorable properties, including an appropriate molecular weight, relatively uniform structure, and high flexibility of the polymer chains. Subsequently, in order to further enhance the performance of the hyperbranched polymeric demulsifier and investigate the effect of magnetic nanoparticles on this system, magnetic graphene oxide nanoparticles were synthesized and incorporated into the system as a modifying agent. Under the previously determined optimal conditions and at a concentration of 0.025wt%, these nanoparticles increased the demulsification efficiency to 95.6%. In addition, the magnetic properties of the nanoparticles enabled their efficient recovery from the system, which not only reduced material consumption and operational costs but also demonstrated the potential for their reuse. Overall, the results of this study demonstrate that the synthesis of a hyperbranched polymeric demulsifier and its modification with magnetic graphene oxide nanoparticles provide a novel and innovative approach for the demulsification of water-in-oil emulsions. Furthermore, due to the high potential of this system in emulsion separation, the findings of this research can be utilized for industrial applications and further research studies in the petroleum industry.   

Acidizing is an effective method for enhancing production in carbonate reservoirs, but hydrochloric acid (HCl) has limitations due to its high reaction rate and high corrosivity. These challenges make process control difficult and increase operational costs. As a result, research has shifted toward alternative fluids with slower reactivity and lower corrosivity. One innovative approach in this area is the use of emulsion acids, which help improve reaction control and reduce corrosivity. This study focuses on investigating and optimizing stable emulsion acids to reduce the reaction rate with carbonate rock. For this purpose, the appropriate surfactant combination, optimal HLB (Hydrophilic-Lipophilic Balance), and the effects of salts and nanoparticles on emulsion stability were examined. All emulsion acids were prepared with a 70:30 acid-to-diesel ratio and 15 wt% HCl. Their thermal stability was evaluated at 60°C and 80°C. Surfactants Span 80, Tween 80, CTAB, and SDS did not provide satisfactory stability on their own. Due to its lipophilicity and high HLB, Span 80 was selected as the primary surfactant. The combination of two surfactants with optimal HLB increased emulsion stability compared to the single surfactant systems. However, the combination of the non-ionic surfactants Span 80 and Tween 80 exhibited the least stability. Adding KCl salt to the surfactant mixture improved stability and delayed phase separation. Nanoparticles of tannic acid, boehmite (AlOOH), and graphitic carbon nitride (g _C3N4

   Absteract Matrix acidization in carbonate reservoirs is a process that has long been used to increase productivity in oil and gas formations. The main goal is to create wormholes that bypass existing damage in the formation. HCl is the main acid used for the method. The use of this acid comes with major challenges, including high reaction speed, high corrosion rate, and penetration into highly permeable areas, especially in heterogeneous formations, which negatively affects the success rate of this method. Several techniques have been proposed to overcome this problem, one of which is the use of emulsified acids, which has been widely used. In this laboratory study, 15 wt% HCl was used as the internal phase, diesel oil as the external phase, and surfactant as the emulsion stabilizer to produce a stable W/O emulsion at high temperature conditions. To increase the stability of the emulsion, there is a set of parameters that include the ratio of acid to diesel, type and concentration of surfactant, HLB of surfactant, mixing time, mixing speed, etc. By obtaining the optimal values ??of these parameters, we produced a set of emulsions with different stabilities. In order to reach the optimal HLB and increase the stability, different cosurfactants were used in combination with surfactant with different weight ratios. Also, to increase the stability of the emulsion, instead of using high amounts of surfactant, PMBA, PEG-CA and curcumin polysulfide nanoparticles with different hydrophilicity degrees were used in low amounts of about 1000 ppm, and PMBA had a great effect on increasing the stability due to its dual-friendliness properties. After the production of the emulsions, kinetic tests were designed to compare its performance with ordinary acid. In these tests, the dissolution rate of calcite mineral in ordinary acid and emulsion was used as a criterion for comparison. In ordinary acid, the reaction started from the very beginning of the contact between the rock and the acid and ended quickly, but in emulsion acids, it took a while for the reaction to start after the contact between the rock and the acid, and after the reaction started, the dissolution rate was lower than that of ordinary acid, in other words, the reaction was slower. Therefore, by observing the results obtained, emulsion acid has the ability to delay the diffusion of hydronium ions and also has the ability to reduce the reaction rate.   

Seismic isolation is one of the most effective technologies available in reducing the seismic response of many structures. Elastomeric isolators reinforced with steel plates are considered one of the conventional types of seismic isolators that have good isolation performance in large and heavy structures. The use of these isolators in lightweight structures lacks technical justification due to the inability to achieve appropriate isolation periods. The aim of the present study is to investigate the behavior of a new type of elastomeric isolators with effective application in lightweight structures. The isolators under study are fiber-reinforced elastomeric isolators with a circular cross-section with holes that are used as supports. Due to the elimination of the end steel plates and the smaller volume of materials used in the construction of the isolator, the total cost is reduced. The presence of a central hole in the isolator leads to a decrease in the effective horizontal stiffness of the isolator and, as a result, an increase in its seismic isolation efficiency. So that these isolators, which have both high technical potential and low economic cost, can be used to isolate light structures and heavy industrial equipment. In this study, using the finite element software Abaqus, these types of isolators have been designed and analyzed with the aim of isolating light structures for effective vertical forces of 150, 250 and 350 kN. Under each of the mentioned vertical loads, three different types of isolators with the same external diameters and different internal diameters have been designed. The internal diameter (hollow diameter) is considered as a variable and the force-displacement curves of the isolators in the vertical and lateral directions have been determined by finite element analysis and the reduction in their vertical and horizontal stiffnesses compared to the corresponding solid circular isolator has been obtained. In the following, two analytical equations for calculating the vertical and horizontal stiffnesses of circular isolators with holes, considering their supporting boundary conditions, have been obtained through regression with an error of less than 10%. These relationships can be used for the initial design of supported circular hollow fiber reinforced elastomeric isolators.   

   Abstract The use of supplemental dampers is considered one of the innovative methods for seismic retrofitting of structures. Among the various types of dampers, buckling-restrained braces (BRBs) are more commonly utilized across the country. This study investigates the impact of BRBs installed on scissor-like bases on the structural performance of a three-story frame. The primary objective is to evaluate the influence of design parameters such as the length and installation angle of the BRBs on controlling structural vibrations. The studied frame, used in the SAC project and well-documented in the literature, serves as the basis for this research. Nonlinear time history analyses are employed to assess the seismic behavior of the structure, including base shear, column moments, maximum roof displacements, and energy curves, both with and without BRBs. The study aims to evaluate the effectiveness of different BRB configurations in reducing seismic responses. The structural modeling and BRB integration were conducted using the SAP2000 software. Force-displacement hysteresis curves of the BRBs were also extracted and analyzed to identify the optimal length and installation angle. The BRBs used in this research, referred to as Chevron Base BRB 3, feature two dampers installed on scissor-like bases resembling a figure-eight configuration. The optimal installation angle for Chevron-based BRBs was found to be 45 degrees, while the ideal BRB length was determined to be 2.5 meters. The findings of this study are specific to the analyzed frame and may not necessarily be generalized to other frames or structural systems. Keywords:

Earthquakes are one of the damaging factors that threaten the stability of technical buildings and vital arteries in many parts of the country. Therefore, seismic improvement of structures and technical equipment in vital arteries is necessary for the sustainable development of the country. Ground-mounted power transformers located in power distribution substations in urban areas are an example of technical equipment vulnerable to earthquakes. Due to the significant mass of these equipment, a significant inertial force is exerted on them during an earthquake, which can cause the equipment to slip or overturn and disrupt its performance by causing damage. One of these effective methods of seismic improvement of the described equipment is to reduce the accelerations affecting them during an earthquake using seismic isolation technology. The purpose of the present study is to study the feasibility of isolating heavy technical equipment with limited dimensions using only one elastomeric isolator reinforced with supporting ring fibers. To achieve the research objectives, ring isolators with different dimensions were designed for a selected transformer weighing 5000kg using the finite element software Abaqus. The outer and inner diameters of the isolator were changed as design variable parameters to study their effect on the lateral behavior of the isolators. In the present study, the range of changes in the outer diameter was from 1000mm to 2000mm and the range of the ratio of the inner diameter to the outer diameter in the studied isolators was 0.7 and 0.9. The results of numerical analyses show that with increasing the inner diameter of the isolator, the effective lateral stiffness and its lateral displacement capacity decrease. The achievable separation period in the isolated transformer can be increased by 1.5s and the maximum ground acceleration effective on the equipment can be reduced by 45%. Another part of this research is to develop analytical relations to estimate the vertical and lateral stiffnesses of ring isolators. The analytical relations presented in this study can be used in the initial design of the isolators. The results of this feasibility study show that fiber-reinforced elastomeric ring isolators have good potential for application in seismic isolation of technical equipment. However, for the practical application of these isolators in technical equipment, it is necessary to conduct laboratory studies and investigate the effect of various parameters on their behavior.   

One of the most important problems of oil reservoirs is damage to the formation, which occurs due to induced and natural factors. The most common method to repair the damage to the formation and increase the productivity of the well is acidizing. Among the important acids for matrix acidification in carbonate tanks, he mentioned organic and inorganic acids, especially hydrochloric acid. In some oil fields, such as the Azar oil field, due to the high temperature and pressure in the drilled well, the speed of acid reaction with the reservoir rock increases, which in turn causes the intensification of sludge generation. Failure to create wormholes. In addition, acids based on hydrochloric acid cause corrosion in the wall pipes of wells. One of the ways to control the reaction kinetics is the use of hybrid acids. Citric acid as an effective organic acid as well as glutamic acid as a chelating acid along with pure hydrochloric acid can be used in acidification of oil fields. Due to their reversibility and low dissociation constant, these acids reduce the reaction rate of acids and are less corrosive and anticorrosive than mineral acids. The purpose of this research is to investigate the effect of hydrochloric-citric acid mixture as well as hydrochloric-glutamic acid on carbonate rock samples and compare it with pure hydrochloric acid, as well as to investigate the changes in the concentration and speed of the impact time of these three types of carbonate acid. In this research, the purpose of measuring the concentration The optimal combination of hydrochloric acid-citric acid-hydrochloric acid-glutamic acid is high temperature in Azar field oil reservoirs. The design of the experiment is by RSM method with two concentration factors of hydrochloric acid and citric acid, respectively, at two levels of 5-15 for hydrochloric acid, two levels of 10-5 for citric acid, and also 8.5% of glutamic acid. It has been used. The method of kinetic calculations based on determining the concentration of the reactant (H+) by the tetration method has been used. In this research, in order to achieve the best concentration of hybrid acid, the qualitative analysis of the results obtained from the experiments was used, and the concentration of 10% hydrochloric acid, 7.5% citric acid, and 8.5% glutamic acid was chosen as the best and most optimal concentration of hybrid acid. It has been achieved. At the end, kinetic experiments were performed at three temperatures of 80, 60 and 40 degrees Celsius on acids with concentrations of 10% citric - 7.5% hydrochloric and 10% glutamic - 8.5% hydrochloric acid with the sample stone until the parameters of the reaction weight. Calculate. The obtained results showed that two separate reactions took place, in the first phase of the reaction, the predominant acid was hydrochloric acid, and in the second stage, the dominant mechanism was with citric acid or glutamic acid.   

acidizing   is the most useful method to deal with damage to the formation. The reservoir rock must have high permeability so that the fluid is not trapped in the pores of the rock. In the design of acidizing operation, one of the biggest problems is determining the amount of effective parameters in well stimulation.In this research, we try to control the reaction rate at high temperature in the oil wells of Azar field by using a mixture of hydrochloric acid and acetic acid. Mixing inorganic acid with organic acid can have many advantages in controlling the reaction rate, especially in high temperature formations. The prerequisite for using this mixture is a detailed knowledge of the kinetics of the stone dissolution reaction in acid. In this research, the changes in the kinetics of rock reaction from calcite carbonate outcrop and the mixture of hydrochloric acid and acetic acid were investigated in the framework of a quick and low-cost test. All the experiments related to the research were conducted in three phases, in the first phase experiments were conducted to learn more about the testing process and to observe the difference between the corrosion of the sample rock with mineral acid and hybrid acid. In the second phase, the goal was to obtain the optimal point, for this purpose Minitab software was used, and according to the intended result and the applications of the central composite design method, this method was used. The range of concentrations was defined as 5 to 15 for hydrochloric acid and 5 to 10 for acetic acid. A total of 13 experiments were obtained, which were tested at a temperature of 50 degrees. The answers obtained from the second phase tests were entered into Minitab software in two ways: all concentrations at different times and all normalized concentrations at different times. But both methods did not have the desired results and could not be used in further research. To continue the research process, the qualitative analysis of the graphs obtained from the experiments was used. According to their analysis, the concentration of 5% hydrochloric acid and 5% acetic acid was chosen as the optimal concentration. In the third phase of experiments, the optimal concentration obtained was tested at temperatures of 40, 60 and 80 degrees Celsius. The comparison of the profile of concentration changes of two samples showed that acetic acid had the ability to replace the consumed H+ ions with continuous and gradual dissociation. Compared to pure hydrochloric acid, this compound has a higher final concentration of 2 M, and at the same time, its reaction speed is lower than pure hydrochloric acid. Therefore, in addition to the positive effects of organic acid on corrosion and control of iron ions, it is also possible to dissolve rock in greater depths of the tank.   

Hydrochloric acid is commonly used in matrix acidizing in carbonate reservoirs, but is problematic in deep wells due to its high reactivity and tendency to form sludge when the acid comes into contact with asphaltic crude oil. Additionally, HCl-based acids are highly corrosive to well tubing. One of the solutions to this problem is the use of hybrid acids. Formic acid, as one of the main organic acids, along with pure HCl, is often used in the acidification of oil fields. This ionized acid is weak and shows a slow reaction and is less corrosive than mineral acids and has inhibitory capabilities. Our goal in this research is to investigate the effect of hybrid hydrochloric-formic acid on samples of carbonate rock and compare it with pure HCl acid, as well as to investigate changes in the concentration and duration of the effects of these two types of acid on carbonate rock. The positive effect of using hybrid acids compared to pure HCl acid is evident in the test results, which we will discuss in detail later. In this research, the aim is to measure the optimal concentration for an acid that can be used at high temperature, and this acid is used for use in one of Iran's oil formations. For this, the method of kinetic calculations based on titration was used. The design of the experiment was considered by RSM method with two factors of hydrochloric acid concentration and formic acid concentration at two levels of 5-15 for HCl acid and two levels of 5-10 for FA acid. In this research, to evaluate the best concentration of hybrid acid, experimental design and qualitative analysis of the results obtained from the experiments were used, and the concentration of 10% hydrochloric acid and 7.5% formic acid was obtained as the best concentration of hybrid acid. At the end, kinetic experiments were performed at three temperatures of 40, 60, and 80 degrees Celsius on acid with optimal concentration along with stone to calculate the kinetic parameters of the reaction. The results showed that two separate first-order reactions occurred. During the first 28 minutes of the reaction, the dominant acid was hydrochloric acid, and from the 33rd minute onwards, the dominant mechanism was with formic acid. The amount of activation energy was calculated in the first stage for hydrochloric acid 192/8267 J/mol and in the second stage it was obtained for formic acid 9334/127 J/mol.