Sharif Digital Repository

One of the main problems associated with the oil production is asphaltene precipitate in the reservoirs. In order to plan for the EOR methods, production scenario, and selection of completion technology, it is necessary to study the initiation of asphaltene precipitation called onset. Since the experimental methods is not only is so expensive and time consuming, the required materials are not available. Consequently, modeling approaches as new methods are proper substitutes for laboratory procedure. These methods need less costs and time and higher accuracy compared to the experimental investigations which are the advantages of these methods. Computational operations for onset determination... 

This work concerns with experimental and modeling investigation of the asphaltene damage removal using ultrasonic wave irradiation. A specific core holder apparatus was designed and utilized for in situ ultrasonic exposure to damaged core plug at different conditions of exposure time, ultrasound power and distances between sound source and plug. Injection of many pore volumes of an asphaltenic crude oil was used for creating asphaltene induced damaged in porous media through permeability measurements. The deposited asphaltene during oil injection as well as asphaltene removal due to ultrasonic exposure was evaluated using IP-143 analysis. The results revealed that ultrasound application... 

Asphaltene precipitation and deposition may cause severe problems during different stages of oil recovery. All proposed remediation techniques have proven costly and not highly effective, so prevention becomes the most beneficial way to counteract the problem. Revelation of the deposition mechanism and determination of the parameters are necessary in order to devise reliable prevention strategies.This work presents results of the effect of lean gas and CO2 injection process as well as natural depletion on dynamic asphaltene precipitation and deposition. In addition sets of experiments were performed in the same porous media using STO and solvent (with different volume ratios) to investigate... 

Asphaltenedeposition is a major problem during natural depletion and EOR processes due to formation damage issues. It is necessary to reveal asphaltene deposition mechanisms and its effective parameters to prepare an acceptable prevention strategy. Therefore, different natural depletion and EOR experiments must performed on core samples. In this research, Effect of CO2 injection on asphaltene deposition phenomena has been surveyed. Two carbonate core samples and one sandstone core sample was used in experiments. The oil used in these experiments was recombinedoilfrom one of Iranian offshore oilfield.In order to estimate permeability reduction during experiment, injection of oil and CO2 was... 

Crude oil is made up of dozens of chemicals which based on their structural similarity, SARA test separate it into four categories: saturates, aromatics, resins and asphaltene. Asphaltenes are recognized as the largest, heaviest and the most polarizable fraction of the crude oil which are in thermodynamic equilibrium with oil at reservoir conditions. Each of the physical, chemical, electrical or mechanical disruption of this balance during production can result in instability and asphaltene precipitation may occur and eventually led to deposition in the reservoir, wells, pipelines, etc. Due to the fact that most changes in temperature and pressure will generated in the wells, thus... 

Asphaltene deposition on reservoir rocks occurs during natural depletion as well as miscible injection processes. It causes reduction of effective pore space and consequent impairment of the ability of oil to flow through reservoir. Therefore, deposition of asphaltene causes significant formation damage and wellbore plugging, requiring expensive and difficult cleanup procedures. Thus it is necessary to be able to consider the onset, amount of deposition and also consequent damage of permeability and porosity reduction due to various factors. The objective of current work is to conduct experimental and simulation study of asphaltene deposition dynamics in one of the Iranian reservoirs. In... 

Efforts to identify, predict, and resolve problems linked to asphaltenes and flow assurance have resulted in the development of numerous laboratory and modelling techniques. However, there has been little research on the molecular structure of asphaltenes and how it relates to solubility, stability, aggregation, and deposition behavior. Not only was a thorough structural analysis of asphaltene extracted from three samples of light, medium, and heavy oil performed in this study, but medium oil asphaltene was also fractionated into three sub-fractions based on solubility, with minimum, medium, and maximum solubility, and each subfraction was subjected to a structural analysis. All asphaltene... 

In this thesis, by focusing on the hydraulics of three phase flow in vertical tubing to investigate asphaltene deposition problem, the solid particles behaviors in a turbulent flow is fully studied. Reasonable size distribution for particles (based on previous works and researches) was assumed and a model for 2 sections of a Marrat oil field well to evaluate their asphaltene deposition problem was developed. Three phase liquid-gas-solid flow in the well tubing was simulated. Asphaltene deposition profile on the well tubing, mean and maximum of the deposition rate and particle concentrations in the flow regime were calculated and compared with real field data. Better agreement with field data... 

Thermodynamic modeling is a useful method for predicting of asphaltene precipitation due to various reasons, such as CO2 injection, mixing of different oils in oil storage and pressure changes. However, the application of solid model and thermodynamic micellization model, for prediction of asphaltene precipitation under gas injection condition, hasnot been improved. In this work, two computer codes which are based on two different asphaltene precipitation thermodynamic models, 1-Thermodynamic Micellization Model and 2- Solid Model, have been developed, and, used for predicting of asphaltene precipitation data reported in the literature as well as the experimental data obtained from high... 

Asphaltene deposition, considered as the heaviest and the most polarizable fraction of crude oil, can cause severe problems in oil production and extraction systems. Oil production companies annually bear huge reduction or even cessation in production and, in turn, costs due to asphaltene precipitation and deposition in wellbore or production tubings. To gain more and better insight into asphaltene formation in production systems, the conceptual investigation on the mechanisms of asphaltene adsorption and deposition on a solid surface is indispensable. In this study Asphaltene's particle adsorption and deposition onto the metal surface under the effect of flow is investigated by experimental... 

Prediction and prevention from asphaltene deposition is an essential topic in oil production systems that can enormously increase oil production costs. Many studies have been done to understand and predict the behavior of asphaltene-containing oils. Prediction and investigation of asphaltene precipitation are required to predict the asphaltene deposition problem. Changes in temperature, pressure, and composition can cause precipitation, and these changes are inevitable during production. This dissertation compares the thermodynamic models that can simulate asphaltene precipitation. Firstly, A comprehensive review was done to extract the maximum amount of experimental data from the literature... 

In the upstream asphaltene flow assurance community, both academics and industries are actively involved to predict the asphaltene deposit profile in wellbores and pipelines. The main objective of this study is to contribute to the thermodynamic and transport modeling of asphaltene in order to predict its precipitation, aggregation and deposition. For a better knowledge of the flow properties of asphaltene containing crude oils, it is necessary to understand how asphaltene affect the rheological properties. In this work, the information on such rheological properties of oil-asphaltene slurry systems is provided. The results of rheological experiments for two Iranian crude oils show that the... 

Crude oil production could cause the thermodynamic equilibrium of the crude oil to be disturbed in the well column which results in asphaltene precipitation and deposition. The thickness of the deposited material grows over time until it completely blocks the well column.Due to the hard and insoluble nature of deposited asphaltene, the two main chemical and mechanical methods are found to be more effective. It should be noted that the actual organic sediments in the piping are not pure and consist of three components: asphaltene, resin and paraffin. Therefore, it is very important to know the composition of the deposited material before selecting the appropriate chemical solvent.The samples... 

The aim of this project was to upgrade and reduce viscosity of heavy oils by adsorbing of asphaltene on Ni-Mo/CB and converting it into lighter and more valuable gas and liquid compounds. Asphaltene has been extracted from a heavy crude oil sample of Soroush oil field in Iran. After adsorption, Asphaltene conversion to lighter components (gas/liquid) was studied through hydrocracking process. To prepare the support of catalyst, Carbon Black, initially a thermal treatment step under the argon gas atmosphere followed by acid-washing process was performed. Afterward, the catalysts was prepared through dry impregnation method. In order to activate catalyst for hydrocracking, the catalysts has... 

Formation, precipitation and deposition of heavy organic compounds of petroleum fluids including, but not limited to, asphaltene in oil reservoirs and production systems have been by far the most important and challenging flow assurance problems. Therefore, preventative actions to control organic deposits in oil formations and production systems which can lead inevitably to reduction or cessation in production, have always been a main challenge for oil producers.In this thesis, a one dimensional simulator have been developed to study asphaltene precipitation, aggregation and deposition in an oil well column at isothermal and non-isothermal conditions. While the previously proposed PC-SAFT... 

Asphaltene, the heaviest and most polarizable fraction of crude oil, has a potential to precipitate, deposit and plug pipelines, causing considerable production costs. The main objective of this study is to contribute to the thermodynamic and transport modeling of asphaltene in order to predict its precipitation, segregation and deposition. Potential calculation of some thermophysical properties of asphaltene is also explored. Predicting the flow assurance issues caused by asphaltene requires the ability to model the phase behavior of asphaltene as a function of pressure, temperature and composition. It has been previously demonstrated that the Perturbed Chain form of Statistical Association... 

Nitrogen injection is a promising enhanced oil recovery process. Asphaltene precipitation during miscible gas injection is a common problem in oilfields throughout the world. In this work, a comprehensive study is conducted on effect of gas injection on phase behavior and asphaltene instability of live oil samples. Effects of oil API, gas type and concentration, pressure and temperature are studied under natural depletion and nitrogen injection processes by means of high pressure filtration and a photographic procedure coupled with image analysis. Filtration results show that nitrogen destabilizes asphaltenes more compared to methane and the problem is more severe for heavier crude samples.... 

This study investigates the dynamic adsorption of asphaltene-in-toluene solutions on pack of wet calcite. All experiments were performed on mineral packs in sand-pack with mesh sizes between 100 to 140 (105 to 150 micron) and porosities between 40 to 46 percent. A UV–vis spectrophotometer was used to monitor the outlet concentration of asphaltenes. Experiments were performed for seven ionic strength of sodium chloride (6 to 1500 mM), five ionic strength of sodium sulfate (6 to 2400 mM) and four ionic strength of these salts mixture (12 to 3300 mM). In previous experiments the asphaltene concentration is 500 mg/l. Also two experments were performed with asphaltene concentration of 2000... 

The study of low-salinity water flooding or smart water flooding as secondary or tertiary oil recovery methods started in 1960 and many researchers have studied the effect of ions types on asphaltene precipitation/deposition during the injecting water into the oil reservoirs. To reduce the asphaltene challenges, one needs to properly investigate this phenomenon and better understanding of the cause of precipitation. It is already known that the amount of asphaltene deposition can be reduced by controlling the deposition criteria. For example, water microemulsion in the oil phase would cause the asphaltenes to be adsorbed on the water oil interface by hydrogen bonds due to heteroatom... 

Water injection, as one of the conventional methods to increase the oil recovery factor has always been at the center of research works for Enhanced Oil Recovery (EOR). The conducted studies show that by controlling the amount and type of ions in the injected water, the recovery efficiency can be improved. In the meantime, most of the investigations are focused on the interaction between water/rock/oil to trace the wettability alteration. However, these interactions especially between the injected water and the oil phase, would lead to change of surface charge distribution of the reservoir rock. Besides, this effect can change some of the characteristics of the fluid phases, especially in...