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... 

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... 

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.... 

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... 

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... 

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... 

Additional to Temperature, Pressure and Compositional changes of crude oils, Electro-kinetics and Electrical potential effects are also known as the most influencing parameters on Asphaltene deposition during oil production and processing.Mechanisms of electro-kinetics and asphaltene charge generation are very complex and unclear. In the previous studies on asphaltene precipitation and deposition, mostly electro-kinetics effects are ignored.While, recent studies show the great effects of electrical filed on asphaltene deposition during production and processing phase of crude oils.At reservoir porous medium and crude flow line, an electrical field can be developed along the length of the... 

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... 

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... 

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... 

In this study, for investigation of water salinity effect on asphaltene modeling, PC-SAFT equation of state has been used. All steps of modeling have been done by C sharp programming language software. Nghiem model has been used for modeling of asphalting pure solid. In this model, the heaviest component is split into two precipitating and nonprecipitation parts that their physical properties are the same in each part. Furthermore, to determine the exact mechanism of asphaltene precipitation, an oil model (Asphaltene+heptan+tuloene) in the presence of different water brine such as synthetic brine (with MgCl2, CaCl2, and Na2SO4 salts), seawater) ten and two times diluted), and formation water... 

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...