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... 

In this research, the behavior of surfactin at the presence of water, decane, and asphaltene is investigated. Decane is chosen instead of crude oil to simplify the model. In the first chapter, basic molecular structures are introduced. Furthermore, in the second chapter molecular dynamics simulation, as the main tool in these simulations, is introduced. In the third chapter, one of the most important quantities in chemical engineering, diffusion coefficient, is chosen to investigate the efficiency and accuracy of molecular dynamics simulation method to calculate such a quantity and results show that molecular dynamics simulation can present accurate quantities, more accurate than common... 

Interfacial Tension (IFT) as a main parameter for gas flooding efficiency in oil reservoirs depends highly on pressure, temperature, and composition of the reservoir fluids. Therefore, it is important to measure this parameter at real reservoir condition for successful field development plan. In this study, an axisymmetric drop shape analysis (ADSA) has been utilized to measure the equilibrium IFTs in crude oil-CO2 as well as crude oil-N2 systems at different temperatures and pressures. Moreover, minimum miscibility pressures (MMP) and first-contact miscibility pressures (Pmax) of crude oil/CO2 and crude oil/N2 systems at different temperature levels are determined by applying vanishing... 

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... 

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... 

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... 

Interfacial Tension (IFT) behavior of crude oil/CO2 system is recognized as the main factor affecting the efficiency of CO2 flooding during enhanced oil recovery (EOR) process. Adding paraffin group hydrocarbon to asphaltenic crude oils as an asphaltene precipitant component is aimed to mimic asphaltene precipitation process during crude oil production and transportation. Asphaltene precipitation would critically effects the IFT behavior of crude oil/CO2 systems. In the first part of this study, the equilibrium densities of oil samples which contain different heptane ratio were measured at different pressures and the temperature of 323 K. Then, the equilibrium IFT between CO2 and the crude... 

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... 

Water in oil emulsion usually forms during natural water encroachment or enhanced oil recovery processes due to the reaction between asphaltenic and naphthenic acid part of oil with brine in some heavy oil reservoirs. This results in major production challenges because of high w/o emulsion viscosity which leads to significant pressure drops. Therefore, it is essential to investigate the dominant mechanisms of w/o emulsion flow in porous media to overcome the production challenges. In the present study, w/o emulsion behavior is investigated through both static and dynamic tests. The w/o emulsion was prepared through mixing of a crude with brine using magnet stirrer. Emulsion stability... 

Wax precipitation may occur in production or transportation of crude oil form field which is a serious problem in petroleum industry. Flow assurance issues concerning wax precipitation make it necessary to develop a precise thermodynamic model to predict the wax appearance temperature and amount of precipitation at different conditions. In this work a new procedure has been proposed to characterize crude oil based on the SARA test considering the wax and asphaltene as single pseudo components. Two scenarios have been investigated for the survey of the crude oil characterization, with and without asphaltene pseudo component. Also, in this work, the Perturbed ... 

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.... 

Given the decreasing trend of light petroleum reserves and the necessity to produce heavy and extra-heavy oil resources, the challenge of dealing with existing asphaltene related problems, which is the heaviest and the most complex component of crude oil, has become increasingly tangible. Asphaltene precipitates and deposits due to pressure, temperature or composition alterations which leads to obstruction of porous media and production facilities. Set the costly methods aside, one of the available approaches to prevent asphaltene precipitation, is to apply an electric field upon the suspected zone, which is cheap and uncomplicated. Besides, utilizing nano-particles while applying electric... 

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... 

The Oil wells are usually damaged because of the drilling process and production scenarios or fluid injection during EOR processes. These damages would critically affect the rate of production and injectivity of the well in the form of plugging damage. Different methods are used to fix these damages and increase the production flow from the oil wells. One of the most widely used well-stimulation methods to remediate this challenge is well acidizing. Although this method has very high efficiency in improving the ability of wells, if it is not designed and implemented correctly and optimally, it can cause induced damage and even lead to the well shutting. This challenge is especially reported... 

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... 

Formation damage is probable to occur while drilling, work-over operations, and well completion in near wellbore zone due to different reasons; which leads to excess pressure drop through this area. Well stimulation operations are proposed to remove these damages and improve oil production; among which, acidizing is known as a traditional applicable method to stimulate oil and gas wells. Although this approach is accepted and chosen as a well stimulation method to remove formation damages, its poor design and implementation results in new formation damages. One of these arises when acid contacts asphaltic oil, which causes asphaltene particle instability and asphaltic sludge rapid... 

Microbial enhanced oil recovery (MEOR) is a collection of techniques that utilize microorganisms and their metabolic products to improve the recovery of crude oil from reservoir rock. From the advantages of this method, independency to the oil price and environmental benign can be mentioned. Many mechanisms have been proposed to contribute on MEOR, but still there is no enough knowledge about the mechanisms that causes inabilities in manipulating the process to get more oil production.
In the present study, the effect of a native type of bacteria, Enterobacter cloacae, on the glass surfaces wettability which were aged in expose of model oil with different asphaltene concentration was... 

Asphaltene are the heaviest components if some crude oil which are in thermodynamic equilibrium. Any change in the equilibrium condition including change in temperature, pressure or composition may render asphaltene to come out of solution and precipitate. Asphaltene precipitation and deposition is one of the main problems in some of the oil fields. Precipitated asphaltene may deposit in the reservoir, near wellbore, wellstring, transport pipeline and surface facilities. In porous media, the deposited asphaltene over the surface and/or across pore throat can severely reduce the effective permeability and results in decreasing of the oil production. Also, the deposited asphaltene results in... 

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...