Sharif Digital Repository

The vapor extraction process (or VAPEX) uses vaporized solvents injected into a horizontal well to form a vapor chamber within the reservoir. Vapor dissolves in the oil and enhances the oil production by decreasing the oil viscosity in heavy oil reservoirs. To evaluate the process we conduct a simulation study on an Iranian heavy oil reservoir called Kuh-e-Mond. In addition, a semi-analytical investigation of the VAPEX process has been performed. The idea is to perform VAPEX simulation for a laboratory model and find a methodology to compare the results of the simulator with the semi-analytical Butler's model. In particular, a semi-analytical dimensionless correlation for production rate... 

Asphaltene precipitation problems manifest themselves in different stages of oil reservoirs production. Experimental and modeling investigations are, therefore, employed as promising tools to assist in predictions of asphaltene precipitation problems and selection of proper production facilities. This study concerns experimental and modeling investigations of asphaltene precipitation during natural production and gas injection operations for a heavy Iranian crude oil at reservoir conditions. First, with design and performance of high pressure-high temperature experiments, asphaltene precipitation behavior is comprehensively investigated; the effects of pressure and temperature are fully... 

Gas injection into reservoirs can be used to increase oil recovery. However, reservoir heterogeneity and high gas mobility reduce sweep efficiency and decrease recovery. Using foam can reduce gas mobility and therefore increase sweep efficiency. Foam is thermodynamically unstable, so it is important to predict the foam stability. In order to understand the influence of oil presence on foam stability, static experiments performed on foam by varying the type and amount of added oil and molecular weight of added alkane. Also static foam properties have been investigated by varying the surfactant concentration, ionic strength, composition of different salts in the sample, and addition of polymer... 

Many reservoir and production engineers face asphaltene precipitation as a major problem during miscible carbon dioxide flooding projects. Experimental studies regarding asphaltene precipitation are therefore employed to assist in selecting appropriate facilities and proper operation schemes. During this study, a series of high pressure, high temperature experiments are designed and performed to analyze asphaltene precipitation behavior of an Iranian light reservoir crude at reservoir conditions due to natural production and miscible CO2 gas injection. For both sets of experiments, two different temperature levels (including reservoir temperature) are selected to investigate the role of... 

Steam-assisted gravity drainage is one of the most promising strategies to develop huge heavy oil and bitumen accumulations. Like the other thermal processes, this method aims at reducing oil viscosity by increasing the temperature. But in an economical point of view, it requires a great volume of steam for injection. Moreover, early breakthrough of steam and high steam-oil ratio makes it uneconomical, especially in long production time. In this study, a new method, two wells cyclical steam-assisted gravity drainage is compared with a conventional steam-assisted gravity drainage process. Well configuration in two wells cyclical steam-assisted gravity drainage is the same as the... 

The Vapour Assisted Petroleum Extraction (VAPEX) process, a newly developed Enhanced Heavy Oil Recovery process, is a promising EOR method for certain conventional non-fractured heavy oil sandstone reservoirs such as those in Canada, but its applicability on low permeable Naturally Fractured Reservoirs (NFR) such as those in the Middle East and Persian Gulf still remained as a question. Previous studies show that the foremost concern for VAPEX application in the case of NFR is the low non-economical production rates. The aim of the present work is to study the effect of fractures geometrical properties such as orientation (vertical or horizontal), density, spacing, location and networking on... 

The vapor extraction process (or VAPEX) uses vaporized solvents injected into a horizontal well to form a vapor chamber within the reservoir. Vapor dissolves in the oil and enhances the oil production by decreasing the oil viscosity in heavy oil reservoirs. To evaluate the process we conduct a simulation study on an Iranian heavy oil reservoir called Kuh-e-Mond. In addition, a semi-analytical investigation of the VAPEX process has been performed. The idea is to perform VAPEX simulation for a laboratory model and find a methodology to compare the results of the simulator with the semi-analytical Butler's model. In particular, a semi-analytical dimensionless correlation for production rate... 

A comprehensive understanding of the role of reservoir heterogeneities induced by flow barriers and connate water on sweep efficiency of different EOR scenarios is rarely attended in the available literature. In this work, different miscible/immiscible EOR processes were conducted on various one-quarter five-spot glass micromodels incorporating small-scale flow barriers. Microscopic and macroscopic observations revealed the reduction of sweep efficiency, premature breakthrough of displacing fluids, the severity of fingering at displacement front which leaves a large amount of oil behind the flow barriers untouched, and significant increasing trend of oil recovery after breakthrough in the... 

Nitrogen has been valued as an economical alternative injection gas for gas-based enhanced oil recovery (EOR) processes. Minimum miscibility pressure (MMP) is the most important parameter to successfully design N2 flooding. In this communication, a data bank covering wide ranges of thermodynamic and compositional conditions was gathered from open literature. Afterward, a rigorous approach, namely least square support vector machine (LSSVM) optimized with coupled simulated annealing (CSA) was proposed to develop a reliable and robust model for the prediction of MMP of pure/impure N2–crude oil. The results of this study showed that the proposed model is more reliable and accurate than the... 

Asphaltene precipitation and deposition within the reservoir formation is one of the main concerns during enhanced oil recovery (EOR) processes especially during the gas injection. In the current study, different aspects of carbon dioxide (CO2) and nitrogen (N2) injection in the reservoir, was thoroughly examined. The feasibility of using these gases as the injection gas was explored using Bayesian network-based screening method. After recombination and preparation of the live crude oil, precipitation of asphaltene using vanishing interfacial tension (VIT) method and core flooding experimentation was examined. Besides, swelling test was utilized to investigate the effect of CO2 and N2... 

The impacts of salinity adjustment of displacing fluid have recently gained special attention to enhanced oil recovery (EOR). Different mechanisms have been studied widely in the literature while some of them are still subjugated to more scrutiny. The effects of diluted sea water on the interfacial properties of brine and asphaltenic-acidic crude oil and the wettability alteration of carbonate reservoir rock are investigated in this experimental observational work. The measurements of interfacial tension (IFT) and contact angle (CA) as two main parameters are studied. Besides, the effects of asphaltene and resin in the crude oil on the IFT values between the crude oil and aqueous solution... 

Carbonated water has been recently proposed as an enhanced oil recovery method for crude oil reservoirs. Interfacial tension (IFT) plays a crucial rule on the displacement of trapped oil ganglia in the porous media. This investigation is designed to systematically assess the dynamic interfacial tension (DIFT) of two different types of crude oils with carbonated water (CW). In addition, the measured experimental data were applied into specified models. The DIFT behavior of acidic and non-acidic crude oil samples/CW and deionized water (DW) are also compared to find the effect of dissolved carbon dioxide in water on IFT. At the next stage, DIFT of all the results were used through three... 

The strength of a newly formulated surfactant with an alkali and polymer (AS/ASP) to improve an acidic heavy oil recovery was laboratory evaluated by various flooding experiments. The comparative role of the parameters like chemical nature, surface wettability, salinity, temperature and injection scheme were explored at high temperature and pressure on Berea sandstone rocks. According to the results the anionic surfactant is capable of providing proper oil displacement under high salinity conditions around 15 wt%. Continuous monitoring of differential pressure response and effluents’ state clearly represented the formation of an emulsified oil in high saline solutions with both alkali and... 

In this way, after experimental measurement of interfacial tension, different models including mono-exponential decay, dynamic adsorption models and empirical equation are used to correlate this time-dependent behavior of interfacial tension (IFT). During the modeling approach, the induction, adsorption, equilibrium, and meso-equilibrium times as well as diffusivity of surface active components known as natural surfactant including asphaltene and resin from crude oil to the interface are obtained. In addition, the surface excess concentration of surface active components at the interface and Gibbs adsorption isotherm are utilized to analyze the measured dynamic IFTs. Finally, the mechanisms... 

The Steam Assisted Gravity Drainage (SAGD) process, a developed Enhanced Oil Recovery (EOR) process to recover oil and bitumen, has been studied theoretically and experimentally in conventional reservoirs and models and is found a promising EOR method for certain heavy oil reservoirs. In this work simulation studies of the SAGD process were made on different fractured models consisting of fractures in both Near Well Region (NWR) and Above Well Region (AWR) and even in the presence of networked fractures. At early stage of the SAGD process in fractured system, steam moves through the fractures first and then the matrix blocks are heated primarily by conduction and possibly some steam... 

Considering the dramatic increase of greenhouse gases concentration in the atmosphere, especially carbon dioxide, reduction of these gases seems necessary to combat global warming. Fossil fuel power plants are one of the main sources of CO2 emission and several methods are under development to capture CO2 from power plants. In this paper, CO2 capture from a natural gas fired steam cycle power plant using oxyfuel combustion technology is studied. Oxy-fuel combustion is an interesting option since CO2 concentration in the flue gas is highly increased. The Integrated Environmental Control Model (IECM) developed by Carnegie Mellon University (USA) is used to evaluate the effect of this capture... 

This experimental study is aimed at evaluation of the performance of secondary WAG injection in carbonate cores at different pressures. To do so, a comprehensive series of high-pressure high-temperature (HPHT) core flooding tests are conducted. The fluid system includes reservoir dead and live crude oil, CO 2, and synthetic brine while the chosen porous media consists of a number of fractured carbonate core samples. Parameters such as oil recovery factor, water and oil production rates, and pressure drop along the core are recorded for both dead and live oil. According to results, at first increasing pressure improves the oil recovery, but this improvement after MMP is not as significant as... 

CO2 flooding has been recognized widely as one of the most effective enhanced oil recovery (EOR) technologies for reducing greenhouse emissions while increasing the ultimate recovery of oil reservoirs. Because of the wide variety of parameters that can influence, the outcome of CO2 storage projects reservoir simulation has gained wide popularity. In this study, a fully compositional reservoir simulation model was used to simulate various operational conditions, reservoir properties and fluid composition, and their effects on the amount of CO2 stored and oil recovered. The results can be used for selection of best reservoir candidates for carbon storage and optimization of operational... 

The use of water-alternating-gas injection can potentially lead to improved oil recovery from the fields; simultaneous water and gas injection is a form of water-alternating-gas injection. However, there is still an incomplete understanding of these processes and the need for comparative work is inevitable. Core flood experiments and compositional simulations of water-alternating-gas and simultaneous water and gas processes are presented. Immiscible, near miscible, and miscible modes of injection are covered. Matching process is done and optimization of design parameters (injection rate, slug size, water-alternating-gas ratio, and injection gas) is performed. Experimental data demonstrate...