Sharif Digital Repository

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... 

Gas injection process for more oil recovery and in particular CO2 injection is well-established method to increment oil recovery from underground oil reservoirs. CO2 sequestration which takes place during this enhanced oil recovery (EOR) method has positive impact on reducing the greenhouse gas emission which causes global warming. Direct gas injection into depleted oil reservoirs, encounters several shortcomings such as low volumetric sweep efficiency, early breakthrough (BT) and high risk of gas leakage in naturally fractured carbonate oil reservoirs. Carbonated water injection (CWI) has been recently proposed as an alternative method to alleviate the problems associated with gas... 

Thermodynamic micellization model is known as an appropriate approach for prediction of asphaltene precipitation. However, the reliability (i.e. accuracy) of this model for whole range of pressure or injected gas mole percent must be checked. In practice, the accuracy can be improved by using a suitable characterization method. In this research, a computer code for implementing the thermodynamic micellization model has been developed. Having used this program, we make the prediction of asphaltene precipitation by using data reported in the literature as well as the experimental data obtained from high pressure, high temperature asphaltene precipitation experiments under gas injection... 

Due to a large number of rich natural gas reserves in Iran, and considering the acceptable income from the exports of oil products, the consumption of gas instead of oil products in different consuming sectors seems to be rational. Therefore, in this article, the allocation of natural gas to different sectors such as residential, industries, power plants, transportation, reinjection to oil wells, export, and so forth is estimated based on the three scenarios using a linear programming method for the year 2025 in Iran. The results indicate that if there is no planned consumption management, the allocation of gas in future years will certainly have deficiencies in some sectors in Iran.... 

As the oil production from conventional oil reservoirs is decreasing, oil production through Enhanced Oil Recovery (EOR) processes is supposed to compensate for both the oil production reduction in matured oil reservoirs and the worldwide dramatic increase in oil demand. Therefore, developing a strategy to choose an optimized EOR technique is crucial to find a resolution for production decline in oil reservoirs. A screening tool recommending the most appropriate EOR method is proposed in this study. An expert fuzzy logic system is employed to screen four well-known EOR methods including miscible CO2 injection, miscible HC gas injection, polymer flooding and steam injection based on the... 

Although alkaline-surfactant-polymer (ASP) flooding has proven efficient for heavy oil recovery, the displacement mechanisms and efficiency of this process should be discussed further in fractured porous media. In this study, several ASP flooding tests were conducted in fractured glass-etched micromodels with a typical waterflood geometrical configuration, i.e. five-spot injection-production pattern. The ASP flooding tests were conducted at constant injection flow rates but different fracture geometrical characteristics. The ASP solutions consisted of five polymers, two surfactants, and three alkaline types. It was found that using synthetic polymers, especially hydrolyzed polyacrylamide... 

In the optimization of naturally fractured reservoirs, it is required to take into account their complex flow behavior due to high conductivity fractures. In this regard, the possible effects of fractures must be included in the optimization procedure. In a water-flooding project, fast water breakthrough from injection to production wells may be occurred because of high permeability fractures. To consider the effect of the fracture system, a multi-criterion optimization procedure is proposed in this work. For this contribution, Non-dominated Sorting Genetic Algorithm version II (NSGA-II) is implemented for the optimization purposes. Considering the effect of the fracture system on the flow... 

Gas-oil gravity drainage that takes place in the gas-invaded zone of fractured reservoirs is the main production mechanism of gas-cap drive fractured reservoirs as well as fractured reservoirs subjected to gas injection. Interaction of neighboring matrix blocks through reinfiltration and capillary continuity effects controls the efficiency of gravity drainage. Existence of capillary continuity between adjacent matrix block is likely to increase the ultimate recovery significantly. Liquid bridge formed in fractures has a significant role in maintaining the capillary continuity between two neighboring matrix blocks. The degree of capillary continuity is proportional to capillary pressure in... 

The Conventional Fire Flooding (CFF) process application feasibility on fractured carbonated reservoirs remained questionable. In this paper first combustion parameters and reaction kinetics of a naturally fractured low permeability carbonated heavy oil reservoir in Iran called Kuh-E-Mond applied to simulation study. After that, simulator has been validated with Kuh-E-Mond combustion tube experiment. Recovery mechanism in single block matrix is different from one in conventional model since oxygen first flows into the fractures and then diffuses from all sides into the matrix. Combustion of the oil in the fractures produces some water ahead of fracture combustion front which prohibits oxygen... 

Nitrogen has emerged as a suitable alternative to carbon dioxide for injection into hydrocarbon reservoirs worldwide to enhance the recovery of subsurface energy. Nitrogen typically costs less than CO2 and natural gas, and has the added benefit of being widely available and non-corrosive. However, the underlying mechanisms of recovery following N2 injection into fractured reservoirs that make up a large portion of the world's oil and gas reserves are not well understood. Here we present the laboratory results of N2 injection into carbonate rocks acquired from a newly developed oil reservoir in Iran with a huge N2-containing natural gas reservoir nearby. We investigate the effectiveness of N2... 

Injectivity decline due to mineral scale deposition in near wellbore region of water injection wells is one of the main challenging issues and have been widely reported in the literature. One of the main mechanisms of injectivity loss is incompatibility between injected and formation waters that may result in inorganic scale precipitation and subsequent deposition in porous media. Reliable reactive flow models to predict type and amount of scale along with permeability decline estimation allow planning and risk management of water flood projects. In this paper, we present a coupled geochemical and hydrodynamic model to simulate the scale precipitation and deposition of mineral scales in... 

Water injection into petroleum reservoirs is widely performed around the world for enhancing oil recovery. Understanding the underground fluid path is an important factor in improving reservoir performance under waterflooding operation. This may be used to optimize subsequent oil recovery by changing injection patterns, assignment of well priorities in operations, recompletion of wells, targeting infill drilling, and reduce the need for expensive surveillance activities. Most of the hydrocarbon reservoirs are equipped with sensors that measure the flow rate, pressure, and temperature in the wellbores continuously. Valuable and useful information about the interwell connections can be... 

Petroleum industry is moving toward enhancing oil recovery methods, especially water-based methods, including low salinity and smart water flooding which water with an optimized composition is injected into the reservoir for improving oil recovery. Injection of water into the target formation is also a common operation in geothermal energy production. As the water is being injected into the reservoir, pressure and temperature change along the well column and cause scale formation. Mineral scale precipitation and deposition is a common problem for water injection wells which reduces the effective radius of the wellbore and affects the injection efficiency. In this paper, modeling scale... 

Enhanced oil recovery (EOR) methods are mostly based on different phenomena taking place at the interfaces between fluid–fluid and rock–fluid phases. Over the last decade, carbonated water injection (CWI) has been considered as one of the multi-objective EOR techniques to store CO2 in the hydrocarbon bearing formations as well as improving oil recovery efficiency. During CWI process, as the reservoir pressure declines, the dissolved CO2 in the oil phase evolves and gas nucleation phenomenon would occur. As a result, it can lead to oil saturation restoration and subsequently, oil displacement due to the hysteresis effect. At this condition, CO2 would act as in-situ dissolved gas into the oil... 

In this paper, to set R&D priorities at sector level, a developed method is proposed which is combined of scenario planning and critical technologies method and then applied for prioritizing R&D issues of membrane technology in National Iranian Gas Company (NIGC). In the first phase (through 3 steps), scope of NIGC is mapped using national documents and viewpoints of experts and managers. This map includes main process of gas processing and gas conversions. Then strategic goals of gas industry including gas exports, conversions, injection and internal use, are developed. Also Strategic Technology Units (STUs) are identified and twenty distinct membrane technologies including technologies of... 

In this work, the vapour extraction (VAPEX) process is studied experimentally in a rectangular physical model at moderate-high pressure. The solvent was either pure propane or a mixture of propane/ methane with different compositions. The solvent and carrier gas were totally mixed before injection, so that a solvent with the desired composition flowed through the injector during experiments, and the solvent mixture was in thermodynamic equilibrium before injection into VAPEX cell. Effects of pressure and composition of solvent were studied. Results showed that at a fixed pressure, the process is more effective with pure solvent compared to the use of solvent mixtures. The main feature of... 

Although viability of low-salinity waterflooding (LSWF) at the laboratory scale has been proven, there are some challenges associated with its field application, which sheds uncertainties on its economic success. One of the challenges is the minimum required volume of low-salinity water, which should be injected to the reservoir due to the salt dispersion in porous media. Once the low-saline brine is injected into the reservoir, mixing of injected (low-salinity) and resident (high-salinity) brines occurs and the developed mixing zone grows continuously as the front moves from the injection well toward the production well. Increase in the salinity of the front reduces the efficiency of LSWF.... 

Optimization of the placement and operational conditions of oil wells plays an important role in the development of the oilfields. Several automatic optimization algorithms have been used by different authors in recent years. However, different optimizers give different results depending on the nature of the problem. In the current study, a comparison between the genetic algorithm and particle swarm optimization algorithms was made to optimize the operational conditions of the injection and production wells and also to optimize the location of the injection wells in a southern Iranian oilfield. The current study was carried out with the principal purpose of evaluating and comparing the... 

Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of... 

Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of...