Sharif Digital Repository

There are a lot of Fractured reservoirs around the world that have large portion of oil production. These reservoirs have complex structure and fractures have important role in production but the remaining oil in matrix causes that the oil recovery decreases. One of the most important factors in these reservois are wettability. Because most of the fractured reservoirs are oil wet and water injection process in these reservoirs are not effective and chemical EOR methods such as surfactant flooding method is used. Surfactant improve oil recovery by two reasons: 1- reduction of interfacial tension between oil and water . 2-Wettability alteration of matrix. The porpose of this project is... 

In this work the effect of composition changes of the injection gas (Hydrocarbon gas + carbon dioxide) on Water Alternating Gas (WAG) performance in immiscible flooding which has been rarely attended in the available literature is investigated. Core flood experiments are conducted on a 10 cm length Sarvak sandstone core sample at 46 degree C and at immiscible condition, i.e., below the minimum miscible pressure (MMP) of the oil sample using pure CO2 as injected Gas.The influence of injection WAG ratio on oil recovery also is investigated. Artificial injection brine which is made by dissolving NaCl into distilled water with 5000 ppm (mg/L), NaftShahr oil which has about 41 API gravity and... 

Scale deposition is one of the reasons of formation damage during water injection process. This phenomenon often ocuures when two incompatible waters that interact chemically and precipitate minerals, mix within the reservoir. A typical example is sea water, with high concentration of sulfate ion and formation water, with high concentrations of calcium and/or barium ions. Mixing of these waters, therefore, can cause precipitation of calcium sulfate and/or barium sulfate. This study was conducted to investigate the permeability reduction caused by deposition of calcium and barium sulfates in carbonate cores from mixing of injected sea water and formation water in two flow rates and two... 

One of the most important production mechanisms of fractured reservoirs is wettability alteration. Since most fractured reservoirs are carbonate, and thus are often oil-wet; production of these reservoirs is facing their special challenges. Since most of our country reservoirs are fractured carbonate type, determination of the exact mechanisms of their production is necessary. Thermal EOR methods traditionally have been welcomed by big oil companies. Also, these methods of enhanced oil recovery techniques, have a much greater share in the production history of all EOR methods, rather than other EOR methods. Exponentially decreasing of oil viscosity on heating, is the main reason for using... 

Mineral scale precipitation and carbonate rock dissolution are among the most important reactions that usually occur during water injection in oil reservoirs. These reactions happen due to incompatibility between formation water and injection water as well as deviation from equilibrium conditions. These reactions must be considered precisely because of the fact that they result in variation of reservoir porosity and permeability which affects recovery factor. In this study, the effect of injection pressure on these variations during single-phase water flooding is examined accurately. Additionally, the changes of ion concentration and the amount of dissolved or precipitated calcite or... 

The objective of this MSc. thesis is to study the impact of the reactive method and the enhanced reactive method on enhancing the exploitation efficiency of Iran's offshore oil reservoir. This is achieved by enhancing production and the recovery factor of the reactive methods with respect to the currently used proactive method. Unlike the currently used proactive method that implements a fixed rate injection strategy, in this MSc. thesis water is injected to reservoir with multi-rate for the pressure stabilization of the reservoir. In order to scale up this strategy, the ensemble Kalman filter is used to frequently update the reservoir mathematical model using the available measurements from... 

The present article studies the isothermal and non-isothermal water injection into naturally fractured oil reservoirs by numerical simulation. The fractures in naturally fractured reservoirs can possess different characteristics. In addition. a remarkable number of naturally fractured reservoirs contain relatively heavy oils that could not be extracted economically; hence. the thermal recovery methods are extensively used for these reservoirs. Hot water injection is one of the thermal recovery methods that has not been explored enough compared to its alternatives. In this study. the effectiveness of the hot water injection over the cold (isothermal) water injection in oil production is... 

Low salinity water flooding (LSWF) as an efficient enhanced oil recovery (EOR) technique is proved to affect both, fluid-fluid and rock-fluid interactions to potentially release the trapped oil from the porous rock. Despite more than one decade of extensive research works on the low salinity water effect (LSWE), there are still many parameters to be studied for very complex cases. Therefore, in the first part of the experimental study of the dissertation, a systematic investigation on the effect of the initial wetting state (water-wet or oil-wet) of pure calcite is conducted to study the importance of fluid/fluid and fluid/rock interactions for LSWE investigation. In the case of initially... 

Low salinity water injection is one of the new and important methods of enhancing oil recovery. Experimental studies show the fact that the change in water salinity affects the interfacial properties of water-oil (Fluid-fluid interactions) And the change in wettability that represents the porous media (Rock-fluid interactions) is effective for Oil-recovery. Recently, progress have been made in simulating the process of injecting low-salinity water into the field or core dimensions. However, the simulation of the low salinity water injection process has been much less studied considering the fluid / fluid and fluid / rock interactions at the pore scale. The purpose of this study is to... 

Enhanced oil recovery (EOR) techniques are gaining more attention worldwide as the proved oil is declining and the oil price is hiking. Although many giant oil reservoirs around the world were already screened for EOR processes, the main challenges such as low sweep efficiency, costly techniques, possible formation damages, transportation of huge amounts of EOR agents to the fields especially for offshore cases and the lack of analyzing tools in traditional experimental works, hinder the proposed EOR process.It has been shown that recently, nanoparticles are attractive agents to enhance the oil recovery at the laboratory scale.
In this study TiO2 nanoparticles were used to improve... 

Water flooding is known as a common method to maintain reservoir pressure/enhance oil recovery. The major problem in this process induced from inorganic deposits that caused formation damage around wellbore region. It is due to incompatible nature of injected and formation water which results in permeability reduction and well productivity decrease. Solving this problem is an important issue in the petroleum industry. BaSO4, CaSO4 and SrSO4 are inorganic sediments formed in this process. The physical model of water transport in reservoir and scaling damage due to sediments contains at least two dominant parameters; the kinetics coefficient that specifies the velocity of chemical reaction,... 

Water injection is known as one of the most efficient and affordable techniques to displace the oil in the reservoirs. To increase oil recovery efficiency through water injection operation, recently low salinity water injection or water containing a certain amount of effective ions (engineered/low salinity water) is proposed. Besides, improving this technique is also adopted in the oil industry using certain chemicals like surfactants to change the interfacial tension or rock wettability for more oil recovery. In order to study and model the mechanisms involved during surfactant flooding, molecular dynamics simulation is utilized here as a novel technique. The advantage of this method over... 

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...