Sharif Digital Repository

Many of oil reservoirs in Iran that are fractured, do not have high Recovery Factor (RF), therefor Enhanced Oil Recovery (EOR) methods are exerted in them. In fractured reservoirs, due to high capillary pressure in matrix and low amount of it in fracture, the wetting phase tends to imbibe to the matrix from the fracture. Altering the wettability of reservoir rock from Oil-Wet (OW) to Water-Wet (WW) enables the injected water to imbibe to matrix and sweep its oil. Also reducing oil/water IFT turns oil to small droplets, helps them to pass narrow pores and be produced. In one of the new EOR methods called chemical EOR, chemical additives are injected to the reservoirs along with water to... 

Well stimulation techniques are used to increase the productivity of oil and gas wells. One of the effective well stimulation methods, is matrix acidizing. During matrix acidizing, acidic solution is injected into the formation at pressure below the formation fracture pressure. Most of the time, acid needs to be reached to low permeability layers for more efficient damage removal. Divertors are used for diverting acid from high permeability to low permeability layers.Successful performance of a viscoelastic acid during an acid job, is highly dependent on the surfactant rheological properties. For a betaine viscoelastic surfactant, we have studied the effect of different parameters on the... 

Surface Active Agents/surfactant have a strong tendency to adsorb at the interface between two immiscible fluids, due to the existence of hydrophobic portions in their molecules’ structure. Accumulation of these molecules on the liquid interface changes the intermolecular forces and causes the interfacial tension to decrease. Production of drops of the same size at a specified rate and controlling their movement’s speed are among the most important factors effective in the efficiency of processes associated with liquid drops, which could profoundly be influenced by the presence of a small amount of a surface active agent. In this study, the effects of surface active agents on the growth,... 

Enhanced Oil Recovery (EOR) techniques have become of the main priorities of the oil industry during the high oil price era. It is interesting to note that the common method to increase production from reservoirs is the water injection method, which recovers a very low amount of oil from the oil-wet matrices due to the lack of water imbibition. Previous studies have shown that changing the wettability of rock would critically increase the oil recovery efficiency. This could be achieved by the low-salinity water injection method. In recent years, extensive studies have been conducted on this technique to evaluate its effectiveness for various types of oil reservoirs. Simultaneous injection... 

During all operations in hydrocarbon reservoirs, there is a possibility of formation damage. These damages can reduce the production of fluids from reservoir. One of the major damages that can seriously affect the performance of a reservoir is the damage caused by drilling fluid. The main purpose of this research is to study the main mechanisms of formation damages when using oil-based drilling fluids and fixing or preventing these damages. Once the mechanisms are identified, it is tried to cure the damages but without acid-washing. The alternative method is surfactant-washing which is a surfactant-brine injection. This injection has been done for the first time. This study helps to industry... 

Naturally fractured oil reservoirs represent over 20% of the world's oil reserves, while over 60% of the world’s remaining oil lies trapped in fractured reservoirs. However, relatively little success has been achieved in increasing oil production from these complex reservoirs. Water flooding process leaves much oil in the reservoir, especially in fractured reservoirs. Surfactant flooding is known to lower the interfacial tension and hence, reduces capillary forces responsible for trapping oil and increasing recovery. However, fundamental understanding how the fracture geometrical properties affect the oil recovery efficiency during surfactant flooding remains a topic of debate in the... 

One of the suitable methods in EOR processes is miscible and immiscible gas injection. By gas injection, it is possible to replace all the oil, which is in contact with the gas. However, reservoir heterogeneity, low density, and low viscosity of gas result in problems such as gravity segregation, and fingering and consequently the gas reach the production well without any significant contact with reservoir oil. A way to deal with this problem is gas injection in the form of foam. In fact, gas injection in this manner increases the oil production by decreasing gas mobility and the negative effects of reservoir heterogeneity on gas displacement. Foam stability has a key role on the efficiency... 

Chemical flooding such as surfactant flooding in oil reservoirs can change the wettability and interfacial tension between oil and water and so reduce the residual oil saturation in the reservoir. Some of these materials can be adsorbed a lot on the surface of carbonate rocks, so it is difficult to predict the oil recovery factor in such process. Therefore it is necessary to survey the adsorption amount of surfactants in chemical EOR injections.In this thesis, the adsorption of a nonionic surfactant on the surface of carbonate rock is experimented and the proper model is obtained. Then the surfactant is injected in a core saturated with oil to observe the efficiency of this surfactant in... 

Today, due to limited number of light oil reservoirs, enhanced recovery from heavy oil reservoirs is taken into consideration. During the early production from heavy oil reservoirs, due to high viscosity, only a small amount (about 5%) of the oil can be produced; also after water injection operation due to unfavorable mobility ratio of water and oil, sorely more than about 10% of the original oil can be produced. On the other hand, fractured reservoirs represent about 20% of the world's oil reserves, while over 60% of the world's remaining oil reserves are in fractured reservoirs. Water flooding process leaves very high amounts of oil as remaining oil in these reservoirs too. One of the... 

Application of nanotechnology in the field of heat transfer has increased recently. The need to increase heat transfer rate yet decrease the size of cooling equipment, brought about lots of attention to thermal properties of Nanofluids. Nanofluid is the suspension of nanometer-sized solid particles in base liquid. Research on convective heat transfer of nanofluids which is only two decades old, shows great potential in increasing heat transfer rate. Although there is a remarkable research on thermal conductivity of Nanofluids, negligible research was conducted on combined Nanofluids . Developed Theory for thermal conductivity of combined nanofluid can be used to modeling the thermal... 

Always, understanding the properties of crude oil and related phenomena of that has been noticeable matter. Surface tension is one of the important fluid properties and the evaluation of that is essential in oil industry especially in enhanced oil recovery method (EOR) and transport of crude oil by using emulsions.
In this research, interfacial tension (IFT) was measured via pendant drop method. The effect of three parameters was investigated on IFT for creating of stable oil/water emulsion. These parameters were temperature, concentration of surfactants, and salinity. They were varied between 25-65 ᵒC, 0.05-0.2 gr and 5000ppm respectively. It was used two types of surfactant; acid... 

The aim of this research is to study the effect of surfactant type and the concentration reactants on the size, shape and magnetic properties of iron-gold core-shell magnetic nanoparticles (NPs) useable for biomedical application. The reverse micelle procedure was employed to synthesize iron NPs using two surfactants of CTAB and SDS. A gold shell with a thickness in the range of 10 to 40 nm was induced by reverse micelle method in order to prevent oxidation of the iron core. The size and morphology of NPs were studied by transition electron microscopy (TEM). It was found that the size of NPs increases by the increasing the reactants concentration while the morphology of the NPs was not... 

Nowadays, due to limitation of production from conventional oil reservoirs, enhanced recovery from heavy oil reservoirs are of great concern. In heavy oil reservoirs, only 5% of initial oil in place (IOIP) is producible due to high viscosity. Water flooding increases oil recovery just up to 10% which is due to improper mobility ratio. One of popular methods for increasing oil recovery is injection of chemical materials. Chemical methods are used in reservoirs that have high degree of heterogeneity like heterogeneous and layered reservoirs. These heterogeneities cause diversion and loss of injected water which leads to remaining of oil in its place. Using surface active agents, as a popular... 

In the modern societies, wastewater treatment is essential in achieving high level of standard in environmental protection and disposal. Recently, many researches are performed to study the surfactants’ biological decomposition in wastewater treatment process. In this project, fixed bed aerobic reactors are used in order to remove surfactant from wastewater. Integrated fixed film activation sludge reactor (IFAS) is used to remove surfactants and organic matters. It also used to study the capability of micro organisms in organic load removal in fixed bed biofilm for biological treatment of industrial wastewater. Pumice stone were used as the support in the reactor. The pumice stone is a... 

Understanding the properties of crude oil and the phenomena arising from this precious matter has always been of considerable importance. One of these important phenomena is emulsion, which is well-known in a great number of crude oil-related processes such as drilling, well completion, production, transportation and even the processing units in the refinery. One of the most important properties of crude oils and their emulsions is their flow or in other words their rheology. Therefore, in this project has also been tried to investigate the rheological behavior of crude oil and water in crude oil emulsion, experimentally and theoretically. The experiments were carried out using two crude... 

One of the most important EOR methods in oil reservoirs is surfactant and polymer flooding. Surfactants cause decreasing in interfacial tension between oleic and aqueous phases. However, polymers give us efficient mobility control in displacing oil by increasing the viscosity of aqueous phase. Therefore, oil is displaced in aqueous phase by viscous forces.
One of the most important challenges in surfactant flooding is adsorption. The net surface charge distributed on the rock surface depends strongly on pH. When we inject surfactant in reservoir, electrostatic charge on rock surface causes the first-layer adsorption. After that we have had second-layer adsorption.
In this thesis we... 

Surface phenomena is one of the fundamental branches of science that has many applications in industries related to multiphase processes. One of the most important issues of this knowledge is inter-phase transport phenomena in contacting gas - liquid and liquid – liquid systems. Multiphase systems generally include dispersions such that in many cases are associated with the relative motion between the continuous and dispersed phase. One of the most widely used inter-phase flow systems is dispersion of gas bubbles in the bulk of liquid. The overall efficiency of these systems is often determined by the characteristics of the gas phase. In order to understand the dynamic behavior of such... 

Surfactants are widely used in enhancing oil recovery. But application of worm-like micelles which seem to be a perfect candidate for enhancing heavy oil recovery have been less studied despite their significant ability in reducing interfacial tension and their high viscosity. This research consists of three parts. In the first part, the kinetic and equilibrium adsorption of surfactant on reservoir rock is experimentally investigated, and its appropriate kinetic and equilibrium adsorption model is specified. According to the adsorption models, the pseudo second order kintic coefficient of adsorption is proved to have a linear relationship with concentration, so its value at different... 

Matrix acidizing operation is one of the popular methods of well stimulation in the oil and gas industry which is used to remove near wellbore damage, increase the permeability, hence improve the production rate from the formation. Hydrochloric acid is used in the carbonate reservoirs to remove formation damage and create wormhole deep in the rock. It has been shown that with the proper operating design, significant improvement in the production rate can be obtained. A successful acid operations involves the proper selection of the candidate wells, identify the type of formation damage, stimulation method selection, correct design acidizing scenario, implementation of the technique and... 

In this experimental work terminal velocity, velocity profile and aspect ratio of bubble with 1.49 mm diameter which ascend in pure water and infected by surfactant nonionic C10DMPO and surfactant ionic SDS in regime that surface tension is dominant, have been considered. Observations showed that with respect to entering nozzle, bubbles with this diameter have two initial stable shape; spherical and extended form on surface for horizontal needle and vertical nozzle. Results are (1) Bubbles with initial spherical shape had lower terminal velocity and higher aspect ratio with respect to bubbles with initial extended form, (2) Spherical bubble had aspect ratio about 1 at whole bubble column...