Sharif Digital Repository

Permeability is an essential parameter used for reservoir evaluation, simulation and management to optimize oil recovery. The conventional approach to estimate reservoir connectivity, conductivity, sweep efficiency and other critical information for decision-making is to build detailed geological models, which are then upscaled to a coarser grid where flow simulations are run. However, this takes many hours to be carried out even for a single realization practically. In practice, a very small number of realizations are considered and consequently the true uncertainty in the results is very poorly estimated. In this study, a statistical model of isotropic overlying sandbodies is used to... 

Accurate prediction of relative permeability for various reservoir rocks at various saturation conditions has been of concern for a long time in petroleum industry. Relative permeability is known as one of the most significant parameters in simulation of actual multi-phase flow through porous media during life-time of a hydrocarbon reservoir. In addition, it plays important role in oil production and well completion. Direct experimental measurement in order to determine relative permeability of porous rock has long been recorded in petroleum related literature. However, empirical methods for determining relative permeability are becoming more widely used, particularly with the advent of... 

Because of a lot of water, gas and polymer injection processes in industry, two phase flow simulation is very useful. So performing experimental work to find out fluid flow behavior in a small scale of reservoir has special importance. The results in various scales will differ because of heterogeneity and different dominant flow regimes. To see this effects, comparison of two small scales, namely core and micromodel scales, has been studied using the scale up methods. In literature review, the scale up procedure, relative permeability methods and dimensionless numbers in two phase flows has been described. Here the relative permeability and oil... 

Imbibition process is known to be an important recovery mechanism in naturally fractured reservoirs with water-wet matrix blocks that are imposed to water influx from an active aquifer or water flooding. Matrix blocks which are subjected to water flooding or water invasion from active aquifers do not become immersed in water at once, but they experience gradual rising of water in fracture. But most of imbibition studies are performed under conditions of totally immersed cores in static aqueous phase. Surfactants are known to reduce residual oil saturation by decreasing interfacial tension (IFT) between oil and water. On the other hand, considerable reduction of IFT due to surfactant... 

Fractured reservoirs contain about 85 percent of oil reservoirs and 90 percent of gas reservoirs in Iran. Full study of fractures as the main factor in fluid flow seem essential for these reservoirs. Recently a stochastic method based on the assumption that the elastic energy in the fractured media follows a Boltzmann distribution is proposed. The method utilizes an elastic energy function that sums the interactions of all pairs of fractures present in the model. The energy for each pair depends on the distance between the two fractures, their orientations, lengths and some other elastic medium properties. This objective function used in simulated annealing algorithm for generating fracture... 

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... 

In this research oil production decline curve of heterogonous reservoirs was investigated. Heterogeneity is modeled by percolation theory and using Petrel software and mass balance equations are solved by Eclipse simulation software. In primary production stage which oil flows up the reservoir spontaneously by reservoir high internal pressure, decline curve is exponential. Changes in the characteristic parameter of the exponential decline curve with occupation probability and permeable objects size were investigated.In secondary production stage, after reducing the natural production potential of the reservoir, water injection is used to increase and stabilize the pressure and increase the... 

Increasing the global demand for energy and decreasing the production rate of oil reservoirs have forced the oil companies to focus on enhanced oil recovery (EOR) extensively. This paper summarizes the design, reservoir simulation, and results of different gas injection scenarios in one of the Iranian complex oil reservoirs. This complex reservoir is located in the south west of Iran and is made up of sandstone, limestone, and dolomite layers. It is an under saturated reservoir with no gas cap but with a strong aquifer. Oil production has started in 1977, but due to strong aquifer the production is still in the plateau period. In this study, by simulation, it is estimated that natural... 

The most common method of oil recovery is by displacement. By injecting water into wells, to push the oil to production wells, ultimately, the injected fluid breaks through at the production wells. Estimation of breakthrough time is important for the reservoir engineering calculation and the prediction of enhance recovery scenarios. Oil reservoirs are extremely complex, containing geological heterogeneities on all length scales which have a significant impact on hydrocarbon recovery. The conventional approach to investigate the reservoir performance is to build a detailed geological model, upscale it, and finally run flow simulation which is computationally very expensive. In... 

In imbibition process, as one of the main mechanisms of recovery from naturally fractured reservoirs, a wetting fluid enters matrix blocks and produces nonwetting phase from blocks as result of interaction between capillary, gravity and viscous forces. Depending on various characteristics of system different types of imbibition like counter-current spontaneous imbibition, cocurrent spontaneous imbibition and dynamic counter-current imbibition could occur. In order to predict recovery from matrix blocks scaling equations can be used. In this thesis suitable scaling equations are presented for different types of imbibition by using analytical solutions. The studies cases are counter-current... 

In fractured reservoirs under the gravity mechanism, the oil transfer between the matrix blocks is affected by mechanisms such as capillary continuity or re-imbibition. Capillary continuity between adjacent matrix blocks can be created by formation of liquid bridges, or physical contact of surfaces due to the roughness of the fracture wall surface.Since the presence of liquid bridges can be effective in creating capillary continuity and therefore the amount of oil production, the study of the presence of liquid bridges between matrix blocks and how they change in terms of volume and shape in the process of oil and gas movement is of particular importance. Although there are studies on the... 

The structure of a Pore and how The Pore and grains are distributed in it have a significant impact on the amount of fluid recovery and its production. In this research, the effect of the structure of the porous medium on the relative permeability curve and the amount of fluid recovery has been investigated, and 3 realistic, simplified and homogeneous models have been selected for this work. The simulation is that carbon dioxide gas is injected into an environment completely saturated with water. This work has been done in a water-loving environment and by examining three wettability levels of 30, 60 and 75. Simulation of fluid flow has been done in COMSOL software at the Pore scale. The... 

The most fundamental concept in considering electrical properties of reservoir rocks are formation Resistivity factor and Resistivity index which are defined by Archie and are useful in interpretation of well logging, evaluation of porosity and saturation. A theory on the relationship between formation resistivity factor and porosity, also resistivity index and saturation are presented by use of parameters Cementation factor and Saturation exponent. The Archie equation is valid only when the rock is strongly water-wet and clay free, which is not the case in carbonate rocks. Therefore the Archie equation cannot be generalized over the entire carbonate reservoirs. On the other hand influence... 

VAPEX is a relatively new EOR process for the recovery of heavy oil. In this process solvent is used to form a vapor chamber within a reservoir. Vapor dissolves in the oil and diluted oil drains by gravity to a horizontal production well. The essential features of this recovery mechanism have been discussed in this study. Furthermore, a semi-analytical and a simulation study of VAPEX process have been performed on a specified Iranian heavy oil reservoir (such as Kuh-e-Mond). The aim of this study is to investigate an exponential functionality (correlation) witch incorporates all physical parameters that affect the production rate of VAPEX process in dimensionless form. The adjustable... 

Thermodynamic modeling is a useful method for predicting of asphaltene precipitation due to various reasons, such as CO2 injection, mixing of different oils in oil storage and pressure changes. However, the application of solid model and thermodynamic micellization model, for prediction of asphaltene precipitation under gas injection condition, hasnot been improved. In this work, two computer codes which are based on two different asphaltene precipitation thermodynamic models, 1-Thermodynamic Micellization Model and 2- Solid Model, have been developed, and, used for predicting of asphaltene precipitation data reported in the literature as well as the experimental data obtained from high... 

Today, due to a massive increase in accuracy of reservoir characterization models, multiphase flow simulation on real permeability fields faces a serious challenge. Using multiscale methods in reservoir flow simulation of a heterogeneous environment has led to huge speed-up of the simulation. In multiscale methods, instead of replacing a heterogeneous medium by an equivalent homogeneous medium, used in upscaling, the problem is solved on the original resolution. In this thesis, multiscale finite volume method (MSFV) has been used to simulate flow and saturation behavior of a black oil model. Unlike the original multiscale finite volume methods that were unable to solve compressible fluid... 

Characteristic of the reservoir, including the important discussion in the oil industry, is widely practiced in the modeling, simulation and EOR. One of the methods fordetermining the specifications of the reservoir is geostatistical technique. This means that a large number of realizations of the reservoir model to assess the uncertainty in reservoir descriptions of performance predictions should be made.However flow simulation of all these realizations is very difficult due to cost and time calculations.To mend the problem, we use ranking realization that finally a minor number of realizations are selected and flow simulation is used to them.In this project, we use streamline simulation to... 

Most of petroleum reservoirs of Iran are fractured reservoirs which has different properties, geometrical structure and drive mechanism in comparison with conventional reservoirs. The major difference is the existence of interaction between fractures and matrix respectively with a high and very low permeable (or imperable) medi. One simulation method for these fractures is discrete fracture network (DFN) modeling which is used in this study to investigate dynamic properties of these fractures. In this study, matrix is assumed as an impermeable media then dynamic properties like effective permeability of fracture network for different realization reservoirs are calculated and and evaluated by... 

The static and dynamic properties of a porous medium are highly dependent on its internal geometry. CT scan images are used to obtain porous media geometry. These images are not directly suitable for computational purpose. Because these images are not easy computable, the pore-throat network models are used to geometrical conversation. Extracting these models from CT scans is done using statistical-probabilistic methods based on image processing. In this study, new methods for extracting the 3D pore network model from 2D/3D CT scan images and pore connection detection are presented. In this method, the geometric static parameters of the rock, including the porosity, the porosity-based...