Sharif Digital Repository

Reactive flow through porous media is a phenomenon of high importance in various study subjects i.e. groundwater, mining, geology, and petroleum reservoirs. In petroleum engineering, a related topic to this phenomenon is the dissolution of the rock matrix due to acidizing. Near_wellbore carbonate rock acidizing has been used for decades in the petroleum industry to enhance the productivity of the well. Optimal injection rate is a key question in such operations. Various models have been used to simulate reactive flow in porous media many of which are continuum-scale that face significant uncertainty regarding the pore-scale nature of the flow, mass transfer, reaction, and subsequent changes... 

MPD technique manages drilling pressure to keep bottom hole Pressure balanced in the well. The objective to this studs, is to approximate the well pressure to formation pressure to prevent entry of fluid into the well. MPD is a new method drilling in which, driller controls the annulus pressure in order prevent drilling problems. the circulating fluids system employed by MPD technology is more akin to that of a pressure vessel. In this thesis, using in laboratory-made machine, reacts with sudden changes in pressure at the bottom hole in the shortest possible time. Basically, this system is a system where well bore pressure management is obtained by adjusting the pressures along the well bore... 

In many fields, due to the lack of thickness of the reservoir layer, vertical drilling cannot be used due to low wellbore efficiency, so to solve this problem, directional and horizontal drilling is used. During drilling of highly deviated wells, to increase the efficiency of directional drilling, it should be tried to keep the path of the well completely in the reservoir layer, so that the full capacity of this type of drilling is used and the efficiency of the well is increased. To achieve this goal, Geo-Steer drilling technology is proposed in which decisions on the path of the well are made with the help of current reservoir and geological data. In this type of drilling, instantaneous... 

Poor hole cleaning while drilling due to problems such as pipe sticking and ROP reducing will increase drilling cost. It is almost impossible to optimize the hole cleaning during the well planning due to the large number of effective parameters, so it is very important to monitor the hole cleaning conditions while drilling. The best way to monitor the well condition during drilling is using the real time drilling data (RTDD). Hook load (HKL) is one of many RTDD parameters that measured at the surface during drilling operations so it can be used to evaluate the hole cleaning condition. In this research, how to process the raw data recorded while drilling has been investigated. In the next... 

Two phase flow through porous media is one of great interests which have been studied for decades in petroleum sciences and even other fields, e.g. hydrology and physics, to solve problems such as enhanced oil recovery, contaminated groundwater or CO2 sequestration projects. Flow in porous media typically predict by means of Darcy’ law which in two phase flow lead to equations such as Buckley-Leverett or Koval, but today it is well approved that compact prediction of flow pattern by these equations may be accompanied by enormous errors and it’s because flow in certain condition is fractal. In this work a new mechanistic model has been used for simulating of immiscible drainage process and... 

This paper describes the use of Quad-Tree Decomposition for upscaling of absolute permeability 2D geological models. Quad-Tree Decomposition is a data structure and generates an unstructured upscaled model that preserves the heterogeneity of the original geological model. In other words, in high-variability regions of the geological model, the gridblocks of the upscaled model remain small but in other regions that the permeability variation is low, the gridblocks of the upscaled model are coarsened. Quad-Tree Decomposition is a very simple, efficient and robust method that reduces the total number of gridblocks and results to high saving in time and memory required to flow simulation in the... 

One of the major problems in directional and extended reach wells is poor hole cleaning. Directional and horizontal drilling is more complex than vertical wells. Ineffective particles transport leads to several undesirable issues during drilling. This thesis analyzed all parameters which have directly affected directional hole cleaning. The thesis is based on an experimental set-up designed in Sharif University. In the experimental work, two types of drilling fluid, Newtonian and Non-Newtonian with numerous rheological parameters, three different flow rate, three various nozzle sizes and three individual RPMs in three distinct inclinations 30°, 60° and 90° were used to simulate. Also, to... 

Gas-Assisted-Gravity-Drainage (GAGD) is a new enhanced oil recovery method which utilizes the natural tendency of gas and oil to segregate due to gravity. Higher recovery of GAGD, compared to continuous gas injection (CGI) and Water-Alternating-Gas (WAG) makes it the focus of researches in recent years. This work is trying to propose a surrogate model based on Artificial Neural Networks for GAGD process. The proposed model should be able to mimic the behavior the process in a short time in order to be used as an alternative computationally expensive simulator where a large number of simulations are needed, such as sensitivity analysis, optimization of the process, or risk analysis. A... 

Many petroleum engineering operations, such as drilling, well completions, and workover, may cause an alteration in the properties of hydrocarbon-bearing formations, including porosity and permeability. Solid and fluid influx into the reservoir in an overbalanced pressure condition can cause permeability reduction from formation damage in the invaded zone. While the solid invasion is limited to a few inches away from the wellbore, the fluids will invade significantly deeper into the formation. Therefore, the invasion of fluids may be considered as the primary mechanism that causes the near-wellbore damage. Correct quantification of the damage is an important component for predicting well... 

Investigation of reservoir performance and long-term production prediction are main goal of numerical simulation. Numerical simulation mainly consists of solving sets of non-linear equations developed by combination of continuity equation, equation of state and Darcy equation. Classical methods such as finite difference method (FDM), finite volume method (FVM) and finite element method (FEM) are widely used for solving sets of fluid flow equations that mentioned above. Researchers have used other methods like boundary element method recently. Each of these methods has their own restrictions. But the main source of error in these methods is due to numerical estimation of spatial derivatives... 

This paper presents finite-element simulation results for hydraulic fracture’s initiation, propagation at reservoirs with damaged zone and naturally fractured reservoirs that likely finds in Iranian oil fields. To address this objective, a two-dimensional poro-elastic model was solved and cohesive zone modeling was used as the methodology for simulation fractures. This enables us to assign individual criteria for fracture initiation and propagation in each model. Our results demonstrate that hydraulic fracturing is not useful in reservoir with strongly damaged zone around the wellbore, because pore pressure increases at that zone and plastic flow of fracture wall happens, so it is better to... 

Problems with the mitral valve can make the heart less efficient at pumping blood around the body. Severe problems can lead to heart failure if the valve is not surgically repaired or replaced. A simple approximation of the heart geometry is used and the valve dimensions are based on reported measurements. The primary objective for this study is to design and simulate the opening and closing behavior of the mitral valve using 2D fluid-structure interaction (FSI) model using ADINA software in order to evaluate and investigate the hemodynamic performance and problems of mitral valve, in which the blood is described as a viscous incompressible fluid, and the mitral valve is described as an... 

Fracture reservoir modeling is an important subject since a lot of oil and gas resources around the world are preserved in them. One of the enhanced oil recovery methods in these reservoirs is gas injection and especially CO2 injection because of environmental issues. In one part of this research, a new diffusion mechanism called “double cross-phase diffusion” is introduced and applied to simulate the non-equilibrium gas injection process into fractured rocks. This new mechanism represents additional multicomponent gas diffusion into the crude oil through the water phase, existing in porous media as initial water saturation. Therefore, a lab-scale simulator, by implementing the generalized... 

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... 

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... 

During the drilling process, cutting concentration in vertical and inclined wells is a common problem and major issue in designing hydraulic parameters. This is becoming more important in near bit area. Cutting transport usually is affected by several parameters such as mud rheology, flow rate, nozzle size, rotation speed, and mud weight.
In this work it was aimed to design a new set-up to test all the factors on hole cleaning phenomenon especially in near bit area. The set-up consists of a 16 feet long flow loop, 3.28 feet height of the test section, and 3.33 inches inner diameter of the test section. Each parameter which has an impact on hole cleaning could be varied. The cutting... 

One of the best stimulation methods for oil and gas wells is matrix acidizing in order to increase the near wellbore permeability. in acidizing, good acid coverage in different layers is one the main goals. so, various methods have been presented. important part in using these methods is to not damage formation and economic matters. modern methods utilize VES acids for this purpose. viscoelastic characteristics of these materials by formation of miscellaneous, increases the apparent viscosity by a large degree. for this reason, VES fluids can be used to improve acid divergence in acid injection operation. acid system based on viscoelastic surfactants that is changed to gel instantly, can be... 

In this study, the green element method is used to model petroleum problems such as oil production due to expansion mechanism, one and two dimensional spontaneous imbibition and water flooding. Despite of boundary element method that its applications in reservoir engineering are limited to simulation of single phase fluid flow in homogenous media, green element method can solve multi-phase flow in heterogamous media. In this thesis, by this method the governing partial differential equation for these processes are modeled and then solved. In one dimensional medium, green element method can successfully simulate the oil production from heterogamous reservoir due to expansion mechanism. The... 

In this work, a basic model for numerically simulating matrix acidizing in carbonate formations is developed. This model employs laboratory linear acid core-flooding data and avoids any fitting parameters. Wellbore-scale numerical simulation is based on finite-volume method with Cartesian coordination and cubic meshing. Mass transfer equations are based on fluid front tracking and the momentum transfer equation is the Navier-Stokes equation for flow in porous media. The effect of fine-scale dissolution phenomena of carbonate rocks are translated into the coarse-scale by homogenization. In this work, it is tried to achieve a simple but logical approach towards a correct simulation, avoiding... 

The purpose of this research is to model transport and separation of single and gas mixtures through pore network modeling in dense membranes. In the first part of the project, the mass transfer and governing mechanisms of transport are investigated. In the second part of the project, simulation of membrane pore network in 3D of Cartesian coordinate is done. In the third part of the project permeability of single gas and ideal selectivity of binary gases for an actual membrane by desired mechanism are calculated. Then the results of pore network modeling were compare with the results from molecular dynamic simulation for single gas in polyurethane membrane with reasonable agreement. In this...