Sharif Digital Repository

One of the major issues raised in the numerical models is the effects of various input parameters on the model output. Identifying the most important parameters in the output is very important in petroleum engineering, especially in tuning equation of states and history matching. Screening the most important parameters from unimportant parameters is assessable by sensitivity analysis.In this study local and global sensitivity analysis methods are used to identify the most important parameters in tuning EOS for seven different fluid samples. Global sensitivity analysis methods are more successful in correct ranking of tuning parameters. Morris method as a global method can screen the... 

The technique of geosteering has been widely adopted within the petroleum industry for proper wellbore positioning through involving predicting the geology ahead of the bit, furthermore, the advantages of this technique became more pronounced as drilling environments became more complex. the fundamental concept of geosteering is to put and maintain the well within the target zone(s), so as to promote safe and economical production of the well. Geosteering-related technologies, like downhole information-gathering tools and real time data transmission and data analysis applications, are continuously and significantly improved to support geosteering decisions.This study demonstrates how the use... 

The efficiency of acidizing operation is usually assessed through Build up or Drawdown test (calculation of skin). These methods are performed only after the acidizing operation, so it is impossible to evaluate the efficiency of acidizing during the real time operation. Analysis of the acidizing efficiency during the operation by using the acidizing operation data is a viable approach to this costly and challenging process. In this project, it has been tried to present a well testing method for calculating changes of skin value of a carbonate reservoirs during acidizing operation by using the real field data (surface pressure, injection rate and etc.).
The estimation of skin changes... 

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... 

In drilling the percolation structure reservoirs (such as offshore Channelized reservoirs), one of the most important factors in the effectiveness of wells is drilling permeable areas (Channels), while Channel constraints make it possible for two wells to collide. On the other hand, if the desired reservoir is an offshore reservoir, these restrictions have been increased because usually several wells are drilled near together from one platform. Therefore, proper well collision analysis method is also important in these situations. In this project, anti-collision analysis is performed using the MWD device error model between two or more wells in a static reservoir model with channel... 

In this study, for investigation of water salinity effect on asphaltene modeling, PC-SAFT equation of state has been used. All steps of modeling have been done by C sharp programming language software. Nghiem model has been used for modeling of asphalting pure solid. In this model, the heaviest component is split into two precipitating and nonprecipitation parts that their physical properties are the same in each part. Furthermore, to determine the exact mechanism of asphaltene precipitation, an oil model (Asphaltene+heptan+tuloene) in the presence of different water brine such as synthetic brine (with MgCl2, CaCl2, and Na2SO4 salts), seawater) ten and two times diluted), and formation water... 

Since the early 90s, nanotechnology has contributed to several developments in a wide range of Science and industry such as medicine, Physics, Chemistry, Aerospace, electronics and Biology. In recent years, nanotechnology has also made development in the oil and gas industry. The drilling fluid is already one of the most important parts in drilling operation.The physical properties of a mud, rheological properties and minimize fluid invasion into the formation with perfect mudcake are important to assist in optimizing results. Nano-materials as one of the achievements of recent years are effective in achieving these purposes. To obtain the above properties, a variety of polymers as... 

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... 

The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between... 

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... 

Alavand Oil field is located 50 Km away from west of Siri Island and includes DPG and DPH platforms. The production from Alavand field started in 1998 and till now 11 wells have been totally drilled .Since a production peak in 2001, the oil production in Alvand field has decreased. Water cut is increasing and reservoir pressure is decreasing gradually. Considering poor reservoir characteristic of this reservoir, productivity indexes of wells are relatively low. In addition; natural depletion of reservoir caused the wells to be unable to flow naturally and either closed or produce periodically consequently. To increase production and extend the lifetime of Alvand field, it is decided to start... 

One of the three fundamental methods in reservoir evaluation is coring, other two methods are logging and well test. Coring is an operation during which, samples from formation rock are taken, and used for laboratory tests and examinations. Although coring presents exact information from reservoir rock, its small scale is the reason of some laboratory errors. This operation is fulfilled with special bits. Coring importance shines where it could give us an idea of reservoir conditions; however cannot be develop it, to all of the reservoir. Coring is used to identify rock properties like porosity, permeability, wettability and fluid properties like fluid density or fluid saturation. Rock... 

The main responsibility of a primary cement job is to provide hydraulic isolation between various zones. Cement-sheath evaluation is concerned with the question of whether zonal isolation exists. Cement Evaluation Logs are used to evaluate the quality of cement sheath behind the casing or liner after cement job. these logs are a part of well integrity logs. Cement Evaluation Log results are complex and can be misunderstood, and it can lead to bad decisions that could have severe consequences. Cement evaluation logs must therefore be interpreted by experienced professionals. To help these interpreters, we propose a system for automatically interpreting cement evaluation logs, which they can... 

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... 

Today, with the reduction of world oil prices and the development of competing energy sources, fossil fuels such as nuclear energy, electricity, wind, etc., in order to increase the economic efficiency of oil sales, we must Reduce production costs to a minimum. If the components of oil extraction costs are examined, the cost of drilling production wells is one of the main economic components that affect the cost of producing oil. Therefore, according to the above explanations, the cost of drilling wells should be reduced.To reduce the cost of drilling a well to be drilled, it is better to predict the drilling parameters (for example ROP) before starting the drilling process. For this... 

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... 

One of the most important issues in modeling and simulation of reservoirs is determination of different rock types or Rock Typing. In this study, after a brief review of some conventional methods for rock typing, their capabilities have been investigated. In this way, for the first time, pore network modeling is used as a tool for validating the rock typing methods. By using flow simulation in porous medium with pore network modeling approach, similar rock types data have been generated and these artificially data have been used for validating of rock typing methods. To form more realistic pore networks, both regular and irregular pore network have been modeled and analyzed. Pore size... 

Drilling operation is one of the most important parts of oil production procedure. Therefore, drilling optimization has an effective role in ultimate benefits and total cost reduction. Also formation damage can affect reservoir performance. In this study, a combination of optimization methods for each part of drilling operation has been used and fitness function of total cost is presented. This function includes number of bit runs, bit selection, controllable parameters and drilling mud properties. For prediction of formation damage radius and variable risk analysis, two new methods are proposed and have been used as fitness functions. Finally, by suggesting a multi objective optimization... 

Since the beginning of industrial age the concentration of the greenhouse gases in the atmosphere has increased significantly. This is due to using fossil fuels (oil, gas and coal) exceedingly, leading to higher average temperature of earth and many environmental problems. The critical solution of controlling greenhouse gas emission is replacing other energy resources (for example; solar energy, wind energy and nuclear energy), while considering energy infrastructures shows this is a far solution. An early way for decreasing emission of greenhouse gases in atmosphere is injection of CO2 in geological formations. Moreover, in reservoir and environmental engineering, CO2 injection has been... 

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...