Sharif Digital Repository

In the oil and gas industry, in different stages of exploration and production of oil from hydrocarbon reservoirs, there are several challenges, most of which are due to unbalanced physical-mechanical conditions of the formations. Today, geomechanics of reservoirs is recognized as a key to analyze and solve such problems.Activities such as drilling, perforation, fracturing, production and fluid injection into the reservoir can alter the reservoir stress field and can cause rock deformation. Excessive compaction of reservoir rock can cause surface or seabed subsidence and damage to surface facilities and subsurface tubular. In general, rock compaction can cause many problems if not predicted... 

Considering that hydrocarbon production, reduces energy of reservoir and causes part of the valuable compounds remaining in the oil or gas reservoir and can not be extracted by reservoir energy, so optimization of production by control flow rate, drilling new wells and applying lOR and EOR methods in order to increase hydrocarbon recovery is necessary. Gas and water inject through injection well into the reservoir for improve oil recovery. As implementation of different production and injection scenario is very expensive. Simulation of different method and applying the best is very helpful and necessary. In this study we use Eclipse software that is one of the best software that can simulate... 

Digital analysis of reservoir rocks prepares a powerful tool in the field of porous media studies and provides appropriate information of single / multiphase flows by performing numerical simulations on porous media images. In order to access the necessary tools to benefit from digital rock analysis and characterization, we need accessing the porous media images, the geometric distribution and the spatial distribution of pores and grains through imaging or reconstruction methods. Porous media reconstruction methods are known as an alternative to imaging techniques. In addition, reconstruction methods have the ability to fix problems and imperfections associated with imaging, such as... 

It is common to inject gas in naturally fractured reservoirs to maintain the reservoir pressure. Recovery will be the result of the complex interplay of several mechanisms such as viscous flow, extraction by molecular diffusion, gravity drainage, oil swelling and capillary force. Generally the main mechanism is gravity drainage However in many cases like low permeability of matrix, small matrix block size and high capillary pressure; gravity drainage may be very low or ineffective. Low permeability results inefficient viscous displacement too. Therefore in these cases the main mechanism is diffusion. The parameters influences the diffusion are: The nature of the injected gas, the composition... 

Heavy oil reservoirs include a major part of the world’s oil reservoirs. Therefore consideration to their enhanced oil recovery (EOR) aspects has a great importance. In heavy oil reservoirs secondary and tertiary EOR methods, have an insignificant effect on oil recovery and so we’d better to use chemical methods to improve mobility and oil recovery. One of the appropriate EOR methods which has attracted a lot of attention is alkaline – surfactant – polymer (ASP) flooding which has a considerable impact on EOR from heavy oil reservoirs. In this EOR method, the low concentration of surfactant in the injecting fluid, results in a low or ultra-low interfacial tension (IFT) between residual oil... 

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... 

During the production of crude oil from reservoirs, the production of quantities of formation water along with this oil, causes the crude oil does not have the necessary indicators for transportation, refining and ultimately export. The presence of water and salt along with crude oil causes corrosion of refinery and transmission equipment and makes oil unfavorable in terms of economic efficiency (both for domestic use and for export). water and salt produce stable emulsion with oil that can be stable for a long time and can not be easily separated from crude oil. Therefore, separation of water and salt from crude oil is one of the most important issues in the oil industry. Breaking this... 

Free fall gravity drainage is one of the most effective mechanisms of producing the oil from the matrix blocks in the gas invaded zone of the naturally fractured reservoirs. Although several analytical models have been proposed to characterize this mechanism in a matrix block, but these models suffer from the practical or theoretical viewpoints. In this study, a new analytical model was presented to predict the oil production rate versus time from a homogeneous matrix block under free fall gravity drainage mechanism. The model was developed by considering the balance between involved forces in the gas-oil gravity drainage process. By simplifying the equation derived from the momentum... 

One of the main parameters in modeling of two phase gas and oil flow is an accurate relative permeability functions. This importance will be more intensified when the miscibility condition approaches. In miscible condition due to reduction of interfacial tension between oil and gas phases, parameters of conventional relative permeability functions will change and this changing affects on production results such as oil and gas recovery and also pressure drop along the core. All of the previous studies could not present a unique and consistent model to show the effect of near miscibility condition on relative permeability curves. In this work, these changing of parameters will be investigated... 

With the decline in oil discoveries during the last decades, it is believed that enhanced oil recovery (EOR) technologies will play a key role to meet the energy demand in coming years. Polymer flooding has been commonly used worldwide as one of the EOR processes. Literature reviews show that the active water-soluble polymers have a number of limitations related to their surface absorption, undesirable plugging, polymer concentration limitation,expensive, and low thermal, mechanical, bacterial, and salt tolerance. Up to now, five different polymer categories (i.e. polyacrylamide, hydrolyzed polyacrylamide, acrylamidebased resistant copolymers, associative copolymers, and thermoassociative... 

Interfacial Tension (IFT) as a main parameter for gas flooding efficiency in oil reservoirs depends highly on pressure, temperature, and composition of the reservoir fluids. Therefore, it is important to measure this parameter at real reservoir condition for successful field development plan. In this study, an axisymmetric drop shape analysis (ADSA) has been utilized to measure the equilibrium IFTs in crude oil-CO2 as well as crude oil-N2 systems at different temperatures and pressures. Moreover, minimum miscibility pressures (MMP) and first-contact miscibility pressures (Pmax) of crude oil/CO2 and crude oil/N2 systems at different temperature levels are determined by applying vanishing... 

Majority of the oil and gas reservoirs, in the main hydrocarbon production regions around the world, are naturally fractured reservoirs. Fractures play an important role in reservoir fluid flow either in the form of high permeable complex conduits or strong permeability anisotropies. Realistic characterization of naturally fractured reservoirs requires an exhaustive understanding of fracture connectivity and fracture pattern geometry. These subsequently demand description of many fracture parameters such as density (intensity), spacing, orientation, size and aperture. Therefore, a first step in fractured reservoirs characterization is the static geometric modeling of the subsurface fracture... 

Polymer flooding is a famous enhanced oil recovery method and is used to reduce mobility ratio of displacing fluid to displaced fluid by forming a stable front in displacing process. Due to high costs, polymer flooding faces economical risks and from this point of view, performance investigation of polymer flooding in laboratory scale was concerned. In this project, performance of 7 types of polymers which have different rheological properties were investigated in fractured/non-fractured carbonated and sandstone reservoirs. These polymers consists of 4 commercial polymers, one branched polymer, one synthetic polymer and one polymer composite which have different molecular weight,... 

In the upstream asphaltene flow assurance community, both academics and industries are actively involved to predict the asphaltene deposit profile in wellbores and pipelines. The main objective of this study is to contribute to the thermodynamic and transport modeling of asphaltene in order to predict its precipitation, aggregation and deposition. For a better knowledge of the flow properties of asphaltene containing crude oils, it is necessary to understand how asphaltene affect the rheological properties. In this work, the information on such rheological properties of oil-asphaltene slurry systems is provided. The results of rheological experiments for two Iranian crude oils show that the... 

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 addition, during the early stage of life of a reservoir, due to the lake of certain data, this method is usually based on analogues or rules of thumb and not detailed reservoir modelling. Therefore, there is a great incentive to produce much simpler physically-based methodologies. The main focus of this thesis is to use percolation approach to estimate the uncertainty in the reservoir properties. This method considers a hypothesis that the reservoir can be split into either permeable (i.e....