Sharif Digital Repository

The coning phenomenon usually occurs in water and gas cap drive reservoirs. Water coning in Iranian hydrocarbon reservoirs is one of the most important problems that affects the cumulative production, operation costs and causes environmental problems. Before producing from a reservoir, its fluids are in equilibrium and their contact surfaces remain unchanged, but after starting production from the reservoir, when the viscous force overcome gravitational force in vertical direction, contact surfaces will displace and coning will occur. So, the production rates will be controlled in a range that prevents entering water and gas to the production well. For this reason, investigation and modeling... 

The coning phenomenon usually occurs in water and gas cap drive reservoirs. Water coning in Iranian hydrocarbon reservoirs is one of the most important problems that affects the cumulative production, operation costs and causes environmental problems. Before producing from a reservoir, its fluids are in equilibrium and their contact surfaces remain unchanged, but after starting production from the reservoir, when the viscous force overcome gravitational force in vertical direction, contact surfaces will displace and coning will occur. So, the production rates will be controlled in a range that prevents entering water and gas to the production well. For this reason, investigation and modeling... 

Movement and transportation of fine particles in formations leads to clogging the pores and reduction in permeability. This type of formation damage is stronglycontingent upon water salinity and ionic conditions in the formation. The main parameters which control the particle release are the interactions and forces between particles and porous medium surfaces. Changing salinity which leads to pH alteration, affects these interactions and subsequently the fine migration process. Hence, pH and salinity variations should be considered to study and evaluate the portion of fine migration in formation damage. The principal challenge in this research therefore, is to try to change the surface... 

Recently, there has been renewed interest in semantic word representation also called word embedding, in a wide variety of natural language processing tasks requiring sophisticated semantic and syntactic information. The quality of word embedding methods is usually evaluated based on English language benchmarks. Nevertheless, only a few studies analyze word embedding for low resource languages such as Persian. In this paper, we perform such an extensive word embedding evaluation in Persian language based on a set of lexical semantics tasks named analogy, concept categorization, and word semantic relatedness. For these evaluation tasks, we provide three benchmark data sets to show the... 

The knowledge of the conductivity across the reservoir that is based on the swept fraction controls the recoverable rates of the hydrocarbon in the secondary displacement processes. Most of the time, we need a fast estimation of the conductivity for decision making during field development. Percolation theory is a very useful tool to get this goal. According to this fact that the results of this method are universal, they could be used widely. In this study connectivity and conductivity percolation models are developed and the universal exponents for connectivity and conductivity in fractured reservoir as well as their dependency on the correlation length are investigated. For L< ξ the... 

In recent years, growing interest in underbalanced drilling has resulted in the rapid development of its associated equipment technology, practices, and procedures. Underbalanced drilling is used to avoid lost circulation, formation damage, and decreasing weight on bit. However, the risk of wellbore collapse due to lake of hydrostatic mud pressure is high; therefore, using good geo-mechanical model may avoid wellbore instability problems. In order to evaluate the potential for wellbore instability, it is necessary to use an elastoplastic model to compute the stresses and strains around the bore hole. Furthermore, it should be mentioned that the laser drilling process depends extremely on the... 

Simultaneous water and CO2 injection has been performed on a sandstone core to evaluate oil recovery under the secondary and tertiary near-miscible injection modes. It is demonstrated that secondary SWACO2 injection as well as tertiary flood is an effective method for the oil/residual oil recovery from oil saturated/water-flooded porous media. In the secondary SWACO2 injection, the ultimate oil recovery increases by increasing SWAG ratio from 0.2 to 0.4 but due to some limits, e.g. topological effects, prohibiting contacting of injected gas with residual oil in pores, altering SWAG ratio from 0.4 to 0.6 showed no effect on ultimate oil recovery. Secondary SWACO2 injection can recover higher... 

As many fields around the world are reaching maturity, the need to develop new tools that allows reservoir engineering to optimize reservoir performance is becoming more demanding. One of the more challenging and influential problems along these lines is the well placement optimization problem. Determining of the location of new wells is a complex problem that depends on reservoir and fluid properties, well and surface equipment specifications, and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the simulator as the evaluation function, although accurate, is in most cases infeasible due to the number of simulations required.... 

A new and general procedure for history matching that uses streamline simulation and a gradual deformation technique has been proposed. Streamline trajectories define the major flow paths and help the algorithm to modify the reservoir model only in the regions that cause the mismatch between simulation results and field observations. The use of a gradual deformation technique enables the algorithm to remain constrained to reservoir geostatistics. It also reduces the number of independent variables in the optimization problem. In our algorithm, effective conductivities are defined along each streamline. The effective streamline conductivities are then adjusted using the values of measured and... 

The knowledge of the conductivity across the reservoir that is based on the swept fraction controls the recoverable rates of the hydrocarbon in the secondary displacement processes. Most of the time, we need a fast estimation of the conductivity for decision making during field development. Percolation theory is a very useful tool to get this goal. According to this fact that the results of this method are universal, they could be used widely. In this study connectivity and conductivity percolation models are developed and the universal exponents for connectivity and conductivity in fractured reservoir as well as their dependency on the correlation length are investigated. For L< ξ the... 

It is not common to build a geomechanical model for depleted reservoirs as logging and coring are costly and time consuming in such reservoirs. On the other hand, in regular analysis of wellbore stability, the effect of time is completely ignored. As a result, with time there will be some errors in the evaluation of wellbore stability in depleted reservoirs. In order to determine the optimum wellbore trajectory during the reservoir life, it is necessary to have a model which can estimate the rock properties based on the first full logging suite and also consider the depletion effect. In this study, a novel model is proposed which combines a mechanical earth model, borehole circumferential... 

In this paper we present new methods to estimate the effective permeability (keff) of heterogeneous porous media with a wide distribution of permeabilities and various underlying structures, using percolation concepts. We first set a threshold permeability (kth) on the permeability density function and use standard algorithms from percolation theory to check whether the high permeable grid blocks (i.e., those with permeability higher than kth) with occupied fraction of “p” first forms a cluster connecting two opposite sides of the system in the direction of the flow (high permeability flow pathway). Then we estimate the effective permeability of the heterogeneous porous media in different... 

Most investigations showed that the prevalent thermodynamic models are incapable of predicting asphaltene precipitation without extensive data fitting. This is primarily due to lack of knowledge of the asphaltene properties, its complex nature and the large number of parameters affecting precipitation. Hece, several authors tried to generate a simple and universe mathematical model in order to predict the amount of asphaltene precipitation. In spite of these efforts, the authors only considered temperature and type of solvents as the effective parameters in generating their scaling equations. The major disadvantage of these models is their inability in predicting the amount of asphaltene... 

In this paper, new arrangements of triangular winglet as a turbulator are numerically studied through a cylindrical tube. Triangular winglets are commonly placed on one side of a rectangular plate and inserted inside the tube. However, in present work, the winglets are located on both sides of the rectangular plate to further enhance the thermal performance of the fluid flow through the tube. Both backward and forward configurations of the winglets are analysed. Moreover, despite the importance of “latitudinal pitch of the winglets” and “winglet-plate angle” no investigation has been evaluated these parameters which will be evaluated in this work. Moreover, as no exergetic evaluation has... 

A novel technique for upscaling of detailed geological reservoir descriptions is presented. The technique aims at reducing both numerical dispersion and homogenization error, generated due to incorporating a coarse computational grid and assigning effective permeability to coarse grid blocks respectively. In particular we consider implicit-pressure explicit-saturation (IMPES) scheme where homogenization error impacts the accuracy of the coarse grid solution of the pressure equation. To reduce the homogenization error, we employ the new vorticity-based gridding that generates a non-uniform coarse grid with high resolution at high vorticity zones. In addition, to control numerical dispersion,... 

Investigating the impact of geological uncertainty (i.e., spatial distribution of fractures) on reservoir performance may aid management decisions. The conventional approach to address this is to build a number of possible reservoir models, upscale them, and then run flow simulations. The problem with this approach is that it is computationally very expensive. In this study, we use another approach based on the permeability contrasts that control the flow, called percolation approach. This assumes that the permeability disorder of a rock can be simplified to either permeable or impermeable. The advantage is that by using some universal laws from percolation theory, the effect of the complex... 

This paper proposes a novel 3D action recognition technique that uses time-series information extracted from depth image sequences for use in systems of human daily activity monitoring. To this end, each action is represented as a multi-dimensional time series, where each dimension represents the position variation of one skeleton joint over time. The time series is then mapped onto a vector space using Dynamic Time Warping (DTW) distance. Furthermore, to employ the correlation-distinctiveness relationship of the sequences in recognition, this vector space is remapped onto a discriminative space using the regularized Fisher method, where final decisions about the actions are made. Unlike... 

We introduce the notion of private set operations (PSO) as a symmetric-key primitive in the cloud scenario, where a client securely outsources his dataset to a cloud service provider and later privately issues queries in the form of common set operations. We define a syntax and security notion for PSO and propose a general construction that satisfies it. There are two main ingredients to our PSO scheme: an adjustable join (Adjoin) scheme (MIT-CSAIL-TR-2012-006 (2012) Cryptographic treatment of CryptDB's adjustable join. http://people.csail.mit.edu/nickolai/papers/popa-join-tr.pdf) and a tuple set (TSet) scheme (Cash, D., Jarecki, S., Jutla, C. S., Krawczyk, H., Rosu, M.-C., and Steiner, M.... 

Reliability is an essential factor in distribution networkt expansion planning. However, standard distribution reliability assessment techniques rely on quantifying the impact of a pre-specified set of events on service continuity through the simulation of component outages, one at a time. Due to such a simulation-based nature, the incorporation of reliability into distribution network expansion planning has customarily required the application of heuristic and metaheuristic approaches. Recently, alternative mixed-integer linear programming (MILP) models have been proposed for distribution network expansion planning considering reliability. Nonetheless, such models suffer from either low... 

One of the main concerns in source water protection and supply relates to the savings in water consumption in the building sectors. Office buildings are responsible for a considerable amount of water consumption worldwide. Thus, regulations on office buildings' water consumption would substantially reduce water consumption in the city as a whole. In order to achieve this objective, water indicators should be determined using an appropriate method. The present study focuses on the evaluation of water consumption patterns in an office building as well as the determination of the fundamental indicators for water conservation and optimization of water consumption patterns. To design and...