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Gravity drainage is the control mechanism of oil production from fracture reservoirs. The transfer of oil from the upper blocks to the lower blocks occurs through a capillary continuity mechanism or reinfiltration. One of the conditions for capillary continuity, which plays an important role in increasing oil recovery, is the formation of a liquid bridge in the fractures between the blocks. Therefore, quantitative analysis of the critical fracture aperture for the formation and stability of liquid bridges and the formation, growth and stability of flowing liquid droplets from the top block surface are still challenging and important topic in the study of fracture reservoirs. In this study,... 

The available investigations show that gravity drainage mechanism in fractured reservoir make a high recovery factor in comparison with other mechanisms. In recent years, the forced gravity drainage assisted by gas injection is also introduced; despite of its importance there is no comprehensive modeling study in the literature. The fractured reservoir is simulated frequently by dual porosity models in which the transfer function is the key issue for this method of simulation. This study makes an effort by comparison of different transfer functions with fine grid simulation results of a single block model, in order to evaluate their ability for simulation of forced gravity drainage... 

Gravity drainage is known as one of the major mechanisms of oil recovery in naturally fractured reservoirs which petroleum engineers conducted research in this realm. Block to block interaction such as capillary continuity and reinfiltration mainly control the efficiency of this mechanism. In this study, first of all, free fall and forced gravity drainage experiments have been conducted in a single block apparatus and effect of some parameters like, density viscosity relation, matrix permeability, vertical fracture aperture, presence of viscose force and type of injected gas were investigated, in the second step, three stack block apparatus were designed and constructed. This apparatus were... 

Liquid flow between two porous blocks in fractured reservoirs can occur through capillary continuity or re-imbibition. Studies have shown that capillary continuity via liquid bridges formed in horizontal fracture increases oil recovery from reservoirs. The critical fracture apertures for stability of liquid bridges, shape of curvature and fracture capillary pressure for prediction of fractured reservoir performance remain as controversial topics. Experimental results have shown that critical fracture aperture is a function of surface wettability and critical Bond number. Capillary pressure of fracture might be a positive or negative value caused by liquid bridges. The best method for... 

Fractured reservoirs constitute a major portion of world’s petroleum reservoirs. Gravity drainage is the controlling production mechanism in these reservoirs. Thus, investigation of performance and oil production in fractured models has been the subject of many researches. Despite the considerable number of experimental and modeling studies in this area, the method of scale-up in single or multi block models is not broadly investigated. This work is divided into two experimental and modeling sections. For the experimental study, free fall gravity drainage experiments in synthetic single or multi block porous media were performed in order to investigate effects of different parameters... 

Steam-Assisted Gravity Drainage (SAGD) is one of the best and the most effective methods of enhanced oil recovery (EOR) which is used in the production from Heavy Oil Reservoirs which constitute large amount of oil throughout the globe. In a typical process of SAGD, steam is injected into a horizontal well and the oil is produced several meters deeper in the ground. In order to increase the Recovery of this process, it is better to review on the Pre-heating methods around the injecting and producing wells. Pre-heating is important when the viscosity of the oil is large enough to prevent oil from any motion at the beginning of the SADG operation, and makes it necessary to to use a Pre-heating... 

Gravity drainage is known as the main mechanism for Enhanced Oil Recovery (EOR) in naturally fractured reservoirs. In fact, this mechanism is active in gas invaded zone. In spite of numerous researches in the area, the literature suffers from the lack of a comprehensive model for controlled gravity drainage. Calculating the accurate oil recovery and ultimate recovery factor is inevitable for a successful field development plan as well as enhancing oil recovery. To obtain the accurate values of the aforementioned parameters, an accurate model to solve nonlinear differential equations is necessary. To this end, COMSOL, the well known commercial CFD software, has been used for the modeling of... 

In this study, a tree-dimensional random pore-scale network model is used to simulate the membrane contactor porous medium. Drainage and imbibition phenomena is simulated to have a better knowledge of liquid and/gas intrusion trough the membrane porous structure. A genetic algorithm is used as an optimization tool. Several variables such as the number, radius and location of pores, the coordination number, as well as the radius and length of the throats are used herein as the optimization parameters. The difference between the binary SEM images and virtual sections on the generated network in conjunction with the permeability and mean pore size data were selected as the objective function.... 

The production of oil is challenging in the fractured reservoirs due to the large transmissibility contrast between matrix and fracture, and primary recovery is often low. The recovery efficiency depends on the relationship between the fracture and matrix permeability, and is strongly dependent on the wettability of the matrix, which reflects the imbibition potential of the reservoir. Among these parameters the multiphase fluid flow in gas invaded zone is the point of interest in this project. Gas injection in naturally fractured reservoirs maintains the reservoir pressure, and increases oil recovery primarily by gravity drainage and to a lesser extent by mass transfer between the flowing... 

In this work a generalized non-equilibrium model of three-phase flow in porous media including gravity as well as capillary terms is developed and used for analysis of Riemann’s problem in several three-phase systems. The proposed model uses the extension of Barenblatt model to three-phase systems considering dynamic effects in both relative permeability and capillary pressure functions. We compare the solution of the Riemann’s problem when non-equilibrium effects are included. While equilibrium formulation develops unstable oscillatory solution in the elliptic region, non-equilibrium solution is smooth and stable. The proposed non-equilibrium model is validated by the experimental data of... 

Most available methods which are well able to improve or dewater coarse soils have little success dealing with fine soils and clays and using these methods to dewater clays needs great amount of time and money. Electrokinetic Geosynthetic is one of new methods that have had a promising future. Regarding the importance and tremendous usage of dewatering in fine soils, the efficiency of electrokinetic geosynthetic method in dewatering fine soils has been taken under the consideration in this research. Following laboratory experimentation, numerical modeling of this process has been done. In this research some laboratory test has been done on kaolinite clay and the effects of pH of specimen,... 

Gravity Drainage and Capillary Imbibition are among the most important mechanisms in oil production from carbonate fractured reservoirs. In order to investigate the feasibility and effects of these mechanisms in oil recovery from carbonate cores, some different experiments were carried out at Sharif University Laboratories. Carbonate cores were taken away from the well-known Asmari outcrop, Asmari Mountain in south east of M.I.S. city and used in these experiments. Oil and gas samples were collected from field separators and recombined to reservoir composition. The Gas-Oil ratio was adjusted to obtain the reservoir fluid properties. A core flooding apparatus with various capabilities was... 

It is widely recognized today that excess moisture in pavement layers, when combined with heavy truck traffic and moisture-susceptible materials, can reduce the service life. Temperatures below freezing can also contribute to durability problems of saturated materials. A major objective in pavement design is to keep the base, subbase, subgrade, and other susceptible paving materials from becoming saturated or even being exposed to constant high moisture levels over time. The use of subsurface drainage has gained popularity over the past two decades, and many pavement agencies now routinely specify drainable pavement structures to reduce moisture-related problems in avements. In this... 

Gravity drainage is the self-propulsion of oil downward in the reservoir rock. Under favorable natural and operational conditions, it has been found to effect recoveries comparable to water displacement. With modern technical knowledge, the operator can often make a choice between dissolved gas drive, water drive and gravity drainage as the principal recovery agent in a reservoir. So far, gravity drainage has received less consideration than the other two. Gravity drainage is one of the most important processes taking place in fractured reservoirs and it plays a major role in oil recovery from low permeability matrix blocks during gas injection process. Gravity drainage is responsible for... 

This work describes the use of a two-dimensional numerical simulator for Steam Assisted Gravity Drainage (SAGD) using the model proposed by Coats et al with some improvements. Despite the Coats model this developed model accounts for capillary and gravity effects in the energy equation with a variable thermal conductivity of the formation. First, a sensitivity analysis is performed for SAGD process. Then, the simulator is used to describe the pre-heating process preceding SAGD. We studied two methods of preheating process and found that there exists an optimum method of preheating for any reservoir. We concluded that longer preheating period does not necessarily yield a faster recovery  

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... 

In this project some samples from the water which enters the plant and the effluent water were analyzed and the results were compared due to investigating the quality of water in Sangan mine tailing dams. Considering that Northern C mass contains more than two percent sulfur, it can produce AMD. Acid Mine Drainage (AMD), which is caused by the oxidation of sulfide ores in the mines, is the most important environmental problem. Anticipating potential problems of this waste can prevent the problem. To predict it, Acid-Base Accounting (ABA) test was used. The experiment's parameters like Maximum Potential Acidity (MPA) and Neutralization Potential (NP) were measured for more than 130 samples... 

Most of oil content, especially in Iran, has been reserved in fractured reservoirs, so study and modeling of production mechanism of these reservoirs are great of importance. Gravity drainage is one of these effective production mechanisms in fractured porous media which dynamic pore scale modeling of this mechanism will lead to better understanding of it. In this work, the effects of variety of parameters such as oil gravity, interfacial tension between oil and gas, pore and throat size distribution, fracture aperture, and block to block interaction (capillary continuity and reinfiltartion) have been investigated. So developed simulator in this work has two main and separated parts, which... 

Gas-oil displacement, when stabilized by gravity forces leads to high displacement efficiency, as manifested in high recovery factor associated with gas-cap drive and gravity drainage. The main objective of this research is improved understanding of drainage behavior and changes in flow properties when the importance of viscous, gravity and capillary forces varies. The influence of interplaying between controlling forces on relative permeabilities is also studied. Another objective of this work is to study effect of wettability on recovery under forced gravity drainage. To study drainage behavior under various dominant driving/resistive forces, a number of forced gravity drainage experiments...