numerical simulation

In many cases some barriers like low permeability, secondary porosity and decreasing in formation permeability due to damages casued by drilling, asphaltene and other problems confine oil production rate in unacceptable region and These problems reduce percentage of oil recovery from these reservoirs, These problems can be solved by utilizing hydraulic fracture method. A new model based on cohesive zone method coupling stress-seepage damage filed is developed to simulate the interaction between hydraulic fracture and natural fracture with using ABAQUS software. The effect of differential stress and approaching angle on the intersection between hydraulic fracture and natural fracture, as well as the effect of natural fracture cementing strength on the geometry of  hydraulic fracture propagation, have been investigated. While the hydraulic fracture initiates, propagates, and intersects with the natural fracture, it can either deflect into it or cross it by severing the natural fracture. The greater the approaching angle and differential stress , the easier it is for the hydraulic fracture to cross the natural fracture.The behavior of hydraulic fracture changes from deflection to crossing as the natural fracture cementing strength is increased.

The energy crisis and environmental concerns in recent decades are a serious challenge to human life. The fuel cell, especially the solid oxide type, has been welcomed due to its features such as fuel flexibility, good efficiency and no need for precious metals. However, the problems of hydrogen fuel, such as the low energy density of the gas phase, difficult storage and portability, have suggested ammonia as a suitable alternative fuel. In this research, tubular all porous solid oxide fuel cell ammonia fueled has been simulated and investigated. Therefore, the equations of conservation of mass, momentum, energy, species and electric flux are defined, coupled and solved in the form of finite element code. The results show that the presence of electrolyte porosity increases the efficiency of fuel cell ammonia fueled. It was also observed that the power and current density of the fuel cell have a direct relation with the operation temperature and flow rate and an inverse relation with the porosity of the electrodes.

This study addresses the numerical simulation of cohesive crack propagation and the problem of normal contact in porous media. Penalty method is used to inforce essential boundary conditions. The strong discontinuity in the deformation field is effectively modeled by exploiting the partition of unity property of element-free Galerkin shape functions and employing an external enrichment strategy. To account for the crack initiation and propagation behavior in mode I, which occurs under tensile stresses, as well as the compressive behavior at the edges of a closed crack in compression, the cohesive crack theory and the penalty method are incorporated into the existing computer program prepared for the simulation of porous media using the enriched element-free Galerkin method. The resulting algebraic system of equations are strongly non-linear. So, a suitable approach must be utilized to linearize and solve the equations. Newton-Raphson technique is utilized in this study for this purpose. The results obtained from solving the problems of tensile cracks and cracks under compression (i.e., the contact of two crack edges) indicate the capabilities of the numerical formulation and the prepared computer program. Expanding the prepared numerical model allows for the modeling of crack growth problems in porous media in the presence of fluids, as seen in processes like hydraulic fracturing.

Formation damage in hydrocarbon reservoirs around the wellbore is inevitable, and it can happen from the earliest stages of drilling to the latest hydrocarbon recovery stages by tertiary enhanced recovery methods. Numerical simulations of production behavior around wellbore perforation in single-phase and two-phase states have been conducted by the CFD method to investigate the effect of perforation geometry on formation damage. Moreover, formation damage due to drilling mud penetration into the perforations by dispersion mechanism has also been analyzed. The results of the simulation were validated in good accordance with the published data. Based on simulation results, although perforations enhance the drilling mud penetration damage, especially for perforation lengths up to 20 cm, they can effectively reduce perforation skin if they become adequately cleaned. Perforation density, length, and diameter have the most pronounced effect on reducing the skin factor. There is almost a linear relationship between skin factor and clean perforation diameter. Since larger diameters come with shorter lengths, perforation optimization is required according to casing material, hole size, rock mineral, and perforation technology available.

Accurate measurement of gas flow is a basic need in domestic use. Diaphragm gas meters are currently used to measure domestic gas consumption, which is a very old and inaccurate technology. In recent years, the use of thermal MEMS flowmeters has been growing due to their small size, low power consumption, and good accuracy, but their limited measurement range has prevented them from being used to measure domestic gas consumption. In order to eliminate this limitation, in the present study, a bypass system similar to capillary tube flowmeters was introduced, which it has also been used in several commercial microthermal flowmeters. This system must be designed in such a way that an acceptable flow enters the bypass (microchannel). Therefore, in this study, for the first time, the effect of different geometrical parameters on the flow rate to the bypass in the flow range of domestic consumption was studied by simultaneously solving turbulent and laminar flow equations through fluid dynamics simulation. According to the results, with the higher the height of the bypass channel is, the smaller the diameter of the laminar flow element is and the less bypass-laminar flow element distance is, more gas enters the bypass. Finally, the channel height of 160 micrometers, the distance of 2 mm between bypass entrance and laminar flow element, and the square arrangement of the laminar flow element with a diameter of 1.8 mm can be appropriate. In these specifications, 100 to 220 percent more flow enters the bypass than most other configurations of the work.

Optimal reservoir management, modeling and production, depend on understanding the connectivity between production wells in an oil reservoir. Using numerical simulation and a reservoir permeability map can clear this feature, however, it is a time-consuming method and the presence of uncertainty in the input data of simulators leads to employ other methods to understand the feature. Having new sensors that are permanently placed in the wellbore, large amounts of production data (production rate and bottom hole pressure) are available. In recent years, intelligent data-driven techniques have been used to work with the large amount of data obtained from production wells. This paper uses a data-driven approach based on detecting important production well events during its production life. Important well events are divided into three categories: (1) increasing, (2) decreasing, and (3) no flow (shut in the well by operator). These events are identified using derivative and slope of the production figures and some limiting factors. Afterwards, the algorithm has to find the related events between the production wells, and based on the importance of the events, the inter-well connectivity among production wells is determined which it is shown as a connectivity map. A synthetic reservoir was first developed in the Eclipse simulation software, and the three high-permeability streaks were considered between three well pairs. Next, its production data were used as the data-driven model’s input, which it is programmed in MATLAB software, in order to identify the three high-permeability streaks via the data-driven model.

A two-dimensional hydrodynamic simulation of two-phase flow in a rotating drum under rolling conditions was examined in this study. The Eulerian-Eulerian multi-phase approach was utilized in this study to model the gas-solid system in a rotating drum, combined with the kinetic theory of granular flow. The results of these simulation was verified with experimental data was reported with Santos et al. (2015) which indicates that the results are consistent with experimental work. In this study impact of restitution coefficient on active layer thickness was investigated. For this purpose the restitution value set to different values (0.85, 0.9, 0.92, and 0.95) and their effect on the thickness of active layer on the rotating drum was examined. The thickness of the active layer was increased by raising the coefficient of restitution from 0.85 to 0.95, which, given that the majority of mixing occurs in rotating beds, can demonstrate an improvement in the degree of mixing in rotating beds with the results.

The purpose of this study is to investigate the flow behavior of two-phase gas flow in a Seal pot of a Flare Network. Seal pots is one of the most important equipment in the Flare network, which is responsible for stacking gas flares. The inadequate functioning of this equipment will result in fluctuations in outlet pressure, environmental pollution, and increased probability of explosion in the network. In order to solve the problem, a new geometry was proposed by applying changes to the geometry of the existing liquid abandoned reservoir. Both designs were modeled and simulated using Ansys Fluent software with a fluid volume multi-phase model. The simulation results showed that under the same conditions, the older design in the lower reaches dose not function property and has operational malfunction. This defect is less common in the newer model, which can be corrected by applying minor changes to the corresponding buffer.

In this study, effect of a parameter has been investigated with FLUENT simulator software on increasing sulfur recovery and reaction furnace temperature of Abadan Oil refinery. Results like reaction furnace temperature and mole fraction of products have been validated with experimental data. Effect of O2 enrichment on reaction furnace temperature and amount of sulfur recovery has been studied with mentioned software. In the condition that O2 concentration increases, combustion temperature increases uniformly and results show that sulfur recovery reached to its maximum in high concentration of O2. Modeling turbulent flow, k-e model and for modeling combustion, eddy dissipation model have been used.

The morphological attributes of polymer blends have a significant influence on the final properties of the blend. Many attempts have been made to simulate morphological changes of a blend in various equipments, using several mathematical models and numerical simulations. In this study, mixing of non-Newtonian fluids was simulated using a power-law rheological model in a typical twin screw extruder in three dimensions. Modified marker and cell (MAC) method was used for simulation. In modified MAC, for simulation of polymeric fluids flow, power law rheological model was used to generalize velocity equations to non-Newtonian fluids. Interfacial tension and viscosity ratios were used to introduce the effect of miscibility parameter. In this method, momentum equations were solved and discredited using finite volume method. The linear algebraic equations were solved using three diagonal matrix and the coefficients of network’s points were obtained. Then, velocity values were obtained for any control volume in three dimensions by introducing typical rheological and interfacial tension parameters for a pair of polymers. The under relaxation factors (URFs) were used for velocities in three dimensions and pressure for faster convergence. Then, new spatial peculiarities of particles of two phases were traced by taking appropriate time intervals. The geometry of screws in twin screw extruder was achieved using hypothesis of imaginary domain of screws tips. A twin screw extruder with glass barrel was designed and constructed for intuitive investigation of mixing development. Mixing of polymer pairs of different miscibility was performed in equal time intervals. The experimental pictures were compared with the simulation results. A very good agreement was observed between the results of numerical simulation and experimental images in both miscible and immiscible fluids. The determined separation areas for theoretical and experimental images also confirmed the accuracy of the simulation. Therefore, modified marker and cell (MAC) method could be used to simulate the mixing of polymer blends in twin screw extruder, as the most common blending equipment.

Measurement of temporal-spatial distribution of surface subsidence as a result of production from hydrocarbon reservoirs is a relatively common practice worldwide; however, it is set aside in Iran, although it seems that prediction of subsidence trend at the beginning of the reservoir life can be beneficial in future production estimates. In this paper, the accuracy of the numerical modeling for calculating subsidence process is evaluated by comparison with the in-situ measurements recordings, as well as those designated from analytical solutions for two hydrocarbon reservoirs in the USA, and the Netherlands. It was observed that the numerical simulations can well trace the subsidence trend in spite of elastic behavior assumption, and other simplifications considered. Although, the real mechanism of subsidence is inelastic, and parameters variations are possible. Afterwards, the distribution of temporal-spatial surface subsidence in a specified zone of Kupal oil field, Iran, was predicted. Moreover, unlike the verification examples, in which pressure changes in the whole reservoir had been considered to determine settlements, the “production history” of some wells was used in the simulations. It was concluded that production from the selected area in the Kupal oil field has resulted in surface subsidence in the range of 26 to 32 cm in the period between years of 1372-1396.