Simulation Of Gas Injection Research Articles

Exploring different FEM strategies for hydro-mechanical coupled gas injection simulation in clay materials

Over the last few decades, the study of gas injection in porous media, particularly under multi-field coupled conditions, has emerged as a prominent focus within the field of geotechnical engineering. This article presents a comprehensive comparison of three numerical strategies, evaluating their impact on computational efficiency and result accuracy during Hydro-Mechanical (HM) coupled simulations of gas injection in clay-based geomaterials. This comprehensive comparison encompasses three numerical simulation methods for the mechanical sub-problem: The Standard Finite Element Method (SFEM), the Standard Finite Element Method with Selective Integration (SFEM+SI), and the Mixed Finite Element Method (MFEM). The Heat and Gas Fracking model (HGFRAC) is introduced to illustrate the computational characteristics of these methods. The results indicate that the effective application of SFEM is heavily dependent on a high-precision mesh. Convergence issues may arise when dealing with relatively coarse meshes. Nevertheless, these convergence issues can be effectively mitigated by incorporating either the Selective Integration method or the MFEM formulations. In terms of computational efficiency, it is evident that the SFEM+SI method demonstrates higher efficiency than SFEM and MFEM. However, it is noteworthy that the computed gas flow patterns of SFEM and SFEM+SI can be affected by the alignment of the mesh. With MFEM, displacements and strains are calculated as independent unknowns, enhancing result accuracy and achieving mesh independence.

Optimized lower pressure limit for condensate underground gas storage using a dynamic pseudo-component model

In the context of gas injection in reservoirs, the dilution process of components' thermodynamic properties has not been adequately represented in traditional numerical simulation methods. This study focuses on the Dalaoba condensate underground gas storage (CUGS) in China and establishes a dynamic pseudo-component model to identify the equilibrium point for gas storage facility efficiency and the condensate oil recovery rate. Using a multi-objective particle swarm optimization approach, thermodynamic parameters are estimated as functions of the injected gas volume. This dynamic pseudo-component model is then utilized to find the optimized lower pressure limit for CUGS by assessing condensate oil production, gas flow capability, and water encroachment. Results show that the dynamic pseudo-component model can represent the process of thermodynamic property changes towards lighter components during natural gas injection. The case study demonstrates that conventional models overestimate condensate oil production, while the dynamic model achieves an accuracy rate of 92.8 % with historical data. The dynamic pseudo-component model offers valuable insights for large-scale gas injection simulation, promoting stable and efficient natural gas storage and supply in CUGS.

3D Simulations of gas injection on callovo-oxfordian claystone assuming spatial heterogeneity and anisotropy

A series of gas injection tests on Callovo-Oxfordian (COx) claystone from the Bure underground research laboratory (URL) in France were carried out at the British Geological Survey (BGS). The tests were performed using a triaxial apparatus specifically designed to capture small volumetric strains induced by the injected gas flow and consequent material dilatancy. The long-duration experiments were monitored throughout. Measurements also included pressure, stresses (axial and radial stresses prescribed for each test stage), rate of gas inflow, gas outflow volume as well as pore-pressures observed at various points of the sample. A coupled hydro-gas-mechanical 3D numerical model has been developed to simulate the tests. Initial permeability is assumed heterogeneous throughout the specimen and embedded fractures are incorporated in the formulation. Gas pressure-induced deformations during the test lead to variations of permeability due to changes in matrix porosity and, especially, fracture aperture as well as fracture orientation due to material anisotropy. A programme of sensitivity analyses involving the variation of different aspects and parameters of the model contributes to a better understanding of the phenomena and highlights its complexity. The model is able to reproduce the observed behaviour of the tests.

Numerical study of gas-injection induced pool sloshing behavior using MPS method

When a Core Disruptive Accident (CDA) occurs in a Sodium-cooled Fast Reactor (SFR), as the accident progresses, its core may form a pool of molten fuel. When the molten fuel pool expands, a certain amount of coolant may be entrained in it. Because of the Fuel-Coolant Interaction (FCI), the molten fuel pool will have centralized sloshing behavior, making the fuel distribution more dense, leading to the risk of re-criticality, therefore, the study of centralized sloshing behavior is of great significance for evaluating the impact of the CDA. Under various experimental conditions, the sloshing experiment of gas injection can effectively simulate the mechanism and characteristics of centralized sloshing behavior. In this study, numerical simulation of gas-injection induced sloshing behavior is performed based on the Moving Particle Semi-implicit (MPS) method. Simulation results are compared with the experimental results. The results show that the deformation of bubble shape and liquid level in the sloshing characteristics are in good agreement with the experimental results. Therefore, the numerical simulation method established in this study can be used to study the pool sloshing characteristics induced by gas injection.

Horizontal well spacing optimization and gas injection simulation for the ultra-low-permeability Yongjin reservoir

Optimal spacing for vertical wells can be effectively predicted with several published methods, but methods suitable for assessing the proper horizontal well spacing are rare. This work proposes a method for calculating the optimal horizontal well spacing for an ultra-low permeability reservoir – the Yongjin reservoir in the Juggar Basin, northwestern China. The result shows that a spacing of 640 m is the most economical for the development of the reservoir. To better develop the reservoir, simulation approaches are used and a new model is built based on the calculated well spacing. Since the reservoir has an ultra-low permeability, gas injection is regarded as the preferred enhanced oil recovery (EOR) method. Injection of different gases including carbon dioxide, methane, nitrogen and mixed gas are modelled. The results show that carbon dioxide injection is the most efficient and economical for the development of the reservoir. However, if the reservoir produces enough methane, reinjecting methane is even better than injecting carbon dioxide.

Simulation of gas injection from a long tube into a liquid-filled pipe

The data on the evolution of the interface at the sudden injection of gas from a long tube into a liquid column was obtained. High speed video of experiments and calculations in OpenFoam software package were used as research methods. Investigations were performed for different initial pressures. Typical configurations of the interface for different time periods were shown both experimentally and numerically.

Three-dimensional simulation of gas injection into an open fluid-filled pipe region

Three-dimensional simulation of air injection into a liquid (water, liquid lead) at large pressure drops in a three-dimensional formulation has been carried out. A significant difference in the formation of the air volume form at injection of water and liquid lead is shown. The instability of the interfacial surface in the form of annular waves and axial cavity on the upper surface of the slug has been revealed in three-dimensional calculation. For the three-dimensional case the gas-dynamic structure of the compression jumps and the Mach disk is found to be more pronounced for the supersonic underexpanded jet inside the slug.

Physical Simulation Behavior of the Slag in Gas Injection with Non-consumable Lance and Porous Plug for Secondary Refining Operations

In secondary refining operations, injection of inert gases into the metal bath is required to generate stirring in order to produce cleaner steels with low sulfur, ultra-low contents of nitrogen and hydrogen gases as well as improving both temperature and composition homogenization of the steel and control the inclusions and floating of them. To demonstrate the viability and competitiveness of the non-consumable lance versus porous plugs, a series of experiments in a model of secondary refining ladle were carried out in previous research (Liu et al. in ISIJ Int 57:1971, 2017). Simulation of gas injection was carried out to test the two methods: porous plug and non-consumable lance. It was found that the porous plug injection involves shorter mixing times (10–12 s) when it is positioned in an intermediate point between the center and edge of the ladle and with the increase in the airflow injected, as compared to the lance. However, one problem with this technique in the actual plant is the metal oxidation because the liquid metal is exposed to air as a result of excessive agitation. In this work, gas injection through porous plug and non-consumable lance into secondary refining ladle was simulated by the addition of oils of different densities, to simulate the behavior of the slag of different viscosities. The results show that the non-consumable lance exhibits less water surface area exposed compared with the porous plug. This means less metal is exposed to the environment and less oxidation of it, under the same agitation conditions.

Numerical Simulation of Gas Injection in Vertical Water Saturated Porous Media

We present numerical simulations of drainage induced by air injection in a vertical water-saturated Hele-Shaw cell filled with glass microbeads. We use the macroscale Subsurface Transport Over Multiple Phases (STOMP) simulator developed by the Pacific Northwest National Laboratory’s Hydrology Group. To trigger fingering, we use random permeability fields consistent to capillary entry pressure fields. We compare the numerical results to our own experimental results shown in a previous study. We analyze the effects of the microheterogeneity degree as well as the macroscopic parameters on the gas saturation results. The main objective of the work is to investigate how microscopic effects could be accounted for by macroscopic variables during drainage.

TOKES simulations to compare gas and pellet injection for disruption mitigation in ITER

Disruption mitigation by shattered Ne pellet injection (SPI) has been simulated for an H-mode ITER D-T discharge of 280 MJ stored energy using the 3D TOKES code. Heating of the first wall from the radiation flash during the thermal quench of the disruption initiated by the injected pellets has been assessed. The dynamics of Ne plasma expansion in the core with radiation from this plasma have been simulated for the series of pellet sizes from 5.4 × 1024 to 8.6 × 1022 Ne atoms. The threshold pellet size for irradiation of the core energy has been found. The results of SPI and massive gas injection simulations are compared.

Modeling of rapid shutdown in the DIII-D tokamak by core deposition of high-Z material

MHD modeling of encapsulated payload pellet injection (shell pellet injection) for disruption mitigation is carried out under the assumption of idealized delivery of the radiating payload to the core, neglecting the physics of shell ablation. The shell-pellet method is designed to produce an inside-out thermal quench in which core thermal heat is radiated while outer flux surfaces remain intact, protecting the divertor from large conducted heat loads. In the simulation, good outer surfaces remain until the thermal quench is nearly complete, and a high radiated energy fraction is achieved. When the outermost surfaces are destroyed, runaway electron test orbits indicate that the rate of runaway electron loss is very fast compared with prior massive gas injection simulations, which is attributed to the very different current profile evolution that occurs with central cooling.

Effects of outer top gas injection on ICRF coupling in ASDEX Upgrade: towards modelling of ITER gas injection

The influence of outer top gas injection on the scrape-off layer (SOL) density and ion cyclotron range of frequency (ICRF) coupling has been studied in ASDEX Upgrade (AUG) L-mode plasmas for the first time. The three-dimensional (3D) edge plasma fluid and neutral transport code EMC3-EIRENE is used to simulate the SOL plasma density, and the 3D wave code RAPLICASOL is used to compute the ICRF coupling resistance with the calculated density. Improvements have been made in the EMC3-EIRENE simulations by fitting transport parameters separately for each gas puffing case. It is found that the calculated local density profiles and coupling resistances are in good agreement with the experimental ones. The results indicate that the SOL density increase depends sensitively on the spreading of the injected outer top gas. If more gas enters into the main chamber through the paths near the top of vessel, the SOL density increase will be more toroidally uniform; if more gas chooses the paths closer to the mid-plane, then the SOL density increase will be more local and more significant. Among the various local gas puffing methods, the mid-plane gas valve close to the antenna is still the best option in terms of improving ICRF coupling. Differences between the outer top gas puffing in AUG and the outer top gas puffing in ITER are briefly summarized. Instructive suggestions for ITER and future plans for ITER gas injection simulations are discussed.

Физическое моделирование режимов газового воздействия на нефтегазоконденсатных месторождениях Восточной Сибири

Физическое моделирование режимов газового воздействия на нефтегазоконденсатных месторождениях Восточной Сибири

Miscible and Immiscible Gas-Injection Pilots in a Middle East Offshore Environment

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 18513, “A Case Study on Miscible and Immiscible Gas-Injection Pilots in a Middle East Carbonate Reservoir in an Offshore Environment,” by Jitendra Kumar, Pawan Agrawal, and Elyes Draoui, Abu Dhabi Marine Operating Company, prepared for the 2015 International Petroleum Technology Conference, Doha, Qatar, 7–9 December. The paper has not been peer reviewed. Hydrocarbon-gas injection improves microscopic-displacement efficiency and generally acts as pressure maintenance; however, unfavorable mobility ratio can affect the ultimate recovery negatively because of viscous fingering and gravity override. This paper describes a gas-injection pilot that has been implemented in offshore Middle East carbonate reservoirs (a second pilot is described in the complete paper) to assess injectivity, productivity, macroscopic-sweep efficiency, flow assurance, and operational efficiency in a field that has a long water-injection history. Introduction The carbonate field is part of the Lower Cretaceous Lower Lekhwair formation. The field is divided into A, B, and C reservoirs, 20 to 35 ft thick individually. Each reservoir is vertically separated by nonpay tight intervals of similar thickness, composed of argillaceous limestone, isolating each reservoir from the others. Depending on the reservoir, oolitic shoal facies can be more abundant. Near the flank area, the formation is water-wet, and, as one moves toward the crestal area, the formation becomes oil-wet. The reservoir fluid is undersaturated at initial pressure of 4,200 psig at datum depth and a temperature of 220°F. Oil gravity is 40 °API, and oil contains 1–2 mol% carbon dioxide and an insignificant amount of hydrogen sulfide. All three reservoirs have common contact and similar oil properties, with a strong compositional gradient. Production from the field started in the late 1960s through natural depletion, which indicated weak aquifer support. Before pilot implementation, laboratory experiments were performed to determine the feasibility of hydrocarbon-gas injection. Pressure/volume/temperature experiments showed that the minimum miscibility pressure (MMP) is approximately 4,500 psia, which is higher than initial reservoir pressure, but the crude oil has a strong swelling effect. Unsteady-state coreflood experiments performed with a 200-cm-long core showed a recovery of 70% for immiscible flood and a recovery of 92% for miscible flood. Full-field compositional simulation of gas injection incorporating a tuned equation of state indicated significant incremental oil and reasonable pressure support.

Utilization of Voronoi Gridding for Simulation of Heterogeneous Discrete Fracture Networks Using Outcrop and X-ray CT

In this paper, we propose a workflow to simulate fluid flow in discrete fracture networks. This includes fracture characterization using fractal theory and distribution of fracture aperture as determined by X-ray CT scanning of rough fracture surfaces. Voronoi grids or Perpendicular Bisector, PEBI, are then generated using a newly developed algorithm that conforms to fracture patterns as observed on fractured outcrop. Once the fractures and matrix have been gridded, the simulator is benchmarked against conventional commercial simulators. Voronoi grids are generated in a way to align Voronoi edges along fractures. Special treatment has to be taken to populate Voronoi nodes in order to avoid the distortion of Voronoi grids around fracture tips and fracture intersection points. A connection list including geologic information of Voronoi grids can then be generated as an input mesh file to simulate fluid flow using a finite volume discretization based reservoir simulator. Simple gas injection simulation examples show that discrete fractures with variable aperture in individual fractures and non-uniform orientation of the fracture system might be a barrier to fluid flow or enhance conductivity depending on aperture distribution and orientation of the fracture system relative to injector-producer pairs.

Control of Numerical Dispersion in Streamline-Based Simulations of Augmented Waterflooding

Summary Augmented waterflooding is when a component is coinjected with water to modify the fractional-flow curve. Examples include polymer flooding, surfactant injection, low-salinity waterflooding, and carbonated-water injection (including applications related to carbon dioxide storage). The numerical simulation of these processes is a challenge for several reasons: The appropriate physical behavior needs to be incorporated consistently into empirical models of the fractional flow, whereas the solutions should minimize numerical dispersion, allowing the correct and accurate tracking of compositional variations. Lower-order numerical simulations of these processes give excessive front smearing, requiring many thousands of gridblocks in one dimension to resolve the fronts adequately, rendering the predictions from 3D simulations dubious at best. These erroneous predictions are not caused by phase dispersion (the improper prediction of water velocity)—as in black-oil simulation, in which the effect is less significant—but occur because of the coupling of compositional dispersion with fractional flow. Small errors in composition alter the fractional flow, causing the development of incorrect wavespeeds. The same effect is also seen in compositional simulation of gas injection. We propose a simple method for streamline-based simulations that substantially reduces numerical dispersion. The method is rooted in the assumption of segregated flow within a gridblock. After comparing numerical and analytical results in one dimension, we implement the method into a 3D streamline-based simulator of polymer flooding that also incorporates a physically based model of the fluid rheology. We demonstrate that traditional simulation methods can vastly overestimate recovery, potentially leading to poor injection design and management decisions. We demonstrate the utility of our approach by suggesting optimal strategies for the design of polymer injection on the basis of our improved simulation technique.

Impurity mixing and radiation asymmetry in massive gas injection simulations of DIII-D

Simulations of neon massive gas injection into DIII-D are performed with the 3D MHD code NIMROD. The poloidal and toroidal distribution of the impurity source is varied. This report will focus on the effects of the source variation on impurity mixing and radiated power asymmetry. Even toroidally symmetric impurity injection is found to produce asymmetric radiated power due to asymmetric convective heat flux produced by the 1/1 mode. When the gas source is toroidally localized, the phase relationship between the mode and the source location is important, affecting both radiation peaking and impurity mixing. Under certain circumstances, a single, localized gas jet could produce better radiation symmetry during the disruption thermal quench than evenly distributed impurities.

Nonlinear Formulation Based on an Equation-of-State Free Method for Compositional Flow Simulation

Summary Compositional simulation is necessary for modeling complex enhanced oil recovery (EOR) processes. For accurate simulation of compositional processes, we need to resolve the coupling of the nonlinear conservation laws, which describe multiphase flow and transport, with the equilibrium phase behavior constraints. The complexity of the problem requires extensive computations and consumes significant time. This paper presents a new framework for the general compositional problem associated with multicomponent multiphase flow in porous media. Here, adaptive construction and interpolation using the supporting tie lines are used to obtain the phase state and the phase compositions. For the parameterization of the full solution of a complex compositional problem, we need only a limited number of supporting tie lines in the compositional space. The parameterized tie lines are triangulated using Delaunay tessellation, and natural-neighbor interpolation is used inside the simplexes. Then, the computation of the phase behavior in the course of a simulation becomes an iteration-free, table look-up procedure. The treatment of nonlinearities associated with complex thermodynamic behavior of the fluid is based on the new set of unknowns—tie-line parameters that allow for efficient representation of the subcritical region. For the supercritical region, we use the standard compositional variable set based on the overall composition. The efficiency and accuracy of the method are demonstrated for several multidimensional compositional problems of practical interest. In terms of the computational cost of the thermodynamic calculations, the proposed method shows results comparable to those of state-of-the-art techniques. Moreover, the method shows better nonlinear convergence in the case of near-miscible gas-injection simulation.

A segregated flow scheme to control numerical dispersion for multi-component flow simulations

One of the challenges for reservoir simulation is numerical dispersion. For waterflooding applications the effect is controlled due to the self-sharpening nature of a Buckley–Leverett shock. However, for multi-component flow simulations, incorrect wavespeeds can develop leading to the excessive smearing of fronts because of the coupling of compositional dispersion with the fractional flow. Rather than implementing a higher-order discretization method, we propose a simple scheme based on segregation-in-flow within a gridblock to control numerical dispersion. We extend the method originally proposed for polymer flooding to augmented waterflooding simulations in general as well as simulations of miscible or near miscible gas injection. For compositional simulations of gas injection, this is done through a coupled limited-flash/upstream-exclusion assumption. To test the scheme, an in-house streamline simulator has been modified and validated for modeling low-salinity floods as well as ternary two-phase displacements. Simulation results presented with and without segregation demonstrate the potential of the approach as a heuristic method to control numerical dispersion in multi-component flow simulations.

Numerical Simulation of Gas Injection for CBM Openhole Cavity Completion Considering the Coal Vertical Fracture System

A discrete element numerical model simulating the process of gas pressurization in coalbed methane wells is built based on UDEC software. The model considers the unique vertical fracture system of the coal. Simulates the distribution of effective stress, pore pressure and the node displacement vector around the wellbore in the process of pressurization under different terrestrial stress conditions. The analysis shows that, reservoir fluid flow and matrix deformation in the pressurization of cavity completion can be better represented by taking coal's unique fracture system into consideration. Coal reservoir with anisotropic stress is more prone to rupture and collapse than that under isotropic condition. In the vertical fracture system, the discrepancy of the fluid velocity will lead to differences in formation stress gradient and help generate shearing fracture. Tensile fractures’ formation and growing trend can be reflected by nodal displacement vector distribution.