Numerical Simulation Technology Research Articles

An efficient hybrid methodology for optimization of CO2 Huff-n-Puff EOR and sequestration in tight oil reservoirs

CO2 Huff-n-Puff is one of the effective enhanced oil recovery (EOR) methods in tight oil reservoirs, which is also attractive to sequestrating CO2 underground. Therefore, CO2 Huff-n-Puff EOR and sequestration project is particularly important both for oil and gas industry and environmental protection field. However, the technique has not gained industry-wide adoption partly due to knowledge gaps in efficient optimization of CO2 Huff-n-Puff EOR and sequestration using compositional numerical simulation. The purpose of this work is to propose an efficient hybrid optimization methodology which is called proxy-model-based optimization with initialization constraint. Two cases for single objective optimization and multi-objective co-optimization of CO2 Huff-n-Puff EOR and sequestration with two objective functions were investigated. Our findings suggest that the optimization performance of proxy-model-based optimization is highly dependent on the relative errors of the proxy model compared with simulator-based optimization. The optimization performance of proxy-model-based optimization with initialization constraint is 4∼10 % lower than that of simulator-based optimization, but the reduction in the number of simulations and improving the robustness of a stochastic optimizer are very attractive. In addition, different objective functions and optimization mode have different sensitive parameters. To the best of our knowledge, this is the first time to conduct single/multi-objective optimization of CO2 Huff-n-Puff EOR and sequestration in tight oil reservoirs based on numerical simulation technology, method of response surface experimental design and single/multi-objective particle swarm optimization algorithm. We believe the proposed methodology in this work is efficient especially for large reservoir simulations and rapid prediction of optimization schemes.

An Analysis of the Perspective Road Design Scheme Around Zhangzhou Olympic Sports Center

City events take place in the Zhangzhou Olympic Sports Center, resulting in traffic. Hence, this study analyzed the road planning and design around Zhangzhou Olympic Sports Center through traffic demand forecasting. The simulated data and road plan underwent macro prediction model technology and numerical simulation technology through Emme and TransCAD. The regional road network structure, traffic demand forecast, plane, longitudinal section, and cross-sectional program selection were investigated to determine a reasonable design program. While urban development programs were implemented, the study ensured an increase in the city's economic growth alongside the guaranteed value of citizens’ welfare.

Numerical simulation study on the drag reduction characteristics of grooves-microbubbles coupling surfaces

Surface drag reduction technologies can significantly reduce the resistance during ship navigation, enhancing speed, efficiency and adaptability under various operating conditions. This paper uses numerical simulation technology to analyze the drag reduction characteristics of grooved and grooves-microbubbles coupling surface, focusing on the effects of groove width, gas flow rate, and liquid flow velocity on the drag reduction performance. The research results indicate that the grooved surface is suitable for full surface drag reduction at velocity below 3 m/s with a maximum drag reduction rate of 4.02%. Microbubbles can greatly improve the drag reduction effect of the grooved surface, and the drag reduction effect of the coupling surface gradually increases with the gas flow rate increases. The maximum drag reduction rate can reach 89.86% at the gas inlet velocity of 1 m/s. The liquid flow velocity has a significant impact on the drag reduction. In both the groove model and the coupling model, the drag reduction rate initially rises and then declines with the liquid flow velocity increases.

Investigation of seeding performance of a novel high-speed precision seed metering device based on numerical simulation and high-speed camera

Numerical simulation and high-speed photography technology are used in this work to obtain the key factors affecting the seeding performance of a novel high-speed centrifugal filling-cleaning precision seeding metering device under different conditions. The effects of key parameters, including seed-metering diversion turbine structure, dynamic wind pressure, seed quantity, and ground speed, on the seeding performance of the high-speed seed metering device are investigated. The results show that a diversion turbine structure with diversion and controlled disturbance flow increases seed pressure and enhances the filling process. Meanwhile, a correlation between dynamic wind pressure and seed movement velocity is established using a high-speed camera-based experimental approach. Maintaining 24 internal seeds is crucial to guaranteeing the quality of feed index. Specifically, under the simulation conditions, when the ground speed is 14 km/h (corresponding to a rotation speed of 194.5 rpm), the corresponding dynamic wind pressure is identified as 1.5 kPa, the corresponding seed plate speed is 2 m/s, the corresponding optimal feeding rate should be maintained at about 14 seeds/s, and the seed inlet velocity is 3 m/s. Additionally, the results of comprehensive bench and field seeding performance experiments demonstrate that, as the seeding speed increases, there is no apparent seeding performance decline, and even under high-speed operational conditions, the quality of feed index under different ground speeds exceeds 90%.

A study to analyze the importance of establishing a mathematical model for teaching college physics

Abstract Numerical simulation technology to assist the teaching of university physics is a higher education to continuously adapts to the social development of its own needs. This paper classifies the common forms of university physics courses involving numerical computation, explores the current computer simulation in physics teaching, and establishes the development process of the university physics computer numerical computation simulation program. Numerical simulation technology is applied to the design of university physics teaching, and two examples of numerical simulation technology assisting university physics teaching are designed from two cases of grating diffraction intensity distribution and gas diffusion based on Matlab. In Example N = 10, the light intensity distribution of diffraction grating with different slit numbers is analyzed by numerical simulation, and it is obtained that at 1, there are 9 minima between two adjacent main maxima, 8 sub-maxima, and the maximum value is 100, which verifies the theoretical results of the physical derivation of the grating diffraction intensity distribution. In the exposition, mathematical modeling is combined with examples to show that mathematical modeling can greatly exert the role of mathematical ideas in physics teaching, simplify physics teaching, and further cultivate students’ ability to solve practical problems.

Numerical Simulation and Wear Resistance Property of Ni-Based Alloy Coating on the Surface of Ti-6Al-4V Substrate

Laser cladding is a new technology to improve the wear resistance or corrosion resistance properties of metal parts. A finite element model of laser cladding coating was established by numerical simulation technology. The temperature field distribution was studied and analyzed during the laser cladding process at three different scanning speeds and three different laser powers. A Ni-based coating was also fabricated on the substrate by a CO2 laser. The optimum parameters of the laser cladding were selected and compared with the melt pool depth and width of the Ni-based coating. Then, the cooling rate, temperature gradient, temperature and stress fields were calculated and analyzed. The growth mechanism of the crystal structure was analyzed by scanning electron microscope (SEM). The wear resistance of the Ni-based coating was measured by a friction and wear testing machine. The results showed that the optimal parameters were laser power 1600 W and scanning speed 3 mm/s. The temperature trends at different locations were similar. The calculated maximum residual stress was 0.157 GPa. The stress concentration appeared near the surface and both sides of the cladding layer. From the coating’s microstructure, it could be seen that it contained a large number of columnar dendrites, and the crystal size gradually decreased with the increase of cooling rate. The wear rates of the Ti-6Al-4V (TC4) substrate and the Ni-based coating were 6.98 mm3/(N·m) and 3.45 mm3/(N·m), respectively. The Ni-based layer had a low wear rate and good wear resistance, which is helpful to obtain good friction and wear resistance of TC4 substrates.

Fast prediction method of propeller hydrodynamic performance based on SPF-LSTM

In order to realize fast and accurate prediction of hydrodynamic performance of UUV propeller, a hydrodynamic performance prediction model based on SPF-LSTM neural network was proposed in this paper, which combined with real propeller flow test and CFD numerical simulation technology. The model comprehensively considered the test data of real paddle and the simulation data based on CFD numerical simulation, and adopted the Sample penalty factor (SPF) to optimize the initial weight of the model, adjust the sensitivity of the model to different samples, and further improve the prediction accuracy. The experimental results show that the prediction results of this model are in good agreement with the test data of real propeller, and the calculation period is very short and the efficiency is high, which meets the requirement of real-time and accurate prediction of the open water performance of propeller.

Mechanistic Study and Optimization of High Water Cut Phase Management Strategies in Fracture-Vuggy Carbonate Reservoirs with Bottom Water

Fracture-vuggy carbonate reservoirs commonly exhibit sufficient bottom water energy and are characterized by fractures or other interconnected channels with bottom water, which can easily cause high water cut in oil wells during production. The main reasons are as follows: firstly, bottom water coning leads to water flooding. Secondly, artificial water injection flooding fails and shows high water cut in oil production. This paper further clarifies the causes of high water cut in fractured-vuggy carbonate reservoirs and explores rational and feasible management strategies to improve the current water flooding situation and reduce the comprehensive water cut in oil wells. In this paper, numerical simulation technology is used to establish a mechanism model based on the actual reservoir conditions. By comparing the development effects of four bottom water suppression measures, including the adjustment of flow channel, artificial barriers, adjustment of flow potential and gas injection, the optimal measure is selected and the relevant parameters are optimized. Building upon this, further optimization of water injection methods is conducted to explore comprehensive management strategies for enhancing the water flooding effect during high water cut periods. The research demonstrates that bottom water can be effectively inhibited by artificial barriers, leading to an expansion of the swept volume of water injection and achieving the goal of improving the high water cut condition in carbonate reservoirs. Optimal implementation of artificial barriers occurs when the water cut reaches around 80%. Specifically, positioning barriers at the bottom of perforations and setting the barrier radius at 0.15–0.2 times the well spacing obtain the most favorable results. Additionally, short-term injection with long-term shut-in, identified through cyclic water injection simulations, exhibits superior oil recovery enhancement. Validation conducted in a practical field of a fractured carbonate reservoir over a five-year period has led to a substantial increase in oil production by 5.6 × 104 t and a 12% reduction in water cut. The research approach and methodology presented in this paper can provide valuable insights and serve as a reference for the development of high water cut periods in fractured-vuggy carbonate reservoirs.

Gas–solid reactor optimization based on EMMS-DPM simulation and machine learning

Design, scaling-up, and optimization of industrial reactors mainly depend on step-by-step experiments and engineering experience, which is usually time-consuming, high cost, and high risk. Although numerical simulation can reproduce high resolution details of hydrodynamics, thermal transfer, and reaction process in reactors, it is still challenging for industrial reactors due to huge computational cost. In this study, by combining the numerical simulation and artificial intelligence (AI) technology of machine learning (ML), a method is proposed to efficiently predict and optimize the performance of industrial reactors. A gas–solid fluidization reactor for the methanol to olefins process is taken as an example. 1500 cases under different conditions are simulated by the coarse-grain discrete particle method based on the Energy-Minimization Multi-Scale model, and thus, the reactor performance data set is constructed. To develop an efficient reactor performance prediction model influenced by multiple factors, the ML method is established including the ensemble learning strategy and automatic hyperparameter optimization technique, which has better performance than the methods based on the artificial neural network. Furthermore, the operating conditions for highest yield of ethylene and propylene or lowest pressure drop are searched with the particle swarm optimization algorithm due to its strength to solve non-linear optimization problems. Results show that decreasing the methanol inflow rate and increasing the catalyst inventory can maximize the yield, while decreasing methanol the inflow rate and reducing the catalyst inventory can minimize the pressure drop. The two objectives are thus conflicting, and the practical operations need to be compromised under different circumstance.

Design and simulation of anti-sloshing baffles applied to detumbling payload propellant tanks

The method to suppress the liquid sloshing in the tank applied to the jet detumbling payload is investigated in this study. Among all kinds of anti-sloshing structures, the symmetrical annular baffle was chosen due to the features of impact on the payload’s tank. The damped mass-spring liquid sloshing model established is used to compare the damping ratio of the baffle with different baffle layers and different baffle heights. Using FLUENT software, based on VOF (volume of fluid) numerical simulation technology, the damping effect of baffles with different layers and heights is simulated. The results show that 3-layer 15mm or 4-layer 10mm baffles can effectively reduce the influence of liquid sloshing. The damping ratio of the storage tank with a 3-layer 15mm anti-sloshing baffle is at least 18.3 times that of a smooth tank, and the damping ratio of the tank with a 4-layer 10mm anti-sloshing baffle is at least 18.7 times that of a smooth tank.

Bending deformation control in a laser-welded long straight structure by elastic pre-bending technique

Longitudinal bending deformation is the most typical mode of welding deformation in long-straight welded structures with asymmetric cross-sections. It is very critical for manufacturing accuracy to control the longitudinal bending deformation during the welding assembly stage. The objective of this study is to propose an elastic pre-bending technique to control the longitudinal bending deformation induced by welding heat input. Both numerical simulation technology and experimental method are employed to investigate the longitudinal bending deformation in a large-straight structure made of SUS304 stainless steel. In the current study, the effectiveness of the proposed elastic pre-bending method is verified by experiment. Simulation results show that the longitudinal bending deformation caused by welding could be reduced by >90 % by setting an appropriate value of pre-bending deformation. In addition, based on theoretical analysis and simulation results, the control mechanism of longitudinal bending deformation is clarified.

Study on the Countermeasures and Mechanism of Balanced Utilization in Multilayer Reservoirs at Ultra-High Water Cut Period

After entering the ultra-high water cut stage of multilayer oil reservoirs, the remaining oil is highly dispersed. Due to the continuous development of general water injection, the generation of advantageous channels makes interlayer contradictions more prominent, and the differences in the utilization between different layers are even greater. After the water drive development of multilayer oil reservoirs enters the ultra-high water cut stage, the development effect deteriorates year by year. Layer restructuring is an effective method of improving the water injection development effect and increasing the degree of utilization. In essence, its goal is to achieve balanced utilization for multiple development layers to increase the degree of recovery. This article mainly employs physical simulation experiments combined with reservoir numerical simulation technology to jointly study the effects of different equilibrium production strategies in the ultra-high water cut period of multilayer oil reservoirs and their mechanism of action based on the remaining oil distribution field and streamline field. As a specific implementation, we use large-plate physical simulation to demonstrate the effectiveness of the rotational injection and production strategy, and to supplement the physical simulation experiment with a reservoir numerical simulation model, we analyze the mechanism of different balanced production strategies. The research results for the combination of physical simulation experiments and numerical simulation experiments show that the combined strategy of rotary injection and rotary production is the most effective method for use in multilayer and ultra-high water cut oil reservoirs. The displacement effect of the high-permeability layer is better, and the increase in the recovery degree is relatively large, while the displacement effect of the low-permeability layer is relatively weak. After conventional water drive oil recovery, the remaining oil mainly exists in the edge area of the research area. However, the use of three-dimensional well network injection wheel recovery changes the streamline field, produces the effect of fluid flow diversion, expands the water drive sweep coefficient, and improves the recovery rate. Chemical plugging can effectively replace water drive oil recovery and will become the main method for improving the recovery rate of such reservoirs in the lower part.

Damage identification and failure morphological reconstruction for engineering rock mass

By and large, the traditional CT technology cannot involve the important problems of intrinsic damage identification and reconstruction of large-scale engineering rock mass. In the light of the numerical simulation technology, the digital image processing technology and the three-dimensional reconstruction technology, a kind of numerical computed tomography method is proposed. On the basis of numerical simulation, the external program of the characteristic variable of rock mass damage and failure is called to generate the cloud map model of rock mass damage and failure. In addition, the sequence layered profile images are created by automatically cutting the cloud map model via the self-complied program, as well as adopting the digital image processing technology for batch cropping, batch gray-scale and binarization processing. Eventually, the three-dimensional reconstruction technology is employed to reconstruct the spatial distribution morphology of the internal damage and failure of rock mass. At that point, the proposed method is applied to apparently exhibit the evolution morphology of spatial distribution of the Rm 417 tunnel failure area, and effectively reveal the intrinsic connection of the Rm 417 tunnel failure, such as the location, evolution path and morphology. Consequently, the validity and reliability of the numerical computed tomography method are verified, which has satisfactory applicability and applied values.

Crashworthiness optimisation design of novel nested structures

In order to improve the crashworthiness of the novel circular-vein branched nested tube (CVBNT) proposed in recent research work, the crashworthiness design is optimised in this paper. Based on numerical simulation technology, the finite element model under transverse quasi-static compression of CVBNT is first established and effectively verified. Then, the energy absorption characteristics of CVBNT and different nested tubes were compared and analysed to reveal the excellent energy absorption performance of CVBNT. Finally, the structural design and the cross-sectional thickness optimisation of CVBNT are carried out. The results show that CVBNT has better energy absorption capacity than other nested tubes. The parameters N and γ have an important influence on the crashworthiness of CVBNT, and when N = 6, γ = 0.5 is the best choice in favour of its crashworthiness. At the same time, the optimisation of cross-section thickness effectively improves the crashworthiness of CVBNT.

Effect of a Double-Machine Parallel Air Curtain on Wind Flow in an Underground Roadway of a Coal Mine

In order to study the effect of a double-machine parallel circulation air curtain in intercepting wind flow in a mine roadway, the air curtain jet angle and full fan pressure were analyzed. Taking a metal mine roadway as the engineering background, Fluent numerical simulation technology was used to establish an equi-proportional physical model of the original roadway, and a K45-6 axial flow fan was selected to numerically simulate the flow field inside the original roadway, which was analyzed from three aspects: isolation pressure difference, air leakage volume and wind choke rate. The results show that when the full pressure of the fan is fixed, with an increase in the jet angle of the air curtain, the separation pressure difference and the wind choke rate show a trend of first increasing and then decreasing, and the air leakage volume shows a trend of first decreasing and then increasing. With an increase in the air curtain jet angle, the air curtain convergence gradually forms a complete air curtain, but when the air curtain jet angle continues to increase, the air curtain cannot effectively block the wind flow due to the transverse pressure from the roadway. When the jet angle is too small or the full pressure of the fan is too large, the phenomenon of induced air flow will occur, and the two-machine parallel air curtain will direct the air downstream of the roadway to upstream and no longer intercept the roadway air flow. After comprehensive analysis, the effect of wind control is obvious to set up a double-parallel air curtain in the roadway, and the optimal combination of the roadway air curtain is 30° for the full pressure blade of the fan and 30° for the jet angle.

Parameter identification and model prediction path following control of underactuated AUV: Methodology and experimental verification

This paper explores the integrated optimal control scheme from the identification of underactuated autonomous underwater vehicle (AUV) system dynamics model parameters to the application of Model Predictive Control (MPC) technology in underactuated AUV motion control, and presents the simulation and field test results. First, the AUV kinematics and dynamics models are introduced to represent the horizontal plane motion characteristics. Based on Computational Fluid Dynamics (CFD) numerical simulation and overset mesh technology, AUV plane motion is simulated to determine the unknown hydrodynamic coefficients in the model, and the accuracy of the mathematical model is validated by comparing the maneuverability simulation and field test results. After that, an adaptive line-of-sight (ALOS) guiding algorithm with exponentially variable forward distance is utilized in the guidance layer to reconcile the rapidity and stability of tracking. The path following problem is formulated as an MPC optimization problem that takes into account multiple realistic constraints and then converted into a standard convex quadratic programming structure, permitting for online real-time optimization. Simulation and field test results indicate that the control algorithm proposed in this paper provides a more effective control strategy than the traditional LOS+PID controller in tracking effect and robustness.

Numerical Simulation Study of Creeping Rock Formation in Jin X Fracture Block of Jingqiu Oilfield

The Jin X fault block in Jing qiu Oilfield, as the main oil producing area of Huabei Oilfield.At present, there are a total of 141 wells drilled in this block, and 97 wells with damaged casing have been transformed;The casing transformation of wells has led to an increase in abandoned wells in this block, resulting in serious damage to the well network. The JinX fault block has a large number of damaged wells. The number of abandoned wells in this area has increased due to casing deformation, resulting in severe damage to the well network and high degree of casing damage. Among them,71 wells have been severely damaged due to casing deformation, such as scrapping, channeling, and pipe sticking, which have affected production, accounting for 73.2%. This has seriously affected the efficiency of oilfield production in the region.Previous statistics show that most of the casing deformation sections are in the paste salt formation, and the form of casing deformation and casing damage is mainly deformation. In order to investigate the mechanism of casing damage in the casing section, this paper establishes the creep equation of the casing layer in JinX block by conducting microstructure analysis of the casing layer and creep experiments in the casing layer, and then establishes a creep calculation model by using 3D numerical simulation technology, combining geological structure and well type conditions. The creep calculation model is then used to analyze the creep pattern under different conditions through simulation calculations, thus providing a reference for formulating effective casing loss prevention and control measures for the Jin X fault block.

Effect of Inclined Orifice in Air Impingement Freezer on Heat Transfer Characteristics of Steel Strip Surface

In order to improve the heat transfer characteristics of the air impingement freezer, an impingement freezer experimental table was designed as the research object in this paper. Numerical simulation technology was used to simulate the impingement freezer experimental table on the basis of test verification. When the other structural parameters in the impingement freezer experimental table were constant, the effect of the inclination angle of the orifice plate (θ = 60°, 65°, 70°, 75°, 80°, 85°, and 90°) on the heat transfer characteristics of a steel strip surface was analyzed by two aspects, the average Nusselt number and the heat transfer uniformity. The results showed that with the increase in the inclination angle of the orifice plate (60° ≤ θ ≤ 90°), the average Nusselt number of the steel strip surface was increased by 19.39%, and the heat transfer uniformity index was decreased by 33.69%. When θ = 90°, the average Nusselt number on steel strip was the maximum, which was 263.68, and the heat transfer uniformity index was the minimum, which was 0.2039. Therefore, the heat transfer intensity and heat transfer uniformity in the air impingement freezer could be improved when the inclination angle of the orifice plates was 90°. This helps to improve the output of the air impingement freezer, reduce energy consumption, and improve the quality of frozen food.

A New Type of Oxidation Air Bubble Breaking and Detention Device with Wing Span Baffle Structure Numerical simulation research

Taking the limestone gypsum wet desulfurization oxidation air duct of a 660 MW coal-fired unit in a power generation enterprise as the research object, a new type of oxidation air bubble crushing and retention device with a wing span baffle structure was simulated and optimized using CFD numerical simulation technology. The results showed that the retention time of bubbles in the slurry in the final design scheme was about 10.4 seconds, significantly better than the initial scheme’s 8.5 seconds and the comparison scheme 1’s 6.5 seconds. The new oxidation air bubble crushing and retention device significantly increases the retention time of oxidation air bubbles in the slurry, reduces the size of oxidation air bubbles, and improves the distribution uniformity of oxidation air in the slurry pool.

Dynamic Monitoring and Analysis of Mining Land Subsidence in Multiple Coal Seams in the Ehuobulake Coal Mine Based on FLAC3D and SBAS-InSAR Technology

Aiming at the land subsidence problem caused by multiple coal seam mining in the Ehuobulake Coal Mine, this paper, considering the geological conditions of the first and fifth layers of coal, adopts the method of combining FLAC3D numerical simulation and SBAS-InSAR technology to analyze the dynamic evolution law of land subsidence amount and range under multiple coal seam repeated mining conditions. The reliability of the technology is verified by the field GPS monitoring data. The results show that, under the mining condition of multiple coal seams in the Ehuobulake Coal Mine, the land subsidence presents obvious asymmetry, and the size and range of the land subsidence in the mining area further increase due to the mining of lower layer coal. FLAC3D simulation results show that the maximum land subsidence is −211.8 mm. The results of SBAS-InSAR monitoring show that the maximum land subsidence is −225 mm, and the land subsidence obtained by the two methods has a high degree of fitting. The method of combining FLAC3D and InSAR technology can accurately and reliably monitor and analyze the land subsidence under the repeated mining of multiple coal seams in the mining area. It can provide effective guidance for the stability analysis of mined-out areas and the prediction of the influence of repeated mining on ground deformation.