Vortex Tool Research Articles

Study on Flow Characteristics of Venturi Accelerated Vortex Drainage Tool in Horizontal Gas Well

Vortex drainage gas recovery has been used to carry liquid from gas wells. However, the traditional vortex tools in gas wells cannot produce long effective distance spiral flow at a low gas flow rate, and their operating mechanism has not been thoroughly analyzed. In this paper, the venturi acceleration vortex tool for a horizontal gas well is designed to improve drainage performance. The tube drainage, the vortex tool, and the venturi accelerated vortex tool were applied in a horizontal tube to investigate their drainage capacities by a horizontal well multiphase flow experimental device. The influence of different gas flow rates and liquid flow rates on the length of the spiral flow and pressure drop produced by the three tools was analyzed. The results show that the vortex tool can convert the gas–liquid mixing flow into the gas–liquid separation flow, that is, the liquid flows spirally along the wall and the gas flows in the center of the horizontal tube. Compared with the vortex tool, the venturi accelerated vortex tool can form a longer and more stable spiral flow. The laminar spiral flow reduces the total pressure drop in the tube. The length of the spiral flow increases with the increase in the gas flow rate. With the increase in the liquid flow rate, the spiral flow is not clear because of the turbulent flow. The length of the spiral flow and the pressure drop for the venturi accelerated vortex tool with different gas and liquid flow rates are analyzed to guide the application of the tool. This study provides a new means for the drainage of a horizontal gas well and further clarifies the working mechanism of the vortex drainage tool.

Research on Mechanism & Applicability of Vortex Tool Process in Gas Well

At present, drainage gas recovery technology is usually used to solve gas well drainage problems in the development of lard gas fields at home and abroad. A large amount of the produced water discharged from the bottom hole effusion is discharged to the ground. In the process of lifting, processing and injection consumes a lot of energy and greatly increased the capital investment and gas production costs, more serious is greatly shortened the economic life of gas wells, while the water produced by the environment also caused serious pollution. In order to achieve high efficiency of gas well production, it is necessary to further study and develop new technology suitable for gas field development, which can improve water drive energy and lifting rate, reduce energy consumption and reduce pollution. For better application of eddy current drainage gas recovery tools, better play to its performance, it is necessary to determine the eddy current drainage gas recovery tools use after the change of the flow pattern, the research on the mechanism both liquid eddy current drainage gas recovery tool, to analyze its influence factors, and carry on the optimization of structure, thus improve the efficiency of gas drainage and production efficiency.

Experimental study of swirling flow pneumatic liquid-carrying characteristics in the vortex tool inserted tube under liquid loading conditions

Liquid unloading by vortex tool is one of the most important applications of swirling flow pneumatic conveying. However, due to swirl decay, the evolution of gas–liquid flow patterns and the dynamic characteristics of pressure drop downstream of the vortex tool are much more complex than those in non-swirling flow. In this study, the gas–liquid flow patterns and pressure drop inside the vortex tool inserted tube (ID = 60 mm) under liquid loading conditions were experimentally studied and compared with those of the plain tube. With the superficial gas velocities ranging from 0.5 to 6.0 m/s and superficial liquid velocities of 0.01, 0.02, and 0.04 m/s, the effects of the structural parameters and stages of vortex tools on the pressure drop were discussed. The experimental results reveal that three distinct swirling flow patterns can be identified downstream of the vortex tool, namely swirling gas column flow, swirling churn flow and swirling annular flow. The insertion of vortex tool facilitates an earlier transition of the churn flow to the annular flow, and the induced swirling flow can restrain the liquid from falling back. The helix angle of the corkscrew deflector has a more significant effect on the pressure drop than its length. By reducing the helix angle from 54° to 45°, the total pressure drop and downstream pressure gradient are significantly decreased, even lower than those of the plain tube. But the series combination of 54° and 45° vortex tools results in a significant increase in the downstream pressure gradient. Additionally, at low gas flow rate, negative frictional pressure drop occurs in both plain tube and vortex tool inserted tube. Hence, the new friction factor correlations were established respectively for the positive and negative friction regions in the cases of the tube with and without vortex tool, and most of the frictional pressure gradient predictions are within an error band less than 20%.

Evaluation model of downhole vortex tools drainage and gas recovery effects according to TOPSIS method

Highlights A new index for the evaluation of the effect of vortex tools is proposed An evaluation model (SCORE model) was developed to more intuitively predict the effectiveness of using vortex tools The effect of the vortex tools in the actual wells is consistent with the SCORE model prediction points. The SCORE model can predict the effects of vortex tools and provides reference values for determining whether vortex tools are suitable for actual gas field production.

Drainage effect of internal vortex tool based on experiment and numerical simulation

ABSTRACT The liquid loading at the bottom of horizontal gas well is a problem that has a significant influence on the productivity of gas well. Therefore, it is necessary to take some measures of drainage gas recovery to reduce liquid loading in wellbore and increase gas production. To evaluate the drainage effect of the internal vortex tool, which is a new drainage gas recovery tool, firstly, under the conditions of different water-gas ratios, a horizontal well laboratory simulation experiment device was used to simulate the flow state and liquid loading of the gas-liquid two-phase fluid in the wellbore before and after loading the internal vortex tool. The experimental results indicate that the internal vortex tool can effectively decrease wellbore liquid loading, improve wellbore fluid flow pattern and reduce production pressure drop. Secondly, the numerical simulation method is used to study the flow of gas-liquid two-phase and pressure drop amplitude under different gas and liquid flow conditions. Finally, the results of laboratory experiment were compared with numerical simulation, and it was found that the pressure drop amplitude error was between 6.18%~9.32%, both within 10%, which met the error requirements. It was proved that the application of internal vortex tool could effectively increase the productivity of gas wells.

Optimizing the structural parameters of downhole vortex tool in gas well using a genetic algorithm

Structural parameters of vortex tools affect the drainage of water producing gas wells, while previous research mostly focused on the optimization of individual parameters. This study aimed at establishing the optimal sizes of downhole vortex tools. The gas-liquid separation efficiency (SE) model and pressure loss model of the vortex tool were also established. A multi-objective genetic algorithm (GA) optimization process was designed to achieve the maximum SE and minimum pressure loss of the vortex tool. A sensitivity analysis was performed to investigate the impact of structural parameters on SE and pressure loss of vortex tools. It was found that an increase in the spindle diameter (DVT) and/or the helical height (HVT) and/or a decrease of the flow channel width (WFC) improved the SE of the vortex tool. In addition, reducing DVT and/or HVT and/or increasing WFC reduced the pressure loss of the vortex tool. A set of optimum combinations of structural parameters was obtained through GA with an average SE of 0.9982, an average pressure loss of 1513.3 Pa, and an average fitness function value of 0.0068. Field results showed that the optimized vortex tools were conducive for gas well drainage and improved gas production. An optimized method for designing the structural parameters in vortex tools has been proposed in this study. Our study findings are of great significance in improving the drainage capacity of water producing gas wells.

Gas–liquid two‐phase flow characteristics of the jet vortex drainage gas production tool based on computational fluid dynamics

AbstractThis study is aimed at the problems of traditional vortex tools in gas wells, including notable pressure losses and short effective distances. An organic combination of jet vortex drainage and gas production tools was designed and installed without additional power equipment. Based on the liquid film force balance model, gas–liquid two‐phase flow and turbulence models of the jet vortex tool were established with UG and Fluent flow simulation software. The gas–liquid mixture was analyzed before and after the jet vortex tool, and the flow trajectory, pressure loss, liquid volume fraction change, and change rate were examined. According to the simulation results, the comprehensive influence of each structural parameter on the effective working distance was optimized, and optimal structural parameters of the jet vortex tool were obtained. The results indicate that the jet vortex tool reduces the critical liquid‐carrying flow rate and pressure loss and increases the axial and initial velocities of the gas and liquid phases, combined with swirl tool distance model, the effective flow distance is increased correspondingly, and the liquid‐carrying capacity of the gas well is improved.

An orthogonal numerical simulation experiment study towards the decay characteristics and effective swirl length of the swirling flow in a vortex tool inserted tube

Studying the decay characteristics and effective swirl length of the gas-liquid two-phase swirling flow generated by vortex tools is of great significance for improving its drainage effect. The effective swirl length is a key parameter related to the working performance, installation spacing and downstream pressure dynamics of vortex tools. However, works addressing the effective swirl length are rare in the literature. In this research, the decay characteristics and effective swirl length of a swirling flow and the factors that affect the swirling flow are systematically investigated using the orthogonal numerical simulation experiment method. Good agreements are achieved between existing experimental data and the numerical results of this study. The range analysis results reveal that the helix angle, mandrel diameter and vane axial length play dominant roles in the initial swirl intensity. An increase in the helix angle results in a decrease in the initial swirl intensity, while the mandrel diameter has the opposite effect. The swirl intensity decay rate is mainly affected by the Reynolds number, helix angle and vane axial length; the decay rate has a negative correlation with the first two factors and a positive correlation with the third factor. On this basis, a comprehensive decay model of the swirl intensity is proposed after obtaining the correlations for the geometrical swirl intensity and swirl intensity decay rate. Furthermore, an effective swirl length evaluation method is established, and the optimal vortex tool structure of a typical gas well is obtained with a helix angle of 55°, a mandrel diameter of 38 mm, a vane axial length of 120 mm and a vane width of 15 mm.

Optimization analysis of structure parameters of downhole vortex tool based on CFD and orthogonal studies

Liquid loading is one of the most serious problems in the gas wells with low pressure and production. It limits the production severely, due to the high cost of other deliquification technologies. The downhole vortex tool is an economic and efficient way to alleviate the liquid loading, but the optimal efficiency conditions still not clearly. In this paper, gas–liquid two-phase flow passing through a downhole vortex tool is studied by numerical simulation to optimize the structural parameters (Helix angle, helix height, helix width) and operating envelope (superficial gas velocity and superficial gas velocity) of the vortex tool. The Euler–Euler approach and Reynolds stress turbulence model are used to calculate the vortex field. The experimental results show that the pressure gradient downstream of vortex tool agrees well with the numerical results. An orthogonal design method was used to evaluate the performance of the vortex tool with different structural and operating parameters. The range analysis results show that the optimal combination is A2B2C3D5E5(α = 45°, H = 6 mm, h = 15 mm, vsg = 18 m/s, vsl = 0.1 m/s), with the impact sensitively intensity to evaluate index of each factor as follows: A > E > B > D > C. The effective operating envelope of vortex tool is when superficial gas velocity range from 9 m/s to 16 m/s. The pressure gradient downstream of optimal tool decreased by about 20.3% compared to the original tool at the maximum value point.

The mechanism of drainage gas recovery and structure optimization of an internal vortex tool in a horizontal well

Effective drainage gas recovery technology is the key to solving the problem of the liquid loading of gas well and of enhanced gas recovery. An internal vortex tool is designed for solving the problem of liquid loading in horizontal wells. This study conducted a computational fluid dynamics analysis the efficiency of the drainage gas recovery of the tool in the horizontal well, to optimize the structure of the tool. The results show that most of the liquid film flows along the pipe wall in the internal vortex tool, and the gas flows through the central area of the pipe at a high speed with fog. The internal vortex tool can increase the gas phase velocity and separate the gas and liquid. The structural parameters of the internal vortex tool for minimum pressure loss and the maximum drainage efficiency is the same diameter as the tubing and casing for the runner diameter, 42.8° for the swirl angle, 8 mm for the helix height, 6 mm for helix width and 4 for the number of lead. The study on the flowing of a gas liquid swirling flow in the internal vortex tool proves the feasibility of its application in horizontal wells. It can provide theoretical guidance and a practical basis for efficient liquid loading using the internal vortex tool in the future.

Study on the gas–liquid annular vortex flow for liquid unloading of gas well

Vortex tool is a new technique for the liquid unloading in gas wells. But it lacks a mathematical model to describe and predict the effect of vortex tools. In the present work, according to the axial, radial and circumferential momentum balance of the gas phase and liquid phase, the governing equations of vortex flow model have been established. Then thickness of liquid film and gas and liquid vortex flow intensity as well as the pressure drop gradient can be calculated. The calculation results and the previous experiments indicate that the pressure drop of the gas–liquid flow can be reduced by 5% ~ 25% with the vortex tool, and the vortex flow model has an average relative difference of 6.01%. The model results show that there are two mechanisms for reducing the pressure drop under the vortex flow condition. In addition, the research results show that vortex tools with bigger helical angle will lead to higher vortex flow intensity. The decay rate of vortex flow intensity decreases along the pipe as liquid velocity increases and the vortex flow working distance can be calculated by the vortex intensity gradient and initial vortex flow intensity.

Dynamic analysis for two-phase vortex flow and optimization of vortex tools to unload liquid from gas wells

Vortex drainage gas recovery is a new technology to unload liquid from gas wells. However, its operating mechanism and efficiency are still not clearly understood, the dynamic analysis model in the wellbore two-phase vortex flow is still lacking. In this study, the forces of the liquid film in the wellbore gas-liquid vortex flow are analyzed based on the two-phase fluid dynamic theory. A dynamic analysis film model for prediction of the pressure drop in the wellbore two-phase vortex flow and the optimal helical angle of vortex tools is established. Besides, the physical simulation experimental facilities were set up and the wellbore two-phase vortex flow was obtained. Various parameters with vortex tools, including the wellbore pressure drop, the operating envelope and the critical flow rate, were examined. The influences of structure parameters of vortex tools on the drainage effect were analyzed. These structure parameters include the flow section of the flow channel, the leak-tightness around the flow channel and the helical angle. The vortex tool which has the best drainage effect was chosen and tested, and the extent of reduction of the critical flow rate with the optimal vortex tool was determined. Then, a liquid loading gas well in the field was chosen. Vortex tools were optimized and used in the wellbore of the gas well. The dynamic analysis model is verified by the experiment and field test. The results show that the dynamic analysis model of the liquid film in the wellbore two-phase vortex flow is reasonable. The effectiveness of vortex tools can be improved by enhancing the leak-tightness on both sides of the flow channel and reducing the flow section of the flow channel. After installing the optimal vortex tool, the wellbore pressure drop decreased by about 9.6%, the liquid flow rate increased by about 12.4% and the critical flow rate decreased by about 20%. The helical angle of the vortex tool has an optimal value, which can be calculated by using the dynamic analysis model. Research results may provide theoretical guidance for the optimization and design of vortex tools.

Dynamics and effective distance of gas–liquid two-phase swirling flow induced by vortex tools

Based on the mechanistic model of the two-phase swirling annular flow behavior, a calculation method for the effective distance of vortex tool is obtained by taking Kelvin–Helmholtz instability into account. The rationality of the proposed method is validated by comparing the predicted liquid film thickness and pressure under non-swirling flow with the commonly used correlations. Then, the influences of gas–liquid ratio, helix angle, and hub diameter of vortex tool on the liquid film thickness, pressure drop, and effective distance have been analyzed. Results show that the presence of the vortex tool causes the decrease in the liquid film thickness and increase in the pressure drop. The liquid film thickness increases gradually as the helix angle and the hub diameter increase, and the larger helix angle results in smaller pressure drop. The effective distance increases with an increase in the gas–liquid ratio and decreases with an increase in helix angle and hub diameter. A sudden decrease occurs when the helix angle exceeds 60°. The gas–liquid ratio and helix angle are more dominant factors than the hub diameter on the liquid film thickness, pressure drop, and effective distance.

Dynamic analysis of a liquid droplet and optimization of helical angles for vortex drainage gas recovery

Downhole vortex drainage gas recovery is a new gas production technology. So far, however, the forces and motions of liquid phase in the swirling flow field of wellbores during its field application have not been figured out. In this paper, the forces of liquid droplets in the swirling flow field of wellbores were analyzed on the basis of two-phase fluid dynamics theories. Then, the motion equations of fluid droplets along axial and radical directions were established. Magnitude comparison was performed on several typical acting forces, including Basset force, virtual mass force, Magnus force, Saffman force and Stokes force. Besides, the formula for calculating the optimal helical angle of vortex tools was established according to the principle that the vertical resultant force on fluid droplets should be the maximum. And afterwards, each acting force was comprehensively analyzed in terms of its origin, characteristics and direction based on the established force analysis model. Magnitude comparison indicates that the forces with less effect can be neglected, including virtual mass force, Basset force and convection volume force. Moreover, the vertically upward centrifugal force component occurs on the fluid droplets in swirling flow field instead of those in the conventional flow field of wellbores, which is favorable for the fluid droplets to move upward. The reliability of optimal helical angle calculation formula was verified by means of case analysis. It is demonstrated that with the decrease of well depth, the fluid-carrying capability of gas and the optimal helical angle increase. The research results in this paper have a guiding significance to the optimization design of downhole vortex tools and the field application of downhole vortex drainage gas recovery technology.

Numerical Simulation Research of the Influencing Factor of Vortex Tool Drainage Gas Recovery Technology

The problem of effusion in gas well bottom hole grows increasingly serious in the late exploitation of gas field. The technology of vortex drainage has good prospects because the tool is conveniently manufactured and environmentally friendly. Currently, the mechanism for the vortex drainage and the theory of fluid motion are still missing. Therefore, in order to further realize the flow field of bottom hole, verify drainage mechanism and optimize working conditions, the study established a three-dimensional structural model of vortex tools to simulate the progress of gas well drainage by using the CFD software Fluent. By monitoring the liquid content of wellhead, liquid’s radial distribution, observing the flowing state of gas-liquid and the path line, analyzes the influence of gas production rate, liquid producing capacity of wells and the main structure parameters of vortex tools (the length of the pitch of the helical blade and screw) on gas well flow field. The study revealed the working mechanism of vortex tools to facilitate the understanding of the nature of the vortex drainage process, guided the field how to select the preferred process conditions and provides the basis for optimizing the structure and provide theoretical basis for the application and the dynamic simulation of vortex drainage technology.

The Mechanism Study of Vortex Tools Drainage Gas Recovery of Gas Well

The liquid loading of gas well is an important issue in deep exploitation of natural gas. The technic of vortex drainage has good prospects because the tool construction and construction work is simple, the technic is environmental and efficient. Currently, the mechanism for the vortex drainage and the theory of fluid motion are still missing. Therefore, in order to further understand the downhole flow field, verify drainage mechanism and select best working conditions, based on computational fluid dynamics and mixture model of multiphase flow through Fluent, the study established a three-dimensional structural model of vortex tools and the numerical simulation has been done. By monitoring the wellhead and the radial distribution of the liquid content and observing the state of the gas-liquid flow and the path line, the study analyzed the influence on gas well flow field by vortex tool. The study revealed the working mechanism of vortex tools to facilitate understanding the nature of the vortex drainage process, guide how to select the preferred process conditions and provide theoretical basis for the application and the dynamics simulation of vortex drainage technology. Key words : The liquid loading of gas well; Vortex drainage; Multiphase flow; Numerical simulation