Oil Flow Patterns Research Articles

Study of perforated well productivity by a multi-scale coupling flow model with Darcy-brinkman-Navier/Stokes

The study of oil and gas flow patterns after perforation completion is essential for well productivity prediction and solutions optimization. Due to the multi-scale flow characteristics of production fluids after perforation completion, we have developed a multi-scale coupled flow model incorporating Darcy, Brinkman, and Navier/Stokes equations based on mass conservation and pressure equilibrium principles. The oil and gas flow after perforation completion is simulated, and the multi-scale coupled model is solved by numerical methods, revealing the flow law of oil and gas in the multi-scale space formed by perforation. Additionally, sensitivity analysis on factors influencing perforation completion productivity was conducted. Results indicate that the most influential parameters on well productivity, in descending order, are: blocking perforation permeability > perforation diameter > perforation density > perforation depth > perforation phase > crushed zone thickness. The selection of appropriate internal flow models for perforations is critical for accurate well productivity estimation. Given the significant impact of perforation permeability on completion productivity, measures should be taken to prevent perforation blockage during production, and clear blockages promptly upon detection. This research provides a theoretical foundation for rational selection of perforation methods, gun bullets, perforation parameters, and completion techniques.

Three-dimensional finite element analysis of turbulent crude oil flow and solid particle deposition patterns in circular curved pipelines

This study presents a numerical investigation of turbulent crude oil flows in circular curved pipelines, with a focus on the deposition patterns of solid particles within the fluid. Simulations were conducted using the Reynolds–Averaged Navier–Stokes equations coupled with the k–ε turbulence model to examine the influence of structural characteristics, such as bend curvature angle and bend curvature radius, on flow dynamics and particle deposition. The results reveal that the complex flow patterns generated by these geometric features significantly affect pressure gradients and particle trajectories. Specifically, the study shows that turbulent flows within bends exhibit intricate behaviors, with deposition patterns being strongly influenced by the pipeline’s geometric parameters. Sand particles, commonly present in petroleum flows, are found to be more effectively transported in pipes with larger curvature angles, while they exhibit a higher propensity to settle at smaller curvature angles and larger bend curvature radii. Furthermore, the simulations indicate that the majority of deposited particles accumulate on the inner wall immediately downstream of the elbow entrance.

Experimental investigation on flow patterns and pressure gradients of shale oil–water flow in a horizontal pipe

With the growing demand for hydrocarbon resources and the depletion of conventional oil and gas reservoirs, the development of shale oil will become popular. As the shale oil fields gradually enter the middle and late stages of exploitation, the water content reaches as high as 60–80 %. Analyzing the flow characteristics of shale oi–water flow during high water content can help optimize the range of flow parameters and improve pipeline transportation efficiency. However, research on shale oil–water flow patterns and pressure drop prediction models is still lacking. Therefore, this work conducted shale oil–water flow experiments in the multi-test section pipe flow loop, considering the temperatures (40–70 °C), mixture velocity (0.2–1.2 m/s), and water contents (60–80 %). The flow patterns of shale oil–water flow are studied, and the flow pattern maps are created. Moreover, the influence factors on pressure gradient are analyzed, including pipe diameter, water content, mixture velocity, and temperature. Eventually, the pressure drop prediction models are modified based on the pressure gradient and holdup experimental data. The results show that a thin oil film and an oil-sticking layer are adhered to the pipe wall at 40 °C and 50 °C, respectively. The mixture velocity increased from 0.4 m/s to 1.2 m/s, and the pressure gradient increased by 69.89 % when the temperature and water content are constant. The lubrication coefficient is introduced in stratified flow (ST) and three-phase stratified flow (TPS) models, and the pipe flow friction coefficient is modified in dispersed flow (DF) and intermittent flow (IF) models. Moreover, the average relative deviations between experimental data and calculated values of ST, TPS, DF, and IF modified models are 4.49 %, 4.23 %, 4.40 % and 5.17 %, respectively. Therefore, surface wettability reduces the friction between the oil phase and the pipe wall, and the oil film and oil-sticking layer increase the pipe flow resistance.

Two-phase oil and water flow pattern identification in vertical pipes applying long short-term memory networks

Accurate biphasic flow pattern recognition is essential in the design of coatings for the oil and gas sector because it enables engineers to create materials that are tailored to specific flow conditions. This results in enhanced corrosion protection, erosion resistance, flow efficiency, and overall performance of equipment and infrastructure in the challenging environments of the oil and gas industry. The development of flow maps has been based on empirical correlations that incorporate characteristics such as superficial velocities, volume fractions, and physical properties such as the density and viscosity of the analyzed substances. In addition, geometric parameters such as the inclination and the internal diameter of the pipes are considered. However, due to the difficult working conditions on offshore platforms and the limitations in monitoring internal flow patterns, technological advances have been implemented to improve this process using artificial intelligence techniques. In this context, this study proposes using a long-term memory (LSTM) recurrent neural network to predict the flow patterns generated in vertical pipes. This LSTM network was trained and validated using data obtained from a literature database. The results obtained showed that the model has a prediction error of less than 1%. These technological advances represent an important step towards optimizing the flow pattern identification process in the hydrocarbons industry. By leveraging the capabilities of artificial intelligence, more accurate and reliable forecasts can be obtained, enabling informed decisions and improving the efficiency and safety of operations.

Identification of oil–water-gas flow patterns by super-sparse near-infrared wavelengths sensor

This paper puts forward a method of using two wavelengths of near-infrared light to identify the oil–gas-water mixed flow patterns. Propose a new method of multiple correlation algorithm (MCA) to solve the sensor super-sparse representation problem. Use MCA results as input layer parameters, use BP neural network to train the voltage signal and identify different flow patterns. The experimental results show that the recognition degrees of water, oil bubble, and oil flow patterns have reached 96.77%, 98.39%, and 100%, respectively, and the recognition rate of the water–gas phase has 78.38%. Using a correction model can further improve the accuracy. Test the samples with water cut from 90% to 70%, and the average RMSE = 1.59e-2. This method can be applied to the detection of the water cut of crude oil in oil fields and has a certain reference value for the wavelength selection of near-infrared light sensors.

A research on a GA-BP neural network based model for predicting patterns of oil-water two-phase flow in horizontal wells

At present, unconventional oil reservoirs are usually exploited by means of horizontal wells. However, due to the influence of multiple factors such as well deviation, oil flowrate and water flowrate, the distribution (flow pattern) of oil and water in a wellbore is complex. In addition, an accuracy of flow pattern identification is also vital for accurately interpreting the oil-water two-phase production profile of a horizontal well. Therefore, the research on flow pattern prediction of wellbores is of great application significance. Firstly, at normal pressure and temperature, based on the multiphase flow simulation experiment device, a transparent glass wellbore with a diameter similar to the actual downhole well was used to carry out oil-water two-phase simulation experiments with different well deviations, different flowrates and different water cuts, while visual observation and whole-process HD video recording of oil-water flow states were performed. Secondly, with reference to the typical horizontal well oil-water two-phase theoretical flow pattern, the flow patterns under different experimental conditions were identified, and the distribution diagram of flow patterns at four well deviation angles was drawn. Then, the GA-BP neural network was used for learning and prediction of experimental flow pattern data, and a model for predicting four experimental flow patterns was established to realize the flow pattern prediction under different well deviations and different flowrates in horizontal well. Finally, the above prediction model was verified based on 24 data points of two sample wells. After comparison with logging data, it was found that the accuracy of identifying flow patterns through the prediction model was high, and the overall coincidence rate reached up to 87.25%, indicating that the prediction model met the requirements for interpretation of actual logging data.

Identification of Oil and Gas Two-Phase Flow Patterns in Aero-Engine Bearing Chambers Based on Kriging Method

The identification of the flow pattern within the bearing chamber's oil and gas two-phase flow is crucial for its lubrication design. Aiming at the lack of accuracy and universality of the current bearing chamber oil and gas two-phase flow pattern recognition, this paper introduces a new method for recognising oil and gas two-phase flow patterns based on the Kriging model. In this paper, the oil-gas two-phase flow field in the bearing chamber is modelled in Comsol simulation software using the level set-k- ε model. Subsequently, the finite element analysis results were used as samples to fit the Kriging model, and the effects of different variables on the flow pattern were analysed and compared with the actual results. The results demonstrate that the flow pattern discrimination results fitted by the Kriging model exhibit higher accuracy and greater generalisability. This holds significant implications for future lubrication and structural design of bearing chambers.

A transient numerical study for heat transfer and flow characteristics of dimpled piston cooling gallery of a diesel engine

Piston cooling gallery is an effective cooling method to achieve an acceptable piston temperature field. This paper aims to analyze the effects of teardrop dimples size and dimple head-and-tail orientation on flow and heat transfer inside the cooling gallery. To do so, the computational fluid dynamics model for galleries with different teardrop dimples were established. The results indicate that the local oil flow patterns in the axial and circumferential directions are affected by the dimples. Compared with smooth gallery, the presence of dimple enlarges the fluid charge ratio (FCR). Specifically, when radius of teardrop shaped dimples are R2 and R3 respectively, their corresponding gallery FCRs achieve 55% and 58%. Further, the variation in FCR makes a difference in the distribution of heat transfer, an in-depth analysis finds the dimples increase the heat transfer area between the gallery surface and the oil and simultaneously reduce the space of oil suspending in the gallery. Therefore, the heat transfer coefficient of a dimpled gallery is always greater than that of the smooth gallery, with the maximum improvement of 2.42%. Moreover, the change of heat transfer distribution reconstructs the heat transfer uniformity of the cooling gallery, with the maximum improvement of 24.25%.

Research on flow pattern of low temperature lubrication flow field of rotating disk based on MPS method

Special vehicles often work in low temperature environment. Nevertheless, the lubrication flow field and oil distribution of gear in low temperature environment is still unclear. A visualized test bench for measuring the flow pattern of low temperature lubricating oil flow field is built. The transmission system component gear is simplified as rotating disk in the study. The variation rule of lubricating oil flow pattern with the disk speed at - 20 ℃ of the rotating disk are obtained. It is found that the lubricating oil flow pattern of the disk can be divided into coated, involute and reverse oil film flow pattern. The moving particle semi-implicit (MPS) numerical method can effectively simulate the flow pattern of the lubrication flow field of the disk. The mechanism of the change of oil film flow pattern of rotating disk at low temperature is revealed. The results show that the flow pattern of the oil film is greatly affected by centrifugal force. When the oil film flow pattern is involute, a clear separation point appears between the oil film and the disk. When the oil film flow pattern is reversed, the radial end face oil film of the disk disappears and there is less surface oil. It has theoretical guidance significance for the gear lubrication design under low temperature conditions, and provides a numerical calculation method of low temperature lubrication flow field.

Unsteady characteristics of lubricating oil in thrust bearing tank under different rotational speeds in pumped storage power station

Oil mist accumulation and leakage in hydropower generator bearings are common. However, they undermine not only the operational safety and stability of the generator but also the balance of living organisms downstream of rivers. Most studies on oil flow patterns are based on steady flow field simulations, which may result in potential errors particularly due to initial and unforeseen velocity increases. The unsteady multiphase flow numerical simulation method was used to calculate the motion behavior of lubricating oil in thrust bearing tanks at different rotating speeds. The variations in lubricating oil flow, pressure distribution characteristics, velocity, temperature, oil level, and vorticity at different times were obtained. The results show that the flow and pressure field distributions in an oil tank are mainly affected by the rotation of the thrust head and mirror plate and by the cooling circulation method, respectively. The lubricating oil motion becomes a function of gravity, centrifugal force, and Coriolis force. The oil surface of the volume fraction exhibited periodic motion around the tank and a climbing movement in the oil-retaining ring and oil slinger. The oil-retaining ring performs well at a speed of 500 rpm; however, minute oil droplets and mist rapidly spread in the tank due to violent oil fluctuations. Large vortices with periodic oil surfaces are also observed in regions with high turbulence intensity owing to shear and centrifugal forces. The method and framework presented can be used to optimize the structural design of thrust bearing assembly and reduce the formation of oil and gas mixtures.

Effect of Blowby on the Leakage of the Three-Piece Oil Control Ring and Subsequent Oil Transport in Upper Ring-Pack Regions in Internal Combustion Engines

The lubricating oil consumption (LOC) in internal combustion engines contributes to emission and deteriorates the performance of the aftertreatment. In this work, an optical engine with a 2D Laser-induced fluorescence (2D-LIF) system was used to study operating conditions critical to real driving oil emissions. Additionally, numerical models were used to analyze the ring dynamics, oil flow and gas flow. It was found that the intake pressure that results in zero blowby is the separation line between two drastically different oil flow patterns in the ring pack. With intake pressure lower than the separation line, the oil accumulation of the three-piece oil control ring groove (TPOCR) begins to increase, followed by the drastic increase of the oil accumulation in the third land, second land, and finally visible oil leaking through the top ring gap, given enough time. The time required for the oil to leak through different rings was investigated using both measurements and modeling. The effects of drain holes and rail gaps, as well as their relative rotation on oil accumulation and leakage from the TPOCR groove, were analyzed. These findings contribute to improving ring pack designs and engine calibration in spark ignition (SI), gas, and hydrogen engines equipped with TPOCR to minimize the negative impacts of LOC.

Research on multi-phase flow test and flow simulation test in energy enterprise automation

Abstract:In the process of oil extraction and transportation, due to the interaction between oil, gas and water, hydrates are easily generated and pipelines are blocked. Based on this, from the perspective of energy enterprise automation technology, testing and research on oil and gas multiphase flow models and flow models are carried out. The hydrate formation area is analyzed by using the hydrate formation phase equilibrium theory, and the formation rate, deposition characteristics and blockage formation mechanism are analyzed. The influence of phase flow and heat transfer; after the boundary interface coefficient between oil, gas and water is clarified, a multiphase flow model of oil, gas and water is established. In the experimental test, the differential pressure signal is used to carry out the research on the oil and gas multiphase flow model and flow model, and it is concluded that the minimum critical superficial liquid velocity among the three flow patterns of oil, water and gas is 0.113 m/s, It can clearly characterize the characteristics of the flow pattern transition, which has certain practical significance for the sustainable development of energy enterprises.

Visualization study on oil retention and flow characteristics of R32/PVE oil in suction lines with different flow orientations

Oil retention characteristic and flow patterns of R32/PVE lubricant oil mixture in compressor suction lines were investigated. Smooth copper tubes with 10.7mm inner diameter and four tube orientations including horizontal flow, vertical upward flow and inclined upward flow with 45° and 60° inclined angles, were utilized as test samples. Saturation temperature and superheat degree were maintained at 7.5°C and 12°C, respectively. The operation conditions of refrigerant mass flux and nominal oil mass fraction covered ranges of 48.5−230 kg•m−2•s−1 and 1−5%, respectively. The oil retention amount was measured by the remove and weight technique. Based on the visualization technique, flow patterns of R32/oil mixture were also observed, identified and analyzed. The characteristic of flow patterns was greatly influenced by the thermophysical properties of refrigerant-oil mixture. Comparisons of existing flow pattern maps and wet wall fraction correlations were conduct to investigate the applicability. The experimental result showed that oil retention in suction lines increased with the decrease in refrigerant mass flux and increase in oil mass fraction. The oil retention amount of 60° inclination suction line was slightly higher than that for 45°. Additionally, the difference of oil retention among the four configurations becomes limited at high mass flux conditions.

Mathematical modeling of foamy-oil flow in a cyclic solvent injection process

Foamy-oil flow is one of the main mechanisms for cold heavy oil production with sand (CHOPS) and cyclic solvent injection (CSI) processes. The flow pattern of foamy oil was observed in previous experimental studies under reasonable reservoir conditions. This study aims to investigate the foamy-oil flow mechanisms through theoretical modeling. A mathematical model is developed, which couples a solvent concentration field and a pressure field through flow velocity and oil viscosity, in which a pseudo-chemical reaction is used to describe the release of gas. The model is numerically solved by the Newton−Raphson iterative method. Results show that, firstly, during the pressure drawdown process, propane concentration decreases and oil viscosity increases with solvent exsolution in the transition zone, which restricts the bubbles coalescence and conduces to the formation of foamy oil. Secondly, the existence of bubbles leads to the buildup of local pressure gradient and causes the spatial difference of flow velocity. Moreover, when the threshold velocity is reached, the bubbles coalesce rapidly to form free gas, pushing the oil in the foamy region forward to the gas zone. Finally, the total waves of foamy-oil flow are generally 2 to 4, depending on the initial solvent concentration, oil viscosity, and pressure depletion rate. Higher initial solvent concentration, faster pressure depletion, and lighter original heavy oil lead to the easier induction of foamy-oil flow.

Experimental Study on Gas–Liquid Interface Evolution during Liquid Displaced by Gas of Mobile Pipeline

The mobile pipeline is the most effective and reliable means for the emergency oil transfer task, which is temporarily laid on the field. After completing the task, the oil in the pipeline should be emptied before the mobile pipeline is removed. The oil in pipeline gradually displaced by the air is a main method of pipeline evacuation, which is the only choice of jet fuel pipeline. Due to the convection between gas and oil phases, the length of the oil–gas mixing section and the evolution of the oil–gas interface change with time. The evolution of the gas–liquid interface directly determines the different flow patterns of oil–gas two phases, which are very important for the mobile pipeline evacuation. In this paper, the characteristics of the gas–liquid interface evolution during the water displaced by air are studied, using the multi-phase pipeline experiment. Through the change of the gas–liquid interface in the initial stage of gas cap evacuation, it is found that the gas–liquid interface can be divided into smooth, wavy, and dispersed forms under different initial gas flow rates and different inclination angles. Slug phenomenon may occur in the process of gas-carrying liquid flow in the pipeline. The emergence of slug is mainly affected by hydraulic conditions and pipeline operating conditions. The liquid plug body is complex and unstable, and there will be a mutual transition between different liquid slug shapes. The increase of the inclination angle and gas phase velocity will accelerate the occurrence of liquid slug frequency.

Gas-liquid vertical pipe flow patterns convolutional neural network classification using experimental advanced wire mesh sensor images

Flow pattern identification for simultaneous gas-liquid flow in pipes is a central problem in the petroleum industry. However, there are many conventional methods used for flow patterns identification that come with some form of restrictions limited to specific operating conditions. Although previous studies made efforts to make flow patterns identification free from biases (subjectivity), objective predictions are yet to be fully explored. For the first time, this study employs a 4-layer convolutional neural network (CNN) architecture and threshold segmentation algorithm to classify industrial working fluids of air/silicone oil flow patterns in a vertical pipe. Also, an advanced wire mesh sensor (WMS) instrumentation was used to obtain the cross-sectional frame images from a series of 52 experimental runs. This study made an attempt to use the sequential cross-sectional frames original data obtained from the experimental WMS because it is the crossing wires of the WMS that interact with the flow field and also capture the main flow pattern transitional zones. The obtained experimental testing results indicate that the supervised CNN model has an accuracy of 99.90% better than the seven-benchmarked supervised machine learning classification models used in recognizing bubbly, slug and churn flow patterns. The CNN model experimental test accuracy also outwits other related flow patterns identified in the literature when compared, thereby affirming the model's robustness. Since the WMS provide high spatial and temporal resolutions data, the average pixel intensity values from the segmented images were used as the flow indicator in identifying the transition zones within the main flow patterns. Furthermore, the Locally Interpretable Model-agnostic Explanation (LIME) algorithm for the first time was used to explain and interpret features in the WMS flow images that were contributing to the overall CNN classification scores. Finally, the CNN trained model was able to classify the main flow patterns and segmented transitional zones with certainty and confidence without subjectivity which is inherent in the direct conventional methods.

Micro-Vortex Generators on Transonic Convex-Corner Flow

A convex corner models the upper surface of a deflected flap and shock-induced boundary layer separation occurs at transonic speeds. This study uses micro-vortex generators (MVGs) for flow control. An array of MVGs (counter-rotating vane type, ramp type and co-rotating vane type) with a height of 20% of the thickness of the incoming boundary layer is installed upstream of a convex corner. The surface pressure distributions are similar regardless of the presence of MVGs. They show mild upstream expansion, a strong favorable pressure gradient near the corner’s apex and downstream compression. A corrugated surface oil flow pattern is observed in the presence of MVGs and there is an onset of compression moving downstream. The counter-rotating vane type MVGs produce a greater reduction in peak pressure fluctuations and the ramp type decreases the separation length. The presence of MVGs stabilizes the shock and shock oscillation is damped.

Flow pattern, pressure drop and inclination analysis on liquid-liquid two phase flow of waxy crude oil in pipelines using PIPESIM

Produced water is a water that comes out with the crude oil during the production of the well. It contains non-soluble and soluble oil or organics, dissolved and suspended solids with different chemicals used during production process. Thus, it must be properly accounted as it affects the economical productivity of crude oil and separation efficiency as a result of stubborn emulsions between crude oil and water. Thus, a simulation study was conducted using PIPESIM to predict the flow pattern and pressure drop of waxy crude oil and water flow in horizontal and inclined pipelines (i.e., -15° from horizontal). In this simulation study, water cuts were ranging from 0% to 90% while the flow rates were ranging from 2.03 to 16.21 cm3/s. The study comprised fluid modelling, physical modelling and running the simulation with the most suitable multiphase flow correlation in PIPESIM. This simulation study used the waxy crude oil has 16.15% of wax content and simulation was performed at 30°C. The validity of the simulation results was accomplished by comparing the published findings. There were only two types of flow patterns that can be identified by PIPESIM; stratified wavy and dispersed flow. The investigations proved that pressure drop was greatly influenced by flow rates and flow patterns. By decreasing the inclination angle, the boundary between the stratified and dispersed flow regimes shifted to the upper left of the flow pattern map while showing a higher pressure drop than horizontal pipeline due to the combined effect of pressure difference and gravity. The simulation results can be used as a platform for better understanding on more complex cases of gas, oil and water concurrent flow in pipelines.

Leading-Edge Vortex Characteristics of Low-Aspect-Ratio Sweptback Plates at Low Reynolds Number

A sweptback angle can directly regulate a leading-edge vortex on various aerodynamic devices as well as on the wings of biological flyers, but the effect of a sweptback angle has not yet been sufficiently investigated. Here, we thoroughly investigated the effect of the sweptback angle on aerodynamic characteristics of low-aspect-ratio flat plates at a Reynolds number of 2.85 × 104. Direct force/moment measurements and surface oil-flow visualizations were conducted in the wind-tunnel B at the Technical University of Munich. It was found that while the maximum lift at an aspect ratio of 2.03 remains unchanged, two other aspect ratios of 3.13 and 4.50 show a gradual increment in the maximum lift with an increasing sweptback angle. The largest leading-edge vortex contribution was found at the aspect ratio of 3.13, resulting in a superior lift production at a sufficient sweptback angle. This is similar to that of a revolving/flapping wing, where an aspect ratio around three shows a superior lift production. In the oil-flow patterns, it was observed that while the leading-edge vortices at aspect ratios of 2.03 and 3.13 fully covered the surfaces, the vortex at an aspect ratio of 4.50 only covered up the surface approximately three times the chord, similar to that of a revolving/flapping wing. Based on the pattern at the aspect ratio of 4.50, a critical length of the leading-edge vortex of a sweptback plate was measured as ~3.1 times the chord.

Flow pattern and pressure drop for oil\u2013water flows in and around 180\xb0 bends

Pressure drop and flow pattern of oil–water flows were investigated in a 19-mm ID clear polyvinyl chloride pipe consisting of U-bend with radius of curvature of 100 mm. The range for oil and water superficial velocities tested was 0.04 le U_{{{text{so}}}} le 0.950 ;{text{m/s}} and 0.13 le U_{{{text{sw}}}} le 1.10 ;{text{m/s}}, respectively. Measurements were carried out under different flow conditions in a test section that consisted of four different parts: upstream of the bend, at the bend and at two redeveloping flow locations after the bend. The result indicated that the bend had limited influence on downstream flow patterns. However, the shear forces imposed by the bend caused some shift flow pattern transition and bubble characteristics in the redeveloping flow section after the bend relative to develop flow before the bend. Generally, pressure gradient at all the test sections increased with both oil fraction and water superficial velocity and there was a sharp change of pressure gradient profile during phase inversion. The transition point where phase inversion occurred was always within the range of 0.4 le U_{{{text{sw}}}} le 0.54 ;{text{m/s}}. Pressure losses differed at the various test sections, and the difference was strongly linked to the superficial velocity of the phases and the flow pattern. At high mixture velocity, pressure losses at the redeveloping section after the bend were higher than that at the bend and that for fully developed flows. At low mixture velocity, pressure losses at the bend are higher than in the straight sections. Pressure drop generally decreased with level of flow development downstream of the bend.