Pressure Wave Attenuation Research Articles

Investigation of Backpressure Wave Propagation Properties during Gas Kicks in Managed Pressure Drilling

Summary It is often essential to provide backpressure to the wellbore by changing the opening size of the choke valve when a gas kick is detected during managed pressure drilling (MPD), which maintains the pressure in the bottom of the hole. In this study, a mathematical model was developed to explain how backpressure waves spread and weaken in a wellbore during MPD when there is a gas-liquid two-phase flow. The model is founded on a two-phase flow model, which thoroughly accounts for the gravity, shear force, and interphase interactions between the gas and liquid phases. The small perturbation theory was used to compute the backpressure wave’s propagation speed and attenuation coefficient. The outcome showed satisfactory agreement with other scholars’ experimental results. The model was used to study the impacts of the following variables on the backpressure wave propagation properties: void fraction, temperature, pressure, interphase resistance, shear force, density, invading gas composition, displacement of the drilling fluid, rate of intrusion of gas, gas-liquid surface tension, and drilling fluid viscosity. By using an example well, the laws of pressure wave propagation speed, attenuation coefficient, and propagation time with well depth were analyzed. Through evaluative methods in the field of economic management, the principal control variables governing the propagation of backpressure waves were determined. The conclusion is that, in terms of operational feasibility, lower drilling fluid density and reduced drilling fluid displacement are advantageous for a faster propagation of backpressure waves to the bottom of the well.

Analysis of train-induced aerodynamic characteristics and pressure-relief measures relating to fully enclosed noise barriers installed on railway bridges

Fully enclosed noise barriers (FENBs) are increasingly being installed on high-speed railway bridges for noise pollution control. However, the aerodynamic effects of high-speed trains passing FENBs have an adverse impact on barrier durability and generate micro-pressure waves. In this paper, a numerical model of a train passing an FENB on a bridge is established. The aerodynamic pressure distribution along the FENB is analyzed for both a single train and two trains passing one another. The propagation characteristics and evolution mechanisms of pressure waves are then investigated. The results show that the pressure is lower at the ends of the FENB and higher in the middle along the direction of train travel. The peak positive and negative pressures at the mid-span are 1.95 and 4.47 times higher than those at the ends, respectively. This distribution is caused by the propagation, superposition, reflection, and attenuation of pressure waves. Compression waves account for 78.9% of the peak positive pressure. An amplification factor must be considered when estimating the impact of two trains passing one another. Analysis of five pressure-relief schemes shows that arranging a single pressure-relief hole at a high-pressure location effectively alleviates the over-pressure in the FENB. The overall pressure-relief effect is an exponential function of the single opening area. Considering a constant opening area, arranging several relief holes at equal spacing optimizes the adverse pressure distribution compared with the single-hole relief scheme. The equivalent forces of the multi-hole scheme are 3.35% and 7.58% lower than in the single-hole scheme.

The effects of pore structure on wave dispersion and attenuation due to squirt flow: A dynamic stress-strain simulation on a simple digital pore-crack model

Squirt flow, a phenomenon typically observed in porous cracked rocks, occurs due to the contrasting compressibility between the pores and cracks, leading to the pore pressure diffusion and dissipation of wave energy. Understanding the influence of pore structure on wave dispersion and attenuation signatures due to squirt flow is essential for interpreting seismic and sonic logging data in various fields of earth and energy sciences, such as hydrocarbon exploration, geothermal energy exploitation, and CO2 sequestration. In this study, we construct a simple digital pore-crack model with varying pore structures and use a dynamic stress-strain simulation approach to characterize wave dispersion and attenuation signatures due to squirt flow. Numerical simulation suggests that, in addition to the commonly considered parameters such as porosity, crack density, and crack aspect ratio, additional pore structure parameters, such as pore size, pore aspect ratio, crack orientation, crack length, and crack width, significantly affect the wave dispersion and attenuation signatures. Increasing the pore size leads to the pronounced enhancement of attenuation magnitude and a decrease in characteristic frequency. We demonstrate that variations in crack length have a pronounced impact on attenuation magnitude, whereas crack width is decisive in controlling the characteristic frequency. Furthermore, it is found that the saturation paths (the gas filling the pore first or gas filling the crack first) considerably affect the velocity-saturation and attenuation-saturation relationship, suggesting that the coupling effects of pore structure and fluid distribution complicate the fluid pressure diffusion and wave attenuation behaviors. The presented results offer insights for deciphering pore structure parameters using attenuation- or dissipation-related seismic attributes.

Impact of Pressure Waves on Water Imbibition and Flow in Unsaturated Porous Media

AbstractThe wetting front dynamics during water imbibition in dry porous media affect the ultimate water distribution pattern. In this study, we investigate the impact of pressure pulses that emit waves in the water phase on the water distribution and imbibition patterns in porous media. We present experimental results of water spatial distribution in sand columns following infiltration under abrupt pressured‐water pulses and compare them with those of continuous inflow. Applying pressure waves during infiltration increases pressure gradients behind the wetting front, which can overcome capillary and gravitational forces, leading to uniform imbibition. To simulate the process, we developed a pore‐network model incorporating an analytical solution of pressure wave attenuation to predict the imbibition pattern. Our results demonstrate that the amplitude of the pressure wave is associated with a sharp wetting front, resulting in higher water content compared to Darcy‐type continuous flow. The findings suggest that pressure waves have the potential to achieve high water content in unsaturated media and provide insights into the spatial extent of their impact on water distribution.

Investigation of pressure wave propagation and attenuation characteristics in managed pressure drilling by fast switching throttle valve

Pressure waves possess many significant applications in the oil and gas drilling engineering field, such as mud pulse telemetry (MPT) and measurement while drilling (MWD). The focus of this research is to study the pressure wave propagation and attenuation characteristics of wellbore liquid-phase flow in managed pressure drilling (MPD) by fast switching throttle valve (FSTV). First, a mathematical model of transient pressure wave propagation along the wellbore in both upstream and downstream directions is proposed in MPD by FSTV based on the one-dimensional transient flow theory. The model considering the frictional shear effect between the pipe walls is solved by utilizing the method of characteristics. Meanwhile, boundary conditions at the drill string inlet and annulus outlet, at the throttle valve, at the junction of drill bit, and at the reducer are adequately taken into account according to the actual situation of fluid flow. Second, a laboratory experiment of excited pressure waves in a vertical wellbore is conducted to measure the variation of the pressure fluctuation with different pump rates by FSTV. Comparing with the measurement result, the calculation result is discovered that the overall change is consistent, where the maximum absolute relative error at the peak of the pressure wave is only 4.5%. Finally, it further analyzes influential factors affecting the propagation and attenuation behaviors of wellbore pressure waves in liquid-phase flow based on the model. The results indicate that pressure waveforms present sinusoidal wave propagation, and pump rates, pressure wave speed, excitation time, fluid type, mud density, fluid viscosity, and borehole size exert varying degrees of influence on downhole pressure fluctuations. The proposed model achieves accurate quantitative interpretation and analysis of downhole pressure wave in MPD by FSTV, which has important significance for the realization of safe and efficient drilling.

Water Hammer in Steel–Plastic Pipes Connected in Series

This paper experimentally and numerically investigates the water hammer phenomenon in serially connected steel and HDPE pipes with different diameters. The aim of the laboratory tests was to obtain the time history of the pressure head at the downstream end of the pipeline system. Transient tests were conducted on seven different pipeline system configurations. The experimental results show that despite the significantly smaller diameter of the HDPE pipe compared to the steel pipe, introducing an HDPE section makes it possible to suppress the valve-induced pressure surge. By referring to the results of the experimental tests conducted, the comparative numerical calculations were performed using the fixed-grid method of characteristics. To reproduce pressure wave attenuation in a steel pipe, Brunone-Vitkovský instant acceleration-based model of unsteady friction was used. To include the viscoelastic behavior of the HDPE pipe wall, the one-element Kelvin–Voigt model was applied. By calibrating the unsteady friction coefficient and creep parameters, satisfactory agreement between the calculated and observed data was obtained. The calibrated values of parameters for a single experimental test were introduced in a numerical model to simulate the remaining water hammer runs. It was demonstrated that using the same unsteady friction coefficient and creep parameters in slightly different configurations of pipe lengths can be effective. However, this approach fails to reliably reproduce the pressure oscillations in pipeline systems with sections of significantly different lengths.

Comparison of frequency domain and time domain methods for the numerical simulation of contactless ultrasonic cavitation

The use of a top-mounted electromagnetic induction coil has been demonstrated as a contactless alternative to traditional ultrasonic treatment (UST) techniques that use an immersed mechanical sonotrode for the treatment of metals in the liquid state. This method offers similar benefits to existing UST approaches, including degassing, grain refinement, and dispersion of nanoparticles, while also preventing contact contamination due to erosion of the sonotrode. Contactless treatment potentially extends UST to high temperature or reactive melts. Generally, the method relies on acoustic resonance to reach pressure levels suitable for inertial cavitation and as a result the active cavitation volume tends to lie deep in the melt rather than in the small volume surrounding the immersed sonotrode probe. Consequently, (i) with suitable tuning of the coil supply frequency for resonance, the treatment volume can be made arbitrarily large, (ii) the problem of shielding and pressure wave attenuation suffered by the immersed sonotrode is avoided. However, relying on acoustic resonance presents problems: (i) the emergence of bubbles alters the speed of sound, resonance is momentarily lost, and cavitation becomes intermittent, (ii) as sound waves travel through and reflect on all the materials surrounding the melt, the sound characteristics of the crucible and supporting structures need to be carefully considered. The physics of cavitation coupled with this intermittent behaviour poses a challenge to sonotrode modelling orthodoxy, a problem we are trying to address in this publication. Two alternative approaches will be discussed, one of which is in the time domain and one in the frequency domain, which couple the solution of a bubble dynamics solver with that of an acoustics solver, to give an accurate prediction of the acoustic pressure generated by the induction coil. The time domain solver uses a novel algorithm to improve simulation time, by detecting an imminent bubble collapse and prescribing its subsequent behaviour, rather than directly solving a region that would normally require extremely small time steps. This way, it is shown to predict intermittent cavitation. The frequency domain solver for the first time couples the nonlinear Helmholtz model used for studying cavitation, with a background source term for the contribution of Lorentz forces. It predicts comparable RMS pressures to the time domain solver, but not the intermittent behaviour due to the underlying harmonic assumption. As further validation, the frequency domain method is also used to compare the generated acoustic pressure with that of traditional UST using a mechanical sonotrode.

Study on the propagation characteristics of pressure wave generated by mechanical shock in leaking pipelines

This paper focuses on the characteristics of pressure wave generated by an active mechanical shock in leaking pipelines. A piston type pressure wave generator was designed and applied to the pipeline experimental system and a three-dimensional (3D) numerical simulation model was developed based on the k-ε turbulence model and dynamic mesh. The experimental results showed that the maximum amplitude of pressure wave was about 104.71 kPa, and the leakage intensified the attenuation of pressure wave in space and time through quantitative analysis. Based on the 3D simulations, the processes of the pressure wave generation and propagation were revealed. The amplitude of pressure wave increased linearly with the increase of the maximum velocity of mechanical shock, and the effects of leakage on the waveforms of pressure wave were observed under the dimensionless analysis. In addition, a shorter duration of mechanical shock can increase the amplitude of the pressure wave generated. The results presented in this paper will contribute to the development and application of the transient leak detection method for pipeline systems.

Impact of fluid viscoelasticity on the pressure wave in laminar fluid hammer in helical tubes-an experimental study

The fluid hammer phenomenon can cause severe damages to the hydraulic systems. As its potential exists in systems with viscoelastic fluids as the working fluid, investigating the impact of viscoelasticity on this phenomenon has been the primary target of this study. The built experimental setup includes copper and low-density polyethylene tubes, and dilute polyacrylamide solutions are implemented as the viscoelastic fluid. Results indicated that the viscoelasticity signifies the pressure wave attenuation. The pressure wave damping rate was 14.67% more considerable in the 400 ppm solution than water. Increasing the Deborah number by 41.59% in copper tube, and 38.72% in polyethylene tube led to 21.05 and 3.96% rise in the wave rate of attenuation, respectively. The same growth in Deborah number has caused a descending trend in the acoustic wave speed relative to water, by 0.88% decrease in the copper and 2.90% decrease in the polyethylene tube. Also, despite the results with water in the copper tube, the time distance of subsequent peaks was unequal in tests with viscoelastic fluids.

Study the response of materials under high pressure loading

Materials which can absorb the high energy flow are of great importance. The high pressure waves, generated by an explosion or high impact loading, have a very high energy value and it causes a great damage to the objects which come in its path. Though every material, depending upon its properties, offers certain degree of resistance to the flow of energy, there are some materials which have the ability to absorb much more energy than others. These materials when combined together or when layered with other materials, can act as an entity which if suitably formed and placed, can resist the flow of high energy in a very effective manner. The research in the field of developing new materials and composites, is evolving as one of the promising research area in the field of material science as they can do wonders in saving precious lives and properties from the damaging effects of high pressure waves. In this paper the concept is presented by employing the high energy absorbing materials and their combinations (i.e. layered together), to study their effectiveness against the impact of high pressure waves produced by an explosion of TNT charge kept at a certain distance. Conditions have been simulated using ANSYS Autodyn software. Attenuation of high pressure waves is observed by studying the Energy absorption property of the materials as a key parameter. The deformation of the material plate and other associated parameters are also studied.

Downhole gas-kick transient simulation and detection with downhole dual-measurement points in water-based drilling fluid

Gas kick is generally difficult to discover in time using traditional surface detection methods, which results in a significant wastage of time and money. Owing to the restriction of the low data-transmission speed of measurement-while-drilling system, downhole measured data is usually ignored in gas-kick detection. Furthermore, surface detection methods comprising the use of pressure and flow-rate sensors require professional knowledge and many input parameters, some of which are required to be assumed. In this study, we used downhole dual measurement points for detecting gas kick without the use of other surface input parameters. Firstly, we developed an end-to-end supervised neural network to determine the still and circulation working conditions, which were used for calculating the drilling fluid density and viscosity. Secondly, an unscented Kalman filter was applied to perform a backward gas fraction calculation dynamically. However, this downhole calculation method cannot be used in highly deviated and horizontal wells. Because there is a downhole fluctuating pressure generated during the rock breaking, we proposed an auxiliary gas-kick detection method based on the theory of pressure wave attenuation. This method can be applied to all well types. To evaluate the proposed gas-kick detection method, we used a gas-liquid flow simulation model combined with a pump rate model, screw-drilling-tool pressure-consumption model, rock-breaking model, and formation permeability model to generate transient data with the highest possible accuracy. The advection upstream splitting model was used as the numerical scheme. The accuracy of the simulation model was successfully validated using two field experimental data sets. Finally, we generated a set of vertical and horizontal well data each with the simulation model to test the gas-kick detection method. The experiment results showed that the proposed gas-kick detection model was successful in detecting gas kick and obtaining the accurate gas fraction.

Study on pressure wave propagation through cryogenic condensing two-phase flow in liquid rocket propellant feedline

This paper presents a numerical study on the pressure wave traveling in the condensing flow of the liquid and vapor oxygen in the tank-to-engine propellant feedline of liquid rocket. A computational fluid dynamics (CFD) model is developed based on Eulerian multiphase model, and the coupling of pressure wave and flow condensation is achieved through incorporating user-defined functions (UDF) with interphase mass, heat and momentum exchange models. Experimental validation is undertaken and the predicted pressure profiles by CFD simulation prove to be in good agreement with experimental data. The simulation results indicate that the distance required to condense the oxygen mixture to pure liquid fluctuates with propagation of the pressure wave which experiences attenuation and deceleration with a speed of the order of 1–14 m/s. As the local vapor content reduces, the pressure wave speed increases in an exponential way with an abrupt increase greater than an order of magnitude taking place on transition to the single-phase liquid oxygen, while the amplitude attenuation decreases linearly. The dependence of pressure wave speed and attenuation on frequency satisfy exponential and logarithmic relations, respectively. The wave speed is to a large extent independent of the high frequencies and exhibits a dispersed characteristic at low frequencies.

Transient Pressure Fluctuation Effect During Gas Drilling in Horizontal Well

Combining gas drilling technology with horizontal well drilling leads to improvement in production in oil and gas reservoirs. However, wellbore gas encountering high-pressure formation gas could bring substantial risks in gas drilling process. A theoretical model for pressure wave speed and attenuation coefficient in gaseous phase flow is established and analytically solved by classic fluid-mechanics model and small perturbation theory. The simulation results suggest that the main factors affecting the pressure wave are angular frequency, pipe diameter, and original pressure. In addition, a pressure wave test device is designed to validate the model, and the experimental results fit well with the simulation results. The work presented in this paper can provide a theoretical basis for horizontal section gas drilling and can also detect gas influx to ensure safety and prevent accidents.

Leakage Localization for Long Distance Pipeline Based on Compressive Sensing

Leakage in the long distance pipelines may lead to severe impairment to water transportation. In practice, dealing with the data collected by wireless sensor networks (WSNs) is essential to achieve real-time leakage localization to reduce water loss. More sensors may improve the effectiveness of monitoring the leakage of long distance pipelines. However, to avoid deploying numerous sensors which leads to drill many holes in the pipeline to install them, a novel algorithm based on the compressive sensing (CS) theory is proposed in this paper. First, a new sensing matrix named pressure variation decay (PVD) model based on the attenuation of pressure wave is creatively established, which describes the leakage status of long distance pipeline concretely. As such, the equation of leakage localization based on CS theory reconstruction algorithm is deduced. Then, in order to assess this new method, the simulation of the method and the discussion of results are conducted. Finally, the results show that the proposed algorithm possesses validness and excellent robustness, even if the interference of noise.

A novel location algorithm for pipeline leakage based on the attenuation of negative pressure wave

Numerous types of liquid, such as water, oil, and so on, are transported via pipelines. Thus, leakage in the pipelines can cause severe hazards to liquid transportation and pose great risks to industries, environment and dwellers. For the purpose of an accurate identification of the leakage location, a novel location algorithm is proposed in this paper based on the attenuation of negative pressure wave (ANPW). As such, this paper presents some of the first efforts in the investigation of the relationship between the pressure difference and leakage location. This is in direct contrast with the traditional method, which relies on the use of the time difference and the velocity of NPW for leakage detection and location. Accordingly, the ANPW method avoids the potential problems of the traditional NPW method – the difficulty for pinpointing the time difference and the disturbance of the velocity of NPW by the liquid flow rate in the pipeline. To explore this new method, this paper firstly deduces the propagation equation of NPW along with the pipeline using the momentum equation and the continuity equation. This is followed by proposing that the ANPW method depends on the change of pressure in place of the time difference. Thirdly, a test of the method in the actual pipeline and comparison between the ANPW method and the time difference method are conducted. Yielding the largest error of 1.161% and the smallest error of 0.355%, the experiment leads to the conclusion that the new method can be applied to the location of pipeline leakage.

Research on Hydraulic Characteristics in Diversion Pipelines under a Load Rejection Process of a PSH Station

Transient analysis in diversion pipelines should be performed to ensure the safety of a hydropower system. After the establishment of a three-dimensional (3D) geometric model from the part upstream reservoir to the diversion pipeline end in a pumped storage hydropower (PSH) station, the hydraulic characteristics of the diversion system were solved by Reynold average Navier–Stokes (RANS) equations based on a volume of fluid (VOF) method under the condition of simultaneous load rejection of two units. The variations of the water level in the surge tank, the pressure at the pipeline end, and the velocity on the different pipeline sections with time were obtained through the calculation. The numerical results showed that the water level changing in the surge tank simulated by VOF was consistent with the field test data. These results also showed that a self-excited spiral flow occurs in the pipeline when the flow at the end of the pipeline was reduced to zero and its intensity decreased with the flow energy exhaustion. The discovery of the self-excited spiral flow in the study may provide a new explanation for the pressure wave attenuation mechanism.

Modeling of Wave Propagation in Drilling Fluid

The study presents a one-dimensional (1D) numerical model of wave propagation as well as transmission/reflection phenomena in Newtonian and non-Newtonian drilling mud flow associated with oil/gas drilling activities. Propagation of wave formed due to back pressure changes by means of a choke is investigated. In general, the reflection and transmission of pressure waves at intersection of conduits with different cross sections or in case of partial blockage typical of drilling practices is multidimensional and caused by nonuniform boundary conditions over the cross section. The 1D approach is investigated to approximate the multidimensional reflection and transmission of pressure pulse at areal discontinuity in conduit. The approach is facilitated by introduction of a local force exerted by solid wall on the fluid at the intersection of the conduits into conservative form of the equation for momentum conservation. In addition, nonconservative formulation of momentum equation was explored. To solve the differential equations, MacCormack numerical scheme with second-order accuracy is applied to the nonlinear Euler and 1D viscous conservation equations. A grid refinement study is performed. It is shown that nonconservative form of the conservation laws results in more accurate prediction of transmission and reflection in case of areal discontinuity. The results of the numerical modeling are presented in terms of pressure wave propagation and attenuation upon reflection and transmission at consequent interfaces.

Pressure wave attenuation in agas solid fluidized bed: Effects of particles size, density and the electrostatic charge

Simultaneously digital image analysis (DIA) and pressure fluctuation analysis (PFA) have been employed to study the pressure wave attenuation behavior in a gas-solid fluidized bed. The effects of particles size, density, and natural electrostatic charge have been investigated. It was shown that increasing of the particle density leads to an increase in the pressure amplitude but has no effect on the pressure wave attenuation trend. It was also observed that the maximum pressure amplitude is proportional to the mass loaded in the bed above the probe. Increasing the particle size and having electrostatic charge both lead to an increase in the local void fraction of the dense phase which in turn lead to a reduction in the pressure amplitude and increasing the pressure wave decay factor. Thus, the wave attenuation trend can be attributed to the local void fraction of particles in the emulsion phase.

Experimental Study on Acoustic Attenuation Due to Solid Particles

ABSTRACTHigh-frequency pressure waves present in rocket motors can be dampened by solid or liquid particles produced from their propellant combustion depending on conditions. The present study conducted an experimental investigation into the effects of particle sizes, ambient gases, and pressure wave frequencies on the attenuation of acoustic energy. Aluminum oxide powders of single-peak broad distributions with average diameters of 5.1 μm, 7.6 μm, 16.5 μm, and 36.2 μm were used to simulate condensed particles in solid rocket combustion environment. Attenuation of excited pressure waves traveling through the fixed cylindrical volume full of particle-laden helium or nitrogen gas has been measured. The number densities of particles floating in gases have been determined by use of processing of images from a high-speed camera. It is observed that alumina particles surely have attenuation effects of pressure waves. The particles in helium show approximately two times greater pressure wave attenuation than those in nitrogen, which indicates the effect of gas density on the attenuation of pressure wave by particles. The optimal particle diameter for the maximal attenuation varies with the frequency of pressure wave. Pressure wave attenuation reaches maximal values at an average particle diameter of 7.6 μm in helium and 16.5 μm in nitrogen over frequencies. Particle diameters showing maximal attenuation become shifted and so do the attenuation characteristics for both cases of helium and nitrogen for high frequency waves greater than 2500 Hz.

Experimental study on the pressure wave attenuation across gas-solid fluidized bed by single bubble injection

In this paper attenuation of the pressure wave has been studied for understanding the nature of pressure wave propagation in a gas-solid fluidized bed. The important aspect of the present work is to obtain more insights about the trend of the attenuation of the pressure wave induced by bubble injection in a fluidized bed in the whole of the bed and in the spatial intervals. Experimental results show that the attenuation of the pressure wave decreases as the diameter of bubble increases. To capture the pressure wave attenuation in the fluidized bed, it is proposed to install the pressure probe in positions approximately higher than AR times of the bubble diameter, where AR is the bubble height to width ratio. Moreover, it has been found that the attenuation in upper levels of the bed is greater than that of the lower levels of the bed. The pressure wave attenuation studies confirm that the dense phase around a bubble in the fluidized bed cannot be considered as a homogeneous phase with the same solid volume fraction.