Fluid Pressure Waves Research Articles

Research on the impact of overflow well shut-in on wellbore integrity and safety

If an overflow occurs, the well must be closed immediately. To ensure the safety of the drilling wellbore in ultra-deep wells, it is critical to analyze the transient flow process and pressure fluctuations of the fluid in the annular space of the overflow well shut-in. This paper investigates the pressure fluctuation model of multi-phase fluid in the annular space after overflow occurs during gas well drilling, analyzes the influence factors of multi-phase fluid's pressure wave velocity, and simulates and analyses pressure fluctuation changes in the annular space in light of the impact of overflow well shut-in on wellbore safety. The model's correctness is verified by comparing it to experimental data published in the literature. The model is developed and examined using the example of a genuine gas well in western China. According to the study, as soon as the BOP closes, pressure rapidly increases to a high of 6.09 MPa at 5.89 s before falling to a valley of 4.68 MPa at 35.36 s. When the mild shut-in time lasts 20 s, the wellhead annular pressure reaches a maximum of 5.8 MPa. If the wellhead equipment can withstand the annular space's first pressure wave, a hard shut-in is recommended. To optimize the overflow well shut-in system and ensure wellbore safety, the change in pressure in the wellhead annular space as a result of varied shut-in timings and drilling fluid displacement is studied.

Epidural pressure measurement using a fiber-optic sensor (proof-of-principle invivo animal trial).

An increase in epidural pressure around the stenosis has been observed in patients with lumbar spinal stenosis (LSS) with positive signs of sedimentation or redundant nerve roots. Further analysis of the pressure conditions in the stenotic area would be of great interest. We hypothesized that it would be possible to determine the physiological parameters of the epidural pulse wave and its course in pathological stenosis as a basis for objective identification of LSS based on pressure using a new measuring method with continuous spatial and temporal resolution. We performed a single-case proof-of-principle invivo animal trial and used a newly developed hybrid pressure-measurement probe with a fiber-tip Fabry-Pérot interferometer and several fiber Bragg gratings (FBG). With reproducible precision, we determined the mean epidural pressure to be 7.5 mmHg and the peak-to-peak value to be 4-5 mmHg. When analyzing the pressure measured by an FBG array, both the heart and respiratory rates can be precisely determined. This study was the first to measure the pulse wave velocity of the cerebrospinal fluid pressure wave as 0.97 m/s using the newly developed pressure probe. A simulated LSS was detected in real time and located exactly. The developed fiber-optic pressure sensor probe enables a new objective measurement of epidural pressure. We confirmed our hypothesis that physiological parameters of the epidural pulse wave can be determined and that it is possible to identify an LSS.

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.

On the reduction of the flow-induced noise using porous material plates with high acoustic transmissibility

This study investigates the efficacy of closed-structure porous materials for reducing flow-induced noise, given their high acoustic transmissibility and low fluid permeability. A multifaceted approach encompassing wind tunnel experiments, numerical simulations, and practical applications to heating, ventilation, and air-conditioning (HVAC) systems in commercial electric vehicles was adopted. Wind tunnel experiments demonstrated a significant reduction, over 20 dB, in the tonal noise generated from a rectangular cylinder and an increase in its frequency, attributable to changes in the vortex structure and velocity fluctuations in the wake of the cylinder. The numerical simulation of fluid permeation and pressure wave conditions on the surface of the porous material as a boundary condition aligned with the experimental outcomes, suggesting that such permeation conditions could lead to noise and drag reduction. Practical testing showed a 5 dB noise reduction at the driver's ear position when porous materials were attached to a portion of an electric vehicle's HVAC system. The noise reduction was associated with changes in velocity fluctuations in the flow field, aligning with the wind tunnel experimental findings. This study provides promising insights into the development of effective noise reduction strategies using porous materials.

Application of a novel PhysioCell apparatus for biopredictive dissolution tests of oral immediate release formulations – A case study workflow for in vitro-in vivo predictions

Biorelevant dissolution tests of oral solid dosage forms open the gate to valid in vitro-in vivo predictions (IVIVP). A recently developed apparatus, PhysioCell, allows mimicking the fluid flow and pressure waves occurring in the human fasted stomach. In this work, we used the PhysioCell to perform IVIVP for vortioxetine immediate-release (IR) tablets: the originator (Brintellix) and generic product candidates (VORTIO). The dissolved drug was monitored in the gastric (StressCell) and intestinal (Collection Vessel) compartments that contained biorelevant media. Simulated intermittent gastric stress at 15 min and “housekeeping wave” at 30 min increased the dissolution of Brintellix formulations only. A mechanistic model that best described the observations involved the first-order tablet disintegration with a stress-induced enhancement for Brintellix, dissolution of solid particles in the StressCell, and drug transfer to the Collection Vessel. Then, a semi-mechanistic pharmacokinetic model with dissolution parameters as inputs simulated vortioxetine plasma concentrations in healthy volunteers after single and multiple dosing of Brintellix. Despite different dissolution characteristics, VORTIO provided similar concentration profiles to the originator. In conclusion, PhysioCell dissolution tests, combined with semi-mechanistic IVIVP, can be successfully used to develop IR dosage forms exhibiting gastric stress-related effects.

Comparison of Fluid Pressure Wave between Biot Theory and Storativity Equation

Compressibilities of pore fluid and rock skeleton affect pressure profile and flow velocity of fluid in aquifers. Storativity equation is often used to characterize such effects. The equation suffers from a disadvantage that at infinite large frequency, the predicted velocity of fluid pressure wave is infinitely large, which is unrealistic because any physical processes need certain amounts of time. In this paper, Biot theory is employed to investigate the problem. It is shown that the key equations of Biot theory can be simplified to storativity equation, based on low-frequency assumption. Using Berea sandstone as an example, we compare phase velocity and the quality factor between Biot theory and storativity equation. The results reveal that Biot theory is more accurate in yielding a bounded wave velocity. At frequency lower than 100 kHz, Biot theory yields a wave velocity 8 percent higher than storativity equation does. Apparent permeability measured by fluid pressure wave (such as Oscillatory Hydraulic Tomography) may be 14 percent higher than real permeability measured by steady flow experiments. If skeleton is rigid, Biot theory at very high frequencies or with very high permeabilities will yield the same velocity as sound wave in pure water. The findings help us for better understanding of the physical processes of pore fluid and the limitations of storativity equation.

Analysis of the 15 December 2017 Mw 6.5 and the 23 January 2018 Mw 5.9 Java Earthquakes

ABSTRACT The west part of Java sits at the transition from oblique subduction of the Australian plate under the Sunda block of the Eurasian plate along Sumatra to orthogonal convergence along central and eastern Java. This region has experienced several destructive earthquakes, the 17 July 2006 Mw 7.7 earthquake and tsunami off the coast of Pangandaran and the 2 September 2009 Mw 7 earthquake, located off the coast of Tasikmalaya. More recently, on 15 December 2017, an Mw 6.5 earthquake occurred off the coast near Pangandaran, and, on 23 January 2018, an Mw 5.9 earthquake occurred offshore Lebak, between Pelabuhan Ratu and Ujung Kulon. Ground shaking and damage occurred locally and in Jakarta on the northern coast of Java. In this study, we use the double-difference technique to relocate both mainshocks and 10 months of seismicity (228 events) following the earthquakes. The relocation result improved the mainshock locations and depth distribution of earthquakes. Moment tensor of the December 2017 event located the hypocenter at ∼108 km depth within the subducting slab. The best-fit relocation places the depth at 61 km, close to the slab interface. Aftershocks occur between 68 and 86 km depth and align along a steeper plane than slab geometry models. The January 2018 event is located at ∼46 km depth. Aftershocks form a near-vertical, pipe-like structure from the plate interface to ∼10 km depth. A burst of aftershocks immediately following the mainshock shows a shallowing upward trend at a rate of ∼2 km/hr, suggesting that a fluid pressure wave released from the oceanic crust is causing brittle failure in the overriding plate, followed by upward migration of fluids. Five months later, shallow (<25 km) seismicity collocates with background seismicity, suggesting the January 2018 event activated the Pelabuhan Ratu fault system close to the coast.

Hearing at threshold intensities: by slow mechanical traveling waves or by fast cochlear fluid pressure waves.

The three modes of auditory stimulation (air, bone and soft tissue conduction) at threshold intensities are thought to share a common excitation mechanism: the stimuli induce passive displacements of the basilar membrane propagating from the base to the apex (slow mechanical traveling wave), which activate the outer hair cells, producing active displacements, which sum with the passive displacements. However, theoretical analyses and modeling of cochlear mechanics provide indications that the slow mechanical basilar membrane traveling wave may not be able to excite the cochlea at threshold intensities with the frequency discrimination observed. These analyses are complemented by several independent lines of research results supporting the notion that cochlear excitation at threshold may not involve a passive traveling wave, and the fast cochlear fluid pressures may directly activate the outer hair cells: opening of the sealed inner ear in patients undergoing cochlear implantation is not accompanied by threshold elevations to low frequency stimulation which would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. The magnitude of the passive displacements at threshold is negligible. Isolated outer hair cells in fluid display tuned mechanical motility to fluid pressures which likely act on stretch sensitive ion channels in the walls of the cells. Vibrations delivered to soft tissue body sites elicit hearing. Thus, based on theoretical and experimental evidence, the common mechanism eliciting hearing during threshold stimulation by air, bone and soft tissue conduction may involve the fast-cochlear fluid pressures which directly activate the outer hair cells.

Non-Destructive Evaluation Device for Monitoring Fluid Viscosity.

There is an increasing need for non-destructive, low-cost devices for real-time fluid viscosity monitoring. Therefore, in this study, a method based on structural health monitoring is adapted for monitoring fluid properties. A device is built such that an inexpensive and disposable viscosity probe be possible. The design incorporates a sensor/actuator pair using a piezoelectric material layered with copper/brass and capable of monitoring viscosity changes in low volume liquids (e.g., vacutainer vial). Experiments performed with the new device show a definite pattern of wave propagation in viscous solutions. A numerical model is built to investigate the wave propagation in the fluid. For experimental measurements, the sensor part of the device detects the generated pressure wave in fluid (e.g., air, water, glycerin) by the actuator part. The phase shift between the actuator and the sensor signals is then recorded and plotted for different concentrations of glycerin and water at room temperature. The results of this study show a direct correlation between the phase shift and varying viscosity in the ultrasonic frequency range from 6 to 9 MHz. The numerical simulation, performed utilizing acoustic modal and harmonic response analysis, results also demonstrate the same trend as the experimental results: a phase shift increases with the viscosity of the fluid.

Labyrinthine concussion: Historic otopathologic antecedents of a challenging diagnosis.

ObjectiveThe term “labyrinthine concussion” has evolved to mean audiovestibular dysfunction in the absence of a temporal bone fracture (TBF). Despite a multitude of case descriptions of labyrinthine concussion, the precise pathophysiology remains poorly understood. Herein, we explore the historical otopathologic underpinnings of the diagnosis of labyrinthine concussion with a focus on the auditory pathway during the late 19th to the mid‐20th centuries and conclude with a discussion of its contemporary relevance.Methods and Data SourcesA review of primary and secondary medical sources written in English, German, and French on otopathology labyrinthine concussion studies from the late‐19th to the mid‐20th centuries.ResultsAround the turn of the 20th century, otopathologists identified histologic changes in the temporal bones of individuals that sustained head injury without TBFs. Based on these otopathologic findings in humans, early experiments investigating the pathophysiology of labyrinthine concussion were performed in animals through either the delivery of blows to the head or direct introduction of a pressure wave into the labyrinthine fluid. Collectively, otopathologists hypothesized that predominant mechanisms for labyrinthine concussion included inner ear hemorrhage, cochleovestibular nerve traction injury, direct damage from a labyrinthine fluid pressure wave, or vasomotor dysfunction.ConclusionHistorical study shows a variety of inner ear pathologies potentially responsible for auditory dysfunction following head injury. Understanding the history and otopathology of labyrinthine concussion may help clinicians focus on new pathways toward novel research and improved patient care.

Multi-field coupling dynamic response analysis of pipelines with double corrosion defects under seismic loading in cold regions

Multi-field coupling system in the paper is composed of the corroded pipelines, fluid, heat preservation layers and frost -heaving soil, and the buried pipelines are inevitable to be affected by earthquakes, but few studies have been done on corroded pipelines in multi-field coupling under seismic loading in cold regions. The paper analyzes the dynamic response of the pipelines under seismic loading. Method by FEM (finite element method), the three-dimensional multi-field coupling mechanics model has been established for analysis, based on a thermal-fluid-solid multi-field coupling analysis theory, considering the actual stress-strain characteristics of the pipeline steel and the frost heaving force of soil. Meanwhile, the influences of fluid pressure, fluid temperature, corrosion defects and seismic waves on the mechanical properties of the pipelines are then discussed. The results show that: the relative corrosion depth, fluid pressure and fluid temperature have obvious influence on the mechanical properties of corroded pipelines; other factors are relatively weak; the properties of corroded pipelines do not change with different seismic loading. For the corroded pipelines in cold regions, the factors which have obvious influence on the mechanical properties of pipelines should be monitored intensely.

Lateral Semicircular Canal Pressures During Cochlear Implant Electrode Insertion: a Possible Mechanism for Postoperative Vestibular Loss.

Insertion of cochlear implant electrodes generates transient pressure spikes within the vestibular labyrinth equivalent to high-intensity acoustic stimuli. Though cochlear implant (CI) surgery is regarded as having low risk of impacting the vestibular system, several studies have documented changes in vestibular function after implantation. The mechanism of these changes is not understood. We have previously established that large, potentially damaging pressure transients can be generated in the cochlea during electrode insertion, but whether pressure transients occur within the vestibular labyrinth has yet to be determined. Here, we quantify the exposure of the vestibular system to potentially damaging pressure transients during CI surgery. Five human cadaveric heads were prepared with an extended facial recess and implanted sequentially with eight different CI electrode styles via a round window approach. Fiber-optic sensors measured intralabyrinthine pressures in scala vestibuli, scala tympani, and the lateral semicircular canal during insertions. Electrode insertion produced a range of high-intensity pressure spikes simultaneously in the cochlea and lateral semicircular canal with all electrodes tested. Pressure transients recorded were found to be significantly higher in the vestibular labyrinth than the cochlea and occurred at peak levels known to cause acoustic trauma. Insertion of CI electrodes can produce transients in intralabyrinthine fluid pressure levels equivalent to high-intensity, impulsive acoustic stimuli. Results from this investigation affirm the importance of atraumatic surgical techniques and suggest that in addition to the cochlea, the vestibular system is potentially exposed to damaging fluid pressure waves during cochlear implantation.

Vibration of the Basilar Membrane and Fluid Pressure Distribution in the Human Cochlea

AbstractThe human inner ear or cochlea is a bone structure of spiral shape and is composed of mainly two conical chambers which are filled with fluid and separated by a soft membrane, referred to as the basilar membrane. At the apical end, both chambers are connected through a small opening, the helicotrema. At the base, the chambers are closed by the stapes footplate and the round window membrane. In case of a normal ear, sound is received by the eardrum, transmitted through the middle ear ossicles and finally excites the inner ear fluid through the vibration of the stapes footplate. According to present hearing theory, this leads to pressure waves in the cochlear fluid which in turn results in characteristic vibration behavior of the basilar membrane. Related to the sound frequency, hair cells in certain areas of the basilar membrane are stimulated and cause hearing nerve stimulation. In order to predict the effect of inner ear diseases on hearing impression as well as to develop new hearing implants, a deeper understanding of the cochlear dynamics is needed. However, since the cochlea represents a closed hydraulic system with a complex geometry, the motion of the basilar membrane as well as the fluid pressure can hardly be measured. Therefore, a numerical model of the uncoiled cochlea is developed representing the fundamental physical effects occurring in the cochlea. Taking the fluid‐structure interactions into account, the transfer behavior of the cochlear system is investigated for different excitation frequencies within the auditory frequency range of humans. The simulations show the passive vibration of the basilar membrane resulting in the characteristic traveling wave. These results allow to study the mapping of the excitation frequency to its characteristic pattern along the basilar membrane, called tonotopy. Further, the spatial fluid pressure distribution along the cochlear chambers is evaluated and allows new insights into the cochlear physics. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Pore Fluid Extraction by Reactive Solitary Waves in 3‐D

AbstractIn the lower crust, viscous compaction is known to produce solitary porosity and fluid pressure waves. Metamorphic (de)volatilization reactions can also induce porosity changes in response to the propagating fluid pressure anomalies. Here we present results from high‐resolution simulations using Graphic Processing Unit parallel processing with a model that includes both viscous (de)compaction and reaction‐induced porosity changes. Reactive porosity waves propagate in a manner similar to viscous porosity waves, but through a different mechanism involving fluid release and trap in the solid by reaction. These waves self‐generate from red noise or an ellipsoidal porosity anomaly with the same characteristic size and abandon their source region to propagate at constant velocity. Two waves traveling at different velocities pass through each other in a soliton‐like fashion. Reactive porosity waves thus provide an additional mechanism for fluid extraction at shallow depths with implications for ore formation, diagenesis, metamorphic veins formation, and fluid extraction from subduction zones.

A new model describing the interaction between fluid pressure wave in pores and P-wave in rock matrix

The interaction between seismic waves in rocks and fluid pressure in pores remains one of the most challenging topics in seismic exploration. A perturbation technique is used to develop a new model to describe the propagation of fluid pressure in pores associated with P-waves in the rock matrix. The basic idea is to approximate classification of waves in saturated rocks into two orders. The first order is a dominant P-wave in the matrix, and the second order is a companion fluid wave induced by the first-order wave. This approach is innovative and advantageous in that the complex interactions of stress between the matrix and fluid are decoupled and the mathematical solutions become easy to seek for. The fluid pressure wave is analyzed by a 1D plane wave ignoring the Poisson’s effect. Parameterization of the model using sandstone saturated with water results in the conclusion that the fluid wave has an amplitude one order of magnitude smaller than the matrix wave and the two waves have a very slight phase difference. We have also evaluated the potential application of our model to shale gas and shale oil.

Computation of acoustic wave responses due to moving underwater acoustic sources in complex underwater environments using a spectral element method

This work presents a new numerical approach for computing underwater acoustic wave responses due to moving underwater acoustic sources in complex underwater environments using a Spectral Element Method (SEM). The SEM is similar to the Finite Element Method (FEM), but uses a higher-order shape function with Gauss-Lobatto-Legendre quadrature, naturally creating a diagonal mass matrix. Thus, we can use fast explicit time integration, taking advantage of a diagonal mass matrix, without compromising accuracy. Therefore, the SEM is much more suitable for large-scale parallel 3D time domain wave analyses than the conventional FEM. In our numerical experiments, we used a large-scale parallel SEM wave simulator, SPECFEM3D. We verified the SEM solution of acoustic (fluid pressure) waves in a 3D acoustic fluid setting of an infinite extent, induced by a moving point source, by using its analytical counterpart. Numerical experiments showed that our tool accurately accommodates wave behavior at fluid-solid interfaces of complex geometries and infinite extents of water and solids, truncated using absorbing boundary conditions. Due to such versatility, our tool can be used for forward and inverse acoustic wave analyses in any complex underwater systems of large extents (e.g., shallow water and deep ocean).

Protection of pipeline bridges against vibrations caused by a water hammer

In pipeline systems, bridges are much more exposed to exceptional loadings and related failures than other elements of hydraulic plants. Water hammer, a phenomenon of abrupt change in fluid pressure caused by e.g. the sudden closing or opening of a valve, pump failure or a power cut, is an example of such loading. The reasons for this phenomenon and the possible failure it can cause are discussed in the article. An overview of the currently used protection methods against a water hammer and the possibilities to improve the construction of the devices that are used for such protection are shown. The effectiveness of three selected systems of protecting against a water hammer is discussed in detail. It is underlined that in the case of large-span pipeline bridges, especially suspension bridges, natural frequencies of the bridge can coincide with the frequency of the fluid pressure wave caused by a water hammer. This resonance can cause excitation of pipeline bridge vibrations. The possibilities of eliminating pipeline vibrations by applying vibration absorbers or flexible supports are pointed out. The importance of the need of detailed structural dynamic analysis and the determination of eigenfrequencies with their corresponding eigenforms is highlighted.

Bayesian inversion of pressure diffusivity from microseismicity

We have considered the problem of using microseismic data to characterize the flow of injected fluid during hydraulic fracturing. We have developed a simple probabilistic physical model that directly ties the fluid pressure in the subsurface during the injection to observations of induced microseismicity. This tractable model includes key physical parameters that affect fluid pressure, rock failure, and seismic wave propagation. It is also amenable to a rigorous uncertainty quantification analysis of the forward model and the inversion. We have used this probabilistic rock failure model to invert for fluid pressure during injection from synthetically generated microseismicity and to quantify the uncertainty of this inversion. The results of our analysis can be used to assess the effectiveness of microseismic monitoring in a given experiment and even to suggest ways to improve the quality and value of monitoring.

Fluid pressure waves trigger earthquakes

AbstractFluids—essentially meteoric water—are present everywhere in the Earth's crust, occasionally also with pressures higher than hydrostatic due to the tectonic strain imposed on impermeable undrained layers, to the impoundment of artificial lakes or to the forced injections required by oil and gas exploration and production. Experimental evidence suggests that such fluids flow along preferred paths of high diffusivity, provided by rock joints and faults. Studying the coupled poroelastic problem, we find that such flow is ruled by a nonlinear partial differential equation amenable to a Barenblatt-type solution, implying that it takes place in form of solitary pressure waves propagating at a velocity which decreases with time as v ∝ t [1/(n − 1) − 1] with n ≳ 7. According to Tresca-Von Mises criterion, these waves appear to play a major role in earthquake triggering, being also capable to account for aftershock delay without any further assumption. The measure of stress and fluid pressure inside active faults may therefore provide direct information about fault potential instability.

How does high-frequency sound or vibration activate vestibular receptors?

The mechanism by which vestibular neural phase locking occurs and how it relates to classical otolith mechanics is unclear. Here, we put forward the hypothesis that sound and vibration both cause fluid pressure waves in the inner ear and that it is these pressure waves which displace the hair bundles on vestibular receptor hair cells and result in activation of type I receptor hair cells and phase locking of the action potentials in the irregular vestibular afferents, which synapse on type I receptors. This idea has been suggested since the early neural recordings and recent results give it greater credibility.