Compressional Energy Research Articles

Assessment of hydraulic fracture height and distribution using timelapse crosswell shear-wave data

An in-depth study of the impact of hydraulic fracturing operations on the Marcellus shale formation and overburden is presented by analyzing a unique timelapse crosswell seismic survey suitable for four-component shear wave vector rotations in order to study fracture azimuth and intensity. The borehole source used for the survey generated both oriented compressional and shear wave energy, and the seismic acquisition included perpendicular source orientations at each shot level to allow isolation of fast and slow shear modes using the Alford rotation and linear transform technique. Estimates of fast shear azimuth and slow shear time delay before and after hydraulic fracturing indicate fracture creation throughout the overburden above the Marcellus shale and a possible vertical breach of the bounding Tully limestone formation. The magnitude of the timelapse change is consistent between travel-time and slow shear lag inversion, but the absolute change is small, suggesting that the increase in fracture intensity may not be significant. These results point to operational inefficiencies during hydraulic fracturing operations that could negatively impact production and pose risks to future development. The study demonstrates the value of crosswell seismic surveys for reservoir monitoring and highlights observations that might be missed by a monitoring program that does not include timelapse seismic data and analysis of shear wave changes due to hydraulic fracturing.

A multi-cycle pump for efficient separation of CO2 or other trace gas from a mixture of gases

An idealized gas separation pump is described for a membrane filtration system that conserves compressional energy by transferring it from one component to another operating at a different phase of the compression-decompression cycle. An example of the basic principle, we consider a pump that resembles an internal combustion engine with pistons in cylinders and three valves, one for mixed gas input, another for select gas output through a membrane, and a third for non-select gas output to the environment. With the transfer of compressional energy from the decompressing cylinder to the compressing cylinder, the energy required is the sum of frictional losses and the amount needed to compress only the trace gas that is to be separated. Compressional energy for the non-select is recovered. The mechanical energy required is the energy to compress the cylinder, NRT(lnC−1+1∕C)∼3NRT in the isothermal case for number of moles of select gas, N, gas constant R, temperature T, and compression factor C ∼ 50, multiplied by 1 + 2ϵ∕f ∼ 2 for frictional loss fraction ϵ ∼ 6% comparable to that in internal combustion engines and an input select gas molar fraction f ∼ 10% as for CO2 in flue gas. With T = 300 K and N = 2.3 × 104 per ton for CO2, this energy becomes ∼ 6NRT ∼ 94 kWh/tCO2. The advantages of a system like this are that the compression ratio through the membrane can be large and the timescale for compression can be adjusted to maximize the throughput for a given selectivity, overcoming the usual selectivity-permeance trade-off. A disadvantage is that the throughput is generally low for volumetric pumps at practical scales.

A method for near-perfect gas separation in two interconnected streams

Gas separation such as CO2 from N2 in flue gas is an important step in reducing greenhouse gas emission. We discuss a separation method that moves mixed gas between two tracks at different pressures with ever-increasing purity at each stage along the tracks. Designs for adsorbents driven by volumetric pumps and membranes driven by a pressure drop are illustrated. For selectivity exceeding 10 in a three-stage system, the purity of the CO2 output is 97.8% with 99.75% recovered. For a six-stage example, the purity of CO2 is 99.996% and 99.9996% is recovered. The cost of compression is estimated from the number of times the two components have to be pressurized as they move between the tracks. For large selectivity, the effective number of times for CO2 is 2 for the adsorbent case and 3 for the membranes in the three-stage design; these numbers are 5 and 6 in the six-stage design. As a result, the compressional energy requirement per input mole is RTln⁡(C)(1+Af) in the isothermal case for compression factor C, effective number of re-compressions A, and input CO2 fraction f. This compressional energy exceeds the minimum energy from entropy by the factor ∼(1+Af)/f if C=1/f for efficient membrane use.

Study of the compression properties of welded seams formed using hot wedge, hot air, ultrasonic, and high-frequency welding techniques

The compression properties of welded seams depending on welding parameters using the hot wedge and hot air welding technique, ultrasonic welding technique, and high-frequency welding technique were studied. The compression properties, expressed by parameters such as compressional energy WC, compressional resilience RC, linearity LC, and compressibility C, are important information about the welded seam quality in terms of touch, voluminosity, stiffness, and flexibility of the welded seam. KES-FB and FAST measurement systems were used to test the compression properties of the welded seams. Based on the analysis of the results obtained, the influence of the welding parameters on the compression properties of the welded seam was determined. The results of the investigation showed that improperly selected welding parameters, such as the supply or introduction of too much heat into the material to be welded or too long exposure of the material in the weld zone to heat, result in welded seams with expressive extrusion edges, which affects the quality of the welded seams. These welded seams have very low values of compressional resilience RC and very high values of compressional energy WC and compressibility C.

Production efficiencies of sound waves in the intracluster medium driven by AGN jets

ABSTRACT Feedback from active galactic nuclei (AGNs) is believed to be the most promising solution to the cooling flow problem in cool-core clusters. Dissipation of sound waves is considered as one of the possible heating mechanisms; however, its relative contribution to heating remains unclear. To estimate the energy budget for heating, we perform 3D hydrodynamic simulations of AGN jet injections in a Perseus-like cluster and quantify the amount of energy stored in the forms of weak shocks and waves. We find that, for a single jet injection with typical parameters in cool-core clusters, ${\sim}9{{\ \rm per\ cent}}$ of the total jet energy is stored in compressional waves (including both shocks and waves). However, due to the destructive effects among randomly phased waves as well as the dissipation of shock energies, in our simulations including self-regulated AGN feedback, no more than $3{{\ \rm per\ cent}}$ of the total injected energy goes into compressional waves. We further separate the energy contribution from shocks and waves and find that, for a single outburst, the shocks can only contribute to ${\sim}20{-}30{{\ \rm per\ cent}}$ of the total compressional energy in the inner radii and quickly dissipate away. In the self-regulated case where shocks are repeatedly generated, shocks completely dominate over sound waves in the inner region and can still provide ${\sim}40{-}50{{\ \rm per\ cent}}$ of the total compressional energy at outer radii. Our results suggest that the production of sound waves is not as efficient as what was previously found, and thus sound wave dissipation may be a subdominant source of heating in cool-core clusters.

Effect of compressional behaviour and sewing machine foot pressure on sewing thread consumption

Effect of compressibility and foot pressure on the consumption behaviour of sewing threads in case of single and double-layered denim fabrics has been investigated. Experiments involve fabric thickness of three different denim samples (cotton, and 90/8.5/1.5% & 92/6.5/1.5% cotton/polyester/elastane) and their compression properties measurement using Kawabata device. A relationship between compressional energy and consumed sewing thread values using lock stitch type 301 has been investigated. Based on this, accuracy of the coefficient of regression (close to 1) has been observed, indicating the positive relationship between compressibility property and sewing thread consumption behaviour. Implementation of software can help the industries to minimize their consumption errors and approximations. Nevertheless, under the same pressure value applied by the foot pressure, the thickness values of sewed layers can decrease differently as a function of their compressional resilience. Thus, it is obvious that thicker fabrics display lower compressional resilience and vice versa, which encourages more consumption of sewing thread.

Evaluating an Unconventional Shale Completion with Repeat Crosswell Tomography

Evaluation of hydraulic fracturing relies on indirect inference from measurements that are distorted by distance and noise of various kinds, so reservoir monitoring technology that places the measurement as close to the completion as possible is important. Crosswell tomography is just such a technology, placing source and sensor in the plane of the feature to be analysed, and is an excellent technology for making in situ estimates of subsurface properties in simple geologic settings when source-receiver separation is small and when noise levels are low. Since these conditions are not typical in-field scale surveys of unconventional shales, this study overcomes these deficits by incorporating vertically transverse isotropy in raytracing and applying a strong source effort to increase signal-to-noise. The survey used Schlumberger’s Ztrac source and multicomponent geophones to both generate and record compressional and shear wave energy, matching baseline and repeat surveys within a few days of hydraulic fracturing to detect subtle timelapse changes prior to flowback and fluid diffusion. The result is a unique characterization of fracture creation due to hydraulic fracturing, highlighting an out of zone response and subsequent impact on the bounding limestone layers.

Quality control for the geophone reorientation of ocean bottom seismic data using k‐means clustering

ABSTRACTDuring ocean bottom seismic acquisition, seafloor multicomponent geophones located in rugose and sloping water bottom can be affected by skewed energy distribution, such as leaked shear energy on the vertical geophones and leaked compressional energy on the horizontal geophones. To correct for the tilted energy distribution, which is one of most effective preprocessing steps, a geophone reorientation step is applied. This is a simple and straightforward process that applies a 3‐dimensional rotation matrix with respect to the orientation angles. Since the reorientation process highly affects the outcome of the entire data processing workflow, it has to be accompanied by a careful quality control process to verify its validity for the whole survey area. In this study, we propose a quality control workflow for the geophone reorientation by using unsupervised machine learning. A correlation analysis is employed to compare numerical versus analytical solutions of both the azimuth and the incidence angles for the direct arrivals. A comparison of both solutions aims to generate correlation coefficients that are indicative of the accuracy of geophone orientation. The correlation coefficients are subsequently investigated by the k‐means clustering algorithm to differentiate and identify normally and abnormally deployed/reoriented geophones. Numerical experiments on a field ocean bottom seismic data set confirm that the proposed workflow effectively provides reliable labels for normally and abnormally deployed/reoriented geophones. The labelling assigned by the proposed quality control workflow is a suitable indicator for abnormalities in the geophone reorientation step and will be helpful for further investigation, such as re‐correction or removal of abnormally reoriented geophones.

New measurements of long-period radial modes using large earthquakes

SUMMARYRadial modes, nS0, are long-period oscillations that describe the radial expansion and contraction of the whole Earth. They are characterized only by their centre frequency and quality factor Q, and provide crucial information about the 1-D structure of the Earth. Radial modes were last measured more than a decade ago using only one or two earthquakes. Here, we measure radial modes using 16 of the strongest and deepest earthquakes of the last two decades. By introducing more earthquake data into our measurements, we improve our knowledge of 1-D attenuation, as we remove potential earthquake bias from our results. For mode 0S0, which is dominated by compressional energy, we measure a Q value of 5982, much higher than previously measured, and requiring less bulk attenuation in the Earth than previously thought. We also show that radial modes cross-couple (resonate) strongly to their nearest spheroidal mode due to ellipticity and inner core cylindrical anisotropy. Cross-coupling improves the fit between data and synthetics, and gives better estimates of the centre frequency and attenuation value of the radial modes. Including cross-coupling in our measurements results in a systematic shift of the centre frequencies of radial modes towards the Preliminary Reference Earth Model. This shift in centre frequencies, has implications for the strength of the radial anisotropy present in the uppermost inner core, with our cross-coupling results agreeing with lower values of anisotropy than the ones inferred from just measuring the modes in self-coupling (isolation). Furthermore, cross-coupling between radial modes and angular-order two modes provides constraints on cylindrical inner core anisotropy, that will help us improve our knowledge of the 3-D structure of the inner core.

A UK local seismic magnitude scale, MLP, using P-wave amplitudes

SUMMARYA local seismic magnitude scale, MLP, has been developed for the United Kingdom (UK) using automated measurements of 8902 half peak-to-peak vertical component seismic P-wave displacement amplitudes from 630 earthquakes. The measurement time window increases with source-to-receiver range such that MLP is sensitive to the dominant phase within the P-wavetrain at a given distance. To avoid contamination due to low-frequency noise, the P-wave amplitude measurements are made in the 1.5–30 Hz passband. A least-squares inversion was undertaken to estimate source size, distance and station effects. The distance effect values suggest that P-wave amplitude attenuation across the UK is low when compared to other tectonically stable regions. The station effects are broadly consistent with UK geology, with signal amplification observed within the sediments towards the south-east of the country. MLP has been tied to the UK local magnitude scale routinely estimated by the British Geological Survey (BGS, determined using S waves, and here denoted MLBGS). For earthquakes with MLBGS > 3, MLP exhibits a closer correspondence to the moment magnitude than MLBGS (i.e. MLP≈Mw). It is tentatively suggested that this reduction in bias is caused by the P-wave scale being less affected by along-path attenuation. The difference with respect to physical source scaling helps explain the divergence of the MLBGS and MLP scales at ML > 3. MLP allows a robust estimate of event size to be made for small events which predominantly generate P waves, for example, near-surface explosions. MLP values have been calculated for 239 explosive events, mostly mining blasts and munitions disposal. Although there is significant scatter, explosive events exhibit elevated MLP values compared to MLBGS, consistent with explosions generating proportionally more compressional wave energy than earthquakes. For example, 33 explosions at sea exhibit a median MLP–MLBGS value of 0.50 mag units. Despite its sensitivity to P-wave amplitude, MLP is not a more consistent estimator of explosive source size than MLBGS; the magnitude residuals (station estimate − event estimate) are slightly less for MLBGS compared to MLP. This is primarily due to variability of the P-wave amplitudes that cannot be explained by a 1-D distance correction. MLP should be considered as an additional tool for characterizing small seismic events within the UK.

Frequency-dependent AVO analysis

A method for generalizing the conventional amplitude variation with offset model from an isolated interface to a scattering reservoir interval is presented. The advantage of this new method is that it can provide enhanced detection of subtle reservoir and pore fluid properties. First- and second-order expressions for the reflected compressional wave energy from a specified heterogenous interval are given. These expressions are applied to two problems of interest for reservoir description. One application is discriminating low versus higher saturations of hydrocarbons, and the other is detecting the extent of vertical stratification within a reservoir. The first-order expression is used for determining hydrocarbon saturations, and the second-order expression is used for detecting the magnitude of fine-scale layering within a reservoir. Synthetic models and field data examples are used in demonstrating the applicability of the proposed method.

Langmuir films at the oil/water interface revisited

We studied monomolecular layers at the oil/water interface (O/Wint) in a Langmuir interfacial trough using egg-yolk phosphatidylcholine (EPC) (the model phospholipid) and Vaseline (VAS) as oil phase. The temporal dynamics in the surface pressure (π) evolution depended on the method (spreading/adsorption) used for monolayers preparation and reflected the different distribution of EPC between all the system compartments (bulk phases and interfaces). We distinguished between EPC located either stable at the interface or hopping between the interface and bulk phases. The size order of the apparent mean molecular area, at constant π, of EPC at different interfaces (EPCO/W > EPC/VAS0.02;A/W > EPCA/W), suggested that VAS molecules intercalated between the hydrocarbon chains of EPCO/W, at a molar fraction xVAS > 0.02. However, EPC/VAS0.02;A/W showed the highest compressional free energy. This leaded us to study the EPC/VAS0.02 mixture at A/W by Brewster Angle Microscopy (BAM), finding that upon compression VAS segregated over the monolayer, forming non-coalescent lenses (as predicted by the spreading coefficient S = −13 mN/m) that remained after decompression and whose height changed (increase/decrease) accompanied the compression/decompression cycle. At the O/Wint, while some VAS molecules remained at the interface up to the collapse, others squeezed out towards the VAS bulk phase with an energy requirement lower than towards the air.

Highly Compressible Cross-Linked Polyacrylamide Hydrogel-Enabled Compressible Zn-MnO2 Battery and a Flexible Battery-Sensor System.

The fast advancement in flexible and wearable electronics has put up with new requirements on the energy storage device with improved tolerance to deformation apart from offering power output. Despite the tremendous progress in stretchable energy storage devices, the compressional energy storage devices have indeed received limited research attention. In this work, an intrinsically compressible rechargeable battery was proposed using the Zn-MnO2 chemistry and a cross-linked polyacrylamide hydrogel electrolyte. Interestingly, the battery exhibited not only good energy storage performances but also excellent tolerance against large compressional strain without sacrificing the energy storage capability. It was also found that the ionic conductivities of the hydrogel increased with the values of the compressional strain, leading to an enhanced electrochemical performance. More importantly, upon dynamic compression, the voltage output of the battery can be very stable and reliable. Consequently, the battery assembled using the hydrogel electrolyte can be used to power a luminescent panel even with a 3 kg load on top of it. It was also demonstrated that the flexible sensor powered by our compressible battery exhibited similar and stable sensory signals compared with the same sensor powered by two commercial alkaline batteries. Furthermore, because of the excellent mechanical property of our battery, a smart wristband fabricated by integrating two battery packs and the flexible piezoresistive sensor could be powered and used to monitor the pressure exerted, demonstrating the battery's potential as the wearable power source for the flexible and wearable devices.

Prediction and analysis of compression behaviour of warp-knitted spacer fabric with cylindrical surface

Nowadays, applications of spacer fabric cover wider areas of technical textile. It is used in the automotive textile, personal protective clothing, sports textile, foundation garments, pads for swimwear, buffer clothing, medical textile etc. It does possess good recovery to compression, high bulk with relatively lightweight and very good moisture permeability. Almost in all applications, spacer fabrics are compressed by different parts of human body. Body parts have different shapes and curvatures. In all standard methods, spacer fabric compressibility is measured by a pair of flat circular plate which cannot represent a human body. The contour of body can be assumed as cylindrical with varying radius of curvature. So, it is necessary to understand the mechanism of compression of spacer fabric with cylindrical surface in order to understand the performance of the fabric under real-world dynamics. In this research, an effort is being made to predict the compression behaviour of warp-knitted spacer fabric by flat as well as cylindrical surface. Finite Element Models were designed on Abaqus/CAE platform to meet above requirement with variable circumstances. Experimental setup was also made to analyse cylindrical and flat compression at different circumstances. Results show that flat compression and cylindrical compression are largely deferred in terms of shape of load-deformation curve and compressional energy. Effect of variables on compression behaviour was also analysed. Model results were validated with experimental values. It is found that the proposed model has got a good agreement with the experimental results.

Three‐Dimensional Passive‐Source Reverse‐Time Migration of Converted Waves: The Method

AbstractAt seismic discontinuities in the crust and mantle, part of the compressional wave energy converts to shear wave, and vice versa. These converted waves have been widely used in receiver function (RF) studies to image discontinuity structures in the Earth. While generally successful, the conventional RF method has its limitations and is suited mostly to flat or gently dipping structures. Among the efforts to overcome the limitations of the conventional RF method is the development of the wave‐theory‐based, passive‐source reverse‐time migration (PS‐RTM) for imaging complex seismic discontinuities and scatters. To date, PS‐RTM has been implemented only in 2D in the Cartesian coordinate for local problems and thus has limited applicability. In this paper, we introduce a 3D PS‐RTM approach in the spherical coordinate, which is better suited for regional and global problems. New computational procedures are developed to reduce artifacts and enhance migrated images, including back‐propagating the main arrival and the coda containing the converted waves separately, using a modified Helmholtz decomposition operator to separate the P and S modes in the back‐propagated wavefields, and applying an imaging condition that maintains a consistent polarity for a given velocity contrast. Our new approach allows us to use migration velocity models with realistic velocity discontinuities, improving accuracy of the migrated images. We present several synthetic experiments to demonstrate the method, using regional and teleseismic sources. The results show that both regional and teleseismic sources can illuminate complex structures and this method is well suited for imaging dipping interfaces and sharp lateral changes in discontinuity structures.

Full Waveform Modelling for Subsurface Characterization with Converted-Wave Seismic Reflection

While a large number of reservoirs have been explored using P-waves seismic data, P-wave seismic survey ceases to provide adequate result in seismically and geologically challenging areas, like gas cloud, shallow drilling hazards, strong multiples, highly fractured, anisotropy. Most of these reservoir problems can be addressed using P and PS seismic data combination. Multicomponent seismic survey records both P-wave and S-wave unlike conventional survey that only records compressional P-wave. Under certain conditions, conventional energy source can be used to record P and PS data using the fact that compressional wave energy partly converts into shear waves at the reflector. Shear component can be recorded using down going P-wave and upcoming S-wave by placing a horizontal component geophone on the ocean floor. A synthetic model is created based on real data to analyze the effect of gas cloud existence to PP and PS wave reflections which has a similar characteristic to Sub-Volcanic imaging. The challenge within the multicomponent seismic is the different travel time between P-wave and S-wave, therefore the converted-wave seismic data should be processed with different approach. This research will provide a method to determine an optimum converted point known as Common Conversion Point (CCP) that can solve the Asymmetrical Conversion Point of PS data. The value of γ (Vp/Vs) is essential to estimate the right CCP that will be used in converted-wave seismic processing. This research will also continue to the advanced processing method of converted-wave seismic by applying Joint Inversion to PP&PS seismic. Joint Inversion is a simultaneous model-based inversion that estimates the P&S-wave impedance which are consistent with the PP&PS amplitude data. The result reveals a more complex structure mirrored in PS data below the gas cloud area. Through estimated γ section resulted from Joint Inversion, we receive a better imaging improvement below gas cloud area tribute to the converted-wave seismic as additional constrain.

An Overview on Piezoelectric Power Generation System for Electricity Generation

Coal, petroleum and natural gas will still be the basis of economic development for a long time. However, with a rapider consumption speed, these fossil fuels will be exhausted in the near future. In addition, the usage of these fossil fuels can also cause environmental pollution and greenhouse effect. To deal with energy security and environmental crisis, it is wise to work towards three directions: energy saving and emission reduction, energy recovery, exploration of new renewable energy. Currently, the electricity generation technology using piezoelectric material to recover the compressional or vibrational energy begins to draw attention. However, most of the researches are devoted to designing small self-powered devices. This paper presents an overview of the feasibility of piezoelectric power generation system for electric power system, in which the fundamentals of piezoelectric power generation and the feasible structure of the system are discussed.

Apparent Explosion Moments fromRgWaves Recorded on SPE

Abstract Seismic moments for the first four chemical tests making up phase I of the Source Physics Experiments (SPE) are estimated from 6‐Hz Rg waves recorded along a single radial line of geophones under the assumption that the tests are pure explosions. These apparent explosion moments are compared with moments determined from the reduced displacement potential method applied to free‐field data. Light detection and ranging (lidar) observations, strong ground motions on the free surface in the vicinity of ground zero, and moment tensor inversion results are evidence that the fourth test SPE‐4P is a pure explosion, and the moments show good agreement, 8×10 10 N·m for free‐field data versus 9×10 10 N·m for Rg waves. In stark contrast, apparent moments for the first three tests are smaller than near‐field moments by factors of 3–4. Relative amplitudes for the three tests determined from Rg interferometry using SPE‐4P as an empirical Green’s function indicate that radiation patterns are cylindrically symmetric within a factor of 1.25 (25%). This fact assures that the apparent moments are reliable even though they were measured on just one azimuth. Spallation occurred on the first three tests, and ground‐based lidar detected permanent deformations. As such, the source medium suffered late‐time damage. Destructive interference between Rg waves radiated by explosion and damage sources will reduce amplitudes and explain why apparent moments are smaller than near‐field moments based on compressional energy emitted directly from the source.

A Study of Compression Properties of Paper Towels with KES-F System

In this study, we chose 12 commonly available paper towels from the local market. The compression properties of the paper towels were examined by Kawabata Evaluation System for Fabric (KES-F). Three compression properties namely: (i) compressional linearity (LC), (ii) compression energy (WC) and (iii) compressional resilience (RC) were examined. The experimental results revealed that the compression properties varied within the different paper towels. RC vlaue was used as the key property for discussing the compression properties of paper towels. When different compression properties were correlated and analysed, it was found that no relationship was noted within different compression properties. On the other hand, there was not significant statistically relationship between weight and thickness to RC. It is hope that the results from this study can help the indurstry to improve the compression properties of paper towels for local market.

Mechanical properties and hand evaluation of hemp woven fabrics treated with liquid ammonia

The effects of liquid ammonia (L/A) treatment on the mechanical properties and hand of 100 % hemp woven fabrics were investigated by the KES-FB (Kawabata Evaluation System for Fabric). Tensile energy and tensile resilience were increased by the L/A treatment. Bending and shearing values such as bending rigidity, bending moment, shear stiffness, shear hysteresis of the L/A treated fabrics were lower than those of the untreated ones. Compressional linearity and compressional energy were decreased while the compressional resilience was increased by the L/A treatment. From the hand evaluation, the primary hand values as well as total hand value of the hemp fabric were markedly increased by the L/A treatment, especially when yarn number was fine. Therefore, L/A treatment was found to be an effective method of improving the flexibility and softness of hemp woven fabrics.