Perforated Holes Research Articles

Optimizing extreme limited entry design for lateral heterogeneous reservoirs

Extreme limited entry (XLE) method can enhance hydraulic fracture uniformity by elevating wellbore pressure to overcome reservoir heterogeneity. However, it increases surface pressure and decreases hydraulic fracturing efficiency. In this paper, the effects of stress shadow and heterogeneity of the lateral breakdown pressure on fracture propagation are numerically studied, from which an optimization method is proposed for the XLE design with the minimal requirement of fracturing pressure. Initially, the unconventional fracture model is applied to analyze fracture propagation in formations with homogeneous geomechanical parameters and various perforation designs. Fracture length distribution is correlated with perforation friction, revealing insights into the influence of geomechanical parameters and fracture spacing. Then, the uniformity of fracture propagation is assessed for different XLE designs by varying lateral breakdown pressures. Simulation results are utilized to develop a cross-plot of fracture length distributions vs normalized perforation frictions for optimizing an XLE design. In homogeneous reservoirs, decreasing perforation spacing and increasing perforation hole erosion rate slow down the reduction in the fracture length distribution span with perforation friction, necessitating a higher perforation friction for uniform fractures. In all simulated cases, a similar trend is observed when the distribution of fracture lengths is plotted vs the normalized perforation friction to the difference of breakdown pressure within one fracturing stage. It is recommended that this normalized value be maintained above 2 in an XLE design. This new plot makes the conventional horn-shaped plot more applicable to reservoirs with heterogeneous lateral breakdown pressures.

Numerical study on perforation damage and fragmentation of reinforced concrete slab under close-in explosion

Reinforced concrete (RC) structure is prone to suffer localized damage when exposed to close-in explosions. Spalling damage might occur due to the reflected tensile stress wave exceeding the concrete dynamic tensile strength. When the blast wave is intensive enough, it can also cause significant crushing damage on the contact surface, potentially leading to perforation when the crushing depth aligns with the spalling depth. This perforation/spalling damage can generate a large number of secondary fragments with high ejecting velocities. Additionally, the blast wave might pass through the perforation hole and cause further acceleration of the secondary fragments. In the author’s previous study, an ALE-FEM-SPH numerical model was established and validated with the existing testing data for the prediction of spalling damage as well as fragment sizes and velocities. As a continuous work, this study conducts numerical simulations to predict the perforation damage and fragmentation under higher-intensity blast loading. The results including centre perforation hole, spalling area on back surface, fragment ejecting velocities, fragment landing distance and fragment characteristics distributions are reported and studied. The acceleration effect on the secondary fragments by the traversed blast wave that further carries the fragments flying is also investigated. The numerical results show that using the scaled distance Z might not reliably quantify the perforation/spalling damage under close-in cylindrical TNT explosion. Given the identical scaled distance, the scenarios with different combinations of charge weight and standoff distance can result in large variations up to 300% in the predictions of damaged area and 50% for the maximum fragment ejecting velocities, respectively. A scaled blast parameter Z* is suggested and the empirical formulae are proposed for better quantification of the damaged area of RC slab as well as the fragment velocity and kinetic energy under close-in cylindrical TNT explosions.

Characteristics of ejecta resulting from hypervelocity impact on Al/Mg explosive welding clad materials

In this study, we propose the use of a clad material, created from aluminum alloy A1100P-H24 and magnesium alloy AZ31B-H24 through explosive welding, as a Whipple shield for space applications. Two kinds clad materials with thickness ratios of Mg: Al = 0.5: 0.5 and Mg: Al = 0.7: 0.3 made from explosive welding, are compared to the current standard, the 1 mm thick A6061-T6 Whipple shield utilized in the international space station. By explosive welding low density, high specific strength, and high impact strength magnesium alloy with aluminum alloy, clad materials achieved 16.8% and 23.7% reduction in area density compared to A6061-T6. In the context of space debris mitigation, we performed hypervelocity impact tests on these clad materials. Detailed comparisons were made between the impact characteristics of the explosive welded clad materials and A6061-T6 by examining the perforation hole size and shape, and by collecting and analyzing the ejecta produced during impact. The experimental results revealed that the clad material with the thickness ratio of Mg: Al = 0.7: 0.3 experienced delamination at the material interface due to the penetration of projectile. On the other hand, the Mg: Al = 0.5: 0.5 clad material exhibited a perforation hole pattern comparable to that of monolithic aluminum and magnesium alloy materials. The cumulative number distribution of ejecta indicated that the clad material with a Mg: Al = 0.5: 0.5 ratio could reduce ejecta production. To further evaluate interface delamination, post-impact ultrasonic analyses were performed on the clad materials.

Retrobulbar haemorrhage and globe perforation after botulinum toxin injection into the medial rectus

Aims/Purpose: The aim of this communication is to show a recent case of both retrobulbar haemorrhage (RH) and probable globe perforation (GP) after botulinum toxin (BT) injection in the medial rectus of the right eye.Methods: We selected a recent case seen at our hospital. A 5u BT injection was performed under topical anaesthesia and guiding electromiography into the medial rectus due to a VI cranial nerve palsy. 2 min later the patient claimed intense pain and we evidenced a sudden growing periocular oedema and progressing exophthalmos. Retrobulbar haemorrhage was diagnosed and immediate canthotomy and cantholisys were performed, with consequent haemorrhage drainage. In the 24 h follow‐up visit, our patient claimed blurry vision and floaters. VA RE was 0.3 (before BT 0.7). Important corneal oedema and 3–4 + tyndall was observed. In the funduscopic exploration severe hemovitreous was observed; and an ocular ecography was performed, which showed no signs of retinal disruption. As vitreous started clearing and VA and floaters improved, observational treatment was decided. When we became able to see the retina with detail a possible perforation hole was seen in the infero‐medial quadrant, with no signs of traction or retinal elevation.Results: 3 months later, VA was 0.8 e° 1. Funduscopy showed an applied retina, with only a few persistent fibrine remainders in the inferior quadrant. Good‐coloured optic disc, with physiologic excavation and no signs of atrophy.Conclusions: Eventhough RH and GP are quite rare complications after BT infection, we should always take them into consideration. We also wanted to highlight these complications treatment. RH: Immediate canthotomy and cantholysis must be performed GP: close observation must be followed in order not to miss a retinal detachment. Plus, to avoid them we should be careful to perform the right technique and to use the electromiograph to guide us into the muscle.

Sound absorption of acoustic resonant absorbers with rough oblique perforations

Micro-perforated panel sound absorbers are widely used in the field of noise reduction due to their good sound absorption performance. For micro-perforated panel, the acoustic impedance characteristics of the perforation hole play an extremely important role in the sound absorption performance. Here, the acoustic metamaterial in the form of a perforated panel with rough oblique holes is proposed for low-frequency sound absorption. By introducing surface roughness, the acoustic performance of the oblique perforation holes can be adjusted, and the low-frequency sound absorption performance of the perforated panel sound absorber is improved. The theoretical prediction of sound performance has been verified by finite element simulation, and a good consistency has been achieved. The results show that the introduction of surface roughness effectively reduces the resonant frequency and increases the value of sound absorption peak. The introduction of surface roughness and oblique configuration can provide additional acoustic resistance and reactance for impedance matching with air without increasing the thickness of the structure, resulting in more effective low-frequency sound absorption. Physically, the surface roughness causes the periodic concentration effect of the fluid vibration in the hole, which increases the viscosity loss and improves the sound absorption performance of the sound absorber. The theoretical and the numerical models, as well as the low-frequency perfect sound absorption performance (α>0.99) of the proposed metamaterial, are validated by experimental measurements. This work is of great significance to the application of perforated panel absorbers in low-frequency sound absorption.

Squeeze‐film damping model of perforated plate considering border effect

AbstractThe squeeze‐film damping (SQFD) is an important dissipation mechanism of Micro‐Electro‐Mechanical Systems resonators. The current SQFD models of perforated plates treat borders of plate and holes as the constant pressure boundary, without considering border effect. In this paper, the border effect on SQFD is studied by expanding simulation area. At the same time, based on the research of non‐perforated plate border effect, the calculation size of the perforated plate hole cell is modified, and the modified SQFD model of the perforated plate has been built. Compared with simulation results, it shows the border effect has a great influence on SQFD of perforated plate. The precision of the modified model is higher than that of recent models. For a rectangular plate, the maximum error of the modified model is 12%, while for the recent model it is 40%. For a circular plate, the modified model is 38%, while the recent model is 58%.

Evaluation of perforation holes and ejecta from 6000 series aluminum alloys in hypervelocity impacts

Evaluation of perforation holes and ejecta from 6000 series aluminum alloys in hypervelocity impacts

Sound Absorption Performance of Coir Fiber/Polylactic Acid Composite Microperforated Panel

Microperforated panel (MPP) is considered a unique and promising sound absorber, as its sound absorption performance depends on parameters such as perforation ratio, perforation diameter, and air gap thickness. In this study, the MPP was fabricated through conventional mixing, granulating, and hot compression methods. The MPP was made from coir fiber/polylactic acid (PLA) composite, outside the norm of using metallic materials to produce MPP. The panel's sound absorption performance was measured using an impedance measurement tube and then compared with pure PLA MPP, which was taken as a benchmark for this study for a fair comparison. The MPP produced in this study demonstrated outstanding sound absorption performance due to its porous and tortuous structure. The porous and tortuous structure coincided with the perforated hole mechanism in absorbing sound; thus, the performance was better than pure PLA MPP, which did not possess an apparent porous and tortuous structure. This study proved that natural fiber composite has considerable potential to be used for MPP production, as it is a sustainable and natural resource that brings less harm to the environment compared to the common usage of metallic materials.

Construction and application of flow pressure drop model of perforated well considering pressure loss of perforation hole

Perforating well is one of the main production wells in reservoir development. Perforating effect directly affects well production, so the optimization of perforating parameters has attracted wide attention. Because pressure difference serves as the driving force for fluid flowing from formation to wellbore, it is important to understand the composition of production pressure difference in perforating well, which can guide the optimization of perforating parameters and the evaluation of perforating effect. In order to clarify the composition of production pressure difference during the production process of perforated wells, a pressure drop model pressure drop model is established based on fluid mechanics theory, which includes a pressure drop model of formation and a pressure drop model of perforation hole. The pressure drop model of formation is firstly constructed based on the Darcy's law and the equivalent resistance method, and the pressure drop model of perforation hole is built by the fluid tube-flow theory. Secondly, the numerical calculation method is adopted to realize the coupling solution of models, and the accuracy of this model is verified by comparison of the Karakas-Tariq model. Finally, the effects of formation physical properties and perforating parameters on flow pressure drop are discussed. The results show that there is a difference of more than 2 orders of magnitude between the pressure drop generated in perforation hole and flow pressure difference, and pressure drop of perforation hole can be neglected in practical applications. Comparing with medium–high permeability reservoirs, optimizing perforation parameters in low permeability reservoirs has a more significant impact on flow pressure drop. Among perforating parameters, perforation length and perforation density have great influence on flow pressure difference, while perforation diameter and phase angle have relatively little influence. These results have certain guiding significance for optimizing perforating parameters in different permeability reservoirs.

Farklı açılardaki çeşitli çokgen delikli kare plakların burkulma analizi

Buckling of the plates is of great importance in design of structures. If the plate has a hole because of necessity, hole area and shape also affect the critical buckling loads. In this study, buckling analyses of perforated simply supported square plates with various perforation patterns and different loading types were investigated. Three different perforation patterns as circular, hexagonal and square with different orientations were considered. In order to investigate the slenderness ratio effect, samples were calculated with three different ratio values of 100, 20 and 10. The samples were loaded with four different in-plane loads to examine the effect of loading type. Analyses were performed by using a general purpose finite element program and critical buckling loads were determined depending on the orientation angles for square plate models with different hole perforations. The critical buckling load is independent from the orientation angle for circular perforated plates but depends on for hexagonal and square hole perforations. For these plates buckling analyses were performed for different orientation angles of 0 degrees to 90 degrees. The results show that the calculated critical buckling loads did not remain the same although the hole areas were the same.

Investigation of casing stress distribution and parameter optimization during the transient impact process of multi-hole perforation operations

Perforation operation is critical in bridging completion and production enhancement operations. At the same time, the perforation parameters also affect the structural integrity of the casing. Still, there are fewer studies on the stress distribution of the casing under the blast transient impact loading of multi-hole perforation. To address this, considering the engineering application of helical perforation in unconventional oil and gas reservoirs, a three-dimensional numerical model of perforating charge-casing-cement sheath-formation is established, and the Holmquist-Johnson-Cook (HJC) rock dynamics material model, as well as the fluid–solid coupling and Arbitrary Lagrange-Euler (ALE) algorithms. On this basis, the variation rule and distribution characteristics of the effective stress in the double-perforation holes stress superposition area under different perforation density, phase angle, and geostress conditions are analyzed with the casing strength safety threshold as the optimization judgment condition of perforation parameters. The research results show that the numerical simulation result has good consistency in the results of engineering practice, perforation aperture diameter error is 3.04%, and jet head velocity error is 6.85%. The variation rule of perforation density and phase angle has a significant effect on the effective stress distribution in the stress superposition area around the hole: with the decreasing perforation density or increasing phase angle, the casing stress superposition area in the middle part of the neighboring perforation holes is gradually narrowed down, and when the perforation density is more than 9 P/m and 51°, the casing stress in the stress superposition area between the perforated holes is lower than the safety threshold value. With the increasing ground stress, the stress in the middle of the neighboring perforated holes increases continuously, showing a quadratic function change trend. The perforation density should be appropriately reduced, and the phase angle should be increased when the geostress is high to ensure the integrity of the casing structure after the perforation operation. The research results can provide a practical reference for conducting perforation engineering operations and optimizing perforation parameters.

Research on the erosion law of shale gas casing perforation hole during fracturing

During the fracturing process of shale gas wells, the high-speed injection of sand-carrying fluid throttles at the perforation casing hole, resulting in erosion at the hole, increasing the geometric parameters of the orifice and even producing cracks, affecting the fracturing construction effect and safety. Therefore, the flow field, the movement trajectory of particles and the erosion law of the perforated holes under different displacement and pump pressure were analyzed by using numerical simulation software and Euler-Lagrangian particle tracking theory, and the simulation analysis results were verified by the full-size physical erosion test of the perforated orifice of the casing. The analysis results show that with the increase of displacement, the erosion rate of the eyelet continues to increase, and the erosion rate of the eyelet in the direction of the liquid inlet is significantly greater than that of the bottom of the casing, and the degree gradually decreases in all directions. Increasing the fracturing construction displacement not only increases the erosion rate and diffusion area at the borehole, but also increases the erosion rate of the pipe wall near the borehole, which will accelerate the thinning of the wall thickness of the casing and affect the service safety of the perforated section casing.

Modified Iowa Formula for Buried Pipes with a Partial Loss of Soil Support in Its Invert Region due to Perforation Holes and Soil Erosion

Modified Iowa Formula for Buried Pipes with a Partial Loss of Soil Support in Its Invert Region due to Perforation Holes and Soil Erosion

Sustainable Perforated Acoustic Wooden Panels Designed Using Third-Degree-of-Freedom Bezier Curves with Broadband Sound Absorption Coefficients.

The current interior design scope places high demands on acoustic treatment manufacturers. The state of the art does not provide satisfactory material proposals for architects to satisfy design needs. There is a need for a novel approach concerning decorative, recognized materials that adapts them to the acoustic surface properties. The final design proposed in this study presents a modern functional solution with high acoustic properties, which can be produced with sustainable materials such as FSC wood and has a low environmental impact because of its low waste production. This research presents the complete design process of a novel type of wooden acoustic panel. A comprehensive explanation of the scientific development is covered, including basic material testing in an impedance tube, FEM simulations of the initial designs, and final measurements in a reverberation chamber. The solution's novelty is based on the optimized placement of the perforation holes on the surface of a wooden overlay using a ship deck optimization algorithm. The methods used cover the original solution of mixing FEM modeling of the surface impedance with the application of the Jeong-Thomasson correction for random incidence sound absorption coefficient simulation. The contribution of this research is the development of wooden perforated panels with Class A sound absorption and an overall depth of 90 mm, including the 50 mm depth of the backing material. The discussion will explain the difficulties of working with this material and the need for a combination of the aesthetic and acoustic sides of the project.

Squeeze cementing of micro-annuli: A visco-plastic invasion flow

Squeeze cementing is a process used to repair leaking oil and gas wells, in which a cement slurry is driven under pressure to fill an uneven leakage channel. This results in a Hele-Shaw type flow problem involving a yield stress fluid. We solve the flow problem using an augmented Lagrangian approach and advect forward the fluid concentrations until the flow stops. A planar invasion and a radial (perforation hole) invasion flow are studied. The characteristics of the flow penetration are linked to the channel thickness profile. The distribution of streamlines, flowing and non-flowing zones, evolves during the invasion flow. An interesting aspect of the results is the extreme variability in penetration metrics computed. These depend not only on the stochastic nature of the microannulus thickness, which has significant natural variation in both azimuthal and axial directions, but also on the “luck” of where the perforation hole is, relative to the larger/smaller microannulus gaps. This may explain the unreliability of the process.

Energy and exergy analysis of a cross flow solar air heater for thermohydraulic performance augmentation

This study numerically examines the enhancement of thermo-hydraulic efficiency of a cross flow solar air heater (SAH) for Reynolds number ranging from 3000 to 21000. The thermal performance is investigated for various perforation hole diameters of absorber plate and varying number of rows of holes. Discrete Ordinates radiation model is used to simulate the solar radiation heat interactions within the computational domain. Maximum thermo-hydraulic efficiencies of 86.51% and 85.15% are observed for configurations with 3 rows and 4 rows of perforation holes with hole diameter ratio of 0.06 and 0.07 respectively. The maximum exergy efficiency is found to be 5.28%. The system's enviro-economic analysis shows that the CO2 mitigation rate is 1.12 t CO2/annum, whereas the environmental cost is 16.31 $/year. The exergo-economic parameter is computed as 1.18 kWh/$, while the energy cost is calculated as 0.049 $/kWh. Additionally, it is determined that the energy payback period is 5 months while the exergy payback period is 22 years. The heat map for the various configurations shows the economical operating range of the air heater. The envisaged SAH has the advantage of completely decimating the laminar sublayer throughout the absorber plate due to cross flow movement of air through the absorber plate unlike the conventional SAH.

Acoustic Attenuation Performance Analysis and Optimisation of Expansion Chamber Coupled Micro-perforated Cylindrical Panel Using Response Surface Method

This paper describes boundary element method (BEM), experimental and optimization studies conducted to understand the potential of expansion tube coupled micro-perforated cylindrical panel (MPCP) to enhance the acoustic attenuation for in-duct noise control issues. Due to complex structure of the MPCP and for the correct prediction of acoustic attenuation, BEM is adopted on the basis of PLM Simcenter 3D software to compute the sound transmission loss (TL). As the MPCP is cylindrical in-shape with numbers of sub-milimeter holes, additive manufacturing based 3D printing was utilized for the model prototyping to reduce current design limitation and enabled fast fabrication. The TL measurement based two-load method is adopted for modal validation. Subsequently, a parametric studies of the MPCP concerning the perforation hole diameter, perforation ratio and depth of air space are carried out to investigate the acoustical performance. Optimization via response surface method (RSM) is used as it allows evaluating the effects of multiple parameters as required in this study. The model validation result shows that the error between the BEM and and measured values is relatively small and show a good agreement. The R-square value is 0.89. The finding from parametric study shows that a widen peak attenuation can be achieve by reducing the perforation hole diameter and one way to increase the transmission loss amplitude is by increasing the air cavity depth. Finally, the optimized MPCP model was adopted to the commercial vacuum cleaner for the verification. The sound pressure level (SPL) of the vacuum cleaner is significantly attenuated within the objective frequency of 1.7 kHz and its A-weighted SPL is reduced by 1.8 dB.

Optimization of Device Parameters for Back‐Contact Transparent Conductive Oxide–Less Dye‐Sensitized Solar Cells Fabrication

Transparent conductive oxide–less (TCO‐less) dye‐sensitized solar cell (DSSC) has been constructed and characterized employing mesoporous TiO2‐coated stainless‐steel mesh (S‐S‐mesh or Mesh) as a bendable photoanode and iodine‐based redox electrolyte. Efforts have been directed toward optimizing electronic parameters to enhance the power conversion efficiency (PCE) of TCO‐less DSSC to equalize its TCO‐based DSSC counterpart. It is found that protection of Mesh is essential for increasing the PCE of TCO‐less DSSCs employing iodine electrolyte as assured by suppressed reverse saturation current and better diode factor. The PCE of 5.6% is obtained with TCO‐less DSSC compared with TCO‐based DSSC with PCE of 6.09%. A bit of decrease in PCE with TCO‐less DSSC is due to larger resistance in TiO2/dye/electrolyte as well as within electrolyte as evident by electrochemical impedance spectroscopy (EIS) study owing to the Mesh having perforated holes and larger thickness of electrolyte absorbing sheet of the porous polytetrafluoroethylene film (35 μm) compared to TCO‐based DSSC without any barriers and lower electrolyte layer thickness of 25 μm.

Experimental and Numerical Study of the Strength Performance of Deep Beams with Perforated Thin Mild Steel Plates as Shear Reinforcement

This study aims to investigate a new shear reinforcement method which utilizes thin mild steel (TMS) plates as shear reinforcement in deep beams to replace conventional reinforcement. Thirteen reinforced concrete deep beam specimens with three different plate thicknesses and four varying perforated hole arrangements on the TMS plates were experimentally tested to determine the load-carrying capacity and crack pattern. The experimental results indicate that the 2.0 mm thick TMS plate has the highest load-carrying capacity. Among the four different hole arrangements on the TMS plates, the perforated plates with a three-column hole arrangement show the best performance in terms of load-carrying capacity, with a 2.9% increment against the control beam specimen. The specimens also demonstrated compatible elastic stiffness with the control beam that used conventional shear links. This shows that TMS plates have the potential to replace conventional shear links in deep beams. This proposed method also changed the failure mode from conventional diagonal shear tension failure to a combination of flexural failure and shear deformation. A numerical model was developed and was found to have a good correlation with the experimental results, demonstrating potential for use in future parametric investigations on deep beams and cost reduction in future experimental work.

Cryogenic Fracture Proliferation from Boreholes under Stresses

Cryogenic fracturing has been explored in recent years as a waterless fracturing method for well stimulation to avoid issues encountered in water-based hydraulic fracturing. Cryogenic stimulation using liquid nitrogen applies large thermal gradients on reservoir rocks to induce fractures. This study investigates the initiation and proliferation of cryogenic fractures from boreholes under external stress on specimens. We flowed liquid nitrogen through boreholes drilled through the center of transparent PMMA cylinders under uniaxial stress and monitored fracture proliferation, temperatures, and borehole pressures. Our results show that the effect of stress resembles that of hydraulic fractures such that fractures propagate more in the direction of the stress. Under loading perpendicular to the borehole axis, a cloud of annular and longitudinal fractures extends more in the direction of loading. Under loading parallel to the borehole axis, longitudinal fractures dominate, and annular fractures become more suppressed and more sparsely distributed than those of unconfined specimens. Even if fractures are driven to initiate against the influence of stress, such as those from a boundary edge of a high stress concentration, they gradually deflect in the direction of stress, similar to hydraulic fractures from perforation holes that curve toward a direction perpendicular to the minimum stress direction.