High-viscosity Fluid Research Articles

Effects of viscous dissipation in propagation of sound in periodic layered structures

Propagation and attenuation of sound through a layered phononic crystal with viscous constituents is theoretically studied. The Navier–Stokes equation with appropriate boundary conditions is solved and the dispersion relation for sound is obtained for a periodic layered heterogeneous structure where at least one of the constituents is a viscous fluid. Simplified dispersion equations are obtained when the other component of the unit is either elastic solid, viscous fluid, or ideal fluid. The limit of low frequencies when periodic structure homogenizes and the frequencies close to the band edge when propagating Bloch wave becomes a standing wave are considered and enhanced viscous dissipation is calculated. Angular dependence of the attenuation coefficient is analyzed. It is shown that transition from dissipation in the bulk to dissipation in a narrow boundary layer occurs in the region of angles close to normal incidence. Enormously high dissipation is predicted for solid–fluid structure in the region of angles where transmission practically vanishes due to appearance of so-called “transmission zeros,” according to El Hassouani, El Boudouti, Djafari-Rouhani, and Aynaou [Phys. Rev. B 78, 174306 (2008)]. For the case when the unit cell contains a narrow layer of high viscosity fluid, the anomaly related to acoustic manifestation of Borrmann effect is explained.

Controlling viscous fingering instabilities of complex fluids

Despite their aesthetic elegance, wavy or fingering patterns emerge when a fluid of low viscosity pushes another immiscible fluid of high viscosity in a porous medium, producing an incomplete sweep and hampering several crucial technologies. Some examples include chromatography, printing, coating flows, oil-well cementing, as well as large-scale technologies of groundwater and enhanced oil recovery. Controlling such fingering instabilities is notoriously challenging and unresolved for complex fluids of varying viscosity because the fluids’ mobility contrast is often predetermined and yet the predominant drive in determining a stable, flat or unstable, wavy interface. Here we show, experimentally and theoretically, how to suppress or control the primary viscous fingering patterns of a common type of complex fluids (of shear-thinning with a low yield stress) using a radially tapered cell of linearly varying gap thickness, h(r). Experimentally, we displace a complex viscous (PAA) solution with gas under a constant flow rate (Q), varied between 0.02 and 2 slpm (standard liter per minute), in a radially converging cell with a constant gap-thickness gradient, α=dh/dr<0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha = dh/dr < 0$$\\end{document}. A stable, uniform interface emerges at low Q and in a steeper cell (i.e., greater |α|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|\\alpha |$$\\end{document}) for the complex fluids, whereas unstable fingering pattern at high Q and smaller |α|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|\\alpha |$$\\end{document}. Our theoretical predictions with a simplified linear stability analysis show an agreeable stability criterion with experimental data, quantitatively offering strategies to control complex fluid-fluid patterns and displacements in microfluidics and porous media.

Experimental Investigation of Fracture Propagation in Clayey Silt Hydrate-Bearing Sediments

More than 90% of the natural gas hydrate resources are reserved as marine clayey silt sediments. It is of great significance to efficiently develop a clayey silt hydrate. At present, there are problems of low single well production and small depressurization range in its production test, which is still a long way from commercial exploitation. The combination of hydraulic fracturing technology and other methods such as depressurization method is regarded as one of the potential technical means to achieve the commercial exploitation of the hydrate. However, compared with shale gas reservoirs and coalbed methane reservoirs, clayey silt hydrate reservoirs have special mechanical properties, resulting in unique hydraulic fracturing processes. Therefore, it is necessary to study the fracture initiation and propagation laws of clayey silt hydrate reservoirs. To this end, we carried out large-scale (30 × 30 × 30 cm) true triaxial hydraulic fracturing experiments using a simulated material with similar mechanics, porosity, and permeability to clayey silt hydrate-bearing sediments. The effects of completion method, fracturing method, and fracturing fluid displacement on hydraulic fracture propagation of clayey silt hydrate-bearing sediments were studied. The results showed that a perforated completion can significantly increase the fracture reconstruction area and decrease the fracture initiation pressure compared to an open hole completion. Due to the small horizontal stress difference, it is feasible to carry out temporary plugging fracturing in clayey silt hydrate reservoirs. Temporary plugging fracturing can form steering fractures and significantly improve fracture complexity and fracture area. Increasing the fracturing fluid displacement can significantly increase the fracture area as well. When conducting fracturing in clayey silt hydrate-bearing sediments, the fracturing fluid filtration area is obviously larger than the fracture propagation area. Therefore, it is recommended to use a high-viscosity fracturing fluid to reduce the filtration of the fracturing fluid and improve the fracturing fluid efficiency. This study preliminarily explores the feasibility of temporary plugging fracturing in clayey silt hydrate reservoirs and analyzes the effect of completion methods on the propagation of fracturing fractures, which can provide a reference for the research conducted on the fracturing stimulation of clayey silt hydrate reservoirs.

The propagation of hydraulic fracture in layered coal seam: a numerical simulation considering the interface thickness based on the distinct element method

The intercalated layer of coal seam plays an important role in the propagation of hydraulic fracturing. To understand the role of the intercalated layer, a composite coal seam model considering the thickness of the intercalated layer was established. Based on the block distinct element method, the effects of rock structure (thickness of the coal seam and intercalated layer), rock properties (elastic modulus), and construction parameters (injection rate and fluid viscosity) on the penetration behavior of hydraulic fractures were analyzed. The results show that the intercalated layers influence the fracture deflection and have a hindering effect on fracture propagation. The thickness of the intercalated layer affects the stress on the bedding plane and the front edge of the fractures. On the contrary, the thickness of the coal seam mainly affects the penetration ability of hydraulic fractures and the extent of hydraulic fracture propagation. In addition, the elastic modulus of the intercalated layers and coal seams affects the hindering effect of the intercalated layer. The high injection rates reduce the hindering effect of the intercalated layer. When fracturing with a high-viscosity fluid, fractures are more likely to enter the intercalated layer. However, excessively high viscosity can make it difficult for fractures to penetrate the intercalated layer. This study can provide theoretical guidance for the fracturing of composite coal seams.

Study on Fracture Propagation Rules of Shale Refracturing Based on CT Technology

Reactivating oil and gas wells, increasing oil and gas production, and improving recovery provide more opportunities for energy supply especially in the extraction of unconventional oil and gas reservoirs. Due to changes caused by well completion and production in pore pressure around oil and gas wells, subsequently leading to changes in ground stress, and the presence of natural and induced fractures in the reservoir, the process of refracturing is highly complex. This complexity is particularly pronounced in shale oil reservoirs with developed weak layer structures. Through true triaxial hydraulic fracturing experiments on Jimsar shale and utilizing micro-CT to characterize fractures, this study investigates the mechanisms and patterns of refracturing. The research indicates: (1) natural fractures and the stress states in the rock are the primary influencing factors in the fracture propagation. Because natural fractures are widely developed in Jimsar shale, natural fractures are the main influencing factors of hydraulic fracturing, especially in refracturing, the existing fractures have a greater impact on the propagation of secondary fracturing fractures. (2) Successful sealing of existing fractures using temporary blocking agents is crucial for initiating new fractures in refracturing. Traditional methods of plugging the seam at the root of existing fractures are ineffective, whereas extensive injection of blocking agents, forming large “sheet-like” blocking bodies in old fractures, yields better sealing effects, promoting the initiation of new fractures. (3) Moderately increasing the pumping rate and viscosity of fracturing fluid is advantageous in forming “sheet-like” temporary blocking bodies, enhancing the complexity of the network of new fractures in refracturing. (4) When there is a high horizontal stress difference, after sealing old fractures, the secondary hydraulic fractures initiate parallel to and extend from the old fractures. In cases of low horizontal stress difference, the complexity of secondary hydraulic fractures increases. When the horizontal stress changes direction, the secondary hydraulic fractures also change direction. It is recommended to use high-viscosity fracturing fluid and moderately increase the pumping rate, injecting blocking agents to seal old fractures, thereby enhancing the complexity of the network of refracturing. These findings provide important technical guidance for improving the efficiency of shale oil reservoir development.

Experimental and CFD modeling of a progressive cavity pump (PCP) using overset unstructured mesh part 1: Single-phase flow

Progressive Cavity Pumps (PCP) are integral in industries for transporting high-viscosity fluids due to their efficacy. Nevertheless, their computational modeling via Computational Fluid Dynamics (CFD) poses challenges, primarily attributed to meshing algorithms and computational demands. This research underscores that structured meshes are not imperative for assessing PCP efficiency, given that operational parameters reflect a 10% accuracy when juxtaposed with experimental data. An overset mass conservation model was harnessed to rectify mass conservation errors and the computational burden from interpolation. The overset grid methodology emerged as a favorable technique for PCP modeling, with its applicability critically analyzed. Experimental data comparison revealed that variables like volumetric flow rate, power consumption, and efficiency were accurately depicted with a marginal error of less than 10%. Interestingly, while high-viscosity oils resonated with the Hagen-Poiseuille flow equation in clearance zones, water showcased elevated velocities, inducing a non-linear pressure profile. Analysis of slip components indicated that high-viscosity oils offered superior efficiencies due to augmented slip resistance. Thus, CFD modeling of PCPs across different viscosity spectrums is feasible without mandating operations to enhance mesh quality. This study pioneers in offering insights into PCP dynamics, emphasizing the accuracy and optimization potential of the overset unstructured mesh approach.

Clinical Application of Computed Tomography in the Surgical Treatment of Submandibular Sialocele and Sialoliths in Dog

A 10-year-old, 8-kg mixed-breed dog presented with a painless, soft, and tender submandibular swelling. Radiographs revealed an 8x6 cm ventral cervical mass with radiopaque spots. Fine needle aspiration showed high viscosity and yellow-tinged fluid, indicative of an inflammatory sialocele. After drainage, carprofen (4.4 mg/kg) was administered daily for one week, followed by prednisone (0.5 mg/kg) for the second week. However, the mass recurred after one month, necessitating a computed tomography (CT) scan for surgical management. CT imaging demonstrated an encapsulated fluid-attenuating mass in the submandibular region, containing sludges and calcified materials. Surgical excision confirmed a submandibular mucocele with sialoliths. Infrared spectroscopy revealed a high protein concentration in the sialoliths. The CT scan facilitated accurate diagnosis and informed the treatment plan for this canine cervical mass, encompassing submandibular mucocele and sialolithiasis.

Vertical height growth mechanism of hydraulic fractures in laminated shale oil reservoirs based on 3D discrete lattice modeling

Bedding planes are abundant in shale oil reservoirs, but the intrinsic mechanism of fracture-height containment by these weak interfaces remains unclear. To investigate the effects of interface properties, stress conditions, and fracturing fluid viscosity on the vertical propagation of fracture heights in laminated shale oil reservoirs, a three-dimensional hydro-mechanical coupling numerical model was developed. The model is based on the 3D discrete lattice algorithm (DLA), which replaces the balls and contacts in the conventional synthetic rock mass model (SRM) with a lattice consisting of spring-connected nodes, resulting in improved computational efficiency. Additionally, the interaction between hydraulic fractures and bedding planes is automatically computed using a smooth joint model (SJM), without making any assumptions about fracture trajectories or interaction conditions. The results indicate that a higher adhesive strength of the laminated surface promotes hydraulic fracture propagation across the interface. Increasing the friction coefficient of the laminated surface from 0.15 to 0.91 resulted in a twofold increase in the fracture height. Furthermore, as the difference between vertical and horizontal principal stresses increased, the longitudinal extension distance of the fracture height significantly increased, while the activated area of the laminar surface decreased dramatically. Moreover, increasing the viscosity of the fracturing fluid led to a decrease in filtration loss along the laminar surface of the fracture and a rapid increase in net pressure, making the hydraulic fracture more likely to cross the laminar surface directly. Therefore, for heterogeneous shale oil reservoirs, a reverse-sequence fracturing technique has been proposed to enhance the length and height of the fracture. This technique involves using a high-viscosity fracturing fluid to increase the fracture height before the main construction phase, followed by a low-viscosity slickwater fracturing fluid to activate the bedding planes and promote fracture complexity. To validate the numerical modeling results, five sets of laboratory hydraulic fracturing physical simulations were conducted in Jurassic terrestrial shale. The findings revealed that as the vertical stress difference ratio increased from 0.25 to 0.6, the vertical fracture area increased by 1.98 times. Additionally, increasing both the injection displacement and the viscosity of the fracturing fluid aided in fracture height crossing of the laminar facies. These results from numerical simulation and experimental studies offer valuable insights for hydraulic fracturing design in laminated shale oil reservoirs.

Simulation of High-Viscosity Generalized Newtonian Fluid Flows in the Mixing Section of a Screw Extruder Using the Lattice Boltzmann Model.

The mixing quality of polymer melts in the mixing section of a single-screw extruder and an injection molding machine has considerable effects on the properties of the molded products. Therefore, the study of the flow field of polymer melts in the mixing section is of great importance. The lattice Boltzmann method (LBM) exhibits unique advantages in simulating non-Newtonian fluids. Many researchers have used LBM to study the flow of medium- and low-viscosity fluids. In their studies, the Reynolds number of fluid flows is generally moderate. However, polymer melts are typical high-viscosity fluids, and their flow Reynolds number is generally very small. The single-relaxation-time lattice Boltzmann method (SRT-LBM) has been used previously to study the flow field of power law fluids in the mixing section. Herein, the flow field of high-viscosity generalized Newtonian fluids in the mixing section of a single-screw extruder is studied using SRT-LBM, the two-relaxation-time lattice Boltzmann method (TRT-LBM), and the multiple-relaxation-time lattice Boltzmann method (MRT-LBM). Through comparison, TRT-LBM has been found to exhibit obvious advantages regarding stability, calculation accuracy, calculation efficiency, and selection of simulation parameters. The TRT-LBM is more suitable for studying high-viscosity generalized Newtonian fluids than SRT-LBM and MRT-LBM. SRT-LBM has low computational efficiency when simulating high-viscosity generalized Newtonian fluids, and instability is easily caused when the fluid has a yield stress. For MRT-LBM, only by studying the relaxation parameters can its advantages be fully utilized. However, optimizing the accuracy and stability of the MRT-LBM via parameter research and linear stability analysis is difficult. For non-Newtonian fluids, it is difficult to optimize the relaxation parameters to make the MRT-LBM more stable and accurate than the TRT-LBM. It is difficult for the MRT-LBM to realize its potential when simulating high-viscosity generalized Newtonian fluids. In addition, we studied the flow pattern in the cross section of the screw channel and compared it to the results reported in previous studies.

Application of acoustic vibration promotes heat transfer of high-viscosity fluid in a container

The inferior fluidity of high-viscosity liquids hinders their efficacy in heat transfer, resulting in non-uniform heat distribution and occasional overheating, which significantly impairs process and product quality. In this study, we aim to investigate the effect of acoustic vibrations on heat transfer in sealed containers containing high-viscosity fluids by employing computational fluid dynamics (CFD). We established a VOF model and validated it through experiments. Through the collaborative analysis of the velocity field and temperature field, the mechanism of vibration-enhanced heat transfer was revealed. The results of the study indicate that acoustic vibration can enhance convective flow and improve field synergy between the temperature and velocity fields, leading to improved temperature uniformity and heat transfer efficiency. Heat transfer efficiency shows a positive correlation with vibration frequency and amplitude, though no significant correspondence is found with vibration acceleration. Within a certain range, the heat transfer efficiency is more sensitive to the changes in low amplitude or the changes in high frequency. Within a certain range of acceleration, large amplitude with low frequency has a better effect on heat transfer. Finally, we developed a functional relationship between heat transfer efficiency and vibration parameters to predict the heat transfer effect under different parameters, providing suggestions for specific process optimization.

Electroconvective viscous fingering in a single polyelectrolyte fluid on a charge selective surface

When a low-viscosity fluid displaces into a higher-viscosity fluid, the liquid-liquid interface becomes unstable causing finger-like patterns. This viscous fingering instability has been widely observed in nature and engineering systems with two adjoined fluids. Here, we demonstrate a hitherto-unrealizable viscous fingering in a single fluid-solid interface. In a single polyelectrolyte fluid on a charge selective surface, selective ion rejection through the surface initiates i) stepwise ion concentration and viscosity gradient boundaries in the fluid and ii) electroconvective vortices on the surface. As the vortices grow, the viscosity gradient boundary pushes away from the surface, resulting viscous fingering. Comparable to conventional one with two fluids, i) a viscosity ratio (M) governs the onset of this electroconvective viscous fingering, and ii) the boundary properties (finger velocity and rheological effects) - represented by M, electric Rayleigh ({{Ra}}_{E}), Schmidt ({Sc}), and Deborah ({De}) numbers - determine finger shapes (straight v.s. ramified, the onset length of fingering, and relative finger width). With controllable onset and shape, the mechanism of electroconvective viscous fingering offers new possibilities for manipulating ion transport and dendritic instability in electrochemical systems.

Crucial Development Technologies for Volcanic Hydrocarbon Reservoirs: Lessons Learned from Asian Operations

Oil and gas reservoirs in volcanic rocks are a particular type of unconventional reservoir and present unique challenges for exploration and production engineers. To help the oil industry understand volcanic reservoirs and solutions to complex development problems, we reviewed their key engineering technologies as well as their geological characteristics. The distinctive geological characteristics of volcanic hydrocarbon reservoirs are strong heterogeneity, low porosity and permeability, complex fracture systems, etc. The volcanic reservoir rock types in order of hydrocarbon abundance are basalt (38.5%), andesite (15.9%), volcaniclastic (12.1%), and rhyolite (11.5%). The porosity ranges from 0.1 to 70%, and permeability ranges from 0.0007 to 762 md. In some commercially developed volcanic reservoirs of China, the average porosity is 7.7–13%; the average permeability is 0.41–3.4 md. Engineers have applied a variety of adapted technologies to produce volcanic reservoir economically. Horizontal wells can increase production and reserves by 4–6 times those of vertical wells, and longer wells are preferred. Specialized hydraulic fracturing techniques are suggested, including small or mixed proppant size, second HF treatment after proppant slugging, high-viscosity frac fluid with high-temperature resistance, special fluid loss reducer, high pump pressure, Extreme Overbalance Perforating, limited-entry fracturing, matrix acidizing, etc. Water control measures include producing below critical rates, partial perforation or penetration, controlling hydraulic fracture height, using horizontal wells, implementing complete cementing job, etc. Well productivity evaluation should be conducted to understand well performance and appropriately allocate production rates among wells, using the modified AOF method and other productivity prediction models considering breakdown fracture gradient, gas slippage effect, non-Darcy effect, etc. Well sites need to be selected based on recognizing profitable lithologies, lithofacies, high porosity and permeability, relatively developed fracture systems, thick net pay zones, etc. The critical questions for the industry are how to enhance volcanic reservoir recovery with more efficient and economic hydraulic fracturing and water control techniques. This is one of the first papers systematically summarizing the engineering technologies and unique solutions to develop volcanic reservoirs. Further and more complete reviews can be carried out in the future, and more novel and effective techniques can be explored and tested in the field.

Effects of Pipe Rotation on the Performance of Fibrous Water-Based Polymeric Fluids in Horizontal Well Cleanout

Summary The deposition of rock cuttings is a problem commonly faced during drilling, completion, and intervention operations. Using polymer-based fluids is a common technique to improve horizontal downhole cleaning. However, these fluids cannot always guarantee an efficient wellbore cleanout. One way to enhance cleanout efficiency is by rotating the drillpipe to mitigate the settling of solids and facilitate their removal. However, drillstring rotation often increases equivalent circulating density (ECD). Therefore, in this study, we explore how the impact of rotation on hole cleaning can be synergized by using fibrous water-based polymeric fluids to perform cleanout at reduced rotational speeds with limited effect on ECD. The flow loop used for this study consists of a 48-ft long eccentric annular (5×2.375 in.) test section. Each experiment began by forming a stationary bed of natural sand (an average diameter of 1.2 mm) in the test section. High-viscosity and low-viscosity polymer-based suspensions with and without fibers were used. The drillpipe rotation speed was varied from 0 to 150 rev/min. In each experiment, the flow rate was increased from 35 to 195 gal/min stepwise. The bed perimeter was measured at equilibrium condition for every test flow rate until a complete bed cleanout was achieved. In addition, the friction pressure loss was measured. Rotational viscometers were also used to measure fluid rheology before and after each test. Fiber particles improve the carrying capacity of the fluid by reducing solid settling and minimizing the redeposition of particles. The results demonstrate the effectiveness of fiber in synergizing pipe rotation effects on hole cleanout performance in horizontal wellbores. Fiber’s impact is more pronounced when used with low-viscosity fluid. The cleanout performance of the low-viscosity fluid is amplified significantly with rotation, almost entirely cleaning the bed at 75 gal/min and a rotational speed of 50 rev/min, compared with more than 195 gal/min without rotation. Even more improvement could be achieved by adding a small amount of fiber (0.04wt%). In addition, the fiber improved the cleanout performance of the high-viscosity fluid. The enhancement, however, was not as noticeable as with the low-viscosity fluid. In general, rotation combined with low-viscosity fibrous fluid exhibits the best cleaning performance. This is because rotating the pipe resuspends the settled solids, which are then easily carried by fibrous fluid that has high solids carrying capacity.

Enhancing hydraulic fracturing for in-situ remediation in low-permeability soils: A comprehensive investigation of fracture propagation

Enhancing the complexity of the hydraulic fractures to provide a wide channel for the injection of the agent is crucial for remediating low-permeability contaminated sites. This study involved a physical simulation experiment of large-scale true triaxial hydraulic fracturing in undisturbed soil, as well as field fracturing tests, to investigate fracture initiation mechanisms and the influence of different factors on fracture propagation. The study revealed a unique failure mode for low-permeability soils characterized by impact splitting, involving simultaneous tensile and shear failure. Three typical fracture propagation patterns emerged: (1) horizontal fracture, (2) parallel fracture, and (3) complex fracture. Silty clay predominantly exhibited horizontal fractures, while mucky clay facilitated the formation of complex fractures dominated by multiple transverse fractures. As the vertical stress difference coefficient increased from 1.0 to 1.5, the pressure on the fracture surface enhanced the connection between hydraulic fractures and natural fractures. Hydraulic fracturing in low-permeability soils necessitated large displacements and high-viscosity fracturing fluids to sustain fracture propagation. The field fracturing test results underscored that soil type and in-situ stress were the primary factors governing hydraulic fracture initiation and propagation. Identifying the optimal fracturing location was critical for achieving the maximum stimulated formation volume.

Continuous flow microwave processing of liquid whole egg: Pasteurization and functional characteristics evaluation

The objective of this study was to assess the impact of continuous flow microwave processing on the pasteurization efficiency and quality attributes of liquid whole egg (LWE). The heating section was accomplished using microwave, while the holding section utilized a water bath, and the process parameters were determined by a developed numerical model. The inactivation kinetics of Escherichia coli, Staphylococcus aureus, and Salmonella Enteritidis were evaluated at three temperatures (56, 60 and 64 °C) and two power-density (8 and 16 W/mL with different flow rates). A 5-log10 reduction was achieved and the Weibull model fitting the survival data well, which contributed to the optimization of microwave pasteurization process. Additionally, microwave promoted the transitions of secondary structures from β-sheet to α-helix and stabilised the system by enhancing the zeta potential value, further improving the emulsifying and foaming properties. The major proteins in LWE were not found to undergo degradation according to the results obtained from SDS-PAGE analysis. The results of this study suggested that continuous flow microwave pasteurization of LWE exhibits potential as a viable alternative to conventional pasteurization methods. Industrial relevanceThe adoption of high-efficiency physical processing methods is imperative for the sustainable and low-carbon advancement of the food industry. This study confirmed the feasibility of continuous flow microwave pasteurization as an alternative to conventional methods for liquid whole egg, addressing key limitations encountered in traditional pasteurization approaches, and the findings offer practical insights for industrial-scale production. Additionally, the development and application of a continuous flow microwave heating system for pasteurizing liquid whole egg provide valuable knowledge for the utilization of microwave treatment in processing high-viscosity and heat-sensitive fluid foods.

Migration and sedimentation of proppant and its influencing factors in a visual plate fracture model

Hydraulic fracturing technology is the main method used to form high-conductivity fracture networks in unconventional oil and gas reservoirs, and the effective filling of quartz sand proppant in the fracture network is key to its successful implementation. Conventional experiments on the evaluation of sand carrying migration are mainly based on the migration and sedimentation law of a single-mesh proppant in the main fracture; the results obtained are inconsistent with the field observations. To improve our understanding of the migration and sedimentation law of the proppant in the main and branch fractures, in this study, the influences of injection time, injection rate, fracturing fluid viscosity, and proppant combination type on the migration and sedimentation law of a proppant in single and branch fractures were analyzed based on the injection parameters of the sand-carrying fracturing fluid obtained using a similarity criterion through a visual large-scale parallel-plate fracture model system built indoors. The results showed that the rapid accumulation stage of the proppant in the fracture is during the injection time of 5–10 min; the injection rate affected the accumulation area and height of the proppant to a certain extent but had little effect on the final sand dike morphology. A low viscosity of the fracturing fluid was not conducive to the sedimentation of the proppant in the branch fractures; an excessively high fracturing fluid viscosity was not conducive to the sedimentation of the proppant in both the main and branch fractures. When the fracture morphology is single, the viscosity of the fracturing fluid is recommended to be between 30 and 60 mPa·s. When the fracture morphology is complex, the recommended value is between 40 and 50 mPa s. Taking the migration and sedimentation laws of the proppant in the main fracture as an example, the flow of fracturing fluid in the fracture after the formation of a stable sand dike could be divided into five regions: ① inlet scour zone; ② buffer zone; ③ sand dike stable transition zone; ④ sand dike stability zone; and ⑤ outlet scour zone. The higher the large mesh proppant ratio used in the fracturing fluid, the lower the total area ratio of the corresponding sand dike; however, the proppant sedimentation ratio in the branch fracture increases. This study enriches and improves the relevant theoretical research on the migration and sedimentation of proppants and has a certain effect on improving the success rate of the hydraulic fracturing technology applied to unconventional oil and gas reservoirs.

Adult rhinoceros beetles use a sweeping pattern to ingest high-viscosity fluid

More than half of all insect species utilize various natural liquids as primary diet. The concentrated liquids with energy-dense nutrition can provide highly favorable rewards, however, their high-viscosity poses challenges to the insect for ingesting. Here we show that rhinoceros beetles, Trypoxylus dichotomus (Coleoptera: Scarabaeidae), are capable of ingesting sugar solutions with viscosities spanning four orders of magnitude, exhibiting extraordinary adaptability to diverse natural liquid sources. We discovered a previously unidentified maxillae-sweeping motion that beetles preferentially adopt to consume highly viscous liquids, achieving a higher feeding rate than the more common direct sucking. By utilizing morphological characterizations, flow visualization, and fluid–structure coupling simulation, we revealed the underlying mechanisms of how this maxillary movement facilitates the transportation of viscous liquid. Our findings not only shed light on the multi-functionality of beetle mouthparts but also provide insights into the adaptability of generalized mouthparts to a broad range of fluid sources.

Ink Fluidic Behaviors during R2R Slot Die Coating on Quality Thin Film Formation

High throughput slot die coating is a desired fabrication method for flexible display, solar cell, Li-ion battery pack, intelligent package and wearable electronics. In this study, the stability of the thin film formation by slot die coating is investigated through theoretical, experimental and numerical studies with the combined effects of the fluid and substrate surface characteristics. The theoretical model based on the viscous capillary theory reveals fluid upstream and downstream distribution patterns and associated parameters that descript the coating layer stability. A 3D model based on the volume of fluid method (VOF) is developed to illustrate the coating process affecting the coating quality by the substrate velocity and flow rate. The numerical and experimental results agree that higher viscosity fluid is more prone to trap air bubbles and/or to create de-wetting areas while as the lower viscosity fluid were responsible for upstream liquid dripping. Boundary by the fluid, substrate, and operating parameters, our numerical study has developed the coating operation window to minimize or eliminate coating defects which has been confirmed by the experiments. These study results could lead high yield coating processes and efficiency in large area functional coating production.

Uniform Acid Cleaning Technology and Its Application in Horizontal Wells with Open Hole Screen Tube

After the completion of the open hole sieve tube in a horizontal well, it is necessary to replace the slurry and put it into production. Generally, circulating acid outside the tube cannot fully remove mud pollution. The acidification process needs to fully consider the heel effect of horizontal wells. Based on the horizontal pipe flow model and the characteristics of foam diversion, a mathematical model of acid washing suitable for open hole screen horizontal wells is established. Analysis suggests that lower flow rates and higher fluid viscosity during the acid washing process are more conducive to the uniform entry of the plugging solution into the formation. We have designed a uniform liquid mixing equipment with a flow blocking mechanism, and improved the acid washing construction process to achieve negative pressure reverse discharge of acid solution. This process can achieve uniform entry of the unblocking fluid into the formation after passing through the screen gap, and remove the blockage of the mud layer inside and outside the near screen tube. The horizontal wells using this process have a 30% increase in production capacity compared to oil wells in the same block, and the high yield validity period has been extended by 680 days.

Acoustic wave propagation in a porous medium saturated with a Kelvin–Voigt non-Newtonian fluid

SUMMARYWave propagation in anelastic rocks is a relevant scientific topic in basic research with applications in exploration geophysics. The classical Biot theory laid the foundation for wave propagation in porous media composed of a solid frame and a saturating fluid, whose constitutive relations are linear. However, reservoir rocks may have a high-viscosity fluid, which exhibits a non-Newtonian (nN) behaviour. We develop a poroelasticity theory, where the fluid stress-strain relation is described with a Kelvin–Voigt mechanical model, thus incorporating viscoelasticity. First, we obtain the differential equations from first principles by defining the strain and kinetic energies and the dissipation function. We perform a plane-wave analysis to obtain the wave velocity and attenuation. The validity of the theory is demonstrated with three examples, namely, considering a porous solid saturated with a nN pore fluid, a nN fluid containing solid inclusions and a pure nN fluid. The analysis shows that the fluid may cause a negative velocity dispersion of the fast P(S)-wave velocities, that is velocity decreases with frequency. In acoustics, velocity increases with frequency (anomalous dispersion in optics). Furthermore, the fluid viscoelasticity has not a relevant effect on the wave responses observed in conventional field and laboratory tests. A comparison with previous theories supports the validity of the theory, which is useful to analyse wave propagation in a porous medium saturated with a fluid of high viscosity.