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DDWC (Directional Drilling with Casing) is an effective wellbore construction technique, particularly suitable for soft marine formations. In DDWC, the casing replaces the drill pipe for sliding drilling operations, and the passability of the drill string through the casing has become one of the primary challenges in applying DDWC. This study uses ANSYS Workbench to simulate the strain and bending behavior of the casing under various geological conditions. Simulations were conducted for different wellbore trajectories, casing specifications, and materials to evaluate the feasibility of the drill string passing through the casing under different conditions. The results show that, when the dogleg severity reaches 18°/30 m and the casing's inner diameter is 315 mm, the maximum radial strain of the casing is 4.2 mm, which cannot guarantee the successful passage of a drill string assembly with a 311 mm outer diameter. For other casing specifications, with a minimum inner diameter of 317 mm, the drill string can pass through under the maximum dogleg severity. Additionally, since the elastic modulus and Poisson's ratio of the casing materials are identical, the strain behavior is consistent across different materials, meaning that the material does not affect the passability of the casing. Moreover, the study optimized the selection of casing specifications and materials. From the perspective of ensuring drill string passability and resource conservation, a casing with an inner diameter of 319.4 mm was chosen. To ensure the longevity of the casing and the stability of the wellbore, N80 steel was selected as the material. A sensitivity analysis was conducted on the factors affecting casing strain, and the results aligned with the simulation findings, showing that wellbore trajectory and casing specifications have a significant impact on casing strain. Verifying the passability of the drill string through the casing is critical for the development and application of DDWC technology. [ABSTRACT FROM AUTHOR]

Copyright of CT Theory & Applications is the property of Editorial Department of CT Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Compressed air energy storage (CAES) technology is a large-scale, flexible and low carbon energy storage technology that utilizes compressed air for energy storage. All injectors and producers in the Yunying energy storage are faced with well cementing difficulties such as low formation temperature, large hole diameter, potential losses of cement slurry during well cementing, frequent alternation between injection and production, as well as strict requirements for long-term isolation of the wellbore etc. To solve these difficulties, well cementing techniques suitable for the CASE wells drilled in Yingcheng, Hubei Province are studied. A low-temperature salt-resistant tough cement slurry suitable for cementing the injectors and the producers drilled for the salt cavern energy storage is developed based on the close packing design theory and the induction of crystal phase structure design method. A set of well cementing technique based on this new cement slurry is developed. The density of the cement slurry can be adjusted between 1.88 g/cm3 and 1.93 g/cm³ . The thickening time of the cement slurry is easy to be changed to meet the operation requirements. The cement slurry has no density difference between the top and the bottom, zero free water and API filter loss of less than or equal to 50 mL. Contamination by salt to semi-saturation is of no influence to the performance of the cement slurry. The 7 d elastic modulus is less than 6.13 GPa. At temperatures lower than 30 ℃, the strength of the cement slurry can develop in less than 10 h. The 24 h compressive strength of the set cement is greater than 14 MPa. This cement slurry and the well cementing techniques have been used in the cementing of the surface casing and the production casing of the injectors and the producers drilled for the CAES in the Yunying basin in Hubei. The cementing job is 100% qualified and 95% of which is excellent. [ABSTRACT FROM AUTHOR]

Titanium alloys have been widely used for drill pipes in complex structural wells and ultra-deep wells because they can provide great benefits in cost and operation in drilling systems due to their excellent properties such as high strength, low density, exceptional corrosion resistance and inherent flexibility. However, their wear behaviors during drilling have not been well understood by the communities. In this work, the effect of the impact force on the wear performance of titanium alloy drill pipes against steel casings was investigated through using a modified wet impact-sliding pin-on-disk test system, in which ZSA-3 titanium alloy was used for the pins and J55 steel was for the disks. The tests were conducted under simulated drilling mud conditions. As the impact force increases, the coefficient of friction tends to become stable and fluctuates slightly, and thus the wear rate of the tribo-pairs decreases gradually. The wear mechanism of J55 steel disks presents a transition from plastic deformation to plastic deformation accompanied by adhesive wear, while that of the titanium alloy pins changes from the plowing effect with adhesive wear to plastic deformation and adhesive wear. In addition, complex oxides will be formed on the surfaces of the tribo-pairs due to the oxidation of Ti and Fe during the wear process. The present results could provide as a fundamental guide for the drilling engineers in related industries for reducing casing wear in the drilling environment. [ABSTRACT FROM AUTHOR]

This paper presents a fully coupled solution in the time-domain, using the finite-differences method to the system of equations that model the dynamic behavior of the riser, blow-out preventer (BOP), and casing strings, when connected for well drilling/completion--the model is suitable to evaluate wellhead fatigue, even when the amplitude of oscillation and accelerations of the BOP are high. Sensibility analysis is used to show the effect of changing the Riser Top Tension to the resulting maximum values of wellhead bending moment and casing stress ranges. For the case where the rig is oscillating around a fixed position and there is no current, using a regular wave, the results show that there are some wave periods for which an increase in the Riser Top Tension reduces the maximum wellhead bending moment and the max casing stress range, therefore increasing fatigue life of the casing and wellhead. The effects of varying the weight of the BOP and soil parameters and the effect of the phase difference between the wave and first-order vessel motion are analyzed. The proposed solution can also be used to perform riser and casing analysis during drift-off/drive-off. [ABSTRACT FROM AUTHOR]

Morphometry of pinna may change following ear surgeries. This study gives information about postoperative changes following ear surgeries. This study aims to measure the variation of ear morphology following surgery and to correlate the type of surgery with post-operative variations. Eighty patients with Chronic Otitis Media(COM) undergoing surgery by post aural approach were grouped into Modified Radical Mastoidectomy (MRM), Cortical Mastoidectomy + Tympanoplasty (CM + TM) and Tympanoplasty groups(TM). The MRM, CM + TM and TM groups had 14, 46 and 20 participants respectively. Various morphometric measurements were taken pre and post operatively. In all groups, the mean Concho-Mastoid Angle (CMA) was increased post operatively, with increase of 11.1 degrees in MRM (p value-0.002), 8.9 degrees in CM + TM (p value-0.000) and 4.8 degrees (p value- 0.657) in TM group. Similarly, the Cepahlo-auricular distances (D1 and D2) showed statistically significant changes in MRM and CM + TM groups (p value < 0.05). Mean CMA of MRM group compared with other groups did not show any statistically significant difference. However, when the CMA of CM + TM group was compared with TM group showed significant difference of 14.53 degree (p value 0.002). Similarly, the D1 and D2 showed statistically significant changes between the CM + TM and TM groups (p value 0.005 and 0.000 respectively). Prominence of pinna following ear surgery is a not a myth. It happens mostly in cases requiring drilling of the mastoid, rather than Tympanoplasty alone. This needs to be explained to the patient beforehand to prevent any confusion post operatively. [ABSTRACT FROM AUTHOR]

The exploration and development of new hydrocarbon deposits face increasing challenges, primarily driven by the shift away from hydrocarbons towards renewable energy sources like shallow geothermal deposits, wind farms, and photovoltaics. This shift necessitates finding solutions that minimize environmental impact and enable increased energy extraction from existing or decommissioned fields and wells. This paper explores the possibility of excavating from potentially depleted fields, where a significant portion (up to 85%) of the reservoir's resources remain unrecoverable due to low reservoir energy. To address this, secondary and tertiary exploitation methods are proposed involving the supply of external energy to increase the pressure in the reservoir layer, thereby enhancing resource exploitation. One of the suggested tertiary methods involves reaming the deposit with multiple small-diameter radial holes using a hydraulic drilling nozzle. The entire process comprises several key components, including the coiled tubing unit (CTU), high-pressure flexible hose, window drilling kit for casing pipe, kit for positioning the exit of the hydraulic drilling head from the casing pipe, anchor, and hydraulic drilling head attached to the end of the high-pressure flexible hose. This method aims to increase the contact between the reservoir layer and the wellbore, potentially leading to an increase in or initiation of exploitation in certain deposit scenarios. The described method presents an environmentally friendly approach, eliminating the need for drilling new boreholes and offering cost-effective access to resources in decommissioned deposits with insufficient reservoir energy for self-exploitation. The applicability of this method to extract methane from coalbed seams is also mentioned in this article. In a separate article, the authors detail the design of a hydraulic drilling nozzle specifically for reaming the reservoir layer. [ABSTRACT FROM AUTHOR]

Dual-gradient drilling technology is difficult to detect and deal with well kick, which may cause safety problems such as well control. Once a well kick occurs, the pressure in the narrow annulus increases instantaneously, so it is particularly important to clarify the transmission law of pressure wave. Taking the pressure fluctuation in the annulus of double gradient drilling as an example, considering the boundary between the inner wall of the casing annulus and the outer wall of the drill string, the fluid resistance, the flow field distribution and the multiphase flow, this paper deduces and establishes the multiphase flow pressure wave velocity model in the annulus, and compares the calculation results with the pressure wave velocity model in the circular pipe. The research shows that when the casing and drill string are in the static condition with small roughness and little difference between them, the shear stress on the inner wall of the annulus and the outer wall of the drill string can be treated as equal, and the derivation of the annulus pressure wave velocity model can be simplified. The pressure wave velocity of multiphase flow in annulus is related to casing size, drill string size and multiphase fluid properties. Among them, the gas content is the main influencing factor. With the increase of the gas content, the pressure wave velocity decreases, but the decreasing range will gradually decrease. When the solid content is small, it has little effect on the pressure wave velocity. [ABSTRACT FROM AUTHOR]

The object of research in this study is viscoelastic systems used as spacer systems in well casing during drilling. Polymer network-metal ion systems display distinctive properties, facilitating effective well coverage through their normal stresses. The primary problem addressed in this research was optimizing viscoelastic system composition for well casing. Researchers sought the ideal sodium dichromate concentration to maximize viscosity in polyacrylamide-based spacer fluids. This optimization is crucial for enhancing casing cementing quality, especially in challenging geological conditions. Utilizing a precise HAAKE MARS III rheometer, various tests, including shear, oscillatory, frequency, creep, and recovery tests, were performed to assess viscoelastic system rheology. Obtained results of optimal deformation interval for a solution with sodium bichromate is 40 Pa and aluminum sulfate, the yield strength was equal to 110 Pa. This research optimized cross-linker concentration, increasing spacer system viscosity. This enhancement improves well cementing efficiency and allows for operation in challenging geological conditions. The precise rheometer unveiled previously unexplored rheological characteristics. The optimized viscoelastic spacer fluid is invaluable in well casing, especially in challenging geological settings. This research guides the design of process fluids, enhancing casing cementing quality, and improving drilling efficiency and safety. Engineers and researchers can leverage the rheological data for informed decisions and better field performance. [ABSTRACT FROM AUTHOR]

The geometric form and mechanical state of flexible short joints and milling tools directly affect the efficiency of casing side drilling window opening and the shape of side drilling window. Based on the principle of casing window drilling technology, analyze the force, vibration, and bending status of the flexible short joints and milling tools, design a "five factor and four level" orthogonal experiment, obtain the optimal level parameters of the tool structure and operation, and study the influence of different optimal level parameters on the Mises stress, milling cone cutting force, and lateral force of the flexible short joint. The results show that the drilling pressure, short pitch diameter to thickness ratio, and short pitch length have a significant impact on the mechanical properties of the tool, while the impact of rotational speed and casing type is relatively small. The time required for casing window opening operation in a certain well has been reduced, and the overall window opening efficiency has increased by 30. 6 % compared to the average level of other conventional window opening wells in the same block. This method can effectively improve the efficiency and lifespan of the tool, and the optimal parameter combination provides a reference for the optimization of window opening tool models and parameters under different working conditions. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate estimates of Unconfined Compressive Strength (UCS) are essential for a range of subsurface applications, including drilling wells for subsurface fluid extraction or injection. However, measuring UCS of subsurface rock samples through laboratory-based uniaxial and triaxial testing is time consuming, expensive, and potentially subject to individual sample variance. P-wave velocity logs are routinely obtained in petroleum basins and are commonly used to estimate UCS using empirically-derived correlations. In this study we analysed P-wave velocity data from 43 wells in the Cooper Basin, Australia and created mean ranges of expected UCS through the Tirrawarra, Toolachee, Patchawarra, Murteree Shale and Epsilon formations, using literature-derived P-wave velocity-UCS correlations, and also estimated UCS based on selected available laboratory-determined P-wave velocity measurements. These two suites of P-wave velocity-derived estimates of UCS are then compared to available results from laboratory uniaxial testing of core samples. Our analysis indicates that P-wave velocities, and subsequent derived estimates of UCS from P-wave wireline logs, are typically lower than those from laboratory-analysed samples. This may reflect a sampling bias towards the selection of strong rocks for laboratory UCS testing or lower estimates of UCS due to wellbore damage and pore space content (air or liquids) from P-wave log derived velocities. However, the laboratory-derived P-wave velocities generally agree with laboratory-derived UCS data from the Patchawarra, Murteree Shale and Epsilon formations when using published empirical velocity-strength correlations. A retrospective case study presents the impacts of different UCS estimates on mud weight required to produce observed borehole breakouts in the Epsilon Formation. Breakouts were observed 90 degrees to the orientation of SHmax (117° N) with a mean width of 51°, the breakouts were produced during drilling using a 9.7 ppg mud weight. The back-calculated estimate of UCS from the observed breakout widths at 9.7 ppg is 154 MPa. This sits between the UCS estimate of 171 MPa from uniaxial testing and 145 MPa from the mean of laboratory sample-derived P-wave velocities. Estimates of UCS from empirical correlations based solely on p-wave log-derived are far lower and vary between 87.3 and 114.4 MPa. [ABSTRACT FROM AUTHOR]

Neural networks have been widely applied in system dynamics modeling. One particular type of networks, hybrid neural networks, combines a neural network model with a physical model, which can increase rate of convergence in training. However, most existing hybrid neural network methods require an explicit physical model constructed, which sometimes might not be feasible in practice or could weaken the capability of capturing complex and hidden physical phenomena. In this paper, we propose a novel approach to construct a hybrid neural network. The new method incorporates the physical information to the structure of network construction, but does not need an explicit physical model constructed. The method is then applied to modeling of bit-rock interaction in the down-hole drilling system as a case study, to demonstrate its effectiveness in modeling complex process and efficiency of convergence in training. [ABSTRACT FROM AUTHOR]

A dam foundation structure is usually strengthened by grouting, which begins with grout hole drilling. This paper aims to examine a comparison between conventional rotary and rotary-percussion drilling techniques in a drilling case study of the Tugu Dam Project, from the perspective of time, cost, and quality comprehensively. Primary data was obtained from the field investigation and interviews. Secondary data was gathered from available project documents of the PT Wijaya Karya-APTA KSO Project Contractor. The findings have highlighted that the implementation of the rotary-percussion technique for grout hole drilling is better than conventional rotary drilling. There are 16 days of time-saving and 3.84% cost-savings for the rotarypercussion technique, as a result of faster rate of penetration. The quality of grouting work using the rotary-percussion drilling technique tends to be of better quality, although there is a shortcoming due to the limited drilling depth of only 5m particularly. [ABSTRACT FROM AUTHOR]

Comparative thanatology includes the scientific study of death in non-human animals, which involves emotional, social, and exploratory responses of individuals and groups towards corpses. Stillborn babies and dead infants often elicit maternal and alloparental care that can persist for days, weeks, or even months, especially in primates. After this period, cannibalistic acts can occur not only by groupmates but also by the mother. Such cannibalism has been reported both in captive and wild primate groups, suggesting that the phenomenon is evolutionary adaptive. Here, we report a case in drills (Mandrillus leucophaeus), a largely unstudied monkey species. We collected data from the birth to the death of the infant on maternal and alloparental care towards the newborn across three phases: pre-mortem, post-mortem, and post-mortem cannibalism. The mother maintained high levels of grooming after the infant's death. Both the mother and other group members interacted with the dead baby by trying to engage its gaze. Two days after the death, the mother started to eat the corpse until it was almost completely consumed; there was no sharing with other group members. Although we cannot draw firm conclusions about potential benefits of the mother's behavior, this observation on drills adds a piece to the puzzle of thanatological behaviors and cannibalism in primates. [ABSTRACT FROM AUTHOR]

The drilling process using a twist drill tool has high interest in industry, especially in plate metal work. Consequently, during the first penetration through the metal, the sudden stop of the tool at the cutting end or the pulling of the tool from the work piece in the finish can cause crystal nodes to form. This generates torsional torque between the tool and the work piece, which causes torsional shear stress and strain to be translated to the tool root, potentially leading to failure or a dislocated catch region, resulting in hole deformation. So, this paper focuses on how to deal with the increasing stress and strain caused by a sudden stop by using a lubricant liquid that directs flow when a strain gauge attached to the cutting tool detects increasing tool strain. The experimental strain readings in dry conditions and with lubricant liquid are recorded. The Timoshenko equations are used to improve the translation of stress and strain to the tool root and to simulate a torsional case in a cutting tool subjected to torsional torque with the same experimental value (576, 220, 130, 95 N.m.). The results are approximately convergence with a R2 correction factor of 0.9. [ABSTRACT FROM AUTHOR]

As one of the most important parts of deep space exploration missions, the sampling technologies of extraterrestrial celestial bodies (ECBs) have attracted the attention and interest of many researchers. As a relatively efficient and convenient sampling technique, drill samplers have been applied in different ECBs exploration missions. Different from the previous drill apparatus, this paper introduces a novel automatic assisted drill system (AADS), which is used to sample the deep layer regolith of ECBs. This drilling system can sample the deep regolith layer under manual assistance or unmanned automatic operation mode. The sampler has improved and designed a segmented detachable coring pipe, drilling pipe and casing pipe. It can largely maintain the layer information in the depth direction of the ECBs regolith and can also automatically change the drill sampling process through the driller change system to improve the sampling efficiency. Finally, an automatic test apparatus was designed, and an experimental platform was established to conduct a drill sampling test for the AADS sampler. The experimental results show that the AADS sampling system can successfully obtain at least 2.4 m depth and 1.1 kg weight simulated regolith samples. • The AADS design details are provided. • The AADS sampling strategy are analyzed. • An automatic test apparatus and experimental platform are introduced. • Preliminary filed test results are presented. [ABSTRACT FROM AUTHOR]

The existing research identifies that cross-organizational collaboration is important in the enhancement of emergency management. However, little effort has been made to empirically examine how collaboration contributes to emergency performance. Within this field lies a theoretical controversy that institutional arrangement and dynamic capability compete with each other to enhance emergency collaboration. Numerous studies find that a contingency plan, as a form of institutional arrangement, is necessary for ensuring collaboration in a planned and legitimate manner. Conversely, research also suggests that absorptive capacity, as an important dynamic capability for organizations to adapt to changing environments, is beneficial to the improvement of emergency collaboration. The current study contributes to the understanding of the influence of collaboration on emergency performance by (1) investigating the relationship between collaboration networks and performance, and (2) examining the mediating roles of the contingency plan and absorptive capacity in this relationship. Employing structural equation modeling with data from 110 cases of emergency drills in Shanghai, results suggest that collaboration networks have a positive association with emergency performance, which is simultaneously mediated by contingency plan and absorptive capacity, and further demonstrate that absorptive capacity exerts a stronger effect than contingency plan. Overall, the findings point to a need to dissolve the nuanced contradiction between the institutions and dynamic capability and weigh the two approaches when implementing emergency collaboration across organizations. [ABSTRACT FROM AUTHOR]

A snake-bone flexible drill pipe was designed based on bionics to relieve the overlarge deflecting curvature radius of the sidetrack horizontal well. Specifically, flexible design is carried out for coiled tubing in combination with morphology and mechanism bionics. The ball head+external casing+torque pin structure was used to decompose the drill pipe, and the torque pin was used to transfer torque. Each section can reach a torsion angle of 4.1°, which can alleviate the buckling of the drill pipe in the casing pipe. A maximum bending angle of 5.12° can be generated between sections, and the deflection curvature radius is shortened to 1.8 m. To overcome the directional uncertainty between flexible drill pipe sections of small curvature radius during dispersion, a highly flexible pipe was added at the angle in the flexible drill pipe, which guaranteed a high discharging rate. Based on the multi-body dynamics finite element analysis software ADAMS and the statics simulation software ANSYS, the multi-body linkage dynamics and statics simulation analysis were carried out for the flexible drill pipe as a whole, which confirmed the effectiveness of the described deflecting method. Field experiments were carried out in Well PU 2-365, and the borehole trajectory was calculated based on the data derived from the inclinometer. The deflection section curvature radius could reach 1.8 m, which completed the design expectation. [ABSTRACT FROM AUTHOR]

By analyzing the residual rate of drilling fluids on the surfaces of casing strings in ultra-deep wells, it was ascertained that temperature is the main factor affecting the residue of drilling fluids on the surfaces of the drilling strings. In high temperature ultradeep wells, oil-based drilling fluids are apt to lose their emulsion stability and become demulsified, turning from hydrophobic to hydrophilic. Water-based drilling fluids, on the other hand, are dewatered at elevated temperatures, turning from hydrophilic to hydrophobic. Using XRD, element analysis, SARA and FTIR methods, the components of the residues of a water-based drilling fluid and an oil-based drilling fluid commonly used were analyzed. The main components of the residues were known to be cellulose and the mixture of clay and barite particles coated with sulfonated phenolic resin for the water based drilling fluid, and asphalt and barite coated with oleic acid amide for the oil-based drilling fluid. The adsorption effect of the macromolecules in a drilling fluid on the surfaces of casing strings was calculated using molecular dynamics simulation based on the analyses of the residues in the drilling fluids. The calculation showed that the binding energy between porphyrin (the major component of asphalt) and the casing wall is - 54.18 kcal/mol, the binding energy between oleic acid and the casing wall is -19.72 kcal/mol, the binding energy between cellulose and the casing wall is -19.09 kcal/mol, and the binding energy between sulfonated phenolic resin and the casing wall is -93.19 kcal/mol, respectively. These results have proved that compared with oil-based muds, the organic components in a water-based are much more adhesive at elevated temperatures. This analysis of the casing contamination by drilling fluids will provide theoretical guidance to the cleansing of casing strings in the future. [ABSTRACT FROM AUTHOR]

With the development of different segments within the drilling technology in the last three decades, well drilling has become possible in harsh downhole conditions. The vertical well provides access to oil and gas reserves located at a certain depth directly below the wellsite, and a large number of vertical wells are required for the exploitation of hydrocarbons from spatially expanded deposits. However, the borehole can deviate from the vertical well, which means that the target zone can be reached by a horizontal directional well. With this type of well, especially in the case of drilling an extended-reach well (ERW), the length of the wellbore in contact with the reservoir and/or several separate reservoirs is significantly increased, therefore, it is a much better option for the later production phase. Unfortunately, the application of extended-reach drilling (ERD technology), with all of its advantages, can cause different drilling problems mostly related to the increased torque, drag, hole cleaning and equivalent circulation density (ECD), as well as to an increase in the well price. Overcoming these problems requires continuous operational change to enable operators to address downhole challenges. Today, the longest well reaches 15,240 m (50,000 ft), which raises the question of the technological and economic feasibility of this type of drilling project, especially with the lower oil price on the energy market. This paper provides a comprehensive overview of extended-reach drilling technology, discusses the main problems and analyzes current achievements. [ABSTRACT FROM AUTHOR]

The aim of this study is to examine the deformation characteristics of UPVC pipes with a diameter of 0.40 near the staged drilling trench by adopting a numerical model (PLAXIS 3D) by using standard backfill and same natural soil surrounding the pipe. Two cases of tube loading, loading and unloading (empty) have been examined using three tube surface points Crown Center (CC), left middle (CL) and Central Tip (CT) and in two cases of backfill. Then the deformations of the tubes have been compared at three points and additionally the deformations of the loaded and empty tubes have been examined in two cases of backfill near the trench. The results have showed that the pipe deformation is up by 63% of the final vertical deformation in the failure stage for three examined points in the case of standard backfill and drilling depth equal to 1/3 HP, while the rate of change in vertical deformation has been about 80% in the case of equal drilling depth Hp. As for the contrast of the vertical distortion, the maximum contrast has reached about 20% at the CC point, about 11% at the CL point and the lowest percentage has been on CT. For standard backfill, the digging depth is greater than or equal to Hp, the horizontal deformation is approximately 100% greater than the horizontal deformation for the CL and CT points, and by more than 150% for the CC point. Comparison of these points in the failure phase has showed that the difference between the maximum and the minimum horizontal deformation along the tube section has changed little by 8% at the CT point and about 40% and 25% at the CC and CT points, respectively. The comparison of two cases of tube deformation backfill in the failure stage has also showed that it had vertical and horizontal deformations about seven and five times respectively in standard backfill compared to natural soil backfill. [ABSTRACT FROM AUTHOR]

Watch a video of this article. [ABSTRACT FROM AUTHOR]

The purpose of the software development presented in the article is to obtain detailed information about the surface of the walls in wells necessary for more efficient and safe drilling and casing of the wellbore. The developed software of the automated system "LogPWin" allows obtaining a clear idea of the mine itself, as well as reducing the time spent on processing and analyzing the model obtained during the logging process. A software product developed as a result of the work provides visualization of data coming from an acoustic profiler, giving a visual and informative idea of the object of study. The program gives detailed information about the surface of the mine's walls through 3D modeling. It possesses the possibility of rotating and scaling the object; there is also a color palette that can be changed depending on the incoming data. The program can be applied in the oil and gas industry and mining, as well as when drilling wells for other purposes. The program interface is quite clear and simple. The structure of the program is made in such a way that it allows obtaining data for building an object not only in real time, but also through interaction with a ready-made.txt file. [ABSTRACT FROM AUTHOR]

At present, the formation mechanism of gas hydrate (hereinafter referred to as hydrate) plugging in the wellbore during deepwater drilling is not clear, so there are problems such as the overuse of hydrate inhibitors and the low utilization efficiency of inhibitors. Therefore, in view of the risk of hydrate formation and plugging under different working conditions during deepwater drilling, research was carried out on the wellbore hydrate formation area and wellbore hydrate deposition and plugging. Taking an atmospheric well in the South China Sea as an example, the wellbore annulus temperature field under different working conditions was combined with the hydrate formation phase curve to analyze the hydrate formation plugging risk under different working conditions during deepwater drilling, and the hydrate formation risk region of the wellbore under different working conditions was obtained. The effects of the drilling fluid circulation rate, injection temperature and drilling fluid viscosity in the wellbore annulus on the risk zone and subcooling of the wellbore hydrate formation were predicted. A deepwater drilling wellbore hydrate deposition plugging model was developed, based on which the dynamic deposition of the hydrate in the wellbore was predicted quantitatively. The results of the study showed that: (1) Increasing the circulation rate of drilling fluid, drilling fluid inlet temperature and drilling fluid viscosity during deepwater drilling can effectively reduce the hydrate formation region and subcooling, thus reducing the hydrate formation. (2) The risk of plugging by hydrate formation basically does not occur during normal drilling. (3) Under the condition of using seawater bentonite slurry drilling fluid, the safe operating time for stopping drilling is 20 h, and the safe operating time for shutting in and killing the well is 30 h. [ABSTRACT FROM AUTHOR]

An investigation into the mechanical properties of K55, N80, and P110 steels commonly used for casing drilling was carried out together with microstructural and fractographic analysis. The results show that P110 steel consisted of almost fully tempered martensite and exhibited a synergy combination of static tensile, dynamic impact, and fatigue crack propagation properties among the three steels, possessing a higher fatigue limit and deeper crack tolerance before failure occurred. The K55 steel consisted of the pearlite and network structure of ferrite and possessed a high strain hardening exponent and low impact property, which led to the more suitable application under incidental large overload and temperature change, but it was unsuitable under the condition of higher impact force. The properties of N80 steel were moderate, and its fatigue property was higher than that of K55 and lower than that of P110; its incidental overload resistance was also higher than that of P110. The casing drilling steel can be selected according to the environment. [ABSTRACT FROM AUTHOR]

In this technical note, we add to the literature the analytical solution of the heat equation with radiation boundary conditions for an instantaneous point source in a hollow sphere. Instead of using the conventional method of the Laplace transfer and inverse Laplace transfer that requires intricate integral in the complex plane, we present a new approach to derive the analytical solution in the time domain. First, we express the instantaneous point source as the initial condition in terms of Dirac delta, e.g., Eq. (2), which is further expressed in the form of the general solution, i.e., Eq. (18). Subsequently, we determine the solution coefficients and obtain the analytical solution. Two special cases with prescribed surface temperature and no-flux boundaries are presented to demonstrate the solution. This solution is of practical importance in many scientific and engineering applications, such as pore pressure prediction in reservoir engineering, thermal analysis of casing in drilling engineering, and determining the relaxation process in nuclear magnetic resonance (NMR). [ABSTRACT FROM AUTHOR]

Most old oil and gas fields worldwide are depleted, making drilling in these sedimentary zones extremely difficult, especially in complex pore pressure regimes when they are accompanied by over-pressure zones. Considering that typical wellbore stability studies provide a conservative mud density curve to prevent wellbore failure, dynamic geomechanical approaches are required to provide more flexible and manageable drilling in such complex cases in order to address anticipated drilling obstacles. This study aims to apply the more dynamic concept, known as "depth of damage" (DOD), in the El Morgan oil field, Gulf of Suez Basin, to deliver a more optional mud density window that helps in the safe drilling of different pore pressure regimes within the area, as well as the implications of applying this drilling strategy in the studied basin. In this paper, well logging and downhole measurements were used to develop a 1D geomechanical earth model and infer the in situ stresses in the studied boreholes, and the modified Lade failure criterion was used to conduct the wellbore stability analysis. The study revealed that the El Morgan sedimentary succession has a complex and varied pore pressure regime. Applying the DOD approach introduces multiple mud density scenarios that can lead to successful drilling and avoid unexpected incidents while drilling. The key benefit of the DOD approach is that it widens the safe mud density window to be less than the shear failure with an acceptable amount of failure. This study provides insights into unconventional techniques such as underbalanced drilling techniques that can be used under manageable conditions in mature basins. Furthermore, the DOD approach is compared to the conventional wellbore stability analysis or breakout depth approach, and the main differences, merits, and demerits of each were discussed in this study. [ABSTRACT FROM AUTHOR]

Fracture pressure models are used to create pre-drill fracture pressure–depth plots that are essential to the design of drilling and casing programmes in oil and gas wells, and for the future development of carbon capture and underground storage. Some of these models include an empirical term (stress ratio) that relates effective horizontal stress to effective vertical stress. Based on the literature, the stress ratio is assumed to vary with compaction and can be calculated from Poisson's ratio (ν). An alternative to models that utilize the stress ratio term is a model that relates fracture pressure to a constant fraction of the vertical stress. This paper demonstrates that a constant fraction of vertical stress is equivalent to a stress ratio that increases slightly with depth. Estimation of how the ν changes with compaction is complicated by the multiple methods that are commonly employed to measure ν. The available static and dynamic ν data suggest a substantial decrease in ν with porosity reduction. Evaluation of in situ ν data from leak-off tests (LOTs) and associated fluid pressure data in Tertiary basins indicates that in situ ν does not decline as rapidly as indicated by the other methods of ν determination. In situ ν data indicate that calibration of the stress ratio from traditional ν methods is not appropriate and may substantially underestimate the fracture pressure (FP). Fracture pressure models that utilize a constant fraction of vertical stress or estimate the stress ratio empirically from LOT data should be employed for pre-drill estimation of fracture pressure. Thematic collection: This article is part of the Geopressure collection available at: https://www.lyellcollection.org/cc/geopressure [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The nonlinear dynamics of a drill string in a supersonic gas flow taking into account supporting stabilizers is considered. • The lumped-parameter method can be effectively used for modeling drill string nonlinear vibrations under external loading. • The optimal number and location of stabilizers allows considerably reducing the amplitude of drill string vibrations. In this paper, we study the nonlinear dynamics of a drill string under the effect of external loads in a supersonic gas flow, taking into account supporting stabilizers. The case of the drill string spatial lateral vibrations, which are the main cause of the drilling equipment failures, is considered. To account for nonlinear effects, a mathematical model based on the general relations of Novozhilov's nonlinear theory of elasticity is developed. The discretization of the model is conducted using the lumped-parameter method. The explicit fourth order Runge-Kutta method is utilized for obtaining a numerical solution for the studied system. The effect of damping elements (supporting stabilizers) on the drill string lateral vibrations is analyzed. Numerical illustrations are presented, and the corresponding recommendations for deep and shallow drilling are given. [ABSTRACT FROM AUTHOR]

Earthquake is one of the most destructive natural disasters. Usually it is followed by a great number of human casualties, material losses and underlying consequences. Therefore organization of efficient medical aid in regions that suffer of earthquakes is an essential task for disaster medicine services. There exists a number of regulations that define the amount of medical aid needed considering the disaster extent. However, they are usually heuristic and based on the rare disasters cases and drills. What is more, they usually prescribe using only uniform medical teams and do not consider involving specialized medical teams that can be vital in certain scenarios. In this study we propose a novel approach to investigate possible medical response teams combinations in temporary disaster medical facilities. To achieve that, we model the workflow of a field hospital to investigate optimal amount and complement of required medical teams in earthquake conditions. Our simulation model considers incoming flow intensity and patients distribution over injuries extent and localization. Moreover, we compare universal and specialized medical teams to discover limits to applicability of different field hospital personnel configurations. For each modeling scenario we found optimal amounts of universal and specialized medical teams. Our findings can be used for emergency policy making to help to define a structure of required medical aid. [ABSTRACT FROM AUTHOR]

In this work, an extremely intense fault-slip rockburst case, with a local magnitude of 2.3, observed in a deep tunnel in southwestern China was introduced as a case study. The rockburst caused a large economic loss and delayed the construction schedule for nearly 2 months. In-situ failure analysis, geological surveys, and microseismic (MS) monitoring were carried out to study the development and occurrence mechanisms of fault-slip rockburst. The fault-slip rockburst occurred in the hanging wall of a structure plane with dark green filling material and the rock mass slipped along the structure plane. It shows characteristic of intermittent occurrence, which results in great psychological pressure on workers. The dominant frequency of the rockburst MS event during the fault-slip rockburst is 13 Hz, which shows that the fault slip rockburst can be captured by the MS monitoring system. Extremely intense MS activity was recorded during the rockburst. The development and occurrence processes of the fault-slip rockburst were studied using this MS information. The stress evolution during the rockburst was studied by analyzing the dynamic stress drop. For the evolution mechanism of the fault-slip rockburst, many tensile fracture events occurred during the development stage, and a few shear fractures, corresponding to structure plane dislocation, occurred before the occurrence of the fault-slip rockburst. The presence of a large natural structure plane resulted in a higher stress and crack extension, and reduced the length of the penetration path, resulting in a stronger destructiveness. The results can be used for the further research on fault-slip rockbursts and planning appropriate warning and mitigation measures. Highlights: An extremely intense fault-slip rockburst with local magnitude of 2.3 in a deep tunnel was introduced. Occurrence characteristics of fault-slip rockburst were analyzed. The development and occurrence mechanisms of the fault-slip rockburst including the fracture type and evolution mechanism, were studied. [ABSTRACT FROM AUTHOR]

The drilling process is an important step in petrochemical industries, but the drilling process is risky and costly. In order to improve the safety and cost the impact of faults in the drilling process, this paper proposes intelligent moving window based sparse principal component analysis (MWSPCA) integrating case-based reasoning (CBR) (MWSPCA-CBR) in the fault diagnosis of the drilling process in the petrochemical industry. Through introducing sparsity into the PCA model, the Lasso constraint function of the MWSPCA method is used to optimize the sparse principals. The corresponding T2 and Q statistics calculated by the selected sparse principals decide whether the faults have occurred, and the occurrence time of the anomaly is quickly located based on the MWSPCA method. Then the CBR method is used to analyze the anomaly data to identify the possible fault types, and provide the relational handling methods for real-time monitoring experts. Finally, the MWSPCA method is verified based on the intelligent diagnosis of the Tennessee Eastman (TE) process, reducing false negatives and false positives and improving the accuracy rate and the diagnosis speed. Furthermore, the proposed method is applied to analyze the data of the drilling process. The experimental results demonstrate that the proposed method can effectively diagnosis faults in the drilling process and reduce risks and costs in the petrochemical industry. [Display omitted] • An improved moving window sparse principal component analysis-based case based reasoning is proposed. • The moving window sparse principal component method is verified based on the diagnosis of the Tennessee Eastman process. • The intelligent fault diagnosis framework of the drilling process is obtained. • The proposed method can effectively diagnosis faults in the drilling process. • The proposed method can reduce risks and costs of petro chemical engineering. [ABSTRACT FROM AUTHOR]

The Semmering Base Tunnel (SBT), with a total length of 27.3 km, is one of the leading construction projects of the Baltic-Adriatic Railway Network. The tunnel connects the two federal provinces of Lower Austria and Styria and cuts through the eastern part of the Alps. The construction lot SBT 1.1-Tunnel Gloggnitz is characterized by a complex geological- and hydro-geological architecture containing alternating competent geological structures, major fault zones, and corresponding geological transition zones. There are three main water-bearing formations at the construction lot SBT 1.1: (a) Karst-prone blocky limestone with an initial water pressure of 10 bar. The discontinuities form a highly permeable interconnected joint network with a significant storage coefficient of the groundwater table. (b) Massive to blocky dolomite with an initial water pressure of 25 bar. The systematic discontinuities and disturbed zones of subsidiary structures with karst form a permeable, interconnected joint network. (c) The transition zone of the limestone to base structure marks the most challenging area for consolidation- and sealing grouting. Weak fault rocks characterize transition zones with intense fracturing. However, as subjected to high groundwater pressure of 10 bar, these zones are associated with the potential of flowing ground conditions. Based on the overall project requirements, specific drilling- and grouting methods and materials for pre-excavation grouting have been established and successfully implemented in the construction process. The innovations include a Standpipe-Packer substituting a conventional steel standpipe, a specifically cased drilling system with grouting inserts to prevent erosion within the borehole and allow for defined grouting. In addition, this Grouting-Pipe system replaces standard tube-à-manchettes and controls the flushing while drilling with preventers. Finally, a combined cement-polyurethane grout mix (Hybrid Grout) was implemented to stabilize the grout. The implementation of these measures will be discussed in detail, and their benefits to the construction process will be highlighted. [ABSTRACT FROM AUTHOR]

Chronic otitis media is defined as the chronic inflammation of the mucoperiosteal lining lining of the middle ear cleft which presents with recurrent ear discharge through tympanic membrane perforation. The study was planned to evaluate the patency of the aditus ad antrum in cases of chronic otitis media mucosal type, and its correlation with various direct and indirect indicators of blocked aditus. The prospective longitudinal study was conducted on 100 patients with chronic otitis media mucosal type. The commonest complaint of patients was ear discharge (100%) followed by hearing impairment in 72% patients.Tympanoplasty with antrotomy was performed. The patency and dimensions of the aditus ad antrum were assessed by saline water test. In 41% cases saline test showed blockade, on further drilling patency achieved in 27 cases with minimal drilling and dissection of mucosa with or without fibrotic mucosal bands. In rest 14 cases widening of aditus and atticotomy was required to achieve patency. Out of these nine were having associated tympanosclerosis and five were having edematous mucosa. Ossicular necrosis was seen on 18 cases. Presence of myringosclerosis and polypoidal edematous mucosa increases the probability of an obstructed aditus ad antrum. Mastoid antrostomy and water test for patency can be performed without additional cost and risk to the patient in minimal time and can be considered as the surest indicator of patency of aditus ad antrum. [ABSTRACT FROM AUTHOR]

In karst topography, hidden caves or underground rivers may imperil the safety of tunnels. It is critical to accurately detect the location and geometric shape of hidden karst caves for assessing the safety of tunnels. This paper reports a case where a large karst cave was exposed during the construction of the Nongmo tunnel in Duan County, Guangxi, China. A 2D ground‐penetrating radar survey was employed to preliminarily detect the distribution of hidden karst caves along the tunnel axis. Advanced drilling was used to obtain the velocity of electromagnetic waves and verify the 2D ground‐penetrating radar detection. Ground‐penetrating radar 3D grid detection was carried out for further detecting the geometric shape of the hidden karst caves. Rotary thrust power ratio, which is a function of drilling speed, rotating speed, propulsion pressure and torque, was proposed to reflect the integrity of the surrounding rocks. It was found that the depth of the peak value in the rotary thrust power ratio curve is consistent with that of the amplitude jump in ground‐penetrating radar A‐scans and in time–frequency distributions. The results of 3D attributes analysis indicate that due to the variation of highlights in different ground‐penetrating radar signal attributes, the obtained karst cave shapes using different attributes would be various. A multi‐attributes fusion method was proposed to generate a data volume considering various attributes. The 2D geometric shapes at different depths were obtained using the anomalous body lineament in the generated date volume slices. The 3D geometric shapes were reproduced by combining the obtained 2D geometric shapes at various depths. Based on different detection and analysis methods, the outline shape of karst caves at YK364 + 199 ∼ YK364 + 184 of the Nongmo tunnel was revealed in detail. [ABSTRACT FROM AUTHOR]

Guardian- Guardians are different from guardians ad litem. While a guardian ad litem should consider someone's wishes in determining what their best interests are, the GAL is not beholden to the wishes in the same way an attorney, or even a guardian, is. Many people (even attorneys) can be confused by the variety of terms and actors involved in guardianship cases. [Extracted from the article]

A great deal of attention is currently paid to recycling or reusing carbon fibres, as it improves sustainability and the lifetime of carbon products. The applicability of recycled carbon fibre–reinforced polymer (rCFRP) composite materials is supported by the results of material scientists; however, the machinability of rCFRPs has not been analysed yet. The machinability of virgin and rCFRPs was compared by analysing cutting force and torque in drilling. Six different CFRPs (virgin and recycled CFRPs with different reinforcing structures) were drilled at three feed levels using two different solid carbide cutting tools. The cutting force and torque were measured with a KISTLER 9257BA dynamometer, processed, and analysed by fast Fourier transformation (FFT) and analysis of variance (ANOVA). The experimental results proved at a significance level of 0.05 that the recycled/virgin status of the applied CFRPs significantly influences both the thrust force and drilling torque of each CFRP. Furthermore, the cutting force and torque are higher in rCFRPs than in virgin CFRPs at each reinforcing structure. The present study suggests spreading rCFRP applications, as there are no essential barriers against them from the point of view of drilling force and torque. [ABSTRACT FROM AUTHOR]

The composite casing drilling technology in a deep-water riserless well construction is the technology providing drilling of the tandem borehole composed of the surface conductor borehole and the surface casing borehole in a one-trip drilling operation. The composite casing is put into place and is cemented in one trip. The composite casing drilling technology not only combines the advantages of the drilling method and the jetting technology but also overcomes the limitations of both technologies. The composite casing drilling technology has been successfully applied in the Mozambique block A drilling projects. The results of the field application show that this technology is able to provide secure and efficient drilling operations, which can considerably reduce the installation time and the costs. In this paper, based on the example of application in the Mozambique block A gas field, the process of the composite casing drilling technology is described in detail. Then, the authors analyze the field conditions and put forward an optimization method. The optimization method is applied to select the optimal technology for drilling and installing the surface conductor and the surface casing. [ABSTRACT FROM AUTHOR]

In offshore maritime operations, automated systems capable of maintaining the vessel’s position and heading using its own propellers and thrusters to compensate exogenous disturbances, like wind, waves, and currents, are referred to as marine dynamic positioning (DP) systems. DP systems play a central role in several marine operations, such as drilling, pipe-laying, coring, and ocean observation. These operations are the primary cause of fuel consumption, having a strong impact on the overall footprint of the vessel. For this reason, we will face the problem of optimal thrust allocation of an over-actuated vessel to maintain position and heading with minimal fuel consumption. State-of-the-art approaches simplify this problem by roughly approximating it and obtain a simple, mostly convex, optimization problem that can be solved in near-real time by the automation system. In this article, we improve current approaches with the following contributions. We will exploit a higher fidelity representation of the physical system, and we will manipulate the resulting optimization problem accordingly, to allow for near-real-time solutions on conventional computing platforms on-board. We evaluate the quality of the proposal with a case study on a drilling unit equipped with six thrusters. The results will show that it is possible to achieve up to 5% of fuel savings with respect to conventional approaches. Note to Practitioners—This article was motivated by the problem of minimizing fuel consumption in thrust allocation of DP systems. The current approaches simplify this issue by adopting simpler, yet related, optimization problems as surrogates, keeping the problem tractable for near-real-time control. We propose, instead, to solve the original problem with state-of-the-art modelization of the physical system and exploit reasonable and theoretical proprietaries to achieve optimal solutions in near-real-time. The results on a drilling unit will show additional fuel savings of up to 5% with respect to alternative state-of-the-art approaches. [ABSTRACT FROM AUTHOR]

Many solutions have been executed to mitigate the wellbore instability problem including improving mud inhibition with chemical additives, raising mud weight to mechanically support the wellbore, and modifying casing design to accommodate extra-large diameter surface casing with the drawback of increasing well cost. Despite these solutions, the operator is still plagued by continuous hard reaming during tripping operations, several dill string pack-off sticking incidents, and the inability to get the casing to the bottom. This paper examines the effect of implementation of Non-retrievable drilling with casing technique to optimize drilling and overcome the hole instability problems in West of Nile (WON) field is located in the Western Desert of Egypt and operated by Qarun Petroleum Company. This solution is unique in terms of adaptability and simplicity, a few adaptations are required for a standard drilling rig to be able to get casing to bottom by rotating, reciprocating, and circulating simultaneously. Applying this technique optimize drillings, reduces cost, and improves safety. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Palaeoecological studies of drilling intensity (DI), drawing ecological and evolutionary inferences, generally assume that drilled and undrilled specimens are equally preserved in the fossil record, because of the fact that the presence of drillholes does not affect preservation potential during sediment compaction. However, another facet that has not been studied conclusively is the taphonomic imprint on DI in a pre-burial scenario. If drillholes add weakness to a shell's mechanical strength, drilled valves may preferentially be broken during post-mortem transportation, before its' burial within sediment. In the present study, we test this hypothesis with a dataset involving DI and taphonomic status of two bivalve, Donax scortum and Mactra luzonica and two gastropod, Natica tigrina and Turricula javana species from Chandipur, India. Taphonomic status of each specimen is determined by relative preservation of its' morphological characters. In case of both bivalves and gastropods, DI is found to be highest among the best preserved specimen and, thereafter, declines with increasing taphonomic degradation. When shell size is included in analyses, DI still shows an inverse relation with taphonomic alteration. This observed inverse relationship between drilling intensity and taphonomic imprint suggest that drilled shells may be vulnerable to breakage by pre-burial taphonomic processes. [ABSTRACT FROM AUTHOR]

Presented here is the development of a predictive model for impedance of single-degree-of-freedom (SDOF) and two-degree-of-freedom (2DOF) acoustic linings that is suitable for the design stage of suppression of inlet noise for turbo-fan engines. It is required that over a probable range of lining physical parameters and operating conditions the impedance spectrum is predicted with accuracy sufficient to support a lining design process and assessment of achievable attenuation. The starting point is a published impedance model for SDOF linings that primarily focuses on the transfer impedance of conventional and micro-perforate face sheets with grazing flow. This is expanded here to include 2DOF linings, introducing new issues related to transfer impedance of the inserted septum. Problems addressed are related to the septum insertion process that can change thickness, hole diameter and open area ratio of the uninstalled septum, and introduce blockage. Required empiricism is discussed and models for face sheet and septum-in-core transfer impedance are derived, applicable to a specific range of sheet thickness, hole diameter, and open area ratio. Manufacturing processes considered are mechanical drilling in the case of the carbon fiber laminate face sheet that is conventional perforate, and laser drilling in the case of the epoxy film micro-perforate septum material. Benchmarking is carried out by comparison of acoustic field predictions, using the proposed lining model in an FEM propagation code, with measured data from a grazing flow duct facility. Test samples include SDOF and 2DOF linings, including cases with three segments, each with distinct physical properties. Example results of comparisons are shown to highlight the fidelity of the impedance model over a frequency range compatible with the grazing flow duct geometry. [ABSTRACT FROM AUTHOR]