Steel Casing Research Articles

Cased-hole reverse time migration imaging using ultrasonic pitch-catch measurement: Theory and synthetic case studies

Cement-bond evaluation is of great significance in oil/gas development, geothermal production, and CO2 storage. Advanced ultrasonic pitch-catch measurement exhibits poor performance in determining a cement-formation interface due to weak reflections from the cement-formation interface (third interface echo) in nonaxisymmetric complex ultrasonic environments. To deal with this issue, we use a reverse time migration (RTM) approach for ultrasonic pitch-catch measurements to image the cased-hole structure, especially for the cement-formation interface. To further enhance cased-hole RTM feasibility, a phase-shift interpolation technique is applied to reconstruct ultrasonic array waveforms from limited receivers in the pitch-catch measurement. Synthetic examples demonstrate that RTM is capable of imaging the cement-formation interface with a high resolution under various eccenterings of casings and tools. This study illustrates that small errors introduced by phase-shift interpolations do not greatly degrade the imaging result of RTM. Furthermore, tests for inclined cement-formation interfaces demonstrate that the RTM is able to recover the true position and geometry of the cement-formation interface when a smoothed velocity model is available. In addition, although RTM is sensitive to the velocity perturbation, it is possible to image the cased-hole structure by using a multistep strategy assuming that the position and thickness of the steel casing are unknown.

Laboratory Machine Verification of Force Transmission Provided by Friction Acting on the Drive Drum of a Conveyor Belt

The paper presents the measured values of tensile forces acting on transmission idlers in the upper and lower run of a conveyor belt placed on a laboratory machine designed at the Department of Machine and Industrial Design, Faculty of Mechanical Engineering, VSB-Technical University of Ostrava. The tensile forces detected by two strain gauge load cells and recorded using DEWESoft software were used to calculate the friction coefficient, which acts on the surface of the driving drum casing and the conveyor belt. The friction coefficient at the slip point, or during the slippage of the conveyor belt on the rubber or steel casing of the driving drum, was determined for two states of the surfaces that are in contact. Experimental measurements on a laboratory machine determined four values of friction coefficients for two types of drum surfaces and for two states of contact surfaces, which were compared with the recommended standard values. The measured values reached higher values in comparison with the values given by the CSN standards. The highest deviation of 273.3% is achieved using a steel wet surface, and the lowest deviation of 106.3% is achieved when using a rubber dry lining for the driving drum casing. On the presented laboratory machine, it is possible to measure tensile forces for different speeds of movement, different belt angles on the driving drum, various types of belt surfaces, different types of drum casing linings, and different sizes of tension forces for the endless loop of the conveyor belt. For these characteristics of the conveyor belt, the magnitude of the friction coefficient acting between the belt and the drum surfaces can be determined.

Behavior of laterally loaded cast-in-place (CIP) piles with double steel casings embedded in bare hard rock in deep water areas

Difficulties can be encountered during the installation of a cast-in-place (CIP) pile in bare hard rock located in deep water areas, including the installment of the steel casing and mud leakage during drilling. We proposed a novel CIP pile consisting of inner and outer steel casings, a steel reinforced concrete (RC) shaft embedded in the rock, and a hollow concrete cylinder between the two steel casings. A numerical study was conducted on the novel CIP pile with double steel casings (CIPDSC) and a CIP pile with one steel casing (CIPASC). The results showed that the load could be transferred from the CIPDSC to the rock mass by two methods: from the steel casing to the RC shaft and the rock mass, and from the outer steel casing and the hollow concrete cylinder to the rock mass. The load–displacement curves of the CIPDSC were characterized by five points: debonding at the interface of the inner steel casing and RC, tensile yielding of the inner steel casing, tensile yielding of the outer steel casing, compressive yielding of the outer steel casing, and compressive yielding of the inner steel casing.

Development of small-scale buckling-restrained brace analog for physical experiments of structural systems

Experimental testing is critical for evaluating the performance of novel structural systems. However, the cost of full-scale testing can be limiting. Small-scale testing provides a lower cost alternative that can produce reliable data if each component of the scaled model is properly developed. Given their stable hysteretic behavior, buckling-restrained braces (BRBs) are featured in several seismic force-resisting systems. The design of typical BRBs involves an axially yielding steel core that is prevented from buckling by a concrete casing. Designs for adaptable and easy-to-implement small-scale BRBs that can be included in structural testing have not been established. In this work, a small-scale BRB analog is developed that utilizes a core steel yielding plate that is prevented from buckling by a pair of steel casing plates. A flexural yielding mechanism is employed in the small-scale BRB analog, which allows for practical dimensions and the ability to independently tune brace stiffness and strength. Prototype braces were fabricated and validated through quasi-static cyclic testing in which they exhibited the full and stable hysteretic behavior characteristic of BRBs. To aid in the use of this BRB analog by others, numerical results were utilized to generate empirical equations that relate the strength and stiffness of the scaled BRB to the archetypical geometry of the core plate. Given its ability to deliver a stable hysteretic performance, the wide range of strength and stiffnesses that it can provide, and its easy reusability, the developed device is a good choice for experiments where a small-scale BRB analog is needed.

Additive manufacturing and characterization of a stainless steel and a nickel alloy

Abstract Recently, additive manufacturing is of interest, and there is a trend to study additively manufactured materials such as Inconel 718 and 316L stainless steel. Additive manufacturing brings the easiness of production of complex geometries, avoids expensive tools, helps achieve interesting microstructures and obtaining promising results for future applications. Since the additive procedure is sensitive to many fabrication variables thereby affecting the microstructure and mechanical properties. This motivation promotes investigating the additively manufactured microstructure of 316L stainless steel and Inconel 718. While 316L stainless steel was fabricated using an electron-based powder bed fusion manner, directed energy deposition was preferred for Inconel 718. Samples were examined utilizing optical and scanning electron microscopes. Results suggest processing of 316L stainless steel gives rise to the same porosity rate as Inconel 718. Bimodal equiaxed austenite grain morphology was observed whereas no dendrite presence was detected for 316L stainless steel. Additive manufacturing types do not cause a significant change in the level of porosity for Inconel 718 alloy. Unlike the case of stainless steel, additive manufacturing results in dendritic microstructure formation in Inconel 718 whereas powder bed fusion-type production triggers a better refinement compared to that of directed energy deposition.

Three-dimensional numerical simulation of wave-induced seabed response around a dumbbell-shaped cofferdam

The dumbbell-shaped cofferdam has a large-scale and complex geometric shape, which may result in a complicated fluid-structure-seabed coupling mechanism and sophisticated seabed response around the structure. To investigate the wave-induced oscillatory seabed response around a dumbbell-shaped cofferdam, this study simulates the wave-cofferdam-seabed interaction process using a numerical model within the OpenFOAM framework. In this study, the finite volume method is applied to both the wave model and seabed model, thus ensuring the computational accuracy of this study. Biot's poro-elastic theory (u-p approximation) is considered as the governing equation for the dynamic response of the porous seabed, and the fluid motions are simulated based on the Reynolds-averaged Navier–Stokes equation. First, the accuracy of the numerical model for simulating wave-induced soil response is validated against existing experiments. Next, the effects of the submerged depth, wave incidence angle, and wave height on the oscillatory pore pressure response are studied in detail. Finally, momentary liquefaction around the dumbbell-shaped cofferdam is examined. The numerical results indicate that the wave-induced oscillatory seabed response around the cofferdam is considerably affected by the wave height but less affected by the wave incident angle. Moreover, the distribution of the wave-induced pore pressure in the vicinity of the dumbbell-shaped cofferdam is complex, and the maximum liquefaction depth around the cofferdam occurs near the steel casing along the centerline of the cofferdam.

Thermomechanical behaviour of well cement in different geological formations under the coupled effects of temperature and pressure

It is crucial to ensure that the cement sheaths remain intact in all types of deep well applications subject to high temperatures and high pressures underground. It should be noted, however, that the behaviour of annulus cement sheath is not self-controlled and is governed by the response of steel casing and the surrounding rock formation in such extreme underground conditions. In this study, we investigate the thermomechanical response of wellbore materials in a typical oil well consisting of steel casing, annulus cement sheaths and surrounding rock formations subjected to continuous steam injection. A section of an oil well was simulated by using the COMSOL Multiphysics, a finite element method, using Class G Portland cement as the annulus cement. In two formation scenarios, stiff (carbonate) and compliant (sandstone), temperature and pressure were coupled to evaluate wellbore material behaviour. It was found that wellbore materials in carbonate were more susceptible to stress than those in sandstone. Despite the fact that all materials reached their highest temperatures in both formations, the retention time of the maximum temperature in the cement sheath in sandstone was shorter than in carbonate. Regardless of the thickness of the cement sheath, the highest strains were located at the casing-cement interface in carbonates. As a result of the temperature and pressure ramp, the cement sheath in sandstone failed by generating tensile radial cracks along the lowest layer thickness of the cement sheath. In compliant formations such as sandstone, the cement sheath would likely fail due to tensile cracking along its lowest thickness.

Spectroscopy-based smart optical monitoring system in the applications of laser additive manufacturing

The potential defects during the additive manufacturing (AM) process greatly deteriorate the mechanical properties of the fabricated structures and, as a result, increase the risks of part fatigue failure and even disasters. As laser additive manufacturing is such a complex process, many different physical phenomena such as electromagnetic radiation, optical and acoustic emission, and plasma generation will occur. Unlike vision and acoustic methods, the spectroscopy based smart optical monitoring system (SOMS) provides atomic level information revealing mechanical and chemical condition of the product. By monitoring plasma, multiple information such as line intensity, standard deviation, plasma temperature, or electron density, and by using different signal processing algorithms such as vector machine training or wavelet transforming, AM defects have been detected and classified. Utilizing two fiber optic components, a bifurcated fiber and a split fiber, the experimental results were performed to improve SOMS signal-to-noise ratio. Defects, including subsurface pores and sudden changes of process parameters including shielding gas shut-off and foreign substance, were identified by the spectroscopy based SOMS. For chemical composition characterization, a degree of dilution in terms of chemical element variation is identified by a spectral peak intensity ratio through the SOMS. It turned out that the information on the Cr/Fe ratio of deposit at a certain layer is vital to design the mechanical property in the IN625 deposition on the mild steel case. The SOMS has also demonstrated that the chemistry ratio can be determined from the calibration curve method based on the known alloy samples and that the ratio of the maximum intensities of multiple species provides more information about the quality of the alloy.

Wave current force test of deep water foundation of bridge in marine environment

As a key parameter in the design and construction of the Sea Crossing Bridge, the wave and current load on the pile foundation has been the subject of extensive research. The magnitude and distribution of wave and current loads on pile foundations are crucial for the safety of the foundation. Based on Male Airport Island Bridge Project in the Maldives, the wave current force of platform pile and steel casing in different construction stages is investigated, and the horizontal force and bending moment of the foundation under various wave and current parameters are tested using an indoor model. The results are as follows: 1) With the same effective wave height and wave period, the maximum horizontal force and bending moment on the pile exhibit a linear relationship to the wave velocity. Under the same water depth, the combined wave current force is greater than the sum of wave force and simple current force, with a maximum difference of 70%; 2) Under 2-year return period wave and current conditions, the horizontal stress on a single platform pile and steel casing increases linearly with the increase in height, and there will be nonlinear relationship with 10-year return period wave and current conditions; 3) With more platform piles and steel casing, the front row piles have obvious protective effect on the rear row piles, and the horizontal force and bending moment of the overall structure increase nonlinearly.

Modelling Frictional noise using Artificial neural network and Regression: The case of steel on steel reciprocating sliding

Modelling Frictional noise using Artificial neural network and Regression: The case of steel on steel reciprocating sliding

Modelling frictional noise using artificial neural network and regression: the case of steel on steel reciprocating sliding

Modelling frictional noise using artificial neural network and regression: the case of steel on steel reciprocating sliding

Влияние остаточных напряжений в стали У8 с грубопластинчатым перлитом на магнитную проницаемость

The physical reasons for the formation of peaks of that part of the magnetic permeability, which is caused by transitions of only 90-degree domain boundaries µ90(H0) in deformed steel U8 with coarse-plate perlite when the field changes along the back of the hysteresis loop, are considered. It is shown that the orientation relations of the Patch-Pitch between single-crystal ferrite and cementite plates in U8 steel lead to the appearance of a constant angle between the magnetic moments of these plates and, consequently, to the appearance of corresponding local scattering fields. The latter can significantly affect the values of the peak fields of the curve µ90(H0). Theoretical expressions for these fields containing contributions of scattering fields that should be taken into account when determining residual compressive stresses are obtained. It is also shown that to determine the residual stresses, two expressions for peak fields are not enough, and additional experiments are needed, as which it is proposed to use the dependences of the coercive force on elastic tensile stresses. This leads to a complication of the algorithm for determining residual compressive stresses in comparison with the case of low-carbon steels. A method for estimating the values of local scattering fields in the ferrite parts of U8 steel grains with residual compressive stresses is proposed.

Estimation of residual compressive stresses in deformed U8 steels with coarse-plate perlite by field dependences of magnetic permeability

The physical reasons for the formation of peaks of that part of the magnetic permeability, which is caused by transitions of only 90-degree domain boundaries μ90(H0) in deformed steel U8 with coarse-plate perlite when the field changes along the back of the hysteresis loop, are considered. It is shown that the orientation relations of the Patch-Pitch between single-crystal ferrite and cementite plates in U8 steel lead to the appearance of a constant angle between the magnetic moments of these plates and, consequently, to the appearance of corresponding local scattering fields. The latter can significantly affect the values of the peak fields of the curve μ90(H0). Theoretical expressions for these fields containing contributions of scattering fields that should be taken into account when determining residual compressive stresses are obtained. It is also shown that to determine the residual stresses, two expressions for peak fields are not enough, and additional experiments are needed, as which it is proposed to use the dependences of the coercive force on elastic tensile stresses. This leads to a complication of the algorithm for determining residual compressive stresses in comparison with the case of low-carbon steels. A method for estimating the values of local scattering fields in the ferrite parts of U8 steel grains with residual compressive stresses is proposed. Keywords: residual compressive stresses, deformed steel U8 with coarse-plate perlite, magnetic field, magnetization, magnetic permeability, 90-degree domain boundaries (DB), large-angle vicinity(LAV) and small-angle (SAV) grain boundaries of steel, orientation relations of the Patch-Pitch.

Waveguide Analysis of Radiofrequency Transmission in Well Tubulars for Electromagnetic Heating of Heavy Oil

This paper presents the numerical modelling and simulation of a 2D vertical well tubular model excited by a coaxial radiofrequency transmission line placed in its annular space for the purpose of downhole RF energy transmission. The study identifies the mechanism of energy losses due to coupling between the transmission line and steel tubing and casing using resonance mode analysis. The design of a left-handed artificial power line is proposed to minimize the losses due to the right-handed properties of the coaxial transmission line. The design utilizes ideal lumped element method to determine the left-handedness of the right-handed coaxial transmission line over the industrial heating radio-frequency band. The model is developed and simulated using COMSOL multi-physics commercial simulation software. The effect of transmission line position within the annular space on the tangential magnetic field and resulting power losses along the tubing is discussed. It is observed that the resulting artificial power line improves RF power transmission over 60 m depths of the vertical oil well within the industrial heating radiofrequency band.

Evaluating the performance of three sensor types for long-term measurement of suctions in gold tailings

A key aspect of the stability of a tailings dam is the pore pressure regime within the dam. Although gold tailings can exist in an unsaturated state in the field, the measurement of negative pore pressures (matric suctions) in active gold tailings dams is not common. One of the reasons for this may be the uncertainty regarding the ideal sensor type that should be used due to the shortcomings of various types of sensors. To investigate this, a long-term Drying Box experiment was conducted in the geotechnical laboratory at the University of Pretoria. Three sensor types were assessed: a commercially available water potential sensor and two versions of the TUKS tensiometer – a high capacity tensiometer designed and constructed at the University of Pretoria. Gold tailings was deposited in a slurry form and allowed to desiccate. The response from the three sensor types as a result of the change in suctions due to drying and subsequent re-wetting were observed. It was found that the TUKS tensiometer with the steel casing provided rapid, reliable, long-term suction readings. This sensor type is therefore recommended for long-term measurement of suction in gold tailings.

Experimental behavior of truss‐confined buckling‐restrained braces

AbstractBuckling‐restrained braces (BRBs) can effectively improve the stiffness, strength, and energy dissipation capacity of building structures. The key feature of the proposed truss‐confined BRB (TC‐BRB) is an additional truss confining system attached outside the central steel casing. The truss system is composed of several steel open‐web truss frames, thereby providing the required restraining rigidity and reducing the central casing section size and infilled mortar. The overall self‐weight is decreased compared with a conventional BRB, especially in cases of long‐span and large force capacity BRB applications. This research program was conducted to investigate the hysteresis behavior of the TC‐BRBs in terms of truss member response, buckling resisting ability, and cumulative deformation capacity. Six one‐third‐scale TC‐BRB specimens, each 6.3 m long and with different yield capacities, truss frame shapes and sizes, were tested using cyclically increasing loads with or without an out‐of‐plane end drift. The six specimens eventually failed either from global flexural buckling of the entire restraining system or a tensile fracture of the steel core at a very large axial strain. The experimental results demonstrated that the TC‐BRBs can be designed and fabricated to have a very stable and highly repeatable hysteretic response, meeting the American Institute of Steel Construction acceptance criteria. It provides a valuable database to support the further development of design guidelines for the engineering application of the proposed TC‐BRBs.

Effect of electrified surface casing on the interference characteristics of stray current generated by deep‐well anode beds

AbstractCurrently, the impressed current cathodic protection with deep‐well anode beds has been found that the surface casing was charged. In this study, 13 deep‐well anode beds were selected randomly to investigate whether their surface casings were electrified. Possible causes of the electrification of surface casings are also discussed. A numerical model for simulating the geoelectric field of a representative deep‐well anode bed with an electrified surface casing was established and validated by data from on‐site testing. The difference in the interference characteristics between situations with charged and uncharged casings was also discussed. The results showed that 30.7% of deep‐well anode beds had electrified surface casings. The leading root causes may be that the anode cable had been damaged unexpectedly during the construction process or the electrical resistance between the anodes and the surface casing had been reduced dramatically. The peak potential gradient and comprehensive interference intensity were about 20 times and 3–6 times, respectively, those in situations where the casing was uncharged. A polyvinyl chloride surface casing is, therefore, recommended in deep‐well anode beds. Reliable electrical insulation should be implemented if steel casings are used. Furthermore, regular electrification tests on steel surface casings should be conducted during completion acceptance and daily operation.

Study on formability of duplex steel expansion pipe and its threaded joints

The threaded joint of equal well-diameter-expansion pipe is prone to fracture and leakage after expansion forming. The structural integrity and material selection of the expansion pipe threaded joint are the main difficulties. Taking dual-phase steel and other well-diameter expandable casings as the research object, a method combining finite element simulation and experimental verification is used to construct an enhanced constitutive model. Firstly, three kinds of reinforced constitutive models are constructed, and then finite element software is used for simulation, combined with experiments to analyze the axial length of the pipe, pipe wall thickness, thread clearance, material hardness, plastic toughness and microstructure. The results showed that after expansion the top and root of the threaded area of the tube after expansion have greatest change and the residual stress is relatively high. Microhardness and Charpy impact tests were carried out on the pipes before and after expansion to study the changes in hardness and toughness. It can be found that the toughness of the expansion pipe has decreased, and although the wall thickness will be reduced, the strength of the pipe will be significantly increased, which is the effect of work hardening. The topography of the crack surface is nearly identical over the entire range of expansion ratios considered in this study. In addition, the microstructure of the unexpanded and expanded tubes is similar, consisting of ferrite and austenite. This paper provides a theoretical reference for engineering practice.

Correlative full field X-ray compton scattering imaging and X-ray computed tomography for in situ observation of Li ion batteries

Increasing electrode thickness is gaining more attention as a potential route to increase energy density for Li ion batteries although the realizable capacity and rate capability are usually limited by Li+ ion diffusion during (dis)charge, especially at increased (dis)charge rates. It remains challenging to visualize and quantify the low atomic number Li+ chemical stoichiometry distribution inside the electrode within commercially standard battery geometry, e.g. coin cells with stainless steel casings. Here, we map the distribution of Li + chemical stoichiometry in the electrode microstructure inside a working coin cell battery to show the amount of electrode materials contributing to energy storage performance using innovative in situ correlative full-field X-ray Compton scattering imaging (XCS-I) and X-ray computed tomography (XCT). We design and fabricate an ultra-thick (∼1 mm) cathode of LiNi0.8Mn0.1Co0.1O2 with a microstructure containing vertically oriented pore arrays using a directional ice templating method. This novel technique paves a new way to map low atomic number elements in 3D structures and study how the microstructure improves Li + ion diffusivity and energy storage performance.

Key Technology for Construction of Steel-concrete Composite Suspending Cofferdam without Bottom Cover for Platform of Coastal Intercommunication Project

<p>Many bridge piers were built in the Coastal Interconnection Project of the Ningbo Section of the Hangzhou-Ningbo Expressway Double Line. Affected by the tides at the bridge site, the high pile caps are constructed using a suspending cofferdam without a bottom cover. Based on the consideration of various factors such as construction difficulty, safety, cost and construction period, etc. A cement structure is generally adopted as the floor of the suspended box cofferdam. The steel-concrete combined hanging box cofferdam without bottom cover adopts the structure of steel wall plate and prefabricated cement floor, and the partition wall plates are connected by bolts. The steel-concrete composite suspending cofferdam adopts the prefabricated bottom plate and wall plate. The construction sequence is listed as follows: First, weld the load-bearing corbel on the steel casing, and then hoist the prefabricated bottom plate to the steel casing corbel in blocks. Pour the wet joint between the prefabricated bottom plate and install the side plate. After that, pour the cushion after welding the shear plate. Finally, carry out the construction of the cap. During the construction of the project, the connection method between the wall plate and the bottom plate was optimized. The connection of the fine-rolled rebar hanger rod was changed to the steel bar pair pulling, which improved the construction efficiency significantly.</p>