Open Section Research Articles

Novel Responsive Controllable Solidification Plugging Agent to Overcome Lost Circulation Problems in Long Open Hole Intervals

A new type of responsive controllable solidification plugging agent (RCSP) for long open hole intervals was developed, and the sealing characteristics were evaluated. RCSP had the characteristics of rapid water loss, high filter-cake consistency and good residence capacity. The experimental results indicated that the maximum pressure-bearing capacities of plugged zones in 5 mm and 10 mm slotted templets are 16.6 MPa and 11 MPa, respectively. So RCSP is an effective plugging agent for strengthening wellbore stability. RCSP is appropriate for sealing wide range of fracture sizes. Using RCSP-based plugging mud to address lost circulation problems in troublesome thief zones is a very powerful and economical approach. In the future, RCSP might hold great promise to resolve lost circulation problems in multiple leakage zones in long open hole sections.

Forced oscillations of the main gas pipeline open section during the cleaning piston passage

The problem of forced oscillations of an open section of a gas pipeline during the cleaning piston passage belongs to the type of problems of forced oscillations of one-dimensional elastic objects under the influence of a moving inertial load on them. Currently, there are two ways to solve such problems. The first way is related to the integration of the partial differential equation and the solution of such problems is a superposition of eigen-oscillations and accompanying oscillations. The second way does not involve the integration of the partial dif-ferential equation. Methods of generalized coordinates, generalized displacements and various numerical methods belong to the second type of solving. None of the mentioned methods is simple. Therefore, the authors suggest the method, in which the first mathematical model provides the determination of forced oscillations of the gas pipeline section during the passage of the cleaning piston without taking into account its inertial load on the gas pipeline. In future, on the basis of the first model it is planned to develop the second mathematical model which will provide an approximate determination of the deflections of the pipeline axis, taking into account the inertial load of the piston on the pipeline. The purpose of this article is to obtain a solution to the problem of forced oscillations of the pipeline section during the passage of the cleaning piston without taking into account the inertial forces on the pipeline. The problem is solved by partial differential equation, Fourier method is applied. The right side of the non-homogeneous differential equation is decomposed into an infinite series, which is the sum of the produc-tions of the eigenfunctions of the pipeline section free oscillations and the unknown function of time. After finding out this function, the authors determine the unknown time function in the Fourier method and hence the solution of the problem in the form of an infinite series, the summands of which lessen rapidly. The authors calculate the deflections of the pipeline axis along the entire section of the gas pipeline for different points of time, as well as deflections of individual sections changing in time and moments of deflection.

Analytic solution of rectangular plate buckling with rotationally restrained and free edges

In this research a new analytical solution is used for finding the buckling loads of rectangular plates with rotationally restrained edges. Until now, analytical solution were available only for a small number of specific combinations of boundary conditions. The solution method in this study is based on the development of a static solution for a plate. The solution is obtained in series form, and the coefficients are solved to match the edge conditions. The solution fits all the combinations of possible boundary conditions, of the deflection, slope, shear force and bending moment along the edges of the plate. The problem of buckling of part of an open cross section with a free edge is solved analytically. Any number of edges, from one to four, with rotational stiffening springs can be solved. Using this new method, the exact buckling loads and modes are found. The results are verified with published data, and many new cases are presented for uni-axially and bi-axially loaded plates.

Development of an efficient steel truss system using CFS sections: a comparative study with a hot-rolled steel truss

PurposeThe purpose of this paper is to discuss the performance of efficient cold-formed steel (CFS) sections in building a truss system. A comparative study was performed comparing trusses built with cold-formed and hot-rolled sections.Design/methodology/approachMedium-scale specimens were fabricated and tested under monotonic loading. Closed CFS sections (tubular sections) were adopted as compression members of the truss, against the open sections (angle sections) in the hot-rolled steel truss. While as open sections (angle sections) were adopted as tension members in both these cases, the performance assessment was made on the basis of the peak loads carried by the trusses, the vertical deflections and the failure modes exhibited.FindingsThe results of this study indicated that the overall strength, strength-to-weight ratio and overall convenience in terms of cost and fabrication, in the CFS truss was better than that of the hot-rolled one. Also, the judicious utilization of steel which has limited reserves can be achieved.Originality/valueCold-formed and hot-rolled sections are widely used in the steel structures. There are advantages and disadvantages in using each of these configurations, discussed in this work. The advantages are widely known by the scientific community; however, few studies are developed with the purpose of quantifying the gains of each solution. Thus, this work emerges with great innovation, with regard to the experimental evaluation of the trusses' behavior composed of different structural sections.

Modeling of the Vibratory Tube Finisher Container

Abstract The paper is dedicated to the problem of modeling the container of vibratory tube finisher additive manufacturing technology. The aim of the research is to develop an engineering approach of designing a rational model of deformative oscillations of a big size container. A thin-walled open cross section cylindrical beam is used as a model of bend and rotation of the vibratory tube finisher container. A method of division of all components of a strain and deformative state into the main and secondary is used to evaluate variants of a model of the vibratory tube finisher container. A ratio of the principle dimension of a cross section and changing of the stress-strain state is used as a weight parameter of components of potential and kinetic energy. A shear model of a thin-walled beam can be used to study the dynamic deformations not only in the elongated containers but in containers with commensurable quantities of its specific dimensions, too. Accuracy regarding the main natural frequency will be satisfied (with error about 1 %) when the length of the container is two times greater than a specific dimension of a cross section. Conditions of the rational models of deformation vibrations of containers are presented in a graph form that is comfortable in engineering practice.

Bandwidth enhancement in an InGaN/GaN three-section superluminescent diode for optical coherence tomography

In this paper, the optoelectronic properties of InGaN-based blue (430 nm) superluminescent light-emitting diodes with a multi-section, three contact design are reported. The bias conditions of the rear absorber section and gain sections are explored in terms of enhancing and maximizing spectral bandwidth. We demonstrate that broader emission can be obtained with a short circuit, rather than an open circuit absorber section, and with two active regions at different current densities as opposed to a single active contact. Under optimal drive conditions, a −3 dB linewidth of 20 nm is obtained at 430 nm. Analysis of the device emission spectrum indicates that an axial resolution of ∼3.4 μm may be obtained in an optical coherence tomography system.

The mechanics of built-up cold-formed steel members

Abstract The paper presents methods of analysis of built-up sections in which the discrete locations of fasteners is accounted for explicitly, rather than by smearing their effect using continuous shear flexibility as in current approaches. By considering fasteners at discrete points, it is possible to analyse the effects of placing additional fasteners at the ends (end fastener groups), to account directly for actual support conditions and to determine the optimum locations of fasteners. The paper first outlines the linear analysis of beams in flexure and introduces the notion of the effective flexural rigidity to account for partial composite actions. Closed form solutions are provided for five load and end support cases to demonstrate the application of the analysis. Next, the paper describes the linear analysis of built-up sections in torsion, considering first uniform torsion followed by non-uniform torsion. Closed form solutions are obtained for the effective torsion rigidity (GJeff) of built-up sections featuring closed loops. A framework is also presented for determining the effective torsion rigidity (EIw,eff) of open built-up sections in non-uniform torsion. The paper concludes with the analysis of built-up sections subject to flexural buckling. A general variational buckling equation is derived followed by an energy-type method for calculating buckling loads for common end support conditions, including columns supported on flexible end tracks. Closed form solutions are presented for up to seven rows of fasteners longitudinally. While by nature approximate, the solutions are shown to be highly accurate. Comparisons are made between the presented closed form solutions and buckling load predictions obtained using current design provisions.

Forest stocks control long‐term climatic mortality risks in Scots pine dry‐edge forests

AbstractForest research has addressed the importance of an improved understanding of drought–stocks interactions in the dry edge of tree species range. Nonetheless, more efforts are still critically needed to link up the multiple ways by which climatic stressors can trigger tree mortality, including population‐level determinants and management. Here, we analyze the interactive effects of North Atlantic Oscillation (NAO), a surrogate of climatic variability in southwestern Europe, and forest stocks on tree mortality in dry‐edge populations of the most widespread Eurasian tree species, Pinus sylvestris L., in the forest of Valsaín (central Spain). Specifically, we use tree mortality data gathered since 1941 in six multiannual periods. Results suggest that the main mortality risks in these forests can occur either in positive or negative NAO phases, but that their relative impacts are critically mediated by forest structure. In NAO+ periods, commonly associated with warm–dry conditions in the Iberian Peninsula, a peak of mortality was found in closed forest sections, whereas the second peak, found in open forest sections, was related to NAO‐ periods, correlated with temperate‐rainy weather conditions. This finding reinforces the key role of management—through its control on forest structure—as a driver of forest vulnerability to climate. Accounting for the multiple ways in which stocks modulate tree responses to different risks emerges as a critical element when it comes to the design of efficient adaptation measures in managed dry‐edge forests.

Stimulation experiment of horizontal wells filled with permeable and water-blocking gravel in deepsea bottom-water gas reservoirs

In order to find an economic and effective water control method for horizontal wells in deep sea bottom-water gas reservoirs, we prepared modified coated gravel. Based on this, wear resistance, temperature resistance and water plugging capacity (WPC) tests were carried out on the coated gravel. Then, experiments were carried out using the 3D simulation device for the development of large-scale bottom-water gas reservoirs to compare the development effects of horizontal wells packed with conventional gravel and coated gravel in deepsea bottom-water gas reservoirs. And the following research results were obtained. First, the upper limit of temperature resistance of the gravel coating is 240 °C and the gravel packing speed can reach 4.48 m/s, which is 8 times the average flow velocity of gravel packing in actual open hole sections. Second, as the permeability of the coated gravel packing layer increases, its WPC gets weak. When the permeability is lower than 1500 mD and the displacement pressure difference is lower than 0.6 MPa, the WPC of the coated gravel packing layer is between 0.17 and 0.68. Third, the coated gravel layer functions as gas permeability and water plugging, so the horizontal well technology with coated gravel packing can reduce the flow capacity of water phase breaking into the dominant flow passage, so as to delay the rise of water production of gas well and prolong the gas production time. In this way, the gas recovery factor of bottom-water gas reservoir can be increased effectively. In conclusion, this technology has the function of spontaneous selective water plugging, i.e., “water plugging in case of water and gas permeability in case of gas”, and its technical and economic advantages are remarkable, which can provide a new idea for the water-control development of deepsea bottom-water gas reservoirs.

Design and qualification of an unsteady low-speed wind tunnel with an upstream louver system

The design and qualification of a longitudinal gust generator in a low-speed, blow-down, open-return wind tunnel was conducted. Flow-impeding louvers were used to rapidly change the blockage ratio at the inlet, effectively reducing test section flow speeds up to $$60\%$$ and $$52\%$$ for the closed and open test section configurations of the wind tunnel, respectively. The wind tunnel responds more quickly for higher fan speeds, shorter tunnel lengths, and during louver closing motions (deceleration). A mathematical model developed to predict the wind tunnel’s response shows these same trends and agrees with the experimental data to within 0.03 in amplitude ratio and $$4.3^\circ$$ in phase lag, for all cases studied. Comparison of the closed to open test section configurations reveals that flow disturbances propagate nearly instantaneously, or in a globally unsteady manner, within the closed configuration, while they convect at speeds similar to that of the mean flow when testing in the open configuration.

Squeeze Cementing Using Braden Head Squeeze Method On ‘Dsr-29’ Well Tarakan Field PT. Medco E&P Indonesia

Squeeze cementing is an operation in which a cement slurry is pressed to a certain pressure on an oil or gas well. The purpose of doing squeeze cementing is to block water or gas flow and oil zones, close certain zones to produce other productive zones, repair damaged casing, and as a continuation of primary cementing work. Squeeze Cementing is done when workover a well. Workover and well service operations in a well, is a type of activity in the oil industry aimed to maintain wells so that they can continue to produce optimally and increase productivity back wells due to production problems. Squeeze Cementing Project on Tarakan field, DSR-29 well serves to block perforation that is no longer needed or open hole section at a depth of 630 - 635 m (670 MZ) so that a reservoir can be isolated and the casing can be firm or strong against pressure. Squeeze cementing method used in the well is the Braden Head Squeeze method. In the middle of workover process, there are problems such as existence of remaining perforating gun, and gas traps. Certain procedure is applied so that the cementing process has been carried out successfully.

QCD predictions for open charm meson production at the LHCb in a fixed-target experiment

We investigate open charm meson production in fixed-target LHCb experiment at $\sqrt{s}=86.6$ GeV in $p+^4\!\mathrm{He}$ collisions. Theoretical calculations of charm cross section are done in the framework of the $k_{T}$-factorization approach. Its application in the kinematical range never examined before is carefully discussed. We consider different schemes for the calculations relevant for different unintegrated (transverse momentum dependent) parton densities in a proton. We include in the analysis both CCFM- and DGLAP-based models of unintegrated parton distributions appropriate for the considered kinematics. Integrated as well as differential cross sections as a function of $D^{0}$ meson rapidity and transverse momentum are shown and compared with the experimental data. As a reference point, predictions of next-to-leading order collinear approach are also presented and discussed. A very good agreement between the experimental data and the $k_{T}$-factorization predictions was obtained. Both the CCFM and the DGLAP-based frameworks for parton distributions in a proton are successfully used to explain the LHCb fixed-target open charm cross section.

Dynamic Response Analysis of Open Section Structures with Warping Restraint Conditions and Impact Load Durations

The response analysis of frame structure with open section beams considering warping conditions and short duration load have been performed. When a beam of frame structure is subjected under torsional moment, the cross section will deform a warping as well as twist. For some thin-walled sections warping will be large, and accompanying warping restraint will induce axial and shear stresses and reduce the twist of beam which stiffens the beam in torsion. Because of impact or blast loads, the wave propagation effects become increasingly important as load duration decreases. This paper presents that a warping restraint in finite element model effects the behavior of beam deformation, dynamic mode shape and response analysis. The computer modelling of frame is discussed in linear beam element model and linear thin shell element model, also presents a correlation between computer predicted and actual experimental results for static deflection, natural frequencies and mode shapes of frame. A method to estimate the number of normal modes that are important is discussed.

The Influence of the Layer Arrangement on the Distortional Post-Buckling Behavior of Open Section Beams.

The paper deals with the design of the stacking sequence of layers in the laminate beams with open-cross sections in order to create the desired behavior in the post-buckling range. Laminate beams with channel and lipped channel cross-sections made of glass fiber reinforced polymer (GFRP) laminate with different layer arrangements (symmetrical and nonsymmetrical) have been considered. In case of the nonsymmetrical stacking sequences, hygro-thermally curvature stable (HTCS) laminates have been taken into account. Pure bending was assumed as the type of load. In the case of beams with open cross-sections, this load type can cause the lateral-distortional buckling mode. A parametric study was performed to analyze the influence of layer arrangement on post-buckling behavior. The finite element method was used to developed numerical models and conduct simulations. Additionally, the experimental tests of the channel section beams were performed in order to validate the developed numerical models.

Axial crushing of self-lock multi-cell tubes with foam filler and tube envelope

A type of self-lock multi-cell tubes assembled by open section components is recently proposed to serve as energy absorbing devices. Due to the open feature of the section, the self-lock tubes with large width may develop global buckling mode under axial crushing and show much worse energy absorption performances. To overcome this drawback, expanded polystyrene (EPS) foam fillers are firstly employed to improve the stability of the structural deformation and to increase the energy absorption efficiency. Experiment results show that a 4% increase in mass by EPS foam leads to about 20% increase in energy absorption of the self-lock tube. Numerical analyses are also carried out to simulate the tests and analyze the structures with other enhancement methods including Al foam filling and tube enveloping. They may be employed separately or simultaneously. The combination method of Al foam filling and tube enveloping gets the highest energy absorption capacity and efficiency. Theoretical analysis is performed to predict the mean crushing force of self-lock tubes enhanced by Al foam filling and tube enveloping, and the theoretical results compare well with numerical results. Finally, crashworthiness optimization problems are proposed and solved to explore the optimal enhancement configurations of the self-lock multi-cell tubes.

Experimental study and mathematical modeling on the unsteady galloping of a bridge deck with open cross section

Galloping instability can potentially threaten the modern launching of steel-concrete composite bridge girders, due to light weight and bluff shape of the steel box, which is normally launched first. A bridge deck with typical open cross section was selected and investigated in smooth flow through wind tunnel techniques. Aeroelastic tests showed that the classical instability arising from the interaction between vortex-induced vibration and galloping may occur for a mean flow incidence of 4°, fixing the actual galloping onset at the Kármán-vortex-resonance wind speed up to a high value of the mass-damping parameter. In contrast, a different and more complicated behavior was observed for a mean flow incidence of 0°, where the actual galloping instability occurs at a wind speed clearly higher than the Kármán-vortex-resonance wind speed even for a very low value of the mass-damping parameter. Static tests further indicated that the most evident difference between the two cases is the magnitude of the vortex shedding force, which is much lower for a null angle of attack. A rectangular cylinder with the same side ratio was also tested for the sake of comparison. Finally, Tamura’s wake-oscillator model was implemented for the bridge deck at a mean flow incidence of 4°, following a recently proposed parameter identification method. The mathematical model was found to be able to give some promising predictions even for a complex bridge deck profile.

Characterisation of fractured carbonate aquifers using ambient borehole dilution tests

Fractured carbonate aquifers derive their transmissivity essentially from a well-developed network of solutionally-enhanced fractures and conduits that can lead to high groundwater velocities and high vulnerability to contamination of water quality. Characterisation of the variation of hydraulic properties with depth is important for delineating source protection areas, characterising contaminant fate and transport, determination of the effectiveness of aquifer remediation, and parameter estimation for models. In this work, ambient open borehole uniform and point injection dilution tests were conducted on observation boreholes in the unconfined Cretaceous Chalk aquifer of East Yorkshire, UK, and interpreted in conjunction with other data via the implementation of a new work flow. This resulted in the characterisation of flow in these boreholes and the inference of properties such as groundwater flow patterns and velocities in the surrounding aquifer formation. Our workflow allowed sections of open boreholes showing horizontal versus vertical flow to be distinguished, and the magnitude of such flows and exchanges with the aquifer to be determined. Flow within boreholes were then used to characterise: i) presence and direction of vertical hydraulic gradients; ii) nature and depth distribution of flowing features; iii) depth interval porosity and permeability estimation of the flowing features from overall borehole transmissivity and geophysical image or caliper logs; iv) groundwater velocity estimation in the surrounding aquifer. Discrete flowing features were distributed across the range of depths sampled by the observation boreholes (typically up to 45–60 mbgl), but the majority were located in the zone of water table fluctuation marked by solutionally enlarged flow features. Quantitative interpretation of both uniform injection (tracer distributed throughout the open borehole section) and point injection (slug of tracer introduced at targeted depth) yielded vertical velocities within the borehole water column in broad agreement with those measured by flow logging. Depth specific fracture kinematic porosities inferred from the ambient dilution data combined with long-interval pump test and geophysical log data ranged between 3.7 × 10−4–4.1 × 10−3 with an average of 2.1 × 10−3; these values were in excellent agreement with those from other methods applied to the same aquifer such as larger scale pumping tests. A new approach to estimation of groundwater velocities from the dilution test data using externally measured hydraulic gradients gave inferred horizontal groundwater velocities ranging between 60 and 850 m/day, in full agreement with those from previously conducted borehole-to-borehole tracer tests. These results confirm that the studied aquifer is karstic, with rapid preferential pathways which have implication for flow and transport modelling, and pollution vulnerability. Our study results indicate that ambient single-borehole dilution approaches can provide an inexpensive and reliable approach for the characterisation of fractured and karstic aquifers.

Analysis on the damage causes of sabo dam with one open cross section at upstream of Fuxing bridge in Lacus Creek

Lacus Creek is one of the important tributaries of the Laonong River upstream of the Gaoping River, which is an important river in southern Taiwan. After Typhoon Morakot in 2009, severe sediment disasters occurred, which affected the security of local revitalization, and the government has since invested in numerous projects to reduce the impact of sediment and flood disasters. In 2017, the Kaohsiung City government built a sabo type dam upstream of Fuxing Bridge in Lacus Creek; however, it was severely damaged by a heavy rain less than a year later. To investigate the cause of the damage, site investigations, concrete sampling tests, hydrology analysis, and reviews of the planning and design methods, construction process, etc. have been conducted, in order to understand the cause of the problem, avoid repeating mistakes, and clarify the responsibility of the administrative agency. The investigation and research found that many recent cases of torrent management have considered the transverse structures as isolated wildlife corridors, reduce the height of the transverse structures, create gentle slopes of the downstream surfaces, add fish passages, cut (openings) export slits, etc.; however, after setting up these environmentally friendly facilities, their effect and impact have not been explored in depth. This research survey found that, although the frequency of heavy rain events is not high in recent years, the current iterative impact of continuous rainfall may exceed the original design requirements. If the overflow mode with a single export opening is added, the scouring energy will be concentrated, and this additive effect is likely to cause the foundation of the sabo dam to lose bare space, and finally, the dam will be damaged. Therefore, it is recommended that when designing these torrent transverse structures, try to avoid using the method of a single narrow opening: it is better to increase the number of export openings (like a slit dam), expand the size of a single export opening, or adopt a fully enclosed dam design.

Design and application of well cementing technology based on the precise managed pressure balancing method in narrow pressure window hole sections

In the Sichuan Basin, the drilling of complex deep and ultradeep wells is restricted by the casing sequence. Multiple pressure systems are usually encountered in the same open hole section, and narrow safety density window is observed in vertical strata. The application of managed pressure drilling (MPD) technique which is often used in well drilling ensures the safe and efficient drilling, but it also brings about great challenges to the small-gap liner cementing at the lower part. Therefore, it is of great practical significance to research a cementing technology that can not only satisfy the quality requirement of small gap liner cementing, but also ensure the safe cementing in the strata with narrow safety density window. In this paper, a cementing technology based on precise managed pressure balancing method was proposed by referring to the successful application of MPD technique. According to the cementing design, the hydrostatic column pressure of annulus fluid is under-balanced (slightly lower than the formation pore pressure), and then a precise managed pressure drilling device is adopted to produce back pressure through wellhead restriction or apply wellhead compensation pressure, so that the balanced pore pressure can be reached in the process of cementing via the wellhead pressure and the flow friction of fluid in the annulus. After the cementing is completed, a certain compensation pressure is applied to the annulus continuously to prevent annulus channeling during waiting on cement caused by insufficient static pressure and slurry weight loss. After this technology was applied to an ultradeep exploration well in the Sichuan Basin, the qualification rate of borehole cementing quality reached 97%, and the well sections with good cementing quality accounted for 76%. In conclusion, this technology needs no additional equipment, and only by virtue of the MPD equipment, it can achieve safe cementing construction and cementing quality improvement under high displacement efficiency.

Development of Autonomous Advanced Disinfection Tunnel to Tackle External Surface Disinfection of COVID-19 Virus in Public Places.

This paper describes a robust autonomous disinfection tunnel to disinfect external surfaces of COVID-19 virus such as clothes and open body sections in public places such as airports, office complexes, schools, and malls. To make the tunnel effective and highly efficient, it has been provided with two chambers with three disinfection processes. Due to the multiple processes, the possibility of neutralizing the virus is quite high and higher than other solutions available at this point for this purpose. Chamber 1 sprays the solution of a disinfectant on the person. This solution can be either a dilute solution of approved chemical or any Ayurvedic/herbal disinfectant. Once the person enters chamber 2, he/she is exposed to hot air at 70 °C along with far-ultraviolet C rays (207–222 nm). Both chambers function autonomously by detecting a person in a chamber using ultrasonic sensors. The proposed tunnel is developed under industry–academia collaboration jointly by Technopark@iitk and ALIMCO under the ambit of the Ministry of Human Resources Development and the Ministry of Social Justice and Empowerment, respectively. The tunnel is referred to as the ‘Techno Advanced Disinfection Tunnel’ (TADT).