Search

Generally, geothermal fields in Indonesia are situated in the mountains, forests, and remote area. The surface area, access, environment, license, and permit are limited, so that from a permitted well pad many wells are designed directionally to reach the reservoir. Directional drilling in geothermal wells is challenging due to hard volcanic rocks, the presence of vugs or cavern, and high temperatures leading to massive lost circulation, drilling break, and the difficulty to turn and control the direction stably during drilling. These cause a critical condition reducing the wellbore quality: high Dogleg Severity (DLS), tight hole, and stuck pipe occurrence. Besides, this leads to higher stress and strain experienced by the casing or liner and causes yield strength reduction and failure. Thus, it is essential that the directional drilling design and operation, particularly trajectory, be optimized. This research summarized methods to evaluate the actual drilling operation and wellbore condition of wells in Dieng Field. The result is useful to identify the critical conditions caused by drilling and formation problems setting the maximum load limitations of the design and subsequent operation. It is recommended that buckling analysis, full-scale testing, and several design and operation scenarios be conducted prior to the drilling operation.

During cementing operation with oil-based drilling fluids, the casing and well wall are in the "oil wet" environment, and the cement slurry cannot achieve good cementation with the second interface, which seriously affects the cementation quality of the cementing interface. Therefore, it is very important to select a flushing fluid with good performance and high flushing efficiency for cementing operation with an oil-based drilling fluid. An integrated measurement system of interface parameters and a rotating liquid interface tension tester is selected in the room. A set of evaluation methods of wetting reversal is developed to evaluate the wetting reversal ability of type A and type-B flushing fluids on site to optimize the reasonable type and concentration of the flushing fluid. The experimental results show that under the same concentration, the surface tension and interfacial tension of type A flushing solution are lower than those of type-B; that is, the hydrophilic effect of type A flushing solution is better than that of type-B. The wettability reduction of type A is better than that of type-B. The wetting reversal ability of type A flushing solution with a surfactant concentration of 30% is better than that of type-B. The evaluation methods include surface tension, interface tension, dewetting ability, and oil washing ability of the flushing fluid, and the evaluation of the wetting reversal ability is carried out on the basis of the sandstone, sheet metal (steel for three open casings on site), and slide glass (as a reference). Then, according to the optimal concentration of the flushing fluid, a mixing experiment of the two kinds of flushing fluids is carried out to evaluate the ability of wetting reversal, and compared with the experimental results of A and B, the reasonable flushing fluid formula is finally selected. A proper analysis of the adaptability of the evaluation method of the flushing fluid is conducive to the reliable evaluation of the performance of the flushing fluid and the enhancement of the operator's ability to grasp the cementing quality. To guide the field practice has a very important practical significance, but it also has a guiding role for the development of new pre-liquid products.

With the rapid development of shale gas exploration and development in China, casing deformation in shale gas horizontal wells happens frequently, which directly impacts the development efficiency and benefits of shale gas. In order to explore casing deformation prediction, prevention and treatment methods, this paper analyzes the geological and engineering causes of casing deformation in shale-gas horizontal wells through laboratory work, such as the casing resistance to internal pressure alternating test, the ground simulation test and systematical casing deformation characteristic analysis of MIT24 caliper logging, and the large-scale physical simulation test and numerical simulation of casing deformation. Then, combined with the generalized shear activity criterion, a new method for evaluating casing deformation risk points and some technical measures for preventing casing deformation were formulated. And the following research results were obtained. First, the deformation characteristics of 119 casing deformation points in 23 wells interpreted by MIT24 caliper logging are consistent with the mechanical behaviors of shear compression deformation test. Second, the large-scale physical simulation test shows that natural fault-fractures slip obviously under the state of strike-slip stress. Third, numerical simulation shows that the compression stress on casing increases with the increase of fault-fracture slip. When the fault-fracture slip is between 7.5 mm and 9.0 mm, the casing reaches the critical yield strength and begins to undergo plastic deformation. The “temporary fracture plugging + long segment and multi-cluster” and other technologies are field tested in 28 wells in Weiyuan area of southern Sichuan Basin. The casing deformation rate decreases from 54% (before this research) to 14.3%, and the segment loss rate decreases from 7.8% to 0, which reveals remarkable achievements in casing deformation treatment. In conclusion, the shear slip of fault and macro fractures (referred to as fault-fracture) is the main cause of casing deformation in shale gas horizontal wells, and some measures (e.g. “temporary fracture plugging + long segment and multi-cluster”, reducing fracturing scale and releasing wellbore pressure properly) shall be taken in advance to reduce the fault-fracture activity before the risk point of casing deformation is fractured, so as to reach the goal of casing deformation prevention.

Актуальність роботи полягає в тому, що виникають пошкодження обшивки фюзеляжу і ці пошкодження необхідно ремонтувати. Робота полягає у тому, що за допомогою використання комп’ютерної моделі вдалося визначити діючі навантаження на пошкоджену частину обшивки літака. А потім за цими значеннями було спроектовано і розраховано ремонтну деталь. Об’єктом дослідження в даній роботі вибрано пошкодження обшивки фюзеляжу літака в зоні завантаження багажу, де найбільш часто виникають пошкодження між 58 і 59 шпангоутами і між 37 та 38 стрінгерами. За мету роботи було покладено створення ремонтної накладки для пошкодженої частини літака, що витримає усі діючі навантаження. Задачами даної роботи є визначення напружено-деформованого стану обшивки у пошкодженій зоні, розрахунок і створення найкращої конфігурації ремонтної накладки і технології її встановлення, так щоб вона витримала усі навантаження. The relevance of the work is that there are damages to the fuselage skin and these damages must be repaired. The work consists in the fact that with the help of the use of a computer model, it was possible to determine the effective loads on the damaged part of the aircraft skin. And then, based on these values, the repair part was designed and calculated. The object of research in this work is damage to the fuselage skin of the aircraft in the baggage loading area, where damage occurs most often between the 58 and 59 frames and between the 37 and 38 stringers. The goal of the work was to create a repair pad for the damaged part of the aircraft that would withstand all the current loads. The tasks of this work are to determine the stress-deformed state of the cladding in the damaged area, to calculate and create the best configuration of the repair overlay and its installation technology, so that it can withstand all loads.

In the literature, the effect of the type of casing on fermented sausages is quite unexplored, while several studies are focused on the impact of starter cultures. Therefore, this paper studied the effect of three commercial starter cultures and two casings (natural or collagen) on Italian fermented sausages. Physico-chemical parameters (aw, pH, weight loss), microbiota, aroma profile and sensory analysis were evaluated. Results showed that collagen casings promoted a higher reduction of pH and weight loss. Concerning the microbiota, samples with natural casing had higher counts of lactic acid bacteria, while yeast proliferation was promoted in those with collagen. Regardless of the starters and casings applied, levels of enterococci and Enterobacteriaceae were low (≤2 log CFU/g). The aroma profile was significantly affected by casing: despite the starter applied, the presence of collagen casing favoured acid accumulation (mainly acetate and butanoate) and reduction of ketones. Sensory analysis highlighted significant differences only for odour, colour intensity and sourness. The differences observed suggest that collagen casings may provide a greater availability of oxygen. Overall, casings rather than starter cultures impact the microbial and sensorial features of fermented sausages.

Hydraulic fracturing has been widely used in the petroleum industry for exploiting tight and ultra-tight formations. Although conventional hydraulic fracturing techniques have advanced significantly over time, it is still challenging to achieve separate intervals within multilayered formations, target the right layers and accurately fracture in succession. Hydra-jet-assisted fracturing, which involves boosting pressure in the cavity behind the casing to enable successful fracture initiation, is a technique often practiced to overcome this. However, there exists limited research regarding the pressure field within the cavity; therefore, this study aims to establish a mathematical model for predicting boosting pressure in the cavity under various reservoir conditions. In this paper, the authors present a numerical model to investigate the effects of nozzle differential pressure ratio of nozzle diameter to cavity diameter, annulus pressure and cavity length on boosting pressure. It is observed that the boosting pressure increases linearly with nozzle differential pressure and diameter ratio, respectively, while retaining other parameters as constant. However, simulations also indicate that annulus pressure and cavity length have minimal effect on the boosting pressure. In addition, the relationship between the boosting pressure coefficient and dimensionless standoff distance is also developed for specific diameter ratios, along with an insightful sensitivity analyses. A mathematical model is established to predict the final boosting pressure at different diameter ratios. As a result, this advances understanding of the design of treatment parameters in hydra-jet-assisted fracturing. Furthermore, this investigation is another step forward toward the global application of hydra-jet fracturing technology in developing deeper and layered tight gas sands.

The autocorrelation function is combined with wavelet transform and cyclostationary theory (WT-AF-CT) in place of threshold denoising, and meanwhile the mean power ratio (MPR) is calculated by the proposed method. Furthermore, extracted characteristic as well as calculated MPR is used to identify compound faults of rolling bearings in aero-engine based on casing vibration acceleration signal-including the ones of common rolling bearing (inner race rotates and outer race is constant) and intershaft bearing (co-rotates with outer and inner race). A comparative analysis was carried out between conventional researches (cyclostationary theory (CT) or wavelet transform combined with threshold value denoising (WT-TD)) and proposed WT-AF-CT method. Additionally, the effect of sensors installation direction for feature separation and extraction of compound faults is considered. The results indicate that the proposed WT-AF-CT method can separate and extract characteristics of compound faults exactly and identify fault types of bearings precisely, no matter sensors are installed horizontally or vertically, while CT or WT cannot.

The analysis of works on identification of causes of deformation of casing production strings of wells is carried out. The main reason for the deformation of the strings is the technogenic deformation of the rocks of the layers of drained deposits. The need to take into account technogenic processes for the design of used wells at the design stage of oil and gas field development is shown.

In the modern turbo-machinery, reducing the clearance between the blade tip and casing inner face is an effective method to improve the power performance, but the clearance reduction leads to increased risk of blade-casing rubbing. In this paper, a blade-coating rubbing force model which considered the abradable coating scraping is developed to simulate the rotor system dynamic characteristics at blade-casing rubbing faults with abradable coating. An experimental tester is established to simulate the rotor system blade-casing rubbing faults; the AlSi-ployphenyl ester abradable coating is prepared and introduced into the blade-casing experiment to verify the model. After the vibration and force analysis in simulation and experiment, the dynamic characteristics and the influence factors of blade-casing rubbing rotor system are studied.

In the petroleum industry, packers refer to the components/products which are used to isolate one section in a formation from others, or to isolate the outer section of a production tubing from the inner section, which may be a casing or a liner or the wellbore itself. Mechanical packers are installed through some form of tubing movement. Permanent packers are low in cost and provide better seal. Retrievable packers have lower sealing capability but are re-usable after repair, and therefore expensive. More innovative packers made of swellable elastomers are rather new. These elastomers swell when they come in contact with different types of fluids (mostly water and oil). Like a casing, these new packers are lowered to the desired depth and allowed to swell before production or injection operations begin. Various studies have been published about the swelling and mechanical response of these elastomers. However, many questions remain about the sealing performance of swell packers, and their effectiveness in actual wellbores of rough and random profiles. This paper describes the design and development of an experimental unit for performance testing of a mix of inert and swelling elastomer seals under realistic well conditions. Actual swell packers and petroleum tubulars are housed in a concrete block that replicates open-hole and cased-hole wells through layers of varying roughness. This is a one-of-its-kind unit providing full-scale demonstration about the working of swell packers against outer casing or rock formation in a wellbore. It is also a complete testing apparatus to investigate the behavior of swell packers made of fast-swell and medium-swell elastomers, and how they seal off irregular boreholes. This work can provide basic understanding and visual corroboration to petroleum engineers and students, swelling elastomer application developers, and academic and research personnel.

With the rapid development of aero-engine manufacturing technology, the dual-rotor system has been employed in part of turbofan engine in order to improve the working performance of aircraft more efficiently. In this study, taking the counter-rotation dual-rotor as the research object, the dynamic model of dual rotor-casing coupling system is established by the aid of MATLAB. The dynamic frequency curves are in good agreement with the results in references and calculated by FEM method, that shows the validity and feasibility of the model. The local rub-impact dynamic model of dual rotor-casing coupling system is established, and rubbing analysis is carried out using Newmark- β method. The effects of rotating speed and speed ratio on local rub-impact response are deeply discussed. The results show that with the increase of rotating speed, combined frequencies and frequency multiplication components are more significant. In addition, speed ratio has a great influence on the periodic motion of the system. With the increase of the absolute value of the speed ratio, the whirl radius of the outer rotor and the normal rubbing force increase dramatically.

Multistage fracturing is the main means of shale gas development, and casing deformation frequently occurs during fracturing of shale gas horizontal wells. Fracturing fluid entering the formation will change in situ stress nearby the wellbore. The changes of in situ stress are mainly reflected in the following two aspects: one is the increase of in situ stress and the other is the nonuniformity of in situ stress along the wellbore. And it is for this reason that the production casing is more likely to collapse under the nonuniform in situ stress load. According to the service conditions of production casing in shale gas reservoir, this paper studied the casing deformation and the collapsing strength subjected to the nonuniform loading by the experimental and numerical simulation method. The results show that under the condition of nonuniform loading, (1) the diameter variation rate of the casing reduces with the increase in the ratio of sample to tooling length. When the ratio is less than 3, the casing collapse strength will be significantly reduced. And when the ratio is greater than 6, the impact of sample length on casing collapse strength can be ignored. (2) The increase in the applied loading angle will decrease the diameter variation rate. When the loading angle increases from 0° to 90°, the critical load value increases from 1600 kN to 4000 kN. (3) The increase in load unevenness coefficient will rapidly decrease the casing collapse strength. When the load unevenness coefficient n is 0.8, the casing collapse strength reduces to 60%, and when the load unevenness coefficient n is 0, the casing collapse strength reduces to 28%. The findings of this study can help for better understanding of casing damage mechanism in volume fracturing of shale gas horizontal well and guide the selection of multistage fracturing casing type and fracturing interval design.

Losses induced by tip clearance limit decisive improvements in the system efficiency and aerodynamic operational stability of aero-engine axial compressors. The tendency towards even lower blade heights to compensate for higher fluid densities aggravates their influence. Generally, it is emphasised that the tip clearance should be minimised but remain large enough to prevent collisions between the blade tip and the casing throughout the entire mission. The present work concentrates on the development of a preliminary aero-engine axial compressor casing design methodology involving meta-modelling techniques. Previous research work at the Institute for Turbomachinery and Flight Propulsion resulted in a Two-Dimensional (2D) axisymmetric finite element model for a generic multi-stage high-pressure axial compressor casing. Subsequent sensitivity studies led to the identification of significant parameters that are important for fine-tuning the tip clearance via specific flange design. This work is devoted to an exploration of the potential of surrogate modelling in preliminary compressor casing design with respect to rapid tip clearance assessments and its corresponding precision in comparison with finite element results. Reputed as data-driven mathematical approximation models and conceived for inexpensive numerical simulation result reproduction, surrogate models show even greater capacity when linked with extensive design space exploration and optimisation algorithms.Compared with high-fidelity finite element simulations, the reductions obtained in computational time when using surrogate models amount to 99.9%. Validated via statistical methods and dependent on the size of the training database, the precision of surrogate models can reach down to the range of manufacturing tolerances. Subsequent inclusion of such surrogate models in a parametric optimisation process for tip clearance minimisation rapidly returned adaptions of the geometric design variables.

This paper considers effects of Rotating Inlet Distortion (RID) on a two-stage axial compressor and the stabilization effects of a casing treatment subjected to the considered RID. In multi-spool engines, the downstream compressor suffers a RID when the upstream fan/compressor is in rotating stall. A controlled rotating sectional screen upstream of the compressor was adopted to generate the RID in different intensities, and co- or counter spinning direction compared with the rotor. The response of the compressor to inlet distortion was interpreted as the changes of stall margin. Results show that there are two peaks for the stall margin degradation where the distortion screen rotates near 20% and 70% of the rotor’s rotational frequency, respectively. Based on the measurements taken during the pre-stall process, it is suggested that the two frequencies are associated with the eigen frequencies of the compressor. Specifically, the first is associated with a stall precursor that is suspected as an initial disturbance existing in compressor and the second is related to a spike-type stall precursor. At last, a kind of Stall Precursor-Suppressed (SPS) casing treatment was applied to enhance the compressor stability in RID conditions. The result indicates that the stall margin is improved by 6% at an average level and there is nearly no efficiency loss caused by the application of such casing treatment.

A structure’s material plasticity influence on the pattern of contact interaction of its elements during operation is studied. The stress-strain state problem for the inner casing of a steam turbine high-pressure cylinder operating at supercritical steam parameters (over 240 atm and 565 °C) is solved. The problem is solved by using a finite-element software package. A model of thermoplasticity with kinematic and isotropic hardening is considered. In carrying out the study, experimental strain curves were used for the materials of the connection. The main dependencies used in solving the problem are given. The method of solving the thermal contact problem of interaction of flange connector elements in the conditions of plasticity is based on the application of a contact layer model. To be able to take into account changes in the load from the fastening in the process of combined strain of both the fastening and the casing, first proposed is a method of the three-dimensional modeling of the thermal tightening of the fastening of the horizontal casing connector by applying the linear coefficient of linear expansion of the material. The proposed approach allows modeling the stress of the initial tightening of studs by specifying a fictitious change (decrease) of the coefficient of linear expansion of a stud given as a separate body in the calculation scheme. The magnitude of the specified change in the coefficient of linear expansion is determined from the relationship between the stress of the initial tightening in the stud and the required, for its creation, elongation, which is implemented in the calculation scheme in the presence of different values of linear expansion of both the stud and the casing. To conduct the numerical experiment, an ordered finite-element grid of the casing design was constructed. A 20-node finite element was used in the construction of the casing grid and the fastening. The effect of force loads and the temperature field, in which the structural element under consideration is operated, is taken into account. An analysis of the results of distribution of equivalent stresses and contact pressure during operation is carried out. The difference between the obtained results and the results of solving the problem in the elastic formulation is noted.

The artesian well of Monzoungoudo has been abandoned since 2005. The non-mastery of artesianism springing up at this water point constitutes a waste of the resource and has caused environmental damage. It is a question of an uncontrolled flow of the artesian well induced by the depressurization of the aquifer, resulting in a potential loss of capacity of neighbouring wells and continuous flow of the well at the mouth of its casing. In contact of the recovered water with the surrounding soil, it may generate local flooding, gullying, soil subsidence, the formation of sinkholes and cause damage to the infrastructures located nearby. In addition, the water from the artesian aquifer on the surface migrates to the Monzoun River, while transporting suspended particles or contaminants encountered on its path. The receiving environment of this water could then be affected by an input of turbid water or various contaminants. All these reasons justify the validity of this study, which proposes to address the technique of plugging the abandoned artesian wells of Monzoungoudo in order to stop or control the gushing water. Keywords: Abandons; Artesian well; Captive aquifer; Gushing; Monzoungoudo; Shutter.

The detonation of an energetic material (EM) is manifested in the form of blast wave, fragmentation of casing material, and thermal effects. These effects are very destructive and cause injuries-being fatal-and structural damage as well. The attenuation of these effects is a prime focus. C4 explosive weighing 104 g was tested as surface burst. Peak overpressures of 1362 kPa and fireball radius of 0.65 m were measured. A multi-layer container comprised steel liner, Kevlar woven fabric, and laminated glass fiber reinforced polymer (GFRP) was developed and investigated to counter the combined blast, fragmentation, and thermal effects of EM detonation. Commercially available shaving foam was characterized and used as filling material inside the container. The foam bubbles have shown a good stability with time. The shaving foam quenched the fireball and afterburning reactions owing to rapid heat and momentum transfer mechanism. The containment system provided more than 80% overpressure reduction with respect to an equivalent open-air detonation and also restricted any escape to lateral directions. Coupled Euler-ALE (Arbitrary Lagrangian-Eulerian) approach was employed to numerically simulate the blast wave parameters. A good agreement is obtained between the simulation and experimental results.

Modern low-pressure turbine engines are equipped with casings impingement cooling systems. Those systems (called Active Clearance Control) are composed of an array of air nozzles, which are directed to strike turbine casing to absorb generated heat. As a result, the casing starts to shrink, reducing the radial gap between the sealing and rotating tip of the blade. Cooling air is delivered to the nozzles through distribution channels and collector boxes, which are connected to the main air supply duct. The application of low-pressure turbine cooling systems increases its efficiency and reduces engine fuel consumption.

This work is performed to improve or strengthen the soil in the permafrost region under building foundations or engineering structures in the conditions of the Far North. Freezing in winter and partial thawing in summer of the surface layer of permafrost are analyzed. According to the surveys on soil temperature, thawing of permafrost soils is predicted. Promising solutions are considered for the permafrost soil stabilization. The latest design solutions and developments are presented for the creation of many systems and devices for thermal stabilization of permafrost soils. A schematic diagram is suggested for the experimental installation for recording changes in ambient air temperatures and permafrost. The equipment is selected for studying the automated control system for the cooling process of casing pipe of the foundation pile and near-pile permafrost soil. An experimental installation is proposed to study the effectiveness of the automated control system. The model and simulation of this system is imple- mented in the SimInTech program. The automatic control system provides control for thermoelectric modules in automatic mode in order provide their best orientation in the ambient air temperature, depending on the soil temperature in the near-pile space of the foundation. A device is patented for stabilizing the frozen ground of a pile foundation with casing pipes containing a system for automated control for cooling process of the near-pile foundation.

In empty well killing, in order to save the time and cost of killing the well, the dynamic replacement method is often used to kill the well. The main problem of the dynamic replacement method for killing wells is how to avoid terrible working conditions caused by flooding, such as gas carrying fluid, killing fluid being brought to the wellhead. Based on the principle of flooding formation and the basic tenets of flooding correlation experiment and dynamic replacement method, this paper incorporates the kill fluid viscosity, surface tension, droplet diameter, inclination angle, drill pipe joint outer diameter, and drill pipe eccentricity into the calculation range and establishes a new mathematical model suitable for dynamic replacement kill. Based on the calculation results, the influencing factors of flooding are analyzed, and the following conclusions are drawn: the increase of dynamic viscosity, gas density in the well, casing pressure, well angle, the outside diameter of drill pipe, the outer diameter of drill pipe joint, and eccentricity of drill pipe can promote the occurrence of flooding; The increase of surface tension, well-killing fluid density, and casing inner diameter have an obstacle to flooding.

The first stage of GE-E3 turbine is employed to investigate effect of casing purge flow upstream rotor blade tip. Three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations and standard k-ω model are solved to obtain tip heat transfer simulations. The results reveal that: heat transfer coefficient of blade tip surface can be significantly reduced when casing purge flow is set. Tip averaged heat transfer coefficient of cases with and without swirly velocity casing purge flow decrease 3.5% and 3.4% compared with the case without casing purge flow. Compared with case which blowing ratio equals to 0.5, it can be found that averaged tip heat transfer coefficient of cases which blowing ratio equals to 1.0 and 1.5 decrease 2.3% and 1.8%, respectively. Setting blowing ratio as 1.0 can best cool tip surface without wasting cold air resources. Increasing rotating speed can induce cold air entering tip trailing region and improve local cooling effect. Flow structure inside the tip clearance are also revealed and discussed.

As a typical black-box problem, recirculating casing treatment (RCT) optimization of compressor stages is computationally intensive and time consuming, even though surrogate models are usually employed. In order to improve efficiency and robustness of the optimization, an expected-improvement (EI) based hybrid global optimization (EHGO) algorithm is developed by coupling an EI-based surrogate model with a hybrid optimization algorithm. Highly nonlinear and multiple modality mathematical tests show that the EHGO algorithm is able to create a high-fidelity surrogate model near targeted regions with less evaluated samples, and to obtain the global optimal solution simultaneously. The RCT of a compressor stage is optimized based on this algorithm. The number of CFD simulations required for obtaining an optimum solution is greatly reduced, as compared to similar studies using conventional methods. The optimization results show that the aerodynamic performance is improved over the whole speed line and the flow range is also extended. The dominant factors for the performance improvements and the enhanced stall margin are addressed by analyzing the local flow characteristics before and after optimization. It is found that those factors include: removing a larger amount of low-momentum fluid, achieving a more uniform flow of impeller passage in circumferential direction, and reducing the radial distortion of impeller inlet flow. The proposed algorithm has the potential to considerably speed up the optimization process and make the optimization much more accessible. It can be generalized to deal with other computationally intensive black-box problems, for example, turbomachinery optimization.

Indiscriminate disposal of beverage cans as waste poses a great threat to the environment, causing flooding, landfill, and blockage of drainages, leading to land pollution and sometimes accident. Hence, there is a need to design a system capable of converting these wastes into usable products. In this study, a simulation-based analytical design for aluminum recycling processing plant was carried out to ascertain the efficiency and reliability of the design before fabrication using finite element analysis (FEA) approach. The simulation results revealed a lesser maximum stress of 6.323 MPa for the furnace outer casing under the action of load with a displacement of 0.0795 mm. The stress of the machine components is less than the yield strength of the selected materials, making the machine fit and workable. The analytical results agree with the numerical analysis; hence the conceptual design is fit for fabrication based on the design analysis and evaluation. After the design analysis and simulation, the designed recycling process plant parts are found to be under negligible deflection and stress which is far below the yield strength of chosen materials.

In the process of reservoir exploration, the weak horizontal structural surface easily slips and cracks, and casing shearing often occurs during the formation process, which significantly affects the economic viability and effective development of an oilfield. Additionally, repeated damage at the same casing position indicates the possibility of numerous cracks in the weak structural surface. In this study, we propose the geomechanical stick-slip theory to verify the above phenomenon. The stress calculation method for the weak horizontal structural surface in the upper part of the reservoir is devised under the influence of inter-regional pore pressure differences. Based on the process of accumulation-release-reaccumulation-rerelease in the formation and deformation processes, we construct the calculation model of shear stress release and slips on the cracked surface. While considering the influence of water inflow on the cracked surface, the pressure exerted on the formation stick-slip is analyzed. Then, the model was verified by the data of block X in the Daqing oilfield. The results demonstrate that under wet conditions, the maximum static and dynamic frictional stresses on the cracked surface decrease significantly, and this makes the cracked surface more prone to a greater slip degree. After the weak horizontal structural surface cracks and slips occur for the first time, the pressure difference between regions required for formation of the next slip decreases significantly. With the continuous formation of slips, the slip range gradually expands with an increase in inter-regional pressure variance. The research work in this study provides a theoretical basis for the prevention and control of casing damage in oil development zones.

The integrity of perforated liners is crucial in geothermal production wells and this should be well designed according to correct standards. The available geothermal standards, such as the New Zealand Standard, NZS2403:2015, provides a general but less detailed discussion of geothermal perforated liner system design considerations. This research aimed to improve the limitations of NZS2403:2015 by calculating and evaluating the dynamic loads of perforated liner during four phases: borehole drilling and liner installation, flow testing, stand-alone production, and production during the injection operation. The data from production well HCE29 and injection well HCE29A, Dieng Field, Indonesia, were used in this research. In every phase, perforated liner yield strength changed, and load mechanisms varied between 1.3-2.7 and 1.6–4.6 times of the actual liner burst and collapse strength, respectively, and these lead to perforated liner failure and its lifetime reduction. The calculation results, combined with the significant production decline and production casing failure, indicated the perforated liner failure. The results also showed when it was mandatory to revise operation at later phases and to conduct appropriate maintenance according to actual perforated liner condition. Furthermore, this study can be used as a basis of future wells design and operation related to perforated liner.

Cuttings accumulation in horizontal drilling of a shale gas well is one of the main reasons for high drilling torque and drag and serious backing pressure and consequently influencing the rate of penetration (ROP), so inhibiting the generation of a cuttings bed and keeping the hole clean is an important prerequisite to ensure the smooth and safe drilling of horizontal section. In order to improve the hole cleaning efficiency of horizontal sections, this paper studied the decay laws of helical flow induced by helix angles and rotation speed of a newly developed cuttings bed remover with V-shaped blades for horizontal wells and their influences on the resuspension distribution of cuttings particles by virtue of the CFD numerical simulation method and Euler–Euler binary-fluid model, combined with the theory of particle dynamics. Then, the parameters such as blade rotation speed and blade helix angle were optimized. And the following research results were obtained. First, with the increase of the rotation speed, cuttings deposit at the bottom of the annulus deflects to a certain degree. And the higher the rotation speed, the more obvious the deflection. Second, annulus pressure drop loss increases with the increase of the helix angle. And this phenomenon is more obvious when the helix angle is larger. Third, the field test results in Well Changning H25-7 of the southern Sichuan Basin show that after the application of the newly developed cuttings bed remover for horizontal wells, the drilling friction is decreased by 33 %, the tripping is smooth without sticking. And in the process of its application, no complex downhole accident happened. Obviously, it provides good hole cleaning to ensure the safe and smooth implementation of the later casing running operation. In conclusion, this newly developed cuttings bed remover can satisfy the demand of cutting bed cleaning and drilling cost reduction and efficiency improvement of horizontal wells, so it is worth popularizing and applying. What's more, it provides guidance and reference for the design of similar cuttings bed removers.

Steel bracings are one of the most widely used systems for resisting transverse loads in the design and retrofit of concrete and steel structures. This paper reports on an experimental and numerical study of the effects of core steel and the distance of the core from the casing on the behaviour of buckling-restrained braces. Laboratory models of six braces with a core made from conventional ST37 steel or ST37-n steel (softened at a temperature of 1000° using the O'Neill method) with a core–casing distance of 0, 2 or 3 mm were designed. The experimental results showed that, compared with the brace made from ST37 steel, the use of ST37-n steel resulted in a reduction of 32% in the tensile and compressive strengths of the brace. An increase in the core–casing distance in the ST37 and ST37-n braces resulted in reductions in the brace bearing capacity and energy dissipation by 26% and 52%, respectively. An increase in the core–casing distance to more than 2 mm resulted in loss of symmetry and stability of the hysteresis behaviour of the brace; in addition, distortion due to brace local buckling under pressure also intensified.

The AOV-1 well is a development well that is planned to be drilled in the “ANTARIS” Field. Based on the data obtained from the nearest well of “AOV-1” well, a casing design will be carried out, therefore it is necessary to select casing specifications. So that it can meet the requirements technically and economically. Casing design planning is the preparation of file collected from drilling prognosis, and daily drilling report so that it can be used for calculation of pressure parameters, knowing stratigraphy, lithology, subsurface data, availability of casing stock in warehouse, and planning technical calculations for casing design operations such as d-exponent calculation to determine pore pressure, pressure calculation (formation pressure, overburden pressure, fracture pressure), calculation of the load received by casing (burst load, burst load design, collapse design), determination of casing setting depth, casing grade selection for casing design, calculation of biaxial stress correction of tension and compression stress, calculation of safety factor, and finally, calculation of economics from planning casing design. 7 ” casing program grade K-55, 20 PPF, BTC at a depth of 0 - 1968.5 ft TVD with safety factor Ni = 3.83 each; Nc = 2.19; Nj = 13.54, only 1 section is performed. casing program 9/8 " Casing program with grade K-55, 36 PPF, BTC at a depth of 0 - 820 ft. TVD with a safety factor of each Ni = 9.91; Nc = 4.83; Nj = 30.06, only 1 section is performed. 13 3/8 " casing program with grade K-55, 54.5 PPF, BTC at a depth of 0 - 250 ft. TVD with a safety factor of each Ni = 63.77; Nc = 22.99; Nj = 226.73, only done 1. The total cost for casing planning is $ 57,689 or around Rp. 816,876,240 of the budget provided, which is $ 65,000 or around Rp. 920,400,000.

The wick is the most crucial element of loop heat pipes (LHPs). At present, wick materials are limited to copper, stainless steel, nickel, and so on. Little research has been carried out on new wick materials. This paper reports the fabrication of aluminum wicks and performance tests of LHPs using aluminum wicks. Experimental data show that this LHP is capable of transferring a heating load of 130 W, while the thermal resistance is only approximately 0.04 K/W. Then, the experimental data were compared with those for LHPs using a polytetrafluoroethylene (PTFE) wick. Based on the SIMPLE algorithm, a 2-D unsteady-state heat transfer model and a 2-D steady-state flow model of the wicks are established to analyze the effects of wick material, pore size and porosity on the performance of the evaporator. The experimental data for LHPs with PTFE wicks are from the literature. The simulation results show that a PTFE wick can effectively reduce heat leakage, while an aluminum wick has better temperature uniformity and a lower casing temperature. However, wicks with large porosities have lower flow resistance.

This article presents the effect of volute chamfering on the performance of a forward swept centrifugal fan. The numerical analysis is performed to obtain the performance parameters such as static pressure rise coefficient and total pressure coefficient for various flow coefficients. The chamfer ratio for the volute is optimized parametrically by providing a chamfer on either side of the volute. The influence of the chamfer ratio on the three dimensional flow domain was investigated numerically. The simulation is carried out using Re-Normalisation Group (RNG) k-[Formula: see text] turbulence model. The transient simulation of the fan system is done using standard sliding mesh method available in Fluent. It is found from the analysis that, configuration with chamfer ratio of 4.4 is found be the optimum configuration in terms of better performance characteristics. On an average, this optimum configuration provides improvement of about 6.3% in static pressure rise coefficient when compared to the base model. This optimized chamfer configuration also gives a higher total pressure coefficient of about 3% validating the augmentation in static pressure rise coefficient with respect to the base model. Hence, this numerical study establishes the effectiveness of optimally providing volute chamfer on the overall performance improvement of forward bladed centrifugal fan.