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Sushais Bandopadhyay - One of the best experts on this subject based on the ideXlab platform.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO3 perovskite, La0.2Sr0.8Fe0.8Cr0.2O3−δ (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 °C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO 3 perovskite, La0.2Sr0.8Fe0.8Cr 0.2O3-?? (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 ??C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N 2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres. ?? 2013 Elsevier Ltd.
N. Nagendra - One of the best experts on this subject based on the ideXlab platform.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO3 perovskite, La0.2Sr0.8Fe0.8Cr0.2O3−δ (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 °C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO 3 perovskite, La0.2Sr0.8Fe0.8Cr 0.2O3-?? (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 ??C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N 2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres. ?? 2013 Elsevier Ltd.
T. Nithyanantham - One of the best experts on this subject based on the ideXlab platform.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO3 perovskite, La0.2Sr0.8Fe0.8Cr0.2O3−δ (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 °C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO 3 perovskite, La0.2Sr0.8Fe0.8Cr 0.2O3-?? (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 ??C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N 2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres. ?? 2013 Elsevier Ltd.
S. Biswas - One of the best experts on this subject based on the ideXlab platform.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO3 perovskite, La0.2Sr0.8Fe0.8Cr0.2O3−δ (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 °C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres.
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Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions
Materials Research Bulletin, 2013Co-Authors: N. Nagendra, T. Nithyanantham, S. Biswas, Sushais BandopadhyayAbstract:Chromium (III) oxide (Cr2O3)-doped LaSrFeO 3 perovskite, La0.2Sr0.8Fe0.8Cr 0.2O3-?? (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a Fracture Gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N2 on the outer side of the C-ring membranes at 1000 ??C while keeping the inner side untreated. The rings were then diametrically compressed to Fracture, and the resultant Fracture morphology was analyzed with a scanning electron microscope (SEM). A Fracture Gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N 2, a mixed inter/transgranular Fracture with a predominant intergranular pattern was observed. In the middle section of the Fracture surface, a characteristic transgranular Fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular Fracture with a predominant transgranular pattern occurred. The mechanism of Gradient Fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides significant information on microstructure evolutions of tubular LSFCO membranes under graded reducing atmospheres. ?? 2013 Elsevier Ltd.
Saeed Salehi - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the Rheological Properties of Nanosilica-Reinforced Polyacrylamide/Polyethyleneimine Gels for Wellbore Strengthening at High Reservoir Temperatures
Energy & Fuels, 2019Co-Authors: Mohamed Shamlooh, Ahmed Hamza, Ibnelwaleed A. Hussein, Mustafa S. Nasser, Musaab Magzoub, Saeed SalehiAbstract:Wellbore strengthening has been introduced recently to resolve lost circulation problems by improving the Fracture Gradient and hence extending the mud window. Polymeric cross-linkable solutions sh...
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Numerical Modeling of Induced Fracture Propagation: A Novel Approach for Lost Circulation Materials (LCM) Design in Borehole Strengthening Applications of Deep Offshore Drilling
SPE Annual Technical Conference and Exhibition, 2012Co-Authors: Saeed Salehi, Runar NygaardAbstract:Abstract Lost circulation caused by low Fracture Gradients is the cause of many drilling related problems. Typically the operational practice when lost circulation occurs is to add loss circulation materials (LCM) to stop mud from flowing into the formations. To improve the treatment for lost circulation caused by low Fracture Gradients, especially designed materials in mud system are used to seal the induced Fractures around the wellbore. This operation is in the literature referred to as wellbore strengthening that has been found to be a very effective in cutting Non-Productive Time (NPT) when drilling deep offshore wells. Size, type and geometry of sealing materials are debating issues when different techniques are applied. Also the phenomenon is not truly understood when these techniques applied in different sedimentary basins. This paper presents development and simulation results of a three-dimensional Finite-Element Model (FEM) for investigating wellbore strengthening mechanism. This study also describes a procedure for designing Particle Size Distribution (PSD) in field applications. To better understand the numerical results, the paper also reviews the connection between Leak of Tests (LOTs) and wellbore hoop stress and how these LOTs can mislead in Fracture Gradient determination. A comprehensive field database was collected from different sedimentary basins for this study. Results demonstrate that the maximum attainable wellbore pressure achieved by wellbore strengthening is strongly controlled by stress anisotropy. Results also show that Particle Size Distribution (PSD) of wellbore strengthening should be designed in order to seal the Fractures close to the mouth and at Fracture tip. This will result both in maximizing hoop stress restoration and tip-screening effects. In addition this model is able to show the exact Fracture geometry formed around the wellbore that will help to optimize the sealing materials design in wellbore strengthening pills. To support numerical modeling results, near wellbore Fracture lab experiments on Sandstone and Dolomite samples were also presented. Laboratory experiments results reveal importance of rock permeability, tensile strength and fluid leak-off in wellbore strengthening applications. Introduction Narrow pore-Fracture window in deep and ultra-deep offshore environments, highly deviated wellbores and depleted formations is the most prominent drilling challenge today. Lost circulation and high non-productive time due to the tight window is the major motivation for widening operational window and using wellbore strengthening techniques. Wellbore strengthening can be defined as "a set of techniques used to efficiently plug and seal induced Fractures while drilling to deliberately enhance the Fracture Gradient and widen the operational window??. This technology has the potential to mitigate the lost circulation problem, and improve wellbore integrity to avoid well control disasters. In addition, it might reduce the number of casing strings required to drill deep water wells. Previous joint industry projects (DEA-13 and GPRI) conducted experiments to investigate lost circulation. The main finding from these projects was the ability to increase Fracture reopening pressure by using specific type and size of materials in the drilling fluid system (Morita et al., 1996a, b, and Dudley, 2001). Investigating the physical mechanism that enhances the Fracture Gradient was not truly feasible using these experiments. Therefore, a clear understanding regarding the effect of material properties (size, type and strength) of the actual sealing mechanism was never achieved but spurred continuous investigations on how drilling fluids can improve the Fracture Gradient. Table 1 summarizes the wellbore strengthening methodologies, whereby some of them differentiate in the mechanism involved, material type and strength to be used plus the necessity for tip isolation.
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A Critical Review of Wellbore Strengthening: Physical Model and Field
2011Co-Authors: Deployment Nygaard, Saeed SalehiAbstract:Lost circulation is one of the largest contributors to down time in drilling operations. Especially when drilling wells in complex geological settings or when drilling deepwater with a small tolerance between pore pressure and Fracture pressure Gradients. To prevent or mitigate wellbore losses an engineering practice referred to as "wellbore strengthening" is conducted to increase the Fracture Gradient. Wellbore strengthening relies on propping and/or sealing the Fractures with specially designed materials. Several field cases have been reported to improve Fracture Gradient by either increasing the hoop stress around the wellbore or hindering Fracture propagation. However there seems to be unclear which results can realistically be expected when conducting wellbore strengthening operations in a wellbore. The purpose of this work was twofold. First objective was to identify types of environment creating losses in the wellbore. The second objective is to investigate the physical explanation of wellbore strengthening and what can be expected results when deployed in the field. Leak off tests does not give a good indication if the leak off point represents the Fracture breakdown pressure or Fracture propagation pressure. Therefore to understand the wellbore condition, i.e. if the wellbore is fully intact or the wellbore has existing Fractures, performing extended leak off tests is required. The simulation results indicate that Fracture Gradient improvement is caused by sealing of Fractures which hinder further Fracture propagation. However the placement of loss circulation material inside the Fracture is important. To restore the theoretical maximum Fracture Gradient, given by the Kirsch solution, the Fracture has to be sealed off close to the wellbore wall to obtain full hoop stress restoration. To conduct a successful wellbore strengthening operation Fracture width at the wellbore phase has to be determined and this Fracture area has to be targeted with the lost circulation material with a suitable particle size distribution.
