ExtPFA: Extended Persistent Fault Analysis for Deeper Rounds of Bit Permutation Based Ciphers with a Case Study on GIFT

2020 ◽  
pp. 101-122
Author(s):  
Priyanka Joshi ◽  
Bodhisatwa Mazumdar
Keyword(s):  
Fault Analysis

How Chosen Seismic Fault Picking Strategy Influences Subsequent Fault Analyses: A Case Study from the Horda Platform, with Implications for CO2 storage

2021 ◽  
Author(s):  
Emma Michie ◽  
Mark Mulrooney ◽  
Alvar Braathen
Keyword(s):  
Fluid Flow ◽  
Co2 Storage ◽  
Fault Analysis ◽  
Surface Generation ◽  
Storage Site ◽  
Seismic Line ◽  
Fault Stability ◽  
Line Spacing ◽  
Fault Growth

<p>Significant uncertainties occur through varying methodologies when interpreting faults using seismic data.  These uncertainties are carried through to the interpretation of how faults may act as baffles/barriers or increase fluid flow.  Seismic line spacing chosen by the interpreter when picking fault segments, as well as the chosen surface generation algorithm used, will dictate how detailed or smoothed the surface is, and hence will impact any further interpretation such as fault seal, fault stability and fault growth analyses.</p><p>This contribution is a case study showing how picking strategies influence analysis of a bounding fault in terms of CO<sub>2</sub> storage assessment.  This example utilizes data from the Smeaheia potential storage site within the Horda Platform, 20 km East of Troll East.  This is a fault bound prospect, known as the Alpha prospect, and hence the bounding fault is required to have a high seal potential and low chance of reactivation upon CO<sub>2</sub> injection.</p><p>We can observe that an optimum spacing for fault interpretation for this case study is set at approximately 100 m.  It appears that any additional detail through interpretation with a line spacing of ≤50 m simply adds further complexities, associated with sensitivities by the individual interpreter.  Hence, interpreting at a finer scale may not necessarily improve the subsurface model and any related analysis, but in fact lead to the production of highly irregular surfaces, which impacts any further fault analysis.  Interpreting on spacing greater than 100 m often leads to overly smoothed fault surfaces that miss details that could be crucial, both for fault seal / stability as well as for fault growth models.</p><p>Uncertainty associated with the chosen seismic interpretation methodology will follow through to subsequent fault seal analysis, such as analysis of whether in situ stresses, combined with increased pore pressure through CO<sub>2</sub> injection, will act to reactivate the faults, leading to up-fault fluid flow / seep.  We have shown that changing picking strategies significantly alters the interpreted stability of the fault, where picking with an increased line spacing has shown to increase the overall fault stability, and picking using every line leads to the interpretation of a critically stressed fault.  Alternatively, it is important to note that differences in picking strategy show little influence on the overall predicted fault membrane seal (i.e. shale gouge ratio) of the fault, used when interpreting the fault seal capacity for a fault bound CO<sub>2</sub> storage site.</p>

scholarly journals Fault Interpretation Uncertainties using Seismic Data, and the Effects on Fault Seal Analysis: A Case Study from the Horda Platform, with Implications for CO<sub>2</sub> storage

2021 ◽  
Author(s):  
Emma A. H. Michie ◽  
Mark J. Mulrooney ◽  
Alvar Braathen
Keyword(s):  
Fluid Flow ◽  
Seismic Data ◽  
Growth Models ◽  
Fault Analysis ◽  
Surface Generation ◽  
Co2 Injection ◽  
Line Spacing ◽  
Fault Growth ◽  
Fault Interpretation

Abstract. Significant uncertainties occur through varying methodologies when interpreting faults using seismic data. These uncertainties are carried through to the interpretation of how faults may act as baffles/barriers or increase fluid flow. How fault segments are picked when interpreting structures, i.e. what seismic line spacing is specified, as well as what surface generation algorithm is used, will dictate how detailed the surface is, and hence will impact any further interpretation such as fault seal or fault growth models. We can observe that an optimum spacing for fault interpretation for this case study is set at approximately 100 m. It appears that any additional detail through interpretation with a line spacing of ≤ 50 m adds complexity associated with sensitivities by the individual interpreter. Further, the location of all fault segmentation identified on Throw-Distance plots using the finest line spacing are also observed when 100 m line spacing is used. Hence, interpreting at a finer scale may not necessarily improve the subsurface model and any related analysis, but in fact lead to the production of very rough surfaces, which impacts any further fault analysis. Interpreting on spacing greater than 100 m often leads to overly smoothed fault surfaces that miss details that could be crucial, both for fault seal as well as for fault growth models. Uncertainty in seismic interpretation methodology will follow through to fault seal analysis, specifically for analysis of whether in situ stresses combined with increased pressure through CO2 injection will act to reactivate the faults, leading to up-fault fluid flow/seep. We have shown that changing picking strategies alter the interpreted stability of the fault, where picking with an increased line spacing has shown to increase the overall fault stability. Picking strategy has shown to have minor, although potentially crucial, impact on the predicted Shale Gouge Ratio.

scholarly journals Fault interpretation uncertainties using seismic data, and the effects on fault seal analysis: a case study from the Horda Platform, with implications for CO<sub>2</sub> storage

Solid Earth ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 1259-1286
Author(s):  
Emma A. H. Michie ◽  
Mark J. Mulrooney ◽  
Alvar Braathen
Keyword(s):  
Fluid Flow ◽  
Seismic Data ◽  
Growth Models ◽  
Fault Analysis ◽  
Surface Generation ◽  
Co2 Injection ◽  
Line Spacing ◽  
Fault Growth ◽  
Fault Interpretation

Abstract. Significant uncertainties occur through varying methodologies when interpreting faults using seismic data. These uncertainties are carried through to the interpretation of how faults may act as baffles or barriers, or increase fluid flow. How fault segments are picked when interpreting structures, i.e. which seismic line orientation, bin spacing and line spacing are specified, as well as what surface generation algorithm is used, will dictate how rugose the surface is and hence will impact any further interpretation such as fault seal or fault growth models. We can observe that an optimum spacing for fault interpretation for this case study is set at approximately 100 m, both for accuracy of analysis but also for considering time invested. It appears that any additional detail through interpretation with a line spacing of ≤ 50 m adds complexity associated with sensitivities by the individual interpreter. Further, the locations of all seismic-scale fault segmentation identified on throw–distance plots using the finest line spacing are also observed when 100 m line spacing is used. Hence, interpreting at a finer scale may not necessarily improve the subsurface model and any related analysis but in fact lead to the production of very rough surfaces, which impacts any further fault analysis. Interpreting on spacing greater than 100 m often leads to overly smoothed fault surfaces that miss details that could be crucial, both for fault seal as well as for fault growth models. Uncertainty in seismic interpretation methodology will follow through to fault seal analysis, specifically for analysis of whether in situ stresses combined with increased pressure through CO2 injection will act to reactivate the faults, leading to up-fault fluid flow. We have shown that changing picking strategies alter the interpreted stability of the fault, where picking with an increased line spacing has shown to increase the overall fault stability. Picking strategy has shown to have a minor, although potentially crucial, impact on the predicted shale gouge ratio.

Case study on fault analysis using PMU

2014 ◽  
Author(s):  
Prithwish Mukhopadhyay ◽  
Rajkumar Anumasula ◽  
Abhimanyu Gartia ◽  
Chandan Kumar ◽  
Pushpa Seshadri ◽  
...  
Keyword(s):  
Fault Analysis

scholarly journals Persistent Fault Analysis on Block Ciphers

2018 ◽  
pp. 150-172 ◽  
Author(s):  
Fan Zhang ◽  
Xiaoxuan Lou ◽  
Xinjie Zhao ◽  
Shivam Bhasin ◽  
Wei He ◽  
...  
Keyword(s):  
Time Synchronization ◽  
Fault Injection ◽  
Block Ciphers ◽  
Fault Analysis ◽  
Experimental Results ◽  
Fault Attacks ◽  
Intrinsic Nature ◽  
Fault Attack ◽  
Modular Redundancy

Persistence is an intrinsic nature for many errors yet has not been caught enough attractions for years. In this paper, the feature of persistence is applied to fault attacks, and the persistent fault attack is proposed. Different from traditional fault attacks, adversaries can prepare the fault injection stage before the encryption stage, which relaxes the constraint of the tight-coupled time synchronization. The persistent fault analysis (PFA) is elaborated on different implementations of AES-128, specially fault hardened implementations based on Dual Modular Redundancy (DMR). Our experimental results show that PFA is quite simple and efficient in breaking these typical implementations. To show the feasibility and practicability of our attack, a case study is illustrated on the shared library Libgcrypt with rowhammer technique. Approximately 8200 ciphertexts are enough to extract the master key of AES-128 when PFA is applied to Libgcrypt1.6.3 with redundant encryption based DMR. This work puts forward a new direction of fault attacks and can be extended to attack other implementations under more interesting scenarios.

Fault Analysis and Optimal Balancing of Bowing of Steam Turbine Rotor Under Long-Term Service

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Jingming Chen ◽  
Dongxiang Jiang ◽  
Chao Liu
Keyword(s):  
Steam Turbine ◽  
Traditional Approach ◽  
Turbine Rotor ◽  
Fault Analysis ◽  
Time Service ◽  
Steam Turbine Rotor ◽  
Start Up ◽  
Long Time

In recent years, bowing of steam turbine rotor under long time service occurs in several high-parameter units. Collected data show that the bending of the haywire rotor is increasing continuously, which results in excessive vibration in operation and even causes over-limit vibration during start-up. In order to suppress the vibration, balancing is utilized in field with the traditional approach that the balancing mass is placed in the section of the rotor close to the bearing. However, the balancing with the traditional approach could only reduce the vibration temporarily. In the long time scale, the bowing is still propagating or even gets worse after the balancing. To determine the cause of bowing and form optimal balancing approach, analysis is carried out in this work including: (i) fault cause and its treatment of bowing of steam turbine rotor under long time service is studied with elastic–plastic mechanics and creep mechanism taken in account; (ii) a case study was carried out, where the bowing process was simulated and validated with the field monitoring data; (iii) the phenomenon of the traditional balancing method was illustrated with rotordynamics analysis, where the influence of whirling is included. Based on the analysis, the cause of bowing is determined as uneven creep effect. And the balancing method would influence the whirling mode, which would worsen bowing in the traditional balancing method. Based on this conclusion, an optimized balancing method was developed to reduce the vibration and prevent bowing propagation simultaneously.

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