Managing the Risk of Wellbore Instability Using Geomechanical Modeling and Wellbore Stability Analysis for Muzhil Shale Formation in Gulf of Suez, Egypt

Wellbore instability constitutes potential risks during wellbore drilling operation; these risks may cause complicated states, and in some cases, can lead to costly operational issues. In this study we present the best solution by predicting and quantifying wellbore instability in Muzhil field, Gulf of Suez, using a 1-DMechanical Earth Model (1DMEM) built with well logs, pressure measurements, and drilling events reports. Firstly we created 1DMEM by calculating the pore pressure, vertical stress, rock strength, rock elastic parameters, and horizontal stresses. Mohr Coulomb, Modified Lade and Mogi Coulomb failure criteria determined the well deformation possibility. Lastly 1-DMEM can be used to conduct a comprehensive geo-mechanical wellbore stability analysis for the trouble zones of Muzhil Formation. 1-DMEM results showed that the best azimuth for Vertical and slightly inclined Wells will be (40º–60º) clockwise from the North, i.e. parallel to SHmin (NE40SW). The wellbore stability analysis showed that the vertical and low deviated wellbore (less than 40º) is safe and more stable than the horizontal and high deviated wellbore and unsuitable Mud Weight (MW) is a major cause of the wellbore instability. The optimal solution to wellbore instability is to follow the optimum wellbore path and use safe MW. The optimum MW in shale formation ranges from (13.5-15) ppg. The results contribute in development plan of the wellbores nearby the studied area and reducing nonproductive time and cost

Diagnostic Accuracy of the Leishmania OligoC-TesT and NASBA-Oligochromatography for Diagnosis of Leishmaniasis in Sudan

The leishmaniases are a group of vector-borne diseases caused by protozoan parasites of the genus Leishmania. The parasites are transmitted by phlebotomine sand flies and can cause, depending on the infecting species, three clinical manifestations of leishmaniasis: visceral leishmaniasis (VL), post kala-azar dermal leishmaniasis (PKDL) and cutaneous leishmaniasis (CL) including the mucocutaneous form. VL, PKDL as well as CL are endemic in several parts of Sudan, and VL especially represents a major health problem in this country. Molecular tests such as the polymerase chain reaction (PCR) or nucleic acid sequence based assay (NASBA) are powerful techniques for accurate detection of the parasite in clinical specimens, but broad use is hampered by their complexity and lack of standardisation. Recently, the Leishmania OligoC-TesT and NASBA-Oligochromatography were developed as simplified and standardised PCR and NASBA formats. In this study, both tests were phase II evaluated for diagnosis of VL, PKDL and CL in Sudan

Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial: An intention-to-treat analysis of amputation-free and overall survival in patients randomized to a bypass surgery-first or a balloon angioplasty-first revascularization strategy

BackgroundA 2005 interim analysis of the Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial showed that in patients with severe lower limb ischemia (SLI; rest pain, ulceration, gangrene) due to infrainguinal disease, bypass surgery (BSX)-first and balloon angioplasty (BAP)-first revascularization strategies led to similar short-term clinical outcomes, although BSX was about one-third more expensive and morbidity was higher. We have monitored patients for a further 2.5 years and now report a final intention-to-treat (ITT) analysis of amputation-free survival (AFS) and overall survival (OS).MethodsOf 452 enrolled patients in 27 United Kingdom hospitals, 228 were randomized to a BSX-first and 224 to a BAP-first revascularization strategy. All patients were monitored for 3 years and more than half for >5 years.ResultsAt the end of follow-up, 250 patients were dead (56%), 168 (38%) were alive without amputation, and 30 (7%) were alive with amputation. Four were lost to follow-up. AFS and OS did not differ between randomized treatments during the follow-up. For those patients surviving 2 years from randomization, however, BSX-first revascularization was associated with a reduced hazard ratio (HR) for subsequent AFS of 0.85 (95% confidence interval [CI], 0.5-1.07; P = .108) and for subsequent OS of 0.61 (95% CI, 0.50-0.75; P = .009) in an adjusted, time-dependent Cox proportional hazards model. For those patients who survived for 2 years after randomization, initial randomization to a BSX-first revascularization strategy was associated with an increase in subsequent restricted mean overall survival of 7.3 months (95% CI, 1.2-13.4 months, P = .02) and an increase in restricted mean AFS of 5.9 months (95% CI, 0.2-12.0 months, P = .06) during the subsequent mean follow-up of 3.1 years (range, 1-5.7 years).ConclusionsOverall, there was no significant difference in AFS or OS between the two strategies. However, for those patients who survived for at least 2 years after randomization, a BSX-first revascularization strategy was associated with a significant increase in subsequent OS and a trend towards improved AFS

Combining active and passive seismic methods for the characterization of urban sites in Cairo, Egypt

The geology at Kottamiya, Rehab City and Zahraa–Madinat–Nasr to the East of Cairo (Egypt) is composed of low-velocity sediments on top of a rigid rock basement. Such sediments include the loose sands of the Gebel Ahmar formation, marl and shales of Maadi formation, in addition to sparse quaternary soil covers. Due to the contrast of the seismic impedance with the underlying bedrock, these soft sediments have the potential of considerably amplifying the ground motion during an earthquake. For the evaluation of site-specific seismic hazard, we computed the seismic site response in these areas by developing 1-D velocity models and derived average seismic velocities, including Vs30. To do that, we applied different active and passive source techniques, including the horizontal to vertical Fourier spectral ratio of ambient vibration recordings and multichannel analysis of artificially generated surface waves. A set of models representing the velocity structure of the site is then obtained by combined inversion of Rayleigh wave dispersion curves and ellipticity functions. While dispersion curves are used to constrain the uppermost low-velocity part of the soil profile, ellipticity helps in resolving the structure at the depth of the sediment–bedrock interface. From the retrieved velocity models, numerical ground-motion amplification is finally derived using 1-D SH-wave transfer function. We account for uncertainty in amplification by using a statistical model that accounts for the misfit of all the inverted velocity profiles. The study reveals that the different sites experience an important frequency-dependent amplification, with largest amplification occurring at the resonance frequencies of the sites. Amplification up to a factor of 5 is found, with some variability depending on the soil type (Vs30 ranges between 340 and 415 m s−2). Moreover, amplification is expected in the frequency range that is important for buildings (0.8–10 Hz), which is additional confirmation for the need of microzonation analysis of the area. The obtained results will be used for the development of a new seismic hazard model.ISSN:0956-540XISSN:1365-246

Joint geophysical and geochemical evaluation of source rocks – A case study in Sayun-Masila basin, Yemen

Integration of geophysical and geochemical approaches is used for qualitative and quantitative evaluation of source rocks. The Upper Jurassic rocks in the Sayun-Masila basin are used as a case study due to its high hydrocarbon potentiality. Stratigraphically, these rocks could be differentiated from base to top into: Shuqra, Madbi and Nayfa formations. The total organic carbon (TOC) values were determined in the shale and/or carbonate intervals of these formations from four studied wells by the ΔlogR method using sonic, resistivity and gamma-ray log data. Then the discriminant analysis was applied in differentiating source from non-source rocks. Also, the effect of the burial and thermal histories on the organic material maturation and the oil and/or gas generation was studied through the application of two analytical methods, namely, the level of organic metamorphism (LOM) and the time-temperature index (TTI), depending on the corrected temperature logs integrated with the time and depth data. The reliability of the obtained results has been confirmed and combined with the results supplied from geochemical analyses. The Upper Jurassic sediments are found to be oil–prone source rock in a mature stage. The Madbi Formation is considered as the most effective source rock. The burial and thermal histories of the basin in four modeled wells showed that mature oil generation window and hydrocarbon expulsion would have been initiated in the depocenters from Upper Jurassic Madbi Formation source rock during Late Cretaceous to Middle Miocene time. Keywords: Source rocks evaluation, ΔLogR method, Total organic carbon (TOC), Time-temperature index (TTI), Sayun-Masila basin, Yeme

Probabilistic seismic hazard model for Cairo, Egypt: estimates and uncertainties

A new seismic hazard model for Cairo, the capital city of Egypt is developed herein based on comprehensive consideration of uncertainties in various components of the probabilistic seismic hazard analysis. The proposed seismic hazard model is developed from an updated catalogue of historical and instrumental seismicity, geodetic strain rates derived from GPS-based velocity-field of the crust, and the geologic slip rates of active faults. The seismic source model consists of area sources and active faults characterised to forecast the seismic productivity in the region. Ground motion prediction models are selected to describe the expected ground motion at the sites of interest. The model accounts for inherent epistemic uncertainties of statistical earthquake recurrence; maximum magnitude; ground motion prediction models, and their propagation toward the obtained results. The proposed model is applied to a site-specific hazard analysis for Kottamiya, Rehab City and Zahraa-Madinat-Nasr (hereinafter referred to as Zahraa) to the East of Cairo (Egypt). The site-specific analysis accounts for the site response, through the parameterization of the sites in terms of average 30-m shear-wave velocity (Vs30). The present seismic hazard model can be considered as a reference model for earthquake risk mitigation and proper resilience planning.ISSN:1570-761XISSN:1573-145

Deep learning for environmentally robust speech recognition

Deep learning is an emerging technology that is one of the most promising areas of artificial intelligence. Great strides have been made in recent years which resulted in increased efficiency with regards to many applications, including speech. Despite this, an environmentally Robust Speech Recognition system is still far from being achieved. In this article, an investigation of previous work has been conducted. The use of deep learning in speech recognition was analyzed and a proper deep learning architecture was identified. A method using convolutional neural network (CNN) is used with the aim of enhancing the performance of speech recognition systems (SRS). This study found that this CNN-based approach achieves a 94.32% validated accuracy