Casing While Drilling Successfully Implemented for the First Time in High Risk Area of the Bahrain Field

One known risk of the Awali field is hole collapsing in the surface section due to the presence of floating bloulders and cavities in areas of the field; resulting in wells being abandoned as conventional drilling was not enough to solve this issue. In 2019, Schlumberger and Tatweer Petroleum combined forces to improve production of Ostracod/Magwa shallow reservoirs by drilling wells in new areas of the field which included drilling in locations with offset wells that were abandoned due to hole collapse issues in the first 500’ interval. Drilling campaign started in june 2019 and drilled succesfully two wells, but two others were abandonned due to hole collapse issues. These abandonned wells were in very promising production areas as per the reservoir model and due to the shallowenest of the reservoir, it was not possible to move the surface location. Therefore, the issues in the surface section needed to be solved in order to maximize profits in the country. Following a rigerous study for determining which is the optimal solution for drilling the surface section in this area of the field, Casing While Drilling (CwD) technology was selected and implemented in August 2019 in well A-1530D, next to the previous abandoned wells. CwD operation was performed with excellent results by drilling from 101ft to 520ft with no issues. CwD successfully isolated the higly problematic zones in the surface section and more importantly, allowed to reach areas of the reservoir that had high potential for production.

Treatment tactics and outcomes of complications of intrastromal MyoRing implantation and corneal crosslinking in keratoconus

Purpose. To analyze the nature and frequency of intra - and postoperative complications during MyoRing implantation and corneal crosslinking in patients with keratoconus and to develop methods for their treatment and prevention. Material and methods. We conducted a study of the results of MyoRing implantation in 131 patients (147 eyes) with keratoconus II-III. Corneal rings with a diameter of 5-6 mm and a thickness of 280-320 µm were implanted. PocketMaker microkeratome (Dioptex GmbH, Austria) was used to create a stromal pocket during the implantation of the ICR. The patients were divided into the control group (32 patients, 34 eyes) – using the standard ICR implantation technology and the main group (38 patients, 42 eyes) – ICR implantation using the developed tools. Results. Among the complications, intraoperatively, the eruption of the stromal pocket was noted due to the loss of vacuum during the application of the applicator in 4 cases. In the long term, after 10 and 12 months, patients underwent ICR reimplantation with a positive result. In 2 cases, the surface location of the implant led to ring extrusion, which may have been due to the thinning of the surface layers, and subsequently keratoplasty was performed on the patients. In 1 case, the patient's pronounced deposition of lamellar deposits caused dissatisfaction of a cosmetic nature. At the request of the patients, the rings were removed, and in the following terms, the patient made up for the visual defect by wearing hard contact lenses. Conclusion. A moderate number of complications indicates the relative safety of the method of intrastromal keratoplasty. The use of the proposed instruments during the operation provides a significant reduction in the frequency of complications compared to the results with the standard technique of forming a corneal tunnel. Thus, it was found that the optimized method of implantation of MyoRing intrastromal rings reduces corneal trauma, simplifies the manipulation of the ring and reduces the total operation time by 1.4 times. Key words: keratoconus, intrastromal corneal rings, MyoRing, corneal crosslinking, complications.

Evaluation of failure of slopes with shaking-induced cracks in response to rainfall

Centrifuge model tests on slopes subject to shaking and rainfall have been performed to examine the response of slopes with shaking-induced cracks to subsequent rainfall and evaluate the corresponding landslide-triggering mechanisms. The failure pattern of the slope subject to shaking and then rainfall was found different from that of the slope subject to only rainfall. When shaking caused cracks on the slope shoulder and rupture line below, the mobilized soil slid along the slip surface that extended to the rupture line, the main crack became the crown of the undisturbed ground once the slope was subject to a subsequent rain event, and the progression of the landslide was related to the rainfall intensity. During the landslide caused by light rainfall, the main scarp kept exposing itself in the vertically downward direction while the ground behind the main crack in the crack-containing slope remained undisturbed. The detrimental effect of cracks on soil displacement was more evident when the slope was exposed to heavy post-shaking rainfall, resulting in a rapid and massive landslide. Additionally, the volume of displaced material of the landslide, the main scarp area on the upper edge, and the zone of accumulation were larger in the crack-containing slope subject to heavy rainfall, in comparison with those in the crack-free slope. The deformation pattern of slopes with shaking-induced cracks during rainfall was closely related to rainfall intensity and the factor of safety provided a preliminary estimation of slope stability during rainfall. Moreover, even when subjected to the same rainfall, the slopes with antecedent shaking-induced cracks displayed different levels of deformation. The slope that experienced larger shaking had greater deformation under the following rainfall, and the shaking-induced slope deformation also controlled the slip surface location. Finally, the velocity of rainfall-induced landslide could be greatly influenced by the prior shaking event alone. Despite being under light rainfall, the slope that has encountered intense previous shaking exhibited an instant landslide.

Monoclonal Antibodies to S and N SARS-CoV-2 Proteins as Probes to Assess Structural and Antigenic Properties of Coronaviruses

Antibodies targeting the spike (S) and nucleocapsid (N) proteins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are essential tools. In addition to important roles in the treatment and diagnosis of infection, the availability of high-quality specific antibodies for the S and N proteins is essential to facilitate basic research of virus replication and in the characterization of mutations responsible for variants of concern. We have developed panels of mouse and rabbit monoclonal antibodies (mAbs) to the SARS-CoV-2 spike receptor-binding domain (S-RBD) and N protein for functional and antigenic analyses. The mAbs to the S-RBD were tested for neutralization of native SARS-CoV-2, with several exhibiting neutralizing activity. The panels of mAbs to the N protein were assessed for cross-reactivity with the SARS-CoV and Middle East respiratory syndrome (MERS)-CoV N proteins and could be subdivided into sets that showed unique specificity for SARS-CoV-2 N protein, cross-reactivity between SARS-CoV-2 and SARS-CoV N proteins only, or cross-reactivity to all three coronavirus N proteins tested. Partial mapping of N-reactive mAbs were conducted using truncated fragments of the SARS-CoV-2 N protein and revealed near complete coverage of the N protein. Collectively, these sets of mouse and rabbit monoclonal antibodies can be used to examine structure/function studies for N proteins and to define the surface location of virus neutralizing epitopes on the RBD of the S protein.

Choice of Interceptor Aerodynamic Lifting Surface Location based on Autopilot Design Considerations

Interceptors operate at wide range of operating conditions in terms of Mach number, altitude and angle of attack. The aerodynamic design caters for such wide operating envelope by appropriate sizing of lifting and control surfaces for meeting the normal acceleration capability requirements. The wide range of operating conditions leads to an inevitable spread in center of pressure location and hence spread in static stability. The performance of control design is a strong function of the aerodynamic static stability. The total operating envelope can be bifurcated into statically stable and unstable zones and the aerodynamic lifting surface location can be used as a control parameter to identify the neutral stability point. During the homing phase lesser static stability is desirable for good speed of response, hence the lifting surface location needs to be chosen based on the capability of control to handle instability. This paper analyses the limitations of autopilot design for the control of an unstable interceptor and brings out a method to identify the optimum aerodynamic lifting surface location for efficiently managing static margin while satisfying the control limitations and homing phase performance. This provides an input on the most appropriate lifting surface location to the aerodynamic designer during the initial CFD based aerodynamic characterisation stage itself, before commencing the rigorous wind tunnel based characterisation.

NORMALIZATION OF THE PERMISSIBLE ERROR AND THE CHOICE OF MEASUREMENT TOOLS FOR CONTROLLING DEVIATIONS IN THE SHAPE AND LOCATION OF SURFACES

The reliability of repaired engines is determined by many factors, among which the accuracy of the geometric parameters of engine parts plays an important role. Errors in the shape and location of the surfaces of parts cause additional acceleration of moving parts and reduce the accuracy of kinematic pairs. Violation of the movement kinematics of parts leads to a deterioration in the technical performance of the engine. In this regard, increasing the level of metrological control of shape deviation and surface location is one of the ways to improve the quality of engine repairs. Analysis of the measurement tools recommended in the reference literature has shown that they were chosen irrespective of the controlled values and without taking into account the type of measurement. The purpose of this study is to develop recommendations for improving metrological control of deviations in the shape and location of surfaces of parts during engine repairs. The paper provides theoretical grounds for choosing the criteria for selecting measuring instruments to control deviations in the shape and location of the surfaces of parts, taking into account the relevant formula. The result of indirect measurement and the measurement error (deviation of the shape and location of the surfaces of parts) are considered random values functionally related to the measured values (diameters of a part). The limits of permissible measurement errors and measurement tool errors are determined to control the deviation of the shape and location of the surfaces of new engine parts and parts subject to troubleshooting. The authors have carried out a comparative analysis of the obtained values with the error values of measuring instruments recommended in the reference literature. It has been established that most of the recommended measuring instruments have an error greater than the allowed measurement error. To reduce the risk of accepting parts that exceed the deviation norms relating to the shape and location of surfaces, it has been suggested using special criteria when selecting measuring instruments.