Equiatomic CoCrFeMnNi, one of the well-known high-entropy alloys, possesses attractive mechanical properties for many potential applications. In this research, the effects of heat treatment on additively manufactured CoCrFeMnNi materials were studied. A pilot experiment was conducted to select two selective laser melting (SLM) conditions of different laser scanning speeds based on the density and porosity of obtained materials. Thereafter, microstructure, tensile properties, impact fracture, microhardness, and corrosion resistance were investigated for the materials obtained under the two selected SLM conditions, with and without heat treatment. It was discovered that while the texture with a strong <100> alignment was observed in both as-built and heat treated materials, the texture of heat treated materials was stronger. Also, heat treatment drastically improved the ductility of as-built CoCrFeMnNi by 23 – 59% for the selected SLM conditions, while the ultimate tensile strength showed only negligible change. The increase of ductility was believed to result from the release of residual strain and the increase of average grain size after heat treatment. Moreover, heat treatment was able to bring noticeable improvement in energy absorption for the as-built CoCrFeMnNi, reflected by 11 – 16% more energy absorption. Besides, all studied materials showed signs of ductile fracture, but more signs of brittle fracture, such as cleavage facets, were found in the as-built materials as compared with the heat-treated materials. In addition, higher laser scan speed was found to cause moderate reduction in corrosion resistance. Effect of heat treatment was also negative and mild for lower scanning speed case. However, the highest reduction in corrosion resistance was observed after heat treatment of the high laser scanning speed case.

Exploration drilling in the Samgori-Patardzeuli area started in 1974 for the Lower Eocene – Paleocene formations, during the exploration campaign oil discoveries were made in Middle Eocene sediments. The Samgori-Patardzeuli Middle Eocene delivered the bulk of the production in Georgia and is now a depeleted reservoir. Although more than 200 well have been drilled up to date, only 13 wells from them were drilled to the Lower Eocene, therefore Lower Eocene have not been studied sufficiently and gas reserves have not been estimated. Despite this, 29.97 million m3 of gas has been prodused so far from the Lower Eocene sediments. This paper describes the successful experience of drilling one of the deepest exploration well PAT-E1 on the Patardzeuli field to evaluate Lower Eocene gas reservoirs. Exploration drilling for oil and gas involves numerous risks related with limited information about geological structure and drilling conditions. Successful drilling of planned deep exploration well requires good understanding of hole stability to find the optimal mud properties, proper casing seat selection and out-of-the-box engineering solutions to reach well objectives. Multidisciplinary team, including drilling engineers, reservoir engineer, geologist, geomechanicist, petrophysicist, drilling engineer, mud engineer worked in collaboration to design and drill one of the deepest exploration well in the area. Interval from surface till Upper Eocene was characterized by offset wells, but most of decisions were made based on trial and error. Main problems in the upper sections were related with extreme borehole breakouts and severe losses, while the lower sections was known for losses and gas kick. The PAT-E1 well was successfully drilled to the main target in the Lower Eocene and penetrated down to the top of Upper Cretaceous formation with well TD at 5020 m. Elimination one of intermediate sections allows to decrease well construction time and costs with controlled risks of borehole breakouts and losses. Geological support allowed to place casing shoes in a very narrow safe interval to separate the interval of high breakout risk and total loss interval of fractured reservoir with abnormally low pore pressure. Real time pore pressure and fracture pressure prediction service in the lower sections allowed to monitor hole condition in real time and provided timely recommendations for well control. The PAT-E1 well is first deep exploration well that was sucsesfully drilled Upper Cretaceous formation on Patardzeuli field which allow to complete advanced formation evaluation and testing. Best practices developed while drilling this well will be applied for future safe drilling in the region.

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This paper provides insights of planning, execution and the results of the application of selective flotation or "mud over air" technique while running 9 5/8-in production liner into an extreme-extended-reach well in Sakhalin, the longest well ever drilled by RN-Sakhalinmorneftegaz to date. Extreme Reach Drilling (ERD) well has a shallow true vertical depth and a long horizontal departure imposing significant challenges of conveying 9 5/8-in liner to the required depth. When both conventional and full flotation methods cannot guarantee delivering casing to planned depth due to high torque and drag, lack of weight and string buckling, a new operational approach of selective flotation was considered. Mud over air, specifically "air cavity" technique implies running a bottom portion of the casing filled with mud, then an empty portion to reduce drag and a top portion filled with drilling fluid for additional weight to provide some additional push to overcome residual drag. This article outlines unique practices of selective flotation technique covering the job specific features, its main risks and corresponding mitigation measures. The selective flotation or "mud over air" concept together with detailed risk assessment and engineering of a single hydro-mechanical liner hanger and flotation collar system enabled successful conveyance of 9 5/8-in liner to its setting depth during drilling the longest extended reach well in the project.

The purpose of this study is to improve spacecraft shielding from radiation in space. It focuses on the evaluation of shielding efficiency of different materials. The efficiency of a shield is evaluated by the dose profile within the shield and the amount of dose absorbed by a target using the Monte Carlo transport code called FLUKA. The output of this code is validated by recreating the experiments from published papers and comparing the results. Once the FLUKA's output is validated, the efficiency of sixteen materials, subject to SPE and GCR sources, are evaluated. The efficiency comparison is made by fixing the area density of a shield.It was found that polyethylene, water, carbon and silicon outperform aluminum -the primary metal used in spacecraft. In case of composite shield, made of layers of different materials, the 3Carb-9Al combination has better performance than the shield made just of aluminum. This holds true for both Solar Particle Events (SPEs) and Galactic Cosmic Ray (GCR). However, the choice of material is more efficient at shielding from SPE particles rather than from GCR. In case of GCR, the choice of materials is found to have rather small effect on the efficiency of a shield. The percent difference between the rate of dose absorption by a target, shielded by different materials, is within about 9%. Secondary particles make a significant contribution to the target's dose. For SPEs, the secondary particles are primarily electrons and neutrons. For GCRs, the secondary particles are primarily pions, α-particles and electrons. Protons contribute more than 50% to the target's dose in both cases. v ACKNOWLEDGMENTS