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This paper will present the integrated extraordinary solutions founded during Extended-Reach Drilling (ERD) campaign on Lebedinskoye oilfield, which is located on the Northern East shelf of Sakhalin Island. As a green field, Lebedinskoye had a high level of geological uncertainty. Specifics of location made the well profiles complex - with a high Directional Difficulty Index – DDI (SPE ref. 59196) up to 7.2 and ERD ratio up to 2.94. Island logistics imposed critical constraints to the project planning. Rosneft and Schlumberger established the goal to optimize the well construction time to bring additional savings in the period of industry downturn. At the same time, a project team set ambitious goals to plan and execute operations to a safe and high quality standard. An integrated approach was deemed essential for success of such complex project. Integration provided a seamless interface bridging multi-discipline solutions and technologies to ensure high quality planning together with risk management. Several technologies in the project were implemented for first time in Russia. A "point the bit" rotary-steerable system enabled drilling the 17 ½" section in the one run of 2168m. A non-cemented liner eliminated the additional cost and time for a cement job as well as the potential impairment of the pay zone. The project team successfully run floated 9 5/8" casing to the final depth and eliminated major risks of the campaign. The Lebedinskoye was the first time the client implemented advanced LWD tools for deep reservoir mapping. In the result, 97% of 1962m horizontal section placed in the target zone, which became a new record for the Client. Finally, integrated approach, new technologies and solutions reduced well construction time by 25% as compared to similar offset extended-reach wells and made the project economical efficient in the period of downturn.

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 the article is to analyze the impact of concept mapping on the level and quality of assimilation of learning material in higher mathematics in the process of independent study. Methodology. Based on a review of the main provisions of modern theory of learning and generalization of research results presented in scientific papers on the scope of application of concept maps in the learning process, such a training experiment was conducted. For students of the two experimental groups on a certain topic of the discipline “Higher Mathematics” were offered to build conceptual maps in addition to the common teaching methods. It considered as an independent creative task. In the other two groups, which were under control, students had to study the same topic of the discipline, using traditional methods. Results. It was determined that the results of the colloquium composed of students of experimental groups were significantly higher than those of students of control groups who did not use mapping as a method of learning during independent work. The average score obtained by students of experimental groups for the colloquium was almost 80 points, while for students of control groups it was only 72 points. Using Student’s test, the significance of the difference between the values of the sample averages of these indicators proved. If we compare the average scores for different types of tasks, the most significant was the difference in the performance of heuristic tasks, which reflect the ability to apply the acquired knowledge to solve practical problems of economic content. Conclusions. The positive influence of the use of concept mapping in independent work of students established, which proves the thesis about the feasibility of using concept mapping as a learning tool. Further introduction of concept maps in the educational process should be based on the development of complex theoretical and practical, as well as competency-oriented tasks.

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