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Abstract. Insulation breaks are used in cryogenic lines with a gas or liquid at temperatures of 4.2-300 K and pressure up to 30 MPa to isolate the parts of electrophysical setup with different electrical potential. Novel cryogenic high voltage (HV) insulation breaks for the electrophysical equipment that uses the effect of superconductivity was developed in the D.V. Efremov Institute of Electrophysical Apparatus (NIIEFA). These insulation breaks consist of glass-reinforced plastic cylinder equipped with channel for cryoagent and stainless steel end fittings. The main design feature of new kind HV break is spiral channel instead of linear one. This approach allowed to increase the breakdown voltage and to decrease the overall dimensions of insulation breaks. The design length of the spiral channel depends on HV requirements and the kind of cryoagent. To provide the wide range of operating voltages, temperatures and pressures the insulation breaks with various dimensions were developed. To provide an acceptance test of breaks as manufactured the special test facility was prepared. Helium tightness test with a level 1.2·10 -11 m 3 ·Pa/s under up to 30 MPa, HV test up to 135 kV and different kinds of mechanical tests could be provided at room and liquid nitrogen temperatures.

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Summary This paper is a description of the approach to the construction of technologically complex and unique well with horizontal completion of 15 branches, the first in Russia and Eastern Siberia. The experience of multilateral technology (MLT) wells application along with detailed well planning and training of the involved personnel made it possible to cope with all challenges and to achieve record technological indicators. Project issues: High abrasive formations of the reservoir; VSS due to borehole enlargements and interbedding/stringers occurrence. High alternating bending moments during fishbone wells construction. Abnormal low formation pressure. Difficulties in fracture gradient prediction. Lack of reservoir pressure compensation in gas-oil-water zone (GOWZ) is a cause of mud loses. Extensive loads to the drill string. The main of the trial project was to confirm the possibility of 15-branches MLT well drilling in the geological conditions of the region.

A case study of Srednebotuobinskoye Field, the oil deposits of which are confined to gas-oil-water and oil-water zones, describes the evolution of design decisions for development after the first year of asset operation. The first production data showed the need for separate solutions for under-gas-cap and water-oil zones, and the formation of a new field development concept, and their justification was the purpose of the work the results of which are shown in this paper. The difference with the previously performed work lies in the fact that development decisions were made based on the results of multiple runs on a variety of complex flow simulation models - fine-cellular and full-scale. The outcome of the study was the creation of a new development concept which provides different design solutions for under-gas-cap and water-oil zones. The value of the work lies in the fact that the decisions involve different oil displacement processes in different parts of deposits, which affects the oil recovery rate and as a consequence the whole field development and infrastructure complex.