The comprehensive approach to formation of conceptual versions of the offshore oilfield development in the Arctic seas at preliminary stages of design is considered in the paper. With this purpose, the algorithms and the system of formation of integrated structures in all systems intended for the oilfield development are designed, with " support structure" and " vertical wall". The special attention is paid to decision-making on choice of the least material-demanding variant of the leg basis of an offshore oil-and-gas extraction platform. Result of calculation is the optimum variant of the offshore oilfield development.
The system may be used for evaluations of technical and economic parameters in the oilfield development at stages of assessment of feasibility of the project or the feasibility report.
According to the experts' estimations, all Arctic seas of the Russian Federation contain hydrocarbon resources (Fig. 1). The natural conditions of these seas are characterized by considerable variety and severity. Therefore, alone with many other factors, this outlines properties and types of engineering means used for development of offshore hydrocarbon fields. And main difficulties with development of offshore fields within the northern seas using equipment and technologies approved for ice-free seas are mostly related to the severe natural conditions.
As for offshore fields development within ice-free seas (shelf of the Gulf of Mexico, the South America and Africa shelf), water depth and influence of sea waves within the development area are the main factors which determine types and parameters of engineering means and equipment used for offshore oil and gas production. Based on the main force factor determining their stability, these engineering means and equipment can be classified as wave-resistant.