The article provides a complete study of the possibility of simultaneous development of several formations by one object only with the same physical and chemical properties of oil in the combined formations, if the inflow of oil and gas is sufficient from each formation at an acceptable bottom-hole pressure in the well, with close values of reservoir pressure in the combined formations, excluding oil flows between the layers, and close values waterlogged formations. It also describes the field experience of operating several layers with one well by the method of dual completion (DC), indicating its high efficiency. On average, capital investments and operating costs are reduced by 30% in comparison with the costs of drilling and operating fields with independent grids for each formation. The DC method is cost-effective and makes it possible to seal the grid of wells (producing and injection) without additional drilling footage. 0the integration of productive formations into operational facilities leads to a significant reduction in the volume and timing of drilling of the field, saving material resources for the development of fields. At the same time, during joint operation, as a rule, the conditions for the development of each individual reservoir deteriorate, it becomes difficult to control and regulate the operation process. In these cases, the method of dual completion is used, through which a differentiated effect is carried out on the formations developed jointly by one well grid. Dual completion is a means that, with economical joint operation, ensures optimal conditions for the production of oil reserves of each reservoir and thereby increases the economic efficiency of their development. Technological efficiency is understood as an increase in the rate of production of reserves and the oil recovery coefficient of each formation of a multi-layer facility by regulating the operation processes. At the same time, the movement of water-oil and gas-oil contacts and the coverage of the reservoir by displacement in power is regulated. Dual completion in domestic practice and abroad is carried out by equipping wells with special equipment for separation of layers or using wells of special designs for these purposes.