The fields in the northern part of the Caspian Sea are characterized by a complex geological structure, which increases the level of uncertainty and risks associated with the planning and drilling of production wells. These problems are most evident in the development of fields with a thin oil rim, where the position of the profile of producing wells in relation to fluid contacts and fracture failures becomes critical for subsequent production. The experience of drilling in this region shows that even in the case of brown fields, there are areas with high structural and lithological uncertainties, which require additional geological study before making decisions on drilling of new production horizontal wells. If a significant area of the field needs to be further explored, drilling of a vertical or inclined pilot hole is often a common practice in the industry may not be informative in compartmentalized reservoirs. In such conditions, it seems reasonable to use extended horizontal wells as pilot holes, as it will allow to obtain information about the geological structure from a much larger area.

In the case of horizontal pilot hole drilling through the reservoir rocks within the oil-saturated zone, it is possible to determine the position of the top and bottom either by fluctuations of the trajectory between the reservoir boundaries or by application of ultra-deep electro-magnetic methods of geological section imaging.

The paper presents the method of drilling ERD horizontal pilot sections with the use of the latest technologies in local exploration of structural plan, which is well established for detailed improvement of the geological model, under the condition of its integration with seismic data, as well as for the estimation of residual reserves for planning new production horizontal wells.

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