This paper summarizes practical results of oil fields development by multilateral horizontal wells. By the example of Severo-Yangtinskoe and Chatylkynskoe oil fields the whole cycle of works from well-planning to development monitoring is described. Severo-Yangtinskoe is one of the newest oil fields operated by the Company. Field Development Project regulating its development was drawn up and approved in Central Development Commission in 2006 after that production drilling of the main object began. All project decisions are based on reservoir simulation model. According to FDP, development scheme involves irregular placement of horizontal and subvertical wells. Severo-Yangtinskoe reserves may be classified as difficult to recover; in practice it is problematic to involve such a deposit into development by conventional subvertical well schemes. During the two-year period of field development 8 horizontal wells have been successfully drilled and put on production, of which 3 are multilateral, that is the latest well completion technology probe-tested in the Company. This technology has been put into practice on the other Company's oil fields. Present work demonstrates and proves the advantages of complex reservoirs development by dual horizontal wells. Chatylkynskoe oil field is also one of the newest Company's assets. FDP regulating the development was composed and defended in Central Development Commission in 2006. The pilot project specifies horizontal wells application as well as marginal waterflooding by deviated wells for the field development. The main reservoir has significant thickness, but its geological structure is complicated by tectonic disturbances and heterogeneity. All the decisions worked out are based on a reservoir simulation modeling. During the period 2006 - 2008 7 horizontal wells have been successfully drilled, 5 of which are dual wells. General oil fields description Severo-Yangtinskoe oil field belongs to Purovskij district of Yamalo-Neneckij autonomous okrug, Tyumen region, and is situated in the territory with well-developed infrastructure. (Fig.1) In immediate proximity to Severo-Yangtinskoe field Umseyskoe and Muravlenkovskoe oil fields, operated by the Company, are situated. The area is located 32 kilometers south of Muravlenko town. Industrial oil-bearing capacity of Severo-Yangtinskoe is determined in the terrigene sediments of Megion formation, Lower Cretaceous age, and related to layers BS10 1, BS10 2, BS11 and BS10 2–0, regionally productive in Noyabrsk region. The deposits may be classified as massive, layer-uplifted and lithologically screened. The main reservoir is layer BS11, discovered in 1985 and proved by exploration wells 300R, 301R and 314R testing. Geological structure of layer BS11 is quite complex, net pay thickness of the reservoir ranges 16.6 - 1.1m (fig. 2).

For regulation and management of development process of oil and gas fields on them various kinds of researches are continuously spent. In a complex of these researches the main

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