The article is devoted to the formation of a conceptual approach to the development of floating oil fringe of the Valanginian deposits of the Yaro-Yahinskoye field through the usage of horizontal and multilateral wells. A feature of the geological structure of the main productive deposit of the Yaro-Yahinskoye field
(BT7-8) is a layered reservoir with high heterogeneity of the filtration properties due to the features of formation (fluvial delta). Secondary post sedimentation processes such as leaching of feldspar complicates the existing geology, which leads to the formation of lateral anisotropy of the reservoir properties.
The adopted design solution for the development of this oil fringe is the drilling of horizontal wells according to the selective system. Development of the reservoir is on depletion mode with a fountain method of wells operation. Drilling and development of horizontal wells at the stage of pilot works showed the level of the starting water cut is much higher than planned, which led to the adjustment of both the geological structure of the reservoir in terms of saturation, and to the adjustment of the strategy of horizontal wells drilling. Oil saturated reservoir interval of the oil rim divided into three saturation regions: limit oil saturation zone, the zone of transient saturation and the limit zone of water saturation. Controlling factors in the spread of these zones are the geological features of the reservoir BT7-8: contrast of layers properties, the reservoir structure (hypsometric position of the reservoir) and the leaching of feldspars. The forecast of the influence of the first two factors, taking into account the high density of exploration drilling, is quite high in contrast to the last factor of secondary changes in the formation due to the low characterization with the core in the area of the productive formation. In this regard, the strategy of drilling horizontal wells has been adjusted. It was offered to apply MDT technology and sampling to correct drilling corridor of horizontal wells. In addition, to reduce the risks of accelerated formation of water and gas cones in the floating oil fringe of the BT7-8 layer of the Yaro-Yahinskoye field, it is proposed to use drilling of multi-hole wells, which will also increase the oil production and reduce the working depression on the reservoir.
