Rosneft Started Developing Hard-to-Recover Reserves from the Preobrazhensky Horizon
The Verkhnechonskneftegaz company, which is part of the oil and gas production complex of NK Rosneft, has begun pilot work to develop hard-to-recover reserves of the Preobrazhensky horizon at the Verkhnechonskoye oil and gas condensate field. The cycle of hydrodynamic and geophysical studies to assess the production potential of the reservoir will last for three years, until 2023.
The Preobrazhensky horizon is located at a depth of 1600 meters, above the Verkhnechonsky horizon, which is the main development target for Verkhnechonskneftegaz. It is represented by a carbonate reservoir and is characterized by extremely low reservoir permeability. Initial recoverable reserves amount to over 28 million tons of oil. The oil-bearing area of the Preobrazhensky horizon extends far beyond the Verkhnechonskoye field into several license areas in the Irkutsk region.
The first two wells were launched in August 2020. The start-up flow rate of the first horizontal well with multilateral wellhead was 113 tons per day, the second – with multi-stage hydraulic fracturing – 51 tons per day. The obtained result showed the effectiveness of the proposed methods, since for a long period of selection of technologies on the Preobrazhensky horizon, it was possible to obtain from the reservoir no more than 10 tons per day from one well.
In total, six wells were drilled within the framework of the project to develop hard-to-recover reserves of the Preobrazhensky horizon. In order to achieve the maximum production rate, all wells were drilled in the zones with the best reservoir permeability. For this, a complex of geophysical surveys of wells during drilling was used, which allows real-time determination of the properties and saturation of the formation and, if necessary, correct the direction of drilling. To ensure the most high-quality reservoir penetration, all wells were drilled using oil-based mud.
