Enhancing oil recovery (EOR) and maintaining sustainable production rates are very important aspects in the development of mature fields where most prolific producing zones are developed at earlier stages.
Back in 1969, initial production operations in the Tan-Kandyzskoye field were targeted at Pashian reservoirs and involved peripheral water injection followed by boundary waterflooding. Adequate reservoir management strategy enabled not only to prevent rapid increase of water cut but also to suppress reservoir pressure depletion. Peak oil production was achieved in 1972 with the subsequent production decline observed since 1982. Decreased oil flow rates were attributed to water cut increase and deteriorated quality of residual Pashian reserves. Cessation of any further drilling in the early 1990s also slowed down the rates of field development. Further, 2004 has witnessed an increase in oil production and substantial decrease of average annual water cut due to drilling through Bobrikovian, Kizelovskian, and Vorobievian production zones, successful implementation of dual completion technology, optimization of waterflood pattern in the Pashian formation, water injection in other production zones, revitalization of idle wells, and selective application of various physical and chemical methods. These helped recover in 2015 42% of peak oil production obtained in 1972.
The following activities are proposed for efficient development of residual oil reserves: further drilling in oil-saturated areas of production zones, sidetrack drilling, continued use of dual completion method, optimization of waterflooding program, including initiation of water injection in the Kizelovskian production zone. Depending on bedding conditions and reservoir quality, well-proved effective EOR methods are recommended.
