Performance of vertical and horizontal wells drilled in carbonate reservoirs of Korobkovsky area in the Bavlinskoye field has been analyzed. Geological model was used to predict production data in case of injected water diversion to the lower part of a productive formation.
To define an optimum carbonate reservoir development strategy, pilot areas were selected in the Kizelovsky horizon in the middle 80s, which were developed with different well patterns and spacing. Field data proved the efficiency of carbonate reservoir development using waterflood techniques that ensured reservoir pressure stabilization, lower rate of water invasion, and maintenance of commercial production as against other pilot areas developed by depletion.
Since 2001, a new integrated production system has been introduced in the Kizelovsky horizon of Korobkovsky area involving cluster drilling of water-supply wells followed by drilling of injection and directional production wells. As of 2016, 212 wells have been drilled in this area, including 172 producers (101 vertical and 71 horizontal wells) and 40 injectors. All of the wells are on-stream now.
The experience of producing marginal reservoirs in Tatarstan fields suggests that one of the most efficient development systems involves using a combination of production (vertical and horizontal), injection and water-supply wells.
To attain maximum oil recovery in Korobkovsky area, we suggest improving the injection wells performance through diverting the injected water to the lower part of the formation in each injector, 1-2 m above the bottom of the lower oil-saturated layer. To solve this issue, a geological model of Korobkovsky area was developed to predict production data in case of diverting the injected water. Predicted results show that water diversion in injection wells improves waterflood system efficiency – oil rates increased by 1.9-2.3 t/d, water-oil ratio decreased from 0.131 to 0.122, and oil recovery factor increased from 0.021 to 0.153.References
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