WAG simulation on Ach test area Vostochno-Perevalny oilfield

In this paper presented results of mathematical simulation of WAG on Vostochno-Perevalny oilfield (East dome) of Western Siberia, where were conducted field WAG trials by Ritek since December 2008. The aim of this work is creation the digital and hydrodynamic model and choice an option to development a test area of Vostochno-Perevalny oilfield with application results of core research and taking into account hysteresis effects of relative permeability and role of occluded gas. It were adduced the arguments to application the WAG method to increasing oil recovery and APG utilization.
Materials and methods
Simulation, industrial experiment works.
Results
It was chosen more optimal variants of WAG to obtaining maximum oil recovery during WAG.
Сonclusions
1. It was found that the best option for injection is water-gas mixture with the following parameters: water and gas ratio =0.005 at the gas content = 36% and water gas ratio = 0.01 at gas content = 22%.
2. Achieved precalculated extra oil recovery (comparison on water flooding) is more than 70000 m 3.
3. Incremental of oil recovery rate is 2,5% in WAG taking into account hysteresis of relative permeability on base period with comparison on water flooding.
4. It is shown that taking into account hysteresis effects of relative permeability and occluded gas in reservoir, the frontal advance is more uniform, also if is there more filtration resistance of mixture. For more uniform and permeable collector accounting the hysteresis of relative permeability leads eventually to an increase in oil recovery by 3-4 percentage points by increasing the sweep.
5. The full-scale model of the reservoir due to the high inhomogenuity of the pores (mainly low permeability) the part of reservoiris disconnected from the development because of occluded gas, and express filtering occurs mainly in highly permeable streaks, albeit with the best coverage, but only on the part of the collector.
6. Calculation, conducted without taking into account hysteresis of relative permeability, leads to incorrect increasing the hysteresis effects of relative permeability for gas after water injections.
7. Analysis of calculations with water injection periods shown, that the option with WAG and 3 years period has smaller injection volume and maximum oil recovery rate.