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Efficient Modeling Of Near Wellbore Phenomena For Large Scale Gas-Condensate Systems In Massively Parallel Reservoir Sim
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, ECMOR XVI - 16th European Conference on the Mathematics of Oil Recovery, Sep 2018, Volume 2018, p.1 - 16
Abstract
Gas condensate reservoirs exhibit complex behaviour when they are produced below dew point pressure under isothermal conditions; this is due to the appearance of a two-phase gas-condensate in the near wellbore region. In addition, at high flow rates in the near wellbore region, inertial forces counteract with velocity dependence of relative permeability. This behaviour can be resolved using local grid refinements; however, the computation burden becomes excessive, especially in a full field simulation. Alternatively pseudo-pressure approach can be used which iteratively solves a non-linear equation at each integration point, and is also computationally expensive. Furthermore, the conventional pseudo-pressure method lacks efficient coupling of the complex interaction of fluid composition, liquid dropout rate, gas-oil relative permeability, gas-oil interfacial tensions, and non-Darcy flow effects. Development of a computationally efficient and accurate approach to model near wellbore phenomena without increasing grid resolution is presented. An adaptive piecewise representation of pseudo-pressure is used, replacing non-linear equation solved at each integration point, thus drastically reducing computational cost without undue loss of accuracy. Non-Darcy flow effects and interaction of rock and fluid properties are captured in the pseudo-pressure integrand in a unified manner. The results are validated against a commercial simulator, and fine grid results, which demonstrate the accuracy and consistency of the approach. Finally the efficiency of the approach is demonstrated by simulating a giant gas-condensate model with thousands of wells and millions of cells, all solved on a massively parallel computer.