Abstract Accumulation of liquids in gas-condensate reservoirs may lead to a vertical flow of liquid caused by density difference in the presence of gravity. In this paper, the effect of this vertical flow on the prediction of production data has been investigated. To achieve this goal, a single-layer synthetic cylindrical reservoir is considered and, the flows are simulated with and without vertical direction grid blocks with two lean and rich fluids. The governing equations of the so-called Modified Black-Oil (MBO) model are solved in a cylinder sector using the open-source Matlab Reservoir Simulation Toolbox (MRST). When the vertical flow is taken into consideration, the results show that gravity may lead to migration of liquid condensates to lower regions and the production rates decrease as a consequence of wellbore partially blockage especially for the rich fluid. In addition, gravity may cause a non-linear effect on the flow behavior and increase in the condensates production rates. All results are also obtained for three values of critical liquid condensate saturation to show the effect of this parameter on the production. It has been shown that neglecting the vertical flow may cause significant errors in the result of production, i.e. up to 25% when the fluid is rich and the critical condensate saturation is 0.15. To generalize the effect of the reservoir thickness, dimensional analysis is carried out which yields a similarity parameter. The findings of this study can help for a better understanding of near well flow in gas-condensate reservoirs. Based on this study, in applications in which the reservoir gas is rich in condensate and the thickness of the reservoir layer or the vertical permeability is high enough, it is recommended that the gravity effect is taken into account by enough grid points in the vertical direction in each layer.

中文翻译：

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凝析气藏生产井附近凝析液垂向运移研究

摘要 凝析气藏中液体的聚集可能导致重力存在下密度差引起的液体垂直流动。本文研究了这种垂直流对生产数据预测的影响。为了实现这一目标，考虑了一个单层合成圆柱油藏，并在有和没有垂直方向网格块的情况下模拟了具有两种贫流体和富流体的流动。使用开源 Matlab 油藏模拟工具箱 (MRST) 在圆柱扇区中求解所谓的修正黑油 (MBO) 模型的控制方程。当考虑垂直流时，结果表明，重力可能导致液态凝析油迁移到较低的区域，并且由于井筒部分堵塞，尤其是富流体，产量会降低。此外，重力可能会对流动行为产生非线性影响并增加冷凝物生产率。还获得了三个临界液体凝析油饱和度值的所有结果，以显示该参数对产量的影响。研究表明，忽略垂向流动可能会导致生产结果的显着误差，即当流体富集且临界凝析油饱和度为0.15时，误差可达25%。为了概括储层厚度的影响，进行了产生相似参数的量纲分析。这项研究的结果有助于更好地了解凝析气藏中的近井流动。基于此研究，在储集气富含凝析油且储集层厚度或垂直渗透率足够高的应用中，建议在垂直方向通过足够多的网格点来考虑重力效应。在每一层。