相对渗透率（kr）和毛管压力（Pc）是定义多相流在多孔介质中流动行为的关键要素。然而，在极低渗透率的储层中进行水驱过程时，应考虑动态相对渗透率和动态毛管压力。为了提高采油量，通常会采用先进的水平井钻井和多级水力压裂来开采非常规资源。本研究的目的是在商业储层模拟中考虑动态毛管力，同时利用非常规紧油储层岩心塞水驱过程中相对渗透率和毛管压力影响的动态和稳态实验数据。利用计算机模拟软件集团模拟器进行了商业储层模拟和敏感性分析。结果显示，使用稳态数据进行预测时，储层的井产量被高估，导致油饱和度更均匀且更快地下降。此外，预测的井产量预计会更早突破。然而，忽略动态毛管力会导致大量水涌入。因此，本研究的核心目标是探讨在超低渗透率储层中考虑动态毛管力的影响，并为预测水力压裂非常规紧油储层的产量提供另一种视角。

CMG软件应用情况

在本研究中，CMG（Computer Modeling Group）软件被用于模拟非常规紧油储层的水驱过程。研究人员利用CMG的IMEX模块对目标储层的五点法水驱模型进行了模拟。该模型考虑了水力压裂的影响，将压裂区域视为独立的流动系统。输入参数包括储层的几何尺寸、基质和压裂的渗透率、孔隙度、流体性质、注入压力等。通过CMG软件，研究人员能够模拟不同条件下的水驱过程，分析稳态和动态毛管力对储层产量的影响。

结论

  1. 采用稳态毛管力预测水驱效果时，毛管压力分布更均匀，毛管阻力较小，油饱和度下降更均匀且更快。
  2. 用稳态毛管力代替动态毛管力时，储层的井产量被高估，预测的油回收会更早突破，导致更大的水涌入。
  3. 在水力压裂的非常规致密油储层中，考虑动态毛管力是必要的。本研究为预测水力压裂非常规紧油储层的产量提供了另一种视角。

Simulation study of relative permeability and the dynamic capillarity of waterflooding in tight oil reservoirs

Abstract

Relative permeability (kr ) and the capillary pressure (Pc) are the central key elements defining the multiphase fluids flow behavior in the porous media. However, the dynamic capillarity should consider the dynamic relative permeability and the dynamic capillary pressure while performing waterflooding process in extremely low permeable formations. In order to improve the oil production, the advanced horizontal well drilling along with multiple hydraulic fracturing is generally instigated to penetrate the unconventional resources. The aim of this study is to consider the dynamic capillarity in a commercial reservoir simulation, while utilizing the data gained from the dynamic and steady experiments of the relative permeability and the capillary pressure impacts during waterflooding process in the core plugs of unconventional tight oil reservoirs. The commercial reservoir simulation conducted sensitivity analyses using Computer Modeling Group simulator. The outcomes show that the well production of the reservoir is overestimated while implementing steady data for forecasting due to which the oil saturation decreases more equally and further rapidly. Additionally, the forecast of the well production estimated to breakthrough sooner. However, neglecting the dynamic capillarity causes a huge breakthrough of water influx. Therefore, the core objective of this study is to probe the consequences of taking into consideration the dynamic capillarity in ultralow permeable formations while giving an alternative perspective to forecast the production of the hydraulically fractured unconventional tight oil reservoirs.

Keywords

Dynamic · Steady · Capillary · Relative permeability · Waterflooding

Conclusions

Following are the major conclusions from the numerical simulation conducted by CMG to investigate the role of the dynamic capillarity throughout the waterflooding procedure in hydraulically fractured unconventional tight formations:

1. If the steady capillarity is adopted to predict the waterflooding performance, the capillary pressure distributes more uniformly, and the capillary resistance is smaller, with a more even and quicker reduction in the oil saturation.

2. If the steady capillarity is used to replace the dynamic one, the well production of the formation is overvalued and the predicted oil recovery will breakthrough sooner causing a greater breakthrough of water influx.

3. It is necessary to take into consideration the dynamic capillarity in hydraulically fractured unconventional tight reservoirs. This work gives an alternative standpoint to forecast the production of the hydraulically fractured unconventional tight oil reservoirs.

 

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