相对渗透率（kr）和毛细管压力（Pc）是定义多孔介质中多相流体流动行为的关键因素。然而，在极低渗透地层中进行注水过程时，动态毛细管现象应考虑动态相对渗透率和动态毛细管压力。为了提高石油产量，通常采用先进的水平井钻井和多次水力压裂来开采非常规资源。本研究的目的是在商业油藏模拟中考虑动态毛细管现象，同时利用从非常规致密油藏岩心塞注水过程中相对渗透率和毛细管压力影响的动态和稳态实验中获得的数据。使用CMG商业油藏模拟进行了敏感性分析。结果表明，在采用稳定数据进行预测的同时，储层的井产量被高估了，因此含油饱和度下降得更均匀、更快。此外，对油井产量的预测预计将早日突破。然而，忽略了动态毛细管现象导致了水侵的巨大突破。因此，本研究的核心目标是探讨考虑超低渗透地层中动态毛细管现象的后果，同时为预测水力压裂非常规致密油藏的产量提供另一种视角。
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.
以下是CMG进行的数值模拟得出的主要结论，该模拟旨在研究水力压裂非常规致密地层中动态毛细管现象在整个注水过程中的作用：
1.如果采用稳定毛细管现象来预测注水效果，则毛细管压力分布更均匀，毛细管阻力更小，含油饱和度降低更均匀、更快。
2.如果用稳定毛细管现象代替动态毛细管现象，则地层的井产量被高估，预测的采油率将更快突破，从而导致水侵突破更大。
3.在水力压裂的非常规致密油藏中，有必要考虑动态毛细管现象。这项工作为预测水力压裂非常规致密油藏的产量提供了另一种观点。