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对于水平井井筒的稳定单相流动，提出了水平井井筒管流的“微元段”观点，从而简单实用地解决了井筒内的变质量流问题；根据流体力学和渗流力学理论，给出了水平井井筒管流的“等效渗流”方法，推导了单相流动的层流、紊流和过渡状态时的“等效渗透率”，建立了水平井井筒的“管流等效渗流”模型。当水平井井筒内流动处于层流状态时，等效渗透率仅是井筒半径的函数；当流动处于紊流状态时，等效渗透率不仅是井筒半径的函数，而且与流体性质以及井筒压降有关。经实例分析，模型计算所得的等效渗透率在不同流态时是连续的，避免了流态转化时的数值突变问题，而且模型简单实用，所得到的等效渗流方程与达西渗流方程形式相同，因此，现有的用于处理油藏渗流的技术都可以用在井筒管流中。该模型可以在井筒管流与油藏渗流耦合问题中使用，避免了在耦合过程中使用繁琐的流体力学公式，从而可以降低耦合问题的复杂性，使求解问题变得简单。
For the steady single-phase flow in horizontal wellbore, a “micro-section” view of horizontal wellbore flow is proposed to solve the problem of variable mass flow in wellbore simply and practically. According to fluid mechanics and seepage mechanics theory, The “equivalent seepage” method for horizontal wellbore pipe flow derives “equivalent permeability” of single-phase flow in laminar flow, turbulent flow and transitional state, and establishes a “pipe flow equivalent seepage flow” model for horizontal wellbore . Equivalent permeability is only a function of the wellbore radius when the flow in a horizontal wellbore is laminar; when the flow is in a turbulent state, the equivalent permeability is not only a function of the wellbore radius but also the nature of the fluid and the wellbore pressure drop related. The case study shows that the equivalent permeability calculated by the model is continuous at different flow regimes and avoids the problem of numerical sudden change in the flow regime transformation. Moreover, the model is simple and practical. The obtained equivalent seepage equation and Darcy flow equation form Therefore, the existing technologies for treating reservoir seepage can all be used in wellbore flow. The model can be used in the wellbore pipe flow and reservoir seepage coupling problems, and avoids the complicated fluid mechanics formula used in the coupling process, so that the complexity of the coupling problem can be reduced and the problem of solving the problem can be simplified.