考虑井筒压降的水平井流速及压力分布研究

Research on flow velocity and pressure distribution of horizontal well considering wellbore pressure drops

针对井筒摩擦和加速度对井筒压降的影响,根据质量守恒定律和动量定理推导了水平井筒内压降计算的基本公式,建立了与油藏耦合的水平井沿程流速与压力分布计算模型。求解该模型可以得到考虑井筒压降的水平井沿程流速与压力分布。研究发现:水平井水平段沿程压力靠近趾端变化较小,靠近跟端变化较大;由于径向入流的存在,使得水平井沿程呈现变质量流的特点,水平井沿程流速从趾端向跟端增加;水平井产能与流体密度、流体黏度和水平井距油藏底部距离等参数呈负相关关系,与水平井井径、生产压差、渗透率和油藏厚度等参数呈正相关关系。

Pressure drops in horizontal wellbore have great influence on the production performance of horizontal well.This paper considered the influence of wallbore friction and accelerationon on pressure drops in horizontal well.Based on the principle of mass conservation and momentum,the mathematical model calculating the pressure distribution and flow velocity of horizontal well coupled with reservoir was built.The pressure distribution and flow velocity of horizontal well can be calculated by solving the model.The study shows that the pressure change in the toe section is small along the horizontal direction and the pressure change near the heel section is great.Due to the existence of radial inflow,the horizontal well appears the feature of variable mass flow and the velocity along the horizontal direction increases from toe section to heel section.The productivity of horizontal well is negatively correlated with the fluid viscosity,the fluid density and the distance from horizontal section to the bottom of the reservoir.It is positively correlated with the well diameter,production pressure difference,permeability and reservoir thickness of horizontal well.