分段射孔水平注水井注入动态研究

水平井分段注水时，在总注入量确定的情况下，确定每个射孔段的流量分配与压降分布是一个复杂且有现实意义的问题。建立封闭地层的水平井三维稳态渗流模型，用Fourier 正弦变换、势的叠加原理、三角函数变换、渐进分析求解其压力和流量分布；通过与直井比较，求得均匀流量水平井稳态当量井径模型。利用多井叠加原理建立分段射孔无限导流水平井流量分配模型，用高斯消元法求取每个射孔段的流量分布，在此基础上分析了分段射孔水平注入井的压降特征。算例应用表明，在其他条件相同的情况下，射孔间距或射孔段长度越大，射孔段附近压降越大，而水平井中部的射孔段附近的压降小于相同条件下端部射孔段的压降；分段射孔水平井的近井地带易于形成近线性驱替系统，特别是选择中间略长，根（趾、端）部稍短的射孔方式，可使这种驱替效果更好。该方法能够直观量化每个射孔段注水量的分配，从而为周围油井注水见效、水驱动用程度等的分析奠定基础。

Study on injection performance of horizontal water injection well with segmental perforation

It is very diffcult but valuable to determine the injection rate and pressure drop distribution of each perforation interval at given injection rate at surface.This paper develops a 3D steady state flow model of horizontal wells in closed reservoir.And the Fourier transform, principle of potential superposition, trigonometric function transform and asymptotic analyses are used to solve its solution of pressure and rate distribution.Compared with injectivity of vertical wells, an equivalence radius model of horizontal wells with uniform flux can be obtained.By the use of multi-well superposition principle, the paper also develops a flow distribution model of horizontal wells with segmental perforation and inflnite conductivity, and obtains flow rate distribution in each perforation interval by Gaussian elimination.Then it analyzes the pressure drop of horizontal injection wells.Vital example demonstrated that a longer interval or length of perforation interval always has a larger pressure drop around it when the other conditions are identical.The pressure drop around the interim interval is little smaller than that in the end intervals in same condition.The near wellbore zone in horizontal wells with segmental perforation is easily to form near linear displacement system, especially with such perforation mode that interim interval has a larger length than that of end intervals.This method can quantify the injection rate of each perforation interval, laying a foundation for the analysis of injection effect and producing degree of surrounding oil wells.