变形介质低渗透油藏油井真实产能计算与分析

Calculation and analysis of the true productivity of a well of low permeable reservoirs of deformation medium

基于变形介质带启动压力梯度低渗透油藏稳定渗流理论,研究了低渗透油井增产措施后稳定生产的真实压力分布与产能分析方法.研究结果表明低渗透油藏油井渗流场的真实压力分布具有分区域特征;在具有变形介质特征的低渗透油藏中,油井的产能随启动压力梯度和介质变形系数增大而降低,随增产激活半径和激活系数的增大而增加,随生产压差的增大而增加;同时油井产能指数随生产压差增大呈非单调增曲线,因此对于低渗透油井生产而言,存在合理生产压差与最小生产压差.同时,沿用同一思路对超低渗透油藏开发的有效途径进行了探讨.认为提高增产激活半径是显著提高超低渗透油藏产能的有效方法.理论计算结果表明,只有在增产激活半径大于60m(渗透率越低,该值越大)时油井的产能才会得到大幅度提高.因此,寻求深穿透的油井改造措施或采用水平井开采技术,将是超低渗透油藏开发的有效方法.

The true pressure distribution and the productivity analysis method of a stable-producing low-permeability well after stimulating measures are studied based on the stable percolation flow theory for the low permeability reservoir of the deformation medium with start-up pressure gradient. The results show that, the true pressure distribution in the percolation flow field of the low-permeability well possesses two regional features; in the low-permeability reservoir of deformation medium, the productivity of the stimulated well decreases with the increases of start-up pressure gradient and medium deformation factor, increases with the increases of the active radius and the active factor of the well, and increases with the increase of production pressure difference; the productivity index of the well presents a non-monotone increasing curve with the increase of production pressure difference, therefore there are not only a rational production pressure difference but also a minimum production pressure difference. The effective approaches to develop super-low permeability reservoirs are discussed using the same thinking. It is held that increasing the active radius of the stimulated well is an effective approach to enhance the productivity of super-low permeability wells. The theoretical calculation results show that, the productivity of the well is greatly enhanced only when the active radius of the well is greater than 60 m. Therefore, deep well stimulating measures or horizontal well technique should be applied in the development of super-low permeability reservoirs.