多油层油藏均衡开采影响因素分析

Analysis on influencing factor of balanced development for multilayered reservoir

不均衡开采是多油层油藏开发存在的主要问题。基于油藏渗流模型和井筒流动模型,根据压力的连续性条件,建立了多油层油藏￣井筒流动耦合的半解析模型,给出了多层合采直井的产液剖面和压力剖面计算方法,定量计算并分析了井筒压力损失、层间渗透率差异、原油黏度差异、压力差异和层间距离对多层合采直井均衡开采的影响。结果表明:层间压力差异对多油层油藏直井均衡开采的影响最大,在其他参数相同的条件下,层位地层压力越大,相应产量越高,当合采油层间的压力差异大于生产压差时,有可能出现窜流;层间渗透率差异影响次之,在其他参数相同的条件下,各层段的产液量只与层位间的渗透率比值有关,而与渗透率的具体大小无关;层间原油黏度差异相对较小,井筒压力损失的影响可以忽略。该研究对多油层油藏的开发效果预测以及完井方案优化设计具有指导意义。

Unbalanced development is the main problem of multilayered reservoir. Based on reservoir percolation model and wellbore flow model, a multilayered reservoir-wellbore coupling model is developed according to pressure consistency. The calculation method of fluid producing profile and pressure profile for the balanced development of vertical wells with multilayered commingled production is given. On this basis, the influence of wellbore pressure loss, interlayer permeability difference, oil viscosity difference, pressure difference and interlayer distance on the balanced development of vertical wells with multilayered commingled production is analyzed qualitatively. The results show that the interlayer pressure difference has the greatest influence on balanced development. Under the same condition of other parameters, the greater the horizon formation pressure is, the higher the production is. When the pressure difference between oil layers is greater than the production pressure difference, fluid channeling may occur. The interlayer permeability difference has secondary influence. Under the same condition of other parameters, the produced fluid volume of intervals is only related to the permeability ratio between horizons and has nothing to do with the concrete size of permeability. The viscosity difference of crude oil is relatively small. The influence of wellbore pressure loss can be ignored.This study has guiding signification for the production prediction and scheme design of well completion.