渤海多层油藏聚合物驱注入能力研究

Study on the injection capacity of polymer flooding in Bohai multi-layer oil reservoir

为了更有针对性地评价渤海多层油藏聚合物驱的注入能力,考虑聚合物非活塞驱替过程中流体饱和度的分布特征以及开发井网条件下多油层纵向非均质性的影响,对已有的聚合物驱注入能力数学模型进行了改进。首先,基于聚合物驱分相流理论,求解驱替过程中各流动区域前缘饱和度及相关参数大小,建立了聚合物驱替含水饱和度分布模型;其次,应用等值渗流阻力法,推导出注采井间渗流压差的计算表达式;最后,考虑开发井网条件下多油层纵向非均质性的影响,对分层流量及注入能力进行表征,建立起多油层聚合物驱拟三维两相三组分注入能力解析解数学模型。模型求解结果与实验数据吻合程度较好,验证了该计算方法的合理性。本文建立的数学模型可用于预测及评价多层聚合物驱油藏在不同开发阶段合层及分层的注入能力,为渤海油田聚合物驱注入体系的有效评价提供了一种新方法。

To evaluate the injection capacity of polymer flooding in Bohai multi-layer oil reservoir specifically,the existing mathematical model for the injection capacity of polymer flooding was modified.In this modified model,the distribution characteristics of fluid saturation in the process of non-piston like poly displacement and the effects of vertical heterogeneity of multiple oil layers in the development well pattern are taken into account.Firstly,the frontal saturation of each flow zone and its related parameters in the process of displacement are calculated according to the fractional flow theory of polymer flooding,and the water saturation distribution model for polymer flooding was established.Secondly,the expression used to calculate the seepage pressure difference between injectors and producers was derived.And finally,considering the effects of vertical heterogeneity of multiple oil layers in the development well pattern,the layered flow rate and the injection capacity were characterized,and the pseudo-three dimensional,two-phase,three-composition analytic solution mathematic model for the injection capacity of polymer flooding in multiple oil layers was developed.The calculation results are in accordance with the experimental data,indicating the rationality of this calculation method.The mathematic model established in this paper can be used to predict and evaluation the commingled and layered injection capacity of multi-layer polymer flooded oil reservoirs in different development stages and it provides a new method for evaluating effectively the injection system of polymer flooding in Bohai Oilfield.