中文摘要：

根据单一启动压力梯度的低渗透油藏直井产能公式，分别考虑污染区与未污染区压裂后的渗透率和相应的启动压力梯度变化，建立分区考虑启动压力梯度的低渗透油藏污染井压裂增产新模型。结果表明：污染区内外的启动压力梯度差别较大．考虑污染区内外不同启动压力梯度的低渗透油藏污染井产能预测模型更符合实际情况；考虑污染区内外不同启动压力梯度所计算的产能比没有考虑启动压力梯度的产能要小得多，对于压裂井，启动压力梯度的影响较小。

英文摘要：

Firstly, the productivity formula of vertical well was deduced considering single starting pressure gradient in low permeability reservoir. Then the changes of permeability and starting pressure gradient of contaminated zone and uncontaminated zone after fracturing were analyzed. A new fracture stimulation model was established considering different starting pressure gradient in contaminated and uncontaminated zone for contaminated wells in low permeability reservoir. The results show that the starting pressure gradients of contaminated and uncontaminated zone are of great difference, this production forecasting model of contaminated well is more consistent with the actual situation. The productivity considering two starting pressure gradients is lower than that without considering starting pressure gradient. The starting pressure gradient has less influence on fracturing wells.