As an important stimulation technology, refracturing is commonly used to enhance oil or gas recovery in tight reservoirs, particularly for poorly/damaged fractured wells in these reservoirs. However, the stimulation effect of refracturing is not clear at present. Accurate evaluation of the effect of refracturing treatment on the productivity of a poorly/damaged fractured well is of great significance to the rapid and efficient development of tight reservoirs. In this study, two semi-analytical models, including an initially fractured well model and a refractured well model, were established to calculate their productivity indices, respectively, for quantitative productivity evaluation. Productivity index ratio, a newly defined parameter reflecting the characteristics of both productivity indices, was calculated to evaluate the refracturing stimulation effect. The comparisons with two classic cases indicated our solutions were exactly consistent with the results in the previous literature and verified the reliability and accuracy of our solutions. Results show that compared with initially fractured well, the productivity of refractured well first rises rapidly and then slows down as principal/reoriented fracture angle or rotation angle increases, but an inverse relationship may occur at low initial fracture conductivity. Meanwhile, the productivity index ratio curves under the same initial fracture conductivity converge into a bunch of curves, first increasing and then slowing down as reorientation fracture conductivity enhances. Overall, refracturing treatment is more effective for fractured wells when initial fracture conductivity becomes lower. Reoriented/principal fracture length ratio has a weak negative correlation with the productivity index ratio, but reorientation fracture number shows a stronger influence on the stimulation than the other factors. Principal/reoriented fracture angle, fracture length ratio, reorientation fracture number and fracture conductivity should be optimized before refracturing to achieve the optimal productivity. Additionally, in a rectangular reservoir, the central refractured well obtains larger productivity than the eccentric refractured well, and hydraulic fractures deploying along the reservoir extension can slightly increase well productivity.

作为一种重要的增产技术，重复压裂通常用于提高致密油藏的油气采收率，特别是对于这些油藏中性能较差/损坏的压裂井。但目前对重复压裂的增产效果尚不明确。准确评价重复压裂处理对差/损压裂井产能影响对致密油藏快速高效开发具有重要意义。本研究建立了初始压裂井模型和再压裂井模型两个半解析模型，分别计算其产能指标，进行产能定量评价。生产力指数比率，一个新定义的参数，反映了两个生产力指数的特征，计算以评估再压裂增产效果。与两个经典案例的比较表明我们的解决方案与之前文献中的结果完全一致，并验证了我们的解决方案的可靠性和准确性。结果表明，与初始压裂井相比，随着主/改向裂隙角或旋转角的增加，再压裂井产能先快速上升后放缓，但在初始裂缝导流能力较低时可能会出现反比关系。同时，相同初始裂缝导流能力下的产能指数比曲线收敛为一束曲线，随着再定向裂缝导流能力的增强，先增加后减慢。总体，当初始裂缝导流能力降低时，再压裂处理对压裂井更有效。重新定向/主裂缝长度比与产能指数比呈弱负相关，但重新定向裂缝数量对增产的影响大于其他因素。重压前应优化主/重定向裂缝角、裂缝长度比、重定向裂缝数和裂缝导流能力，以达到最佳产能。此外，在矩形油藏中，中心重复压裂井比偏心重复压裂井获得更大的产能，并且沿油藏延伸部部署的水力压裂可以略微提高井产能。重新定向/主裂缝长度比与产能指数比呈弱负相关，但重新定向裂缝数量对增产的影响强于其他因素。重压前应优化主/重定向裂缝角、裂缝长度比、重定向裂缝数和裂缝导流能力，以达到最佳产能。此外，在矩形油藏中，中心重复压裂井比偏心重复压裂井获得更大的产能，并且沿油藏延伸部部署的水力压裂可以略微提高井产能。重新定向/主裂缝长度比与产能指数比呈弱负相关，但重新定向裂缝数量对增产的影响强于其他因素。重压前应优化主/重定向裂缝角、裂缝长度比、重定向裂缝数和裂缝导流能力，以达到最佳产能。此外，在矩形油藏中，中心重复压裂井比偏心重复压裂井获得更大的产能，并且沿油藏延伸部部署的水力压裂可以略微提高井产能。重新定向裂缝数量和裂缝导流能力应在重复压裂前进行优化，以达到最佳产能。此外，在矩形油藏中，中心重复压裂井比偏心重复压裂井获得更大的产能，并且沿油藏延伸部部署的水力压裂可以略微提高井产能。重新定向裂缝数量和裂缝导流能力应在重复压裂前进行优化，以达到最佳产能。此外，在矩形油藏中，中心重复压裂井比偏心重复压裂井获得更大的产能，并且沿油藏延伸部部署的水力压裂可以略微提高井产能。