支撑剂沉降规律对页岩气压裂水平井产能的影响

压裂工艺后支撑剂的分布及裂缝形态对页岩气井的产能有很大影响。为了研究支撑剂沉降规律，建立了综合考虑页岩气吸附解吸附及应力敏感的气藏数值模型，并在模型中提出了表征支撑剂沉降的方法。通过对比分析不同射孔位置、不同沉降程度、裂缝导流能力、储层基质渗透率等参数变量，考虑了支撑剂沉降的页岩气藏压力分布和产能特征，得出影响支撑剂沉降后气井产能的主控因素。结果表明，支撑剂沉降大幅度降低了气井产能；考虑压裂过程中支撑剂运移沉降，应在油气藏中下部进行射孔；页岩气藏裂缝导流能力达到4 μm2·cm即可满足气井的有效开采，选用40/70目支撑剂进行压裂施工，建议优先造主缝；基质渗透率越高，支撑剂沉降对气井产能影响越大，高渗带要采取防止支撑剂沉降的措施。此模型考虑了支撑剂沉降的特性，对页岩气井产能的预测和现场压裂施工具有重要指导意义。

Effect of proppant settlement laws on the productivity of shale-gas horizontal wells after the fracturing

The productivity of shale gas wells is greatly in fluenced by proppant distribution and fracture morphology after the fracturing. To investigate the proppant settlement laws, the numerical reservoir model considering adsorption, desorption and pressure sensitivity of shale gas comprehensively was established. In this model, the method characterizing proppant settlement is developed.Then, parametric variables were compared and analyzed, e.g. perforation location, settlement degree, fracture conductivity, reservoir matrix permeability. The pressure distribution and productivity characteristics of shale gas reservoirs were studied in consideration of proppant settlement. And the main factors controlling the productivity of gas wells after proppant settlement were fi gured out. It is indicated that the productivity of gas wells is decreased greatly by proppant settlement. Considering the migration and settlement of proppant in the process of fracturing, perforation shall be carried out in the middle and lower parts of gas reservoirs. If the fracture conductivity of shale gas reservoirs is up to 4 μm2·cm, gas wells can be exploited effectively. The proppant of 40/70 mesh is selected for fracturing. It is recommended to create the main fractures preferentially. The productivity of gas wells is in fluenced more by proppant settlement as the matrix permeability is higher, so some measures shall be taken in high-permeability zones to prevent proppant settlement. This model takes into consideration the characteristics of proppant settlement, so it can be used as the important guide for the productivity prediction and on-site fracturing of shale gas wells.