页岩气水平井全井筒临界携液流量模型

目前的临界携液流量模型均未完整反映页岩气井的复杂井身结构和返排液量变化特征，无法准确预测页岩气水平井积液。为此，通过对液滴动力学和能量分析，综合考虑井筒产液量、液滴变形和造斜率变化引起的液滴能量损失，建立了页岩气井全井筒临界携液流量模型。根据最大稳定变形液滴能量平衡关系，确定了最大稳定变形液滴长轴长度；选取了适用于页岩气水平井的曳力系数和表面张力公式；根据误差分析优选了Mukherjee-Brill两相流模型计算页岩气水平井井筒压力分布。实例分析表明，与现有临界携液流量模型相比，新模型对于页岩气水平井的积液预测符合率最高，预测精度达92.3%。新模型可以准确预测积液井和接近积液井，对不积液井的积液预测精度也能满足现场应用要求，可以有效指导页岩气井积液判断与排采工艺选择。

Full-hole critical liquid carrying flow model of shale-gas horizontal well

None of current critical liquid carrying flow rate models can completely reflect the complex casing programs of shale gas wells and the change characteristics of flowback rate or accurately predict the liquid loading in shale-gas horizontal wells. In this paper, a full-hole critical liquid carrying flow rate model of shale gas well was established by analyzing droplet dynamics and energy and comprehensively considering the droplet energy loss caused by the liquid production rate, droplet deformation and build-up rate change in the wellbore. The long axial length of the droplet with maximum stable deformation was determined according to the energy balance relationship of the droplet with the maximum stable deformation. The drag coefficient and surface tension formula applicable to shale-gas horizontal wells were selected. Based on the error analysis, Mukherjee-Brill two-phase flow model was adopted to calculate the distribution of wellbore pressure in shale-gas horizontal well. The case analysis shows that compared with existing critical liquid carrying flow rate models, the new model is higher in the prediction coincidence rate of liquid loading in shale-gas horizontal well and its prediction accuracy is high up to 92.3%. The new model can accurately predict liquid loading wells and approximate liquid loading wells and its liquid loading prediction accuracy for the wells without liquid loading can meet the requirement of field application, so it can provide an effective guidance for judging liquid loading in shale-gas horizontal wells and selecting proper production technologies.