压裂液气举返排优化设计

Design optimization for hydraulic fracturing gas-lifting flowback

随着压裂施工井深不断增大,压裂液仅靠自喷的返排量已达不到设计要求,因此,需要选择下入气举阀进行气举返排的方式人工助排。为此,开展了气举返排优化设计研究,建立了平衡点深度计算模型,通过计算油管压力分布和环空压力分布,确定平衡点深度,继而进行气举排液参数优化设计。文中通过分析注气参数对平衡点深度以及排液速度的影响发现:平衡点位置主要受注气压力和井口压力影响,与二者呈线性相关性——注气压力每增加1.0 MPa,注气平衡点深度下移154 m左右,井口压力每增大0.1 MPa,注气点深度下移16 m左右;排液速度主要受注气速度影响,随井口压力的增大呈线性减小的趋势,注气压力和井口压力对排液速度的影响也不可忽略。

With the increasing fracturing depth, flowback rate of fracturing liquid without artificial equipments can′ t meet the requirement of construction site, so gas lift valve to help flowback is laid down. In order to solve this problem, a model to define the equilibrium point is established by calculating the pressure distribution of fracturing string and annulus, the optimized design for gas-lifting flowback parameters are obtained. Analyses of the effect of air injecting parameters on equilibrium point and delivery rate show that equilibrium point is mainly affected by air injecting pressure and wellhead pressure, which has a linear correlation：equilibrium point moves down about 154 m with air injecting pressure increases 1 MPa, equilibrium point moves down about 16 m while wellhead pressure increases 0.1 MPa; delivery rate is mainly affected by air injecting rate, along with the increase of wellhead pressure it decreases linearly, and the effect of wellhead pressure and air injecting pressure on delivery rate can′t be ignored.