非常规水平井多簇射孔与分段压裂联作管串泵入控制模型

The Control Model for Pumping Down Tool String Composed of Tussocky Perforation Guns and Frac Plug in Unconventional Horizontal Well

根据非常规水平井泵送式电缆多簇射孔与可钻桥塞分段压裂联作工艺特点,结合电缆注脂密封机理与油气井管柱力学理论,建立井口注脂密封压力控制模型、工具串结构参数控制模型及泵入排量控制模型。通过实例分析,研究工具串泵送下井过程中关键参数的控制方法,探讨井口压力、井身结构、电缆下放速度等对泵人控制参数的影响规律。随井口压力的增加,注脂泵排量需不断提高,以增大密封压力,工具串所需重量也不断增大;井身结构对工具串长度设计的影响比较大,随狗腿度的增加,允许通过工具串最大长度明显减小;泵入排量是电缆下放速度的一次关系式,应保持泵人排量与电缆下放速度的协调变化,防止井底电缆发生缠绕现象或因张力过大而发生泵脱事故。

According to technical characteristics of multistage fracturing technology using frac plugs in unconventional horizontal well, model governing seal pressure of grease injection is developed on seal mechanism of grease injection, while models governing structure parameters of tool string and pump rate are established on tubular mechanics in oil-gas wells. Through a case study, parameter control methods for pumping down tool string composed of tussocky perforation guns and frac plug efficiently are studied, and the effects of wellhead pressure, hole configuration, running velocity of wireline on control parameters are investigated. Results show that, increase of wellhead pressure requires an increase of grease injector to improve seal pressure, and hence an increase of weight to run tool string into the hole. The designed length of tool string is restricted by hole configuration, and with the increase of dog leg severity of well, the maximum allowable length decreases obviously. In addition, the coordination between running velocity of wireline and pump rate is important for preventing any accidents, such as the wireline winding around perforting guns or breaking at weak point.