带封隔器的油套合压管柱油管临界排量计算

为防止油套合压过程中封隔器因承受较大活塞力而发生移位，开展了保证封隔器不发生移位的油管临界排量计算研究。通过管柱受力分析，建立了压裂管柱轴向力计算模型，利用有限元分析软件模拟了封隔器胶筒的锚定力。根据压裂管柱所受轴向力与锚定力的关系建立了保证封隔器不发生移位的油管临界注入排量计算模型。通过计算得出:当地层破裂压力梯度为2.1 MPa/100m时，井深2 000.00 m处φ60.3，φ73.0及φ88.9 mm油管的临界排量分别为0.965，0.810和0.470 m3/min；而在井深3 000.00 m处，3种尺寸油管的临界排量分别为1.120，0.985和0.680 m3/min；临界排量随井深增加而增大，随油管尺寸增大而减小；在选取的地层破裂压力梯度范围内，地层破裂压力梯度为1.8 MPa/100m时，φ88.9 mm油管的临界排量最小，为0.46 m3/min。研究结果表明，油管排量大于临界排量可有效防止封隔器发生移位，有助于确保油套合压过程中压裂层位和压裂深度的准确性。 

Calculation of Tubing Critical Pump Rate while Fricturing by both Tubing and Casing with Packers

In order to prevent packers from moving in tubing and casing fracturing due to great piston force,the study on critical tubing pump rate which won’t cause packer motion was conducted.Through mechanical analysis of string,the calculation model of axial force for fracturing string was established,the anchoal force of packer rubber was simulated by using finite element software.So the calculation model of tubing critical pump rate which won’t cause packer motion was established according to the relationship of axial force and anchor force.The calculation results showed that critical pump rate of φ60.3 m,φ73.0 mm and φ88.9 mm tubings is 0.965 m3/min,0.810 m3/min and 0.470 m3/min respectively at well depth of 2 000 m and the fracturing pressure gradient of 2.1 MPa/100m,but at the depth of 3 000 m,the critical pump rate is 1.120 m3/min,0.985 m3/min and 0.680 m3/min respectively,which shows that the critical pump rate increases with well depth,and decreases with the increase of tubing size.Furthermore,when formation fracturing pressure gradient is 1.8 MPa/100m,the critical pump rate of φ88.9 mm tubing was the minimum value of 0.460 m3/min.It is concluded that only tubing injection pump rate higher than the critical value can the fracturing string be prevented from moving effectively, which is beneficial for insuring the accuracy of fractured interval and depth in the operation of tubing and casing fracturing.