纤维支撑剂团静态沉降速度计算方法

水力压裂过程中,脉冲注入含纤维的支撑剂团可以有效保持其在裂缝输送沉降过程中的完整性,从而形成柱状支撑裂缝。通过实验再现了纤维支撑剂团静态沉降过程中的完整性,将压裂液-纤维-支撑剂三相混合物处理为单相流体,通过修正液相的流变性获得混合物的物性,考虑纤维支撑剂团在静态沉降过程中所受的重力、浮力、壁面摩擦力和绕流阻力,建立其沉降速度计算公式及数值计算迭代算法。对比实验中纤维支撑剂团沉降速度发现,所建模型预测结果与实验结果符合度较高。通过支撑剂密度、支撑剂体积分数、纤维支撑剂团直径和裂缝宽度等因素对纤维支撑剂团沉降速度的影响发现:随着支撑剂密度、支撑剂体积分数和裂缝宽度的增大,纤维支撑剂团沉降速度随之增大;纤维支撑剂团直径对其沉降速度影响较小。

Calculation model of static settling velocity of fiber-containing proppant clumps

During hydraulic fracturing,the pulsed injection of fiber-containing proppant clumps effectively preserves their integrity during fracture transport and settling,resulting in columnar propped fractures.Through our experiment,the integri?ty of fiber-containing proppant clumps was shown.The fracturing fluid-fiber-proppant mixture was treated as a singlephase fluid.The physical property of the mixture was obtained via corrected rheological property.The gravity,buoyancy,wall friction and flow resistance of fiber-containing proppant clumps in static settling were considered to establish the for?mula of settling velocity and its substitute algorithm for numerical calculation.By comparing the settling velocities of the fi?ber-containing proppant clumps,we found that the predicted results of the model were in good agreement with the experi?mental results.The settling velocities affected by proppant density,proppant volume fraction,clump diameter and fracture width were further calculated.As a result,the settling velocity rises with the increase in proppant density,proppant volume fraction and fracture width.However,it is little influenced by clump diameter.This model provides an effective method to calculate the static settling velocity of fiber-containing proppant clumps and a theoretical basis for the calculation of their transport.