通道压裂是低渗透致密油气藏高效、低成本开发的关键技术,通过采用非连续簇团铺砂的方式,使裂缝中形成具有高导流能力的通道,但目前关于通道压裂的理论研究仍然处于起步阶段.因此,基于计算流体力学建立欧拉-欧拉固液两相流模型,对通道压裂过程中支撑剂的分布状态进行模拟,通过与实验结果进行对比,证明了所建立模型的有效性,并系统研究了不同中顶压裂液(纯压裂液脉冲段)黏度、支撑剂密度、泵注排量对通道压裂通道率的影响.结果表明,中顶压裂液的黏度从1 mPa.s增加到20 mPa.s,通道内平均通道率增加5%;支撑剂密度从1400 kg/m3增加到2000 kg/m3时,缝内通道率减小了7%;排量由3 m3/min增加到7 m3/min时,通道率由28%增加到33.5%后减小到31%.现场应用过程中应使用较高黏度中顶压裂液、较低密度支撑剂和合理的泵注排量以保证裂缝中形成有效支撑通道.
Channel fracturing is a crucial technology for the efficient and economical development of low-permeability tight oil and gas reservoirs.High-conductivity channels can be formed in fractures through the technique of discontinuous cluster sand laying.However,theoretical research on channel fracturing is still nascent.Utilizing computational fluid dynamics,this paper establishes a Euler-Euler solid-liquid two-phase flow model to simulate proppant distribution during channel fracturing.The effectiveness of the model was validated by comparison with experimental results.The effects of varying mid-top fracturing fluid viscosity,proppant density,and pumping rates on channel fracturing efficiency were systematically investigated.As the mid-top fracturing viscosity of fluid increased from 1 mPa·s to 20 mPa·s,the average channel passage rate increased by 5%.An increase in proppant density from 1400 kg/m3 to 2000 kg/m3 resulted in a 7%decrease in the in-seam passage rate.As displacement increased from 3 m3/min to 7 m3/min,the channel rate rose from 28%to 33.5%,before decreasing to 31%.In practical applications,utilizing high-viscosity,low-density proppants,and an optimal pumping rate is recommended to ensure effective propping of channels in fractures.