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复杂裂缝内的支撑剂输送是压裂现场急需改善的关键问题之一,通过提高支撑剂在分支缝内的充填效率,能够显著提高油气增产效果.目前,复杂裂缝内的支撑剂输送研究还处于室内实验探索阶段,鲜有成熟的理论研究报道.本文总结了国内外最新研究进展,提出压裂液分流量和支撑剂转向条件是复杂裂缝携砂的两个关键参数,并将复杂裂缝系统抽象成单元化物理模型,分别开展了分流量和转向条件研究.借鉴限流压裂中压裂液分流量的计算方法和建模思路,分别建立了复杂裂缝单元模型中的压裂液分流量算法和改进算法,采用Fluent进行了分流量模拟和对比验证,结果表明,改进的算法与Fluent模拟结果相对误差为-2.76%,计算结果较准确.提出由砂堤表层支撑剂起动的临界流速表征支撑剂向分支缝转向输送的临界条件,并给出了临界转向条件的算法,将算法的计算结果与Colorado School of Mines的实验结果进行对比分析,平均误差为8.18%,表明该算法能够较好地预测支撑剂转向临界流速.综合压裂液分流量和支撑剂转向条件算法,在Katherine Thomas Technology Center的实验条件下,预测了不同粒径支撑剂在分支缝内的输送情况,结果与实验结论一致,从而为改善复杂裂缝内的支撑剂输送提供了理论和方法依据.
Proppant transport in complex fractures is one of the key issues urgently needed to be improved on the fracturing site, which can significantly increase the production efficiency of oil and gas by increasing the filling efficiency of proppant in the branch joints.At present, the proppant transport in complex fractures is still in the There are few mature theoretical research reports in the laboratory exploration stage.This paper summarizes the latest research progress both at home and abroad, and points out that fracturing fluid flow rate and proppant steering conditions are two key parameters for complex fracture sand-carrying and abstract the complex fracture system Into the unitized physical model, respectively, the diversion and steering conditions were studied.Considering the calculation methods and modeling ideas of the fracturing fluid flow in the limited-flow fracturing, the fracturing fluid flow distribution algorithm And the improved algorithm, the Fluent was used to simulate and verify the simulation results of shunt flow.The results show that the relative error between the improved algorithm and the Fluent simulation is -2.76%, and the calculation result is more accurate.It is proposed that the critical velocity character of the proppant Agent to the branch seam steering transfer critical conditions, and gives the critical steering conditions of the algorithm, the calculation results with the Colorad o School of Mines, the average error is 8.18%, which shows that the algorithm can predict the critical flow velocity of proppant well.According to the fracturing fluid split and proppant steering conditions algorithm, the Katherine Thomas Technology Center Under the experimental conditions, the transport of proppant with different particle sizes in the branch joints was predicted. The results are in good agreement with the experimental results, which provides a theoretical and method basis for improving proppant transport in complex fractures.