复杂裂缝内支撑剂输送的关键参数及算法

发布时间：2019-03-31 12:38

【摘要】：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.
[Abstract]:Proppant transportation in complex fractures is one of the key problems which need to be improved urgently in fracturing site. By increasing the filling efficiency of proppant in branch fractures, the oil and gas stimulation effect can be significantly improved. At present, proppant transport in complex cracks is still in the stage of laboratory experimental exploration, and few mature theoretical studies have been reported. This paper summarizes the latest research progress at home and abroad, puts forward that the flow rate of fracturing fluid and the conditions of proppant steering are two key parameters of complex fracture sand-carrying, and abstracts the complex fracture system into a unitized physical model. The flow distribution and steering conditions were studied respectively. Based on the calculation method and modeling idea of the split flow rate of fracturing fluid in the limited flow fracturing, the split flow rate algorithm and the improved algorithm in the complex fracture element model are established respectively. The simulation and comparative verification of the split flow rate are carried out by using Fluent. The results show that the split flow rate of fracturing fluid in the complex fracture element model is simulated and verified by comparison. The relative error between the improved algorithm and the Fluent simulation results is-2.76%, and the calculated results are accurate. The critical flow rate starting from the surface proppant of the sand embankment is proposed to characterize the critical condition of the transfer of the proppant to the branch joint, and the algorithm of the critical turning condition is given. The calculated results of the algorithm are compared with the experimental results of Colorado School of Mines, and the experimental results are compared and analyzed. The average error is 8.18%, which indicates that the proposed algorithm can predict the critical velocity of proppant turning well. Based on the split flow rate of fracturing fluid and proppant steering condition algorithm, under the experimental condition of Katherine Thomas Technology Center, the transport of proppant with different particle sizes in the branch seam is predicted. The results are in agreement with the experimental results, and the experimental results are in good agreement with the experimental results. This provides a theoretical and methodological basis for improving proppant transport in complex fractures.
【作者单位】：中国石化石油工程技术研究院;中国石油大学(北京)石油工程学院;页岩油气富集机理与有效开发国家重点实验室;中国石化华东油气分公司勘探开发研究院;
【基金】：国家自然科学基金重大项目(51490653,U1562212,51521063)资助
【分类号】：TE357.12

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