A clogged waxy crude oil pipeline, entails a high pressure to de-structure the gelled oil and resume its normal operation. Our earlier work, which utilized generalized Newtonian fluid based model, demonstrated that the presence of a gas pocket in-between the gel plugs, delays pressure propagation in the downstream gel plug [L. Tikariha, L. Kumar, Pressure propagation and flow restart in the multi-plug gelled pipeline, Journal of Fluid Mechanics. 911 (2021)]. This delay in pressure propagation is effectively utilized for sequential gel degradation. In the present work, we consider gel as a rheomalaxis elasto-viscoplastic (REVP) fluid, capable in predicting flow stoppage and pressure signal stoppage. The governing equations for mass, momentum balance, and phase equation are solved together with the REVP rheology model. The propagation of pressure in a REVP gel-filled pipeline is directly related to the gel material's elastic response. For a REVP gel, the flow-restart in a gelled pipeline depends on the conditional statement $\gamma >{\gamma }_s$ (i.e. mean gel deformation overcoming the yield strain). In the case of a single gel plug, no-pressure propagation is predicted at intermediate compressibility, whereas pressure propagation without flow restart is predicted at low compressibility. In these cases, the presence of a small gas pocket instigates the gel breakage process, resulting in a flow restart. The gas pocket delays the pressure propagation in the second gel plug, resulting in a pressure gradient higher than yield stress across the first gel plug. The first gel plug, which deforms under a high-pressure gradient, compresses the gas pocket. This results in a larger mean deformation in the first gel plug, and it overcomes the threshold yield strain limit $\left({\gamma }_s\right)$. At strain values larger than yield strain the gel structure breaks, resulting in a lower elastic strength in the first gel plug. The lower elastic gel strength ascertains a lower pressure gradient in the first gel plug, allowing a largely unattenuated pressure to propagate in the second plug. The propagation of unattenuated pressure in the second gel plug results in a pressure gradient higher than the yield stress. This causes sequential gel breakage, resulting in a successful flow restart in a pipeline longer than a critical length. The present study also demonstrates that the pressure propagation and initial transient flow depend on the gel properties (i.e. gel strength and compressibility) and the number and size of gas pockets in the gel. The insights gained from the present work provide a cost-effective solution to mitigate the flow restart problem.

堵塞的含蜡原油管道需要高压来破坏凝胶油的结构并恢复其正常运行。我们早期的工作利用基于广义牛顿流体的模型，证明凝胶塞之间存在气袋，延迟了下游凝胶塞中的压力传播 [L. Tikariha, L. Kumar，多塞凝胶管道中的压力传播和流动重新启动，流体力学杂志。911 (2021)]。这种压力传播的延迟被有效地用于顺序凝胶降解。在目前的工作中，我们将凝胶视为一种流变性弹性粘塑性 (REVP) 流体，能够预测流动停止和压力信号停止。质量、动量平衡和相方程的控制方程与 REVP 流变模型一起求解。REVP 凝胶填充管道中的压力传播与凝胶材料的弹性响应直接相关。对于 REVP 凝胶，凝胶管道中的流动重启取决于条件语句$\gamma >{\gamma }_{秒}$（即克服屈服应变的平均凝胶变形）。在单个凝胶塞的情况下，在中等压缩率下预测无压力传播，而在低压缩率下预测没有流动重新启动的压力传播。在这些情况下，小气袋的存在会引发凝胶破裂过程，导致流动重新启动。气袋延迟了第二个凝胶塞中的压力传播，导致压力梯度高于第一个凝胶塞上的屈服应力。第一个凝胶塞在高压梯度下变形，压缩气袋。这导致第一个凝胶塞的平均变形更大，并且它克服了阈值屈服应变极限$\left({\gamma }_{秒}\right)$. 在应变值大于屈服应变时，凝胶结构破裂，导致第一个凝胶塞的弹性强度降低。较低的弹性凝胶强度确定了第一个凝胶塞中较低的压力梯度，允许在第二个塞中传播很大程度上未衰减的压力。未衰减压力在第二个凝胶塞中的传播导致压力梯度高于屈服应力。这会导致连续的凝胶破裂，从而导致在超过临界长度的管道中成功重新启动流动。本研究还表明，压力传播和初始瞬态流动取决于凝胶特性（即凝胶强度和可压缩性）以及凝胶中气穴的数量和大小。