Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs. However, the mechanisms and capacity are still unclear, which significantly limits the application of this technique. In order to figure out the mechanisms, the whole process of pressurizing, high-pressure soaking, and depressurizing was firstly discussed, and a mechanistic model was established. Subsequently, the simulation model was verified and employed to investigate the significances of high-pressure soaking, the contributions of different mechanisms, and the sensitivity analysis in different scenarios. The results show that high-pressure soaking plays an essential role in oil production by both imbibition and elasticity after hydraulic fracturing. The contribution of imbibition increases as the increase in bottom hole pressure (BHP), interfacial tension, and specific surface area, but slightly decreases as the oil viscosity increases. In addition, it first decreases and then slightly increases with the increase in matrix permeability. The optimal soaking time is linear with the increases of both oil viscosity and BHP and logarithmically declines with the increase in matrix permeability and specific surface area. Moreover, it shows a rising tendency as the interficial tension (IFT) increases. Overall, a general model was achieved to calculate the optimal soaking time.

为了在致密/页岩储油层中进行水力压裂后，进行了水吞吐以提高采油率。但是，机制和能力仍不清楚，这严重限制了该技术的应用。为了弄清楚机理，首先讨论了加压，高压浸泡和减压的全过程，并建立了机械模型。随后，对仿真模型进行了验证，并用于研究高压均热的意义，不同机理的贡献以及在不同情况下的敏感性分析。结果表明，高压浸泡在水力压裂后的吸油和弹性作用中都起着至关重要的作用。吸收作用随着井底压力（BHP），界面张力和比表面积的增加而增加，但随着油粘度的增加而略有下降。另外，随着基质渗透率的增加，它先降低然后略有增加。最佳浸泡时间与油粘度和BHP的增加呈线性关系，对数随基质渗透率和比表面积的增加而对数减少。此外，随着界面张力（IFT）的增加，它呈现出上升的趋势。总的来说，获得了一个通用模型来计算最佳浸泡时间。最佳浸泡时间与油粘度和BHP的增加呈线性关系，对数随基质渗透率和比表面积的增加而对数减少。此外，随着界面张力（IFT）的增加，它呈现出上升的趋势。总的来说，获得了一个通用模型来计算最佳浸泡时间。最佳浸泡时间与油粘度和BHP的增加呈线性关系，对数随基质渗透率和比表面积的增加而对数减少。此外，随着界面张力（IFT）的增加，它呈现出上升的趋势。总的来说，获得了一个通用模型来计算最佳浸泡时间。