After hydraulic fracturing treatment, a reduction in permeability caused by the invasion of fracturing fluids is an inevitable problem, which is called water blocking damage. Therefore, it is important to mitigate and eliminate water blocking damage to improve the flow capacities of formation fluids and flowback rates of the fracturing fluid. However, the steady-state core flow method cannot quickly and accurately evaluate the effects of chemical agents in enhancing the fluid flow capacities in tight reservoirs. This paper introduces a time-saving and accurate method, pressure transmission test (PTT), which can quickly and quantitatively evaluate the liquid flow capacities and gas-drive flowback rates of a new nanoemulsion. Furthermore, scanning electron microscopy (SEM) was used to analyze the damage mechanism of different fluids and the adsorption of chemical agents on the rock surface. Parallel core flow experiments were used to evaluate the effects of the nanoemulsion on enhancing flowback rates in heterogeneous tight reservoirs. Experimental results show that the water blocking damage mechanisms differ in matrices and fractures. The main channels for gas channeling are fractures in cracked cores and pores in non-cracked cores. Cracked cores suffer less damage from water blocking than non-cracked cores, but have a lower potential to reduce water saturation. The PTT and SEM results show that the permeability reduction in tight sandstones caused by invasion of external fluids can be list as guar gum fracturing fluid > slickwater > brine. Parallel core flow experiments show that for low-permeability heterogenous sandstone reservoirs with a certain permeability ratio, the nanoemulsion can not only reduce reverse gas channeling degree, but also increase the flowback rate of the fracturing fluid. The nanoemulsion system provides a new solution to mitigate and eliminate water blocking damage caused by fracturing fluids in tight sandstone gas reservoirs.

在水力压裂处理之后，由压裂液的侵入引起的渗透率的降低是不可避免的问题，称为水封破坏。因此，重要的是减轻和消除阻水损害，以提高地层流体的流量和压裂液的回流率。但是，稳态岩心流动方法不能快速，准确地评估化学剂在提高致密油藏流体流动能力方面的作用。本文介绍了一种省时，准确的方法，即压力传递测试（PTT），该方法可以快速，定量地评估新型纳米乳液的液体流量和气体驱动回流率。此外，扫描电子显微镜（SEM）用于分析不同流体的破坏机理以及化学剂在岩石表面的吸附。平行岩心流动实验用于评估纳米乳液对提高非均质致密油藏中返排率的影响。实验结果表明，阻水破坏机理在基质和裂缝中有所不同。气体通道的主要通道是破裂的岩心中的裂缝和未破裂的岩心中的孔隙。与未破裂的岩心相比，破裂的岩心受水堵的损害较小，但降低水饱和度的潜力较低。PTT和SEM结果表明，由外部流体侵入引起的致密砂岩渗透率降低可列为瓜尔胶压裂液>滑水>盐水。并行岩心流动实验表明，对于具有一定渗透率的低渗透非均质砂岩油藏，纳米乳液不仅可以降低反向气窜程度，而且可以提高压裂液的返排率。纳米乳液系统提供了一种新的解决方案，以减轻和消除由致密砂岩气藏中的压裂液引起的阻水损害。