高低黏度压裂液交替注入的组合流体压裂技术，兼顾缝高穿层和缝网复杂程度，是提高页岩油改造体积的有效调控手段。然而，目前关于压裂液黏度的研究多集中于破裂压力和裂缝形态的影响，对渗吸和水化效应的研究尚未充分展开。采用宏观与微观实验相结合的方法，系统对比了不同黏度滑溜水作用前后页岩的吸水量、裂缝发育、孔隙结构、矿物组成及力学性能的变化。实验结果表明，去离子水水化作用显著改变了页岩的物理性质，产生了明显的溶蚀孔及大量平行于层理面的水化裂缝，导致力学性能大幅度改变。相比之下，随着滑溜水黏度的增加，页岩水化效应逐渐减弱，表现为基质表面无明显溶蚀孔隙产生、原有裂缝宽度变化不显著以及未出现新的水化裂缝，力学参数的劣化程度低于去离子水。分析认为，去离子水由于较大的界面张力，易于渗入黏土矿物层间隙，促使黏土膨胀形成新的裂缝，并加速黄铁矿氧化和碳酸盐溶解，形成溶蚀孔隙以进一步促进水化。而滑溜水在页岩表面形成的聚丙烯酰胺涂层通过氢键和表面络合作用抑制了矿物溶解和孔隙生成。研究结果揭示了滑溜水黏度对页岩水化作用的影响机制，为现场的压裂液设计和优化提供了理论依据。

Combination fracturing technique with alternating injection of high-and low-viscosity fracturing fluids balances fracture height and fracture network complexity, making it an effective strategy for enhancing the stimulated reservoir volume (SRV) of shale oil reservoirs. However, existing research on fracturing fluid viscosity has primarily focused on fracture pressure and morphology, while the effects on imbibition and hydration have been insufficiently explored. This study combines macro-and micro-scale experiments to systematically compare changes in water absorption, fracture development, pore structure, mineral composition, and mechanical properties of shale before and after exposure to slickwater with varying viscosities. Results show that deionized water hydration significantly alters shale's physical properties, generating pronounced dissolution pores and a large number of hydration-induced fractures parallel to bedding planes, leading to a severe deterioration in mechanical properties. In contrast, as slickwater viscosity increases, the hydration effects weaken, evidenced by the absence of obvious dissolution pores, minimal changes in existing fracture widths, and no new hydration fractures. The degradation of mechanical parameters, such as elastic modulus, was less pronounced than with deionized water. The analysis suggests that the higher interfacial tension of deionized water facilitates its penetration into clay mineral interlayers, promoting clay swelling, inducing new fractures, and accelerating pyrite oxidation and carbonate dissolution, further enhancing hydration via the formation of dissolution pores. In contrast, the polyacrylamide coating formed by slickwater on the shale surface inhibits mineral dissolution and pore generation through hydrogen bonding and surface complexation. This result reveals the impact mechanism of slickwater viscosity on shale hydration and provides theoretical guidance for the design and optimization of fracturing fluids in the field.