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we developed a novel approach for designing and fabricating depth-varied reservoir-on-a-chip micromodels using the silicon-based multi-depth fabrication strategy and on-chip random generation algorithm. Depth-varied reservoir-on-a-chip micromodels can mitigate confinement of uniform depth and maintain the wide range of pore size distribution similar to natural-occurring 3D porous media. The imbibition experiments performed in the single-depth and multi-depth reservoir-on-a-chip micromodels show the complex interaction between depth variation, capillary number Ca, and wettability (contact angle) θ on multiphase flow dynamics. The combination of micromodel experiments and direct numerical simulations enabled us to purify the complex capillarity as snap-off and by-pass phenomena. A theoretical model was proposed for suppressing or triggering these unstable imbibition phenomena. Phase diagrams predicted by the models were theoretically analyzed and numerically verified, they show that for θ≤45°, increasing Ca stabilizes the imbibition front by suppressing the snap-off mode; for contact angle θ&lt;90°, increasing θ stabilizes the imbibition front by inhibiting the by-pass mode, but increasing depth variation destabilizes the imbibition front as snap-off or by-pass or their combined effect. Our findings extend the classical understanding of forced imbibition in 2D micromodels. The results have potential applications in predicting or manipulating CO2 capillary trapping and enhanced gas/oil displacement efficiency.本研究采用硅基多深度制备策略与片上随机生成算法，开发了一种用于设计与制备深度可变型芯片储层微模型（depth-varied reservoir-on-a-chip micromodels）的全新方法。该深度可变型芯片储层微模型可缓解单一深度带来的局限，并能复刻天然三维多孔介质的宽孔径分布特征。针对单深度与多深度芯片储层微模型开展的自吸实验表明，深度差异、毛细管数（capillary number, Ca）与润湿性（wettability，其表征参数为接触角θ）之间的复杂交互作用，会对多相流动力学产生显著影响。通过结合微模型实验与直接数值模拟，本研究厘清了复杂毛细作用下的夹断（snap-off）与绕流（by-pass）现象。本研究提出了一种可调控上述非稳定自吸现象的理论模型，既能抑制也可触发这类现象。通过理论分析与数值验证，对模型预测得到的相图展开研究后发现：当接触角θ≤45°时，提升毛细管数Ca可通过抑制夹断模式来稳定自吸锋面；当接触角θ<90°时，增大接触角θ可通过抑制绕流模式来稳定自吸锋面，但提升深度差异则会通过夹断、绕流或二者共同作用，使自吸锋面失稳。本研究成果拓展了二维微模型中强制自吸现象的经典认知框架。该研究结果在预测或调控二氧化碳（CO₂）毛细封存以及提升油气驱替效率领域具备潜在应用价值。