Abstract: To address the challenges of wellbore instability, drilling fluid loss, and water scarcity in the shallow soft formations of the Shaanxi-Inner Mongolia region, this study aims to develop a high-performance micro-foam drilling fluid system to enhance drilling efficiency. By comparing the foaming capacity and stability of three foaming agents, AE Plus was selected as the optimal core foaming agent. Subsequently, an orthogonal experimental design was employed to systematically optimize the concentrations of the foam stabilizer, fluid loss reducer, and plugging agent, leading to the determination of the optimal formulation. Laboratory evaluation results indicate that after aging at 110 ℃ for 16 hours, the optimized system maintained excellent rheological properties and sealing capacity, with an apparent viscosity of 28 mPa·s, a yield point of 15 Pa, and an API filter loss of 8.2 mL. Field tests further confirmed that, compared to conventional drilling fluids, this micro-foam system successfully prevented fluid loss and pipe sticking, increased the rate of penetration by 26.3% in the same interval, and achieved a comprehensive water saving rate of 63.1%. It is concluded that through the synergistic effect of the micro-foam's "bridging" plugging mechanism and the polymers, this system effectively resolves the issues of wellbore stabilization and loss prevention in soft formations, providing reliable technical support for safe and efficient coalbed drilling in water-scarce areas.