Inland and offshore oil exploitation, large displacement, and horizontal well are more and more widely used, which can significantly improve the oilfield exploitation efficiency and economic benefits. However, in the complex drilling process, the debris particles generated in the large displacement and horizontal well section drilling are deposited in the lower low-speed area of the lower part of the ring empty shaft. It will cause underground accidents such as complex moving, drilling, increased resistance, drilling column fracture, and so on, which will seriously affect the efficiency and economic benefits of drilling. This paper addresses the problem of annular debris accumulation and the characteristics of high-density drilling fluid and uses the CFD-DEM (discrete cell method) method to simulate the debris movement process in the well eye based on the coupling of FLUENT and EDEM software. The edge calculation is used to provide strong resource allocation and calculation force support for this paper, fully consider the influence of the interaction between drilling fluid, debris particles, and drilling rod and well wall, and explore the influence law of the eccentric ring space of the conventional steel drill pipe.