Research on Dynamic Cuttings Transport in the Annulus of Large‐Offset 3D Horizontal Wells

ABSTRACT In the drilling process of large‐offset three‐dimensional (3D) horizontal wells, the issue of cuttings transport is a critical concern for wellbore cleanliness and downhole safety. Significant accumulation of cuttings can lead to various downhole accidents, such as excessive torque and drag, stuck pipe, and well control failure. To investigate the transport behavior of annular cuttings in large offset 3D horizontal wells, this study establishes a dynamic cuttings transport model based on the theory of annular solid–liquid two‐phase flow. The model reveals the effects of the rate of penetration (ROP) and hydraulic parameters on the transport behavior of annular cuttings and clarifies the distribution characteristics of cuttings under normal drilling and back reaming conditions throughout the wellbore. The results indicate that the transport behavior of cuttings differs among the vertical section, hold section, high build‐up rate section, and horizontal section of large‐offset 3D horizontal wells, with the stabilized cuttings bed thickness exhibiting the following relationship: high build‐up rate section > horizontal section > hold section > vertical section. Moreover, the accumulation of cuttings in large‐offset 3D horizontal wells is significantly greater than that in conventional two‐dimensional (2D) horizontal wells. During the drilling process in long horizontal sections, a higher ROP exacerbates cuttings transport issues. Compared to drilling without back reaming, the accumulation of cuttings can be reduced by approximately 50% after back reaming each pipe. The combination of optimized hydraulic parameters with drilling and back reaming is recommended to enhance wellbore cleanliness.