Abstract
This study focuses on the transportation of non-uniform cuttings in the drilling process of long-reach horizontal wells, conducting a comprehensive theoretical analysis and experimental investigation. Initially, a computational model was established to analyze the influence of cuttings size distribution, fluid dynamics parameters, and wellbore geometry on the transport of non-uniform cuttings. The research elucidates the non-linear relationship between cuttings transport efficiency and parameters such as flow velocity, well inclination, and drill pipe rotation rate in long-reach horizontal wells. It also identifies the existence of a critical flow velocity, beyond which drilling fluid can effectively carry cuttings, preventing their accumulation at the well bottom, and ensuring wellbore cleanliness. Additionally, the paper proposes optimization strategies for wellbore cleaning based on the transport behavior of cuttings, including adjustments to fluid flow velocity and optimization of well inclination, aimed at enhancing drilling efficiency and reducing drilling costs. The findings provide theoretical guidance for cuttings management in long-reach horizontal wells, contributing to improved safety and cost-effectiveness in drilling operations. They hold significant value for advancing the technology of drilling horizontal wells under complex geological conditions.