柔性钻具组合载荷传递过程中的力学行为研究OA

Ultra-short radius horizontal well technology plays a crucial role in enhancing the recovery efficiency of individual wells in mature oil fields.Flexible drilling tools constitute the core components of ultra-short radius horizontal well drilling systems.A flexible drill assembly can be characterized as a nested multi-flexible body system housed within the drill pipe.This study addresses the rotational constraints associated with semi-hinged structures,the geometric nonlinearity due to structural discontinuities and incomplete groove configurations,as well as the double-layer contact problem involving three-body interactions.A nonlinear mechanical analysis model and corresponding numerical method are developed to address the double-layer contact mechanics in horizontal drilling operations involving the flexible drill assembly.A mechanical analysis was conducted on a flexible drill assembly configured for a horizontal section extending 15 meters.Results indicate that during the horizontal drilling process,the torque loss rate of the flexible drill pipe is approximately 0.6％,while the axial force loss rate of the guide pipe reaches 18.8％.In the inclined section,the guide pipe is almost fully in contact with the wellbore wall,demonstrating favorable inclination control performance.The flexible drill pipe as a whole exhibits a distinct"sawtooth-shaped"deformation pattern,whereas the guide pipe remains relatively stable in terms of overall deformation.Both components display a downward movement trajectory;however,the lower section of the guide pipe shows a noticeable upward warping tendency.These findings provide theoretical support for the structural design optimization of flexible drill assemblies and enable the prediction of their movement trajectories during horizontal drilling operations.