Characteristics of Deflecting Drilling in Ultrashort-Radius Horizontal Wells
Ultrashort-radius horizontal well technology is an important way to reconstruct old wells,increase well production and improve flow potential,and has positive significance for the secondary development of maturing blocks of oilfields.On the basis of Drucker-Prager criteria,a 3D sandstone model was built to simulate the side-tracking build-up process of flexible drill string,study the force laws exhibited during sidetracking at different cur-vature radii,and clarify the deflecting drilling mechanism of flexible drill string in strata as well as the ultrashort-ra-dius angle building mechanism of flexible drill string.The results show that the borehole curvature of ultrashort-ra-dius horizontal well is the result of joint action of factors such as lateral force,axial force,sliding friction force,weight on bit(WOB)transfer and torque transfer on flexible drill string.The lateral force on the flexible drill string is negatively correlated with the radius of borehole curvature,and the larger the radius of borehole curvature,the more apparent the vibration frequency,and the greater the WOB consumption is.The axial force is directly propor-tional to the radius of borehole curvature,and the smaller the borehole curvature,the smaller the impact of friction and collision on the torque loss is.In the drilling of ultrashort-radius horizontal well,it is necessary to properly ad-just the WOB,increase the rotation speed,increase the displacement and pumping pressure,and improve the well-bore cleaning efficiency,thereby improving the deflecting efficiency and drilling speed of flexible drill string.The study results provide theoretical support for the field application of ultrashort-radius horizontal well drilling technolo-gy and the development of remaining oil and unconventional oil and gas.
万方数据
维普
