Static Push-the-Bit Rotary Steering Control Model and Build-up Rate Prediction Method

The push-the-bit rotary steerable tool (RST) has strong anti-inclination ability, which can basically meet the needs of safe and efficient drilling in complex formations. However, the current prediction method of build-up rates does not fully consider the influence of push-the-bit unit control and drilling process and has low prediction accuracy of build-up rates. Therefore, In view of the structural characteristics of the steering tool, a static push-the-bit rotary steerable control model was established, and a reliable steerable force control scheme was given. By using the bottom hole assembly (BHA) mechanics model and the bit-formation interaction model, a prediction model of build-up rates based on the zero lateral rate of penetration was obtained, and the conversion coefficient was introduced to correct the prediction result of build-up rates. The results of case calculation and sensitivity analysis show that the method has high prediction accuracy and can meet the need for precise control of borehole trajectory. The steerable force, weight on bit (WOB), and the distance between the bit and the stabilizer have significant effects on the deflecting ability of push-the-bit RST. In field construction, in order to give full play to the role of steerable force, it is necessary to shorten the distance between the bit and the stabilizer and reduce the WOB, so as to improve the deflecting ability of the RST. The research results can provide a theoretical basis for the optimization of rotary steerable BHAs and drilling parameters.