The RSS has been widely used in directional drilling. In order to enhance wellpath control accuracy and efficiency of the static push-the-bit RSS, a powerful BUR prediction method is reconstructed by coupling a rotary steerable bottom-hole assembly (RSBHA) mechanical model and a drill bit–rock interaction model. This article showed that when establishing the RSBHA mechanical model by using the continuous beam column method, the steering rib should be treated as an eccentric stabilizer to consider the contact effect between the steering rib and wellbore wall. For the beam column containing the flexible sub and between two stabilizers, it should be rearranged into three beam columns, and the lower and upper steps of the flexible sub should be considered as virtual supports. The equilibrium tendency method (ETM) to predict the BUR can enhance wellpath prediction accuracy than those of traditional methods. Under 3D conditions, the total drilling tendency angle should be denoted by inclination tendency angle and azimuth tendency angle to enhance the solution efficiency. Case analyses have verified that the average forecast error of the BUR prediction model in this article is less than 1°/30 m.

It is a promising measure to transmit downhole information by acoustic wave through drill string. However, the transmission distance and quality of acoustic signals in field conditions are still not satisfied because the acoustic frequency spectrum in drill string is vulnerable to interference. This paper studied acoustic frequency spectrum characteristics in periodic drill string by experiments under different axial tensile forces. The multilevel method is established to evaluate frequency spectrum through drill string based on improved radar chart. The impact of axial tensile force on spectrum characteristics is analyzed by the proposed method. The results indicate that the axial tensile force has remarkable impact on the acoustic frequency spectrum and passband characteristics. The spectrum characteristics change with axial tensile force. These changes are reflected in the position, width, and attenuation of different passbands. And the extent of changes is distinct to different passbands. Both the evaluation indicators of each passband and spectrum are change with increasing axial tensile force. The spectrum quality is excellent in the range of 17‐134 MPa for axial tensile force in drill string. And when the force exceeds 152 MPa, methods such as adjusting the carrier frequency and relay installation location are necessary to improve the transmission quality of acoustic signals.

It is a hot topic for deep/ultradeep wells to improve rock-breaking efficiency and drilling speed by available downhole energy. Based on different downhole energies and working conditions, specialized plunger pump is proposed to convert longitudinal vibration of drilling string into rock-breaking energy. Technical design is developed to generate high-pressure water jet. And then a simulation model is built to verify feasibility of the technical design. Through simulation, the influence law of key factors is obtained. On this basis, this device is tested in several wells. The result indicates this device can increase drilling speed as much as 136%. Meanwhile the harmful vibration can be absorbed. The energy from drilling string vibration is of high frequency and increases as well depth and formation anisotropy increase. By reducing adverse vibration, this device is able to increase the drilling speed and the service life also meets the demand of field application. The longest working time lasts for more than 130 hours. The performance of this device demonstrates great application prospect in deep/ultradeep resources exploration. To provide more equipment support for deep/ultradeep wells, more effort should be put into fundamental study on downhole drill string vibration and related equipment.