Methods to improve MWD measurement reliability in ultra-deep horizontal slim-holes

The oil reservoir depth of the Shunbei oil and gas field is 7 300~8 600 m, associated with bottomhole temperatures of 160 ℃~210 ℃, and failure of the drilling steering device occurs frequently. At high temperatures, the factors affecting the measurement of an MWD device mainly include the device factor (mud pulse and MWD probe) and external factors of the operating environment (vibration, operation, corrosion, etc.). The latter can be improved or mitigated via proper measures. To improve the measurement reliability and trajectory control time-efficiency of the tool, this research investigated the effects of various factors on the device signal quality, such as vibration, thermal tolerance, operation and service environment, and developed specific technical measures. The research and field application shows the measurement reliability of MWD at high temperatures can be improved via proper technical measures by optimizing the mud motor drill dimensions, well trajectory, pulse generator time interval and mud circulation rate. This effectively reduces the device failure rate in ultra-deep directional/horizontal wells and enhances the well trajectory control performance of ultra-deep horizontal wells. The application of the presented technology to wells (e.g. SHB1-4HCH) delivers excellent performance, which validates the practicability of the proposed measures and provides valuable references for operations in analogous areas.