Research progress and prospects of mechanical automatic vertical drilling technology for ultra-deep wells

Abstract:

As continental scientific drilling advances toward 10000-meter ultra-deep wells， the extreme downhole conditions of temperatures exceeding 300 ℃ and pressures over 175 MPa render electrically-controlled vertical drilling systems ineffective. Featuring a purely mechanical structure and a temperature resistance potential of up to 300 ℃， mechanical vertical drilling technology has become the core solution for deviation prevention and straight-hole drilling in ultra-high temperature deep wells. This paper systematically reviews the working principles and research progress of mechanical vertical drilling technology， comparatively analyzes the structural characteristics and field application performance of representative domestic and international products， and identifies significant gaps between China and foreign countries in deviation correction accuracy， temperature resistance， and engineering maturity. On this basis， three key technical issues are examined： the dynamic response of the mechanical stabilization platform under downhole vibrations， innovative push-the-bit actuators， particularly the bit fluid steering concept， and high-temperature materials and sealing. It is pointed out that existing rib-type push-the-bit systems suffer from the inherent limitation of formation-sensitive steering performance， rib wear， and the degradation of deviation correction accuracy caused by stick-slip vibration affecting the stabilization platform. Future research should focus on improving deviation correction accuracy， developing materials resistant to 300 ℃， investigating multi-field coupled dynamic mechanisms， and advancing domestic engineering applications， thereby promoting a transformative upgrade of the actuator from "rib-type pushing" to "bit fluid steering" and providing technical support for 10000-meter continental scientific drilling projects.