A new design of automatic vertical drilling tool

In order to effectively improve penetration rates and enhance wellbore quality for vertical wells, a new Automatic Vertical Drilling Tool (AVDT) based on Eccentric Braced Structure (EBS) is designed. Applying operating principle of rotary steering drilling, AVDT adds offset gravity block automatic induction inclination mechanism. When hole straightening happens, tools take essentric moment to be produced by gravity of offset gravity lock to control the bearing of guide force, so that well straightening is achieved. The normal tool's size of the AVDT is designed as 215.9 mm，other major components' sizes are worked out by the result of theoretical analysis, including the offset angle of EBS. This paper aims to introduce the structure, operating principle, theoretical analysis and describe the key components' parameters setting of the AVDT.