DRILL BIT PROVIDING COMBINED EFFECT OF INDUCED LOAD AND ABRASIVE JET AND WELL DRILLING METHOD

摘要

Disclosed is a drill bit providing a combined effect of an induced load and an abrasive jet. The drill bit utilizes an outer annular drill bit (2) for pilot bore rock breaking, utilizes a center drill bit (3) mounted at the middle of the annular drill bit (2) and arranged within the drill bit for crushing a center rock pillar (4), thus inducing the unloading of well-bottom stress, utilizes rock debris produced from rock breaking by the center drill bit (3) as an abrasive and a well-drilling liquid (5) flowing into the interior of the entire drill bit as an abrasive jet liquid phase, thus producing an abrasive jet (503), and utilizes the combined effect of the induced unloading and the abrasive jet to increase the rock breaking efficiency of the drill bit. Also disclosed is a well drilling method using the drill bit: a well drilling and rock breaking process is divided into two parts, first, a donut-shaped wellbore is produced by crushing, then, the rock pillar inside the donut-shaped wellbore is crushed, thus effectively inducing the unloading of the well-bottom stress, the rock debris produced by breaking the rock pillar inside the donut-shaped wellbore is utilized as an abrasive and is mixed with the well-drilling liquid entering the drill bit to form the abrasive jet (503), and the combined effect of the induced unloading and the abrasive jet is utilized to achieve the goal of increasing well drilling and rock breaking efficiency.