The roller cone bit is the most widely used type of drill bit. During operation, the cutting teeth of the roller cone bit alternate contact with the well bottom, resulting in a small rock-breaking torque and a small contact area between the cutting teeth and the well bottom, which generates high pressure and is easy to cut into the formation. The total length of the working edge is long, so relative wear is reduced. The roller cone bit can adapt to various formations from soft to hard.
Based on the number of teeth, the roller cone bit can be divided into single tooth, two teeth, three teeth, and four teeth roller cone bits. According to the cutting material, it can be divided into steel teeth (milling teeth) and inlaid teeth roller cone bits.
As a tool for drilling rock formations, the roller cone bit has been widely used. The significant improvement in drill bit performance directly reduces drilling costs, especially in the past decade. The performance indicators of service life and drilling speed ultimately determine the degree to which the drill bit affects the drilling cost. Improving the mechanical drilling speed and service life of the drill bit is an effective way to reduce drilling costs. Data have shown that improving drilling speed has a greater impact on reducing drilling costs than improving drill bit life, and improving the cutting structure of the drill bit is the most direct way to improve its mechanical drilling speed.
For a long time, the improvement of cutting structure has focused on the main cutting tooth structure. For example, in the field of hard alloy tooth structure, wedge-shaped teeth, spoon-shaped teeth, biased top spoon-shaped teeth, and equal wear teeth have been invented one after another. In the past decade, people have gradually realized that the gauge structure also has a significant impact on the mechanical drilling speed and service life of the drill bit, especially for drill bits used in highly inclined and horizontal wells. Drill bits with a reasonable gauge structure are required, and many new gauge structures have been developed and applied to roller cone bits with good results.
