A compound eccentric single-cone bit

Abstract

The invention discloses a composite eccentric single-cone drill bit, which belongs to the technical field of drilling equipment such as petroleum and natural gas, mining engineering, building foundation engineering construction, geology, hydrology, etc., and includes a drill bit body, a cone, and a fixed cutting structure in front of the cone. The cone cutting teeth are arranged on the cone, the fixed cutting teeth are arranged on the fixed cutting structure in front of the cone, the drill body is provided with a journal, and the cone forms a rotational connection with the journal, so The front fixed cutting structure of the cone is fixedly connected to the front end of the journal, and the axis of the journal is offset by S from the axis of the drill bit. The value range of S is 0<|S|≤d / 3, and d is Drill outer diameter. The purpose of the present invention is to provide a compound eccentric single cone drill bit, which can improve the hydraulic condition of the drill bit and increase the service life of the drill bit while improving the rock-breaking efficiency of the drill bit.

Description

technical field [0001] The invention belongs to the technical field of drilling equipment such as petroleum and natural gas, mining engineering, building foundation engineering construction, geology, hydrology, etc., and specifically relates to a composite eccentric single cone bit. Background technique [0002] The drill bit is a rock-breaking tool used in drilling engineering to break rock and form a wellbore. The drill bits used in drilling engineering today mainly include roller cone bits and PDC (polycrystalline diamond compact) bits. [0003] The cone on the roller cone bit forms a rotational connection with the bit body through the bearing system. When the drill bit is working, the rotation of the bit body drives the cone to rotate around the axis of the drill bit. At the same time, the cone will also rotate around its own axis. The cutting teeth on the cone Under the synthesis of the above two kinds of motion, complex compound motion is performed, and the roller con...

AI Technical Summary

Problems solved by technology

The lack of wear resistance of the cutting teeth is the Achilles heel of the single-cone bit, and the easy wear of the cutting teeth seriously affects the service life of the single-cone bit

When the single cone bit is working at the bottom of the well, the teeth on the cone wear unevenly, and the cutting teeth in the constant contact area (the front end of the cone) wear faster and most severely, which reduces the mechanical penetration rate of the bit and accelerates the failure of the bit , resulting in reduced drill life

[0007] In addition, the water eye nozzle of the single cone bit is generally higher, and the water eye hole is added on the bit body of the upper part of the cone, or on the tip of the cone, because the lower half of the cone is completely attached to the bottom of the well (for the full hole) Drill bit), the hydraulic flow ejected from the water hole of the drill bit is difficult to clean the lower part of the cone below the water hole and the bottom of the well

When the single-cone bit is working, the hydraulic force between the lower part of the cone and the bottom of the well is insufficient, and the cuttings produced by the cutting teeth breaking the rock cannot be taken away in time, which is not conducive to the cleaning of the cutting teeth and the bottom of the well, and the cutting teeth cannot be fully cooled.

The debris trapped between the cone and the bottom of the well affects the drilling speed of the drill bit and also affects the cooling of the cutting teeth, which intensifies the temperature rise and wear of the cutting teeth

The bottom hole hydraulic defect of the single cone drill bit has always been one of the main problems that drill bit researchers have paid attention to, but it has not been well resolved.

This fixed-tooth PDC bit mainly has three disadvantages: first, the PDC teeth cut rocks continuously, and the heat generated by severe friction will cause the teeth to reach a relatively high temperature. When the temperature exceeds a certain limit, the PDC teeth will wear faster. A significant increase, which leads to the occurrence of thermal wear (when the PDC tooth working temperature is higher than a certain temperature, the phenomenon that its wear resistance decreases significantly is called the thermal wear phenomenon of the PDC tooth).

Second, the failure of individual teeth on the drill bit (tooth shedding, breakage or excessive wear, etc.) will significantly increase the working load of the PDC teeth near the bottom hole annular zone of the failed tooth, accelerate its wear rate, and lead to premature failure of the drill bit

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