A scraping-impact compound drill bit

Abstract

Disclosed is a combination scraping and impacting drill bit, belonging to the field of rock-breaking tools for drilling equipment for petroleum and natural gas, mine engineering, fundamental architectural engineering construction, geology, hydrology, etc. The drill bit comprises a drill bit body (1) and a fixed cutting structure (2) consolidated onto the drill bit body (1); further the drill bit body (1) is provided with an impact cutting structure (3); the impact cutting structure (3) comprises a transmission mechanism (32) for transmitting the impact force, and impact cutting teeth (31); the impact cutting tooth (31) is consolidated onto a punch (321) at the end of the transmission mechanism (32); and the punch (321) can slide or slidingly impact relative to the drill bit body (1) in the direction of impact force transmission. By comparison with a traditional PDC drill bit, the present drill bit is not only favourable for the cutting tooth of the drill bit entering into earth strata such that the rock-breaking efficiency is improved, but also favourable for the wear rate of the cutting tooth to be reduced, and particularly the present drill bit has an obvious technical advantage in the conditions of hard earth strata with relatively high strength and comparatively strong grindability.

Description

technical field [0001] The invention belongs to the field of rock-breaking tools used for drilling equipment such as petroleum and natural gas, mining engineering, building foundation engineering construction, geology, and hydrology. Background technique [0002] The drill bit is a rock-breaking tool used in drilling engineering to break rock and form a wellbore. Conventional drill bits used in drilling engineering today mainly include three-cone drill bits, polycrystalline diamond compact drill bits (ie, PDC drill bits) and punching drill bits (also known as rotary punching bits or drill bits). [0003] The tri-cone bit mainly breaks rock in the form of crushing (the teeth press into the rock to break the rock). It is applicable to a wide range of formations, but the energy utilization rate is not high, and the rock breaking efficiency is relatively low. Especially when drilling in deep formations, under the action of high-density drilling fluid, the cuttings holding effec...

AI Technical Summary

Problems solved by technology

[0003] The tri-cone bit mainly breaks rocks in the form of crushing (the teeth are pressed into the rock to cause the rock to break), which is applicable to a wide range of formations, but the energy utilization rate is not high, and the rock breaking efficiency is relatively low.

Especially when drilling in deep formations, under the action of high-density drilling fluid, the cuttings holding effect at the bottom of the well is very obvious. It is difficult for the teeth to press into the formation and form effective fragmentation, and the mechanical penetration rate of the drill bit is greatly limited.

Low bearing life is one of the main factors restricting the service life of tricone bits

The tri-cone bit requires a large drilling pressure to ensure a high rock-breaking efficiency, so the load amplitude of the bearing is high. At the same time, the working principle of the teeth on the cone alternately breaking the rock will inevitably lead to axial or longitudinal vibration of the bit, and a relatively large amplitude. bearing load fluctuations

The main disadvantages of the PDC bit are: first, when the strength or hardness of the rock is high, it is difficult for the PDC teeth to eat into the rock to form effective scraping, especially when the PDC teeth are worn out, it is even more difficult for the teeth to enter the formation. The drilling speed of the drill bit will decrease sharply

Third, the wear rate of the PDC teeth on different radial areas of the PDC bit is significantly different. Generally, the wear rate of the cutting teeth in the outer area of ​​the drill bit (especially the outer 1 / 3 area of ​​​​the drill bit radius) is significantly faster than that of the teeth in the center area. Poor tooth wear balance, which reduces the overall performance of the drill bit

However, the drill bit also has the following obvious disadvantages: First, the axial (axial direction of the drill bit) or longitudinal overall movement of the roller cone cutting structure and the fixed cutting structure are consistent

Therefore, the inevitable up and down vibration of the gear cutting structure during the working process will directly affect the working stability of the PDC fixed cutting structure, resulting in two adverse consequences: First, the impact load brought by the longitudinal vibration is likely to cause the PDC teeth to be damaged. damage and shorten the service life of the drill bit; secondly, longitudinal vibration will cause frequent changes in the penetration depth of the PDC teeth in the fixed cutting structure. Rock breaking efficiency

Second, the cone is connected to the palm journal through the bearing system. Due to the need for strength, the geometric size of the cutting structure of the cone is relatively large, which occupies precious and limited space on the drill bit, which is not conducive to fixing the cutting structure on the drill body. and layout design of hydraulic structures

The large size requirement of the cone cutting structure also limits the application of this bit in deep slim hole drilling to a certain extent

Third, the working life of the bearing of the cone cutting structure has formed an obvious restriction on the overall life of the drill bit

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