Long-service-life drill bit suitable for difficult-to-drill stratums

Abstract

The invention discloses a long-service-life drill bit suitable for difficult-to-drill stratums. The drill bit comprises a drill bit body and a plurality of blades extending from the drill bit body, wherein water holes or nozzles are arranged in runners among the blades, each blade is provided with a plurality of first cutting teeth, the tooth arranging face of each blade is provided with sockets for fixing the first cutting teeth, and the contour lines of at least two blades have both non-overlap areas and overlap points or areas. By the structure, the drill bit can work in an asynchronous cutting manner, the longitudinal abrasion length of the drill bit can be increased, the service life of the drill bit can be prolonged, the drill bit can be allowed to be in a high-specific-pressure drilling state during the whole drilling process, the rock drilling ability of the drill bit is enhanced, the drilling speed of the drill bit in the difficult-to-drill stratums is increased, and the service life of the drill bit in the difficult-to-drill stratums is prolonged.

Description

technical field [0001] The invention belongs to the technical equipment fields of petroleum and natural gas drilling engineering, mining engineering, building foundation engineering construction, geological drilling, tunnel engineering, hydrology, shield tunneling and non-excavation, and in particular relates to a drilling bit. Background technique [0002] PDC bit is one of the main bit varieties used in drilling engineering (especially oil and gas drilling engineering). Relying on high-hardness, wear-resistant, self-sharpening polycrystalline diamond composite sheets to shear and break rocks, PDC bits are widely used in drilling engineering due to their high mechanical penetration rate, long life and low drilling cost in soft to medium hard formations. widely used. [0003] Existing fixed cutter bits represented by PDC bits usually have several blades, and multiple cutting elements are arranged on the blades along the radial direction of the bit (for PDC bits, the cutting...

AI Technical Summary

Problems solved by technology

However, the longitudinal backup teeth in the above two schemes are all internal inserts, and the main cutting teeth work according to the principle of synchronous cutting. The internal inserts as an auxiliary cutting structure must be used after the main cutting teeth are completely worn out and the body is partially worn. However, while the internal inserts are cutting rocks, the body of the blades has been in contact with the formation in a large area, which significantly reduces the specific pressure of the reserve cutters acting on the rocks, thus greatly limiting the drilling efficiency of the drill bit

[0009] The existing PDC bit with synchronous cutting principle is not only limited in drilling efficiency but also has a short service life when facing complex and difficult-to-drill formations (high hardness, high abrasiveness, even heterogeneous formations containing gravel layers, interlayers, etc.). ideal

The main reasons are as follows: First, in order to ensure that the drill bit has a strong ability to eat or penetrate the rock surface when drilling in hard formations, it is necessary to use cutting teeth with a small size (diameter), but the small diameter cutting teeth The exposed height is small, and the wearable height is significantly lower than that of the large-diameter cutter, but the wear speed of the cutter is faster at this time, thus forming an insoluble contradiction in the design of the drill bit for difficult-drilling formations: if the large-diameter cutter is used , the cutting teeth are difficult to penetrate into the rock (especially after a certain degree of wear), and the rock breaking efficiency of the drill bit is low; if the small diameter cutting teeth are used, the working life of the cutting teeth is not enough

Second, when the drill bit drills in hard formations and heterogeneous formations, the cutting teeth are often subjected to strong impact loads, and a small number or even individual cutting teeth are prone to rapid failure phenomena such as shedding, fracture, fragmentation, and cracking of the diamond layer. Once this phenomenon occurs, it will lead to the chain failure of the cutting teeth in the adjacent area due to the increase of the working load, and then the circumcision phenomenon, that is, the exposed part of the cutting teeth of the drill bit in the radial area is completely or mostly worn off. , and then grind out annular grooves on each blade body of the drill bit

Therefore, when the ring groove is worn out on the drill bit, it is generally considered that the drill bit has lost or is close to losing its cutting ability. Not only can it not be used in the well, but even repair (replacement or refurbishment of the worn cutting teeth) is difficult to implement in severe cases.

Images