A Disc Cutter Composite Drill Bit Suitable for Difficult-Drilling Formation

Abstract

The invention discloses a disc cutter type multiple drill bit suitable for a hard-to-drill stratum. The disc cutter type multiple drill bit comprises a drill bit body, a plurality of cutter wings extending to the drill bit body, a disc cutter rotatably connected relatively to the drill bit body, and a water hole or a nozzle formed in the drill bit body; a plurality of first groups of cutting teeth are formed in the cutter wings, a slot is formed in the tooth surface of the cutter wing to fix the first group of cutting teeth, the disc cutter comprises a disc cutter body and disc cutter teeth arranged on the disc cutter body, the contour line of a body of at least one cutter wing and the contour line of a body of at least another cutter wing have at least one mismatched area in the common coverage area and at least one matched point or matched area. The structural feature enables the drill bit to work in an asynchronous cutting manner, so that the longitudinal abrasion length of the drill bit is increased, the service life of the drill bit is prolonged, in addition, the drill bit is kept in a high specific pressure drilling state in the whole drilling process, and the capability of the drill bit drilling in a rock is strengthened. Therefore, and the drilling speed and the service life of the drill bit in the hard-to-drill stratum are increased and 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] Drill bits are rock-breaking tools used to break rocks and form wellbores in drilling engineering. PDC bits and roller cone bits are commonly used. PDC bits rely on high hardness, wear-resistant, self-sharpening polycrystalline diamond composite sheets to shear and break rocks. PDC bits have high mechanical penetration rate, long life and low drilling cost in soft to medium hard formations. are widely used in. 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 elements are...

AI Technical Summary

Problems solved by technology

[0009] Existing PDC drills with synchronous cutting principle (including PDC drills with disc cutters) not only drill into complex and difficult-to-drill formations (high hardness, high abrasiveness, even gravel-containing layers, interlayers and other heterogeneous formations). Efficiency is limited and its working life is not 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.

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