Punching-shear composite drill bit for hard rock drilling

Abstract

The invention discloses a punching-shear composite drill bit for hard rock drilling. The punching-shear composite drill bit comprises three parts of an impactor, an internal punching bore bit and an external cutting drill bit, a lower joint of the impactor can be in threaded connection with the external cutting drill bit, and the upper part of the internal punching bore bit is connected with the impactor in a spline mode; and the lower end face of the internal punching bore bit extends out of the surface of the external cutting drill bit, the central axis of the internal punching bore bit is parallel to or coincident with the central axis of the external cutting drill bit, distributed teeth on the internal punching bore bit and distributed teeth on the external cutting drill bit are combined and can completely cover a downhole, and distributed teeth on the internal punching bore bit and the distributed teeth on the external cutting drill bit are independent of each other. In this way,rock crushing through shearing and rock crushing through impact are creatively combined together, a rock stratum at the hole bottom is pre-cracked first through the internal punching bore bit, the whole tectonic stress of the rock stratum is destroyed, the strength of compression resistance and shearing resistance of rock is reduced so that PDC column teeth and PDC cone teeth can more easily cut / plough-cut the rock, and the rock-breaking efficiency of the super hard rock stratum is greatly improved.

Description

technical field [0001] The invention relates to the technical field of drilling tools for exploration and development of petroleum gas, coal bed methane, etc., in particular to a punching-shear composite drill bit for hard rock drilling. Background technique [0002] The PDC bit breaks the rock through the compressive shearing effect of the cutting teeth on the rock in front of the blade, and makes full use of the low shear strength of the rock. The proportion of drilling in soft to medium hard formations is far higher than that of the roller cone bit. An important way to save drilling costs. However, as the demand for exploration and development of oil and gas and coalbed methane becomes stronger, more and more deep wells and ultra-deep wells are drilled, and the formation conditions encountered are becoming more and more complicated. Quartz sandstone, conglomerate, and chert are often drilled. For formations with high hardness, strong abrasiveness, and poor drillability, ...

AI Technical Summary

Problems solved by technology

When drilling, the drill bit is not only under the action of a certain axial pressure, but also driven by the drilling rig to rotate through the drill string, and at the same time bears a certain frequency of impact energy, while the impact toughness of the cutting teeth of the PDC bit is relatively limited. The cutting teeth are prone to chipping under the action of the impact rotary drilling process. Therefore, the DTH hammer drill bit used in the impact rotary drilling process is generally made of cemented carbide, and the wear resistance of cemented carbide is relatively poor, especially when the diameter of the drill is small. When it is large, the outer ring carbide teeth wear faster, resulting in limited service life

In addition, when the hole diameter is large, the large-diameter down-the-hole hammer used is powered by wind, and the drilling efficiency increases with the increase of air supply volume. At the same time, the required air volume for slag removal is also large, so it must be equipped with a multi-hole hammer with sufficient air supply volume. A single air compressor requires a large investment and high energy consumption, which directly affects the application of percussion rotary drilling technology

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