Combined drill bit combining PDC drill bit and roller bit for joint rock breaking

Abstract

The invention discloses a combined drill bit combining a PDC drill bit and a roller bit for joint rock breaking. The combined drill bit combining the PDC drill bit and the roller bit for the joint rock breaking is characterized in that the combined drill bit comprises the PDC drill bit and the roller bit which are connected to each other; the PDC drill bit comprises a round steel body, a plurality of blade sets and a plurality of grooves are milled in the side face of the round steel body, each blade set comprises a first blade and a second blade, and each first blade and the corresponding second blade are line-shaped connection blades; the roller bit comprises a plurality of bit legs arranged in the grooves, bit cone sets are arranged on the lower portions of the bit legs, and the bit cone sets correspond to the blade sets one to one; each bit cone set comprises a first bit cone and a second bit cone, and bit cone conical face breaking faces and bit cone circular-arc breaking faces are formed on the outer sides of the first bit cones and the outer sides of the second bit cones respectively; a roller bit oil storage sealing bearing system and a hydraulic jet system are arranged on the round steel body. The combined drill bit combining the PDC drill bit and the roller bit for the joint rock breaking improves drill bit rock breaking efficiency, and the service life of the drill bit is ensured; furthermore, the performance measure of well drilling is good, and the cost of the well drilling is lowered.

Description

technical field [0001] The invention belongs to the field of drill bits for petroleum geology drilling, and in particular relates to a combination drill bit in which a PDC drill bit and a roller cone bit are combined to break rock. Background technique [0002] In the prior art, when the drilling encounters a hard formation, the commonly used PDC bit mainly realizes downhole drilling through scraping movement, and the main cutting elements on the nose and shoulder of the diamond bit are difficult to effectively penetrate into the rock at the bottom of the well , the mechanical penetration rate of the diamond drill bit will become very slow; while the roller cone bit breaks the rock by impact crushing, which is easy to produce deep crushing tooth pits in the rock, but due to the hard formation, the rock cannot be broken in volume, so the tooth The cutting efficiency of the cutting teeth of the roller bit is also very low, and the ROP of the roller bit is also very slow. On t...

AI Technical Summary

Problems solved by technology

[0002] In the prior art, when the drilling encounters a hard formation, the commonly used PDC bit mainly realizes downhole drilling through scraping movement, and the main cutting elements on the nose and shoulder of the diamond bit are difficult to effectively penetrate into the rock at the bottom of the well , the mechanical penetration rate of the diamond drill bit will become very slow; while the roller cone bit breaks the rock by impact crushing, which is easy to produce deep crushing tooth pits in the rock, but due to the hard formation, the rock cannot be broken in volume, so the tooth The cutting efficiency of the cutting teeth of the roller bit is also very low, and the drilling speed of the roller bit is also very slow

On the other hand, when the drill bit encounters some formations with more soft and hard interlayers, the cutting elements of the PDC bit are easily damaged by impact. In order to deal with this situation, Chinese patent document CN200880016630. The hybrid drill bit is a combination of drill bits. Although the hybrid drill bit has strong comprehensive performance, it has the following disadvantages: due to the rock-breaking mechanism of the three-cone bit, the impact load generated by the rotation of the cone is easy to cause the diamond bit to break. Part of the cutting element PDC composite sheet is broken, which leads to a decrease in the drilling speed of the drill bit. At the same time, the rock breaking efficiency of the above-mentioned combined drill bit is low, and the service life of the drill bit is short. At the same time, the existing drill bit increases the drilling cost, which is not convenient for the above-mentioned combined drill bit. Promotion

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