A pdc bit suitable for tight mudstone formations

Abstract

The invention belongs to the field of drilling equipment, and in particular relates to a PDC drill bit suitable for tight mudstone formations, comprising an outer cutting unit; an inner cutting unit; a connecting rod; a locking mechanism and a diamond composite cutting tooth. It moves in the circumferential direction, and realizes the locking and release between the two cutting units through the locking mechanism. When cutting the fluffy formation, the inner cutting unit acts as a pilot bit and protrudes in front of the outer cutting unit, and the outer cutting unit acts as a reaming bit. The area around the inner cutting unit is reamed to improve the overall drilling capacity of the drill bit. At this time, there is a large gap between the inner blade and the outer blade, which can avoid the mud bag at the front end of the bit; when cutting tight mudstone formations, The inner cutting unit and the outer cutting unit can be kept flush, thereby dispersing cutting stress, ensuring stable drilling process and avoiding chipping. The invention can switch back and forth between the two working stations, so as to adapt to the complex formation environment where the soft and hard are interlaced.

Description

technical field [0001] The invention belongs to the field of drilling equipment, in particular to a PDC drill bit suitable for tight mudstone formations. Background technique [0002] PDC drill bits are also called polycrystalline diamond composite drill bits, which generally include a drill bit body and a polycrystalline diamond composite sheet embedded in the end of the drill bit body. Coated cutting parts. Traditional PDC bits are generally of one-piece structure, and the relative positions of the cutters are generally fixed. However, in actual use, it is found that for different geological layers, the cutting efficiency of the bit is greatly affected by the distribution of cutters. In the upper rock strata, using a smaller cutting area can significantly increase the drilling speed, while using a larger cutting area will lead to a decrease in the drilling speed and easy occurrence of mud bags at the end of the drill bit; while for tight mudstone strata, using a relativel...

AI Technical Summary

Problems solved by technology

Traditional PDC drill bits are generally of one-piece structure, and the relative positions of the cutting teeth are generally fixed. However, in actual use, it is found that for different geological layers, the cutting efficiency of the drill bit is greatly affected by the distribution of the cutting teeth. For example, in relatively fluffy In the upper layer of the rock, the smaller cutting area can significantly increase the drilling speed, and the larger cutting area will lead to the decrease of the drilling speed and the occurrence of mud balls at the end of the bit; and for the tight mudstone formation, using a larger The large cutting area is more beneficial to the stable feed of the drill bit

Since the drill bits in the prior art are all one-piece structures, it is necessary to replace the drill bits repeatedly when facing different rock formations, which seriously affects the drilling efficiency

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