Near the drill bit local buck short

Abstract

The invention provides a near-bit local pressure reduction short joint which sequentially comprises an upper connector, a spiral rising flow generator and a lower connector from top to down. A first torque transfer block is fixedly connected inside the upper connector, and a second torque transfer block is fixedly connected inside the lower connector. The spiral rising flow generator comprises a transmission mandrel, a rotary outer sleeve and spiral blades, wherein the upper end of the transmission mandrel penetrates through and is fixed to a first torque transfer through hole formed in the first torque transfer block, the lower end of the transmission mandrel penetrates through and is fixed to a second torque transfer through hole formed in the second torque transfer block. A spiral section is arranged in the middle of the transmission mandrel and is sleeved with the rotary outer sleeve, and a screwing hole is formed in the rotary outer sleeve. The spiral blades are arranged on the outer wall of the rotary outer sleeve. The near-bit local pressure reduction short joint effectively reduces well bottom pressure difference, reduces hold-down effect and rock breakage strength and improves well drilling speed. In addition, the near-bit local pressure reduction short joint is simple in structure, convenient to use, safe and reliable.

Description

technical field [0001] The invention relates to the field of oil and gas drilling, in particular to a local depressurization short near a drill bit. Background technique [0002] In order to prevent blowout, traditional drilling is overbalanced drilling, that is, the drilling fluid pressure is greater than the formation fluid pressure and less than the formation fracture pressure. In order to ensure wellbore stability and avoid complex accidents, the density of traditional drilling fluid should be higher than the collapse pressure and pore pressure, and lower than the fracture pressure, so as to ensure that the wellbore does not collapse, blow out or leak. As the well depth increases, the drilling speed gradually decreases. There are two main reasons for this: 1. Under the action of the bottom hole fluid column pressure and the formation pore fluid pressure difference, the cuttings generated by the drill bit breaking the rock are pressed in place. Repeated cutting by the dr...

AI Technical Summary

Problems solved by technology

In view of this conclusion, underbalanced drilling (also known as negative pressure drilling, which refers to the drilling technology in which the bottom hole pressure is lower than the formation pressure during drilling, and the fluid at the bottom enters the wellbore in a controlled manner and circulates to the surface) has been adopted in the prior art. The rate of penetration has been greatly increased, and the formation damage has been reduced. However, this technology is only applicable to some formations, and this technology requires high equipment capacity, large investment, and is prone to risks such as well collapse and wellbore expansion. The conditions for large-scale application immature

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