Intermittent downhole pressure drop nipple

Abstract

The invention discloses an intermittent sub-joint for lowering the bottom-hole pressure difference, which comprises an outer cylinder, a drill pipe joint, a spring and an annular piston. Rod joint, the drill pipe joint part is inserted into the shaft hole, and a water flow channel is arranged in the center of the drill pipe joint along its axial direction; the spring and the annular piston are both sleeved on the lower part of the drill pipe joint and can move up and down along its central axis, and the spring The upper end is connected to the drill pipe joint, and the lower end of the spring is connected to the upper end surface of the annular piston; a pressure relief hole and a reverse nozzle are set on the side wall of the outer cylinder, the pressure relief hole communicates with the chamber, and the upper end surface of the annular piston is subjected to external annular pressure. The lower end surface of the annular piston is subjected to the drilling fluid pressure in the shaft hole. When the annular piston moves up to a certain distance under the action of the pressure difference between the upper and lower end surfaces, the reverse nozzle communicates with the shaft hole. The invention can improve the effect of reducing the pressure difference at the bottom of the well, accelerate the drilling speed of the drilling machine, and enhance the ability of the drill bit nozzle to clean the bottom of the well and assist rock breaking.

Description

technical field [0001] The invention relates to a pressure-reducing and speed-increasing tool for oil and gas drilling, in particular to an intermittent sub-joint for reducing the pressure difference at the bottom of a well. Background technique [0002] The bottom hole pressure difference refers to the pressure difference between the hydrostatic column pressure in the well and the formation pore pressure, which is one of the important factors affecting the increase of drilling speed. Laboratory experiments and field practice show that the ROP will decrease significantly with the increase of the bottom hole pressure difference. Broken, affecting the rock-breaking efficiency of the drill bit. When drilling in low-permeability rock formations, the bottom hole pressure difference has a greater impact on drilling speed than in high-permeability rock formations, because it is difficult for drilling fluid to enter the pores of low-permeability rock formations and cannot be balanc...

AI Technical Summary

Problems solved by technology

Jet-type hydraulic decompression technology and negative pressure pulse jet decompression technology have not been popularized and applied due to their complex structure, high process requirements, and relatively harsh application conditions.

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