Double-wall screw drilling system based on gas-liquid two-phase drive

Abstract

A dual-wall screw well drilling system based on gas-liquid two-phase drive comprises a ground system, a well opening device and a downhole drilling tool assembly. The ground system comprises a gas storage and collection tank and a liquid storage and collection tank, wherein the gas storage and collection tank and the liquid storage and collection tank communicate with the well opening device through an air compressor and a liquid high-pressure pump correspondingly and then are connected with a gas-liquid two-phase flow recovery device. The gas-liquid two-phase flow recovery device comprises asand recover, a back-pressure valve and a ground gas-liquid separation device. The downhole drilling tool assembly comprises a dual arm drilling rod I connected with the well opening device. The lowerportion of the dual arm drilling rod I is sequentially connected with a short joint, a dual-wall screw motor, a universal joint, a downhole gas-liquid separation device I, a dual arm drill rod II anda drill bit. According to the dual-wall screw well drilling system, the problem that an air screw is prone to being damaged under a well can be reduced, the rock breaking efficiency can be improved,and therefore safe, rapid and economical well drilling can be achieved on a horizontal well and a directional well.

Description

technical field [0001] The invention belongs to the technical field of underbalanced drilling, and in particular relates to a double-wall screw drilling system based on gas-liquid two-phase drive. Background technique [0002] In oil drilling engineering, underbalanced drilling has become an important aspect of the efficient development of oil and gas fields because it can well protect oil and gas reservoirs, increase the rate of penetration, significantly shorten the drilling cycle, prevent well leakage and collapse accidents, reduce drilling costs, and liberate oil and gas layers. means. [0003] Gas drilling or air foam drilling formed by gas combined with recyclable foam are two important drilling methods for underbalanced drilling. At present, these two drilling methods are mainly used for vertical well drilling. For directional wells or horizontal wells, there are only The air screw is applied on site for the gas drilling of the drilling tool. However, the air screw d...

AI Technical Summary

Problems solved by technology

[0004] (1) When the pure air screw drilling tool is in use, the rotor rotates at a high speed, and the screw rotor and the air rub against each other to generate heat, resulting in damage to the sheath of the motor's flexible helical flap cavity, which affects the drilling speed

[0005] (2) During the drilling process of pure air screw drilling tools, when the drilling pressure increases, the pressure difference between the inlet and outlet of the motor increases, the air volume at the motor inlet decreases, and the output speed also decreases accordingly. Excessive drilling pressure will cause motor failure. Stall or braking; at the same time, because air will leak from the high-pressure primary seal cavity to the low-pressure primary seal cavity, knocking will occur, resulting in uneven speed

When the drill bit is lifted from the bottom of the well, the torque decreases, the pressure difference between the inlet and outlet of the motor decreases, and the air volume suddenly increases, resulting in a sudden increase in the motor speed, causing a "speeding" problem, which affects the normal rock-breaking drilling of the drill bit

[0006] (3) During the normal drilling process of the pure air screw drilling tool, the air flow is insufficient, resulting in insufficient power and poor power durability, and the torque provided to the drill bit is small, resulting in a slowdown of the drill bit's drilling speed

[0007] (4) The ground equipment of pure air screw drilling tools is expensive

[0008] It can be seen from the above that there is no effective method to realize safe, fast and economical drilling tools for the formation when using air screw drilling tools for drilling operations.

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