A deep-sea double-tube bottomhole three-channel pressure control system and control method

Abstract

The invention discloses a three-channel pressure control system and control method at the bottom of a deep-sea double-layer tube well, including double-layer tubes, casings, drill bits, conversion joints, outer sleeves, axial flow pumps, turbine motors, liquid level monitoring sensors, and valve groups Control unit, double-layer pipe return manifold, drilling fluid pumping manifold, drilling pump, drilling fluid circulation tank; the conversion joint is connected to the lower end of the double-layer pipe, and the outer sleeve is sleeved on the upper On the half part, the axial flow pump and the outer sleeve are respectively connected to the lower end and middle part of the conversion joint, the axial flow pump, the turbine motor, and the drill bit are connected in sequence, the double-layer pipe is placed in the casing, and the inner The pipe, outer pipe and casing are concentric strings. The double-layer pipe of the present invention forms three drilling fluid channels, and by changing the lifting performance of the axial flow pump, the self-adaptive control of the bottom hole pressure is realized, and the dynamic balance of the bottom drilling fluid column pressure is effectively maintained.

Description

technical field [0001] The invention relates to a deep-sea double-tube well bottom three-channel pressure control system and a control method, belonging to the technical field of deep-water oil and gas drilling engineering. Background technique [0002] The exploitation of oil and gas resources is developing in the direction of deep formations, low permeability, offshore oil and gas, and unconventional oil and gas. my country is actively expanding the deep water field in the South China Sea. However, deep sea drilling and development are facing many difficulties, the most prominent one being the problem of "narrow drilling safety density window". , due to the loose sediments of the deep seabed and the seawater column, the range of formation pressure and fracture pressure is very narrow. Drilling accidents such as leakage, overflow, well collapse and stuck pipe will occur if the drilling safety density window is exceeded. How to stabilize the bottom hole pressure within the s...

AI Technical Summary

Problems solved by technology

However, the injection volume of low-density fluid is not easy to control, and it is easy to cause slug flow, which makes the drilling fluid density control accuracy poor

The injection point and injection device of low-density medium have complex structures, poor reliability, and high economic costs

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