Vibration prediction method of completion pipe string of high-temperature, high-pressure and high-gas-rate well

Abstract

The invention belongs to the technical field of oil and gas exploitation, and particularly relates to a vibration prediction method of a completion pipe string of a high-temperature, high-pressure andhigh-gas-rate well. The vibration prediction method comprises the following steps: A, establishing a vertical and horizontal coupling dynamic model of the pipe string by using the horizontal right direction as an x axis and the well vertical depth direction as a y axis, and obtaining a pipe string total kinetic energy T calculation formula and a pipe string total potential energy U calculation formula; B, deducing the calculation formulae of the longitudinal vibration differential equation f(x,t) and the horizontal vibration differential equation p(x,t) of the pipe string; C, solving the longitudinal vibration differential equation and the horizontal vibration differential equation of the pipe string; and D, analyzing the longitudinal vibration displacement and the horizontal vibration displacement of the pipe string, the axial stress, the effective load and the bending moment of the pipe string according to the calculation results. The vibration prediction method provided by the invention can obtain the stress condition of pipe strings with arbitrary unit lengths in the completion pipe string, and theoretical support is provided for design, construction and maintenance of the completion pipe string of the high-temperature, high-pressure and high-gas-rate well.

Description

technical field [0001] The invention belongs to the technical field of oil and gas exploitation, and in particular relates to a vibration prediction method for a high-temperature, high-pressure, high-yield gas well completion pipe string. Background technique [0002] High-temperature, high-pressure, high-yield wells usually refer to wells with wellhead pressure greater than 70MPa (or bottomhole pressure greater than 105MPa), bottomhole temperature higher than 150°C, and production greater than 120×104m3 / d. Compared with conventional gas wells, high-temperature, high-pressure and high-yield wells have the following characteristics: high temperature will heat the completion fluid in the annular space, resulting in a passive increase in annular pressure, and the passively increased annular pressure will easily cause casing rupture; The risk of collapsing increases. On the other hand, it will lead to high pressure on wellhead opening and closing. Excessive well depth will cause...

AI Technical Summary

Problems solved by technology

Compared with conventional gas wells, high-temperature, high-pressure and high-yield wells have the following characteristics: high temperature will heat the completion fluid in the annular space, resulting in a passive increase in annular pressure, and the passively increased annular pressure will easily cause casing rupture; The risk of collapsing increases. On the other hand, it will lead to high pressure on wellhead opening and closing. Excessive well depth will cause the force and deformation of the completion string to affect the temperature, pressure, fluid density, viscous friction, tubing and well. The sensitivity of factors such as Coulomb friction between the walls increases, that is, the deformation caused by the temperature effect, swelling effect and piston effect of the pipe string has a prominent impact on the safety of the pipe string; high-production fluids easily cause low-frequency vibration of the curved pipe string , Non-periodic severe vibration, aggravated wear, leading to premature failure of the tubing string, forcing downhole operations, and even scrapping the wellbore, resulting in difficult and high-risk completion operations for high-temperature, high-pressure, high-production wells

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