A device and method for recovering drill string in an accident well

Abstract

The invention discloses a device and a method for recovering a drill string in an accident well. The device is mainly composed of an upper casing, a sealing ring, a mandrel, a spring, a lower casing and a pressure-holding ball. The body is respectively connected with the upper drill string and the lower drilling tool; the upper casing and the lower casing are connected by threads, the mandrel is connected with the upper casing and the lower casing by splines, and a spring is arranged between the mandrel and the lower casing, Sealing rings are arranged between the outer walls of the upper and lower ends of the mandrel and the inner walls of the upper casing and the lower casing. When the drill string cannot be taken out from the well, the pressure-holding ball is put into the drill string from the ground, and the pressure-holding ball moves along the inner annulus of the drill string until the inverted conical flow channel on the mandrel, and the mud pump is started to suppress the pressure-holding ball. Push the mandrel to move down, the spline of the mandrel will be disengaged from the upper keyway, the upper casing and the lower casing are connected with left-handed threads, when the drill string is rotated to the right, the upper casing and the lower casing will Separation, thereby allowing the upper casing and its upper drill string to be withdrawn from the wellbore.

Description

technical field [0001] The invention relates to a device and a method for recovering a drill string in an accident well, and belongs to the technical field of drilling such as oil and gas exploitation. Background technique [0002] Drilling is a necessary process for oil and gas production. It is characterized by the high-speed rotation of the drill string system driven by the ground rotary table, and the drill string acts on the rock through its own weight to continuously extend the wellbore. For the drill string, it has a large length-to-diameter ratio. During the drilling of deep wells, ultra-deep wells or hard formations, there are often cases of drill bit sticking. For example, in the development of some old wells, due to problems such as borehole bending and borehole diameter shrinkage, there is often a phenomenon that the drill string in the borehole cannot be taken out due to the sticking of the drill bit or the lower drilling tool. For the problem of drill bit or l...

AI Technical Summary

Problems solved by technology

These processes can solve most of the problems in the field related to bit or lower hole sticking, however, there are still situations where the sticking problem cannot be solved

In this case, rotating the drill string counterclockwise can remove some of the drill string, but one cannot control how much is removed

Under the action of this random factor, there is a possibility that a large number of drill strings will be scrapped together with the wellbore

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