Flexible short piece with rollers

Abstract

The invention discloses a flexible short piece with rollers and relates to the field of downhole tools in the petroleum industry. The flexible short piece comprises an upper joint, a spherical joint,a spherical bolt and a lower joint. The upper joint and the lower joint are both provided with multiple rollers, the rollers are uniformly distributed along the circumference at fixed angles, the lower portion of the upper joint is detachably connected with the spherical joint, the spherical joint is movably connected with the lower joint through a spherical bolt, so that the upper end of the lower joint can freely deflect in the range of 0-15 degrees along the spherical joint. The friction force between an instrument string and a tube wall can be effectively decreased, the rigid length of theinstrument string is effectively decreased, the swing amplitude at the instrument connecting positions is increased, the friction force with the tube wall is decreased, and the passing performance ofthe instrument string is obviously improved.

Description

technical field [0001] The invention relates to the field of testing fixtures for downhole tools in the petroleum industry, in particular to a roller flexible short joint. Background technique [0002] In the production process of shale gas wells, it is necessary to grasp the production dynamics to achieve efficient development. Putting the pressure gauge down to the end of the pipe string as much as possible is conducive to deepening the understanding of the dynamic and static characteristics of the reservoir, and accurately grasping the seepage characteristic parameters such as reservoir permeability and formation pressure. etc., to provide a basis for gas reservoir development. At the same time, as the production of gas wells enters the middle and later stages, formation pressure and gas production decrease, and formation water cannot be discharged in a timely and effective manner, resulting in fluid accumulation in the wellbore. If the fluid accumulation is severe, the ...

AI Technical Summary

Problems solved by technology

[0004] (1) Limited by the wellbore trajectory, the inclination angle of the build-up section changes greatly, and the azimuth of some wellbores also changes greatly. It is difficult for conventional tool strings to pass through the high-inclination section and the azimuth sudden change section

[0005] (2) At present, shale gas wells are mainly completed with 23 / 8" tubing. The small diameter of the tubing string limits the range of tool selection, and limits the counterweight and passable length of the tool string.

At the same time, large-scale sand fracturing is used for shale gas wells, and formation cuttings, large-diameter bridge plug fragments, and sand particles are returned to the wellbore after production, which easily leads to difficulties in lowering and extraction

[0007] In the prior art, centralizers are generally used to straighten the steel wire work to solve the above problems, but there are some defects in the existing centralizers, mainly including: 1. There are roller grooves on the body of a common roller centralizer, and there are roller grooves in the roller grooves. Rollers are installed, and the friction between the tool and the inner wall of the pipe string is reduced through the contact of the rollers with the inner wall of the pipe string. However, the diameter of the centralizing block cannot be changed, the centralization accuracy is not high, and the centralizer wears seriously during the centralization work; 2. There are also elastic centralizers, It is mainly designed based on the principle of springs. The springs are supported by the springs. The springs have a restoring force and play a role in righting. However, great axial frictional resistance will be generated during the lifting process. The supporting force is limited.

In addition, both centralizers have the disadvantages of long rigid length and insufficient passing performance

Images