Downhole sand bailing tool

Abstract

The invention discloses a downhole sand bailing tool. The downhole sand bailing tool comprises an upper check valve, a plunger pump, a sand storage pipe, a lower check valve and a shovel head which are sequentially connected from top to bottom. The plunger pump comprises an outer cylinder and an inner plunger arranged in the outer cylinder, the inner plunger comprises a liquid draw pipe, a connector and a piston which are sequentially connected from top to bottom, and the outer cylinder comprises a positioning sleeve and an outer pipe which are sequentially connected from top to bottom. The outer wall of the piston is sleeved with a sealing ring and sealed on the inner wall of the outer pipe, and the bottom of the piston is connected with a plug used for adjusting the tightness of the sealing ring. The downhole sand bailing tool is simple in structure; a brand-new design thought is adopted from the perspective of oil reservoir protection, settling sand in a well can be bailed out simply by moving a pipe string up and down without using pump trucks or other auxiliary equipment, damage caused by working fluid to the stratum is avoided, and the oil reservoir can be effectively protected. Meanwhile, the tool is easy to operate, reliable in process, high in safety, low in cost and high in benefit, and can be applied to various complex well conditions such as vertical wells, horizontal wells and sidetracked wells.

Description

technical field [0001] The invention relates to an oilfield production pipe string, in particular to a downhole sand dredging tool. Background technique [0002] The development of the oil field is in the middle and later stages. Some blocks are affected by long-term water injection or gas injection production and the unreasonable production system of oil wells. The reservoir skeleton is damaged, resulting in sand production in the oil layer. The oil layer collapsed and the sand production was further aggravated. When the sand output of the oil well reaches the sand-buried production layer, it will cause the oil well to reduce or stop production. For the treatment of sand production in oil wells, the existing conventional sand cleaning methods in oil fields mainly include hydraulic sand washing and mechanical sand dredging. The hydraulic sand washing method has the characteristics of large amount of sand washing at one time, complete cleaning of the bottom of the well, and...

AI Technical Summary

Problems solved by technology

The hydraulic sand washing method has the characteristics of large amount of sand washing at one time, complete cleaning of the bottom of the well, and simple process, but the construction cost is high. When the formation pressure coefficient is low, a large amount of sand washing fluid will leak into the formation and pollute the oil layer; when the well is very deep When the formation pressure is low, it is difficult for the sand washing fluid to return to the ground, and the hydraulic sand washing method is ineffective, and sand stuck in the pipe string is prone to occur; To a certain extent, it will cause damage to the formation, which is not conducive to the next step of oil well development

Although the conventional mechanical sand removal does not require external sand washing fluid and will not pollute the oil layer, it has the disadvantages of less sand removal at one time, long tripping time when the well is deep, low sand removal efficiency, and uneconomical.

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