Limit-level disconnection type double helix well bottom sand fluid mixing tubular column

Abstract

The invention provides a limit-level disconnection type double helix well bottom sand fluid mixing tubular column. The limit-level disconnection type double helix well bottom sand fluid mixing tubular column comprises a first-level oil tube and an n-level oil tube which are sequentially connected from the well opening to the well bottom. A plurality of double helix short sections and oil tubes are arranged between the first-level oil tube and the n-level oil tube. The double helix short sections and the oil tubes are alternately connected. The lower end of the n-level oil tube is sequentially connected with an upper double helix short section and an upper hydraulic ejector. The lower end of the upper hydraulic ejector is sequentially connected with a lower double helix short section and a lower hydraulic ejector. The lower end of the lower hydraulic ejector is connected with a retractable compensator. The lower end of the retractable compensator is connected with a bottom seal dragging fracture packer. According to the limit-level disconnection type double helix well bottom sand fluid mixing tubular column, a large amount of sand-carrying fluid at a high flow speed moves in a helix rotational flow state along a helix flow way, the effective sand concentration of the large amount of sand-carrying fluid flowing at the high speed is guaranteed, the stable state of the sand concentration of the sand-carrying fluid entering the upper ejector and the lower ejector of a multi-level clustering perforation is kept, and the perforating effect is improved.

Description

technical field [0001] The invention relates to a finite-stage discontinuous double-helix well bottom sand-fluid mixing pipe string, which is mainly suitable for volume fracturing of horizontal wells in multi-stage cluster perforation fracturing pipe strings. Background technique [0002] Horizontal well volumetric fracturing technology is currently the mainstream stimulation technology for increasing reserves and production in Changqing Oilfield. The key tool string for implementing this technology is multi-stage dragging / multi-stage immobile string hydraulic jet fracturing string. Due to the high pump Under the fluid flow of high pressure, large displacement, large liquid volume, and large sand volume, the sand-carrying liquid is prone to sand-liquid separation and granular sand deposition in the long horizontal section, which reduces the sand concentration and sand concentration at the upstream and downstream injectors. If the quantity is too large, the perforation effect...

AI Technical Summary

Problems solved by technology

The experiment found that when the high-speed sand-carrying liquid flows through a section of straight pipe, the granular sand moves from the bottom of the pipeline to the center of the pipeline, and more and more granular sand gathers towards the center of the pipeline and moves along the direction of the liquid flow in the pipeline , the distribution law of sand concentration along the height of the pipeline is "high at the center of the pipeline, low at the upper and lower walls of the pipeline", but when flowing through the double-helix diverter nipple, the high-speed sand-carrying liquid is rapidly mixed in a swirl state and The high-speed sand-carrying fluid still moves forward in a spiral swirling state after passing through the double-helix splitter nipple, and the movement displacement is relatively long

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