Preset downhole filter and water filtering method

Abstract

The invention discloses a preset downhole filter and a water filtering method. The filter comprises a working barrel. A slotted screen part is arranged at the lower portion of the working barrel. Thebottom of the slotted screen part is sealed. A first filter element assembly is arranged at the lower portion of an inner cavity of the working barrel. An inner cavity of the first filter element assembly can communicate with the slotted screen part. A second filter element assembly is arranged at the upper portion of the inner cavity of the working barrel. An overflowing connector is arranged onthe lower side of the second filter element assembly. A core pipe is arranged in an inner cavity of the second filter element assembly. An inner cavity of the core pipe forms a fluid channel for injecting water flow into the first filter element assembly. The outer diameter of the core pipe is smaller than the inner diameter of the first filter element assembly. The preset downhole filter furthercomprises a ball capable of blocking the top of the core pipe. By means of the preset downhole filter and the water filtering method, the problem of water deterioration in a water injection well in awater injection string can be solved, downhole filtering of injected water is realized, the injected water is prevented from being contaminated along the way, the concentration of suspended matter inthe injected water is reduced before the injected water is injected into a stratum, and the water quality of the injected water is improved.

Description

technical field [0001] The invention relates to the technical field of petroleum exploitation, and relates to a preset downhole filter capable of filtering injected water downhole and a water filtering method, and is especially suitable for use in water injection wells with poor water quality in low-permeability water drive development reservoirs. Background technique [0002] At present, water injection is widely used in oilfield development. The quality of injected water directly affects the development effect of oil wells. However, the injected water of water injection wells is only equipped with filtering devices at the ground joint station, water injection station, and water injection wellhead. It is not deployed in the downhole, and the water injection string cannot be solved. Internal problems of water quality deterioration in injection wells, such problems mainly include "the treatment capacity at the source does not meet the development needs", "the bacteria in the w...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a preset downhole filter and water filtration method, which can solve the problem of water quality deterioration in injection wells caused by the interior of the water injection pipe string, realize the filtration of injected water in the well, and prevent the injection water from leaking in the water injection pipe string. Pollution along the way is generated in the interior, the concentration of suspended solids in the injected water before being injected into the formation is reduced, and the quality of the injected water is improved.

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