RU2395647C2 - Water filter of well drilled in fine and silty sands - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to construction of water wells operated in water-bearing formations consisting of fine and silty sands. Water well filter drilled in fine and silty sands comprises gravel packing, external perforated well casing and inner string with filtration layer, shoe and packing. External perforated well casing is equipped with additional filtration element representing, for example a screen with pass holes with diametre equal to gravel packing particle size, and settling device. Size of inner string filtration element pass holes equals that of water-bearing sand particles, said filtration element representing multilayer spooling from polymer threads. Note here that inner string shoe incorporates waterproof plug.

EFFECT: increased operation of well at sufficient extraction rate due to less intensive plugging of filtration element during water filtration, ease and high rate of filter replacement.

1 dwg

Description

The invention relates to the field of water well constructions operated in water-containing formations consisting of fine and dusty sands.

One of the main parts of the well for water is a filter, the purpose of which is to keep the walls of the well from collapsing and to prevent particles in the water from entering the pumped water stream.

A well-known design of a well water filter (Handbook of water well drilling edited by D.N. Bashkatov. M .: Nedra, 1979, p. 457, Fig. 11.9), which consists of gravel sprinkling and a filter column. Gravel sprinkling is laid between the water-containing sands and the filter column. The filter column is equipped with an oil seal and check valve. Its working part is made of a perforated pipe, coated on the outside with a filter element in the form of a mesh or wire winding.

The combination in the design of the gravel sprinkler filter and the column with a filter element ensures the stability of the walls of the well and eliminates the penetration of small particles from the aquifer into the pumped water that settle on the surface of the grid and between gravel particles during water filtration.

The disadvantage of this design is that during well operation, such settling of particles leads to constant blockage of the holes of the filter element and the mudding of gravel spatter, which reduces the productivity of the well and shortens its life. Most intensively, these processes occur when the water-bearing rock is represented by fine and silty sands. In addition, the small particle size of the water-bearing rock requires the use of small gravel fractions in the dusting of the filter and the minimum size of the passage openings of the filter element, the filter column, which in turn makes various methods of restoration work to restore the productivity of the well based on processing its filter element and filter filter ineffective zones from the inner cavity of the filter column. It should be noted that the extraction of the filter column in most cases is not possible due to the tight compression of it with a colded dusting.

The closest technical solution to the claimed invention is a well filter for water (G.P. Kvashnin, A.N. Derevyannykh. Water supply for wells with gravel filters. M: Nedra, 1981, p. 202, Fig. 86), which includes: gravel, outer perforated casing and inner string. The inner column is equipped with a shoe with a check valve and a filter element. The coupling of the inner string with the outer perforated casing is carried out using an oil seal.

The presence of an external perforated casing in the well structure ensures the stability of the walls of the well during the formation of an enlarged cavity in the filter zone of the well hydraulically without using a clay solution and then filling it with gravel.

The disadvantage of this device is that filling with gravel not only the broadened cavity around the outer perforated casing, but also the annular space between its inner walls and the outer surface of the inner string makes it possible to restore well productivity when blocking the holes of the filter element and the mudding of gravel sprinkling is still more problematic.

The main objective of the invention is to create a well filter for water, the design features of which can increase the duration of the well’s life without significantly reducing its productivity due to less intensive blockage of the filter element during water filtration and the possibility, when it is clogged, of periodic restoration of permeability by hydraulic treatment, facilitation and acceleration filter replacement.

The essence of the invention lies in the fact that the filter of the well for water drilled into fine and dusty sands consists of gravel sprinkling, an external perforated casing and an inner string, which has a filter element, an oil seal and a shoe with a waterproof plug. The increase in the duration of operation of the specified filter is due to the fact that the outer perforated casing pipe is equipped with an additional filter element. This element can be made in the form of a grid, wire winding, cut-out sheet, etc. The size of the through holes of the additional filter element is equal to the particle size of the gravel sprinkle. At the bottom of the outer perforated pipe, a sump is installed. The filter element that the inner column is equipped with has a hole size equal to particles of water-containing fine and dusty sands. Such characteristics of the filter element can be obtained by using multilayer winding from polymer threads, fabrics, etc. The shoe mounted on the inner column is equipped with a waterproof plug that serves to prevent water from entering the inner column, bypassing the filter element.

The invention is illustrated by the drawing, which shows a vertical section of the filter of the well for water drilled into fine and dusty sands.

The filter includes an outer perforated pipe 1, the perforated part of which is closed by an additional filter element 2, made, for example, in the form of a mesh. An annular gap between the water-containing fine sand 3 and the outer perforated pipe 1 is filled with gravel. In the lower part of the perforated pipe 1, a settling tank 5 is mounted. An inner column 6 with a filter element 7 is installed in the outer perforated pipe 1. The size of the passage openings of the filter element 2 is equal to the size of gravel sprinkling 4, and the filter element, in the form of a multilayer winding of polymer threads, is equal to the dimensions particles of water-containing fine sand 3. The pair of the outer perforated pipe 1 with the inner column 6 is carried out using the stuffing box 8, which acts as a centralizer. The bottom end of the inner column 6 is equipped with a shoe 9 with a waterproof plug 10.

A well filter for water drilled into fine and dusty sands works as follows.

When pumping water from the well with a submersible pump, the water level in it drops below static, and the pressure of the water column in the well becomes lower than the reservoir pressure of the water-containing fine sand. Due to the pressure difference, water from the fine sand 3 surrounding the filter borehole enters its internal cavity, gravel sprinkling 4, an additional filtering element 2, perforation of the outer pipe 1 and the inner column 6, the filtering element 7, and the perforation of the inner column 6 pass sequentially. captures small fractions of sand of the water-containing formation 3, some of which are delayed in gravel sprinkling 4, and the smallest fractions pass through it and an additional filter element 2, which delaying is from falling into the internal space of the well only particles whose size is equal to or greater than the particle size gravel package 4. After passing through the perforations when released into the annular gap between the outer tube 1 and the inner column 2 dramatically reduced water velocity. In this case, part of the small particles contained in it precipitates and enters the sump 5, and the remaining part of the small particles is retained by the filter element 7, the size of the passage openings of which is equal to the particle size of the water-containing fine sand 3. The presence of the stuffing box 8 eliminates the ingress of small particles into the well cavity from an annular gap in the upper part of the inner column 6, and a waterproof plug 10 installed in the shoe 9 does not allow them to get through the lower end of the inner column 6. When the filter element is clogged That 7 as a result of long-term operation of the well, its water permeability is restored by hydraulic methods, in which a pressure is created in the zone of the perforated inner column 6, which exceeds the in-situ pressure of the water-containing fine sand. This hydraulic treatment displaces small fractions of sand from the filter element 7 and deposits them in the sump 5.

During long-term operation of the well, if its productivity after hydraulic treatment is not fully restored, a free climb to the surface is made without gravel backfill and water-containing rock of column 6, the sump 5 is cleaned of deposits of fine sand fractions and the external perforated pipe 1 and gravel are hydraulically treated 4. During such repairs, the filter element 7, raised to the surface, is either cleaned or replaced with a new one, and then inside nyuyu column 6 is mounted in its place in the well cavity.

The use of the proposed filter of the equipment of the water intake part of the well drilled into fine and dusty sands allows, firstly, to extend the effective period of operation of the well without repairing it, and secondly, if necessary, carry out repair work to replace the filter with minimal labor, and over a long period of well operation, the filter can be replaced many times. All of the above makes it possible to obtain a tangible technical and economic effect.

Claims (1)

A well filter for water drilled into fine and dusty sands, including gravel, an outer perforated casing and an inner string with a filter layer, a shoe and an oil seal, characterized in that the outer perforated casing is equipped with an additional filter element made, for example, in the form of mesh, the size of the through holes of which is equal to the size of the particles of gravel sprinkling, and is equipped with a sump, and the size of the through holes of the filter element of the inner column, made in e multilayer winding of polymeric fibers is equal to the particle size of water-bearing sand, the shoe inner column is mounted with a watertight stopper.