RU2446275C1 - Slot-type well strainer - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: slot-type well strainer includes perforated tube on which filter elements containing stringers to outer surface of which wire is welded so that gaps are formed between coils are installed. At least two filter elements are used. Spring is installed between each pair of filter elements.

EFFECT: eliminating thermal stresses in filter elements.

10 cl, 9 dwg

Description

The invention relates to means for ensuring oil and gas production.

Known downhole filter according to the patent of the Russian Federation for invention No. 2079638, containing a perforated pipe and a filter element.

Disadvantage: the possibility of damage to the filter element during transportation and descent into the well.

A well-known well filter according to A. St. USSR No. 1645470, containing a perforated pipe, on which is laid a wire filter element made of wire with protrusions. The wire is not welded to the longitudinal elements.

The protrusions placed quite often on the wire provide a constant gap between the rows - δ, which is maintained at small deforming loads that occur during transportation and lowering of the slotted downhole filter into the well. At high loads, it is possible to displace several rows of wire and form an open gap of a width of several mm, through which large foreign particles will pass.

Known slotted well filter according to the patent of the Russian Federation for utility model No. 71694, prototype. This downhole filter contains a perforated pipe on which a filter element is installed containing stringers, on the outer surface of which a wire is wound and welded with the formation of gaps between the turns. Stringers are also welded to the perforated pipe. In addition, the perforated pipe, stringers and wire are usually made of different materials. The material for the pipe is determined by the relevant GOSTs, the wire is made of stainless steel, and the stringers are made of carbon, easily welded cheap steels.

Disadvantage: the occurrence of thermal stresses in the weld of the rings and the destruction of the weld caused by different coefficients of thermal expansion of the material of the pipe, stringers and wire.

The objective of the invention is the elimination of axial loads in welds caused by different coefficients of linear expansion of the filter element and the filter pipe.

The solution to this problem was achieved in a slotted well filter containing a perforated pipe on which filter elements containing stringers are installed, the wire is welded to the outer surface with the formation of gaps between the turns, characterized in that at least two filter elements are used, and between each pair of filter elements elements mounted spring. Sealing plugs are installed in the holes of the perforated pipe. The downhole filter contains the coupling and nipple parts. Springs can be made in the form of elastic curved plates. Springs can be made in the form of split bushings. Springs can be made in the form of a wire spiral. Springs can be made in the form of a set of Belleville springs. On the side of the coupling and nipple parts, the restrictive rings are fixedly fixed on the perforated pipe. The filter elements, at least on one side, are fixed on the intermediate rings, which are mounted on the perforated pipe with the possibility of axial movement.

The invention is illustrated in figure 1 ... 11, where:

- figure 1 shows the slotted well filter with two filtering elements in the Assembly,

- figure 2 shows the slotted well filter with three or more filter elements,

- figure 3 shows a view without traffic jams,

- figure 4 shows a view of a with traffic jams,

- figure 5 shows a section bB,

- Fig.6 and 7 shows an embodiment of the spring in the form of elastic curved plates,

- on Fig and 9 shows an embodiment of the spring in the form of a split sleeve,

- figure 10 shows an embodiment of a spring in the form of a wire spiral,

- figure 11 shows an embodiment of a spring in the form of a set of Belleville springs.

The proposed design of the slotted well filter (Fig. 1 ... 11) contains a perforated pipe 1 with holes B and has a coupling part 2 and a nipple part 3. At least two filter elements 4 made of wire 5 wound on a perforated pipe are placed stringers 6 with the formation of gaps - δ and welded or soldered to them.

Possible installation in the holes In the sealing plugs 7 (figure 4).

Between the coupling part 2 and the filter elements 4, as well as between the nipple part 3 and the filter elements 4, restriction rings 8 are installed. The restriction rings 8 are rigidly connected to the perforated pipe 1, for example, by welding. At both ends of each filter element 4, intermediate rings 9 are installed. Intermediate rings 9 are mounted on the perforated pipe 1 with the possibility of axial movement. Between all the filter elements 4 springs 10 are installed.

The springs 10 can be made of any design known in the art. For example, there are several versions of the springs (Fig.6 ... 11). An embodiment of a spring in the form of elastic curved plates is shown in Figs. 6 and 7, an embodiment of a spring in the form of a split sleeve is shown in Figs. 8 and 9, an embodiment of a spring in the form of a wire spiral is shown in Fig. 10 and Fig. 11 shows an embodiment spring designs as a set of Belleville springs.

If two filter elements 4 are used (FIG. 1), they contain an upper and lower filter elements 11 and 12, each of which has one intermediate ring, 9, made with the possibility of axial movement. If three or more filtering elements 4 are used (FIG. 2), the downhole filter has one or more middle filtering elements 13, the design of which differs from the design of the filtering elements 11 and 12 in that they contain intermediate rings 9 on both sides.

During operation, a downhole filter is installed as part of a casing string in the region of an oil or gas reservoir. The produced product passes through slots 8, the size of which is determined by the customer, depending on the viscosity of the product in the field. Usually δ = 0.1 ... 1.0 mm. On the filtering elements 4 there is a filtration of the produced product, which through holes B enters the perforated pipe 1.

At high temperatures of the produced product, the perforated pipe 1 and the filter elements 4 are lengthened, but due to the use of different materials - by a different amount. The spring 10 is compressed (or straightened) and compensates for the different linear expansion of the filter parts. This completely eliminates the occurrence of thermal stresses.

The application of the invention will allow:

1. To prevent the destruction of welds due to thermal stresses in the filter elements after installing the slotted well filter in the well.

2. To simplify the design and manufacturing technology of the filter.

Claims (10)

1. A slotted well filter containing a perforated pipe, on which filter elements containing stringers are installed, the wire is welded to the outer surface with the formation of gaps between the turns, characterized in that at least two filter elements are used, and a spring is installed between each pair of filter elements . 2. The slotted well filter according to claim 1, characterized in that sealing plugs are installed in the holes of the perforated pipe. 3. The slotted downhole filter according to claim 1, characterized in that it contains a coupling and nipple parts. 4. The slotted well filter according to claim 1, characterized in that the springs are made in the form of elastic curved plates. 5. The slotted well filter according to claim 1, characterized in that the springs are made in the form of split sleeves. 6. The slotted well filter according to claim 1, characterized in that the springs are made in the form of a wire spiral. 7. The slotted well filter according to claim 1, characterized in that the springs are made in the form of a set of Belleville springs. 8. The slotted downhole filter according to claim 3, characterized in that the restriction rings are fixedly fixed on the perforated pipe from the sleeve and nipple parts. 9. The slotted well filter according to claim 8, characterized in that the upper and lower filter elements are fixed on one side on the intermediate rings, which are mounted on a perforated pipe with the possibility of axial movement. 10. The slotted well filter according to claim 9, characterized in that the intermediate filter elements on both sides are fixed on the intermediate rings, which are mounted on a perforated pipe with the possibility of axial movement.

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