RU2729577C1 - Downhole filter - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, particularly, to oil and gas filtration. Downhole filter comprises nipples, a coupling and at least one filter unit comprising a filter element with stringers laid parallel to the axis of the downhole filter between the limit rings, and coils of profiled wire wound on them. Each filtering unit comprises an inner core fitted on it by an external cylinder coaxially with preliminary tightening with radial holes and stringers made integral with the external cylinder. Connection of internal pipe and external cylinder is made through cross-pieces installed inside limiting rings.

EFFECT: higher bending strength while maintaining torsional strength and providing efficient cleaning.

7 cl, 1 tbl, 23 dwg

Description

The invention relates to the oil and gas industry, specifically to oil and gas filtering means.

Known slotted well filter according to the RF patent for useful model No. 71694, IPC E21B 43/08, publ. 03/20/2008

The filter contains a perforated pipe on which longitudinal support elements are installed, on the outer surface of which a wire is wound with the formation of gaps between the turns, while the wire is welded or soldered to the longitudinal elements, and the ratio of the pitch of the longitudinal elements to their height is made in the range from 1.0 up to 10. A filter mesh is installed between the pipe and the longitudinal support elements. A wire is wound between the supporting longitudinal elements and the filter mesh, which acts as a drainage layer. A drainage mesh is installed between the pipe and the filter mesh. A drainage mesh is installed between the longitudinal support elements and the filter mesh.

The disadvantages of the filter are the complexity of the design of the well filter, the laboriousness of manufacture, low reliability and rapid abrasive wear of the filter element.

Known downhole filter according to the RF patent for invention No. 2507384, IPC E21B 43/08, publ. 20.02.2014

This slotted borehole filter contains a perforated carrier pipe and a slotted filter element made of wire wound on longitudinal elements in a spiral, and the cross-section of the wire wound in a spiral is made pentagonal, one of the edges of the wire is made parallel to the longitudinal axis of the filter and forms its outer surface, and each lateral side is made with two edges, the upper ones form a filtering gap, and the lower ones converge, forming an acute angle.

Disadvantages: low strength of the wire of the filter element, which leads to a change in the gaps when running the well screen, and rapid abrasive wear of the "narrowest point" of the filter element.

Known frameless downhole filter according to the RF patent for invention No. 2606470, IPC В21В 43/08, publ. 01/10/2017, prototype.

This frameless downhole filter contains two nipples and at least one filter element, covered by a protective casing having holes and made between the stop rings, in that each filter element is laid on longitudinal elements, and both nipples are welded to the extreme stop rings, an annular casing is installed inside the filter without an annular gap, inside which a means for swirling the extracted product is installed with an annular gap. The filter element can be made slotted in the form of a wire wound on the longitudinal elements in a spiral.

Disadvantages: low bending strength of the well screen.

The task of creating the invention: increasing the bending strength of the well screen while maintaining the torsional strength and ensuring effective cleaning.

Technical results achieved: increased flexural strength and retention of torsional strength and effective cleaning.

The solution to these problems is achieved in a downhole filter containing nipples, a sleeve and at least one filter unit containing a filter element with stringers laid parallel to the axis of the downhole filter between the restricting rings, and profiled wire turns wound around them, characterized in that each the filter unit contains an inner rod, an outer cylinder coaxially mounted on it with a preload with radial holes and stringers made in one piece with the outer cylinder, and the connection of the inner pipe and the outer cylinder is made through crosses installed inside the restricting rings.

The outer diameter of the inner bar can be made from the ratio:

D _vn1 = (0.2 ... 0.3) D _vnf , where:

D _vn1 - outer diameter of the inner rod,

D _vnf is the inner diameter of the filter.

The height of the stringer profile can be made from the ratio:

Н ₂ = (2 ... 5) δ ₂ , where:

Н ₂ - the height of the stringer profile,

δ ₂ - thickness of the outer cylinder.

The thickness of the stringers can be made from the ratio:

δ _c = (0.8 ... 1.0) δ ₂ , where:

δ _c - stringer thickness,

δ ₂ - thickness of the outer cylinder.

The profiled wire can be made of a triangular cross-section with a radius rounding of the apex facing the axis of the well screen.

Radial rounding of the vertex facing the axis of the well screen can be performed from the condition:

R = (0.2 ... 0.25) a, where:

R - radius of rounding of the vertex,

a - the width of the profiled wire.

D ₂ > D _int .

Laying of the outer cylinder with stingers during assembly is made in such a way that the outer diameter of the filter element is less than the outer diameter of the sleeve:

D ₂ > D _int .

The essence of the invention is illustrated in the drawings Fig. 1-23, where:

- in Fig. 1 shows a well filter,

- in Fig. 2 shows the filter element,

- in Fig. 3 shows an inner tube with longitudinal ribs,

- in Fig. 4 shows the outer cylinder with stringers,

- in Fig. 5 shows the end of the outer cylinder with stringers,

- in Fig. 6 shows the end of the longitudinal rib on the inner pipe,

- in Fig. 7 shows the first version of the profiled wire,

- in Fig. 8 shows the second version of the profiled wire,

- in Fig. 9 shows the assembly of the inner pipe and the outer cylinder,

- in Fig. 10 shows the first version of the stringer and its installation in the restraining ring,

- in Fig. 11 shows the second version of the stringer and its installation in the restraining ring,

- in Fig. 12 shows the third version of the stringer and its installation in the restraining ring,

- in Fig. 13 shows the fourth version of the stringer and its installation in the restraining ring,

- in Fig. 14 shows the fifth version of the stringer and its installation in the restraining ring,

- in Fig. 15 shows the sixth version of the stringer and its installation in the restraining ring,

- in Fig. 16 shows view A,

- Fig. 17 shows the restrictive ring in section, the first version,

- in Fig. 18 shows the restrictive ring in section, the second option,

- in Fig. 19 shows the restrictive ring in section, the third option,

- in Fig. 20 shows view B,

- in Fig. 21 shows the first version of the assembly of the filter unit,

- in Fig. 22 shows the second version of the assembly of the filter unit,

- in Fig. 23 shows a well screen with two filtering blocks.

Description notation

nipple 1,

clutch 2,

centralizer 3,

filter unit 4,

filter element 5,

stringer 6,

restrictive ring 7,

profiled wire 8,

weld 9,

contact welding 10,

inner cavity 11,

inner rod 12,

thread 13,

outer cylinder 14,

radial holes 15,

contact surface 16,

cross 17,

outer cage 18,

inner clip 19,

fairings 20,

cutout of the end of the stringer 21,

turnkey head 22,

axial cavity 23,

inner groove 24,

inner end 25,

outer groove 26,

outer end 27,

inner chamfer 28,

outer chamfer 29,

internal weld seam 30,

radial cut 31,

inner surface 32,

inlet end 33,

exit end 34,

inlet fairing 35,

outlet fairing 36,

intermediate ring 37.

H ₀ - the height of the filter element in the cross section,

H ₁ - main gap,

Н ₂ - the height of the stringer profile,

H ₃ - the height of the cross-section of the profiled wire.

D ₁ - inner diameter of the inner pipe,

D ₂ - inner diameter of the outer cylinder,

D _m - outer diameter of the coupling,

D _f - outer diameter of the filter element,

δ ₁ - thickness of the inner pipe,

δ _с - stringer thickness,

δ ₂ - thickness of the outer cylinder,

δ _pr - lateral gap between the rows of profiled wire,

t - step of installing stringers,

a - the width of the profiled wire,

R - radius of rounding of the contact surface of the profiled wire,

r ₁ - radius of rounding of the apex of the cross-section of the profiled wire.

The downhole filter (Fig. 1 ... 23) is designed for oil or gas purification. 3

The downhole filter (Fig. 1) contains nipples 1, a sleeve 2 on the upper nipple 1, and a centralizer 3 can be installed. Between the nipples 1 filter blocks 4 are installed in the form of filter elements 5.

The filter element 5 (Fig. 2) contains stringers 6, laid parallel to the axis of the OO downhole filter between the limiting rings 7, and wound on them turns of profiled wire 8 of triangular section.

Connections of nipples 1 with stop rings 6 and stop rings 7 with filter elements 5 are made with welds 9.

The connection of the profiled wire 8 with the stringers 6 is made by resistance welding 10.

An internal cavity 11 is formed inside the well screen, into which the purified production product enters.

The height of the profile of the stringers 6 can be made from the ratio:

Н ₂ = (3 ... 5) δ _с , where:

Н ₂ - the height of the profile of the stringer 6,

δ c - stringer thickness 6.

With such a thickness of the stringer 6, its weight decreases by 4 ... 5 times, and the bending strength increases by 7 times, provided that the corresponding height of the stringer profiles is 6 N ₁ .

The assembly of stringers 6 is shown in FIG. 5, 18 and 19.

Proof of the optimality of the specified ratio of dimensions for determining the height of the stringer Н ₂ .

It is known from the resistance of materials (for a rectangular profile):

W is the moment of resistance to bending,

Н ₂ - the height of the stringer 5,

δ ₂ - thickness of stringer 5.

From this formula it follows that with an increase in the height of the profile of the stringer 6 - H _2, its bending resistance increases with a quadratic dependence. However, the upper redistribution is limited by the outer diametrical dimension of the downhole filter: it is impossible to make the filter element 4 with a diameter greater than the outer diameter of the sleeve 7 D _m due to the possibility of destruction of the filter element 5 when running into the well.

A more detailed justification of the height of the profile of stringers 6 using some data, partially borrowed from GOST 633-80. Tubing pipes and couplings for them. Specifications are given in table. 1.

It is also possible to use pipes in accordance with GOST 632-80 in practice. Casing pipes and couplings for them. Technical conditions.

From table. 1 it follows that the height of the filtering element is H ₀ = 13.5 ... 16.0 mm.

With the height of the profiled wire 7 - H ₃ equal to 3 mm, taking into account that H ₀ = H ₃ + H _2, we have the height H ₂ (Fig. 3) of the profile of stringers 6:

The allowed maximum stirnger height 7 is in the range:

H ₂ = 10.5 ... 13.0 mm, which is quite enough for the manufacture of an outer pipe with stringers.

For example, with δ ₂ = 1.0 mm and δ _c = 1.0 mm, we have that the height of the profile of the stringers 6 will be in the range:

H ₂ = 3.0 ... 5.0 mm.

With δ ₂ = 2.0 mm and δ _c = 2.0 m

H ₂ = 6.0 ... 10.0 mm, which is slightly less than the maximum permissible range H ₂ = 10.5 ... 13.0 mm.

In addition, the downhole filter contains (Fig. 5 and 6) an inner rod 12 with a thread 12, mounted on it coaxially an outer cylinder 14 with radial holes 15 and stringers 6, made integral with the outer cylinder 14. The contact surfaces 16 of the stringers 6 are in contact with the profiled wire 8 and connected to it by resistance welding 10 (Fig. 2, 5 and 6).

There are two possible versions of the profiled wire 8 of FIG. 7 and 8.

According to the first option, the profiled wire 8 is rounded at the point of contact with the stringers 6 with radius R.

Radial rounding of the vertex facing the axis of the well screen can be performed from the condition:

R = (0.2 ... 0.25) a, where:

R - radius of rounding of the vertex,

a - the width of the profiled wire.

According to the second option (Fig. 8), it is possible to use a wire of a trapezoidal cross-section, while its smaller base is directed to the axis of the downhole filter OO.

The inner diameter of the inner cylinder 14 can be made from the ratio:

D ₁ = (0.2 ... 0.3) D ₂ , where:

D ₁ - inner diameter of the inner rod 12,

D ₂ - inner diameter of the outer cylinder 14.

With such size ratios, the blockage of the filter section with the inner rod 12 is insignificant, and if the inner rod 12 is made in the form of a pipe and is open from the inlet and outlet ends, then the blockage will be even less. If necessary, the ends can be closed, respectively, with fairings 20.

When the fairings 20 are installed, the hydrodynamic rubbing inside the well screen in the inner cavity 11 is significantly reduced.

FIG. 5 shows a stringer 6 with a cutout of the end of the stringer 21 of rectangular shape.

FIG. 6 shows an internal rod 12 with threads 13 at the ends and with a thickening for the key 22 and with an internal cavity 23.

For more convenience, radial cutouts 31 can be made between the stop rings 6 in one embodiment (Fig. 17).

There are 4 options for the downhole filter (Fig. 8 ... 14)

FIG. 8 shows the first version of the well filter:

D ₂ ≥D _ext , where:

D ₂ - inner diameter of the outer pipe 13,

D _vn is the inner diameter of the filter.

FIG. 9 shows the second version of the well filter:

D ₂ = D _int ,

Where:

D ₂ - inner diameter of the outer pipe 13,

D _vn is the inner diameter of the filter.

FIG. 10 shows the third version of the well filter:

D ₂ ≤D _corolla,

Where:

D ₂ - inner diameter of the outer pipe 13,

D _vn is the inner diameter of the filter.

FIG. 11 shows the end of the stringer 5, the second option and its installation in the restricting ring 6, in which:

_VNS D <D _ext.

FIG. 11 shows a third embodiment of FIG. eleven:

D ₂ <D _int .

FIG. 12 shows the first version of the well filter:

D ₂ ≥D _corolla,

Where:

D ₂ - inner diameter of the outer pipe 13,

D _vn is the inner diameter of the filter.

in fig. 14 shows a view B of the stop ring 6. The stop ring 6 has an external chamfer 22 at a larger diameter of the outer end 23 and an annular recess 24 at a smaller diameter for joining to the nipple 1.

FIG. 14 shows view B,

FIG. 15 shows the first version of the stop ring 7.

FIG. 16 shows the second version of the stop ring 7.

FIG. 17 shows a third version of the restraining ring 7 with radial pops 31 and a conical inner surface 32 in the form of a frusto-cone. FIG. 18 shows a view B of the stop ring 7, the third version.

FIG. 18 and 19 show two variants of the assembly of the filter units 4. In this case, in the variant of FIG. 19 only welds 9 are used on the outside. And in the embodiment of FIG. 20 and from the outside - welds 9 and internal welds 30. The second option has a higher tensile strength.

Well screen assembly

When assembled separately (Fig. 1 ... 23), nipples 1, stop rings 7 and filter elements 5 are made.

The filtering elements 5 are assembled on a mandrel (not shown) on which the inner cage 19 with stringers 6 is installed and a profiled wire 8 is wound on them, periodically welding it to the stringers 6 by contact welding 10 (Fig. 12).

The filter elements 5 after being assembled are welded on both sides to the restricting rings 7 with welding seams 9 (Figs. 1, 2 and 19, 20).

By rotating the inner rod 12 along the threads 13 having opposite directions (right and left), axial tension is created in the stringers 6. This improves the bending and compression resistance of the well screen.

Then the filter elements 5 are welded to the restricting rings 7 using internal welding seams 30. The nipples 1 are inserted into the inner grooves 24 (Figs. 1, 2 and 19, 20) and welded to the restricting rings 7 also with welding seams 9 (Figs. 1 and 2 ). It is possible to manufacture a well filter with two or more filtering blocks 4 (Fig. 21) connected by intermediate rings 37.

WELL FILTER OPERATION

The downhole filter is designed to clean oil or gas from impurities (Fig. 1 ... 23). For this, the downhole filter is installed in the production casing (not shown). Oil (gas) through the gap δ ₁ between the turns of the profiled wire 8 and then through the gaps between the stringers 6 - δ ₂ enters the inner cavity 11 with a high degree of purification.

The degree of filtration depends mainly on the gap δ ₁ and is set by the customer, usually in the range from 0.1 to 1.0 mm. At the same time, deformation of the turns of the profiled wire 8 is not permissible either during manufacture or during transportation and lowering of the well screen into the well. This is achieved by the contact of the profiled wire 8 with the stringers 6 during welding, their welding without drawing the profiled wire 6 due to the larger area of their contact with each other.

Passing through the gaps δ ₂ between the stringers 6 (Fig. 10) into the inner cavity 11, the product is cleaned.

The proposed design provides improved filtration due to the stability of the lateral gap between the rows of profiled wire δ ₁ (Fig. 10) and increases its strength due to the proposed profile of the stringers 6 and the profiled wire 8.

When using several filter units 4, their tensile strength, twisting and vibration load increases.

Application of the invention allowed:

increase the bending strength of the well screen and maintain tensile and torsional strength,

- to increase the strength of the well screen when exposed to bending and compressive loads,

- to improve the cleaning of the extracted product by reducing the deformation of the turns of the profiled wire during welding and when running the well screen into the well.

Claims (21)

1. A downhole filter containing nipples, a sleeve and at least one filter unit containing a filter element with stringers laid parallel to the axis of the downhole filter between the restricting rings, and winding of profiled wire on them, characterized in that each filter unit contains an inner rod, coaxially mounted on it with a preload, an outer cylinder with radial holes and stringers made in one piece with the outer cylinder, and the connection of the inner pipe and the outer cylinder is made through crosses installed inside the restraining rings. 2. The downhole filter according to claim 1, characterized in that the outer diameter of the inner rod is made from the ratio: D _vn1 = (0.2 ... 0.3) D _vnf , where: D _vn1 - outer diameter of the inner rod, D _vnf is the inner diameter of the filter. 3. Downhole filter according to claim 1, characterized in that the height of the stringer profile is made from the ratio: Н ₂ = (2 ... 5) δ ₂ , where: Н ₂ - the height of the stringer profile, δ ₂ - thickness of the outer cylinder. 4. Downhole filter according to claim 1, characterized in that the thickness of the stringers is made from the ratio: δ _c = (0.8 ... 1.0) δ ₂ , where: δ _с - stringer thickness, δ ₂ - thickness of the outer cylinder. 5. The downhole filter according to claim 1, characterized in that the profiled wire is made of a triangular cross-section with a radius rounding of the apex facing the axis of the downhole filter. 6. The downhole filter according to claim 7, characterized in that the radius rounding of the apex facing the axis of the downhole filter is made from the condition: R = (0.2 ... 0.25) a, where: R - radius of rounding of the vertex, a - the width of the profiled wire. D ₂ > D _int . 7. A well filter according to claim 1, characterized in that the outer cylinder with stingers is laid in such a way that the outer diameter of the filter element is less than the outer diameter of the sleeve: D ₂ > D _int .

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