RU2729298C1 - Downhole filter and its cleaning method - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: group of inventions relates to oil and gas industry, specifically to means of oil and gas filtration. Downhole filter comprises nipples, a coupling and 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, inner core installed inside filtering element, external cylinder in the form of a flat spiral with stringers laid on it, made of elastic material, two cross pieces: lower and upper, installed inside the limit rings. High-pressure cylinder with BRS union is connected to the upper crosspiece. Inner rod is connected with lower crosspiece by rigid connection, and with upper crosspiece with possibility of inner rod sliding along sliding fit. Stringers height is made from the following ratio: H=(2…5)δ, where His stringer height, δis thickness of outer cylinder.EFFECT: reducing weight, increasing bending strength while maintaining torsional strength; providing efficient cleaning.9 cl, 23 dwg

Description

The group of inventions relates to the oil and gas industry, specifically to the means for filtering oil and gas.

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.

Achieved technical result: weight reduction, increase in bending strength while maintaining torsional strength and ensuring high-quality filter flushing.

The solution to this problem is achieved in a downhole filter containing nipples, a sleeve and 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, in that it contains an inner rod installed inside the filter element, an outer cylinder in the form of a spiral with radial holes and with stringers laid on it, made of elastic material, two crosses: lower and upper, installed inside the restraining rings, while the connection with the lower cross is made rigid, with the upper one - with the possibility of mutual axial movement and to it a high-pressure cylinder with a quick coupling is connected, the inner rod is connected to the lower cross by a rigid connection, and to the upper cross with the possibility of an axial inner rod along a sliding fit, while the height of the stringers is made from the ratio:

Н ₂ = (2 ... 5) δ ₂ where:

Н ₂ - stringer height,

δ ₂ - thickness of the outer cylinder.

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 thickness of the stringers can be made from the ratio:

δ _c = (0.8 ... 1.0) δ ₂ , where:

δ _с - 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 is the radius of rounding of the vertex,

a - the width of the profiled wire.

Laying the outer cylinder with stingers during assembly can be done in such a way that the inner diameter of the outer cylinder is larger than the inner diameter of the filter:

D ₂ > D _int .

Laying the outer cylinder with stingers during assembly can be done 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 solution of these problems is achieved in the method of cleaning the well filter by acting on the filter element, by the fact that the filter element is influenced by a high-pressure cylinder, temporarily lengthening the filter element and increasing the filtering gaps between the rows of profiled wire, then the well filter is washed by supplying flushing fluid from the cavity of the production string ...

When cleaning the well filter, the filtering gaps can be increased by 2 ... 3 times.

The essence of the group of inventions is illustrated in the drawings of FIG. 1-23, where:

- in Fig. 1 shows the 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,

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

- 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 a coiled tubing attached to it.

Description notation:

nipple 1,

clutch 2,

centralizer 3,

filter element 4,

stringer 5,

stop ring 6,

profiled wire 7,

welding seam 8,

adhesive joint 9,

inner cavity 10,

inner core 11,

lower cross 12,

upper crosspiece 13,

rigid connection 14,

sliding fit 15,

high pressure cylinder 16,

outer cylinder 17,

flat spiral 18,

outer cage 19,

inner cage 20,

cross stand 21,

inner groove 22,

inner end 23,

external groove 24,

outer end 25,

inner chamfer 26,

outer chamfer 27,

inner weld 28,

second inner groove 29,

inner surface 30,

inlet fairing 31,

quick-connect fitting 32,

mating union quick-release coupling 33,

coiled tubing 34,

lower stop 35,

top stop 36,

shoe 37,

surface 38,

production casing 39,

high pressure supply system 40,

flushing fluid supply system 41.

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 ₃ - the gap between the turns of the spring,

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.

The filter element 4 (Fig. 2) contains stringers 5, laid parallel to the axis of the OO downhole filter between the limiting rings 6, and wound on them turns of profiled wire 7 of triangular section.

A feature of the claimed invention is that the stringers 5 are made of an elastic material capable of stretching in length by 3 ... 7%, for example, of plastic.

Connections of nipples 1 with stop rings 6 and stop rings 6 with filter elements 4 are made with welds 8.

The connection of the profiled wire 7 with the stringers 5 is made with an adhesive joint 9.

An internal cavity 10 is formed inside the well screen, into which the purified produced product enters.

The height of the stringers 5 can be made from the ratio:

Н ₂ = (3 ... 5) δ _с , where:

Н ₂ - the height of the stringer 5,

δ _с - stringer thickness 5.

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

The assembly of stringers 5 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,

H ₂ - stringer height 5,

δ ₂ - thickness of stringer 5.

From this formula it follows that with an increase in the height of the stringer 5 - 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 because of the possibility of destruction of the filter element 4 when running into the well.

More detailed substantiation of the height of stringers 5 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 in practice pipes according to GOST 632 - 80. 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, given that H ₀ = H ₃ + H ₂ we have the height H ₂ (Fig. 3) of stringers 5:

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 stringers 5 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 well screen contains (Fig. 5 and 6) an inner rod 11, a lower cross 12 and an upper cross 13, in which the inner rod 11 is installed.

In this case, the inner rod 11 is connected to the lower cross 12 by a rigid connection 14, and to the upper cross 13 with the possibility of axial movement of the inner rod 11 along a sliding fit 15. A high pressure cylinder 16 is connected to the inner rod 11 from the side of the upper cross 13.

Coaxially to the inner rod 11 there is an outer cylinder 17 with radial holes 18 and stringers 5, made integral with the outer cylinder 17.

The stringers 5 are in contact with the profiled wire 7 and are connected to it with an adhesive bond 9 (Figs. 2, 5 and 6).

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

According to the first option, the profiled wire 7 is rounded at the point of contact with the stringers 5 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 outer diameter of the inner rod 11 can be made from the ratio: D ₁ = (0.2 ... 0.3) D ₂ , where:

D ₁ - outer diameter of the inner rod,

D ₂ - inner diameter of the outer pipe.

With such aspect ratios, the blockage of the filter section with the inner rod 11 is significant.

When installing the inlet fairing 31, the hydrodynamic losses inside the well screen in the inner cavity 10 are significantly reduced.

The lower and upper crosses 12 and 13 are identical in design and contain an outer cage 19, an inner

FIG. 5 shows the end of the stringer 5 with a rectangular cut-out of the stringer. FIG. 6 shows an internal rod 11 with a rigid connection 14 and a sliding fit 15 at the ends.

There are 5 options for the downhole filter (Fig. 9 ... 15)

FIG. 9, 10 and 13 show the first version of the well filter:

D ₂ ≥ D _int ,

Where:

D ₂ - inner diameter of the outer pipe 17,

D _vn is the inner diameter of the filter.

In the crosses 12 and 13 (Fig. 9), the crosspieces 21 are made. They are made radially between the outer and inner cages 19 and 20 of both crosses 19 and 20. In Figs. 11 and 12 show the second version of the well screen:

D ₂ = D _int ,

Where:

D ₂ - inner diameter of the outer pipe 17,

D _vn is the inner diameter of the filter.

FIG. 14 ... 16 shows the third version of the well filter:

D ₂ ≤ D _int ,

Where:

D ₂ - inner diameter of the outer pipe 17,

D _vn is the inner diameter of the filter.

FIG. 17 shows the stop ring 6, the first option.

FIG. 18 shows a stop ring 6, the second option.

FIG. 19 shows a third version of the restraining ring 6 with an inner surface 30 of a conical shape in the form of a frusto-cone.

FIG. 20 shows a view B of the restraining ring 6, the third version.

FIG. 21 and 22 show two options for assembling filter elements 4.

In this case, in the embodiment of FIG. 21, in the crosses 12 and 13, only the inner clips 20 are used. In the embodiment of FIG. 22 outer clips 19 and inner clips 20.

FIG. 23 shows the connection of the coiled tubing 34 using the BRS 32 union and the BRS 33 mating union.

The adjustment of the initial position of the filter element 4 can be performed in any way. For example, on the inner rod 11, lower and upper stops 35 and 36 can be made (Figs. 9 and 23),

The cleaning system includes a shoe 37, made on the surface 38 and connected to the production string 39, a high pressure supply system 40 and a system for supplying flushing fluid 41.

Well screen assembly

When assembled separately (Fig. 1 ... 23), nipples 1, stop rings 6 and filter elements 4 are made.

The filter elements 4 are assembled on a mandrel (not shown) on which the inner cylinder 17 with stringers 5 made of elastic material is installed and profiled wire 7 is wound on them, periodically gluing it to the stringers 5 with adhesive joints 9 (Fig. 12).

The filter elements 4 after being assembled are welded on both sides to the boundary rings 6 with welding seams 8 (Figs. 1, 2 and 19, 20).

Using a rigid connection 14 and stops 35 and 36, the filter element 4 is assembled and inside it, from the side of the upper crosspiece 13, a high-pressure cylinder 16 is attached.

Before or later, the filter elements 4 are welded to the stop rings 6 by means of internal welding seams 28.

The nipples 1 are inserted into the inner grooves 22 (Figs. 1, 2 and 19, 20) and welded to the restricting rings 6 with welding seams 8 (Figs. 1 and 2).

WELL FILTER OPERATION

The downhole filter is designed to clean oil or gas from impurities (Fig. 1 ... 23). To do this, the well filter is installed in the production string 32. Oil (gas) through the gap δ ₁ between the turns of the profiled wire 7 and then through the gaps between the stringers 5 - δ ₂ and the gaps between the turns of the flat spring 18 δ ₂ enters the inner cavity 10 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. In this case, deformation of the turns of the profiled wire 7 is not permissible, neither during manufacture, nor during transportation and lowering of the downhole filter into the well. This is achieved by contacting the profiled wire 7 with the stringers 5 when gluing it without drawing the profiled wire 7 due to the larger area of their contact with each other.

Passing through the gaps δ ₁ between the stringers 5 (Fig. 10) into the inner cavity 10 of the well screen, the produced product is purified.

During operation, the cavity between the profiled wire 7 and the outer cylinder 17 in the form of a flat spring 18 is clogged with foreign particles.

To clean the filtering element 2 of the well filter through the production string 39 (Fig. 23), the coiled tubing 34 is dropped with the counterplug quick-disconnect connection BPS 33, which is connected to the quick-disconnect fitting BPS 32. High pressure supply systems 40 and the flushing fluid supply system 41 are assembled (Fig. . 23).

After that, high pressure of liquid or gas is fed through the high-pressure supply system 40 to the high-pressure cylinder 16, which lengthens the filter element 4 by 3 ... 7% and thereby increasing the gaps δ ₁ .

Then, the flushing fluid is fed into the cavity 10 of the well filter, while the filter element 4 is flushed.

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 and material of stringers 5 and profiled wire 7.

Allows you to periodically carry out high-quality flushing of the well filter.

When using such filter elements 4 with a pre-axial load increases their tensile strength, torsional strength and vibration load. Application of the invention allowed:

- reduce the weight of the downhole filter by 30 ... 50% while increasing its bending strength and maintaining 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 (23)

1. A downhole filter containing nipples, a sleeve and a filter element with stringers laid parallel to the axis of the downhole filter between the limiting rings, and coils of profiled wire wound around them, characterized in that it contains an inner rod installed inside the filter element, an outer cylinder in the form spirals with radial holes with stringers laid on it, made of elastic material, two crosses: lower and upper, installed inside the restraining rings, a high-pressure cylinder with a quick coupling is connected to the upper cross, the inner rod is connected to the lower cross by a rigid connection, and to the upper cross with the possibility of axial movement of the inner rod along a sliding fit, while the height of the stringers is made from the ratio: Н ₂ = (2 ... 5) δ ₂ , where H ₂ is the stringer height, δ ₂ - thickness of the outer cylinder. 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 is the 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 thickness of the stringers is made from the ratio: δc = (0.8 ... 1.0) δ ₂ , where δ _c is the thickness of the stringer, δ ₂ - thickness of the outer cylinder. 4. 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. 5. The downhole filter according to claim 7, characterized in that the radius rounding of the vertex facing the axis of the downhole filter is made from the condition: R = (0.2 ... 0.25) a, where R is the radius of rounding of the vertex, a - the width of the profiled wire. 6. Downhole filter according to claim 1, characterized in that the laying of the outer cylinder with stringers during assembly is made in such a way that the inner diameter of the outer cylinder is larger than the inner diameter of the filter: D ₂ > D _ext . 7. The well filter according to claim 1, characterized in that the outer cylinder with stringers is laid in such a way that the outer diameter of the filter element is less than the outer diameter of the sleeve: D _m > D _f . 8. A method for cleaning a downhole filter according to claim 1 by acting on a filter element, characterized in that a high pressure cylinder acts on the filter element, temporarily lengthening the filter element and increasing the filtering gaps between the rows of profiled wire, then the downhole filter is washed by supplying flushing fluid from the cavity production casing. 9. A method for cleaning a downhole filter according to claim 8, characterized in that when cleaning a downhole filter, the filtering gaps are increased by 1.5 ... 2.0 times.

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