WO2003091535A1

WO2003091535A1 - Sand screen having a multiple welded wedge-wire structure

Info

Publication number: WO2003091535A1
Application number: PCT/JP2003/004800
Authority: WO
Inventors: Tadayoshi Nagaoka
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-04-26
Filing date: 2003-04-16
Publication date: 2003-11-06
Anticipated expiration: 2004-10-26
Also published as: JP2003314183A; AU2003230238A1

Abstract

A cylindrical screen for a horizontal or inclined well having a multiple welded wedge-wire structure includes a plurality of support rods (2) extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen, a spiral wedge-wire (3) wound about the outside surface of the support rods (2) so as to form a slit (3a) of a predetermined width; and a plurality of linear wedge-wires (4) extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction on the outside surface of the spiral wedge-wire (3) so as to form slits (4a) of a predetermined width. The linear wedge-wires (4) are welded directly to the spiral wedge-wire.(3).

Description

DESCRIPTION

SAND SCREEN HAVING A MULTIPLE WELDED WEDGE-WIRE STRUCTURE

Technical Field

This invention relates to a well screen for a horizontal or inclined well and, more particularly, to a well screen for a horizontal or inclined oil well capable of coping with erosion of a screen wire caused by collision of sand grains accompanying crude oil flowing into the well with the screen wire.

Background Art

There has recently been an increasing tendency in the field of a well for collecting crude oil to substituting a conventional vertical well formed by digging the ground vertically from the ground surface to the oil stratum by a horizontal or inclined well. FIG. 12 shows one of such horizontal or inclined well 100 which is formed by digging the ground from a vertical portion 100a through a curved portion 100b to a horizontal or inclined portion 100c which extends in the horizontal or inclined direction along the oil stratum. Since this type of horizontal or inclined well has a screen section for collecting oil which is several time as long as a conventional vertical well, the horizontal or inclined well has the advantage that it has a superior production efficiency which is several times as large as that of the vertical well.

There is generally a large gap between a well bore and a cylindrical screen and, when crude oil flows into the well, sand grains flow out of the oil stratum with crude oil and collide with the slit portion of the screen. Collision of sand grains with the screen causes erosion of the screen wire as the screen is used over a long period of time with the result that the screen ceases its proper function of preventing sand grains from entering in the screen.

For preventing such erosion of the screen wire, a general practice adopted in the industry is, as shown in FIG.13, to fill gravel 140 in an annulus between a well bore 120 and a cylindrical screen 130 so that when crude oil flows into the well in the direction of the arrow B, sand of the oil stratum does not move and therefore does not collide with the screen wire.

In a horizontal or inclined well, however, no technique has been developed yet for filling gravel in a gap between a well bore and a cyhndrical screen and, accordingly, as shown in the section of FIG.14A and the section of FIG. 14B taken along lines A-A in FIG. 14A, a cavity 150 is produced in the horizontal portion 100c between the top portion of a cylindrical screen 130 and a well bore 120 and there occurs inevitable erosion of the screen due to collision with sand grains accompanying the flow of the oil in the direction of the arrow B. No effective means for preventing such invasion of sand grains into the screen after use of the screen over a long period of time has not been found yet.

It is, therefore, an object of the prsent invention to provide a cylindrical screen for a horizontal or inclined well capable of preventing invasion of sand into the screen notwithstanding use of the screen over a long period of time.

Disclosure of the Invention

For achieving the above described object of the invention, there is provided a cylindrical screen for a horizontal or inclined well having a multiple welded wedge-wire structure comprising: a plurality of support members extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen; a spiral wedge-wire wound about the outside surface of the support members so as to form a slit of a predetermined width; and a plurahy of linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction on the outside surface of the spiral wedge -wire so as to form shts of a predetermined width, said linear wedge-wires being welded directly to the spiral wedge-wire.

According to the invention, even in the event that an opening is formed in the outside wires due to erosion caused by collision of sand grains with the wire after use of the screen over a long period of time, the inside inside wire can prevent further invasion of the sand grains and, therefore, invasion of the sand grains into the screen can be prevented for a long period of time without filling gravel in the cavity between the well bore and the cyhndrical screen.

Further, since the outside linear wedge-wires are welded directly to the inside spiral wire without support rods interposed between the outside linear wedge-wires and the inside spiral wire, the inside spiral wire functions as the support rods for the outside linear wedge- ires and, therefore, total thickness of the cylindrical screen can be held at the minimum notwithstanding the fact that the cylindrical screen is of a multiple wire structure. Accordingly, the inner diameter of the cylindrical screen is not reduced significantly when the cylindrical screen having an outer diameter matching the well bore has been installed and, as result, a well of a high productivity can be installed.

In one aspect of the invention, said support members are support rods.

In another aspect of the invention, said support members are linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form slits of a predetermined width.

According to this aspect of the invention, the support members function as a screen as well as support members for the spiral wire and, accordingly, the life of the cyhndrical screen can further be prolonged.

In another aspect of the invention, the cylindrical screen further comprises an outer spiral wedge-wire wound about the outside surface of the linear wedge-wires so as to form a slit of a predetermined width, said outer spiral wedge-wire being welded directly to the linear wedge-wires.

In another aspect of the invention, the cylindrical screen further comprises a plurality of outer linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form shts of a predtermined width, said outer linear wedge-wires being welded directly to the outer spiral wedge-wire. According to this aspect of the invention, since there are provided the outer linear wedge-wires extending in the axial direction of the screen, the cylindrical screen can be inserted smoothly into a long horizontal well whereby installation of the cylindrical screen can be made quickly and easily.

In another aspect of the invention, there is provided a cylindrical screen for a horizontal or inclined well having a multiple welded wedge-wire structure comprising: a perforated base pipe formed with a plurality of fluid collection holes; a plurality of support members extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen on the outside of the perforated base pipe; a spiral wedge-wire wound about the outside surface of the support members so as to form a slit of a predetermined width; and a plurahy of linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction on the outside surface of the spiral wedge -wire so as to form shts of a predetermined width, said linear wedge-wires being welded directly to the spiral wedge-wire.

In another aspect of the invention, a filter member such as a wire-mesh or a filter cloth is interposed between the perforated base pipe and the support members.

According to this aspect of the invention, by selecting a proper filter member so that invasion of sand grains having the minimum grain diameter in sand grains of the oil stratum can be prevented by the filter member, the width of the sht of the wedge-wire can be made a width which can prevent invasion of sand grains of a larger grain diameter and, as a result, quantity of oil flowing into the screen can be made larger while preventing invasion of sand grains. Further, since a wedge-wire of a larger diameter can be used by selecting a larger sht width, mechanical strength of the cylindrical screen can be improved to that degree.

In still another aspect of the invention, there is provided a cylindrical screen for a horizontal or inclined well having a multiple welded wedge-wire structure comprising: a perforated base pipe formed with a plurality of fluid collection holes; a plurality of support members extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen on the outside of the perforated base pipe; a spiral wedge-wire wound about the outside surface of the support members so as to form a sht of a predetermined width; and a plurahy of linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form shts of a predetermined width, said linear wedge-wires being arranged with a predetermined interval in the radial direction of the screen from the outside surface of the spiral wedge-wire and thereby defining an annulus between the spiral wedge-wire and the linear wedge-wires; an outer spiral wedge-wire wound on the outside of the linear wedge-wires so as to form a sht of a predetermined width and being welded directly to the hnear wedge-wires, said spiral wedge-wire and said linear wedge-wires being arranged in such a manner that their flat surfaces face each other, and gravel being packed in the annulus between the spiral wedge- wire and the linear-wedge-wires. According to this aspect of the invention, since the spiral wedge-wire and the linear wedge-wires are arranged in such a manner that the flat surfaces of the spiral wedge-wire and the linear wedge-wires face each other, gravel can be packed smoothly in the annulus between the sprial wedge wire and the linear wedge-wires and, as a result, there is no likelihood of occurrence of a void where gravel is not filled so that a perfect gravel packed screen can be produced.

Brief Description of the Drawings

In the accompanying drawings, FIG. 1 is a perspective view showing a preferred embodiment of the invention;

FIG. 2 is a perspective view showing another embodiment of the invention;

FIG. 3 is an enlarged view of a portion of the embodiment shown inFIG. ι;

FIG. 4 is a perspective view showing another embodiment of the invention;

FIG. 5 is a perspective view showing another embodiment of the invention; FIG. 6 is a perspective view showing another embodiment of the invention;

FIG. 7 is a perspective view showing another embodiment of the invention;

FIG. 8 is a perspective view showing another embodiment of the invention;

FIG. 9 is a perspective view showing another embodiment of the invention;

FIG. 10 is a perspective view showing another embodiment of the invention;

FIG. 11 is a perspective view showing a portion of the embodiment shown in FIG. 10;

FIG. 12 is a sectional view schematically showing a horizontal well;

FIG. 13 is a sectional view showing a state of packing of gravel in a vertical well; and

FIGs. 14A and 14B are sectional views showing a state of a screen in a horizontal well.

Best Mode for Carrying Out the Invention Referring now to the drawings, embodiments of the invention will be described.

FIG. 1 shows a preferred embodiment of the cylindrical screen for a horizontal or inclined well having a multiple wire structure made according to the invention and FIG. 3 shows a part of the cylindrical screen in an enlarged scale.

In this embodiment, a cylindrical screen 1 comprises a plurahty of support rods 2 extending in the axial direction of the screen 1 and arranged at a predetermined interval in the circumferential direction of the screen 1, a spiral wedge-wire 3 wound about the outside surface of the support rods 2 so as to form a sht 3a of a predetermined width, and a plurahty of hnear wedge-wires 4 extending in the axial direction of the screen 1 and arranged at a predetermined interval in the circumferential direction on the outside surface of the spiral wedge-wire 3 so as to form shts 4a of a predetermined width. The hnear wedge-wires 4 are welded directly to a flat surface of the spiral wedge- wire 3.

The support rods 2 constitute the support members supporting the spiral wedge-wire 3. In the illustrated example, the support rods 2 are formed of rods made of steel having a circular shape in section but may be formed of rods having another shape in section. The support rods 2 are arranged at a predetermined interval in the circumferential direction of the screen 1, generally in the form of a cylinder.

On the outside surface of the support rods 2 is wound the spiral wedge-wire 3 in the direction substantially crossing the support rods 2. As will be apparent from FIG.3, the spiral wedge wire 3 is arranged in such a manner that its flat surface 3b faces outside and the other two sides 3c an 3d define the sht 3 a with the adjacent wedge -wire portion which widens gradually radially inwardly, i.e., toward the inside of the screen. The spiral wedge-wire 3 is welded at its inside apex 3e to the support rods 2. The width of the sht 3a in the axial direction of the spiral wedge-wire 3 is so set that the width of the sht 3a at the same plane as the outside surface of the spiral wedge-wire 3 will become smaller than the width of the outside surface of the spiral wedge-wire 3.

As shown in FIG. 3, the linear wedge-wires 4 are arranged, like the spiral wedge-wire 3, in such a manner that its flat surface 4b faces outside and the other two sides 4c an 4d define the sht 4a with the adjacent wedge-wires which widens gradually toward the inside of the screen. The linear wedge-wires 4 are welded at their inside apexes 4e to the flat outside surface 3b of the spiral wedge- wire 3. FIG. 2 shows another embodiment of the invention. In the embodiment of FIG. 2 and subsequent embodiments, the same component elements as those of the embodiment of FIG. 1 are designated by the same reference characters and description thereof will be omitted.

The embodiment of FIG. 2 differs from the embodiment of FIG. 1 in the construction that the support members consist of linear wedge-wires 5 extending in the axial direction of the screen 1 and arranged at a predetermined interval in the circumferential direction of the screen 1 so as to form shts 5a of a predetermined width. The linear wedge-wires 5 perform a function of a filter in the screen in addition to the function of the support members supporting the spiral wedge- wire 3. Thus, the embodiment of FIG. 2 is a triple-layer screen while the embodiment of FIG. 1 is a double-layer screen. Accordingly, in the embodiment of FIG. 2, in a case where the outermost hnear wedge- wires 4 and the intermediate spiral wedge-wire 3 have been eroded by the colliding sand grains, the innermost linear wedge-wires 5 can continue to function as a screen and, accordingly, the life of the cylindrical screen can be prolonged as compared with the embodiment of FIG. 1

FIG. 4 shows another embodiment of the invention. The cylindrical screen 20 in this embodiment further comprises an outer spiral wedge- wire 6 wound about the outside surface of the linear wedge-wires 4 of the embodiment of FIG. 1 so as to form a sht 6a of a predetermined width. The outer spiral wedge-wire 6 is welded directly to the flat outside surface 4b of the linear wedge-wires 4. The sht 6a of the outer spiral wedge-wire 6 widens toward the inside of the screen in the same manner as the sht 3a of the spiral wedge-wire 3. This screen is a triple-layer screen and the life of the screen can be prolonged as compared with the embodiment of FIG. 1.

FIG. 5 shows another embodiment of the invention. The cyhndrical screen 30 in this embodiment further comprises an outer spiral wedge-wire 6 wound about the outside surface of the hnear wedge-wires 4 of the embodiment of FIG. 2 so as to form a sht 6a of a predetermined width. The outer spiral wedge-wire 6 is welded directly to the flat outside surface 4b of the hnear wedge-wires 4. The sht 6a of the outer spiral wedge-wire 6 widens toward the inside of the screen in the same manner as the sht 3a of the spiral wedge-wire 3. This screen is a quadruple-layer screen and the life of the screen can be prolonged as compared with the embodiment of FIG. 2.

FIG. 6 shows another embodiment of the invention. The cyhndrical screen 40 of FIG. 6 further comprises a plurahty of outer linear wedge-wires 7 extending in the axial direction of the screen 40 and arranged at a predetermined interval in the circumferential direction of the screen40 so as to form shts 7a of a predetermined width on the outside of the outer spiral wedge-wire 6 of the embodiment of FIG. 4. The outer linear wedge-wires 7 are welded directly to the flat outside surface 6b of the outer spiral wedge-wire 6. The shts 7a of the outer linear wedge-wires 7 widen toward the inside of the screen in the same manner as the shts 4a of the hnear wedge-wires 4. This cylindrical screen 40 is a quadruple-layer screen and the life of the screen can be prolonged as compared with the embodiment of FIG. 4.

FIG. 7 shows another embodiment of the invention. The cyhndrical screen 50 of FIG. 7 further comprises a plurahty of outer linear wedge-wires 7 extending in the axial direction of the screen 50 and arranged at a predetermined interval in the circumferential direction of the screen 50 so as to form shts 7a of a predetermined width on the outside of the outer spiral wedge-wire 6 of the embodiment of FIG. 5. The outer linear wedge-wires 7 are welded directly to the flat outside surface 6b of the outer spiral wedge-wire 6. The shts 7a of the outer linear wedge-wires 7 widen toward the inside of the screen in the same manner as the shts 4a of the hnear wedge-wires 4. This cylindrical screen 50 is a quintuple-layer screen and the life of the screen can be prolonged as compared with the embodiment of FIG. 5.

FIG. 8 shows another embodiment of the invention. In this embodiment, the cylindrical screen 60 comprises a perforated base pipe 8 formed with a plurahty of fluid collection holes 8a, a plurahty of support rods 2 extending in the axial direction of the screen 60 and arranged at a predetermined interval in the circumferential direction of the screen 60 on the outside of the perforated base pipe 8, a spiral wedge-wire 3 wound about the outside surface of the support rods 2 so as to form a sht a of a predetermined width, and a plurahty of hnear wedge-wires 4 extending in the axial direction of the screen 60 and arranged at a predetermined interval in the circumferential direction on the outside surface of the spiral wedge-wire 3 so as to form shts 4a of a predetermined width. The linear wedge-wires 4 are welded directly to the flat surface 3b of the spiral wedge-wire 3. By comprising the perforated base pipe 8, the cylindrical screen 60 can be improved in its strength.

Instead of the support rods 2, the linear wedge-wires 5 may be used as the support member in a similar manner to the embodiment of FIG. 2. FIG. 9 shows another embodiment of the invention. In the cylindrical screen 70 of this embodiment, a wire-mesh 9 which constitutes a filter member is interposed between the perforated base pipe 8 and the support rods 2. A different filter material such as a filter cloth may be used instead of the wire-mesh 9. FIG. 10 shows another embodiment of the invention. In this embodiment, the cylindrical screen 80 comprises a perforated base pipe 8 formed with a plurahty of fluid collection holes 8a, a plurahty of support rods 2 extending in the axial direction of the screen 80 and arranged at a predetermined interval in the circumferential direction of the screen 80 on the outside of the perforated base pipe 8, a spiral wedge-wire 3 wound about the outside surface of the support rods 2 so as to form a sht 3a of a predetermined width, and a plurahty of linear wedge-wires 11 extending in the axial direction of the screen 80 and arranged at a predetermined interval in the circumferential direction of the screen 80 so as to form shts 11a of a _ _Δ

predetermined width. The hnear wedge-wires 11 are arranged with a predetermined interval in the radial direction of the screen 80 from the outside surface of the spiral wedge-wire 3 and thereby define an annulus between the spiral wedge-wire 3 and the hnear wedge-wires 11. An outer spiral wedge-wire 12 is wound on the outside of the linear wedge-wires 11 so as to form a sht 12a of a predetermined width and is welded directly to the outside ridgeline lie of the hnear wedge- wires 11. As will be apparent from FIG. 11 which show the linear wedge-wires 11 and the outer spiral wedge-wire 12 only, the inside of the linear wedge- ires 11 is formed as a flat surface lib. The spiral wedge-wire 3 and the hnear wedge-wires 11 are arranged in such a manner that their flat surfaces 3b and lib face each other, and gravel 13 is packed in the annulus between the spiral wedge-wire 3 and the hnear-wedge-wires 11.

In the above described embodiments, the width of the shts of the respective wires constituting the multiple layered cylindrical screens is set at a proper value within the range from 0.1mm to 0.3mm suitable for achieving the object of the cyhndrical screens.

Industrial Applicability The cylindrical screen of the present invention can be utilized as a well screen for a horizontal or inclined well, particularly a well screen for a horizontal or inclined oil well. The invention is capable of coping with erosion of a screen wire caused by collision of sand grains accompanying crude oil flowing into the well with the screen wire and thereby prolonging the life of the cyhndrical screen.

Claims

1. A cylindrical screen for a horizontal or inclined well having a multiple welded wedge-wire structure comprising: a plurahty of support members extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen; a spiral wedge-wire wound about the outside surface of the support members so as to form a sht of a predetermined width; and a plurahty of linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction on the outside surface of the spiral wedge -wire so as to form shts of a predetermined width, said linear wedge-wires being welded directly to the spiral wedge-wire.

2. A cylindrical screen as defined in claim 1 wherein said support members are support rods.

3. A cylindrical screen as defined in claim 1 wherein said support members are linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form shts of a predetermined width.

4. A cyhndrical screen as defined in claim 1 further comprising an outer spiral wedge-wire wound about the outside surface of the hnear wedge-wires so as to form a sht of a predetermined width, said outer spiral wedge-wire being welded directly to the hnear wedge-wires.

5. A cylindrical screen as defined in claim 4 wherein said support members are support rods.

6. A cyhndrical screen as defined in claim 4 wherein said support members are hnear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form shts of a predetermined width.

7. A cylindrical scren as defined in claim 4 further comprising a plurahty of outer linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form shts of a predtermined width, said outer linear wedge-wires being welded directly to the outer spiral wedge-wire.

8. A cylindrical screen as defined in claim 7 wherein said support members are support rods.

9. A cylindrical screen as defined in claim 7 wherein said support members are linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form shts of a predetermined width.

10. A cylindrical screen for a horizontal or inclined well having a multiple welded wedge-wire structure comprising: a perforated base pipe formed with a plurahty of fluid collection holes; a plurahty of support members extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen on the outside of the perforated base pipe; a spiral wedge-wire wound about the outside surface of the support members so as to form a sht of a predetermined width; and a plurahy of linear wedge-wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction on the outside surface of the spiral wedge-wire so as to form shts of a predetermined width, said linear wedge-wires being welded directly to the spiral wedge -wire.

11. A cylindrical screen as defined in claim 10 wherein a filter member is interposed between the perforated base pipe and the support members.

12. A cylindrical screen for a horizontal or inclined well having a multiple welded wedge-wire structure comprising: a perforated base pipe formed with a plurahty of fluid collection holes; a plurahty of support members extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen on the outside of the perforated base pipe; a spiral wedge-wire wound about the outside surface of the support members so as to form a sht of a predetermined width; and a plurahy of linear wedge -wires extending in the axial direction of the screen and arranged at a predetermined interval in the circumferential direction of the screen so as to form shts of a predetermined width, said linear wedge-wires being arranged with a predetermined interval in the radial direction of the screen from the outside surface of the spiral wedge-wire and thereby defining an annulus between the spiral wedge-wire and the linear wedge-wires; an outer spiral wedge-wire wound on the outside of the linear wedge-wires so as to form a sht of a predetermined width and being welded directly to the hnear wedge-wires, said spiral wedge-wire and said hnear wedge-wires being arranged in such a manner that their flat surfaces face each other, and gravel being packed in the annulus between the spiral wedge- wire and the hnear-wedge-wires.