WO2004035231A1

WO2004035231A1 - A screen for a vibratory separator

Info

Publication number: WO2004035231A1
Application number: PCT/EP2003/050153
Authority: WO
Inventors: George Alexander Burnett
Original assignee: Varco I/P, Inc.
Priority date: 2002-10-17
Filing date: 2003-05-07
Publication date: 2004-04-29
Also published as: GB0224153D0; AU2003240839A1; GB2394195A

Abstract

A screen for a vibratory separator, said screen comprising at least one layer of mesh adhered to a panel (1), said panel (1) having at least one aperture (5) with at least one edge (28a, 29a, 30a) bounding said aperture (5), said at least one layer of mesh overlying said at least one aperture (5) characterised in that a portion (28, 29, 30) of said panel (1) is folded to form said edge (28a,29a,30a) of said aperture.

Description

A SCREEN FOR A VIBRATORY SEPARATOR The present invention relates to a screen for a vibratory separator, a shale shaker comprising the screen and a panel for a screen. In the drilling of a borehole in the construction of an oil or gas well, a drill bit is arranged on the end of a drill string and is rotated to bore the borehole . A drilling fluid known as "drilling mud" is pumped through the drill string to the drill bit to lubricate the drill bit. The drilling mud is also used to carry the cuttings produced by the drill bit and other solids to the surface through an annulus formed between the drill string and the borehole . The drilling mud contains expensive synthetic oil-based lubricants and it is normal therefore to recover and re-use the used drilling mud, but this requires the solids, to be removed from the drilling mud. This is achieved by processing the drilling fluid. The first part of the process is to separate the solids from the solids laden drilling mud. This is at least partly achieved with a shale shaker, such as those disclosed in US 5,265,730, WO 96/33792 and WO 98/16328.

Shale shakers generally comprise an open bottomed basket having one open discharge end and a solid walled feed end. A number of rectangular screens are arranged in the basket, which are held in C-channel rails located on the basket walls , such as those disclosed in GB-A- 2,176,424. The basket is arranged on springs above a receptor for receiving recovered drilling mud. A skip or ditch is provided beneath the open discharge end of the basket. A motor is fixed to the basket, which has a drive rotor provided with an offset clump weight. In use, the motor rotates the rotor and the offset clump weight, which causes the basket and the screens fixed thereto to shake. Solids laden mud is introduced at the feed end of the basket on to the screens . The shaking motion induces the solids to move along the screens towards the open discharge end. The recovered drilling mud is received in the receptor for further processing and the solids pass over the discharge end of the basket into the ditch or skip .

The screens are generally of one of two types : hook- strip; and pre-tensioned.

The hook-strip type of screen comprises several rectangular layers of mesh in a sandwich, usually comprising one or two layers of fine grade mesh and a supporting mesh having larger mesh holes and heavier gauge wire. The layers of mesh are joined at each side edge by a strip which is in the form of an elongate hook. In use, the elongate hook is hooked on to a tensioning device arranged along each side of a shale shaker. The shale shaker further comprises a crowned set of supporting members, which run along the length of the basket of the shaker, over which the layers of mesh are tensioned. An example of this type of screen is disclosed in GB-A-1,526,663. The supporting mesh may be provided with or replaced by a panel having apertures therein.

The pre-tensioned type of screen comprises several rectangular layers of mesh, usually comprising one or two layers of fine grade mesh and a supporting mesh having larger mesh holes and heavier gauge wire. The layers of mesh are pre-tensioned on a rigid support comprising a rectangular angle iron frame and adhered thereto. The screen is then inserted into C-channel rails arranged in a basket of a shale shaker. An example of this type of screen is disclosed in GB-A-1,578,948.

A further example of a known rigid support is disclosed in WO 01/76719, which discloses, amongst other things, a flat panel like portion having apertures therein and wing portions which are folded to form a support structure, which may be made from a single sheet of material. This rigid support has been assigned the Trade Mark "UNIBODY" by the applicants.

European Patent Publication Number 1 002 588, discloses a panel comprising a plurality of groups of perforations, each group comprising six generally equally triangular apertures arranged with their apices facing a central portion, wherein the apices of two opposing ones of said triangular apertures are spaced apart further than the apices of opposed ones of the remaining triangular apertures .

The layers of mesh in the screens wears out frequently and therefore needs to be easily replaceable. Shale shakers are generally in the order of 5ft wide and 10ft long. A screen of dimensions 5ft wide by 10ft long is difficult to handle, replace and transport. It is known to use two, three, four or more screens in a single shale shaker. A standard size of screen currently used is of the order of 5ft by 4ft.

The present invention attempts to provide a screen which is rigid and light weight.

The present invention also attempts to provide a screen which will increase the life of layers of screening material arranged thereon.

The present invention also attempts to provide a panel for a screen which only blinds a small proportion of the area of the layers of screening material arranged thereon.

The present invention also attempts to retain rigidity in the screen at its interface with another screen or the end fitting arrange in the basket of the shale shaker.

According to a first aspect of the present invention, there is provided a screen for a vibratory separator, said screen comprising at least one layer of mesh adhered to a panel, said panel having at least one aperture with at least one edge bounding said aperture, said at least one layer of mesh overlying said at least one aperture characterised in that a portion of said panel is folded to form said edge of said aperture. Preferably, the aperture is bounded by a second edge wherein a second portion of the panel is folded to form the second edge. Advantageously, a first end of the edge meets a first end of the second edge, further comprising an interlinking portion arranged between a first end of the portion and a first end of the second portion, which interlinking portion is folded to form a corner of the aperture. Preferably, the interlinking portion is integral with the first and second portions .

Preferably, the aperture is bounded by a third edge to form a triangular aperture, wherein a third portion of the panel is folded to form the third edge . Advantageously, a first end of the edge meets a first end of the second edge, and an interlinking portion is arranged between a first end of the portion and a first end of the second portion; a first end of the third edge meets a second end of the edge and an interlinking portion is arranged between a first end of a third portion and a second end of the portion and a second end of the second edge meets a second end of the third edge and an interlinking portion is arranged between a second end of the third portion and a second end of the second portion, wherein the interlinking portions are folded to form three corner of the triangular aperture . Advantageously, the interlinking portions are integral with the first, second portions and third portions.

Preferably, the portions of adjacent apertures form a channel .

Advantageously, the panel comprises a plurality of apertures arranged in rows. Preferably, the portions of adjacent apertures in adjacent rows form a continuous channel .

Preferably, the panel is rectangular. Advantageously, the panel comprises folded wing portions . The folded wing portions may be used to increase the rigidity of the panel and may be used to locate the panel on a reinforcing panel .

The first aspect of the present invention also provides a screen support comprising a panel of the invention and a reinforcing panel. Preferably, the reinforcing panel comprises at least one structural support portions abutting the panel .

The first aspect of the present invention also provides a screen comprising a panel of the invention and at least one layer of screening material arranged thereon .

The first aspect of the present invention also provides a shale shaker comprising a screen as claimed of the invention, a basket and a shaking mechanism.

The first aspect of the present invention also provides a method of making an aperture in a panel for a screen comprising the steps of punching or cutting an opening in the panel and using a form tool to fold portions surrounding the opening to form edges of said aperture . * * *

According to a second aspect of the present invention, there is provided a screen support comprising a panel having a plurality of apertures , each aperture having at least one vertex, the vertices of adjacent apertures pointing towards a point characterised in that an opening in said panel is located at said point.

Preferably, the opening is circular, although the opening may be triangular, square, pentagonal, hexagonal, heptagonal or octagonal. Advantageously, the opening is smaller has an open area smaller than that of an aperture, preferably smaller than half the area and most preferably smaller than a third the area of an aperture .

Advantageously, the apertures are triangular apertures, although the apertures may be diamond shaped, square , pentagonal , hexagonal , heptagonal or octagonal . The triangular apertures

According to the second aspect of the present invention, there is also provided a screen support comprising a panel having a plurality of adjacent apertures , each aperture having a first shape and a first area and an area of panel therebetween, characterised in that an opening of a second shape and a second area is located in the area of panel therebetween.

According to the second aspect of the invention, there is also provided a panel comprising a plurality of groups of perforations , each group comprising six generally equally triangular apertures arranged with their apices facing a central portion, wherein the apices of two opposing ones of said triangular apertures are spaced apart further than the apices of opposed ones of the remaining triangular apertures characterised in that said central portion has an opening therein.

For a better understanding of the present invention, reference will now be made, by way of example to the accompanying drawings, in which:

Figure 1 is a top plan view of a panel of a screen support in accordance with the present invention;

Figure 2 is an enlarged top view of part of the panel shown in Figure 1 ;

Figure 3 is top plan view of a blank used in the construction of a panel in accordance with the present invention;

Figure 4 is a template used in the construction of the panel of the present invention;

Figure 5 is a side cross-sectional broken view of two screen supports in accordance with the present invention; and

Figure 6 is a top plan view of a blank used in the construction of a reinforcing panel of the screen support in accordance with the invention.

Referring to Figure 1 there is shown a panel 1 for a screen. The panel 1 is made from a 1.5mm mild steel plate. The panel 1 comprises an area 2 provided with a plurality of apertures, a left side portion 3 provided with no apertures and a right side portion 4 provided with no apertures . The plurality of apertures in area 2 comprises a plurality of triangular apertures and a plurality of circular openings . One of the triangular apertures is identified by reference numeral 5 and one of the circular openings is identified by reference numeral

6. The triangular apertures are substantially equilateral, having three congruent sides. The congruent sides may be between 5cm and 15cm long, preferably 6cm to

12cm and most preferably 8cm. The area of the opening may be between 10 square centimetres and 100 square centimetres, preferably 20 square centimetres to 60 square centimetres and most preferably 30 square centimetres . The apertures may be of any shape , preferably having an area of between 10 square centimetres and 100 square centimetres, preferably 20 square centimetres to 60 square centimetres and most preferably 30 square centimetres.

The panel 1 is formed from a blank shown in Figure 3. Lines 7 and 8 and fold lines 9 and 10 indicate the boundary of area 2 which will be provided with the plurality of apertures . The area 2 , the left side portion 3 and right side portion 4 , all lie in the same plane to form a flat top surface . Left side portion 3 and right side portion 4 extend the entire length of the panel 1. Wing portions 11 and 12 approximately 1cm wide extend the entire length of the panel 1. The wing portions 11 and 12 are folded downwardly to stand approximately at right angles to the top surface . The forward end of the panel 1 has a forward end portion 13 extending the width of the panel 1 and is folded downwardly along fold line 9 to be perpendicular to the top surface of the panel 1 to form an end face of a screen interface . The forward end portion 13 has a further portion 14 folded along line 15, projecting forwardly. The trailing end of the panel 1 has a rear end portion 16 folded downwardly along fold line 10, such that the rear end portion 16 lies at perpendicularly to the top surface of the panel 1. The folded wing portions 11 and 12 and the folded end portions 13 and 16 meet at their respective edges, at which they may be welded together, soldered or otherwise joined. The area 2 of the blank shown in Figure 3 has a plurality of apertures including a plurality of triangular apertures and a plurality of circular apertures to be formed therein. The triangular aperture 5 is formed by first punching, laser cutting, sawing, drilling, milling or casting the blank with an opening 17 , in the shape shown in the template shown in Figure 4. The shape comprises three semi circular ends 18, 19 and 20 each arranged within and close to where a respective vertex 21, 22 and 23 of the triangular aperture 5 is to be formed, as shown in Figure 2. A small triangular opening 24 is punched, laser cut, sawn, drilled, milled or cast concentric with the triangular aperture 5 to be formed and slots 25, 26 and 27 link the semi circular ends 18, 19 and 20 to form structural portions 28, 29 and 30. The structural portions 28, 29 and 30 are folded downwardly along fold line 31 , over a form tool (not shown) having a similar profile to the fold line 31. The structural portions and 28, 29 and 30 are folded by the form tool to an angle of approximately 65° to the surface of the panel 1 to form edges 28a, 29a and 30a. The areas of panel bounding the semi circular ends 32 , 33 and 34 are also folded downwardly.

Referring back to Figures 1 and 2 , triangular apertures , such as triangular aperture 5 , are arranged in ten sets of rows in the panel 1. A first set 35 comprises a first row 36 having a rearwardly pointing triangular aperture 5 and a forwardly pointing triangular aperture 37 adjacent thereto, such that folded structural portion 29 and a folded structural portion 38 of the forwardly pointing triangular aperture 37 form a rib 39 approximately 2.3mm wide. An apex 40 of the forwardly pointing triangular aperture 37 is rearwardly offset by approximately 2.3mm?? from a base 41 of the rearwardly pointing triangular aperture 5. The first row 36 comprises twelve forwardly pointing triangular apertures interspaced by twelve rearwardly pointing triangular apertures . The first set 35 also comprises a second row 42 , which is a mirror image of the first row 35 about line A-A. A structural portion 44 of forwardly pointing triangular aperture 37 of the first row 36 and a structural portion 45 of rearwardly pointing triangular aperture 46 of the second row 42, form a rib 47. The rib 47 is in line with ribs 48 to 58 in the first set 35. A circular opening 59 is drilled, punched, laser cut or otherwise formed in the panel 1 between vertices 22, 60, 61 and 62 of rearward pointing triangular aperture 5, forward pointing triangular aperture 63 , forward pointing triangular aperture 37 and rearward pointing triangular aperture 46 respectively. A segment opening 64 arranged between rearward pointing triangular aperture 5, forward pointing triangular aperture 63 and circular hole 59 is punched, laser cut or otherwise formed in the panel 1, having a straight portion following line 7 of the blank, shown in Figure 3 and a curved portion extending toward the rearward pointing triangular aperture 5 , forward pointing triangular aperture 63 and circular opening 59.

Similarly, circular opening 65 is drilled, punched, laser cut or otherwise formed in the panel 1 between vertices 66, 67, 68, 69, 70 and 71 of forward pointing triangular aperture 37 , rearward pointing triangular aperture 72, forward pointing triangular aperture 73, rearward pointing triangular aperture 74, forward pointing triangular aperture 75, and rearward pointing triangular aperture 46 respectively. The panel 1 may be arranged on a reinforcing panel 100. The reinforcing panel 100 is formed from a blank, which is shown in Figure 6. The blank is made from a 1.5mm mild steel plate. The reinforcing panel 100 has five openings 101 therein. Each opening 101 has been punched, laser cut, sawn, drilled, milled or cast into the blank having a central oblong opening 102 and slots 103 approximately 4cm long extending longitudinally at each end of the central oblong opening 102 to form ten structural support portions 104, which are folded upwardly along fold lines 105 to stand approximately at right angles to the surface of the reinforcing panel 100. The reinforcing panel 100 has a left side portion 106 and a right side portion 107. The lef and right side portions 106 and 107 extend the entire length of the reinforcing panel 100 and are not provided with openings. Wing portions 108 and 109 approximately 4cm wide extend the entire length of the reinforcing panel 100. The wing portions 108 and 109 are folded upwardly along lines 110 and 111 respectively to stand approximately at right angles to the surface of the reinforcing panel 100. The forward end of the reinforcing panel 100 has a forward end portion 112 extending the width of the reinforcing panel 100 and from the reinforcing panel 100 to form a lap of the screen interface. A further portion 113 is folded upwardly along line 114. The trailing end of the reinforcing panel 100 has a rear end portion 115 folded upwardly along fold line 116, such that the rear end portion 115 lies at approximately right angles to the surface of the reinforcing panel 100. The further portion 117 is folded outwardly from the reinforcing panel to an angle of approximately 10° upwardly from the plane in which the reinforcing panel 100 lies. A final portion 118 extends vertically to a level in the same plane as the tops of the structural support portions 104, approximately 4cm from the surface of the reinforcing panel 100. The folded wing portions 108 and 109 and the folded end portion 115 meet at their respective edges , at which they may be welded together, soldered or otherwise joined. A further opening 119 is located at the rearward end of the reinforcing panel .

The downwardly folded wings 11 and 12 of the panel 1 are located over the upwardly folded wings 108 and 109 of the reinforcing panel 100 and welded together. Each of the ten structural supporting members 104 of the reinforcing panel 100 are located in every other of the twenty perpendicular channels 120 of the panel 1 formed by the structural portions of the triangular apertures and welded therein. The rear end portion 16 locates over final portion 118 and welded thereto. A sealing member 200 comprises an elongate rubber butyl or synthetic rubber having, in section, a square base 201 and two part circular seal members 202 and 203 lying adjacent one another forming a gully 204. The part circular seal members 202 and 203 are arranged on an upper part of the square base 201 and are adhered or integral with one another. The square base 201 of the sealing member 200 is located on the forward end portion 112 of the reinforcing member 100 and on a forward side of the seal by the further portion 113 of the reinforcing member 100. The further portion 14 of the panel 1 embeds itself into the square base of the sealing member 200, which may have a slot therein for receiving the further portion 14. The sealing member extends across the entire width of the screen support. Layers of mesh, not shown, are laid on top of the panel 1 over the apertures and adhered to the panel at the side portions 3 and 4 and along ribs bounding the triangular apertures and the circular holes to form a screen. Three layers of mesh may be adhered to the panel, one on top of the other, the top two layers of a fine grade mesh and a bottom, supporting layer of mesh having larger openings and comprising larger diameter wires making up the mesh. The layers of mesh may be adhered to the panel using a powder, which is activated by heat to bond the layers of mesh to the panel.

In use, the screen support is inserted into a shale shaker (not shown) . Drilling mud having solids entrained therein is introduced at a feed end of the shale shaker and is shaken along the layers of mesh on the screen. Fluid and small particles pass through the layers of mesh on the screen and through the triangular apertures and the circular openings in the panel 1 and through the openings 102, 119 in the reinforcing panel and into a receiver (not shown) . The larger solids pass over the layers of screening material and out of a discharge end of the shale shaker into a skip or ditch.

The reinforcing panel may be of the type that is fully described in co-pending application entitled "Screen Support" filed with even date. The interface provided between adjacent screens and with a fitting in the shale shaker may be of the type that is fully described in co-pending application entitled "Screen Support" also filed with even date .

The apertures in the panel are preferably of a size which does not necessitate the need for a layer of strips or straps between the panel and the layers of mesh. Most preferably, the apertures are of such a size that there is also no need for a supporting mesh supporting the layers of mesh, the supporting mesh having larger openings and having larger wires making up the mesh that that of the layers of mesh.

Claims

1. A screen for a vibratory separator, said screen comprising at least one layer of mesh adhered to a panel

(1) , said panel (1) having at least one aperture (5) with at least one edge (28a, 29a, 30a) bounding said aperture

(5) , said at least one layer of mesh overlying said at least one aperture (5) characterised in that a portion

(28,29,30) of said panel (1) is folded to form said edge

(28a, 29a, 30a) of said aperture.

2. A screen as claimed in Claim 1, wherein said aperture (5) is bounded by a second edge (28a, 29a, 30a) wherein a second portion (28,29,30) of said panel (1) is folded to form said second edge (28a, 29a, 30a) .

3. A screen as claimed in Claim 2 , wherein a first end of said edge (28a, 29a, 30a) meets a first end of said second edge (28a, 29a, 30a) , further comprising an interlinking portion (32,33,34) arranged between a first end of said portion (28,29,30) and a first end of said second portion (28,29,30), which interlinking portion (32,33,34) is folded to form a corner of said aperture.

4. A screen as claimed in Claim 3 , wherein said interlinking portion (32,33,34) is integral with said first (28,29,30) and second portions (28,29,30).

5. A screen as claimed in Claim 2 , 3 or 4 , wherein said aperture (5) is bounded by a third edge (28a, 29a, 30a) to form a triangular aperture, wherein a third portion (28,29,30) of said panel (1) is folded to form said third edge (28a, 29a, 30a) .

6. A screen as claimed in Claim 5, wherein: a first end of said edge (28a, 29a, 30a) meets a first end of said second edge (28a, 29a, 30a) , and an interlinking portion (32,33,34) is arranged between a first end of said portion (28,29,30) and a first end of said second portion (28,29,30); a first end of said third edge (28a, 29a, 30a) meets a second end of said edge (28a, 29a, 30a) and an interlinking portion (32,33,34) is arranged between a first end of a third portion and a second end of said portion (28,29,30) and a second end of said second edge (28a, 29a, 30a) meets a second end of said third edge (28a, 29a, 30a) and an interlinking portion (28a, 29a, 30a) is arranged between a second end of said third portion (28,29,30) and a second end of said second portion (28,29,30) , wherein said interlinking portions (32,33,34) are folded to form three corner of said triangular aperture .

7. A screen as claimed in Claim 6, wherein said interlinking portions (32,33,34) are integral with said first (28,29,30), second portions (28,29,30) and third portions (28,29,30) .

8. A screen as claimed in any preceding claim, wherein said portions (28,29,30) of adjacent apertures (5,37) form a channel .

9. A screen as claimed in any preceding claim, comprising a plurality of apertures (5) arranged in rows

(36,42).

10. A screen as claimed in Claim 8 and 9, wherein said portions (28,29,30) of adjacent apertures (37,46) in adjacent rows (36,42) form a continuous channel (120) .

11. A screen as claimed in any preceding claim, wherein said panel (1) is rectangular.

12. A screen as claimed in any preceding claim wherein said panel (1) has folded wing portions (11,12) .

13. A screen comprising a panel as claimed in any preceding claim and a reinforcing panel (100) .

14. A screen as claimed in Claim 13, wherein said reinforcing panel (100) comprises at least one structural support portions (104) abutting said panel.

15. A screen comprising a panel as claimed in any of claims 1 to 12 and three layer of mesh arranged thereon.

16. A shale shaker comprising a screen as claimed in any preceding claim, a basket and a shaking mechanism.

17. A method of making a panel for a screen comprising the steps of punching or cutting an opening in said panel and using a form tool to fold portions surrounding said opening to form edges of an aperture .

* * *

18. A panel for a screen, said panel having a plurality of apertures (5) , each aperture (5) having at least one vertex, the vertices of adjacent apertures pointing towards a point characterised in that an opening (59,65) in said panel is located at said point.

19. A panel as claimed in Claim 18, wherein said opening (59,65) has a shape comprising one of a: circle, triangle, square, pentagon, hexagon, heptagon or octagon.

20. A panel as claimed in Claim 18 or 19, wherein said opening (59,65) has an open area smaller than that of said aperture (5) , preferably smaller than half the area and most preferably smaller than a third the area of an aperture.

21. Advantageously, the apertures are triangular apertures, although the apertures may be diamond shaped, square, pentagonal , hexagonal , heptagonal or octagonal .

22. A screen support comprising a panel having a plurality of adjacent apertures, each aperture having a first shape and a first area and an area of panel therebetween, characterised in that an opening of a second shape and a second area is located in the area of panel therebetween.

23. A panel comprising a plurality of groups of perforations, each group comprising six generally equally triangular apertures arranged with their apices facing a central portion, wherein the apices of two opposing ones of said triangular apertures are spaced apart further than the apices of opposed ones of the remaining triangular apertures characterised in that said central portion has an opening therein.