A METHOD FOR MAKING A SCREEN FOR A SHALE SHAKER The present invention relates to a method for making a screen for a shale shaker and a screen for a shale shaker . Vibratory separators are used in a wide variety of industries to separate materials such as liquids from solids or solids from solids . 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 vibratory separator, such as those shale shakers 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. Drilling mud passes through the screens. 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-I ,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-I ,578 , 948.

A further example of a known rigid support is disclosed in PCT Publication No. 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.

Shale shakers are generally in the order of Im to 2m wide and 2m to 4m long. A screen to fit the footprint of the shale shaker 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 1.2m by Im.

In a variety of prior art screens , screen mesh or screen cloth as manufactured has a plurality of initially substantially square or rectangular openings defined by intersecting wires of the screen; i.e., as made a first plurality of substantially parallel wires extending in one general direction are perpendicular to a second plurality of substantially parallel wires, all the wires defining square or rectangular openings . In placing one such screen mesh or cloth on top of another, it can happen accidentally that wires of one layer are aligned with wires of another layer; but no effort is made to insure that a large portion, a majority, or substantially all wires of one layer are aligned with wires of another layer. In many actual uses, misalignment of wires occurs, resulting in the deformation of desired openings between wires and, therefore, in reduced screen effectiveness, reduced efficiency, and premature screen failure . The present invention provides a method for making a screen for a shale shaker, the screen comprising a first layer and second layer of screening material, the first layer having a series of shute wires and a series of warp

wires , the second screen having a series of shute wires and a series of warp wires , the method comprising the steps of selecting the first and second layers by wire count ratio, and combining a panel and a support with the at least first and second layers of screening material, the panel having multiple spaced-apart openings, at least a portion of which having a central cross-member extending from a first side of an opening to a second side thereof. Preferably, said plurality of openings in a pattern on the panel as viewed from above. Advantageously, the pattern covers at least one area which is subjected to high impact in use. Preferably, the at least one area is located at at least one of: at one end of the screen at a feed end of the screen; a central area of the screen adjacent the feed end; and at two side areas of the screen each adjacent the feed end. Preferably, where, in use, solids laden drilling mud is fed on to the screen.

Advantageously, the step of selecting the first and second layers by count ratio provides alignment of a number of the warp wires of the first layer with a number of warp wires wires of the second layer and alignment of a number of shute wires of the first layer with a number of shute wires of the second layer. Preferably, the method further comprises the step of combining a the at least two layers of screening material with a third layer of screening material, the third layer having a series of warp wires , the method further comprising the step of selecting the third layer by wire count ratio to obtain alignment of a number of the warp wires of the third layer with a number of warp wires wires of the first and/or second layer.

Advantageously, the multiple spaced-apart openings

include a plurality of openings with a regular hexagonal shape. Preferably, a side-to-side length across one of the regular hexagonal openings is 46πun (1.83 inches).

Preferably, the plurality of the multiple spaced- apart openings includes a plurality of openings with an elongated hexagonal shape. Advantageously, a side-to-side length across one of the elongated hexagonal openings is

56mm (2.19 inches).

Advantageously, the support is a frame. Preferably, the support has two spaced-apart ends, each of the two spaced-apart ends having a shaped edge, the shaped edge having a shape corresponding to a shape of a portion of the multiple spaced-apart openings. Advantageously, the shaped edges block flow through the at least two layers of screening material .

The present invention also provides a screen for a shale shaker, the screen comprising a first layer and second layer of screening material, the first layer having a series of shute wires and a series of warp wires, the second screen having a series of shute wires and a series of warp wires, the first and second layers selected by wire count ratio, and combined a panel and a support, the panel having multiple spaced-apart openings, at least a portion of which having a central cross-member extending from a first side of an opening to a second side thereof.

The present invention also relates to a screen for a vibratory separator, the screen comprising at least two layers of screening material, the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires, the second layer made of a plurality of intersecting second wires, the first layer

above the second layer, the first layer having a warp- to-shute wire count ratio A between 0.9 and 1.1, a wire count ratio B in a first direction between the first layer and the second layer is between 1 to 1.25 and 1 to 1.75, and a wire count ratio C in a second direction different than the first direction between the top layer and the second layer is between 2.25 and 2.75.

Preferably, the ratio A is 1:1, the ratio B is 1:1.5, and the ratio C is 2.5. Advantageously, wires in the first layer range in diameter in inches between .0011 and .0055, wires in the second layer range in diameter in inches between .0011 and .0055, and a ratio of diameters of wires of the first layer to diameters of wires in the second layer ranges between 0.72 and 0.68. Preferably, the first layer and the second layer are calendared together .

The present invention discloses , in certain aspects , screening assemblies for shale shakers or other vibratory separators which have a plurality of screen wires in each of multiple screen mesh and/or screen cloth layers which are substantially aligned - wires in one layer aligned with wires in another layer according to preselected parameters . In certain aspects wires in such screening assemblies remain aligned during use. The present invention discloses , in certain aspects , a screen for a vibratory separator, or shale shaker, having at least two layers of screening material; the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires, the second layer made of a plurality of intersecting second wires, the first layer above the second layer; the first wires including first shute wires and first warp wires, each of the first shute

wires at an angle to first warp wires; the second wires including second shute wires and second warp wires , each of the second shute wires at an angle to second warp wires; each of a plurality of the first warp wires aligned with a corresponding second warp wire according to a preselected wire count ratio, and each of a plurality of the first shute wires aligned with a corresponding second shute wire according to a preselected wire count ratio . In certain particular aspects , wire alignment in such screen assemblies with multiple screening layers is facilitated by using screen meshes or cloths with a selected number of wires per inch in each layer, particularly with a ratio of number of wires in adjacent layers which is a ratio of two numbers which are either exact integers or are almost exact integers; e.g., in certain aspects, within ± 0.1 of an integer.

In other aspects of screen assemblies in accordance with the present invention, wires are aligned either one on top of the other vertically or wires are aligned in a line at an angle to the horizontal plane of a screen assembly; and, in one particular aspect, wires in multiple screen layers are aligned along a line which is coincident with a force vector imparted to the screen assembly by vibrating apparatus of the shaker or separator .

In certain particular aspects , in methods for making a multi-layer screen in accordance with the present invention, multiple layers are carefully stacked together so that wires in different layers are aligned and then, optionally, the layers are connected together (welded, glued, epoxied, adhered, sintered, etc.) to maintain this alignment in subsequent manufacturing steps.

A vibratory separator or shale shaker, in one embodiment in accordance with the present invention is , in accordance with the present invention, provided with one, two, three or more screens as described herein in accordance with the present invention. The present invention, in certain embodiments, includes a vibratory separator or shale shaker with a base or frame; a "basket" or screen mounting apparatus on or in the base or frame; one, two, three or more screens in accordance with the present invention with wires aligned in accordance with the present invention; vibrating apparatus; and a collection tank or receptacle. In one particular aspect, such a shale shaker treats drilling fluid contaminated with solids, e.g. cuttings, debris, etc.

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

Figure IA is a schematic side view in cross-section of part of a screen in accordance with the present invention;

Figure IB is a top view of the part of the screen shown in Figure IA, showing three wires;

Figure 1C is a schematic side cross-section view of part of a screen in accordance with the present invention;

Figure ID is a schematic side cross-section view of a screen (shown partially) in accordance with the present invention . Figure IE is a view in cross-section of part of a screen in accordance with the present invention;

Figure IF is a view in cross-section of the screen shown in Figure IE at an angle to the view of Figure IE;

Figure 2A is a schematic side view in cross-section of part of a screen in accordance with the present invention;

Figure 2B is a top view of part of the screen shown in Figure 2A showing three wires ;

Figure 2C is a schematic view of part of a screen in accordance with the present invention;

Figure 2D is a schematic view of part of a screen in accordance with the present invention;

Figure 3A is a top view of a screen in accordance with the present invention; Figure 3B is an enlarged top view of part of the screen shown in Figure 3A;

Figure 3C is an enlarged top view of the centre of the screen shown in Figure 3A;

Figure 3D is a view in cross-section taken along line 3D-3D of Figure 3A; .

Figure 3E is a view in cross-section taken along line 3E-3E of Figure 3A; Figure 3F is a top view of a top layer of the screen shown in Figure 3A;

Figure 3G is an end view in cross-section of the layer shown in Figure 3F ;

Figure 3H is a top view of a middle layer of the screen of Figure 3A;

Figure 31 is an end view in cross-section of the layer shown in Figure 3H ;

Figure 3J is a side view in cross-section of the layer shown in Figure 3H ; Figure 3K is a top view of a bottom layer of the screen shown in f Figure 3A.

Figure 3L is an end view in cross -section of the layer shown in Figure 3K;

Figure 4A is a top view of a screen in accordance with the present invention comprising an upper layer, a middle layer and a bottom layer;

Figure 4B is an enlarged top view of part of the screen shown in Figure 4A;

Figure 4C is an enlarged top view of the centre of the screen shown in Figure 4A;

Figure 4D is a view in cross-section taken along line 4D-4D of Figure 4A;

Figure 4E is a view in cross-section taken along line 4E-4E of Figure 4A; Figure 4F is a top view of the top layer of the screen shown in Figure 4A;

Figure 4G is an end view in cross-section of the layer shown in Figure 4F;

Figure 4H is a top view of the middle layer of the screen shown in Figure 4A;

Figure 41 is an end view in cross-section of the layer shown in Figure 4H; Figure 4J is a side view in cross-section of the layer shown in Figure 4H;

Figure 4K is a top view of the bottom layer of the screen shown in Figure 4A;

Figure 4L is an end view in cross-section of the layer shown in Figure 4K;

Figure 5A is a top view of a screen in accordance with the present invention, the screen comprising a top layer, a middle layer and a bottom layer;

Figure 5B is an enlarged top view of part of the screen shown in Figure 5A;

Figure 5C is an enlarged top view of the centre of the screen shown in Figure 5A;

Figure 5D is a view in cross-section taken along line 5D-5D of Figure 5A; Figure 5E is a view in cross-section taken along line 5E-5E of Figure 5A;

Figure 5F is a top view of the top layer of the screen shown in Figure 5A;

Figure 5G is an end view in cross-section of the layer shown in Figure 5F;

Figure 5H is a top view of the middle layer of the screen shown in Figure 5A;

Figure 51 is an end view in cross-section of the layer shown in Figure 5H; Figure 5J is a side view in cross-section of the layer shown in Figure 5H;

Figure 5K is a top view of the bottom layer of the screen shown in Figure 5A;

Figure 5 L is an end view in cross-section of the layer shown in Figure 5K;

Figure 6A is a top view of a screen in accordance with the present invention, the screen comprising a top layer, a middle layer and a bottom layer;

Figure 6B is an enlarged top view of part of the screen shown in Figure 6A;

Figure 6C is an enlarged top view of the centre of the screen shown in Figure 6A; Figure 6D is a view in cross-section taken along line 6D-6D of Figure 6A;

Figure 6E is a view in cross-section taken along line 6E-6E of Figure 6A;

Figure 6F is a top view of the top layer of the screen shown in Figure 6A;

Figure 6G is an end view in cross-section of the layer shown in Figure 6F ;

Figure 6H is a top view of the middle layer of the screen shown in Figure 6A; Figure 61 is an end view in cross-section of the layer shown in Figure 6H ;

Figure 6J is a side view in cross-section of the layer shown in Figure 6H ;

Figure 6K is a top view of the bottom layer of the screen shown in Figure 6A;

Figure 6L is an end view in cross-section of the layer shown in Figure 6K;

Figure 7A is an exploded perspective view of three layers of a screen in accordance with the present invention;

Figure 7B is a top view of a screen in accordance with the present invention made with the layers of the screen shown in Figure 7A;

Figure 7C is a top view of a screen in accordance with the present invention;

Figure 8 shows a table for use in a method in accordance with the present invention; Figure 8A is a chart for use in a method in accordance with the present invention; and

Figure 8B is a chart for use in a method in accordance with the present invention.

Figure 9A is a perspective view of a screen assembly in accordance with the present invention;

Figure 9B is an exploded perspective schematic view of the screen assembly shown in Figure 9A;

Figure 9C is a top view of the screen assembly shown in Figure 9A; Figure 9D is a top view of the frame of the screen assembly shown in Figure 9A;

Figure 1OA is a top view of a frame for use with screens in accordance with the present invention;

Figure 1OB is an end view of the frame shown in Figure 1OA;

Figure 1OC is an end view of the frame shown in Figure 1OA opposite the end shown in Figure 1OB;

Figure 1OD is a side view of the frame shown in Figure 1OA; Figure 1OE is a cross-section view of a feed end of the frame shown in Figure 1OA;

Figure 1OF is a cross-section view of a side of the frame shown in Figure 1OA; and

Figure 1OG is a cross-section view of a discharge end of the frame shown in Figure 1OA.

Figures IA to 2D illustrate a screen having aligned wires. As shown in Figures IA and IB, wires 1, 2, 3, each in a screen layer a, b, c, respectively are aligned

with each other vertically. As viewed from above (Figure IB) the wires 1, 2, 3 are in line vertically (at a ninety degree angle to the planes of the screen layers) and, as shown in Figure IB, parallel to each other. It is within the scope of the present invention to provide a screen assembly with a layer or layers of screen cloth in which wires have a non-round cross- section (whether such a layer is used in a screen or screen assembly without wires aligned or with wires aligned in accordance with the present invention) . Figure 1C shows part of a screen assembly in accordance with the present invention with screen cloth layers d, e. f with aligned wires 4, 5, 6, respectively. Wires 5 and 6 have non-circular, oval cross-sections. Figure ID shows a portion of a screen in accordance with the present invention with screen cloth layers g, h, i with aligned wires 7, 8, 9, respectively. Wires 7 is substantially oval and 8 rectangular with rounded corners and are thus both non-circular in cross-section. As shown in Figures 2A and 2B wires 10, 11, 12 of screening material layers d, e, f, respectively are aligned with each other on a line that is at an angle to the plane of the screen layers (the plane of a screen assembly with such layers; e.g. as shown at an angle at about 45 degrees to the screen assembly plane) . As viewed along this line the three wires 10, 11, 12 would appear as in the view of the wires 1 , 2 , 3 in Figure IB . It is desirable that the wires (e.g., 1, 2, 3 or 10, 11, 12) are parallel to each other along their entire lengths .

Figure 2C shows a screen with layers m, n, o with aligned wires 13 (oval) , 14 (oval) , and 15 (rectangle with rounded corners) , respectively, with non-circular

cross-sections .

Figure 2D shows a screen with layers p, q, r with aligned wires 16 (square) , 17 (rectangular) and 18 (rectangle with rounded corners) , respectively with non- round cross-sections.

Figures IA to 2D are illustrative and are meant to show how wires in a particular screen or screen assembly are in alignment, or substantially all the wires are aligned, or the majority of wires in the entire screen layers depicted are aligned.

Figures IE and IF illustrate two layers of screening material of a screen SC in accordance with the present invention with aligned wires . In Figure IE the shute wires of both layers extend left-to-right and the warp wires , shown as circles , go into/out of the page . In Figure IF, the warp wires are shown as extending left-to- right and the shute wires , shown as circles , go into/out of the page. A weaving angle for the top layer is 16.3 degrees ; a weaving angle for the bottom layer is 9.7 degrees. Angle N in Figure IF illustrates a weaving angle .

For the specific layers shown in Figure IE and IF, the numerical measurements are in microns, e.g. "113" indicates 113 microns. As shown in Figure IE wires a and b of the top layer are perfectly aligned with wires x and y of the lower layer. Also, wire c of the top layer can move toward the lower layer into a space s adjacent a wire z of the lower layer and a wire d can nest in a space r. In effect, wires x "masks" wire a and wire y "masks" wire b so that the screen SC has relatively more open areas than if the wires a and b were offset from the wires x, y, (respectively) .

A ratio of wires spanning 339 microns of the screen SC as viewed in Figure IE (ratio of top warp wires to lower warp wires) is 3:2 (one half wire a plus wire e plus wire c plus one half wire b - or three wires - above two wires, one half wire x, plus wire y, plus one half wire z - or two wires) . As shown in Figure IE, which has a wire count ratio of 3:2 for the top and middle warp wires, then, perfect alignment occurs if every third warp wire on the top layer aligns with every second warp wire of the layer below (as is shown in Figure IE) - i.e., two out of five wires are aligned or 40% alignment is achieved in one direction. In certain aspects of embodiments of the present invention, wires in one layer are aligned with wires in another layer according to the chosen wire count ratio (chosen in accordance with the present invention) . Thus with a top to middle wire count ratio of 5:2 in one direction, e.g., for the top and middle warp wires , every fifth warp wire of the top layer aligns with every second warp wire of the layer below - i.e., two out of seven wires are aligned or alignment of 28.5% is achieved in one direction. Thus, in accordance with the present invention, wires are "aligned" when wire count ratios are as selected in accordance with the present invention . A ratio of wires spanning 565 microns of the screen SC as viewed in Figure IF (ratio of top shute wires to lower shute wires) is 5:2. (The top layer has square openings ; the lower layer has rectangular openings . )

As shown in Figure IF wires f and k of the top layer are perfectly aligned with wires t and v of the lower layer .

Figures 3A to 3L show a screen 300 in accordance with the present invention and parts of it. The screen

300 has multiple mesh layers: a top layer 301; a middle layer 302 ; and a bottom layer 303. As shown in Figures 3B and 3C, the wires of each layer are aligned with the wires of the other two layers .

In one particular embodiment of a screen 300, the layer 301 has warp wires 301a and shute wires 301b; the layer 302 has warp wires 302a and shute wires 302b; and the layer 303 has warp wires 303a and shute wires 303b. The number of each of these types of wires per inch, wire diameters, and spacings AA, BB, CC, DD, as viewed from above , are as follows :

No. /inch Diameter Spacing

(inches) (inches)

301a 111 0.00250 0.0090

301b 111 0.00250 0.0090

302a 74 0.00360 0.0135

302b 44 0.00360 0.0227

303a 30 0.00750 0.0333

303b 30 0.00750 0.0333

No. /mm Diameter Spacing

(mm) (mm)

301a 4.4 0.06 0.23

301b 4.4 0.06 0.23

302a 2.9 0.09 0.34

302b 1.7 0.09 0.57

303a 1.2 0.19 0.85

303b 1.2 0.19 0.85

Figures 4A to 4L show a screen 400 in accordance with the present invention and parts of it. The screen

400 has multiple mesh layers 401 (top) , 402 (middle) and 403 (bottom) . As shown in Figures 4 B and 4C, the wires of each layer are aligned with the wires of the other two layers . In one particular embodiment of a screen 400, the layer 401 has warp wires 401a and shute wires 401b; the layer 402 has warp wires 402a and shute wires 402b; and the layer 403 has warp wires 403a and shute wires 403b

(warp wires across from left/right or right/left, Figure 4B; shute wires intersect warp wires - as is also true for Figures 3B, 5B, and 6B) . The number of each of these wires per inch, wire diameters, and the wire spacings EE,

FF, GG, HH (as viewed from above) are as follows:

No. /inch Diameter Spacing ( (iinncchheess)) (inches)

401a 225 0.00130 0.0044

401b 225 0.00130 0.0044

402a 150 0.00190 0.0067

402b 90 0.00190 0.0011 440033aa 3300 00..0000775500 0.0333

403b 30 0.00750 0.0333

No. /mm Diameter Spacing

(mm) (mm) 440011aa 88..99 00..0033 0.11

401b 8.9 0.03 0.11

402a 5.9 0.05 0.17

402b 3.5 0.05 0.03

403a 1.2 0.19 0.84 440033bb 11..22 00..1199 0.84

Figures 5 A to 5L show a screen 500 in accordance with the present invention and parts of it. The screen

500 has multiple mesh layers : top layer 501 : a middle layer 502 ; and a bottom layer 503. As shown in Figures 5B and 5C, the wires of each layer are aligned with the wires of the other two layers .

In one particular embodiment of a screen 500, the layer 501 has warp wires 501a and shute wires 501b; the layer 502 has warp wires 502a and shute wires 502b; and the layer 503 has warp wires 503a and shute wires 503b. The number of each of these wires per inch, wire diameters, and the wire spacings II, JJ, KK, LL (as viewed from above) are as follows:

No. /inch Diameter Spacing

(inches) (inches)

501a 90 0.00300 0.0044

501b 90 0.00300 0.0044

502a 60 0.00370 0.0067

502b 45 0.00370 0.0011

503a 30 0.00750 0.0333

503b 30 0.00750 0.0333

No. /mm Diameter Spacing

(mm) (mm)

501a 3.5 0.076 0.11

501b 3.5 0.076 0.11

502a 2.4 0.09 0.17

502b 1.8 0.09 0.03

503a 1.2 0.19 0.84

503b 1.2 019 0.84

Figures 6A to 6L show a screen 600 in accordance with the present invention and parts of it. The screen

600 has multiple mesh layers: top layer 601; middle layer 602 ; and bottom layer 603. As shown in Figures 6B and 6C, the wires of each layer are aligned with the wires of the other two layers .

In one particular embodiment of a screen 600, the layer 601 has warp wires 601a and shute wires 601b; the layer 602 has warp wires 602a and shute wires 602b; and the layer 603 has warp wires 603a and shute wires 603b. The number of each of these wires per inch, wire diameters, and the wire spacings MM, NN, 00, PP (as viewed from above) are as follows:

No. /inch Diameter Spacing

(inches) (inches)

601a 105 0.00250 0.0095

601b 105 0.00250 0.0095

602a 70 0.00350 0.0191

602b 52.5 0.00350 0.0143

603a 35 0.00700 0.0286

603b 35 0.00700 0.0286

No. /mm Diameter Spacing (mm) (mm)

601a 4.1 0.064 0.24

601b 4.1 0.064 0.24

602a 2.8 0.089 0.48

602b 2.1 0.089 0.36

603a 1.4 0.18 0.73

603b 1.4 0.18 0.73

In certain aspects a screen in accordance with the present invention (e.g., but not limited to, the screens

of Figures 3A to 7A ) are made with multiple layers of screen cloth that are stacked one on top of the other. Ideally each piece of screen cloth as received from the manufacturer has well-defined openings between wires across its entire surface. In accordance with the present invention, to insure that initially the wires of one layer line up with the wires of another layer and remain in this position during the making of a screen or screen assembly, two, three or more layers (however many are to be in the final screen or screen assembly) , are carefully positioned one with respect to the other with wires aligned and then they are connected or secured together to hold them in position for further processing. In one aspect, the multiple layers are glued together with one or more amounts of hot melt glue or a line of hot melt glue is applied along one edge of the layers and allowed to set. Alternatively any suitable known glue, epoxy, adhesive or connector (s) (e.g. but not limited to staples, rivets, clips, etc.) may be used. Figure 7A shows a step in a method in accordance with the present invention in which multiple layers of screen cloth 801, 802, 803 (three shown) are stacked together for a multi-layer screen 800. The layers are positioned so that wires in each layer align with wires in the other layers. As shown for a screen 800a with layers 801 - 803 in Figure 7B, two amounts of adhesive 804 adhere the three layers together to maintain their relative position and the alignment of the wires. One, two, three, four or more amounts of adhesive (e.g. glue, hot melt glue, epoxy, adhesive, cement, plastic, thermoplastic) may be used.

Optionally, or in addition to the amounts of adhesive 803, a staple or staples 805 may be used (or a

rivet or rivets 807, as in Figure 7C). Any suitable connector may be used (staple, rivet, clip, screw.

As show in Figure 7C in a screen 800b with layers 801 - 803, a line of adhesive (e.g., but not limited to, a line 806 of hot melt glue) is applied to the layers 801 - 803 to connect them together. In any embodiment of the present invention an adhesive and/or a connector can be applied manually or by a machine .

In any embodiment of a multi-layer screen in accordance with the present invention, the layers may be unconnected to each other or any two adjacent or all layers may be connected together.

In any screen in accordance with the present invention with multiple layers , all layers can have wires of the same diameter or wires in each layer can be of different diameters .

In certain aspects placing one layer selected in accordance with the present invention on top of another layer selected in accordance with the present invention in combination results in desired alignment (e.g. before the combination of a panel having multiple openings with mesh layers) and/or the force of fluid and/or vibratory force contributes to this alignment. It is within the scope of the present invention by selecting wire screen layers as described above (any embodiment) with wire count ratios in accordance with the present invention to achieve a substantial amount of wire alignment between wires of layers of screening material; e.g., in certain aspects, in a multi-layer screen in accordance with the present invention, to achieve such alignment of at least 30%; of at least 50%; or, in some cases, at least 70%. The percentage of aligned wires in one direction achieved in accordance with the present invention is based on the

wire count ratio for that direction.

Figure 8 illustrates one method in accordance with the present invention for selecting layers of wire screening material for a screen in accordance with the present invention having aligned wires in accordance with the present invention. The method includes steps 1 to 9.

In step 1 a basis point is selected for the top layer of the screen - which determines whether it will be fine or coarse. In one aspect, a screen mesh can be selected with a top warp opening in microns between 25 to

500 microns.

Once the top warp opening size of the top layer is selected, a wire diameter for wires in the top layer is determined by multiplying the selected top warp opening size by a multiplier, e.g. between 0.1 to 1.1 (based on experience and desirable resulting wire diameters) . In one particular aspect, no result finer than 0.0010 inches (0.025 mm) is used (step 2a).

In step 3 an aspect ratio is selected (in one aspect, in step 3a, between 0.25 to 4.00) with 1.0 being the aspect ratio for a square opening. Alternatively, in step 3b, a top layer warp weaving angle is selected, e.g. between 5 and 45 degrees.

At the end of step 3, the top layer's warp opening, wire diameter, and aspect ratio are determined.

Steps 4 - 6 deal with the middle layer of a three layer screen. In step 4 a count ratio is selected, the count ratio between the top warp wires (per unit length) and the middle warp wires (per unit length) , with the numerator and denominator in each ratio being an integer or nearly an integer (e.g. within ± 0.1 of an integer); in one aspect, with the integers between 1 and 10 and with the resulting count ratio being 0.1 to 10. Step 4,

therefore, yields the warp count for the middle layer.

In step 5, the shute count for the middle layer is determined in a manner similar to that of step 4 for warp count . In step 6, the diameter of the wires of the middle layer is determined by using step 6a or step 6b. In step 6a a constant ratio is chosen (based on experience) of top layer wire diameter to middle layer wire diameter, e.g. in a range between 0.2 to 5; or, in step 6b, a wire diameter is calculated based on results from step 1 (e.g. using a simple formula function based on the numerical result of step 1) .

Steps 7 to 9 deal with the lowermost bottom layer of a three layer screen. In step 7 the lowermost layers warp count is determined (e.g. as in step 4, above for the middle layer) , in one aspect, with integers ranging between 1 and 10. In step 8, the lowermost layer's shut count ratio is determined (e.g. as in step 5, above, for the middle layer) . In step 9, the diameter of the wires of the lowermost layer is determined (e.g. as in step 6, above, for the middle layer) .

Figure 8A and 8B show values , measurements , and ratios for screens 1 - 6 in accordance with the present invention determined with the method of Figure 8. "TMDR Value" is top-to-middle diameter ratio. "MBDR Value" is middle-to-bottom diameter ratio.

Figures 9A and 9B show a screen assembly 900 in accordance with the present invention which has ends 90Og, 90Oh and a frame 910 on which are secured a plurality of screening layers 901, 902, 903 with a panel 904 applied to the screening layers. In certain aspects the frame 910 is made of sheet metal, e.g. aluminium, stainless steel, or composite material, or fiberglass.

The screening layers 901-903 are any suitable known screening material, e.g., but not limited to, screen cloth of multiple spaced-apart wires of stainless steel; and the panel 904 is any suitable material, e.g. mild steel or mild steel coated with cured epoxy. In Figure 9B the layers 901-903, the panel 904, and the frame 910 are shown somewhat schematically without all the detail of other figures. Any one or two of the layers 901-903 may be deleted. Peripheral edges of the panel 904 and/or of the screening layers 901-903 are connected, secured, and/or adhered to the sides 910a, 910b and the ends 91Og, 91Oh of the frame 910. In one aspect, the panel edges and the screening layer edges are epoxied to the frame. Optionally, the frame 910 has a plurality of holes or recesses 912 (and the panel 904 has holes 912p) which receive an amount of epoxy that secures the screening layers. The holes 912, in one aspect, are not aligned with the holes 912p. In another aspect, the holes 912 and the holes 912p are aligned. The holes 912 go all the way through the frame but it is within the scope of the present invention for the holes 912 to project into the frame without penetrating all the way through.

Optionally, the panel 904 has the majority of its area formed with hexagonal openings 904a. Optionally, several of these openings, openings 904b, have a crossbar 904c, for added strength and wear resistance. The openings 904c extend along two sides of the screen assembly at locations of expected relatively high solids impact and/or locations of high accumulation of separated solids. Optionally, the panel 904 has elongated hexagon openings 904d (one or, as shown, two rows, or more rows) each with a crossbar 904e for added strength and wear

resistance. Optionally the panel 904 has areas 904f at the end 904g adjacent the openings 904d. Relatively more panel material defines the openings 904f, hence, they present a stronger area to material flowing thereon. Also, a corresponding shape of the frame 910, edge 91Of, underlies the areas 904f and there is no flow through the areas 904f. For example, in certain aspects, a screen assembly 900 is positioned on a vibratory separator or shale shaker so that material is fed to the screen assembly to initially fall on the end 90Og at which the panel 904 has the openings 904d and/or areas 904f and/or openings 904b since the impact of the material and its effects can be greater at a feed end of the screen. An exit end 90Oh of the screen assembly may also have some or all of these areas and openings; as shown, the panel 904 at the exit end 90Oh has areas 904k (like the areas 904f) . Optionally, the frame 910 includes then edge 91Of which corresponds in shape to the areas 904f. Optionally, the frame 910 has a plurality of crossbars 910s (or crossmembers or cross strips) .

As shown in Figures 9A and 9C, in one particular aspect a screen in accordance with the present invention has , as seen from above , a generally "W" shaped area that includes the areas 904f, the openings 904c, the openings 904d, and a plurality of central openings 904K (three shown) which cover a portion of the screen area which, in certain uses, is subjected to relatively increased impact, and/or relatively increased solids accumulation and/or wear, and/or relatively larger forces. The openings 904c, 904d and 904k each has a crossbar.

The openings of the panel 904 may be any desired shape as viewed from above and crossbars may be used with any shape. Any shape may be used for the majority of the

panel ' s area with elongated shapes used at certain areas , e.g. at one or both ends. In one particular aspects, the openings 904a are regular hexagons with a side-to-side length L of 46πun (1.83 inches) which is about 8% larger than the side-to-side length of some commonly-used hexagonal panel openings .

In certain aspects , the elongated hexagonal openings 904d have a side-to-side length that is at least 15% greater than a comparable non-elongated hexagon. In one particular aspect, with a side-to-side length between elongated sides which are 46mm (1.83 inches) apart, the side-to-side length M is 56mm (2.198 inches).

In certain aspects , a panel with hexagon openings with a larger side-to-side length L is used with one or more screening material layers which have wires of relatively larger diameter; e.g., see screens 1 - 6 as described in Figures 8A, 8B.

In certain aspects, in screen assemblies in accordance with the present invention in which wires with relatively larger diameters are used, the wires are spaced-apart a relatively larger distance so that screen open area is not significantly reduced because of the use of larger wires; for example, see screens 1 - 6, Figures 8A, 8B. In certain aspects, screen assemblies in accordance with the present invention have a top layer of wire screening material that has generally square openings and a lower layer beneath the top layer which has non-square rectangular openings . In certain aspects , in such a screen assembly in accordance with the present invention the ratio of wire count (number of wires per unit of length) for the top layer to wire count for the middle layer (or bottom layer if there are only two layers) is a

ratio of whole numbers , whether or not there is a whole number of wires per inch in each layer.

In one particular embodiment the wires of screens are in a 1:1.5 ratio in one direction and a 1:2.5 ratio in the other direction so that across the first direction 1 of 3 openings formed by the top mesh are unobstructed by a wire in the second mesh in that direction, while in the other direction 3 of 5 openings formed by the top mesh are unobstructed by a wire in the second mesh in that direction. In this particular embodiment, when these ratios are maintained, the middle mesh has a count ratio (warp to shute) of 1:1.7.

In one particular screen assembly in accordance with the present invention ("Embodiment A"), the screen assembly has three layers of screening material, each with wires of stainless steel, including a lowermost layer of tensile bolting cloth ("TBC") , a middle layer with generally non-square rectangular openings; and a top layer with generally square openings . The wire count for each layer and warp and shute wire diameters are as follows : Embodiment A

Mesh Type Warp Shute

Count Diameter Count Diameter

TBC layer 4.7 0.066mm 4.7 0.066mm

Middle layer 2.9 0.091mm 1.7 0.091mm

Top layer 4.4 0.064mm 4.4 0.64mm

Mesh Type Warp Shute

Count Diameter Count Diameter

TBC layer 120 0.0026" 120 0.0026 Middle layer 74 0 .0036" 44 0 .0036 Top layer 111 0 .0025" 111 0 .0025

In such a screen assembly, the mesh count of the top layer is lower than the mesh count of the TBC layer (with similar wire diameters) so the weaving angles of the top layer are generally less and, therefore, the wires of the top layer can move relatively more than the wires of the TBC layer. Comparable previous known screen assemblies ("B" and "C" below) have the following characteristics for top and middle layers (employing the same TBC lowermost layer) :

B : Square Openings : Top & Mid Layers

Mesh Type Warp Shute

Count Diameter Count Diameter

Top layer 5.1 0.043mm 5.1 0.043mm

Middle layer 3.9 0.058mm 3.9 0.064mm

Mesh Type Warp Shute

Count Diameter Count Diameter

Top layer 130 0.0017" 130 0.0017"

Middle layer 100 0.0023" 100 0.0025"

C : Rectangular Openings : Top & Mid Layers

Mesh Type Warp Shute

Count Diameter Count Diameter

Top layer 6.7 0.043mm 4.1 0.043mm

Middle layer 4.1 0.064mm 2.5 0.064mm

Mesh Type Warp Shute

Count Diameter Count Diameter

Top layer 170 0.0017" 105 0.0017"

Middle layer 105 0.0025" 64 0.0025"

The screen assembly of Embodiment A in accordance with the present invention has a top square opening mesh layer which is more stable than the rectangular openings of the C screen assembly since less relative movement of wires occurs with square openings . By using a wire diameter (e.g. 0.064mm (0.0025")) for the top layer that is relatively larger than the wire diameters of the top layers of screen assemblies B and C (0.043mm (0.0017")), the strength of the top layer of the screen assembly in accordance with the present invention is increased. A layer in a screen in accordance with the present invention with "square" openings has openings that are square within manufacturing tolerances; i.e., the square openings may not be exact perfect squares .

In any of these screen assemblies in accordance with the present invention the top, middle, and/or lowermost support layers can be calendared. Calendaring can enhance wire alignment.

In certain screen assemblies in accordance with the present invention (one example being Embodiment A above) , the top layer has a mesh wire count ratio of 1:1 (i.e., for a 1:1 ratio , the ratio of the number of wires in one direction is the same as the number of wires in the other direction) or nearly 1:1 (ratio X), e.g. 1:0.9; the wire count ratio (ratio Y) in a first direction of two directions (warp or shute) between the top layer and the

layer below the top layer (e.g. a middle layer), is between 1:1.25 and 1:1.75; and the count ratio (ratio Z) between the top layer and layer below the top layer in the second of the two directions is between 2.25 and 2.75. In such screen assemblies the wire diameters of wires in the top layer and the layer below the top layer can be different or the same. In one particular embodiment, specific ratios are as follows:

Ratio X - 1:1 Ratio Y - 1:1.5

Ratio Z - 2.5

In certain aspects , wire diameter for wires in a top layer range between 0.028mm and 0.14mm (0.0011 to 0.0055 inches) and wire diameter for wires in a middle layer range between 0.028mm and 0.14mm (0.0011 to 0.0055 inches); and wire diameter ratios, top wire diameter to middle wire diameter, range between 0.72 and 0.68. In certain aspects the wire diameter of wires in a top layer are not smaller than 0.0010". Figures 1OA to 1OG show a frame 1000 which can be used with the screen of Figure 8A (or any screen in accordance with the present invention) . The frame 1000 has sides 1000a, 1000b and ends 100Od, 100Oe. In one aspect the end lOOOd is a feed end for the screen 1000 and end lOOOe is a discharge end. The frame 1000 has cross supports 1002 and scalloped edges 1004. Optionally, a lower series of cross-supports 1006 are also used which extend across the frame 1000 as do the cross supports 1002. The present invention, therefore, provides in at least certain embodiments, a screen for a vibratory separator, the screen having at least two layers of screening material, the at least two layers of screening

material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires , the second layer made of a plurality of intersecting second wires, the first layer above the second layer, each of a plurality of the first wires aligned with a corresponding second wire according to a preselected wire count ratio, a panel combined with the at least two layers of screening material, the panel having multiple spaced-apart openings , a plurality of the multiple spaced-apart openings having a central crossmember extending from a first side of an opening to a second side thereof, said plurality of openings in a pattern on the panel as viewed from above, and a support for the panel and the at least two layers of screening material. Such a screen may have one or some, in any possible combination, of the following: wherein the vibratory separator is a shale shaker for use on a drilling rig; wherein the at least two layers of screening material includes a third layer, the third layer below the second layer and made of a plurality of intersecting third wires , each of a plurality of the first wires aligned with a corresponding third wire, each of a plurality of the second wires aligned with a corresponding third wire; wherein the multiple spaced- apart openings include a plurality of openings with a regular hexagonal shape; wherein a side -to-side length across one of the regular hexagonal openings is 1.83 inches ; wherein the plurality of the multiple spaced- apart openings includes a plurality of openings with an elongated hexagonal shape; wherein a side-to-side length across one of the elongated hexagonal openings is 2.19 inches ; wherein the pattern includes high impact areas of the screen; wherein the high impact areas include a feed

end of the screen, a central area of the screen adjacent the feed end, and two side areas of the screen each adjacent the feed end; wherein the support is a frame; wherein the support has two spaced-apart ends, each of the two spaced-apart ends having a shaped edge, the shaped edge having a shape corresponding to a shape of a portion of the multiple spaced-apart openings ; and/or wherein the shaped edges block flow through the at least two layers of screening material . The present invention, therefore, provides in at least certain embodiments, a screen for a vibratory separator, the screen having at least two layers of screening material, the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires , the second layer made of a plurality of intersecting second wires, the first layer above the second layer, each of a plurality of the first wires aligned with a corresponding second wire according to a preselected wire count ratio, a panel combined with the at least two layers of screening material, the panel having multiple spaced-apart openings, a plurality of the multiple spaced-apart openings having a central crossmember extending from a first side of an opening to a second side thereof, said plurality of openings in a pattern on the panel as viewed from above, a support for the panel and the at least two layers of screening material, wherein the at least two layers of screening material includes a third layer, the third layer below the second layer and made of a plurality of intersecting third wires, each of a plurality of the first wires aligned with a corresponding third wire, each of a plurality of the second wires aligned with a

corresponding third wire, and wherein the pattern includes high impact areas of the screen.

The present invention, therefore, provides in at least certain embodiments, a screen for a vibratory separator, the screen having at least two layers of screening material, the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires , the second layer made of a plurality of intersecting second wires, the first layer above the second layer, the first layer having a warp-to-shute wire count ratio A between 0.9 and 1.1, a wire count ratio B in a first direction between the first layer and the second layer is between 1 to 1.25 and 1 to 1.75, and a wire count ratio C in a second direction different than the first direction between the top layer and the second layer is between 2.25 and 2.75. Such a screen may have one or some, in any possible combination, of the following: wherein the ratio A is 1:1, the ratio B is 1:1.5, and the ratio C is 2.5; wherein wires in the first layer range in diameter in inches between .0011 and .0055, wires in the second layer range in diameter in inches between .0011 and .0055, and a ratio of diameters of wires of the first layer to diameters of wires in the second layer ranges between 0.72 and 0.68; wherein the first layer and the second layer are calendared together; wherein the vibratory separator is a shale shaker for use on a drilling rig; and/or wherein the at least two layers of screening material includes a third layer of screening material .