Page 148 - Shale Shakers Drilling Fluid Systems

SHALE SHAKER SCREENS 131

TABLE 6-8. Typical Market Grade and Tensile Bolting Cloth Shaker Screen Characteristics

Separation Potential
Screen Designation in Microns Conductance
Mesh Kd/mm
d, 6 d 50 d 84
Market Grade 10x10 1727 1777 1678 49.68
20x20 864 889 839 15.93
30x30 516 531 501 8.32
40x40 381 392 370 4.80
50x50 279 287 271 2.88
60x60 234 241 227 2.40
80x80 177 182 172 1.91
100x100 140 144 136 1.44
120x120 117 120 114 1.24
150x150 105 108 102 1.39
200x200 74 76 72 0.68
250x250 62 63 59 0.58
325x325 44 45 43 0.44
Tensile Bolting Cloth 20x20 1041 1071 1011 40.93
30x30 681 700 662 24.33
40x40 470 483 457 11.63
50x50 368 379 357 7.94
60x60 310 319 301 5.60
70x70 269 277 261 5.25
80x80 224 230 218 3.88
94x94 180 185 175 2.84
105x105 165 170 160 2.77
120x120 147 151 143 2.51
145x145 119 122 116 2.03
165x165 107 110 104 1.86
200x200 86 88 84 1.49
230x230 74 76 72 1.30

Screen panels are popular because screen tears and shape of the screen openings will influ-
are minimized and limited to only one small area ence how fine a separation is made. This is
of the screening surface. The screen panels, how- reflected in the percent separated curve. If all
ever, reduces the amount of available screening drilled solids are spherical, then the distribu-
area that, in comparison, is totally available with tion of the narrowest dimension of the screen
continuous cloth screens. The non-blanked area openings will establish the percent separated
allows an evaluation of the surface area available curve. Conversely, if the particles being sepa-
for liquid transmission through the screen. rated are shaped like the screen openings,
then the separation curve will be closer to an
Factors Affecting Percent ellipsoid, which will barely pass through the
Separated Curves screen openings. If a range of solids, from
blocky to slivers, is drilled, then the separation
curve, again, will be closer to an ellipsoid that
Some of the factors that affect the actual separa- will barely pass through the screen openings.
tion made by a screening operation are as follows:
Solids have mobility in a pool of fluid to
• The relationship between the size and shape seek a screen opening large enough to pass
of the particles being separated and the size through. As a result, the conveyance velocity,