Page 133 - Shale Shakers Drilling Fluid Systems
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116 SHALE SHAKERS AND DRILLING FLUID SYSTEMS
11. Provide the proper electrical voltage and 4. Do not bypass the shale shaker screens or
frequency. Low line voltages reduces the operate with torn screens; these are the main
life of the electrical system. Low frequency causes of plugged hydrocyclones. This results
reduces the motion and lowers the capac- in an accumulation of drilled solids in the
ity of the shale shaker. drilling fluid. Also, do not empty the back
12. Check for proper motor rotation. tank into the pits (for cleaning purposes,
13. Check for proper motion of the shale shaker etc.) since this is considered a form of by-
deck. passing the shale shaker.
14. Check drive belts for proper tension accord- 5. All drilling fluids that are not processed by
ing to manufacturer's instructions. solids removal equipment and are intended
15. Screens should be installed according to to be added to the active system, should be
manufacturer's instructions. screened by the shale shakers to remove un-
16. Provide a wash-down system for cleaning. desirable solids. Specifically, this includes
17. Water-spray bars, if installed, should provide drilling fluid delivered to a location from re-
only a mist of water—not a stream of water. mote sources.
OPERATION
MAINTENANCE
1. For double-deck shale shakers, run a coarser
mesh screen on the top deck and a finer 1. For improved screen life with nontensioned
mesh screen on the bottom The coarser screen screens, ensure the components of the screen
should be at least two standard mesh sizes tensioning system, including any rubber
coarser. Watch for a torn bottom screen and supports, nuts, bolts, springs, and so forth,
replace or patch torn screens at once. Dur- are installed and properly operating. Install
ing normal drilling operations, cover at least screens according to the manufacturer's
75% to 80% of the bottom screen with drill- recommended installation procedure.
ing fluid to maximize utilization of available 2. Lubricate and maintain the unit according
screen area. Properly designed flow-back pans to the manufacturer's instructions. Some
may improve shaker performance. (Gumbo units are self-lubricating and, therefore,
shakers mounted above as an integral part this step should be skipped.
of linear shale shakers are not called double- 3. Check the screen tension one, three, and
deck shale shakers—although the operation eight hours after installation and hourly
guidelines above still apply.) thereafter.
2. For single-deck shale shakers with multiple 4. Check the tension of drive belts and make
screens on the deck, run the same mesh any adjustments according to the manu-
screens throughout. If coarser screens are facturer's instructions.
necessary to prevent drilling fluid loss, run 5. If only one deck of a multiple-deck shaker
the finer mesh screens closest to the back is used, make sure other tension rails are
tank. All screens should have approximately secured.
the same size openings. For example, use a 6. Wash screen (s) at the beginning of a trip so
combination of market grade (MG) 100 mesh as not to allow fluid to dry on the screen (s).
(140 microns) and MG 80 mesh (177 mi- Do not empty the back tank into the active
crons), instead of MG 100 mesh (140 mi- system or the sand trap below the shaker.
crons) and MG 50 mesh (279 microns). Under This results in plugged hydrocyclones down-
normal drilling conditions, cover at least 75% stream and/or an increase in drilled solids
to 80% of the screen area with drilling fluid concentration in the drilling fluid.
to properly utilize the screen surface area. 7. Inspect screens frequently for holes and re-
3. Spray bars (mist only) may be used for sticky pair or replace any that are torn.
clay to aid conveyance, which reduces whole 8. Check the condition of vibration isolators
drilling fluid loss. High-pressure washers and screen support rubbers and replace
should not be used on the screen(s) while if they show signs of deterioration or wear.
circulating because they disperse and force 9. Check the fluid bypass valve and the area
solids through the screen openings. Spray around the shaker screens for leaks.
bars are not recommended for weighted or 10. Remove drilling fluid accumlation from vi-
oil-based drilling fluids. brating bed, vibrators, and motors. Caution:
