Page 244 - Shale Shakers Drilling Fluid Systems
P. 244
APPENDI X B
Equipment Guidelines
When the American Petroleum Industry work- drilled solids from the system, new fluid must
group met to edit and approve the API 13C equip- be built quickly. The volume of new fluid is the
ment guidelines, "Practical Operational Guide- sum of the solids removed and the drilling fluid
lines," each item was discussed in depth. Some of clinging to them. Mixing equipment on rigs is
those considerations are included here along with not usually geared to rapid additions of drill-
some additional thoughts concerning solids re- ing fluid products. Drilling operations experi-
moval equipment. The equipment discussed in this ence fewer problems if the drilling fluid prop-
appendix is all-inclusive and may not apply to all erties are controlled, which is difficult with
drilling applications. large, rapid additions of drilling fluid products.
3. All removal compartments, except the sand trap,
SURFACE SYSTEMS should be well stirred or agitated to ensure even
loading of solids removal equipment.
1. The surface system should be divided into three Solids control equipment works best when the
sections each having a distinct function: Removal solids loading remains constant. Slugs of a
Section, Addition Section, and Check/Suction large quantity of solids tend to plug the lower
Section. Undesirable drilled solids should be re- discharge opening in desilters. When this oc-
moved in the Removal Section. All mud material curs, drilled solids will not be removed until
and liquid additions should be made in the Ad- the plugged cones are cleaned. On a rig, even
dition Section. The Check/Suction Section pro- with diligent crews, some cones will usually
vides volume for blending of new mud materi- remain plugged, which leads to increased drilled
als and verification of desired mud properties. solids in the drilling fluid.
This is a simple concept that requires each
surface system to have three easily identifiable 4. The ideal tank depth would be approximately
sections. If not, changes will quickly pay for equal to the width, or the diameter, of the tanks.
themselves. If deeper, special considerations may be neces-
sary for stirring; if shallower, adequate stirring
2. Minimum recommended "usable" surface mud without vortexing will be difficult or impossible.
volume is 100 barrels (less for slim holes) plus Baffles will help prevent vortexing. When us-
enough to fill the hole when the largest drill ing vertical blade stirrers in circular tanks,
string the rig can handle is pulled wet and all baffles are a necessity.
the mud inside the string is lost. In order to
maintain fluid properties in large diameter, soft, 5. Use top equalization for the sand trap.
fast-drilling holes, the minimum surface volume To take advantage of the maximum settling
should be at least five or six times the volume
of the hole drilled per day. time, fluid should enter the upstream end of
the sand trap. After the fluid moves through
For safety reasons a rig must have enough the compartment, it exits through an overflow
drilling fluid to fill the hole at all times. This weir into the next compartment. An underflow
is the situation described above. A second arrangement would carry settled solids into
consideration is not a safety feature but a the next compartment.
recognition of practicality. When rapidly drill- The ability to use 200-mesh screens on
ing a large diameter hole and removing the shale shakers means most of the "sand-sized"
226
