Note: Descriptions are shown in the official language in which they were submitted.
: 1134783
This invention relate~ to a proce~ and
~ystem for the recovery of relatively low gravity
particulate material, ~uch a~ copolymer beads, from
a drilling fluid ~o that ~uch materisl can be re-
S circulated through the well with the drilling fluid
During the drillin~ of a well, it i~ com~on
practice to pa~ the drilling aud return~ containing
drill-d solid~ through a shale ~haker or the like to
remov- a~ many of the solids from the mud ~8 i8 pO~-
~lSlo. ~hiJ i~ de~lr~ble bacaus~ reclrculated drilled
Jolid~ tend to be ground lnto finer and finer ~i~e~,
thereby building up the solids content o~ the mud
As the ~olid~ content increa~es, the mud must be
thinned by adding ~ddltional water, which nece~itates
lS the addition of mor- w ighting material to maintaln
the mud at it~ d-~ired weight For the~e ~nd other
rea~ons, it i~ de~irable ln many case~ for the returned
mud to b- of a low drilled ~olids content In order
to provide such a mud, it i~ conventional to screen
the mud ln a shalo ~hak~r having screen~ ranging ln
~ize ~rom 10 to 200 me~h with the average me~h ~i~e
belng from about 20 to 80 me~h. Hereto~ore, any ~olld
additivc, uch a~ lubricating copolym~r bead~ and
lost circulation mat-rials, having a particle size
larger th~n that of the shale ~haker screan, would
be removed fro~ the ~y~tem ~ith the drilled ol~d~
A~ a result and as a practlcal ~atter, such particulate
materiRl i8 circulated once through the system and is
then discarded If it i~ de~ired to maintain the
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partieulate mater~al in the sy~te~ for several clreula-
tion~, addltional material has to be added to co~pen~ate
for that removed by the ~hale shaker. This can be
relatively expen~ive.
It i-, therefore, an object of thi~ invention
to provlde an apparatu~ and proce~s which ~ill permit
recirculation of particulate material, e~pecially co-
polymer beads, in a well, wh~le at the same t~me removing
drilled solid~, at lea~t a part of which has a partiele
0 8ize approximating that of the particulate material,
thereby permitting the maintenance of a low ~olids
~ystem.
Another ob~ect iJ to provide ~uch an apparatus
and sy~tem for th- reeovery of an added partieulate
material fro~ a drilling ~ud, even though uch mud
eontain~ drilled olid~ havlng a partlele 8iZ¢ of
the order of that of the particulate materlal.
In aeeordanee wlth this invention, the
drilling mud containing an added particulate material
having a ~pecific gravity ~ub~tantially le~ than that
of the drilled solids i~ separated into a fir~t fraetion
consisting essentially of the drilling mud and a second
fraction comprising the particulate mater$al and th~
drilled euttings. The latter fraction 1~ then passed
into a separating zone or apparatus containing a flota-
tion liqu~d having a sp~ciflc gravity le~J than that of
th~ euttlngs but greater th-n that of the particulate
~aterial. In thi~ app~atu~, the particulate material
i~ permitted to float toward the ~urface of the liquid,
1134783
while the drilled solids, being heavier than the liquid,
settle toward the bottom. The particulate material is then
skimmed from the surface of the liquid and thereafter separated
from any flotation liquid removed with the particulate mater-
ial. The thus recovered flotation liquid is then returned to
the separation apparatus for further use. Similarly, the
drilled solids can be removed from the lower portion of the
separating apparatus along with some of the liquid and then
separated from the latter so that the liquid can be returned
to the separating apparatus.
Referring now to the drawing wherein there is shown
schematically the apparatus of this invention capable of be-
ing used in performing the process, there is illustrated a
well 10 which is being drilled by a bit 11 connected to the
lower end of a drill string 12. As is conventional, drilling
mud is pumped from a mud pit 13 through a swivel 14 into the
drill string where it passes downwardly and out of the bit to
return through the annulus to return line 15.
A particularly useful application of the apparatus
and process of this invention is in connection with the use
of copolymer beads in drilling muds to reduce friction as
disclosed in my U.S. Patent No. 4,063,603, to which reference
is made. The copolymer beads can have a specific gravity
within the range of 0.5 to 2.0 and preferably from 1.1 to 1.5
~,
1134783
and are of a ~ize wlthin the range of 10 to 100 me~h
(Tyler ~tandard ~creen ~lze), preferably ~0 to 60
mesh It will be ~een that when such bead~ are used,
and when an operator i8 attemptlng to maintain a low
olld~ drilling mud by u~inq, for example, an 80 me~h
~h~kor creen, the bo-d~ ~ill be removed fro~ the
system along with the drilled ~ollds In order to
recover the~e bead~ and permit their u~e again, the
drilling mud cont~ining the drilled solids is pa~d
via lin- 16 to a conventional sh~le ~haker 17 which
c~n be equlpped with a screen having a finer me~h
slze than that of the bead~ A~ a re~ult, the
drilling mud pa~se~ through the ~creen and i~ re-
turned via line 18 to the mud pit 13
The remov~d drilled ~olids and be~ds are
pa3sed via ~ line 19 to a separating tank or ve~s~l
20 conta~ning a flotation liquid having a ~pecific
gravity les~ than that of the drilled cuttings but
greater than the bead~ A~ a result, the bead~ are
permitt~d to flo~t to the surface of tho liqu~d in
the vessel from whiGh they are removed by a ~uitable
sklmmlng apparatu~ 21, alon~ with ~ome o~ the liquid,
and paJ~ via a llno 22 to the ~eparator 23. In the
latter, the be~d~ are screened from the liquid and
can be returned via a line 2~ to the mud pit 13 for
reclrculation in th~ well The recovered liquid can
pa~ vla a ~in- 2S back ~o the ve~el 20
Similarly, the clay Jolid~ which ~ettle in
the bottom of the ve~el 20 can be removed, along with
some of ~he liquid in the ves~el, via a line 25 and
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p~ssed to another ~eparator 26~ In the latter, the
clay solid~ are separated fro~ the liquid and are dls-
charged via a line 27, while the liquid i~ returned
via llne 28 to the veJsel 20.
S The flotation liquid can be of any desired
type, provided that it ha~ the requi~itc gravity
lying between that of the partiçulate material and
the drilled ~olids. Exemplary of such liquids are
aqueou~ solution~ of ~odium carbonate, ~odium chloride,
potas~ium chloride, calcium chloride, zinc chloride
with calcium chloride, calcium bromide, 30diu~
nitrate, etc. The amount of the~e ~alts which are
dis~olved in water to form the liquid can be varied
to control the peciflc gravity of the ~olution
with~n certain rangeJ ea8ily recognizable by a
skilled chemi~t. It i~ preferred, especially when
recovering copolymer bead~, to use ~odium carbonate
because of it~ economy and inertne~s. The flotation
liquid can be prepared by addlng 110 pounds, for
exa~ple, of the 80dlu~ carbonate to 42 gallon~ of
water to yield a llquid h~ng a den~ity of a~out
1.15.
In addition to the recovery of copoly~er beads,
the apparatu~ and proce~ of thi~ invention can be
u~ed to recover other materials ~uch as conventlonal
10~Qt circulation materials. Among these are nut hull~,
c~n~ ~iber~ cotton ~eed hull~, cedar fibers, ~awdu~t
and wood chip~, rlce hull~, cellophane flakes and
~hredded leather. Alqo, lo~t circulation materials
1 1 3 ~7 ~ ~
comprising natur~l or ~ynthetic resin~ in the form of
flake~, fiber~ or particle~, can include pheno~eal,
polystyren~, polyethylene, nylon, asphalt, Gilsonite
and ground rubber.
A~ indicated, the shale shaker 17 i~ a
conventional piec- of equip~ent found on nearly every
drilling rig. Shale s~aker 26 ~nd separator 23 wlll
usually be provided a~ extra pieces of equipment and
these can be conv-ntional vibrating shaker~, hydro-
cycloneJ, centrifuge~ or other devices c-pable of
making a separation between the low density partlculate
material and the relatlvely hlgh den~ity liquid.
From the foregoing it will be seen that thi~
invention is one well adapted to attain all of the ends
and ob~ect~ hereinabove ~et forth, together with other
advantages which are obvious and which are inherent to
the method.
It will be understood ~hat certain features
and subcombination~ are of utility and may be employed
without reference to other features and subcv~blnations.
This 18 contemplatod by and i8 within the ~cope of the
cl~inl8 .
As many po~ible embodiment~ may be ~a~e of
the invention without departing fro~ the 8cope thereof,
lt is to be underQtood that all matter herein ~et forth
or ~hown in the accQmpanying drawing i8 to be interpreted
as illustrative and not ~n a limiting sen~e.
