Page 23 - Shale Shakers Drilling Fluid Systems

6 SHALE SHAKERS AND DRILLING FLUID SYSTEMS

The Second Field Model. The mud cleaner included 2 open top, single-deck Sweco
shale shakers processing underflow from sixteen, 4-inch Magcobar desilters.

Disposal, in some locations, consists of a cut- THE EVOLUTION OF SOLIDS
tings injection system that blends cuttings into a SEPARATION DEVICES
slurry inside a specially modified centrifugal pump
(shear pump). This slurry is pumped down the well As mentioned previously, during the 1920s, the
annulus between two strings of casing, or the oil well drilling industry recognized the need to
casing and wellbore. remove cuttings from the drilling fluid. The min-
An innovation recently made available on the ing industry used stationary, vibrating screens for
Gulf coast is the "gumbo chain," or gumbo screen classifying larger pieces of ore from smaller pieces.
belt. It is used to discard gumbo and large, pliable These screens were adapted to separate cuttings
cuttings typical of coastal and offshore drilling. from the drilling fluid in an evolutionary process,
The gumbo chain is a special conveyor, in a chan- which has continued through time to yield the
nel or trough, which drags gumbo and large, sophisticated solids control systems used today.
pliable cuttings out of the drilling fluid. The gumbo The early machines were called "screens" not "shak-
screen belt is an endless belt of 5-10 mesh ers," as reflected in the 1930 Oil Weekly article
synthetic cloth that moves gumbo up out of a reprinted on pages 13-14. The oilwell industry
liquid pool. This operation reduces the severe adapted mining equipment by redesigning it to
screen loading problems caused by gumbo in handle viscous liquids, reducing its weight, and
typical screening operations. The devices can be mounting it on skids to facilitate rig moves. The
mounted in the flow line or as an accessory unit history of this evolution has been documented in
in the solids control system. the World Oil's Composite Catalog.
In summary, specific requirements for a given The following is a general chronology of solids
drilling fluid system and prevailing economic fac- separation devices used in the oilwell drilling indus-
tors, will dictate the need for using specific items try. Unfortunately, some early versions are not in-
of solids removal equipment. The solids removal cluded because the scope was limited to the Com-
system may be simple using one shale shaker, or posite Catalog from the first edition (1930) through
very complex using a multiple of one or more dif- the 1978-1979 edition. The following descriptions
ferent items discussed above for complete sepa- are brief but represent the best general information
ration of solids from liquid. Factors controlling the available for each device. Additional information for
items used in a drilling fluid system include eco- each unit is presented in the following reproductions
nomics and the ever-increasing requirements of of original advertising pages taken from archival
the environmental sector. copies of the World Oil's Composite Catalog.