Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
Method and apparatus for preventing accumulations of
solids in a drilling fluid conditioning tank
FIELD OF THE INVENTION
The present invention relates to a method and an
apparatus for preventing accumulations of solids in a
drilling fluid conditioning tank, and, in particular, a floc
tank.
BACKGROIIND OF THE INVENTION
There are different types of drilling fluids that are
used when drilling an oil or gas well. One drilling fluid
that is used is floc water. Water is treated with
chemicals, typically calcium, so that solids will drop out in
the floc tanks when a polymer is added.
The floc water is pumped down the drilling string to the
drill bit. As pumping continues the drilling fluid is forced
back up an annular space referred to as the "annulus" between
the outside of the drill string and the borehole. The floc
water which passes up the annulus carries with it cuttings
from the drill bit. On surface, the floc water is passes
over a shale shaker to remove large cuttings. Polymer is
then added to the floc water, which causes the solids to join
together. As the solids join together they become heavy and
drop out of the liquid. The dirty floc water is then
directed into floc tanks.
Floc tanks have several compartments. Smaller solids
from the floc water drop out as the floc water passes from
compartment to compartment. A vacuum truck is used to suck
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up the solids that drop to the bottom of the floc tank. The
vacuum truck unavoidably draws floc water with the solids.
This adds to the cost as more water and more chemicals must
be added to replace those which have been removed. It also
causes environmental problems, as the floc water and solids
from the vacuum truck must be disposed of.
SUMMARY OF THE INVENTION
What is required is a method and an apparatus for
preventing accumulations of solids in a floc tank.
According to a first aspect of the present invention
there is provided a method for preventing accumulations of
solids in a drilling fluid conditioning tank. A first step
involves equipping the drilling fluid conditioning tank with
a high pressure water agitation gun. A second step involves
fluidizing accumulated solids by subjecting the accumulated
solids to a jet stream of high pressure drilling fluid from
the agitation gun. A third step involves circulating the
fluidized solids through a centrifuge to remove the solids
from the drilling fluid and returning the drilling fluid to
the drilling fluid conditioning tank.
According to another aspect of the present invention
there is provided an apparatus for preventing accumulations
of solids in drilling fluid conditioning tanks. This
apparatus consists of a combination of a drilling fluid
conditioning tank, a centrifuge and a high pressure water
agitation gun. The drilling fluid conditioning tank has a
bottom and a peripheral sidewall. The centrifuge is in fluid
communication with fluids in the tank. The high pressure
water agitation gun is mounted in the tank. The agitation
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gun has an outlet nozzle positioned to direct a jet stream of
high pressure drilling fluid at the bottom of the tank. This
causes solids accumulated on the bottom of the tank to be
fluidized for removal by the centrifuge.
By simply fluidizing accumulated solid for removal by
the centrifuge, as described above, the method and apparatus
addresses the problems relating to loss of chemical and
disposal of removed fluids.
Although beneficial results may be obtained through the
apparatus, as described above, it is preferred that the
agitation gun have a substantially vertical conduit and a
substantially horizontal conduit. The vertical conduit has
an axis which is positioned substantially parallel to the
peripheral sidewall of the tank. The horizontal conduit is
positioned adjacent to the bottom of the tank. The vertical
conduit is mounted within the tank for rotation about its
axis. Rotation of the vertical conduit causes the jet stream
of high pressure drilling fluid exiting the horizontal
conduit to sweep the bottom of the tank, thereby providing a
more thorough cleaning action.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become
more apparent from the following description in which
reference is made to the appended drawings, the drawings are
for the purpose of illustration only and are not intended to
in any way limit the scope of the invention to a particular
embodiment or embodiments shown, wherein:
FIGURE 1 is a side elevation view, in section, of a floc
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tank equipped with an apparatus for preventing accumulations
of solids in a floc tank in accordance with the teachings of
the present invention.
FIGURE 2 is a top plan view of the floc tank illustrated
in FIGURE 1.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The preferred embodiment, an apparatus for preventing
accumulations of solids in a drilling fluid conditioning tank
generally identified by reference numeral 10, will now be
described with reference to FIGURES 1 and 2.
Structure and Relationship of Parts:
Referring to FIGURE 1, apparatus 10, includes a
combination of a floc tank 12, a centrifuge 14, and a high
pressure water agitation gun 16. Floc tank 12 has a bottom
18 and a peripheral sidewall 20. Centrifuge 14 is in fluid
communication with fluids in tank 12. High pressure water
agitation gun 16 is mounted in tank 12. Agitation gun 16 has
an outlet nozzle 22 positioned to direct a jet stream of high
pressure drilling fluid at bottom 18 of tank 12, whereby
solids accumulated on bottom 18 of tank 12 are fluidized for
removal by centrifuge 14. Agitation gun 16 has a vertical
conduit 24 with an axis 26 substantially parallel to
peripheral sidewall 20 of tank 12, and a substantially
horizontal conduit 28 positioned adjacent to bottom 18 of
tank 12. Referring to FIGURE 2, vertical conduit 24 is
mounted by mounting brackets 30 on peripheral sidewall 20
within tank 12 for rotation about its axis 26, such that
rotation of vertical conduit 24 causes jet stream of high
pressure drilling fluid exiting horizontal conduit 28 to
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sweep bottom 18 of tank 12.
Operation:
The operation of apparatus 10 in accordance with the
5 preferred method for preventing accumulations of solids in a
floc tank will now be described with reference to FIGURES 1
and 2.
Referring to FIGURE 1, to prevent accumulations of
solids, tank 12 is equipped with high pressure water
agitation gun 16, as described above. Accumulated solids are
fluidized by subjecting the accumulated solids to a jet
stream of high pressure drilling fluid from agitation gun 16.
Accumulated solids that have been fluidized are removed by
circulating the fluidized solids through centrifuge 14.
In this patent document, the word "comprising" is used
in its non-limiting sense to mean that items following the
word are included, but items not specifically mentioned are
not excluded. A reference to an element by the indefinite
article "a" does not exclude the possibility that more than
one of the element is present, unless the context clearly
requires that there be one and only one of the elements.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment
without departing from the spirit and scope of the invention
as hereinafter defined in the Claims.
