Note: Descriptions are shown in the official language in which they were submitted.
. . . . . . ... . . . i . ..... . ..... .. . .. . .. . . ..._ . . ._ . . .
CA 02644168 2008-11-18
AGITATOR TOOL FOR PROGRESSIVE CAVITY PUMP
Field of the Invention
This invention relates to an agitator tool for a progressive cavity pump.
Background of the Invention
Progressive cavity pumps have been used for decades to pump medium to high
viscosity fluids
commonly filled with solid particulate material (for example, sand, glass
beads, glass balloons
and metallic or organic fillers, i.e., quartz, aluminum oxide, and titanium
oxide) from an oil well
to the surface through a production tubing string. A typical progressive
cavity pump system
includes a surface drive and a downhole progressive cavity pump with a single
helical-shaped
rotor which turns eccentrically inside a double helical elastomer-lined
stator. The stator is
attached to the bottom of a production tubing string and, in most cases, the
rotor is .attached to a
rod string suspended and rotated by the surface drive. The shapes of the rotor
and stator form a
series of sealed cavities within the stator. As the rotor is turned, the
cavities progress to move
fluid from the intake to the discharge end of the pump, thereby producing a
pulsationless positive
displacement flow. The elastomer surface of the stator is intended to help the
pump handle
abrasive and viscous fluids. However, when a progressive cavity pump is
situated in a heavy oil
well, it is common for solid particulate material carried by heavy oil to plug
up the pump,
preventing further production from the well. Flushing of the pump is then
required, which
consumes time and delays production. Solid particulate material may also
contribute to the wear
and short operating life of parts, for example, the sta'tor.
Therefore, there is a need in the art for an apparatus which mitigates these
limitations.
Summary of the Invention
The present invention relates to an agitator tool for use in a progressive
cavity pump.
CA 02644168 2008-11-18
In one aspect, the invention provides a tool for use with a progressive cavity
pump for agitating a
slurry of sand, heavy oil or water comprising:
(a) an elongate body having a lower end, an upper end, and defining a
plurality of
longitudinal grooves spaced between the lower and upper ends and radially
about
the body;
(b) the upper end configured for coupling to a pump rotating element;
(c) a plurality of agitation members pivotally mounted within the longitudinal
grooves so as to be foldable from an actuation position wherein the agitation
members project outwardly from the body, to resting positions wherein the
agitation members are folded within the grooves during installation and
removal
of the tool; and
(d) biasing means for biasing the agitation members towards the actuation
position.
In one embodiment, the biasing means comprises springs through which cap
screws extend to
pivotally mount the agitation members within the longitudinal grooves.
In one embodiment, the cap screws are countersunk and threaded through aligned
bores defined
in opposing side walls of the longitudinal grooves.
In one embodiment, the springs are helical torsion springs, each having
attachment means at its
ends to secure the spring within the longitudinal groove at one end and to
attach the spring to the
agitation member at the other end.
In one embodiment, the agitation members are positioned in sets of pairs along
the length and
radially about the body.
In one embodiment, the agitation members are formed in the shape of a
rectangle having a notch-
like recess for receiving and accommodating the spring.
2
. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
CA 02644168 2008-11-18
In one embodiment, the upper end is externally threaded for connection with an
internally
threaded coupling at the bottom end of a rotating element.
In one embodiment, a horizontal, annular shoulder is formed by the body at a
junction of the
upper end and the body.
In one embodiment, the lower end has a flat, horizontal surface.
In one embodiment, the lower end may be tapered, pointed, conical, or beveled.
In one embodiment, the longitudinal grooves span a portion or substantially
the entire length of
the body between its ends.
In one embodiment, the longitudinal grooves are spaced intermittently and in
alignment along
the length of the body with a clearance between each groove.
Additional aspects and advantages of the present invention will be apparent in
view of the
description, which follows. It should be understood, however, that the
detailed description and
the specific examples, while indicating preferred embodiments of the
invention, are given by
way of illustration only, since various changes and modifications within the
spirit and scope of
the invention will become apparent to those skilled in the art from this
detailed description.
Brief Description of the Drawin2s
The invention will now be described by way of an exemplary embodiment with
reference to the
accompanying simplified, diagrammatic, not-to-scale drawings. In the drawings:
Figure 1 is a diagrammatic representation of a side sectional view of a
conventional, prior art
progressive cavity pump system.
Figure 2 is a diagrammatic representation of a side view of a tool of the
present invention.
3
. . .. . . .. . . . . ~. . . .. . ... . .. . . . . . . .
CA 02644168 2008-11-18
Figure 3 is a diagrammatic representation of a top view of a tool of the
present invention.
Figure 4 is a diagrammatic representation of a bottom view of a tool of the
present invention.
Figure 5 is a diagrammatic representation showing a side view of an agitation
member mounted
within a groove of the tool of Figure 1.
Figure 6 is a diagrammatic representation showing a side view of an agitation
member mounted
within a groove of the tool of Figure 1.
Figure 7a is a diagrammatic representation showing a side view of an agitation
member in the
upward resting position within a groove of the tool of Figure 6.
Figure 7b is a diagraxnmatic representation showing a side view of an
agitation member in the
downward resting position within a groove of the tool of Figure 6.
Figure 8 is a diagrammatic representation of a tool of the present invention
in an actaa.tion
position within a progressive cavity pump.
Detailed Description of Preferred Embodiments
When describing the present invention, all terms not defined herein have their
common art-
recognized meanings. To the extent that the following description is of a
specific embodiment or
a particular use of the invention, it is intended to be illustrative only, and
not limiting of the
claimed invention. The following description is intended to cover all
alternatives, modifications
and equivalents that are included in the spirit and scope of the invention, as
defined in the
appended claims.
The present invention provides an agitator tool for use in a progressive
cavity pump. A
conventional prior art progressive cavity pump (1) for a production well is
shown in Figure 1
(Weatherford, TX, U.S.A.). The components include, sequentially from the top
to bottom, a
4
CA 02644168 2008-11-18
vertical electric wellhead drive (2), casing (3), production tubing (4),
sucker rod (5), tubing
collars (6), stator (7), rotor (8) and tag bar sub (9). The agitator tool of
the present invention
connects to the bottom end of a standard rotor, and agitates solid particulate
material (for
example, sand) and oil into a slurry which can easily be pumped. Agitation or
mixing of the
solid particulate material and oil prevents such materials from clumping and
blocking the inflow
to the progressive cavity pump, and helps with gas breakout by agitating the
gas pockets mixed
with the solid particulate material and oil. The tool is suitable for handling
any type of fluid and
abrasive compound or sand mixture, or simply fluid and gas.
The tool (10) is generally shown in Figure 2 to include an elongate body (12)
having an upper
end (14), a lower end (16), and defining a plurality of longitudinal grooves
(18) spaced between
the upper and lower ends (14, 16) and radially about the body (12).
The dimensions of the tool (10) are not essential to the invention and are
dictated by the size of
the pump (1) and the production tubing (4). Typically, the body (12) of the
tool (10) may be in
the range of 1 to 5 feet in length in a longitudinal direction of the
production tubing string and
have a diameter in the range of 2" to 6". The body (12) of the tool (10) may
have a diameter
which is the same or smaller than the diameter of the stator (7).
The upper end (14) is configured for coupling to a pump rotating element (not
shown) to provide
for rotation of the rotating element (not shown) and the body (12) of the tool
(10) about a
common axis. In one embodiment, the upper end (14) is externally threaded for
connection with
an interna.lly threaded coupling at the bottom end of the rotating element, as
shown in Figures 2
and 3. A horizontal, annular shoulder (20) is formed by the body (12) at the
junction of the
upper end (14) and body (12) portions. Other suitable connection means to
allow the tool (10) to
be installed or released from the rotating element are well known to those
skilled in the art such '
as, for example, screw-on couplings and shear pins.
It will be understood by those skilled in the art that if desired, the tool
(10) can be permanently
attached to the rotating element by welding or other known techniques if the
tool (10) is to be
used regularly or solely in a particular well.
5
CA 02644168 2008-11-18
The lower end (16) is configured to be suspended above the bottom of the well.
In one
embodiment, the lower end (16) has a flat, horizontal surface, as shown in
Figure 4. In other
embodiments, the lower end (16) maybe, for example, tapered, pointed, conical,
or beveled.
The longitudinal grooves (18) are spaced between the upper and lower ends (14,
16) and radially
about the body (12). The grooves (18) may span a portion or substantially the
entire length of
the body (12) between its ends (14, 16). In one embodiment, the grooves (18)
are spaced
intermittently and in alignment along the length of the body (12), with a
clearance (22) between
each groove (18), as shown in Figure S. The grooves (18) are of sufficient
lengths to
accommodate agitation members (24) in both the upward and downward resting
positions. In
one embodiment, the grooves (18) are at least twice the length of an agitation
member (24). The
grooves (18) are formed within the surface (26) of the body (12) by machining
or other known
techniques.
The agitation members (24) are pivotally mounted within the grooves (18) to
enable three
positions of movement, namely an actuation position, an upward resting
position, and a'
downward resting position. The agitation members (24) are movable from the
actuation position
wherein the agitation members project outwardly from the body (12) during
rotation to agitate
the slurry, to the resting positions wherein the agitation members (24) are
folded within the
grooves (18) during installation or removal of the tool (10).
The agitation members (24) are normally biased by biasing means towards an
actuation position
(Figures 2-6 and 8). As used herein and in the claims, the term "actuation
position" refers to the
agitation members (24) projecting outwardly from the body (12) at an angle
sufficient to enable
agitation of solid particulate material when the body is rotated. The angle
may range from
approximately 20 to 90 . In one embodiment, the agitation members (24) may
project
outwardly from the body (12) at an initial angle ranging from approximately 20
to 45 , with the
angle gradually reaching approximately 90 (i.e., the agitation members
positioned in a
substantially horizontal orientation) as the speed of rotation increases
during operation. In one
6
. . ... . . . . . . .
CA 02644168 2008-11-18
embodiment, the agitation members (24) are positioned in sets of pairs along
the length and
radially about the body (12), as shown in Figure 4.
Figures 5 and 6 illustrate the biasing means as comprising a spring (28)
through which a cap
screw (30) extends to pivotally mount the agitation member (24) within the
groove (18). The
cap screw (30) is countersunk and threaded through aligned bores (32, 34)
defined in the
opposing side walls (36, 38) of the groove (18). In one embodiment, the spring
(28) is a helical
torsion spring having a hook, eye or other suitable attachment means at its
ends to secure the
spring (28) within the gruove (18) at one end, and to attach the spring (28)
to the agitation
member (24) at the other end.
The biasing means permits the agitation members (24) to fold into the grooves
(18) either
upwardly for installation into the well or downwardly for removal from the
well in a controlled
manner. As the tool (10) is being installed into the well, the agitation
members (24) are folded
into the grooves (18) upwardly for installation into the well (i.e., the
upward resting position as
shown in Figure 7a). As the tool (10) is retrieved from the well, the
agitation members (24) are
folded into the grooves (18) downwardly for removal from the well (i.e., the
downward resting
position as shown in Figure 7b).
The agitation members (24) may comprise various shaped projections such as
bars, blades, fins,
beveled paddles, or the like. Other shapes such as, for example, round, flat,
octagonal, or
triangular, may be appropriate. In one embodiment, the agitation member (24)
is formed in the
shape of a rectangle having at one end, a notch-like recess (40) which
receives and
accommodates the spring (28) when the agitation member (24) is mounted within
the groove
(18), as shown in Figure 6. The agitation members (24) are sized to fit within
the grooves (18).
The dimensions of the agitation members (24) are thus dictated by the size of
the grooves (18).
The tool (1) can be constructed from any material or combination of materials
having suitable
properties such as, for example, mechanical strength, ability to withstand
cold and adverse field
conditions, corrosion resistance, and ease of machining. In one embodiment,
the body (12) and
agitation members (24) are formed of steel, for example, stainless steel and
4140 alloy steel. In
7
CA 02644168 2008-11-18
one embodiment, the body (12) and agitation members (24) are formed of
aluminum or other
appropriate materials known to those skilled in the art. The springs (28) may
be formed of wire,
rubber or metal. The cap screws (30) may be formed of steel, for example,
stainless steel, and
strength-bearing materials.
The operation of progressive cavity pumps is commonly known to those skilled
in the art and
will not be discussed in detail. A typical progressive cavity pump (1) is
mounted within the well
tubulars, for example, the production casing (3) of a conventional well. As
shown in Figure 8,
the components include, sequentially from the top to bottom, a vertical
electric wellhead drive
(2), casing (3), production tubing (4), stator (7) and rotor (8). During
installation of the tool (10),
the tag bar sub (9, see Figure 1) is removed. An oversized coupling (42) is
welded to allow tag
or contact on the rotating element (i.e., the rotor (8)). The upper end (14)
of the tool (10) is
connected to the bottom end of the rotating element (8). The rotating element
(8) and connected
tool (10) are then fed through the stator (7) to a depth at which the lower
end (16) of the tool (10)
is placed within the formation. As the tool (10) is being fed downwardly into
the well, the
agitation members (24) fold upwardly into the grooves (18) in the resting
position, thereby
facilitating installation. Once the tool (10) has reached its operating
position, below the stator
(7), the agitation members are urged outward to their actuation position due
to the operation of
the springs (28).
In operation, the tool (10) is rotated with the rotating element (8) of the
pump. As the rotating
element reaches 100 to 300 rpm, the springs (28) hold the agitation members
(24) in the
actuation position to agitate solid particulate material and production fluid
(i.e., oil) into a slurry
which can be easily drawn from the well to the surface. Centrifugal force may
also contribute to
the agitation members being drawn into their actuation position. The agitation
members (24)
also facilitate gas breakout by agitating the gas pockets mixed with the solid
particulate material
and oil. As the rotating element (8) and tool (10) are lifted upwardly from
the well following
production, the agitation members (24) fold downwardly into the grooves (18)
in the resting
position, thereby facilitating removal from the well.
8
CA 02644168 2008-11-18
Importantly, installation or removal of the tool (10) (together with the
rotating element attached
to the upper end (14) of the tool (10)) is enabled by the spring-loading of
the agitation members
(24). The tool (10) can be readily connected or detached from a rotating
element for inspection,
reinsertion or replacement if necessary.
As will be apparent to those skilled in the art, various modifications,
adaptations and variations
of the foregoing specific disclosure can be made without departing from the
scope of the
invention claimed herein.
9
