Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR PRODUCING HYDROCARBONS
TECHNICAL FIELD
[0001] This relates to production of hydrocarbons from a well, in
particular using a
reciprocating string to stimulate production from the well.
BACKGROUND
[0002] Hydrocarbon wells can be stimulated to improve the efficiency of
hydrocarbon
production. U.S. Patent No. 3,520,362 entitled "Well Stimulation Method"
describes a method of
stimulating a well using acoustic vibrations.
SUMMARY
[0003] According to an aspect, there is provided a method of producing
hydrocarbons from a
well that has a production string positioned within a casing string. The
method may comprise the
steps of: providing a progressive cavity pump having a rotor, a stator, an
inlet in fluid
communication with the hydrocarbon producing formation, and an outlet in fluid
communication
with the production string; and while operating the progressive cavity pump,
stimulating the well
by reciprocating the stator of the progressive cavity pump and relative to the
casing string.
[0004] According to other aspects, the method may include one or more of
the following
features, alone or in combination: the rotor may be axially fixed relative to
the casing string such
that the stator is reciprocated along the rotor; the stator may be
rotationally fixed; the rotor may
reciprocate with the stator; one or more agitators may be provided that move
with the stator, the
agitators extending toward the casing string relative to the stator;
stimulating the well may
comprise generating pressure fluctuations in the hydrocarbon producing
formation or turbulence
in the casing string; the rotor of the progressive cavity pump may be at least
36 inches longer
than the stator of the progressive cavity pump; when the stator is in a raised
position relative to
Date Recue/Date Received 2020-08-14
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the rotor, the rotor of the progressive cavity pump may extend past a bottom
end of the rotor; the
stator may be reciprocated by a hydraulic actuator attached to the production
string; the stator of
the progressive cavity pump may be attached to the production string; and
reciprocating the
stator may comprise reciprocating the production string.
[0005] According to an aspect, there is provided an apparatus for producing
hydrocarbons
from a well that has a casing string. The apparatus may comprise a production
string adapted to
be inserted into the casing string, and a progressive cavity pump carried by
the production string.
The progressive cavity pump comprises a rotor, a stator, an inlet adapted to
be in fluid
communication with a hydrocarbon producing formation, and an outlet in fluid
communication
with the production string. One or more agitators are in a fixed position
relative to the stator, the
one or more agitators extending radially outward relative to the stator. An
actuator is provided
that is adapted to axially reciprocate the stator relative to the casing
string while the progressive
cavity pump is operating.
[0006] According to other aspects, the apparatus may comprise one or
more of the following
features, alone or in combination: the rotor may be axially fixed relative to
the casing string such
that the stator is reciprocated along the rotor; the stator may be
rotationally fixed relative to the
casing string; the rotor may reciprocate with the stator; the rotor of the
progressive cavity pump
may be at least 36 inches longer than the stator of the progressive cavity
pump; the actuator may
be at or above a wellhead of the well; the actuator may be a hydraulic
actuator; the one or more
agitators may be carried by the stator of the progressive cavity or the
production string; the one
or more agitators may comprise annular cups having a diameter sufficient to at
least partially
engage an inner surface of the casing string; and there may be a drive rod
that connects to the
rotor of the progressive cavity pump from a drive head at surface.
[0007] In other aspects, the features described above may be combined
together in any
reasonable combination as will be recognized by those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
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[0008] These and other features 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 be in any way limiting, wherein:
FIG. 1 is an elevated side view in cross section of an apparatus for producing
hydrocarbons.
FIG. 2 is an elevated side view in cross section of a well head of an
apparatus for
producing hydrocarbons in a raised position.
FIG. 3 is an elevated side view in cross section of a well head of an
apparatus for
producing hydrocarbons in a lowered position.
FIG. 4 is an elevated side view in cross section of a downhole portion of an
apparatus
for producing hydrocarbons with the stator in a raised position.
FIG. 5 is an elevated side view in cross section of a downhole portion of an
apparatus
for producing hydrocarbons with the stator in a lowered position.
FIG. 6 is an elevated side view in cross section of a downhole portion of an
apparatus
for producing hydrocarbons with the stator and rotor in a raised position.
FIG. 7 is an elevated side view in cross section of a downhole portion of an
apparatus
for producing hydrocarbons with the stator and rotor in a lowered position.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0009] An apparatus for producing hydrocarbons, generally identified by
reference numeral
10, will now be described with reference to FIG. 1 through 5.
[0010] Referring to FIG. 1, apparatus 10 is used to produce hydrocarbons
from a well 12 that
has a casing string 14 that forms the outer edge of well 12 and that has been
drilled into a
hydrocarbon producing formation 100.
[0011] Referring to FIG. 1, apparatus 10 has a production string 16 that
is adapted to be
inserted into casing string 14. Production string 16 may be inserted such that
it extends into
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hydrocarbon formation 100. A progressive cavity pump 20 is carried by
production string 16 and
adapted to be inserted into well 12. Progressive cavity pump 20 has a rotor
22, a stator 24, an
inlet 26, and an outlet 28. Inlet 26 is in fluid communication with
hydrocarbon producing
formation 100 and outlet 28 is in fluid communication with production string
16. Stator 24 may
be fixed to production string 16 using one or more connectors 25, as shown, or
stator 24 and
production string 16 may be attached together using other methods well known
in the art. Rotor
22 may be driven by a drive rod 30 that extends between a drive head 44 at
surface to rotor 22,
such as through production tubing 16 as shown. In one example, stator 24 may
be 10 ¨ 30 feet
long and rotor 22 may be at least 36 inches longer than stator 24; other
progressive cavity pump
20 dimensions may also be used.
[0012] Referring to FIG. 4 and FIG. 5, stator 24 is adapted to
reciprocate along the length of
rotor 22 while rotor 22 is rotated, where stator 24 moves relative to casing
string 14. Stator 24 is
preferably rotationally fixed relative to casing string 14, and rotor 22 is
preferably axially fixed
relative to casing string 14 as allowing movement of rotor 22 would require
additional
equipment. A bottom portion 13 of casing string 14 is open to allow
hydrocarbons to enter well
12 as is known in the art. Progressive cavity pump 20 is in communication with
fluid that enters
well 12 via bottom portion 13.
[0013] Apparatus 10 has one or more agitators 32 that extend radially
outward relative to
stator 24 and are fixed relative to stator 24. Agitators 32 may be carried by
one or both of
production string 16 and stator 24, or to a joint or tool installed between
production string 16 and
stator 24. In one example, shown in FIG. 4 and FIG. 5, agitators 32 may be
annular cups that
have a sufficient diameter to engage an inner surface of casing 14. The degree
to which cups 32
engage with casing 14 may be adjusted, and may be designed to be "leaky".
Agitators 32 may
take other forms, such as fins, flanges, etc., that may be designed to
accomplish different effects
downhole, depending on the characteristics of the well 12 and the type of well
stimulation
desired. For example, agitators 32 may be used to generate pressure
fluctuations between well 12
and downhole formation 100, or may be used to create turbulence in the
wellbore fluids within
casing 14.
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[0014] Referring to FIG. 2 and FIG. 3, apparatus 10 has an actuator 40
that axially
reciprocates stator 24 relative to rotor 22. Reciprocating stator 24 while
rotor 22 is rotating may
be used to generate turbulence within casing string 14. As shown, actuator 40
is connected to
production string 16, and reciprocates production string 16 and stator 24
together. As shown,
actuator 40 is attached above a well head 42 of well 12, however it will be
understood that
actuator may be located in other positions, such as partially or fully in well
14, or underground.
A drive head 44 for driving drive rod 30 may be connected above actuator 40.
Other components
may also be attached at well head 42 that are not shown, such as a blow-out
preventer, ports for
flow lines, or other equipment known in the art. Actuator 40 as depicted in
FIG. 2 and FIG. 3 is
one example of actuator 40; other variations may be possible, such as other
types of hydraulic or
mechanical actuators.
[0015] In the depicted example, actuator 40 may include a barrel 46, a
piston 48 within
barrel 46, and a cylinder ram 50 connected to piston 48 that extends out of
barrel 46 and is
connected to production string 16. Piston 48 may slide along a stationary tube
47 within barrel
46. Ram 50 may be connected to production string 16 by connectors 25.
Hydraulic power may
be provided through hydraulic ports 52 in barrel 46. As shown, a pipe 54 with
seals 56 may be
hung from well head 42 to isolate the top of production string 16 from gas
within casing string
14. One or more additional seals 56 may be used to seal barrel 46, piston 48,
production string
16, casing string 14, or other chambers not shown.
[0016] Referring to FIG. 6 and FIG. 7, in another example, actuator 40 may
reciprocate
stator 24 and rotor 22 together relative to casing string 14 as progressive
cavity pump 20
continues to operate. This may be contrasted to the example shown in FIG. 4
and FIG. 5, where
stator 24 reciprocates relative to rotor 22 and casing string 14. In this
manner, stator and 24 and
rotor 22 may be reciprocated to stimulate formation 100 while they are in the
same axial position
relative to each other. Stator 24 and rotor 22 may be reciprocated together by
mounting drive
head 44 to actuator 40, such that drive rod 30 and production string 16 are
reciprocated together.
In this case, rotor 22 would not have to be substantially longer than stator
24 as in FIG. 4 and
FIG. 5, but could be a similar size typical of progressive cavity pumps. As
with typical
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progressive cavity pumps, rotor 22 extends past the end of stator 24 although
variations may be
possible.
[0017] An example of a method of producing hydrocarbons from well 12
using apparatus 10
will now be described with reference to FIG. 2 to FIG. 7.
[0018] Apparatus 10 as described above is provided, and progressive cavity
pump 20 is
operated to produce fluid from hydrocarbon producing formation 100. Fluid
enters inlet 26 of
pump 20 and exits outlet 28 where it travels to well head 42 through
production string 16.
Progressive cavity pump 20 may be operated by driving rotor 22 with drive head
44 via drive rod
30. While progressive cavity pump 20 is being operated, stator 24 is
reciprocated relative to rotor
22 to stimulate well 12.
[0019] Stator 24 may be reciprocated by actuator 40 and may be
rotationally fixed while it is
being reciprocated. Rotor 22 may be axially fixed. Stator 24 is reciprocated
between a raised
position, such as shown in FIG. 4, and a lowered position, such as shown in
FIG. 5. The
corresponding raised and lower positions for actuator 40 is shown in FIG. 2
and FIG. 3,
respectively. If actuator 40 is connected to stator 24 via production string
16, production string
16 may be reciprocated as well. Stator 24 may be reciprocated such that at
least a portion of rotor
22 remains extends out of inlet 26.
[0020] In the example shown in FIG. 6 and 7, stator 24 and rotor 22 are
reciprocated
together between the raised position, as shown in FIG. 6, and the lowered
position, as shown in
FIG. 7. This may be accomplished by mounting stator 24 via production string
16 and rotor 22
via drive rod 30 to actuator 40.
[0021] In many situations, stator 24 may be reciprocated continuously,
or sufficiently
continuous to stimulate well 12. This may include controlling variables of the
reciprocation
pattern such as changes in speed or rest periods to achieve an acceptable
level of efficiency of
fluid production. Reciprocation may also be at a constant frequency for
extended periods of time.
For example, stator 24 may be reciprocated constantly outside of start up or
shut down
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procedures.
[0022]
Stimulation of well 12 is done to improve the ability of apparatus 10 to
produce
fluids from hydrocarbon formation 100, such as increasing fluid flow into well
12, keeping solids
suspended in fluid flowing through progressive cavity pump 20. Stimulation may
include
inducing turbulence in fluid within well 12, such as with agitators 32
attached to stator 24 or
production string 16. Rotor 22 may also contribute to stimulation of well 12
when rotor extends
out of stator 24, such as when stator 24 is in the raised position relative to
rotor 22 depicted in
FIG. 4. Stimulation may include generating pressure fluctuations within
hydrocarbon producing
formation 100, such as by using agitators 32 that are annular cups extending
between stator 24 or
production string 16 and casing string 14. Stimulation of well 12 is done to
improve the ability of
apparatus 10 to produce fluids from hydrocarbon formation 100, such as
increasing fluid flow
into well 12, or keeping solids suspended in the fluid.
[0023]
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 elements is present, unless the context clearly
requires that there be one
and only one of the elements.
[0024]
The scope of the following claims should not be limited by the preferred
embodiments
set forth in the examples above and in the drawings, but should be given the
broadest
.. interpretation consistent with the description as a whole.
Date Recue/Date Received 2020-08-14
