U.S. patent number RE32,866 [Application Number 06/936,537] was granted by the patent office on 1989-02-14 for method and apparatus for distributing fluids within a subterranean wellbore.
This patent grant is currently assigned to Chevron Research Company. Invention is credited to Don S. Cruise.
United States Patent |
RE32,866 |
Cruise |
February 14, 1989 |
**Please see images for:
( Certificate of Correction ) ** |
Method and apparatus for distributing fluids within a subterranean
wellbore
Abstract
A method and apparatus for distributing fluids within a
subterranean borehole wherein a submersible pump is introduced into
the borehole at a first location. An intake port of the pump is
connected to the first end of an intake duct having an unconnected
second end located at a second location within the wellbore from
which location fluid is to be withdrawn. An output port of the pump
is connected to a first end of a second duct having an unconnected
second end at a third location within the wellbore into which
location fluid is to be introduced. By activating the pump, fluids,
such as scale and corrosion inhibitors, are distributed from above
the intake of a production pump to as low in the borehole as is
required to protect wellbore contents.
Inventors: |
Cruise; Don S. (Buras, LA) |
Assignee: |
Chevron Research Company (San
Francisco, CA)
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Family
ID: |
27081201 |
Appl.
No.: |
06/936,537 |
Filed: |
November 26, 1986 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
591626 |
Mar 20, 1984 |
04580634 |
Apr 8, 1986 |
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Current U.S.
Class: |
166/310; 166/105;
166/312; 166/371 |
Current CPC
Class: |
E21B
37/06 (20130101); E21B 41/02 (20130101); E21B
43/00 (20130101); E21B 43/128 (20130101) |
Current International
Class: |
E21B
43/00 (20060101); E21B 37/06 (20060101); E21B
37/00 (20060101); E21B 41/02 (20060101); E21B
43/12 (20060101); E21B 41/00 (20060101); E21B
037/06 () |
Field of
Search: |
;166/68,68.5,105-112,244C,371,279,310,312,304,300,311,101,183,54,72 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Cruise et al., "Use of Continuous Coil Tubing for Subsurface Scale
and Corrosion Treating--Rangely Weber Sand Unit", SPE 11853,
Society of Petroleum Engineers of AIME, May 23-25, 1983, Dallas
Tex., 6 pages..
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Primary Examiner: Novosad; Stephen J.
Attorney, Agent or Firm: LaPaglia; S. R. Keeling; E. J.
Claims
What is claimed is:
1. Apparatus for distributing fluids around equipment including a
production pump to be protected within a subterranean borehole
comprising:
a submersible pump being positioned at a first location within the
borehole and having an intake port and an output port;
means, connected to said submersible pump, for activating said
submersible pump;
an intake duct having a first end connected to said intake port and
having a free second end at a second location within the borehole
for withdrawing fluid from the second location said second location
being on a first side of the equipment to be protected; and
an output duct having a first end connected to said output port and
having a free second end at a third location within the wellbore
for introducing fluids into the third location, said third location
being on a second side of the equipment to be protected, said
equipment to be protected including a production pump having an
intake and wherein said second location is above said intake and
wherein said third location is below said intake.
2. The apparatus as recited in claim 1 further comprising a casing
having perforations in a production zone and wherein said third
location is below said perforations.
3. The apparatus as recited in claim 1 wherein said output duct
comprises a tailpipe.
4. The apparatus as recited in claim 1 wherein said pump is a
single stage pump.
5. A method for distributing fluids within a subterranean borehole
around equipment to be protected comprising the steps of:
introducing into the borehole at a first location apparatus
comprising a submersible pump having an intake port connected to a
first end of an intake duct and having an output port connected to
a first end of an output duct;
positioning a free second end of said intake duct within the
borehole at a second location from which fluid is to be withdrawn,
the second location being on a first side of the equipment to be
protected;
locating a free second end of said output duct within the borehole
at a third location into which fluid is to be introduced, the third
location being on a second side of the equipment to be
protected;
activating said submersible pump; and
providing a treatment fluid to said second location, said treatment
fluid selected from the group consisting of a corrosion inhibitor,
scale inhibitor, a defoamer, an emulsion breaker, a focculant, a
paraffin inhibitor, a bactericide and mixtures thereof. .Iadd.
6. In a well installation, having casing, a string of tubing
extending to a downhole centrifugal pumping assembly, defining an
annulus between the casing and the tubing and pumping assembly, and
means at the surface for introducing inhibiting chemicals into the
annulus, the pumping assembly including a centrifugal primary pump
driven by an electrical motor located below the pump and separated
by a seal section for preventing well fluids from entering the
motor, the improvement comprising in combination:
a centrifugal secondary pump having an upper end adapted to be
connected to the bottom of the primary pump and a lower end adapted
to be connected to the top of the seal section;
the secondary pump having an intake port on its upper end adapted
to be connected to an intake tube that extends above an intake of
the primary pump, terminating in the annulus; and
the secondary pump having a discharge port on its lower end adapted
to be connected to a discharge tube that extends downwardly through
the annulus alongside the motor to a point in the annulus below the
motor, for pumping inhibiting chemicals drawn from the annulus to a
location below the motor, which then flow upwardly around the motor
and into the intake of the primary pump. .Iaddend. .Iadd.
7. Apparatus for introducing inhibiting chemicals into a wellbore
comprising:
(a) a production pump at a first location in the wellbore;
(b) a secondary pump at a second location within the wellbore
further comprising:
(i) an intake tube; and
(ii) a discharge tube;
(c) a motor for driving said production pump above discharge tube.
.Iaddend. .Iadd.
8. In a well installation, having casing, a string of tubing
extending to a downhole pumping assembly, defining an annulus
between the casing and the tubing and pumping assembly, and means
at the surface for introducing inhibiting chemicals into the
annulus, the pumping assembly including a primary pump driven by an
electrical motor located below the pump and separated by a seal
section for preventing well fluids from entering the motor, the
improvement comprising in combination:
a secondary pump having an upper end adapted to be connected to the
bottom of the primary pump and a lower end adapted to be connected
to the top of the seal section;
the secondary pump having an intake pump on its upper end adapted
to be connected to an intake tube that extends above an intake of
the primary pump, terminating in the annulus; and
the secondary pump having a discharge port on its lower end adapted
to be connected to a discharge tube that extends downwardly through
the annulus alongside the motor to a point in the annulus below the
motor, for pumping inhibiting chemicals drawn from the annulus to a
location below the motor, which then flow upwardly around the motor
and into the intake of the primary pump. .Iaddend. .Iadd.
9. Apparatus for introducing inhibiting chemicals into a wellbore
comprising:
(a) casing;
(b) tubing within the casing defining an annulus between the tubing
and the casing;
(c) a pumping assembly substantially at the end of said tubing and
further comprising:
(i) a primary pump;
(ii) an electrical motor for driving said primary pump; and
(iii) a seal section between said pump and said motor;
(d) a secondary pump having an upper end connected to the bottom of
said primary pump and a lower end connected to the top of said seal
section and further comprising:
(i) an inhibitor intake port connected to an intake tube operably
terminating in said annulus; and
(ii) a discharge port adapted to be connected to a discharge tube
extending downwardly through said annulus alongside said motor to a
point in said annulus below said motor. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention pertains in general to methods and apparatus
for distributing fluids within a subterranean wellbore and in
particular to methods and apparatus for distributing scale- or
corrosion-inhibiting substances within a wellbore.
Deposition of scale on and corrosion of production equipment within
a wellbore are severe problems in a number of oil fields. In some
areas, corrosion problems are so great that downhole equipment must
be pulled every few weeks for the purpose of replacement of damaged
components. Scale buildup may be so severe that downhole
submersible pump assemblies become insulated from the production
fluid, causing the motor to heat up and fail prematurely. In other
instances, scale buildup may be so severe that downhole components
become stuck in the hole, so that their removal requires a costly
fishing job.
One method of treatment for protecting well components involves
continuously flushing scale and corrosion inhibitors down the
annulus between production tubing and the well casing. Another
protection method involves introducing a packer between the casing
and the tubing above the production zone. Above the production
zone, the tubing-casing annulus is filled with corrosion-and
scale-inhibiting liquid. Neither of these techniques protects the
casing or elements of the production tubing string below the point
at which wellbore fluids are withdrawn into the production
tubing.
Scale and corrosion below the production tubing intake is
especially troublesome in deep wells where a downhole submersible
pump is used to move production fluids towards the surface.
Conventional methods of continuous flushing of scale and corrosion
inhibitors or employing a packed-off, scale and corrosion
inhibitor-filled annulus offer no protection to the seal and motor
commonly found below the pump intake. Thus, frequent pulling of the
well may be necessitated at great cost despite the use of scale and
corrosion inhibitors.
One approach to scale and corrosion protection below the pump
intake involves pumping scale and corrosion inhibitors from the
surface down 3/4 inch coiled mild steel tubing which follows the
production string and which attaches to a fiberglass tailpipe
extending from the lower surface of a motor at the end of the
production string to below the bottom of the production zone. This
technique is successful in protecting downhole components, but is
cumbersome, may require field-welding of lengths of tubing, and the
tubing itself is subject to corrosion problems.
SUMMARY OF THE INVENTION
Accordingly, the present invention involves apparatus for
distributing fluids, particularly corrosion and scale inhibitors,
within a subterranean wellbore. The apparatus according to the
present invention includes a submersible pump positioned at a first
location within the borehole. Means for activating the submersible
pump is connected to the pump. An intake port of the submersible
pump is connected to the first end of an intake duct which has a
second end for withdrawing fluids from a free second location
within the borehole. An output port of the submersible pump is
connected to a first end of an output duct which has a free second
end at a third location within the wellbore.
A method according to the present invention involves distributing
fluids within the subterranean wellbore and includes the steps of
introducing into the wellbore at a first location apparatus
comprising a submersible pump having an intake port connected to a
first end of an intake duct and having an output port connected to
a first end of an output duct. A free second end of the intake duct
is positioned within the wellbore at a second location from which
fluid is to be withdrawn. A free second end of the output duct is
located within the wellbore at a third location into which fluid is
to be introduced. The pump is then activated.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a view in partial cross-section of a preferred embodiment
of the present invention.
FIG. 2 is a partial cross sectional view illustrating an alternate
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the Figure, which illustrates the contents of a borehole in the
vicinity of a production zone, a submersible production pump 10 has
an input 16 and has an output connected to the end of a cylindrical
production tubing 12 within well casing 14.
A rotatable connection is provided between pump 10 and an inhibitor
pump 20. Inhibitor pump 20 is connected to the top end of a sealed
motor 24 by a rotatable shaft (not shown) through a seal 22. The
bottom of motor 24 is connected to a first end of a hollow,
cylindrical fiberglass stinger assembly 26 which has a free (i.e.,
unconnected) second end 38 above perforations 28 in casing 14.
A first length of coiled tubing 30 has a first end connected to an
intake port 32 of pump 20 and a free second end 31 above the top of
pump 10. A second length of coiled tubing 34 has a first end
connected to an output port 35 of pump 20 and has a second end
joined to tailpipe 26 at a junction 36.
An annulus .[.38.]. .Iadd.39 .Iaddend.formed between production
tubing 12 and the elements attached thereto and casing 14. Tubing
30 forms an intake duct having a free end 31 for withdrawing fluids
from the reservoir formed by annulus 38 above pump 10. Similarly,
tubing 34 in combination with tailpipe 26 having free end 38 forms
an output duct for introducing fluids into the reservoir formed by
the cavity within casing 14 and below motor 24.
Submersible pumps, such as pumps 10 and 20, are well known and
readily available to those skilled in the art. Pump 20 may be a one
stage pump readily available to those skilled in the art in the
form of a single stage of a commonly available multi-stage pump.
However, it is not intended that the present invention be limited
to a single stage pump. Seals, shafts and motors are well known and
readily available to those skilled in the art and will not be
discussed further. Three-quarter inch coiled mild steel tubing
suitable for use in the present invention is readily available from
a variety of sources, including NOWSCO, Houston, Tex. A fiberglass
tailpipe such as stinger assembly 26 is readily manufactured from
fiberglass tubing readily available to those skilled in the
art.
Scale inhibitor pump 20 may be bolted on in series between pump 10
and seal 22. Pump 20 may have the same diameter shaft as pump 10
and may be stabilized by a top bearing to avoid side play.
Tubing 30 and 34 may be round where the width of annulus 38.].
.Iadd.39 .Iaddend.permits and may be flattened where the annulus is
narrow. Free end 31 may have an attached filter or may merely be
plugged and have holes drilled in tubing 30 to provide
filtration.
Motor 24 may be electrically powered by means of a cable (not
shown) extending from the surface. In the embodiment illustrated in
the Figure inhibitor pump 20 is activated whenever motor 24 is
operating pump 10.
In the operation of the present invention, scale and corrosion
inhibitor fluid is pumped from the surface down annulus 39 as
indicated by arrow 40. Upon activation of pump 20, inhibitor is
withdrawn from annulus .[.38.]. .Iadd.39 .Iaddend.through tubing 30
into intake port 32 of pump 20. The inhibitor fluid is then pumped
from output port 35, through tubing 34, past junction 36 and out of
tailpipe 26. Fluid forced out of free end 38 of tailpipe 26 by the
action of pump 20 is pulled toward pump 10 along with formation
fluids passing into casing 14 through perforations 28 as indicated
by arrow 42.
Thus, scale and corrosion inhibitor fluids enter intake 16 of pump
10 from the surface and from below (mixed with production fluids).
In this way elements of the production string both above and below
intake 16 of pump 10 are protected, contrary to the condition found
in the prior art.
While the present invention has been described in terms of a
preferred embodiment, further modifications and improvements will
occur to those skilled in the art. For example, the precise
location of pump 20 in relation to pump 10, motor 24, and seal
.[.24.]. .Iadd.22 .Iaddend.is not critical so that variations in
the order of these elements along the production string are
intended to come within the scope of the invention as described.
Likewise, the illustrated position of the intake and output ports
of pump 20 are not meant to be restrictive and as is obvious to one
with mechanical skills in the art, these locations may be varied
according to the position of the ports on the particular pump used.
Similarly, free ends 38 may be positioned below perforations 28
where it is desirable to protect casing 14 around perforations 28
or to promote mixing of fluids prior to entering the pump intake
where desirable. Intake and output ducts may be varied in length
for the sake of convenience to the extent that they may comprise
the rims of or slight extensions of the input and output ports.
Furthermore, it is not intended that the present invention be
limited in its use to movement of scale or corrosion inhibitor
fluids. In fact, the scale inhibitor pump according to the present
invention may be used in wells with gas locking problems, may be
used to cool the motor of a low volume submersible pump located
below the perforations, and may be used to distribute a wide
variety of other treatment fluids and chemicals such as defoamers,
emulsion breakers, flocculants, paraffin inhibitors, bactericides,
and so forth, from and to various locations within a wellbore.
I desire it to be understood, therefore, that this invention is not
limited to the particular form shown and that I intend in the
appended claims to cover all such equivalent variations which come
within the scope of the invention as claimed.
* * * * *