U.S. patent number 3,802,802 [Application Number 05/154,415] was granted by the patent office on 1974-04-09 for pump system.
Invention is credited to F. Conrad Greer.
United States Patent |
3,802,802 |
Greer |
April 9, 1974 |
PUMP SYSTEM
Abstract
A pumping system employs the method of using an inoffensive
fluid as a displacing fluid to pump an offensive fluid to be
displaced. The system is illustrated in a well pumping operation
and includes a pump structure for establishing a moving fluid
interface between the displacing fluid and the well fluid to be
displaced from the well reservoir so that the displacing fluid
functions as a piston to pump well fluid to well surface. A gas
elimination system and a diluent injection system may be associated
with the pump structure to remove gas evolved from the well fluid
and to inject a diluent into the well fluid reservoir to reduce
well fluid viscosity.
Inventors: |
Greer; F. Conrad (Santa Maria,
CA) |
Family
ID: |
22551274 |
Appl.
No.: |
05/154,415 |
Filed: |
June 18, 1971 |
Current U.S.
Class: |
417/98; 417/385;
417/313; 417/431 |
Current CPC
Class: |
F04B
53/141 (20130101); F04B 47/02 (20130101) |
Current International
Class: |
F04B
47/00 (20060101); F04B 53/14 (20060101); F04B
53/00 (20060101); F04B 47/02 (20060101); F09b
035/02 () |
Field of
Search: |
;417/92,99,101-103,323,388,324,313,431,98 ;166/105.5,105.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Assistant Examiner: Smith; Leonard
Attorney, Agent or Firm: Huebner & Worrel
Claims
I claim:
1. In a down hole well pumping system, the improvement
comprising:
pump structure for positioning in a well bore down hole in contact
with a well reservoir, said pump structure defining a first fluid
confining chamber for receiving displacing fluid, a second fluid
confining chamber for receiving well fluid and a fluid conducting
passage interconnecting said fluid confining chambers in
communication with each other, said second chamber having an inlet
and outlet port defined therein, said inlet port being defined to
communicate with the well reservoir in which said pump structure is
positioned, said passage extending upwardly from its point of
communication with said second chamber to define an upwardly
extending channel of predetermined length in which displacing fluid
and well fluid may interface, at least a portion of said first
chamber defining a plunger chamber;
inlet valve means mounted in said inlet port for conducting well
fluid into said second chamber;
outlet valve means mounted in said outlet port for discharging
fluid from said second chamber;
means for expanding and contracting the effective volume of said
first chamber, each expansion and contraction of the effective
volume of said first chamber being defined as a pump stroke, said
means for expanding and contracting the effective volume of said
first chamber being a plunger means mounted for reciprocal motion
in said plunger chamber;
means for supplying displacing fluid to said pump structure on each
stroke of said pump at a controllable rate to maintain the moving
interface region between displacing fluid and well fluid within
said upwardly extending channel and said second chamber, said
displacing fluid supply means being operable to supply displacing
fluid to said pump structure in time coincidence with the expansion
of the effective volume of said first chamber;
said displacing fluid supply means comprising: reservoir means for
displacing fluid defined as a continuation of said plunger chamber,
said plunger means sealing said first chamber from said reservoir
means whereby movement of said plunger means to contract and expand
the effective volume of said first chamber, respectively, expands
and contracts the volume of said reservoir means; means connected
to said reservoir means for transferring displacing fluid thereto
at a controlled rate; and valve means mounted in said plunger means
for controlling the flow of displacing fluid between said reservoir
means and said first chamber, said valve means being operated by
the pressure differential developed between said first chamber and
said reservoir means to open and close, respectively, during the
expansion and contraction of the effective volume of said first
chamber; and
means for conducting fluid pumped from said outlet valve means to
well surface.
2. In a down hole well pumping system, the improvement
comprising:
pump structure for positioning in a well bore down hole in contact
with a well reservoir, said pump structure defining a first fluid
confining chamber for receiving displacing fluid, a second fluid
confining chamber for receiving well fluid and a fluid conducting
passage interconnecting said fluid confining chambers in
communication with each other, said second chamber having an inlet
and outlet port defined therein, said inlet port being defined to
communicate with the well reservoir in which said pump structure is
positioned, said passage extending upwardly from its point of
communication with said second chamber to define an upwardly
extending channel of predetermined length in which displacing fluid
and well fluid may interface, at least a portion of said first
chamber defining a vertically extending plunger chamber;
inlet valve means mounted in said inlet port for conducting well
fluid into said second chamber;
outlet valve means mounted in said outlet port for discharging
fluid from said second chamber;
means for expanding and contracting the effective volume of said
first chamber, said means for expanding and contracting the
effective volume of said first chamber is a plunger means mounted
for up and down reciprocal motion in said plunger chamber;
means for supplying displacing fluid to said pump structure at a
controllable rate to maintain the moving interface region between
displacing fluid and well fluid within said upwardly extending
channel and said second chamber, said displacing fluid supply means
being operable to supply displacing fluid to said pump structure in
time coincidence with the expansion of the effective volume of said
first chamber;
said displacing fluid supply means comprising: reservoir means for
displacing fluid defined as a continuation of said plunger chamber,
said plunger chamber being positioned above said reservoir means,
said plunger means sealing said first chamber from said reservoir
means whereby movement of said plunger means to contract and expand
the effective volume of said first chamber, respectively, expands
and contracts the volume of said reservoir means; means connected
to said reservoir means for transferring displacing fluid thereto
at a controlled rate; and valve means mounted in said plunger means
for controlling the flow of displacing fluid between said reservoir
means and said first chamber, said valve means being operated by
the pressure differential developed between said first chamber and
said reservoir means to open and close, respectively, during the
expansion and contraction of the effective volume of said first
chamber; and
means for conducting fluid pumped from said outlet valve means to
well surface.
3. The invention defined in claim 2, including a string of sucker
rods for reciprocating said plunger means up and down, said sucker
rods being connected to said plunger means and extending therefrom
to well surface, said sucker rods being hollow and defining a
conduit for conducting displacing fluid from well surface to said
plunger means, said plunger means having a fluid conducting path
defined therethrough for conducting displacing fluid from said
sucker rods to said reservoir means.
4. A well pumping system, comprising:
a sucker rod string;
a fluid sealed string of tubing for positioning in a well to extend
from the bottom portion of a well to well surface, said sucker rod
string being mounted in said string of tubing for reciprocation up
and down therein whereby said tubing functions as a housing to
isolate said sucker rod string from well fluid thereby up and down
reciprocal movement of said sucker rod string is not inhibited by
well fluid;
pump structure mounted on the lower end of said string of tubing to
depend therefrom into the reservoir of well fluid to be pumped,
said pump structure defining a first fluid confining chamber in
communication with a second fluid confining chamber through a fluid
conducting passage, said first and second chambers being for
holding, respectively, a displacing fluid and a well fluid, said
passage extending upwardly from its point of communication with
said second chamber to define an upwardly extending channel in
which displacing fluid and well fluid may interface, said second
chamber having inlet and outlet port means operable only to receive
and discharge fluid, respectively;
plunger means mounted for up and down reciprocal motion in said
first chamber for expanding and contracting the effective volume of
said first chamber to displace up and down in said channel the
region of interface between the displacing fluid and the well fluid
whereby the displacing fluid functions as a piston to pump well
fluid in said inlet port means and out said discharge port
means;
means for isolating the discharge point of said outlet port means
of said pump structure from the well fluid reservoir and connecting
said outlet port means in communication with well surface so that
well fluid discharged from said outlet port means is pumped to well
surface;
means for connecting said plunger means to said sucker rod string
whereby said plunger means may be driven through said sucker rod
string;
displacing fluid supply means connected to said first chamber for
supplying displacing fluid thereto at a controllable rate to
maintain the moving region of interface between the displacing
fluid and the well fluid within said upwardly extending channel and
said second chamber, said displacing fluid supply means being
operable to supply displacing fluid to said pump structure in time
coincidence with the expansion of the effective volume of said
first chamber;
said displacing fluid supply means comprising: structure defining a
reservoir for displacing fluid, said displacing fluid reservoir
being defined by a downwardly extending continuation of said first
chamber and being in alignment with said plunger means; means
connected to said displacing fluid reservoir for transferring
displacing fluid thereto at a controlled rate; and valve means
connecting said displacing fluid reservoir in communication with
said first chamber for controlling the flow of displacing fluid
between said displacing fluid reservoir and said first chamber,
said valve means being operable to open and close, respectively, in
time coincidence with the expansion and contraction of the
effective volume of said first chamber, said valve means being
operated by the pressure differential developed between said first
chamber and said displacing fluid reservoir during the expansion
and contraction of the effective volume of said first chamber;
said plunger means sealing said first chamber from said displacing
fluid reservoir whereby the up and down reciprocal movement of said
plunger means to contract and expand the effective volume of said
first chamber, respectively, expands and contracts the volume of
said reservoir means, said valve means being carried by said
plunger means; and
prime mover means connected to said sucker rod string for driving
said sucker rod string in up and down reciprocal motion thereby to
drive said plunger means.
5. The invention defined in claim 4, wherein:
said sucker rods are hollow and define a conduit for conducting
displacing fluid from well surface to said plunger means; and
said plunger means has a fluid conducting path defined therethrough
for conducting displacing fluid from said sucker rods to said
displacing fluid reservoir.
6. The invention defined in claim 4, wherein said means for
isolating the discharge point of said outlet port means of said
pump structure from the well fluid reservoir and connecting said
outlet port means in communication with well surface is a string of
production tubing detachably coupled to said outlet port means.
7. The invention defined in claim 4, wherein:
said sucker rod string defines a conduit for conducting displacing
fluid from well surface to said plunger means; and
said plunger means has a fluid conducting path defined therethrough
for conducting displacing fluid from said sucker rod string to said
reservoir means.
8. The invention defined in claim 7, wherein said means for
isolating the discharge point of said outlet port means of said
pump structure from the well fluid reservoir and connecting said
outlet port means in communication with well surface is a string of
production tubing detachably coupled to said outlet port means.
9. A pump for down hole use, comprising:
structure defining a first fluid confining chamber for receiving
displacing fluid, a second fluid confining chamber for receiving
well fluid and a fluid conducting passage interconnecting said
fluid confining chambers in communication with each other, said
second chamber having an inlet and outlet port defined therein,
said inlet port being defined to communicate with a well reservoir,
said passage extending upwardly from its point of communication
with said second chamber to define an upwardly extending channel of
predetermined length in which displacing fluid and well fluid may
interface, at least a portion of said first chamber defining a
plunger chamber;
inlet valve means mounted in said inlet port for conducting well
fluid into said second chamber;
outlet valve means mounted in said outlet port for discharging
fluid from said second chamber;
reservoir means defined as a continuation of said plunger chamber,
said reservoir means being arranged for connection to a displacing
fluid supply so that displacing fluid may be selectively supplied
thereto;
plunger means mounted for reciprocal motion in said plunger chamber
for expanding and contracting the effective volume of said first
chamber, said plunger means sealing said first chamber from said
reservoir means whereby movement of said plunger means to contract
and expand the effective volume of said first chamber,
respectively, expands and contracts the volume of said reservoir
means; and
valve means mounted in said plunger means for controlling the flow
of displacing fluid between said reservoir means and said first
chamber, said valve means being operated by the pressure
differential developed between said first chamber and reservoir
means to open and close, respectively, during the expansion and
contraction of the effective volume of said first chamber.
10. The invention defined in claim 9, wherein:
said plunger chamber is defined to be substantially vertically
extending; and
said reservoir means is defined as a downward continuation of said
plunger chamber.
11. The invention defined in claim 10, wherein:
said plunger means is arranged for connection to a string of
upwardly extending hollow sucker rods whereby sand plunger means
may be driven up and down and displacing fluid may be conducted
from well surface to said plunger means through a string of hollow
sucker rods connected thereto; and
said plunger means has a fluid conducting path defined therethrough
for conducting displacing fluid to said reservoir means from the
point of connection of a string of hollow sucker rods thereto.
12. The invention defined in claim 11, wherein said outlet port is
arranged for being detachably coupled to a string of production
tubing.
13. The invention defined in claim 9, wherein said outlet port is
arranged for being detachably coupled to a string of production
tubing.
14. A pump for downhole use to pump well fluid from a well, said
pump comprising:
structure defining a first fluid confining chamber in communication
with a second fluid confining chamber through a fluid conducting
passage, said first and second chambers being for holding,
respectively, a displacing fluid and a well fluid, said passage
extending upwardly from its point of communication with said second
chamber to define an upwardly extending channel in which displacing
fluid and well fluid may interface, said second chamber having
inlet and outlet port means operable only to receive and discharge
fluid, respectively, said pump structure having a gas trap defined
therein above and in communication with the upper end of said
channel to trap gas evolved from the well fluid, and including
valve controlled conduit means connected for conducting trapped gas
from said gas trap to a point in said second chamber adjacent said
outlet port means so that the gas is pumped out of said second
chamber with well fluid, said valve controlled conduit means being
operable to control the flow of gas therethrough as a function of
the pressure level of gas being conducted therethrough and the
pressure levels within said gas trap and said second chamber;
means for injecting displacing fluid at a controlled rate into said
first chamber, said means arranged for connection to a source of
displacing fluid;
means for expanding and contracting the effective volume of said
first chamber to displace up and down in said channel the region of
interface between the displacing fluid and the well fluid whereby
the displacing fluid functions as a piston to pump well fluid in
said inlet port means and out said discharge port means, said means
being constructed for connection with a prime mover; and
means for conducting fluid pumped from said outlet port means to
well surface.
15. The invention recited in claim 14, wherein said inlet port
means includes a check valve operative to prevent fluid flow
therethrough out from said second chamber and said outlet port
means includes a check valve operative to prevent fluid flow
therethrough into said second chamber.
16. The invention recited in claim 14, including means for
supplying displacing fluid, said displacing fluid supply means
being connected to said fluid injecting means to maintain the
region of interface between the displacing fluid and the displaced
fluid within said channel and second chamber.
17. The invention recited in claim 14, wherein said means for
expanding and contracting the effective volume of said first
chamber is a plunger means mounted therein for up and down
reciprocal motion, said plunger means being adapted for connection
through a string of sucker rods to a prime mover.
18. The invention recited in claim 14, including fluid injection
means associated with said structure to extend into well fluid
being pumped for injecting controlled quantities of a diluent fluid
into the well fluid to be pumped whereby to dilute and thereby
reduce the viscosity of the well fluid.
19. The invention recited in claim 14, wherein said means for
expanding and contracting the effective volume of said first
chamber is a plunger means mounted therein for reciprocal
motion.
20. The invention recited in claim 19, including prime mover means
connected to said plunger means for driving said plunger means in
its reciprocal path of motion.
21. A well pumping system, comprising:
a sucker rod string;
a fluid sealed string of tubing for positioning in a well to extend
from the bottom portion of a well to well surface, said sucker rod
string being mounted in said string of tubing for reciprocation up
and down therein whereby said tubing functions as a housing to
isolate said sucker rod string from well fluid thereby up and down
reciprocal movement of said sucker rod string is not inhibited by
well fluid;
pump structure mounted on the lower end of said string of tubing to
depend therefrom into the reservoir of well fluid to be pumped,
said pump structure defining a first fluid confining chamber in
communication with a second fluid confining chamber through a fluid
conducting passage, said first and second chambers being for
holding, respectively, a displacing fluid and a well fluid, said
passage extending upwardly from its point of communication with
said second chamber to define an upwardly extending channel in
which displacing fluid and well fluid may interface, said second
chamber having inlet and outlet port means operable only to receive
and discharge fluid, respectively, said pump structure having a gas
trap defined therein above and in communication with the upper end
of said channel to trap gas evolved from the well fluid, and
including valve controlled conduit means connected for conducting
trapped gas from said gas trap to a point in said second chamber
adjacent said outlet port means so that the gas is pumped out of
said second chamber with well fluid, said valve controlled conduit
means being operable to control the flow of gas therethrough as a
function of the pressure level of gas being conducted therethrough
and the pressure levels within said gas trap and said second
chamber;
plunger means mounted for up and down reciprocal motion in said
first chamber for expanding and contracting the effective volume of
said first chamber to displace up and down in said channel the
region of interface between the displacing fluid and the well fluid
whereby the displacing fluid functions as a piston to pump well
fluid in said inlet port means and out said outlet port means;
means for isolating the discharge point of said outlet port means
of said pump structure from the well fluid reservoir and connecting
said outlet port means in communication with well surface so that
well fluid discharged from said outlet port means is pumped to well
surface;
means for connecting said plunger means to said sucker rod string
whereby said plunger means may be driven through said sucker rod
string;
displacing fluid supply means connected to said first chamber for
supplying displacing fluid thereto at a controllable rate to
maintain the moving region of interface between the displacing
fluid and the well fluid within said upwardly extending channel and
said second chamber; and
prime mover means connected to said sucker rod string for driving
said sucker rod string in up and down reciprocal motion thereby to
drive said plunger means.
22. The invention recited in claim 21, wherein the well fluid is of
an offensive nature and the displacing fluid is of an inoffensive
nature.
23. The invention defined in claim 21, including lubricating fluid
within said fluid sealed string of tubing to provide a lubricated
path through which said sucker rod string may reciprocate with
minimum wear and substantially free fall velocity.
24. The invention recited in claim 21, wherein the well fluid is a
high viscosity crude oil, the displacing fluid is kerosene, and
including fluid injection means associated with said pump structure
to extend into the crude oil being pumped for injecting controlled
quantities of a diluent fluid into the high viscosity crude oil
whereby to dilute the crude oil and reduce its viscosity.
25. The invention recited in claim 24, wherein the diluent fluid is
kerosene.
26. The invention defined in claim 21, wherein said means for
isolating the discharge point of said outlet port means from the
well fluid reservoir and connecting said outlet port means in
communication with well surface is a fluid sealed string of
production tubing.
27. The invention defined in claim 26, wherein said string of
production tubing is detachably coupled to said pump structure.
28. The invention defined in claim 21, wherein said displacing
fluid supply means is operable to supply displacing fluid to said
pump structure in time coincidence with the expansion of the
effective volume of said first chamber.
29. The invention defined in claim 28, wherein said displacing
fluid supply means comprises:
structure defining a reservoir for displacing fluid;
means connected to said displacing fluid reservoir for transferring
displacing fluid thereto at a controlled rate; and
valve means connecting said displacing fluid reservoir in
communication with said first chamber for controlling the flow of
displacing fluid between said displacing fluid reservoir and said
first chamber, said valve means being operable to open and close,
respectively, in time coincidence with the expansion and
contraction of the effective volume of said first chamber.
30. The invention defined in claim 29, wherein said valve means is
operated by the pressure differential developed between said first
chamber and said displacing fluid reservoir during the expansion
and contraction of the effective volume of said first chamber.
31. The invention defined in claim 30, wherein:
said displacing fluid reservoir is defined by a downwardly
extending continuation of said first chamber, said displacing fluid
reservoir being in alignment with said plunger means; and
said plunger means seals said first chamber from said displacing
fluid reservoir whereby the up and down reciprocal movement of said
plunger means to contract and expand the effective volume of said
first chamber, respectively, expands and contracts the volume of
said reservoir means; and
said valve means is carried by said plunger means.
Description
BACKGROUND OF THE INVENTION
The present invention relates to pumps and pumping methods and more
particularly to a pump and pumping method suitable for use in
downhole well pumping operations, such as oil well pumping
operations, as well as in other pumping operations.
Heretofore, various types of pumps have been devised for pumping
well fluids, such as crude oils. Unfortunately, the crude oil
pumped is oftentimes of an extremely offensive nature containing
various impurities such as sand, silt, sludge, and salt water so as
to be abrasive and/or corrosive. A problem common with the design
of many of these prior art pumps has been that they have included
moving parts, such as plunger mechanisms, which contacted the
offensive fluids being pumped. Thus, as a consequence, the
offensive crude oils or well fluids have generally caused
considerable wear, excessive friction, and corrosion of the parts,
particularly the moving parts, of the prior art pumps. Considerable
expense, therefore, has generally been associated with the use of
these prior art pumps in such well pumping operations where an
offensive well fluid is being pumped since the pumps had to be
frequently shut down, removed from their downhole locations, and
rebuilt or repaired to change and replace their worn and/or
corroded moving parts.
Additionally, many prior art pumps constructed for well pumping
operations have been designed so that the displacing well fluid is
caused to move upward in physical contact with a reciprocating
sucker rod string. Unfortunately, the contact of the well fluid
which was generally of a high viscosity with the sucker rod string
acted to restrict the downward movement, so called rod fall, of the
sucker rod string, and thereby severely restricted the upper cycle
rate at which the plunger could be driven in these pumps to pump
well fluid to the well surface. Further, substantial stress was
placed on the sucker rod string by the downward movement of a
pumping jack to which it was connected since the upward flowing
well fluid resisted the sucker rod string's downward movement.
Consequently, pump outputs prior to this time have been limited
since it has not been possible to exceed rod fall rates greater
than approximately three strokes per minute without running the
danger of breaking the sucker rod string.
Other problems common with prior art downhole well pumps have been
that they have been subject to being locked up by gas locks caused
by gas evolved from the pumped well fluid and by the paraffin
occurring in paraffin based crude oils. Additionally, prior art
pumps have been unsuitable to pump extremely high viscosity crude
oil mixtures, such as sand laden crude oils, since in order to
avoid excessive wear from contact with the high viscosity well
fluids filtering mechanisms were employed to filter the impurities
from the oil and these filters unfortunately restricted to a
significant extent oil flow into the pump.
SUMMARY OF THE INVENTION
It is, accordingly, an object of the present invention to provide
an improved pump which is suitable for employing a displacing fluid
of an inoffensive nature to pump an offensive fluid thereby to
limit the contact of movable pump parts with the offensive fluid so
as to substantially reduce friction, pump wear, and pump
corrosion.
It is further an object of the present invention to provide an
improved pump suitable for downhole use which is operable to
establish and maintain an interface between a displacing fluid and
a fluid to be displaced and to displace this interface in a
reciprocal motion so that the displacing fluid functions at the
interface as a piston to prevent gas lock and pump the displaced
fluid to a selected location.
It is, additionally, an object of the present invention to provide
an improved pump for downhole use which utilizes a displacing fluid
to pump well fluid to well surface and is arranged for connection
with a sucker rod string isolated from the well fluid, thereby to
obviate the aforementioned disadvantages inherent with the prior
art pumps having well fluid pumped to well surface in contact with
the sucker rod string.
It is still another object of the present invention to provide an
improved method for removing crude oil from an oil well reservoir,
such as an oil well reservoir containing unconsolidated reservoir
sands, in which the crude oil-impurity mixture in the well
reservoir is pumped to well surface without separation or
filtration.
It is also an object of the present invention to provide an
improved gas elimination system for use with downhole pumps which
operates to remove gas evolved from the well fluid from the pump
thereby to prevent gas locks.
It is another object of the present invention to provide an
improved fluid injection system for use with a downhole pump which
operates to inject controlled quantities of a diluent into a well
fluid being pumped so as to dilute and decrease the viscosity of
the well fluid.
It is yet another object of the present invention to provide an
improved method for pumping a fluid to be displaced which employs
the concept of using a displacing fluid which may be miscible with
the displaced fluid to pump the displaced fluid to a selected
location.
In accomplishing these and other objects, there is provided in
accordance with the present invention a pumping system suitable for
pumping an offensive fluid. The term "offensive fluid" as used
herein refers to any fluid the contact of which with pump parts,
particularly moving parts, is considered undesirable and
detrimental to the pump. Examples of such offensive fluids are
abrasive and erosive high viscosity fluids, corrosive acids, etc.
The fluid which is of an offensive nature may be a high viscosity
sand bearing crude oil. The pumping system provided is for a well
pumping operation and includes a sucker rod string mounted in a
fluid sealed tubing string so as to be isolated from well fluid. A
pump structure is mounted on the lower end of the tubing housing of
the sucker rod string. The pump structure includes a first chamber
housing a plunger which is connected by a downwardly extending
passage to a lower second or discharge chamber. The discharge
chamber has port means through which the crude oil-impurity mixture
forming the well fluid in the well reservoir may be pumped into the
chamber and then discharged to a point isolated from the oil
reservoir. The discharge point is connected in communication with
well surface through a production tubing string. Means are included
for supplying a controlled amount of displacing fluid of an
inoffensive lubricating nature, which preferably is kerosene, to
the plunger chamber so that a fluid interface region is formed
between the kerosene and the crude oil in the downward extending
passage. The plunger is connected to the sucker rod string and the
upper end of the sucker rod string is connected to a prime mover,
such as a pumping jack, so that the plunger may be reciprocated to
contract and expand the effective volume of the plunger chamber,
thereby the fluid interface region is displaced up and down in the
passage with the result that the displacing fluid functions at the
moving fluid interface as a piston to pump the high viscosity crude
oil up the production tubing string. Since gas is oftentimes
evolved from the well fluid, a gas trap may be associated with the
upper end of the downward extending passage and a valve operated
conduit may be connected with the gas trap to selectively conduct
trapped gas to a portion of the discharge chamber where it will be
pumped with the crude oil up the production tubing string. It has
been found however, that the replenishment of the displacing fluid
to maintain the displacing fluid -- crude oil interface inherently
operates to prevent the pumping system from gas locking.
Additionally, a fluid injection system may be associated with the
pump structure for injecting a diluent fluid into the high
viscosity crude oil so as to dilute the crude oil and thereby
reduce its viscosity. Thus, there is provided pumping system and
method of pumping wherein limited contact is made between the
offensive fluid displaced and the moving parts of the pumping
mechanism. Additionally, a pumping system is provided which is
suitable for removing crude oil by the method of pumping a crude
oil-impurity mixture without separation from a well reservoir to
well surface, thereby to significantly enhance oil producing rates
from well reservoirs characterized by being high viscosity fluent
mixtures of crude oil with impurities such as oil well reservoirs
containing unconsolidated reservoir sands.
Additional objects of the present invention reside in the specific
construction and method of operation of the exemplary well pumping
system hereinafter particularly described in the specification and
shown in the several drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of an oil well having a pumping system
according to the present invention positioned therein with the
parts of the pumping system extending downward into the well bore
illustrated in a side-by-side relationship to facilitate viewing of
the downhole portion of the pumping system;
FIG. 2 is a view taken along the line 2--2 of FIG. 1 illustrating
the downhole portion of the pumping system in its normally
clustered relationship within the well bore of FIG. 1;
FIGS. 3a and 3b are cross sectional elevation views of the downhole
portion of the well pumping system of FIG. 1 taken along line 3--3
of FIG. 2 illustrating the plunger of the pumping system on its
downstroke with FIG. 3a representing the upper half of the downhole
pumping system and FIG. 3b representing the lower half of the
downhole pumping system.
FIGS. 4a and 4b correspond, respectively, to FIGS. 3a and 3b but
illustrate the operation of the pumping system when the plunger is
on its upstroke;
FIG. 5 is a view taken along the line 5--5 of FIG. 3b;
FIG. 6 is a view taken along the line 6--6 of FIG. 3b;
FIG. 7 is a view taken along the line 7--7 of FIG. 3a; and
FIG. 8 is a side elevation view of a portion of the pumping system
of FIG. 1 which has been modified to include a diluent injection
assembly and which is partially cut away to illustrate the internal
construction of the diluent injection assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in more detail, there is shown in FIGS.
1-7 a well pumping system generally designated by the numeral 11
positioned in the bore or casing 13 of an oil well. The pumping
system 11 has vertically extending tubing strings 15 and 17
positioned within the well bore 13 to extend from the surface of
the well to the bottom region of the well whereat well fluid in the
form of high viscosity crude oil-impurity mixture 19 is located.
Such high viscosity crude oil 19 which is generally laden with sand
and silt is commonly encountered in oil drilling operations in the
Santa Maria, California region. Due to the sand and other
impurities generally found in this crude oil 19, the oil 19 is
generally of a highly offensive nature, being abrasive and erosive
and sometimes containing corrosive salt water. The tubing string 15
provides a fluid sealed housing for a string of sucker rods 21
which are connected in a conventional manner to a prime mover 23,
illustrated in FIG. 1 as a pumping jack, which is mounted at well
surface adjacent the well bore 13. It is noted that the string of
sucker rods 21 and the pumping mechanism associated with the
pumping system 11 may be driven by means other than a pumping jack,
such as, an appropriately adapted hydraulic engine, electric motor,
gas expansion engine, etc. The tubing string 17 functions as a
string of production tubing and defines means for isolating pumped
crude oil from the well reservoir and conducting the crude oil 19
to the well surface. In this manner of employing tubing strings 15
and 17, the sucker rod string 21 is isolated from the well fluid 19
so that rod fall is not restricted thereby and rod fall cycle rates
as high as ten strokes per minute may be employed for pumping well
fluid to well surface. Such rod fall rates of ten strokes per
minute may develop pumping pressures as high as 6,000-7,000 pounds
per square inch without placing undue stress on the sucker rod
string 21 which is isolated out of contact with the well fluid
19.
Mounted on the lower end of the tubing string 15 by means of a
coupler 25 is a conduit section 27 having a hollow side extension
portion 29. The conduit section 27 with its extension 29 defines a
first cavity or chamber 31. The cavity 31 is shaped to have a
cylindrical portion in line with the vertically extending string of
sucker rods 21 which defines a plunger chamber. A plunger 33 is
mounted in this plunger chamber for reciprocation up and down
therein. The plunger 33 forms a movable wall portion of the chamber
31 and functions when moved upward by the sucker rod string 21 to
decrease or contract the effective volume of the chamber 31.
Conversely, downward movement of the sucker rod string 21 moves the
plunger 33 downward to increase or expand the effective volume of
the chamber 31. The chamber 31 which is made up of the region
defining the plunger chamber and also the region enclosed by the
side extension 29 is shown in FIGS. 3a and 4a.
Connected by a coupler 35 to the lower end of the conduit section
27 is a conduit section 37 which opens on its upper end into the
conduit section 27. The conduit section 37 provides the fixed
housing in which the plunger mechanism or assembly 33 reciprocates
up and down. A traveling valve 39 is connected to the plunger
mechanism 33 to reciprocate therewith and the valve 39 which is
preferably of the ball valve type operates to control the flow of a
displacing fluid 41 in a manner hereinafter explained to the
chamber 31. The displacing fluid 41 is of an inoffensive nature and
preferably is kerosene or naptha blended with crude oil. The term
"inoffensive fluid" as used herein means a fluid which does not
attack or unduly cause wear on pump parts on contact. The
inoffensive fluid may be lubricating, as kerosene, could be
filtered crude oil, could be a solvent for dissolving paraffin
which has precipitated out of the displaced well fluid 19 onto pump
parts, or any other suitable fluid the contact of which with pump
parts is not considered undesirable. A tubular cap 43 is mounted on
the lower end of the conduit section 37 by means of a coupler 45 to
collect and provide a reservoir for the displacing fluid 41. As
shown in FIGS. 3a, 3b, 4a and 4b, the sucker rods 21 are formed to
be hollow and the displacing fluid 41 is supplied by a fluid supply
means 47 shown in FIG. 1 located at well surface adjacent the well
bore 13. The fluid supply 47 operates in a conventional manner to
supply the displacing fluid 41 at a controlled rate through the
conduit 49 to the upper end of the hollow sucker rods 21. As
indicated by the directional arrows in FIGS. 3a, 3b and 4a, 4b, the
displacing fluid 41 flows down the sucker rods 21 out an exit
portion 51 down the side of the conduit section 37 into the tubular
cap 43 whereat it is collected. The traveling valve 39 functions to
control the flow of the displacing fluid 41 upward through a
channel 53 which opens through the plunger mechanism 33 into the
chamber 31. The chamber 31 is a fluid confining chamber which
functions to hold and confine the movement of this displacing fluid
41.
Formed integral with the side extension 29 of the conduit section
27 is a preferably tubular vertically disposed conduit section 55.
The conduit section 55 communicates with the chamber 31 and defines
a downward extending passage 56 which communicates at its lower end
with a second chamber 57 formed by a conduit section 59 branching
off from the bottom portion of the conduit section 55 to extend
upward therefrom. The conduit sections 55 and 59 which are
preferably formed as one integral unit form a generally U-shaped
junction. Connected on the lower end of the conduit section 55 is a
standing valve 61 which is preferably of the ball valve type and
has an inlet port 63 connected to its lower end. The standing valve
61 in combination with the inlet port 63 provides an inlet port
means which functions as is hereinafter explained to permit the
flow of fluid, and in particular the flow of well fluid, only into
but not out from the chamber 57. The valve 61 acts as a check valve
to prevent fluid flow therethrough out from the chamber 57. It is
noted that the term "fluid," as here used, is used in a broad
generic sense to encompass all types of fluent substances including
slurries, such as 40 percent crude oil-60 percent sand slurry which
may make up an oil well reservoir. Connected to the upper end of
the conduit section 59 is a standing valve 65 mounted in a coupler
67. The coupler 67 is connected to the lower end of the tubing
string 17 and the tubing string 17 functions, as before-mentioned,
as a production tubing string for conducting pumped well fluid to
the surface of the well while isolating the well fluid pumped from
the sucker rod string and well reservoir. It is noted that the
tubing string 17 has no internal restrictions except its outer
boundary. The standing valve 65 functions as an outlet port means
for the chamber 57 through which pumped well fluid 19 is discharged
at a discharge point into the production tubing string 17 and acts
to check the flow of any fluid into the chamber 57
therethrough.
The conduit section 55 extends vertically slightly above the
extension 29 to form a gas trap chamber 69. The upper end of the
conduit section 55 has a coupler 71 with a standing valve 73,
preferably of the ball valve type, mounted therein. The valve 73
functions to bleed trapped gas from the gas trap chamber 69 into an
upper gas reservoir chamber 75 defined by a tubular cap 77
connected to the coupler 71. Connected to the upper end of the gas
reservoir chamber 75 is a conduit 81 by means of a right angled
elbow connector 79. The conduit 81 extends downward from the
connector 79 to a point adjacent the upper portion of the
structurally defined chamber 57 at which it is connected to a
standing valve 83. The valve 83 is preferably of the ball valve
type and is spring biased in a closed position. An outlet conduit
85 is connected from the ball valve assembly 83 in fluid sealing
relation through one wall of the chamber 57 to direct gas therefrom
into the upward extending portion of the conduit section 59.
Thereby, the gas is pumped through the standing valve 65 with well
fluid 19 into the string of production tubing 17. It is noted that
screen strainers 87 and 89 are mounted after and before,
respectively, the valves 73 and 83 to strain particles out of the
gas flow so as to prevent the clogging of the elbow connector 79,
the conduit 81, the valve assembly 83 or the conduit 85. Further,
it is noted that the construction of the valve 73 is designed with
its orifice relatively small so that, should gas not be evolved
from the well fluid 19 being pumped, only negligible displacing
fluid 41 will flow through the valve 73 and into the gas
elimination system or assembly provided by the gas trap 69, the
valves 73 and 83, the reservoir chamber 75, the connector 79, and
the conduits 81 and 85.
In operation of the exemplary well pumping system shown in FIGS.
1-7, initially the lubricating fluid kerosene 41 is supplied to
flood the pump chambers 31, 57 and the passage 56. Prime mover 23
is then energized and acts to reciprocate the sucker rod string 21
up and down. Thereby, the plunger 33 is driven to move up and down
and change the effective volume of the chamber 31 so that well
fluid 19 is drawn into the chamber 57 and a fluid interface is
formed in the upwardly extending channel or interface chamber
formed by the passage 56 at a point somewhere vertically between
the chambers 31 and 57. Sufficient displacing fluid 41 is supplied
to the chamber 31 to maintain the fluid interface within the
passage 56. The interface region 91 of the displacing fluid 41 and
the displaced well fluid 19 is displaced up and down with movement
of the plunger 33. The downstroke of the plunger 33 is shown in
FIGS. 3a and 3b. In this downstroke, thevalve assembly 39 is opened
by the pressure of displacing fluid 41 in the reservoir defined by
the cap 43 so that displacing fluid 41 flows upward through the
valve assembly 39 into the cavity 31. Also during the downstroke of
the plunger 33, a low pressure region is formed in the chamber 57
so that the pressure of the well fluid 19 in the bottom of well
bore 13 opens the standing valve 61 and the well fluid 19 to be
pumped which is a crude oil-impurity fluent mixture flows into the
chamber 57. This flow of fluid 19 into the chamber 57 forces the
interface region 91 upward in the passage 56 and the displacing
fluid kerosene 41 tends to flow into the expanding chamber 31, as
indicated by the directional arrows in FIGS. 3a and 3b.
Additionally, gas evolved from the oil 19 being pumped flows up the
vertical path defined by the conduit section 55 into the gas trap
69 and forces the gas-displacing fluid interface 93 in a downward
direction, as indicated by the directional arrows, during the
downstroke of the plunger 33. It is noted that the valve assembly
73 is closed by the pressure differential thereacross during the
downstroke of the plunger 33. Additionally during the plunger
downstroke, the outlet port defined by the valve assembly 65 is
closed since the displacing fluid interface 91 is moving upwards at
this time in the passage 56.
FIGS. 4a and 4b show the upstroke of the plunger 33. In the
upstroke, the plunger 33 functions to contract the effective volume
of the chamber 31 so that the displacing fluid 41 therein is forced
both upward and downward in the conduit section 55. Since at the
time the plunger 33 is moving upward the traveling valve 39 is not
being forced down into the reservoir of the displacing fluid 41
defined in the cap 43, the valve assembly 39 is closed by the
pressure differential thereacross. The downward movement of the
displacing kerosene 41 in the conduit section 55 functions to move
the interface region 91 downward in a piston-like movement in the
passage 56 so that the well fluid 19 is forced downward toward the
chamber 57. This downward movement of the displaced fluid 19 in the
chamber 57 automatically closes the inlet valve means 61 and opens
the outlet valve means 65 so that the crude oil 19 is channeled and
pumped into the production tubing string 17 upward to the surface
of the well. The upward movement of the displacing fluid 41 in the
conduit section 55 functions to increase the pressure of the gas in
the gas trap 69 so that the valve 73 opens and the evolved gas
flows into the gas reservoir 75. The gas stored in the gas
reservoir 75 is thus put under an increased pressure and flows down
the conduit 81 to open the spring-biased valve 83. The opening of
the spring-biased valve 83 bleeds off the gas in the conduit 81
down to a predetermined pressure level established by the
spring-biased valve 83. This bled off gas is discharged into the
upward extending portion of the conduit section 59 where it is
pumped with the well fluid 19 into the production tubing string 17
out of the well. It is noted that gas is normally only forced
through the gas elimination assembly during the upstroke of the
plunger 33 when the chamber 31 is being contracted to its smallest
effective volume and at which time the displacing fluid 41 is
exerting maximum pressure against gas in the gas trap 69.
Operation of the prime mover 23, thus, functions to pump oil or
well fluid 19 up the production tubing 17 in a rapid and efficient
manner since no moving parts other than the inlet and outlet ports
defined by valves 61 and 65 of the pump assembly contact the
offensive crude oil 19 being pumped. Further, the prime mover 23
may be driven at a relatively high cycle rate since the sucker rod
string 21 is siolated from contact with the well fluid 19 so that
even high viscosity fluids such as oil of the type recovered from
Santa Maria, California, can be rapidly pumped up the production
tubing 17. Also, kerosene or another light lubricating fluid is
preferably maintained within the tubing 15 around the sucker rod
string 21 which is operable to lubricate the sucker rod string 21
without restricting the rate of rod fall. This kerosene may be
supplied from the supply means 47.
Referring now to FIG. 8, a modified form of the pumping system of
FIGS. 1 to 7 is shown therein in which a downward extending fluid
injection system 95 is included. The system 95 has a conduit 97
with a spring-biased valve assembly 99 mounted on the lower end of
the conduit 97 and a connector 101 connecting the upper end of the
conduit 97 to the tubing 15. A diluent injection assembly is, thus,
provided in which a diluent fluid which may be kerosene is pumped
down the tubing string 15 through the connector 101 and the conduit
97 and is injected into the well fluid 19 at a rate controlled by
the spring-biased valve 99 through a nozzle or orifice means 103
connected to the valve 99. The flow of the diluent fluid is shown
by directional arrows in FIG. 8. Thereby, the well fluid 19 is
diluted to reduce its viscosity before being pumped into the
chamber 57 and discharged therefrom into the production tubing 17.
It is also noted that by pumping a lubricating fluid, such as
kerosene, down the tubing string 15 external of the sucker string
21 that a lubricant is automatically provided for the reciprocating
sucker string 21 which does not restrict rod fall. The diluent may
be supplied by the fluid supply means 47 or by another conventional
source.
It is noted that the exemplary pump has been tested and may be used
with or without the above-described gas elimination section
connected thereto. For example, the gas elimination assembly has
not been found necessary when using the exemplary pump to pump a
crude oil-impurity fluent mixture having an inherently low gas-oil
ratio. Further, it is noted that means may be provided so that the
pump is designed to pump both on the upstroke and the downstroke of
its plunger mechanism 33 and that while the pump structure provided
by the conduits 27, 37, 55 and 59 is illustrated connected onto the
ends of the tubing strings 15 and 17 in a downhole pumping
operation that a pump mechanism operated on the same principle
could be used in other pumping operations as well. The means for
expanding and contracting the chamber 31 could take the form of
other suitable arrangements or means other than a plunger and could
be driven by a downhole motor instead of a surface mounted prime
mover. Additionally, other equivalent type valving arrangements,
such as poppet valves, could be employed in place of the ball type
valves and the entire lower end of the pump structure could be made
the inlet means to facilitate the pumping in of extremely high
viscosity fluent mixtures into the pump structure, such as a 60
percent sand-40 percent crude oil mixture. Also, instead of using a
production tubing string to conduct the pumped well fluid 19 to
well surface, a seal could be placed in the well bore 13 to seal
off the discharge point of the pump's outlet port from the well
reservoir so that the well bore or casing 13 could be utilized as a
conduit to conduct the well fluid to well surface.
Further, it is noted that instead of pumping the displacing fluid
down the sucker rods that solid, less expensive sucker rods could
be used with other conventional means for conducting the displacing
fluid into the chamber 31. Also, the displacing fluid 41 need be
supplied to the chamber 31 only at a rate necessary to replace
displacing fluid lost during the operation of pumping the well
fluid up the production tubing 17, thereby to maintain the
displacing fluid-well fluid interface established in the passage
56. In the case of using kerosene to pump oil the displacing fluid
kerosene needs to be supplied, for example, at the rate of 10
percent of the pump's displacement. Additionally while kerosene is
illustrated as the displacing fluid, it is noted that other
suitable fluid which are of an inoffensive nature so as to not
attack or cause undue wear of the pumping mechanism could be
employed, such as water and various other suitable fluids. Filtered
oil, for example, could be used to pump a crude oil-impurity
mixture from a well reservoir. Further, it is noted that the
displacing fluid kerosene is miscible with the well fluid crude oil
and that by keeping a moving interface between the fluids that
little displacing fluid is mixed with the crude oil pumped up the
production tubing 17. While the downhole pumping system is utilized
to pump crude oil it is to be understood that other fluid-like
substances having high percentages of impurities and being
extremely abrasive and/or corrosive could also be pumped by this
pumping mechanism, such as mud. The pump could also be employed as
an acid pump by employing as the displacing fluid an inoffensive
fluid inert to the fluid being pumped to pump a high corrosive
acid, such as, anhydrous sulfuric acid.
Although I have herein shown and described my invention in what I
have conceived to be the most practical and preferred embodiment,
it is recognized that departures may be made therefrom within the
scope of my invention.
* * * * *