U.S. patent number 3,675,714 [Application Number 05/080,340] was granted by the patent office on 1972-07-11 for retrievable density control valve.
Invention is credited to George L. Thompson.
United States Patent |
3,675,714 |
Thompson |
July 11, 1972 |
RETRIEVABLE DENSITY CONTROL VALVE
Abstract
Retrievable valve apparatus for lightening oil being gas lifted
through a tubing string. The apparatus includes a valve body having
a fishing neck which projects upwardly within the tubing string and
valve means proper carried by the body for selectively
communicating the tubing string interior with a pressurized gas
supply to inject gas into the oil upwardly past the fishing neck in
response to a predetermined pressure of oil lifted in the tubing
string above the apparatus, the valve body being provided with a
port to pass the pressurized gas into the body when the body is
selectively positioned within the string.
Inventors: |
Thompson; George L. (Fresno,
CA) |
Family
ID: |
22156763 |
Appl.
No.: |
05/080,340 |
Filed: |
October 13, 1970 |
Current U.S.
Class: |
166/319; 137/155;
166/328; 417/117; 166/322; 417/86 |
Current CPC
Class: |
E21B
43/123 (20130101); Y10T 137/2934 (20150401) |
Current International
Class: |
E21B
43/12 (20060101); F21b 033/00 () |
Field of
Search: |
;166/224 ;137/155
;417/86,108-118 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Claims
I claim:
1. Retrievable valve apparatus for lightening oil being gas lifted
through a tubing string including a valve body, a valve body
mounting sleeve coaxially within the tubing string and radially
spaced therefrom to define an annular passage, said body having a
fishing neck adapted to project upwardly within the tubing string
and valve means carried by the body for selectively communicating
the tubing string interior with a pressurized gas supply to inject
gas into oil emerging from said passage and upwardly past said
fishing neck in response to a predetermined pressure of oil lifted
in the tubing string above the apparatus, said body having a port
to pass said pressurized gas into the body when the body is
selectively positioned in the string.
2. Retrievable valve apparatus according to claim 1 including also
an actuator for the valve means comprising an axially movable
piston responsive to lifted oil pressure to move downward and to
gas supply pressure to move upward, both relative to the fishing
neck, whereby said actuator is responsive to pressure differences
between the oil and pressurized gas supply to actuate the valve
means.
3. Retrievable valve apparatus according to claim 2 including also
resilient means arranged to downwardly bias the piston.
4. The combination according to claim 3 in which said valve body
mounting means comprises a sleeve adapted to sealably receive said
apparatus in such fishing neck projecting relation that said neck
is accessible above the sleeve, and port means between said sleeve
and said body for passage of pressurized gas from without the
tubing into the valve body interior.
5. The combination according to claim 4 including also a vertically
extended bore within the valve body, a valve seat encircling said
bore, a valve stem below the bore having a portion normally
engaging the valve seat against fluid passage, a valve stem
actuator comprising a piston fixed on the stem and movable axially
within the body relative to the fishing neck, a first pressure port
for communicating lifted oil pressure around the sleeve to the
piston upper surface, and a second pressure port for communicating
gas pressure outside the tubing to the piston lower surface, said
piston being responsive to superior force on its upper surface to
unseat the stem head portion and to permit gas to flow upwardly
through the bore in the tubing.
6. The combination according to claim 5 including also compression
spring means centered on the valve stem engaging the piston in
downwardly biasing relation.
7. In apparatus for lifting oil from a well by gas under pressure
including spaced concentric tubing strings the inner string of
which is adapted to be reciprocably movable within the well, and
the outer string of which defines with said inner string a gas
pressure chamber, and means carried at the lower end of the inner
string adapted to receive oil in response to string reciprocation
to be lifted to the surface therethrough by said gas, the
improvement comprising retrievable valve apparatus to lighten oil
lifted by inner string movement, said apparatus comprising a
retrievable valve body above the oil supply level coaxially within
the inner tubing string, a valve body mounting sleeve of lesser
diameter than the inner tubing, mounting sleeve supports extending
between the inner tubing string and the mounting sleeve and
carrying the mounting sleeve for reciprocating movement with the
inner tubing string in spaced relation to the tubing to define an
annular passage circularly of the mounting sleeve within the inner
tubing string, said valve body having an upwardly projecting
fishing neck, a central fluid passing vertical bore having an
outlet adjacently below the fishing neck, first port means
communicating lifted oil pressure at the sleeve to said bore, a
second port means extending through said sleeve supports for
communicating gas pressure between the tubing strings to said bore,
valve means operatively arranged within said bore to be oppositely
responsive to lifted oil and gas pressures within the bore and
adapted to pass pressurized gas from between said strings into
lifted oil above said annular passage in said inner string, in
response to a predetermined pressure of lifted oil and during
reciprocating movement of said inner string.
8. Apparatus according to claim 7 in which said valve means
includes a needle valve stem having a pointed portion normally
engaging the valve seat against fluid passage; a valve stem
actuator comprising a piston fixed on the stem and movable axially
within the body, said first port means communicating lifted oil
pressure at the sleeve to the piston upper surface, said second
port means communicating gas pressure between the tubing strings to
the piston, said piston being responsive to superior force on its
upper surface to move downwardly to unseat the pointed stem portion
and to permit gas from between said tubing strings to flow through
the bore and upwardly into the tubing.
9. Apparatus according to claim 8 including also compression spring
means mounted on the valve stem and engaging the piston in
downwardly biasing relation.
10. Apparatus according to claim 9 in which said sleeve supports
comprise upper and lower sets of circularly spaced and radially
disposed supports at vertically spaced locations on said sleeve and
centrally within the inner tubing string, plural members of each
support set being ported and alined to provide fluid communication
therebetween.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention has to do with apparatus for lifting oil from wells
and more particularly, with density control valve apparatus and
fluid handling systems incorporating the apparatus for the
efficient removal of oil from wells such as those requiring a gas
lift assist to bring oil to the surface.
The removal of oil from wells has been accomplished by pumping
either mechanically or by gas injections into the oil to carry the
oil to the surface. In U.S. Pat. No. 2,416,359 to Thompson and
Cejka, a gas lift type of pumping operation is described in which
gas is injected into a reciprocating inner tubing string, provided
with a valve mechanism to receive and transport oil from the depths
of a well to the surface under applied gas pressure.
2. Prior Art
Gas lift pumps typically employ an inner and outer tubing string or
well casing between which gas is forced at a suitable pressure to
lift discrete quantities of oil to the surface. As the well depth
increases and bottom pressure decreases with depletion of the pool,
the weight of oil within the tubing string may be such that gas
pressure economically available is not efficient or even adequate
to lift the oil slugs to the surface.
In these cases, it has been known to provide means for lightening
the oil being lifted by injection of gas thereinto in the course of
its upward travel. Means for doing this are termed density control
valves. In the patent referred to above, a density control valve is
shown fixed to the inner tubing wall by couplings providing for the
delivery of pressurized gas into the valve for injection into the
lifted oil in response to predetermined weight conditions in the
oil.
In practice, the volume of gas injected by the density control
valve is desirably varied with changes in bottom conditions;
moreover, the valve seat may wear requiring repair. In either
instance, with previously known gas control valves, e.g. U.S. Pat.
No. 2,416,359, it has been necessary to pull the inner tubing
string to replace, repair or adjust the gas density control valve.
While pulling the string is at best a considerable inconvenience,
in the deep wells now being operated, the effort and downtime
required for so doing is likely to be economically prohibitive.
SUMMARY OF THE INVENTION
Accordingly, it is a major objective of the present invention to
provide a density control valve apparatus which is retrievable from
the tubing string for replacement, modification or repair and
replaceable in the tubing string without pulling the tubing string,
and which particularly introduces gas into the inner flowing string
in an upward direction. The valve finds particular usefulness in
connection with gas lift pump apparatus in which the inner tubing
is reciprocated in pumping oil to the surface with gas supplied to
the inner tubing through a gas lift valve.
Specifically, the invention provides a retrievable valve apparatus
for lightening oil being gas lifted through a tubing string
including above the oil supply level, a valve body having a fishing
neck adapted to project upwardly within the tubing string and valve
means carried by the body for selectively communicating the tubing
string interior with a pressurized gas supply to inject gas into
the oil upwardly past the fishing neck in response to a
predetermined pressure of oil lifted in the tubing string above the
apparatus. The valve body is provided with a port to pass the
pressurized gas thereinto when the body is selectively positioned
in the tubing string. The valve body may carry laterally projecting
means below the fishing neck for supporting the apparatus in the
tubing string and may be provided with an internal bore
communicable with the body port, e.g., plural upwardly diverging
passage means communicating the bore with the exterior portion of
the body, which portion may be annularly recessed, located
adjacently below the fishing neck. There may further be included an
actuator for the valve means comprising an axially movable piston
responsive to lifted oil pressure to move downward and to gas
supply pressure to move upward, both relative to the fishing neck,
the actuator thus being responsive to pressure differences between
the oil and pressurized gas supply to actuate the valve means.
Added downward pressure may be derived from resilient means
arranged to downwardly bias the piston.
The retrievable valve apparatus of the invention may be mounted on
a mounting means fixed within the tubing string to locate the
apparatus opposite a tubing port, the mounting means typically
comprising a sleeve adapted to sealably receive the apparatus in
such fishing neck projecting relation that the neck is accessible
above the sleeve, and ported between the valve body port and the
tubing port for passage of pressurized gas from without the tubing
into the valve body interior. The mounting sleeve may be annularly
recessed opposite the annular recess in the valve body and passage
outlet and apertured to pass fluid from the body bore into the
tubing string. The valve body port typically is in open
communication with the gas supply; and communicable with the body
port, there may be provided an axial gas passing bore. Between the
body port and the body passage, a valve seat is typically provided,
encircling the body bore. A needle valve is provided below the bore
comprising a stem pointed end having a portion which normally
engages the valve seat against fluid passage, and also having a
valve stem actuator comprising a piston fixed on the stem and
movable axially within the valve body relative to the fishing neck
thereof, a first pressure port for communicating lifted oil
pressure around the sleeve to the piston upper surface and a second
pressure port for communicating gas supply pressure outside the
tubing to the piston lower surface, said piston being responsive to
superior force on its upper surface optionally enhanced by a
compression spring centered on the valve stem and engaging the
piston in downward biasing relation to unseat the point stem
portion and to permit supply gas to flow through the bore into the
tubing.
The valve apparatus is useful in connection with apparatus for
lifting oil from a well by gas under pressure through a flow
string, e.g., the inner string of spaced concentric tubing strings
which may be adapted to be reciprocably movable within the well,
the apparatus including means carried at the lower end of the inner
string adapted to receive oil, e.g., in response to reciprocation
of the inner string to be lifted to the surface through the inner
string under pressure of gas surrounding the flow tubing string and
at a density controlled by the retrievable valve apparatus
described above located within the inner tubing for selectively
introducing gas into the flow string. In this embodiment of the
invention, pressurized gas is provided between the tubing strings.
The mounting sleeve, fixed within the inner tubing string and
opposite a port therein, serves to communicate the body port with
the gas. The valve body may be provided with a central vertical
fluid passing bore communicable with the body port and upwardly
divergent passages communicating the bore with passage outlets
above the upper end of the bore at the exterior valve body portion
adjacently below the fishing neck, with the sleeve being apertured
in a manner to form a linear continuation of said passages to
smoothly pass fluid from said bore upward into the tubing string
radially of said fishing neck. The apparatus may further include
upper and lower sets of circularly spaced supports supporting the
mounting sleeve at vertically spaced locations and centrally within
the inner tubing string, plural members of each support set being
ported and alined outwardly with inner tubing ports and alined
inwardly with sleeve and body ports to provide fluid communication
therebetween. Upper and lower annular seals may be provided between
the valve body and the sleeve, the lower seal being located between
the first and second pressure ports and the upper seal being
located between the first pressure port and said body port.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be further described as to an illustrative
embodiment thereof in connection with the attached drawings in
which:
FIG. 1 is a view in section of apparatus according to the invention
with the gas lift valve mechanism shown in the ejection cycle;
FIG. 2 is a view like FIG. 1 showing the gas lift valve mechanism
in the loading cycle;
FIG. 3a and 3b together comprise an enlarged vertical sectional
view of the density control valve with the upper portion thereof
shown in FIG. 3a and the lower portion in FIG. 3b, the valve is in
the closed position;
FIG. 4 is a view like FIG. 3b with the density control valve shown
in the normal open position;
FIG. 5 is a cross-sectional view taken on line 5--5 13 in FIG.
3b;
FIG. 6 is a cross-sectional view taken on line 6--6 in FIG. 3b;
and
FIG. 7 is a view like FIG. 1 of an alternate embodiment of the
invention apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference now to the drawings in FIGS. 1 and 2, a simple,
cased single well arrangement is depicted. Well bore 1 carries a
common form of well casing 2. The casing 2 extends downwardly into
the well bore 1 from a suitable casing landing head 3 provided at
the surface or top of the well. The casing 2 is provided opposite
the oil bearing formation stratum 4 with a perforated section or
line 5 which admits well fluid into the well casing, so that it is
available to be removed by the apparatus provided.
The casing landing head 3 is joined to the upper end of the casing
2 and such as to provide a landing for outer tubing string 7.
Concentric inner tubing string 8 which is the flow string in the
apparatus, is suspended from tubing reciprocator 9 supported above
the casing head 3 by stand 6. Reciprocator 9 is adapted to
reciprocate inner tubing string 8. While shown diagrammatically,
the reciprocator 9 may be an hydraulic piston connected to inner
tubing string 8 for alternately raising and lowering the inner
string within the outer string 7, as more particularly described in
U.S. Pat. No. 2,416,359 mentioned above, which patent is
incorporated herein by reference. Reciprocator 9 operation is at
intervals and may be controlled by a clock timed intermitter (not
shown). The reciprocation movement of the inner flow string 8 is
for the purpose of actuating slide valves 17 and 18 to control the
admission of power gas supplied to annulus 11 between inner tubing
string 8 and outer tubing string 7 through conduit 12, leading from
a compressor or other source (not shown) of gas under pressure from
the annulus to the pump chamber 13. Pump chamber 13 comprises the
lower portion of outer tubing 7 below the working barrel 10. The
pump chamber 13 is of a diameter limited by the inside diameter of
the outer casing 2 or perforated liner 5 but may be as long as
required or desired to hold a capacity to produce the well at a
desired rate determinable by the standing level of fluid in the
hole and the productivity index of the formation at 4 surrounding
the perforated liner 5.
Eductor tube 14 hangs inside the pump chamber 13 and its internal
capacity comprises part of pump chamber 13; it has its open end
near the bottom standing valve 15 and is attached at its upper end
to the inner flow string 8 to move with it.
The portion 10 of the outer tubing 7 immediately above the pump
chamber 13 forms a working barrel for upper slide valve 17 and
lower slide valve 18. The upper slide valve 17 controls the flow of
power gas to the pump chamber 13. With reference to FIG. 2, inner
flow string 8 is in the down position, the upper slide valve 17 is
sealed within working barrel 10, shutting off flow down through
annulus 11 of power gas to the pump chamber 13. The lower slide
valve 18 is in lowered position to unblock vent windows 20 in the
center portion of working barrel 10. Vertical channels 21 are
provided in the lower slide valve 18 to provide gas passageways
through the lower slide valve regardless of valve position in the
working barrel lower portion 16. Venting check valve 22 is located
in the upper reaches of the eductor tube 14 to vent the eductor
tube when the inner tubing string 8 is down, as shown in FIG. 2,
thus enabling filling of the eductor tube with well fluid. Check
valve 22 opens into the pump chamber 13 between the eductor tube 14
and the portion of outer tubing 7 defining the pump chamber 13.
When the flow string 8 is in the lowered position (FIG. 2) the
power gas is blocked, as described above, from the pump chamber 13
by the position of upper slide valve 17. In the absence of power
gas in the pump chamber 13, the venting check valve 22 is free to
open. The vent windows 20 unblocked by virtue of the lowered
relative position of lower slide valve 18 are open to the annulus
23 defined outwardly by the casing 2 which now contains oil and gas
at formation pressure. Pump chamber 13 accordingly fills by
submergence in the accumulated fluid in the casing through bottom
standing valve 15 to commence the loading cycle.
The loading cycle is timed by the mentioned clock intermitter or
other device so that the pump chamber 13 will just fill before the
reciprocator 9 lifts the flow string tubing 8. Upward movement of
the flow string tubing 8 causes lower slide valve 18 carried
thereby to first close vent windows 20 to annulus 23. Sequentially
upper slide valve 17 is moved upwardly and out of working barrel 10
which permits flow of power gas downwardly through annulus 11 and
lower slide valve channels 21 into the top of pump chamber 13. The
gas pressure within the outer portion of pump chamber 13 closes
venting check valve 22 as the formation pressure thereon is
overcome. Similarly, lower standing valve 15 closes by virtue of
pump chamber 13 becoming full or from pressure therewithin. The
fluid within pump chamber 13 is thus forced upwardly in the eductor
tube 14 past upper standing valve 24 and into the lower end of flow
string 8 (see arrows, FIG. 1), whereupon the lifting apparatus,
i.e., reciprocator 9, may be recycled to displace another slug or
pumping chamber-filling quantity of well fluid into the lower
reaches of the flow string tubing 8, by lowering this tubing string
to vent the pump chamber 13 as above described, to permit filling
with well fluid which has again accumulated through the casing
perforated section 5.
This pumping cycle may be repeated at any desired rate, e.g., to
have several slugs of production fluid in transit to the surface at
any one time, enabling characteristically high production rates
with the apparatus described.
The well fluid lifting apparatus thus far described is
conventional. In the use thereof there may be employed a density
control valve 25 located in the lower reaches 26 of the flow string
tubing 8 for the purpose of allowing a determined amount of gas to
enter the flow string interior 27 laterally from annulus 11 between
tubing strings 7, 8, so as to lighten too heavy weights of
production fluid in the flow string 8 and in response to a
predetermined differential of between the flow string 8 interior
pressure at the valve 25 and the power gas pressure in the annulus
11.
The density control valve 25 of the present invention is a
departure from valves heretofore employed for like purposes of
lightening fluid production. Particularly this valve discharges its
gas in an upward direction assisting the upward travel of the fluid
being pumped upwardly from pump chamber below. Also the present
density control valve is a retrievable apparatus, locatable from a
distance, i.e., above ground, within a flow string and removable
therefrom by wire line without pulling the string from the
well.
With reference to FIGS. 3a and 3b, which depict a single
retrievable valve apparatus according to the invention, it will be
seen that the density control valve apparatus of the invention
includes a valve body 28 having an upwardly, freely projecting
fishing neck 29 of slightly lesser diameter than the valve body and
carrying suitable annular ribs 30 adapted for engagement with a
wire carried retrieval tool (not shown). A laterally projecting
latch 31 such as a Type R latch is secured to the fishing neck 29
for the purpose of supporting the valve body 28 in place. Below the
fishing neck 29, the valve body 28 comprises plural sections in pin
and box threaded connection including a two part upper annular
section 32 defining an axial vertically extended bore 33 and plural
upwardly divergent passages 34 communicating the bore with exterior
annular portion 35 of the upper valve body section adjacently below
the fishing neck. The valve body section exterior portion 35 is
annularly recessed as shown at the level of passage outlets 36
above the upper terminus 37 of bore 33. Upper recess edge 38 is
beveled to provide a smooth continuation of the flow path through
passages 34, outwardly from the valve body 28 and upwardly through
ports 81 into flowing annulus 27 carrying production from pump
chamber 13 below.
A valve seat 39 is provided in the lower part of the upper annular
section 32 of the valve body 28 at the lower terminus 40 of the
bore. Valve seat 39 is provided with a restricted opening 41
selected to provide the desired control over gas passage through
the valve opening when wide open and is replaceable by
disconnecting the lower part of annular section 32 and the coupling
42 to vary the restriction on gas flow into the bore 33.
COupling 42 comprises a body 43 having a central annular recess 44
and radial ports 45 adapted for communication with power gas in
annulus 11 as will be described below leading from the recess into
an axial bore 46 which is suitably of the same diameter as bore 33
in upper and lower parts of upper annular section 32 spaced from
bore 46 across the valve seat 39. Bore 46 in the coupling is
adapted to receive valve stem 47 from below carrying at its upper
end above labyrinth sealing rings 48, a pointed terminal 49
configured as a needle valve to seat fluid tightly on seat 39
around valve opening 41.
Below the coupling 42 to receive and guide valve stem 47 there is
provided guide block section 50 of the valve body. Guide block
section 50 comprises an elongated cylinder having formed
therewithin a downwardly stepped axial bore 51 in which valve stem
47 reciprocates to operate the stem pointed portion 49 with respect
to the valve seat 39. Valve stem 47 carries a piston 52 having
labyrinth sealing rings 53 and movable within the lower, larger
diameter portion 54 of the stepped bore 51 to actuate the needle
valve. Radial ports 55 are provided through section 50 at annular
recess 56 above the travel of the piston 52 to communicate upper
bore portion 57 with flow string tubing interior 27 whereby
pressure of lifted oil about the valve body 28 is transmitted to
the upper surface 58 of the piston. A compression spring 59 is
provided in the upper bore portion 57 centered on the valve stem 47
and engaged between the bore step 60 and the piston upper surface
58 to bias the piston 52 downwardly to thus resiliently assist
depression of the valve stem 47 and opening of the valve at 41. The
power of spring 59 is selected to provide a desired preload on the
piston 52.
Terminal 61 below the piston 52 terminates lower bore portion 54
and through radial ports 62 in annular recess 63 and axial passage
64 is adapted to communicate the bore below the piston with annulus
11 between the outer and inner tubing string 7 and 8 which is power
gas containing so that annulus 11 gas pressure is sensed by the
piston 52 at its lower surface 65 in a manner biasing the piston
and stem upward.
The valve body 28 is retrievably supported in cylindrical sleeve
66. Latch 31 engaging internal annular recess 67 in the sleeve
locks valve 28 into place and prevents it from being blown upward
out of position. The sleeve 66 is fixed in the tubing section 8a
which is pin and box connected into the flow string tubing 8.
Support ribs 68 center the sleeve 66 and serve to guide the valve
body 28 into the sleeve. Plug 69 threaded into the lower end of
sleeve 66 also supports the valve body 28 and in appropriately
registered and selected alinement of its ports 45, 55 and 62,
respectively with upper sleeve apertures 70 intermediate sleeve
apertures 71 and lower sleeve apertures 72.
Sleeve apertures 70 and 72 in turn are in open communication with
upper rib and tubing apertures 73, 74 and lower rib support and
tubing apertures 75, 76. Intermediate sleeve apertures 71 are open
to fluid within tubing string interior 27. See FIG. 6. Thus piston
52 is simultaneously subjected to a pilot pressure on its upper
surface 58 from lifted oil through oil from tubing interior 27
entering aperture 71, the upper pressure port 55 and upper bore
portion 57, and pilot pressure on its lower surface 65 from the
pressurized gas supply in annulus 11 entering through tubing
aperture 75, rib aperture 76. Sleeve aperture 72, the lower
pressure port 62, bore 64 and lower piston bore 54. Spring 59
biases the piston downwardly to establish the actuating force
differential across the piston required to effect operation of the
valve, e.g., 200 pounds.
Middle body and lower body sets of annular seals 77, 78 and 79, 80
are provided between the valve body 28 and the sleeve 66, with
lower seals 79, 80 being located between the upper pressure port 55
and the lower pressure port 62 to fluid tightly seal the body and
sleeve between these ports and with middle seals 77, 78 being
located between the upper pressure port 55 and the body port 45 to
fluid tightly seal the body and sleeve between these ports.
Annular seals 82 and 83 seal off power gas at port 45 from escaping
upwardly between valve body 28 and sleeve 66 and comingling with
controlled gas at 81.
In operation of the invention apparatus and with particular
reference to FIGS. 3b and 4, power gas is delivered through annulus
11 to cause fluid to be lifted into inner tubing string 8 as
described. Several slugs of fluid may be passing through tubing
string 8 at one time. The piston 52 is arranged to oppositely sense
lifted fluid pressure and gas pressure as described. When these
pressures are at a predetermined differential, the piston 52 moves
down and opens valve opening 41. See FIG. 4. Power gas which has
entered the valve body 28 through body port 45 in open
communication with annulus 11 through rib support aperture 74 and
tubing aperture 73 (see FIG. 5) moves into bore 33 and is jetted
upwardly and outwardly by passages 34 through outlets 35 and sleeve
openings 81 into tubing interior 27 up between support ribs 68 to
rush past fishing neck 29 and into the fluid within the tubing to
lower the density thereof or to lighten the same. Upon lowering the
density of the fluid, the piston 52 moves upwardly and closes the
valve opening 41 until a too heavy fluid weight condition again
occurs. Production passes upwardly in tubing 8 through reciprocator
9 and out through manifold 84.
The upwardly discharging, retrievable valve of the invention in the
described apparatus is believed superior to all other flow valve
systems now known. The valve is further useful in conjunction with
a conventional well gas lifting apparatus shown highly simplified
in FIG. 7 wherein like parts to FIGS. 1-6 are shown with like
numerals with the addition of 100 e.g., casing 102. Power gas from
line 112 is run down the annulus 111 to packer 190 so as to not
exert pressure on the producing zone inward of stratum 104 in
casing 105. Density control valve 125 operating on the differential
between fluid in flow string interior 127 and annulus 111 between
casing 102 and tubing string 108 is admitting its gas in an
upwardly jetting direction and serves to lighten the lifted fluid
as described above with the lifting gradient within the tubing
controllable by the power gas pressure in the annulus 111.
Alternatively packer 190 may be omitted and no power gas used where
the formation gas pressure is sufficient to lift the well with the
help of the upwardly directed valve 125, if the formation pressure
in stratum 104 is sufficient.
* * * * *