Note: Descriptions are shown in the official language in which they were submitted.
Downhole Well Pum~
Technical Field
This invention relates generally to methods and means
05 for pumping oil and water from deep wells and more
particularly to the use of reciprocating pumps powered by
pressurized fluids such as gas, oil or water. Although
fluid power has long been used to power such pumps, severe
dif~iculties still exist in the pumps now available such
as sand cutting, sand fouling, vapor loc.~ing, excessive
use of energy, excessive downtime, excessive replacement
of downhole tubing and other equipment, pumping at too
fast a rate, pumping at too slow a rate, damage to
producing formations, to name a few.
lS Although the use of suc.~er rods to operate a downhole
reciprocating pump is the oldest and most wide spread
method, the well known hlgh first cost and endless
maintenance problems inherent in sucker rod systems have
almost become accepted by many operators as inevitable
which unfortunately, drives up the cost of oil and gas and
many "crooked holes" cannot be pumped at all with the use
of sucker rods. The practice of "gaslifting" liquids from
wells by injecting pressurized gas into a column of liquid
within a tubing is well known to be an inefficient system
when compressors are required to compress the gas before
injection, and it cannot be used at all in most deep wells
of today.
Therefore, particularly with regard to such wells as
offshore wells which are generally both deep and
directionally drilled, a more reliable and efficient
method and means for pumping is needed by the industr~y to
gain many millions of barrels of oil and billions of cubic
feet of gas, as the present invention provides.
Bac.~around Art
US Patents 2,362,777 and 3,123,007 disclose early
systems for hydraulically driving a reciprocating well
j L~
pump by hydrostatic and elevated pressures respectively but
neither have bearing on the present invention. Manv similar
patents e~ist, some having fluid motors for attachment to
conventional pumps or to operate a string of sucker rods which
in turn operate a conventional downhole pump.
Coberly U.S. Patent 2,952,212 issued Septem~er 13, 1960
operates by co-mingling spent power fluid with produced liquid
from the well which requires separation and purification of
the power fluid before recirculation to the downhole pump.
A later Coberly U.S. patent 3,005,414 issued October 24, 1961
employs a power fluid string and a separate string to return
spent power fluid and a production string to convey p~oduced
liquid to the surface so as to maintain the power fluid clean,
in a closed circuit. The present invention may be operated
by either method or by a reciprocation of power fluid within
one string, the production tubing being used only for produced
liquid and other conduit such as an annulus being used
to convey gas to the wellhead, as disclosed by the first
mentioned patent.
Roeder U.S. patent 4,268,227 issued May 19, 1981
provides a "free type" pump that may be removed from the well
without removal of the tubing. Copending Canadian Patent
application 414,084 filed October 25, 1982, bears the closest
physical resemblence to the apparatus of the present invention.
The above referenced application provides highly
desirable features such as the venting of gas and vapor from
the pump chamber before start of a pump stroke and filling
of the pump chamber with liquid before start of the pump
stroke but controlled from the well head. For some well
conditions, it may cause considerable difficulties to
-- 2
cr/
iZ~ i4
communicate between the pump and the power unit at the well-
head and therefore, the present invention comprises all
intelligence in the downhole pump, to thereby eliminate the
need for communication with the wellhead in order to function.
Whereas the referenced application requires a reciprocating
column of fluid to power the downhole pump, the present
invention may be operated by a reciprocating column or a
non-reciprocating column of fluld. The above application
provides a float valve to trigger a pump cycle whereas the
present invention uses a flow restrictor sensitive to a
difference in mass flow rate of a vapor as compared to a
liquid. Also, the present invention may operate without a
pressure buildup of power fluid above the normal operating
pressure to cause a return stroke of the plunger, which
therefore allows the use of lower pressure rated equipment
and even further reduction of power usage.
All of the prior art known to the inventor, takes
for granted: sand cutting of the pump and early replacement
thereof; the pumping of all sediment that enters the pump
chamber; no difference in speed between the pump and
return strokes which often requires excessive energy usage
because of a pump stroke faster than is required to pump
at the rate that the well will produce. Said prior art has
no provision within the downhole pump to sense when the
pump chamber is full of liquid and to trigger a pump or
return stroke but requires extensive communication
equipment with the surface or worse still, it must often
operate with an empty or partially empty pump chamber
which wastes energy and causes premature pump failure
because enough liquid is not present to carry heat of
friction from the pump. Said prior art has no provision to
make sliding seals resistant or immune to sand cutting and
has no provision to prevent the pumping of sediment that
enters the pump chamber which may cause e~cessive wear of
standing valves or may fill the production tubing
-- 4 --
sufficiently to stop flow to the wellhead. Therefore, it
is clear that the industry is in need of novel features
afforded by the present invention.
DISCLOS~RE OF T~E INVENTION
.=~
The present application is a division of commonly
owned Canadian Patent Application No. 434,704 filed August
16, 1983.
The present invention provides novel methods and
means within a downhole well pump to accept a pressurized
power fluid from an external source and to operate the
downhole pump such that the inclusion of sand particles or
the like in the liquid to be pumped do not adversely affect
operation or life of the pump.
All necessary intelligence is within a downhole
pump constructed and installed in accord with the present
invention such that the pump may automatically in sequence:
receive liquid, gas and vapor into the pump chamber; vent
gas and vapor from the pump chamber and up the well bore;
sense when the pump chamber is filled with liquid; admit
power fluid to the pump as required to cause a pump stroke
at a predetermined speed best suited to the particular well
conditions; stop the flow of power fluid to the pump near
the end of the pump stroke; allow return of spent power
fluid from the pump so as to allow a return stroke; use
stored energy to cause a return stroke at an optimum
predetermined speed; position all members of the pump as
required to begin a subsequent pump cycle. The present
invention may provide within the downhole pump: a lower
LCM:mls
-- 5 --
wall of the pump chamber contoured so as to direct sediment
out of the pump chamber prior to the pump chamber being
pressured so as to begin a pump stroke; sliding sealing
surfaces wetted by the produced liquid that are harder than
sand particles entrained in the produced liquid; means to
power a return stroke of the pump comprising a compressed
gas-over-oil system with provi~ion to bleed gas from the
chambers requiring the presence of oil; quick acting valve
means for controlling the flow of power fluid to and from
the pump.
In summary, therefore, the present invention
broadly provides a method for pumping liquids containing
hard particles such as sand or the like, comprising:
forcing a plunger into a pump chamber through an annular
seal ring for sealing between the plunger and the pump
chamber wall; the plunger having a surface for sealing
cooperation with the seal ring that is harder than the
sand; the seal ring having a surface for sealing
cooperation with the plunger harder than the plunger
surface, such that pressurization of the liquid is effected
without sand cutting of the sealing surfaces~
Furthermore, the invention is found in means for
pumping liquids containing hard particles such as sand or
the like, comprising: a plunger arranged for forcing into
a pump chamber through an annular seal ring for sealing
between the plunger and the pump chamber wall; the plunger
having a surface for sealing cooperation with the seal ring
that is harder than the sand; the seal ring having a
LCM:mls
1 2~9
- 5a -
surface for sealing cooperation with the plunger harder
than the plunger surface, such that pressurization of the
liquid may be effected without sand cutting of the sealing
surfaces.
Other features and advantages of my invention
will become obvious to those skilled in the art after
review of these disclosures and review of the attached
drawings.
BRIEF D~SCRIPTION OF DRA~INGS
Figure 1 depicts a downhole pump constructed in
accord with the present invention, assembled and suspended
in liquid to be pumped.
Figures 2 and 5 illustrate an arrangement for
cooperation with a reciprocating column of power fluid and
are vertical sections of Figure 1, taken 90 degrees apart.
Figures 3 and 4, when placed below Figure 2,
illustrate a vertical sectional view of Figure 1 in the
same plane as Figure 2.
LCM:mls
6'~
(6)
Figure 5 is a vertical sectional view taken along line
5-; of Figure 2.
Figurs 6 is a horizontal sectional view taken along
line 6-6 of Figure 2.
05 Figure 7 is a horizontal sectional view taken along
line 7-7 of Figure 4.
Figure 8 illustrates an alternate arrangement to that
shown in Figure 2, wherein fully automatic operations of
the pump is effected without need to reciprocate the
column of power fluid.
Figure 9 is a sectional view taken along line 9-9 of
Figure 8.
Best Mode For Carrvina Out the Invention
The assembled pump depicted generally by 20 in Figure
1 is shown suspended in the liquid to be pumped, such that
intake ports 22 are below the liquid surface 24 and such
that the upper end 26 of vent pipe 28 is above surface 24.
The pump 20 is shown suspended from tubing 30 which
conveys produced liquid to the wellhead, and from tubing
32 which conveys power fluid from the wellhead to the
pump. Surge chamber 34 may be attached at its lower end
with tubing 30 for communications therewith, as at 36. At
its upper end, head 38 is sealably attached with tubing
30, tubing 32 and vent pipe 28 for communication with each
as is later described. Other major members attached in
sequence below head 38 are tubular upper jacket 40,
tubular middle jacket 42, connector 44, tubular lower
jacket 46 and foot 48, all preferably having the same
outside diameter as the head.
Now referring to Figures 2 and 3, the upper end of
centrally disposed tube 50 may be sealably connected with
the lower end of head 38 so as to form annular pump
chamber 52 between jacket 40 and tube 50, the lower end of
head 38 deining the upper wall of chamber 52. The lower
end of jacket 40 may be bored to receive seal rings 56
alternately with spacer rings 58 for purposes to be
12'1~
.
(7)
described below. Lantern ring 60 may retain rings 56 and
58 against downward axial movement and may be aliqned such
that ports 62 formed through the wall of ring 60, allow
communication through ports 22 and 62, between chamber 52
05 and the producing formation.
The periphery of rings 58 and 60 may be formed to
receive seal rings as at 6~ suitable to maintain a seal
with the end bore of jacket 40. The end surfaces of rinqs
56 and 58 are formed flat and smooth such that an
effective seal is maintained between said surfaces when
held in contact by ring 60. Threaded tube 66 may cooperate
with mating threads formed within jacket 40 to move rings
56, 58 and 60 into intimate sealing contact with one
another, being retained against upward movement by
lS shoulder 69 formed within jacket 40. Cooperating threads
within the upper end of jacket 42 may be attached to
threaded tube 66 so as to cause jacket 42 to abut jacket
40 and firmly secure the jackets together. The lower end
of tube 50 may be sealably attached to fixed piston 68
having a maximum diameter greater than that of tube 50.
Tube 70, having a maximum diameter less than that of
piston 68 may be attached to the lower end thereof and
project downwardly through connector 44 as shown in
Figures 3 and 4 so as to allow for nut 72 to be tightened
on the lower threaded end of tube 70 against connector 44
through gland 140 and thereby preload tube 50, tube 70 and
piston 68 in tension so as to preclude buckling of tubes
50 and 70. Annular plunger shown generally at 74, may be
formed with bore 76 for slidable sealing cooperation with
seals 78 positioned around fixed piston 68 to prevent flow
around piston 68 within bore 76. Plunger 74 may be
provided with end caps 80 which have end bores as at 82 so
as to position seals 84 for slidable sealing cooperation
against the periphery of tubes 50 and 70. Bore 86 of tube
50 may convey power fluid to ports 88 through the wall of
~4~
(8)
tube 50 just above piston 68 to act within chamber 89
upwardly against the upper cap 80 and cause plunger 74 to
move upwardly. Bore 90 of tube 70 may convey return oil to
ports 92 and within chamber 93 to act downwardly against
05 the lower cap and tend to cause plunger 74 to move
downwardly.
The outer cylindrical surface 94 of plunger 74 may be
of material harder than sand or ~oreign particles that may
be entrained in the liquid to be pumped and the inner
lO- surface 96 of seaL rings 56 may be sufficiently harder
than surface 94 such that both sand cutting and gauling of
the surfaces is precluded. For instancer surface 94 may be
of chromium oxide and surface 96 may be of tungsten
carbide which will provide such hardnesses and will also
preclude corrosion of the seals.
The vertical motion of plunger 74 is limited when the
lower cap abuts connector 44 and when the upper cap abuts
head 38. Lateral movement of plunger 74 is limited by the
sliding fit between surface 94 and surfaces 96 as well as
by the contact of bores 82 with the outer surface of tubes
50 and 70. Surfaces 96 guiae the portion of the plunger
near piston 68 while tubes 50 and 70 guide the ends of
plunger 74 near head 38 or connector 44, such that surface
94 is not allowed to contact the inner wall of jackets 40
or 42, even under normal flexing of the jackets during
transport or operation of the pump.
The top of upper cap 80 is contoured so as to direct
any sediment from chamber 52 outwardly through ports 22
when plunger 74 is near the lowermost position as shown in
Figure 3.
Rings 98 may be provided within the ends of caps 80 so
as to scrape tubes 50 and 70 and thereby preclude sand
from entering bore 82 and cause excessive wear of seals
84. The outer surface of tubes 50 and 70 may be made
similar to surface g4 and the inner surface of ring 98 may
( 9 )
be made similar to surface 96 for reasons already
described.
The lowermost ring 56 positioned immediately above
member 66, prevents sediment from passing from chamber 52
05 into jacket 42 which if allowed to collect, could settle
on the upper end of connector 44 and prevent movement of
plunger 74 to its lowermost position. Ports 100 positioned
within connector 44 to drain fluid from within jacket 42
may be provided with check valves so as to prevent inflow
of fluid from the well bore upon upstroke of the plunger.
Referring now to Figure 4, jacket 46, the lower end of
connector 44 and the upper end of foot 48 define gas
chamber 102 for containing pressurized gas such as
nitrogen for use as a spring to store energy so as to
power a return stroke of the plunger. Near the lower end
of the gas chamber, oil surface 104 is maintained above
the lower end of snorkle tube 106 so as to prevent entry
of gas into tube 106. During a return stroke of the
plunger, the compressed gas in chamber 102 acts on surface
104 and forces pressurized oil up tube 106, through ports
92 to act within the lower portion of plunger 7~ against
fixed piston 68 and against lower cap 80 to thereby force
plunger 74 downwardly. Surface 104 is lowered during a
return stroke and is raised during a pump stroke as shown
at 105, to again further compress the gas within chamber
102 which in turn stores energy for the next return
stroke. 5hould gas enter tube 106 or plunger 74 through
ports 92 sized for oil, the plunger action may become less
controllable and therefore means to bleed gas is
desirable. Tube 108 may be mounted within tube 106, tube
108 having an open upper end positioned near the upper end
of tube 106 and having its lower end connected with
conventional vent valve 110 such that when valve 110 is
opened, gas acting on surface 104 forces oil up tube 106
which in turn forces gas trapped in the upper end of tube
106, into the top of tube 108 and out valve 110. To
(10 )
prevent gas from entering tube 106 during transpor. of the
pump, oil valve 112 may be provided to seal the lower end
of tube 106. Rotation of valve 112 within foot 48 may
advance valve 112 by means of cooperating sc-ew threads as
05 at 114 until seal 116 mounted around the upper
circumference of valve 112 engages the inner diameter 118
of the lower end of tube 106 and effects a seal between
them. With valve 112 closed, the pump may be laid
horizontally without gas entering tube 106. To prevent
leakage around valve 112 to atmosphere, annular seal 120
may be provided around the lower end of valve 120 for
sealing cooperation with bore 122 of foot 48. Should it be
desired to add or remove oil from chamber 102,
conventional valve 124 may be provided within foot 48.
Should it be desired to add or remove gas from chamber
102, conventional valve 126 may be provided within
connector 44. Figure 7 illustrates a configuration for
both valves 124 and i26 wherein plug 128 may be replaced
with a pressure connection to a pump or to a bleed line,
after which needle 130 is partially screwed out to allow
fluid to pass seat 132 from or to chamber 102 while no
flow is allowed to pass by seal 134 positioned around
needle 130.
Packing 13~ is retained in centrally disposed bore 138
25 within connector 44 by gland 140 so as to slidably seal
between tube 70 and connector 44 such that nut 72 may be
sufficiently tightened on tube 70 and against gland 140 so
as to preload tubes 50 and 70 against buckling and
reversal of stresses during operation of the pump.
Now referring to Figure 2, tubing 30 is sealably
connected with the upper end of head 38 and in
communication with production flow path 142 from pump
chamber 52. Located within path 142 are conventional
standing valves 144 which allow upward flow from chamber
52 into tubing 30 but allow no return. Power fluid tubing
32 is sealably connected with the upper end of head 38 and
i2'~
.
(11)
in communication with power fluid flow path 146 between
tubing 32 and chamber 89, in which power valve 148 is
positioned to control the flow. Differential piston 150
has: on its large end a first pressure area 152; on its
05 small end, a second pressure area 154; on the annular
surface between said first pressure area and said second
pressure area, a third pressure area 156; around the
cylindrical surface toward of the small end of pis.on lS0,
a fourth pressure area 158. Area 154 is exposed to the
10 power fluid pressure within tubing 32; area 158 is exposed
to the fluid pressure within path 146 which is always in
communication with tube S0; area 156 is always in
communication with open vent 158 shown in ~igure 6; area
152 is in communication with flow path 160 which is opened
15 and closed by valve 162 shown in Pigure 5 and Figure 6.
Piston lS0 is shown in its uppermost position for closure
of flow path 146 but may be moved downwardly such that
seal 164 around pressure area lS4 disengages cooperating
sealing surface on annular piston 166 to allow flow
20 between areas 154 and 158. Annular piston 166 may be
provided with a sliding seal 167 around its periphery for
cooperating with bore 168 within which it is mounted such
that a pressure below, will cause piston 166 to move
upwardly, compressing spring 170 and allow flow between
25 area lS8 and area lS4. When pressure above piston 166 is
equal or greater than the pressure below it, piston 166
will remain in its lowermost position as shown, to allow
for sealing contact with seal 164 when piston lS0 is in an
uppermost position and thereby stop flow between areas 154
30 and 158.
Differential piston 150 will remain in the closed
upward position as shown as long as the force on area lS2
exceeds the force on area 154 and conversely, it will move
to the open lower position when the force on area 152 is
3s less than the force on area 154.
lZ4~9~:i4
(12)
As best viewed in Figure 5, vent valve 162 may
comprise recess 174 formed around s~em 176 slidablv
mounted within bore 178 formed axially within valve body
180. In the lowermost position shown, r-cess 174 provides
05 for communication between flow path 172 which is in
communication with power fluid tubing 32, and flow pa~h
160 in communication with pressure are 152; vent la2 then
being closed by the upper portion of stem 176 when in the
position shown. In such position, it is clear that power
10 fluid pressure from tubing 32 acts on both ends of piston
150 which causes piston 150 to close power valve 148
because area 152 is greater than area 154, resulting in a
net upward force on piston 150.
lS Flow restrictor 184 may comprise disc 186 mounted on
the lower portion of stem 176, disc 186 being of such
diameter and configuration as required to cause a suitable
differential pressure across the disc when gas, vapor or
liquid flows around the disc within vent path 188, formed
20 axially within and through head 38. Compression coil
spring 190 may be mounted around stem 176 below body 180
such that nut 186 may be adjusted along a threaded portion
of stem 176 so as to create a desired compression load
upon spring 190 and thereby prevent upward movement of
25 stem 176 until a predetermined upward force on stem 176 is
exceeded. The predetermined force must be greater than the
differential force created across disc 184 by anticipated
flowing gas through vent path 188 but less than the force
caused by anticipated flowing liquid. Thus, as gas and
30 vapor are vented from pump chamber 52 through path 188,
stem 176 remains in the lower position but when chamber 5
becomes filled with liquid, li~uid then flows upward
through path 188 around disc 186 and creates an upward
35 force on stem 176 sufficient to overcome the preload on
spring 190 which in turn, causes stem 176 to move
upwardly. As an alternate, selected weights may be used in
place of spring 190 to provide the desired force. Plug 194
i~ 2 ~ ,3 ~ L~
(13)
may be mounted on the upper end of stem 176 for
cooperation with vent valve seat 196 formed concentrically
within body 180, such that the contact of plug 194 with
seat 196 limits the upward movernent of st~n 176 and closes
05 vent path 188. The spacing of flow paths 160, 172 and 182,
together with the length of recess 174, are such that when
stern 176 is in the lowermost position, paths 160 and 172
communicate and path 182 is closed and when stem 176 is in
the uppermost position, paths 160 and 182 communicate and
path 172 is closed. Cylindrical body 180 may have flats
cut on opposita sides as shown in Figure 6 from the
lowermost end of body 180 up to just below the level of
seat 196 so as to allow the flow of gas and vapor to flow
through seat 196 and out vent pipe 28 to the wellhead,
when stem 176 is in the lower position. Body 180 has no
flats above seat 196 so as to form a seal around body 180
against the bore of path 188.
It can now be understood that a downward acting
preload suitable for a given well condition may be
provided such that stem 176 remains in the lower position
during venting of gas and vapor from chamber 52,
maintaining vent path 188 open and maintaining pressure
area 152 in communication with power fluid tubing 32 which
in turn maintains power valve 148 closed as previously
e~cplained. It can also now be understood that when pump
chamber 52 fills with liquid, liquid begins to flow around
disc 186 to create the differential force required to
overcome the downwardly acting preload and thereby move
stem 176 to i~s uppermost position which in turn, closes
vent path 188 and flow path 172 while allowing pressure
area 152 to vent through paths 160 and 182 which in turn
causes power valve 148 to move down to the open position.
Aîter assembly and installation of the invention as
illustrated in Figure 1, operation may be described as
follows. Beginning with the configuration as depicted in
i~4~
(14)
the drawings, power fluid is maintained under pressure
within tubing 32 by a suitable fluid power source ne~r the
wellhead (not shown) as is well ~nown in the art. Because
the downhole pump is suspended below the liquid level 24
05 in the well bore, the liquid together with entrained gas
and vapor may flow into pump chamber 52 through intake
ports 22, the liquid level rising in chamber 52 while gas
and vapor escape through vent path 188, through open seat
196 and up vent pipe 28 toward the wellhead. Immediately
after chamber 52 becomes filled with liquid, liquid flows
around disc 186 which causes st~m 176 to rise and move
plug 194 against seat 196 to thereby close vent path 188
as before explained. The upward movement of stem 176 also
vents pressure area 152, allowing power valve 148 to open
and admit a flow of pressurized power fluid from tubing 32
through pressure area 158, flow path 146, tube 50, ports
88 and into chamber 89 to act against upper cap 80 in
sufficient force to move plunger 74 upwardly against the
force of liquid within chamber 52 and against the oil
pressure within chamber 93 so as to cause liquid from
chamber 52 to rise through path 142 past conventional
standing valves 144 and upwardly to the wellhead through
tubing 30. As upper cap 80 rises to contact the lower wall
of head 38, the upward movement of plunger 74 is stopped
which causes an increase of pressure within tubing 32
above the pressure necessary to raise the plunger. Upon a
conventional pressure switch mounted with tubing 32 at the
wellhead sensing such pressure increase, the pressure
within tubing 32 may be automatically vented by a motor
valve which serves to reduce the pressure within chamber
89 to hydrostatic pressure only. Gas within chamber 102
having been precharged to a pressure suitable for given
well conditions, is further compressed as plunger 74 moves
upwardly, forcing oil from chamber 93, through ports 92,
tube 70 and into the bottom of chamber 102 to cause li~uid
surface 104 to rise.
12~q3
(15)
Now, after reduction of pressur- within chamber 89 to
hydrostatic only, the oil pressure within chamber 93
driven by compressed gas within chamber 102 is suf~icient
to overcome hydrostatic pressure within chamber 89 and
05 return plunger 74 to the lowermost position which in turn
reverses the flow of the power fluid and returns gas
pressure within chamber 102 to the precharge pressure.
Power fluid returning upwardly through power valve 148
will move annular piston 166 u~?wardly against spring 170
to allow free return of power fluid regardless of the
position of piston 150, until pressures above and below
piston 166 are substantially egual, at which time, spring
170 will force piston 166 to a lowermost position and
thereby allow sealing contact with piston 150 to allow
closure of valve 148.
As plunger 74 begins to descend from the uppermost
position, a partial vacuum is created within chamber 52
which causes a downward differential pressure across plug
194 which acts together with said downwardly acting force
to move stem 176 to its lowermost position and thereby
reopen vent path 188, close vent 182 and admit power fluid
from tubing 32 through paths 172 and 160 to act against
pressure area 152 to move piston 150 upwardly to effect
closure of valve 148 and thereby return the pump to the
first configuration, ready to begin another pump cycle.
A conventional flow sensor mounted with tubing 32 at the
wellhead may be used to signal the motor valve to close
and to cause repressurization of tubing 32, after return
of the power fluid upon the return stroke of plunger 74.
As the pump stroke begins, sealing surface 94 of
plunger 74 is not in contact with any of the seal rings 56
that serve to seal chamber 52 from the well bore. Sediment
that may settle from the liquid while chamber 52 is being
filled will fall on the contoured upper surface of cap 80
to be directed towards ports 62. As plunger 74 begins to
rise, a predetermined amount of liquid is forced out
'g~
(16)
through ports 62 so as to return such sediment to the well
bore ard down below the pump. Upon surface 94 rising high
enough to contact the seal ring immediately above lantern
ring 60, such flow through ports 60 ceases and liquid
05 within chamber 52 becomes pressurized sufficiently to
force it toward the wellhead. Surface 96 of seal rings 56
may be of a slightly smaller diameter than surface 94 so
as to maintain sealing contact, rings 56 being cut a~ one
part of its periphery so as to allow minute expansion of
the ring and intimate contact of sealing surfaces 94 and
96. Because both surfaces are harder than sand, no sand
cutting will occur, causing a higher efficiency and longer
operating life of the pump.
In some installations the pump may be operating with
such a fast pump stroke that an excessive pressure buildup
tends to occur within the pump chamber before flow to the
surface within the production tubing begins, due to the
inertia of liquid within the production tubing. To prevent
such a pressure buildup and to maintain a more constant
rate of flow within the production tubing, surge chamber
34 may be provided, being suitably precharged with gas
above piston 35, to a pressure near the hydrostatic
pressure within the production tubing. Then as a pump
stroke starts and a pressure surge tends to build up
before the column of liquid begins to rise, liquid flows
into conduit 36 to act upwardly on piston 35 and further
compress the gas above it. As the column of liquid begins
to rise, the pressure surge reduces and the compressed gas
forces piston 35 back down to help continue the flow, even
after standing valves 144 have closed. Surge chamber 34
may be rotated inwardly from the position shown so as to
pass within the same size pipe that the downhole pump will
pass. Surge chamber 35 may be assembled from conventional
oilwell tubing such that any required length may be
readily assembled.
3~
(17)
For slow stroking pump installcltions, surge contr~l
may be accomplished by controlling the pump stroke s?eed
as described below, so as to star~ slow and inc~ease the
stroke speed as the column of liquid begins to rise.
o5 Wells bored into the earth have infinite combinations
of conditions such as depth, pipe diameter, pressures,
fluid characteristics, temperature, pressure ratings of
tubing joints and other eq~ipment. There~ore, it may be
desirable under some well conditions to furnish fluid
power to the downhole pump at a constant pressure and to
return spent power fluid from the pump up the production
string, tubing 30, or up a separate return string, tubing
200 as depicted in Figure 9, both methods of return well
known in the art. To operate the present invention by such
a method, alternate head 202 may be provided to replace
head 38.
Referring to Figure 8, conventional standing valves
144 are positioned to recieve produced liquid from pump
chamber 52, through flow path 122 and to convey it to
tubing 30 as described above for Figure 2. Tubing 32 is
sealably attached to the upper end of head 202 so as to
supply power fluid at a substantially constant pressure to
flow path 204 formed axially within head 202 concentric
with and below tubing 32. Now referring to Figure 9,
switching valve 206 may be positioned within bore 208
formed axially within head 202 and parallel to flow path
204 so as to protr~de into chamber 52 as shown at 210 when
in the lowermost position, and reversably movable to an
uppermost position 212 as depicted by solid lines. When
valve 206 is in the uppermost position, recess 21Dr formed
around a portion of valve stem 216 is positioned such that
spent power fluid may return from tube 50 up through
axially disposed flow path 218, through laterally disposed
flow path 220 into path 208 via recess 214, thence into
flow path 222 in communication with return tubing 200.
Should it be desired to return power fluid thrGugh
t~
(18)
production tubing 30, flow path 222 may be furnished with
a suitable chec.~ valve not shown, and connected so as to
communicate with tubing 30 instead of with tubing 200 to
thereby allow flow from path 222 into tubing 30 but no
05 return flow. While chamber 52 is filling with liquid,
valve 206 is held in the uppermost position by the
hydrostatic pressure of spent power fluid acting against
an upper enlarged end of stem 21~ as at shoulder 224, the
top end 226 of stem 216 being vented at that time. When
fluid force acting against end 226 exceeds the fluid force
acting against shoulder 224, valve 206 must move to the
lowermost position such that shoulder 224 abuts shoulder
228 and recess 214 connects flow path 230 with path 22Q
and path 222 is sealed by stem 216 above recess 214.
Valve 232 is constructed the same as valve 162
previously dèscribed except that valve 232 vents pressure
when in the lcwermost position and repressures when in the
uppermost position. When valve 232 is in the lower~ost
position as depicted in Figure 9, fluid pressure acting
against end 226 may be vented through lateral flow path
234 into valve 232 through recess 236 and thence out vent
238 to the well bore. A chec.~ valve may be installed in
vent 238 to prevent well fluid from entering the vent
path. When valve 232 is shifted to the uppermost position,
vent path 238 is closed by the valve stem and recess 236
places flow path 234 in communication with flow path 2~0
which in turn is in communication with pressurized fluid
flow path 204.
Operation of alternate head 202 may now be described,
the remainder of the pump operating as described above. As
gas and vapor are vented through valve 232, liquid rises
within pump chamber 52 until it is filled whereupon it
causes valve 232 to move to the uppermost position as
described above for valve 162, thence causing power fluid
to flow from path 204 through path 240, recess 236 and
path 234 into chamber 225 to act against end 226 of valve
( 19 )
st~m 216 to overcome hydrostatic pressure against shoulder
224 and to cause stem 216 to move to the lowermost
position such that path 222 is sealed by stem 216 and
simultaneously paths 220 and 230 are placed in
OS communication ~ia recess 214. Then pressurized power fluid
may flow from path 204 into tube 50 so as to actuate the
plunger as described above. As up~er cap 80 approaches the
top of the stroke, the cap contacts the lower end of stem
216 as at 210 and pushes the stem to the uppermost
position as at 212, whereupon, power fluid is allowed to
return from tube S0 through recess 214 and path 222 and up
the tubing to the wellhead. As the plunger starts to
descend, a vacuum is created in chamber 52 which causes
valve 232 to return to the lowermost position whic~ causes
recess 236 to vent pressure from chamber 225 through paths
234 and 238 such that hydrostatic pressure of spent power
fluid may once again act on shoulder 224 to maintain valve
206 in the uppermost position in preparation for a
subsequent pump cycle. Because the pressure area against
cap 80 is far greater than the pressure area against end
226 of stem 206, plunger 74 will easily move stem 216
upwardly and expel fluid from chamber 225 through path
234, recess 236, path 240 and back into path 204.
The return stroke speed of the plunger may be adjusted
to the fastest reasonable speed consistant with proper
operation by sizing ports 92 to restrict the flow of oil
or by regulating the return flow of spent power fluid as
by sizing ports 88 or by placing a flow restrictor at any
point along the spent power fluid return path including
placing flow restrictors at the source of pressurized
power fluid. For some well conditions it may be desired to
use only a gas chamber with no oil, for powering the
return stroke of the plunger. Any suitable conventional
flow restrictors may be utilized, depending upon the
position of installation and the flow and fluid
lZ~ i4
(20)
requirements. The pump stroke speed may be independently
regulated bv adjusting the volume output at the source of
fluid pressure mounted near the wellhead. The pump stroke
need be no faster than is necessary to pump liquid from
os the well at the rate the well is capable of producing to
thereby reduce the size of the power unit required and to
reduce the amount of power consumed to pump the well. It
may therefore be understood how to regulate the pump and
return strokes independently of one another so as to use
the minimum energy required to pump a given well.
New and timely methods, means and apparatus for
pumping liquids from deep oil wells and the like may now
be understood by study of these disclosures and review of
the attached drawings.
It is now obvious that the present invention is well
suited to attain the desired objectives and provide novel
advantages for pumping oil and water from deep wells so as
to conserve energy, to reduce maintenance requirements, to
reduce costs, to extend equipment life and to recover
hydrocarbon deposits otherwise not feasible to recover.
