U.S. patent application number 14/958487 was filed with the patent office on 2016-06-09 for pumps and methods of pumping fluids into a well bore.
The applicant listed for this patent is TRICAN WELL SERVICE LTD.. Invention is credited to John (Nick) DENING, Trevor FUNK, Kurt LUCAS, Bernie LUFT, John MCNAUGHTON, Ben MIKULSKI, Barry TOPPINGS, Thomas VIS.
Application Number | 20160160848 14/958487 |
Document ID | / |
Family ID | 56087596 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160160848 |
Kind Code |
A1 |
TOPPINGS; Barry ; et
al. |
June 9, 2016 |
PUMPS AND METHODS OF PUMPING FLUIDS INTO A WELL BORE
Abstract
A pump for pumping fluid down a well bore in a rock formation
comprises: intake and discharge passages; a pumping chamber with a
plunger therein; intake and discharge valve assemblies in the
intake passage and the discharge passages. At least one valve
assembly has a valve body movable into sealing contact with the
valve seat by fluid pressure in the pumping chamber. The valve seat
may have a cylindrical outer surface for mating reception in said
intake passage, and a shoulder with a radially-projecting surface
biased against a wall for sealing. A cushioning member may be
interposed between the valve body and the valve seat. A seal may be
interposed between said valve body and said valve seat, and
configured so that between 35% and 60% of a sealing surface of said
valve seat contacts the valve body.
Inventors: |
TOPPINGS; Barry; (Calgary,
CA) ; FUNK; Trevor; (Calgary, CA) ; LUCAS;
Kurt; (Calgary, CA) ; VIS; Thomas; (Calgary,
CA) ; LUFT; Bernie; (Calgary, CA) ; MIKULSKI;
Ben; (Calgary, CA) ; MCNAUGHTON; John;
(Calgary, CA) ; DENING; John (Nick); (Calgary,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TRICAN WELL SERVICE LTD. |
Calgary |
|
CA |
|
|
Family ID: |
56087596 |
Appl. No.: |
14/958487 |
Filed: |
December 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62087018 |
Dec 3, 2014 |
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62113782 |
Feb 9, 2015 |
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62193933 |
Jul 17, 2015 |
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Current U.S.
Class: |
166/244.1 ;
166/75.11; 417/559 |
Current CPC
Class: |
F04B 7/0088 20130101;
F04B 23/02 20130101; F04B 53/16 20130101; F04B 53/1025 20130101;
E21B 41/00 20130101; F04B 47/00 20130101; F04B 53/1027 20130101;
F04B 7/0266 20130101; F04B 53/1087 20130101; F04B 53/14 20130101;
E21B 43/26 20130101 |
International
Class: |
F04B 7/00 20060101
F04B007/00; E21B 43/26 20060101 E21B043/26; F04B 47/00 20060101
F04B047/00; F04B 7/02 20060101 F04B007/02; F04B 53/14 20060101
F04B053/14; F04B 53/16 20060101 F04B053/16; F04B 23/02 20060101
F04B023/02; E21B 41/00 20060101 E21B041/00; F04B 53/10 20060101
F04B053/10 |
Claims
1. A pump for pumping fluid down a well bore in a rock formation,
comprising: an intake passage in communication with a fluid
reservoir; a discharge passage in communication with said well bore
in said rock formation; a pumping chamber with a plunger received
therein for pumping fluid from said reservoir to said well bore by
reciprocation of said plunger; intake and discharge valve
assemblies in said intake passage and said discharge passage,
respectively, for selectively sealing said intake and discharge
passages, at least one of said intake and discharge valve
assemblies comprising a valve body and a valve seat, said valve
body movable into sealing contact with said valve seat by fluid
pressure; a cushioning member interposed between said valve body
and said valve seat.
2. The pump of claim 1, wherein said valve body contacts said
cushioning member prior to contacting said valve seat, thereby
decelerating said valve body.
3. The pump of claim 1, wherein said cushioning member comprises an
elastomeric ring.
4. The pump of claim 1, wherein said cushioning member comprises a
spring.
5. The pump of claim 1, wherein said cushioning member is received
in a channel in said valve seat.
6. The pump of claim 1, wherein said cushioning member is received
in a channel in said valve body.
7. The pump of claim 4, wherein, during sealing contact of said
valve body and said valve seat, said cushioning member is
compressed such that it does not protrude from said channel.
8. The pump of claim 5, further comprising a second cushioning
member received in a channel in said valve body.
9. The pump of claim 1, wherein said valve seat has a cylindrical
outer surface for mating reception in said intake passage, and a
shoulder with a radially-projecting surface biased against a wall
of said intake passage by pressure in said pumping chamber, for
sealing therewith.
10. The pump of claim 9, further comprising a compressible seal
positioned about the perimeter of said valve body and interposed
between said valve body and said valve seat, said compressible seal
configured so that, with said valve body in sealing contact with
said valve seat, between 35% and 60% of a sealing surface of said
valve seat is in contact with said valve body.
11. A pump for pumping fluid down a well bore in a rock formation,
comprising: an intake passage in communication with a fluid
reservoir; a discharge passage in communication with said well bore
in said rock formation; a pumping chamber with a plunger received
therein for pumping fluid from said reservoir to said well bore by
reciprocation of said plunger; intake and discharge valve
assemblies in said intake passage and said discharge passage,
respectively, for selectively sealing said intake and discharge
passages, at least one of said intake and discharge valve
assemblies comprising a valve body and a valve seat; said valve
body movable by fluid pressure into sealing contact with said valve
seat; said valve seat having a cylindrical outer surface for mating
reception in said intake passage or said discharge passage, and a
shoulder with a radially-projecting surface biased against a wall
of said passage by pressure in said pumping chamber, for sealing
therewith.
12. The pump of claim 11, further comprising a resilient seal
member interposed between said radially-projecting shoulder and
said wall of said intake or discharge passage.
13. The pump of claim 12, further comprising a resilient seal
member interposed between said cylindrical outer surface of said
valve seat and a wall of said intake or discharge passage.
14. The pump of claim 12, wherein said resilient seal member is
received in a channel in said shoulder.
15. The pump of claim 11, further comprising a compressible seal
positioned about the perimeter of said valve body and interposed
between said valve body and said valve seat, said compressible seal
configured so that, with said valve body in sealing contact with
said valve seat, between 35% and 60% of a sealing surface of said
valve seat is in contact with said valve body.
16. A pump for pumping fluid down a well bore in a rock formation,
comprising: an intake passage in communication with a fluid
reservoir; a discharge passage in communication with said well bore
in said rock formation; a pumping chamber with a plunger received
therein for pumping fluid from said reservoir to said well bore by
reciprocation of said plunger; intake and discharge valve
assemblies in said intake passage and said discharge passage,
respectively, for selectively sealing said intake and discharge
passages, said intake valve assembly comprising a valve body and a
valve seat; said valve body movable by fluid pressure into sealing
contact with said valve seat; a compressible seal positioned about
the perimeter of said valve body and interposed between said valve
body and said valve seat, said compressible seal configured so
that, with said valve body in sealing contact with said valve seat,
between 35% and 60% of a sealing surface of said valve seat is in
contact with said valve body.
17. The pump of claim 16, wherein said compressible seal is
received in a channel defined in said valve body.
18. The pump of claim 17, wherein said compressible seal has a
notch for receiving a corresponding tab projecting from said valve
body to lock said compressible seal in said channel.
19. The pump of claim 16, further comprising a cushioning member
interposed between said valve body and said valve seat.
20. The pump of claim 1, wherein said pump is for hydraulic
fracturing in said reservoir.
21. The pump of claim 11, wherein said pump is for hydraulic
fracturing in said reservoir.
22. The pump of claim 16, wherein said pump is for hydraulic
fracturing in said reservoir.
23. A method of pumping fluid into a wellbore, comprising: drawing
a fluid through an intake valve of the pump of claim 1 by moving
said plunger through an intake stroke; moving said plunger through
a discharge stroke, thereby pressurizing fluid in said chamber,
closing said intake valve and opening said discharge valve and
forcing said fluid through said discharge valve into said
wellbore.
24. A method of pumping fluid into a wellbore, comprising: drawing
a fluid through an intake valve of the pump of claim 11 by moving
said plunger through an intake stroke; moving said plunger through
a discharge stroke, thereby pressurizing fluid in said chamber,
closing said intake valve and opening said discharge valve and
forcing said fluid through said discharge valve into said
wellbore.
25. A method of pumping fluid into a wellbore, comprising: drawing
a fluid through an intake valve of the pump of claim 16 by moving
said plunger through an intake stroke; moving said plunger through
a discharge stroke, thereby pressurizing fluid in said chamber,
closing said intake valve and opening said discharge valve and
forcing said fluid through said discharge valve into said wellbore.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Nos. 62/087,018, 62/113,782 and 62/193,933, the entire
contents of which are incorporated herein by reference.
FIELD
[0002] This relates to pumps for pumping pressurized fluids down
well bores, and in particular, to fluid ends of such pumps.
BACKGROUND
[0003] Many well operations require pumping of fluids at very high
pressures. For example, some wells are formed in rock formations.
Completion of such wells may involve pumping of a fluid into the
formation through a well bore at high pressure. Such pumping may
cause cracking or expansion of cracks in the formation, which may
release hydrocarbons for later extraction. Moreover, pumps may be
used to pump cement down a well bore to complete the well bore
casing, or to pump other fluids, such as acids, down the well
bore.
[0004] In such pumps, the term "fluid end" is typically used to
refer to the components that are in direct contact with fluid being
pumped. A fluid end may be driven by a power end, such as a diesel
or electric motor.
[0005] Down-hole pumping operations may require very high pumping
pressures. For example, hydraulic fracturing may require pressures
of many thousands of pounds per square inch (psi). High pumping
pressures subject fluid end components to enormous stresses. Such
stresses may cause fatigue and failure of components, requiring
costly and time-consuming maintenance.
SUMMARY
[0006] An example pump for pumping fluid down a well bore in a rock
formation comprises: an intake passage in communication with a
fluid reservoir; a discharge passage in communication with the well
bore in the rock formation; a pumping chamber with a plunger
received therein for pumping fluid from the reservoir to the well
bore by reciprocation of the plunger; intake and discharge valve
assemblies in the intake passage and the discharge passage,
respectively, for selectively sealing the intake and discharge
passages, at least one of the intake and discharge valve assemblies
comprising a valve body and a valve seat, the valve body movable
into sealing contact with the valve seat by fluid pressure; a
cushioning member interposed between the valve body and the valve
seat.
[0007] Another example pump for pumping fluid down a well bore in a
rock formation, comprises: an intake passage in communication with
a fluid reservoir; a discharge passage in communication with the
well bore in the rock formation; a pumping chamber with a plunger
received therein for pumping fluid from the reservoir to the well
bore by reciprocation of the plunger; intake and discharge valve
assemblies in the intake passage and the discharge passage,
respectively, for selectively sealing the intake and discharge
passages, at least one of the intake and discharge valve assemblies
comprising a valve body and a valve seat; the valve body movable by
fluid pressure into sealing contact with the valve seat; the valve
seat having a cylindrical outer surface for mating reception in the
intake passage, and a shoulder with a radially-projecting surface
biased against a wall of the intake passage by pressure in the
pumping chamber, for sealing therewith.
[0008] Another example pump for pumping fluid down a well bore in a
rock formation, comprises: an intake passage in communication with
a fluid reservoir; a discharge passage in communication with the
well bore in the rock formation; a pumping chamber with a plunger
received therein for pumping fluid from the reservoir to the well
bore by reciprocation of the plunger; intake and discharge valve
assemblies in the intake passage and the discharge passage,
respectively, for selectively sealing the intake and discharge
passages, at least one of the intake and discharge valve assemblies
comprising a valve body and a valve seat; the valve body movable by
fluid pressure into sealing contact with the valve seat; a
compressible seal positioned about the perimeter of the valve body
and interposed between the valve body and the valve seat, the
compressible seal configured so that, with the valve body in
sealing contact with the valve seat, between 35% and 60% of a
sealing surface of the valve seat is in contact with the valve
body.
[0009] An example method of pumping fluid into a wellbore
comprises, using a pump as disclosed herein: drawing a fluid
through an intake valve of the pump by moving said plunger through
an intake stroke; moving said plunger through a discharge stroke,
thereby pressurizing fluid in said chamber, closing said intake
valve and opening said discharge valve and forcing said fluid
through said discharge valve into said wellbore.
BRIEF DESCRIPTION OF DRAWINGS
[0010] In the drawings which illustrate, by way of example only,
embodiments of the invention:
[0011] FIG. 1 is a schematic view of a well bore in a rock
formation;
[0012] FIG. 2 is a perspective view of a pump fluid end, with a
housing thereof partially cut away;
[0013] FIG. 3 is a cross-sectional view of the pump fluid end of
FIG. 2;
[0014] FIG. 4 is a cross-sectional view of a valve assembly;
[0015] FIG. 5 is a cross-sectional view of another valve
assembly;
[0016] FIG. 6 is a cross-sectional view of another valve
assembly;
[0017] FIG. 7 is a cross-sectional view of another valve
assembly;
[0018] FIG. 8 is a cross-sectional view of another valve
assembly;
[0019] FIG. 9 is a cross-sectional view of another valve
assembly;
[0020] FIG. 10 is a cross-sectional view of another valve assembly;
and
[0021] FIG. 11 is a cross-sectional view of another valve
assembly.
DETAILED DESCRIPTION
[0022] FIG. 1 shows a schematic view of a well bore 100 drilled
through a rock formation 102. Rock formation 102 may be a shale
formation, or another suitable formation for creation of an oil
well by hydraulic fracturing.
[0023] A pump 104 may be provided for pumping a pressurized fluid
down the well bore 100. For example, as depicted, pump 104 may be
used for hydraulic fracturing. In other embodiments, pump 104 may
be used for other down-hole pumping, such as cement pumping for
completing a well bore casing or acid pumping for cleaning
components.
[0024] Down-hole pumping may require high-pressure fluids.
Accordingly pump 104 may be intended to operate at very high
pressures. For example, pump 104 may drive a fluid into well bore
100 at pressures up to many thousands of pounds per square inch
(psi), forcing the fluid to create or widen cracks 108 in formation
102. Typically, pump 104 may operate at discharge pressures of
5,000-15,000 psi.
[0025] The fluid pumped into well bore 100 may be a suitable
liquid, such as water, mixed with a proppant such as sand. The
proppant may be forced into cracks 108 along with pressurized water
and remain in the cracks after water is withdrawn, to maintain
widening of the cracks. As used herein, the combination of injected
liquid and proppant may be referred to as the fracturing fluid.
[0026] Pump 104 may comprise a fluid end 110 and a power end,
namely, motor 112. Motor 112 may drive a plunger within fluid end
110 in a reciprocating motion to pump fracturing mixture. Motor 112
may be, for example, an internal-combustion engine, such as a
diesel-fuelled engine, or an electric motor. Other suitable types
of motor will be apparent to skilled persons. Motor 112 may drive
fluid end 110 by a crankshaft 111. Motor 112 may be connected with
a geartrain, for example, to provide for operation of motor 112 and
fluid end 110 at different rotational speeds or to convert rotary
motion to linear reciprocating motion.
[0027] FIG. 2 shows fluid end 110 in greater detail. Fluid end 110
has a housing 114, which may be a cast metal block with a machined
plunger bore 116, intake passage 118 and discharge passage 120.
Housing 114 may be formed from carbon steel, stainless steel or
another material suitable to withstand high pressures.
[0028] Intake passage 118 communicates with a fracturing fluid
reservoir 117, and discharge passage communicates through an outlet
119 (FIG. 3) with a pipe 121 (FIG. 1) leading to well bore 100. A
blending pump (not shown) may be positioned upstream of intake
passage 118. The blending pump may mix liquid and proppant in the
fracturing fluid and may pressurize the fracturing fluid. As
depicted in FIG. 2, housing 114 is partially cut away for the sake
of illustration of bores 116, 118, 120 and components housed
therein.
[0029] A plunger 122 is received in plunger bore 116. Plunger 122
may be formed from steel and may be mounted to a crankshaft (not
shown) driven by motor 112 to move plunger 122 in a reciprocating
back-and-forth motion within plunger bore 116. Reciprocating motion
of plunger 122 draws fracturing fluid through intake bore 118 and
into chamber 124 and then expels fracturing fluid through discharge
passage 120 and into well bore 100. In other embodiments, plunger
122 may be replaced with a steel piston, which may be of reinforced
construction suitable to withstand high pressures experienced in
fluid end 110.
[0030] FIG. 2 depicts one plunger bore 116, one intake passage 118
and one discharge passage 120. However, fluid end 110 may have a
plurality of plunger bores 116, each with an associated intake
passage 118 and discharge passage 120. In an example, a fluid end
110 may have five sets of plunger bores 116, intake passages 118
and discharge passages 120, which may be aligned side-by-side with
one another within a common housing 114.
[0031] FIG. 3 depicts a cross-sectional view of fluid end 100. As
noted, plunger 122 is slidably received within plunger bore 116.
Plunger 122 and plunger bore 116 engage one another to form a
fluid-tight seal. Plunger 122 is slidable within plunger bore 116.
Thus, plunger 122 and plunger bore 116 form a positive-displacement
pump. Movement of plunger 122 in a first direction, indicated by
arrow I in FIG. 3 (herein referred to as an intake stroke of
plunger 122), draws fluid through intake passage 118 into a pumping
chamber 124 at the end of plunger bore 116. Movement of plunger 122
in a second direction, indicated by arrow D in FIG. 3 (herein
referred to as a discharge stroke of plunger 122), forces fluid out
of pumping chamber 124 and through an outlet 119 of discharge
passage 120 and out of fluid end 110. Plunger bore 116 and outlet
passage 120 may have stoppers 123 sealing one end thereof. Stoppers
123 may be metal (e.g. steel) and may be threaded to housing 114.
Optionally, stoppers 123 may include one or more elastomeric
sealing member (e.g. o-rings or gaskets).
[0032] An intake valve assembly 126 is received in intake passage
118 and a discharge valve assembly 128 (FIG. 2) is received in
discharge passage 120.
[0033] Each of intake valve assembly 126 and discharge valve
assembly 128 has a valve body 130, a valve seat 132 and a perimeter
seal 134.
[0034] Valve seat 132 has an inner bore 136 and a frustoconical
sealing surface 138. Valve body 130 is received in inner bore 136
and has a plurality of arms 140 extending into contact with valve
seat 132 to center valve body 130 within inner bore 136.
[0035] Perimeter seal 134 is received in an annular channel 142
extending around the underside of valve body 130. As used herein,
references to the "upper" or "top" side or surface of valve body
130 refer to the surface of valve body 130 facing away from valve
seat 132. References to the "lower", "bottom" or "under" side or
surface of valve body 130 refer to the surface facing towards valve
body 130.
[0036] Valve body 130 and perimeter seal 134 define frustoconical
sealing surfaces 142, 144, respectively, facing sealing surface 138
of valve seat 132. Sealing surface 138 and sealing surfaces 142 and
144 have complementary shapes for cooperatively forming a
fluid-tight seal.
[0037] Valve body 130 is movable away from valve seat 132
(direction .theta. in FIG. 3) to an open position, and towards
valve seat 132 (direction C in FIG. 3) to a closed position. As
depicted in FIG. 3, valve body 130 of discharge valve assembly 128
is in its open position and valve body 130 of intake valve assembly
126 is in its closed position.
[0038] Valve body 130 and valve seat 132 may, for example, be
formed from steel or another suitably strong metallic or
non-metallic material. Perimeter seal 134 may, for example, be
formed from elastomeric polyurethane or another resilient and
durable elastomer capable of withstanding abrasion and stress due
to high pressure flow.
[0039] In the open position, a passage 146 is formed between valve
seat 132 and valve body 130 to permit fluid flow. In the closed
position, sealing surfaces 142, 144 of valve body 130 and perimeter
seal 132 are urged against sealing surface 138 of valve seat
132.
[0040] Each valve body may be biased towards its closed position by
a spring such as a helical spring mounted in compression between a
top surface of valve body 130 and an internal shoulder 148 defined
in bore 118, 120.
[0041] Intake valve assembly 126 and discharge valve assembly 128
are pressure actuated. That is, high pressure in pumping chamber
124 relative to pressure outside fluid end 110 acts against the
underside of valve body 130 of discharge valve assembly 128,
causing it to open. Meanwhile, high pressure in pumping chamber 124
acts against the top surface of valve body 130 of intake valve
assembly 126, forcing it closed.
[0042] Conversely, low pressure in pumping chamber 124 relative to
the pressure outside fluid end 110 causes opening of valve body 130
of intake valve assembly 126 and closing of valve body 139 of
discharge valve assembly 128.
[0043] In order to prevent fracturing fluid from leaking past valve
assemblies 126, 128, each valve assembly may form a seal with the
wall of intake passage 118 or discharge passage 120. As will be
apparent, the seal must be robust in order to prevent leakage
despite the high pressures experienced by fluid end 110.
[0044] Accordingly, with a valve seat 132 installed in intake
passage 118 or discharge passage 120, outer wall 150 of the valve
seat 132 matingly engages an inner wall 152 of the respective
passage 118, 120. Outer wall 150 may be tapered in the closing
direction of the valve assembly. Inner wall 152 may have a
complementary taper. Thus, pressure on the top surface of valve
body 130 urges tapered outer wall 150 into tight sealing engagement
with tapered inner wall 152. Valve seat 132 may thus form a
fluid-tight seal with passage 118/120, which may tend to be
reinforced by application of pressure to close the valve
assembly.
[0045] In operation, plunger 122 is driven by motor 112 through an
alternating sequence of intake and discharge strokes. Each intake
stroke causes a drop in pressure in pumping chamber 124 and each
discharge stroke causes an increase in pressure in pumping chamber
124. During the intake stroke, pressure upstream of intake valve
assembly 126 may be greater than the pressure in pumping chamber
124, causing intake valve assembly 126 to open. Fracturing fluid is
drawn from reservoir 113 through intake passage 118 and into
pumping chamber 124. At the end of an intake stroke, plunger 122
reverses direction to begin a discharge stroke. The discharge
stroke causes an increase in pressure within pumping chamber 124.
Elevated pressure in chamber 124 acts on the bottom surface of
valve body 130 of discharge valve assembly 128, causing it to open
so that fracturing fluid is forced out of fluid end 110 through
pumping chamber 124 and discharge passage 120. At the same time,
pressure in pumping chamber 124 acts on the top surface of valve
body 130 of intake valve assembly 126, causing it to close.
[0046] As noted, the fracturing fluid may include a liquid, such as
water, and a particulate proppant, such as sand or ceramic
particles, suspended in the liquid. Accordingly, valve assemblies
126, 128 are configured to form seals even in the presence of
particulates. As best shown in FIG. 3, sealing surface 144 of
perimeter seal 134 extends downwardly past sealing surface 142 of
valve body 130. Accordingly, when valve body 130 moves to its
closed position, sealing surface 144 perimeter seal 134 contacts
sealing surface 138 of valve seat 132 prior to sealing surface 142
of valve body 130 contacting sealing surface 138.
[0047] Perimeter seal 134 and valve seat 132 may therefore form an
initial seal. When subjected to closing pressure, perimeter seal
134 may conform to any particulates present between sealing
surfaces 144, 138. That is, perimeter seal 134 may deform to form a
seal around such particulates.
[0048] After forming of an initial seal between perimeter seal 134
and valve seat 132, valve body may continue moving towards the
closed position until its sealing surface 142 abuts and forms a
seal with sealing surface 138.
[0049] In order for metal-to-metal contact between valve body 130
and valve seat 132 to occur, perimeter seal 134 may be compressed
and deformed.
[0050] In order to widen cracks 108 in rock formation 102 (FIG. 1),
plunger 122 may develop very high pressure. In an example, fluid
end 110 may be rated for pressures of up to 15,000 psi within
pumping chamber 124. At such pressure, during the discharge stroke
of plunger 122, valve body 130 and valve seat 132 of intake valve
assembly 126 may be subjected to forces of up to hundreds of
thousands of pounds in the closing direction. Such forces may be
borne by the interface between sealing surface 138 of valve seat
132 and each of sealing surface 142 of valve body 130 and sealing
surface 144 of valve body 130. Valve seat 132 may in turn transfer
forces to housing 114 of fluid end 110. In particular, the tapered
sealing interface between outer wall 150 of valve seat 132 and
inner wall 152 of intake passage 118 or discharge passage 120 may
act as a wedge. That is, the tapered interface may convert stress
exerted on valve body 130 into hoop and radial stresses around each
of the intake passage 118 and discharge passage 120. Such hoop and
radial stresses may be particularly high around intake passage 118
during the discharge stroke of plunger 122 and may frequently cause
cracking or failure of housing 114 of fluid end 110.
[0051] As will be apparent, the fracturing fluid may be
substantially incompressible. Accordingly, pressure in pumping
chamber 124 may change rapidly when plunger 122 transitions from an
intake stroke to a discharge stroke or vice-versa. Rapid increase
of pressure in pumping chamber 124 at the beginning of a discharge
stroke may cause valve body 130 of intake valve assembly 126 to
rapidly move to its closed position. Due to the high pressure
generated by plunger 122, along with the weight of the valve
assembly and closing force imparted by the bias spring,
acceleration of valve body 130 towards its closed position may be
sufficient to cause significant impact between valve body 130 and
valve seat 132. Such impact may impose further stress on one or
both of valve body 130 and valve seat 132, which may cause
deterioration or failure of either or both parts.
[0052] Accordingly, in some embodiments, valve assemblies 126, 128
may be provided with features for mitigating stress or wear.
[0053] FIG. 4 shows a cross-sectional view of an example valve
assembly 160, which can be substituted for either of valve
assemblies 126, 128. Valve assembly 160 has certain parts similar
to those of valve assemblies 126, 128, and like parts are indicated
with like reference characters. For example, valve body 130 and
perimeter seal 134 of valve assembly 160 may be substantially
identical to valve body 130 and perimeter seal 134 of valve
assemblies 126, 128.
[0054] Valve assembly 160 has a valve seat 132'. Valve seat 132'
has an inner bore 136 and a generally frustoconical sealing surface
138'. An annular channel 162 may be formed in sealing surface 138',
and a cushioning member 164 may be received in channel 162.
[0055] Cushioning member 162 is interposed between valve body 130
and valve seat 132' and is configured to decelerate valve body 130
as it approaches its closed position. Specifically, when pressure
acts on the upper surface of valve body 130, pushing valve body 130
towards valve seat 132', sealing surface 142 of valve body 130
contacts cushioning member 164 prior to contacting sealing surface
138 of valve seat 132'.
[0056] Cushioning member 164 may deform upon being contacted by
valve body 130, absorbing energy from the valve body and
decelerating the movement of the valve body. Such cushioning may
mitigate stresses due to impact of valve body 130 on valve seat
132.
[0057] As depicted, cushioning member 164 is an elastomeric ring.
Cushioning member 164 may be formed from a resilient elastomer. In
some embodiments, the material of cushioning member 164 may be
resistant to fatigue, such that cushioning member can be repeatedly
compressed to absorb shock and return to its original shape.
However, other suitable types of cushioning members may be used.
For example, cushioning member 164 could be a helical spring seated
in channel 162. Channel 162 may be configured so that cushioning
member 164 can be compressed such that it is entirely received
within channel 162. That is, when compressed, cushioning member 164
may not protrude from channel 162. When fully received within
channel 162, cushioning member 164 may not interfere with sealing
between metal sealing surface 142 of valve body, and metal sealing
surface 138 of valve seat.
[0058] As depicted in FIG. 4, cushioning member 164 is received in
a channel 162 formed in valve seat 132'. In other embodiments, a
channel 162 may be formed in the underside of valve body 130 and
cushioning member 164 received therein. For example, FIG. 5 depicts
a valve assembly 160' with a valve body 130 that has a channel 162
formed in its underside and a cushioning member 164 received
therein.
[0059] In still other embodiments, channels may be formed in both
of valve body 130 and valve seat 132 and cushioning members
received in both channels. For example, FIG. 6 depicts a valve
assembly 160'' including valve body 130' with a first channel 162a
and cushioning member 162b; and valve seat 132' with a second
channel 162b and cushioning member 164b. As depicted, cushioning
members 164a, 164b are aligned so that they abut when valve body
130' is in the closed position. However, in other embodiments,
channels 162a, 162b and cushioning members 164a, 164b may be
offset.
[0060] In some embodiments, cushioning member 164 may be a helical
spring, for example, a metal spring. FIG. 7 depicts one such
embodiment, in which valve assembly 160''' has a helical spring
cushioning member 164. Helical spring cushioning member 164 has a
lower coil 163 received in a channel 162a formed in the underside
of valve body 130', and an upper coil 165 received in a channel
162b formed in valve seat 132'. When valve body 130' is in its
closed position, channels 162a, 162b abut one another and helical
spring cushioning member 164 is compressed so that it is received
entirely within channels 162a, 162b and sealing surfaces 138, 142
can engage and seal with one another.
[0061] In other embodiments, cushioning member 164 may be formed
from other types of springs. For example, cushioning member 164 may
be a Belleville washer.
[0062] FIG. 8 shows a cross-sectional view of another example valve
assembly 170, which can be substituted for either of valve
assemblies 126, 128. Valve assembly 170 has certain parts similar
to those of valve assemblies 126, 128, and like parts are indicated
with like reference characters. For example, valve body 130 and
perimeter seal 134 of valve assembly 170 may be substantially
identical to valve body 130 and perimeter seal of valve assemblies
126, 128.
[0063] Valve assembly 170 has a valve seat 172. Valve seat 172 has
an inner bore 136 and a generally frustoconical sealing surface
138. Valve seat 172 further has an outer surface 174 and an
outwardly (e.g. radially) projecting shoulder 176 with a
radially-extending surface 177.
[0064] Unlike outer surface 150 of valve seat 132, outer surface
174 of valve seat 172 is cylindrical. That is, outer surface 174
does not taper. Valve seat 172 may be received in a bore defined in
housing 114 with a surface 178 that is likewise cylindrical. The
bore may have a shoulder with a radially-extending surface 179
opposing surface 177 of valve seat 172.
[0065] The cylindrical shape of surfaces 174, 178 may avoid the
wedge effect and consequent hoop and radial stress associated with
the tapered interface of surfaces 150, 152 (FIG. 3). When valve
body 130 is forced into its closed position by pressure acting on
the top surface of valve body 130, valve seat 172 with its
cylindrical outer surface 174 may not transfer any radial or hoop
stress to the housing in which it is received. Instead, force
exerted on valve body 130 may be borne by radially-projecting
shoulder 176. Force transferred to housing 114 may be along the
length of the valve assembly, i.e. in the open-close direction,
rather than in the radial direction. Housing 114 may be stronger in
this direction, and force transferred from shoulder 176 to housing
114 may be less likely to cause cracking or failure of housing
114.
[0066] Since surfaces 174, 178 are cylindrical, rather than
tapered, they may not engage one another as tightly as surfaces
150, 152 (FIG. 3) and therefore, may not form a metal-to-metal seal
with one another. Rather, shoulder 176 may have an annular channel
180 facing housing 114, and a seal 182 may be received therein for
sealing with the housing surface. As depicted, seal 182 may be an
elastomeric ring. However, other configurations are possible.
[0067] As will be apparent, pressure exerted on the top surface of
valve body 130 may result in valve seat 172 and thus, shoulder 176,
being urged against housing 114. This may likewise bias seal 182
against the housing. Thus, high pressure acting on valve body 130
may tend to increase the integrity of the seal formed by seal
182.
[0068] In addition, valve seat 172 may have a second annular
channel 184 formed in its circumferential face, opposing surface
178. A second seal 186 may be received within channel 184.
[0069] As noted above, when valve assemblies are subjected to
pressure in their closed positions, perimeter seal 134 may be
squeezed between the valve body and valve seat. In particular,
perimeter seal 134 may be compressed. Perimeter seal 134 may also
be subjected to shear stress. Such shear stress may tend to urge
the perimeter seal 134 out of its channel in valve body 130,
130'.
[0070] Accordingly, as shown in FIG. 3, perimeter seal 134 may have
a body 183 and an inwardly-projecting flange 186 received in
channel 142. Flange 186 extends at an angle approximately
perpendicular to sealing surface 144 of perimeter seal 134. When
valve body 130, 130' is in its sealing position, with sealing
surface 144 urged against the sealing surface of the valve seat,
flange 186 is pressed into channel 142. Pressing of flange 186 into
channel 142 may resist deformation or displacement of perimeter
seal.
[0071] As depicted in FIG. 3, valve body 130, perimeter seal 134
and annular channel 142 are configured such that sealing surface
138 partly seals with sealing surface 142 and partly seals with
sealing surface 144. Regions in which sealing surface 142 directly
contacts sealing surface 138 may be referred to as metal-elastomer
regions. Regions in which sealing surface 144 directly contacts
sealing surface 138 may be referred to as metal-metal regions. As
depicted in FIG. 3, the area of sealing surface 142 may be
approximately 0.9 times the area of sealing surface 144 and the
area of sealing surface 142 may be approximately 0.34 times the
area of sealing surface 138. Thus, metal-metal contact regions may
occupy 34% of the area of sealing surface 138 and metal-elastomer
contact regions may occupy approximately 40% of the area of sealing
surface 138.
[0072] During sealing, perimeter seal 134 may be compressed until
metal sealing surface 142 contacts sealing surface 138 of valve
seat 132. Force associated with sealing may be borne entirely or in
substantial part by the metal-metal interface between valve body
130 and valve seat 132. Perimeter seal 134 may experience stress,
such as compressive or shear stress, which may be proportional to
the amount of deformation of the metal-elastomer region. Stress on
perimeter seal 134 may cause deterioration of perimeter seal 134,
which may in turn lead to failure (e.g. leaking) of the valve
assembly. In addition, valve body 130 and valve seat 132 may
experience stress. Stress and or wearing of valve body 130, valve
seat 132 or perimeter seal 134 may be inversely related to the area
of the metal-metal interface between valve body 130 and valve seat
132 during sealing. In other words, increasing the area of
metal-metal contact may limit stress on or wearing of valve body
130, valve seat 132 or perimeter seal 134.
[0073] Thus, in some embodiments, the valve body and perimeter seal
may be configured to limit the size of the metal-elastomer contact
area between the perimeter seal and the sealing surface of the
valve seat (and correspondingly, to increase the size of the
metal-metal contact area between valve body 130 and valve seat
132).
[0074] FIG. 9 shows one such example valve assembly 190. Valve
assembly 190 has a valve body 192 and perimeter seal 194 configured
to provide large metal-metal contact area, but is otherwise
generally similar to valve assemblies 126, 128 and like components
are identified with like reference characters.
[0075] Valve body 190 has an annular channel 196 extending around
the periphery of its underside. Perimeter seal 194 has a body 198
and a flange 200 and is received in channel 196. Body 198 defines a
sealing surface 202 for sealing against sealing surface 138 of
valve seat 132. Body 198 is relatively smaller than body 183 (FIG.
3) and sealing surface 202 is likewise smaller than sealing surface
144. In the depicted example, the metal area of valve body sealing
surface 142, may be approximately 8 square inches. The area of
elastomer sealing surface 202 may be approximately 4.5 square
inches. The area of valve seat sealing surface 138 may be
approximately 16 square inches. Thus, the area of valve body
sealing surface may be approximately half of the area of valve seat
sealing surface 138. Accordingly, when the valve assembly is
sealed, about half of the area of valve seat seating surface 138
may contact valve body 130. The area of elastomer sealing surface
202 may be approximately 28% of the area of valve seat sealing
surface 138. Accordingly, when the valve assembly is sealed, about
half of the area of valve seat seating surface 138 may contact
perimeter seal 194.
[0076] In some embodiments, these sizes and ratios may vary.
Typically, the area of sealing surface 142 of valve body 130 is
between 35% and 60% of the area of sealing surface 138 of valve
seat 132. Typically, the area of metal-to-metal contact is
approximately 1.5 to 2.0 times the area of metal-to-elastomer
sealing contact.
[0077] Flange 200 may have one or more retention notches 204 formed
along its length. When perimeter seal 194 is installed to valve
body 190, retention notches 204 may receive corresponding tabs 206
extending from a wall of channel 196. The shapes of notches 204 and
tabs 206 may be such that reception of tabs 206 in notches 204
locks perimeter seal 194 in channel 196. Thus, tabs 206 and notches
204 may prevent egress of perimeter seal from channel 196 when
valve body 190 is pressed against valve seat 132.
[0078] In other embodiments, notches 204 and tabs 206 may be
omitted, in which case perimeter seal 194 may be retained in
channel 196 by urging of flange 200 into channel 196 when perimeter
seal 194 is compressed. FIG. 10 depicts such an embodiment, in
which valve body 190 has a channel 196' that is identical to
channel 196 except that it lacks tabs 206. A perimeter seal 194' is
received in channel 196 and is identical to perimeter seal 194
except that it lacks notches 204.
[0079] In some embodiments, perimeter seal 194 may be bonded in
channel 196 using an adhesive bonding agent. For example, a bonding
agent may be applied to channel 196, and molten elastomer may be
poured into channel 196. The molten elastomer may harden to form
perimeter seal 194.
[0080] Perimeter seal 194 may be sized to deform between the valve
and valve seat under pressure without allowing by-pass of fluid.
For example, perimeter seal 194 may be sufficiently large to deform
and form a seal around particulates suspended in the fluid pumped
by fluid end 110.
[0081] In some embodiments, valve assemblies may include some or
all of the features disclosed herein for mitigating stress and wear
effects. For example, FIG. 11 depicts one such valve assembly 300.
Valve assembly 300 includes a valve body 302 and a valve seat 304,
the latter received in an intake or discharge passage in housing
114 of fluid end 110.
[0082] Valve body 302 has an inner bore 306 and an outer surface
308, and a sealing surface 310. Outer surface 308 is cylindrical
and the passage of housing 114 in which it is received is likewise
cylindrical. Valve seat 304 also has a radially-projecting flange
310 which bears against a radial shoulder defined by housing 114. A
seal member 312 is disposed between flange 310 and the housing
shoulder, to define a seal that is reinforced by pressure exerted
on the top of valve body 302.
[0083] Sealing surface 308 of valve seat 304 has an annular channel
310, in which a cushioning member 312 is received to absorb energy
from closing of valve assembly 300 and thereby limit impact stress
on valve body 302 and valve seat 304. As depicted, cushioning
member 312 is an elastomeric ring. However, cushioning member 312
may be any type of cushioning member as described above.
[0084] Valve seat 304 also has an annular channel 314 extending
around the periphery of its underside, in which a perimeter seal
316 is received. Perimeter seal 316 and channel 314 are configured
similarly to perimeter seal 194 and channel 196 discussed above. In
particular, perimeter seal 316 has a body 318 and a flange 320
extending into channel 314 and is configured so that, when valve
assembly 300 is closed, the area of metal-to-metal sealing contact
between valve body 302 and valve seat 304 is approximately half of
the area of sealing surface 310. Like perimeter seal 194 and
channel 196, perimeter seal 316 and annular channel 314 have
retention notches 322 and tabs 324 to lock perimeter seal 316 in
annular channel 314.
[0085] Methods of pumping fluids down a well bore may be performed
using pumps with valve assemblies as disclosed herein. For example,
a fluid end may be provided, with one valve assembly 300 acting as
an intake valve and one valve assembly acting as a discharge valve.
Plunger 122 (FIG. 3) may be moved through an intake stroke to draw
fluid from a reservoir through an intake valve assembly 300 and
into pumping chamber 124. During the intake stroke, pressure
differential across intake valve assembly 300 causes the intake
valve assembly 300 to open and discharge valve assembly 300 to
close.
[0086] Plunger 122 may be moved through a discharge stroke, which
may pressurize fluid in pumping chamber 124. Positive pressure in
chamber 124 may cause intake valve assembly 300 to close and
discharge valve assembly 300 to open. Movement of plunger 122
likewise causes fluid to be forced through discharge valve assembly
300 and into well bore 100.
[0087] Just after the beginning of the intake stroke, pressure in
chamber 124 drops such that pressure upstream of intake valve
assembly 300 is greater than pressure downstream of intake valve
assembly 300, which causes intake valve assembly 300 to open. Just
after the beginning of the discharge stroke, pressure in chamber
124 rises, causing discharge valve assembly 300 to close. The
pressures may change quickly, resulting in rapid movement of valve
bodies 302. Valve bodies 302 may contact and compress cushioning
members 312 and flange 310 may be urged against housing 114 to seal
therewith.
[0088] The preceding discussion provides many example embodiments.
Although each embodiment represents a single combination of
inventive elements, other examples may include all possible
combinations of the disclosed elements. Thus if one embodiment
comprises elements A, B, and C, and a second embodiment comprises
elements B and D, other remaining combinations of A, B, C, or D,
may also be used.
[0089] Although the embodiments have been described in detail, it
should be understood that various changes, substitutions and
alterations can be made herein without departing from the scope as
defined by the appended claims.
[0090] Moreover, the scope of the present application is not
intended to be limited to the particular embodiments of the
process, machine, manufacture, composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present invention, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed, that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized. Accordingly, the appended claims are intended to include
within their scope such processes, machines, manufacture,
compositions of matter, means, methods, or steps
[0091] As can be understood, the examples described above and
illustrated are intended to be exemplary only. The invention is
defined by the claims.
* * * * *