Note: Descriptions are shown in the official language in which they were submitted.
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FRACTURING HEAD WITH REPLACEABLE INSERTS FOR
IMPROVED WEAR RESISTANCE AND METHOD OF
REFURBISHING SAME
TECHNICAL FIELD
The present invention relates in general to the
fracturing of subterranean hydrocarbon formations and, in
particular, to a wear-resistant fracturing head used to
pump high pressure fluids and abrasive proppants into a
well requiring stimulatian.
BACKGROUND OF THE INVENTION
Subterranean hydrocarbon formations are routinely
stimulated to enhance their geological permeability. A well
known technique for stimulating a hydrocarbon formation is
to fracture the formation by pumping into the well highly
pressurized fluids containing suspended proppants, such as
sand, resin-coated sand, sintered bauxite or other such
abrasive particles. A fracturing fluid containing
proppants is also known as a "slurry."
As is well known in the art, a fracturing head (or
"fray head") has ports to which high pressure conduits
known as "fray lines" are connected. The fray lines
conduct the highly pressurized slurry from high pressure
pumps to the fracturing head. The fracturing head is
typically secured to a wellhead valve. The fracturing head
includes a main body with a central bore for conveying the
slurry downwardly into the well. Due to the high fluid
pressures, high transfer rates and the abrasive properties
of the proppants in the slurry, components of the
fracturing head that are exposed to the pressurized slurry
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erode or "wash", as such erosion is referred to by those
familiar with well fracturing processes.
As is well known in the art, fracturing heads are
expensive to manufacture because they are made from
hardened tool steel (AISI 4140, for example). Attempts have
therefore been made to provide hardened, wear-resistant
inserts that can be replaced in order to extend the service
life of a fracturing head. For example, published Canadian
Patent Application No. 2,430,784 to McLeod et al.,
describes a fracturing head with a replaceable abrasion-
resistant wear sleeve secured in the main bore in the body
of the fracturing head. The fracturing head defines a
generally Y-shaped flow path. At least two streams of
fracturing slurry are pumped through respective side ports
angled at approximately 45 degrees to the main bore. The
two streams of slurry mix turbulently at a confluence of
the side ports. The slurry then flows downstream through
the main bore and into the well. The wear sleeve is
positioned so that the respective streams of slurry are
directed at the wear sleeve rather than at the body of the
fracturing head which, being of a softer steel that that of
the wear sleeve, is more prone to erosion. However, due to
the location of the wear sleeve, the turbulent slurry
impinges a top edge of the wear sleeve, which tapers to a
feathered edge. The feathered edge of the wear sleeve thus
has a tendency to erode. As the feathered top edge erodes,
pressurized slurry flows between thE: wear sleeve and the
body of the fracturing head, eroding the body of the
fracturing head, causing damage.
Consequently, there exists a need for a fracturing
head with improved wear resistance.
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SUNINIARY OF THE INVENTION'
It is therefore an object of the invention to
provide a fracturing head with improved wear resistance.
In accordance with a first aspect of the invention,
a fracturing head includes a main body having a side port
for connection to a high pressure line that conducts high
pressure fracturing fluids from a high pressure pump, the
main body including a main bore in fluid communication with
the side port for conveying the fracturing fluids through
the fracturing head. The fracturing head further includes
a replaceable wear-resistant insert secured within the main
bore and an annular sealing element disposed around a top
end of the insert for inhibiting the fracturing fluids from
penetrating an annular gap between the insert and the main
body.
In one embodiment, the fracturing head includes a
plurality of annular sealing elements disposed between the
insert and the main body for inhibiting the fracturing
fluids from penetrating the annular gap between the insert
and the main body.
In accordance with a second aspect of the
invention, a fracturing head includes a T-shaped main body
having a main bore that extends from a port in a top end of
the main body through a bottom end of the main body; a pair
of side ports having side port bores that communicate with
the main bore; at least one replaceable wear resistant
insert that is received the main bare; and at least one
replaceable wear-resistant insert received in each of the
side ports.
In one embodiment, the at least one replaceable
wear-resistant insert that is received in the main bore
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includes: a first replaceable wear-resistant insert
received in the port in the top end of the main body; a
second replaceable wear-resistant insert received in the
main body beneath the first insert, the second insert
including opposed circular seats for respectively receiving
inner ends of the inserts received in the respective side
ports; and a third replaceable wear-resistant insert that
is received in a retainer flange connected to a bottom end
of the main body.
In accordance with a third aspect of the invention,
a fracturing head includes a main body having at least two
angled side ports for connection to respective high
pressure lines that conduct high pressure fracturing fluids
from high pressure pumps, the main body including a main
bore in fluid communication with the angled side ports for
conveying the fracturing fluids through the fracturing
head. The fracturing head also includes a replaceable
wear-resistant insert secured in the main bore downstream
of the side ports, the insert having an impingement surface
against which substantially all of a jet of pressurized
fracturing fluids directly impinges when pressurized
fracturing fluids are pumped through one or more of the
angled side ports, the impingement surface being between
top and bottom ends of the wear resistant insert. The
fracturing head further includes at least one annular
sealing element disposed between a top end of the wear
resistant insert and the main body for inhibiting the
fracturing fluids from penetrating between the wear
resistant insert and the main body.
In accordance with a fourth aspect of the
invention, a method of refurbishing a fracturing head
includes the steps of disassembling the fracturing head;
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removing a worn replaceable insert from a bore of a main
body of the fracturing head; removing, inspecting and
replacing any worn annular sealing elements associated with
the replaceable insert; inserting a new replaceable insert
in the bore of the main body; and reassembling the
fracturing head.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present
invention will become apparent from the following detailed
description, taken in combination with the appended
drawings, in which:
FIG. 1 is a front elevation view of a T-shaped
fracturing head in accordance with an embodiment of the
invention;
FIG. 2 is an exploded view of the fracturing head
shown in FIG. l;
FIG. 3 is a cross-sectional view of another T-
shaped fracturing head in accordance with another
embodiment of the invention; and
FIG. 4 is a cross-sectTOnal view of a Y-shaped
fracturing head in accordance with yet a further embodiment
of the invention.
It will be noted that throughout the appended
drawings, like features are identified by like reference
numerals.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In general, and as will be explained in detail
below, a fracturing head in accordance with the invention
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includes one or more replaceable wear-resistant inserts and
annular sealing elements for inhibiting fracturing fluids
from circulating between the inserts and a main body of the
fracturing head. Worn inserts and degraded sealing
elements are easily replaced to refurbish the fracturing
head without replacing or rebuilding the main body. Service
life of the main body is therefore significantly prolonged.
As will be described below, in one embodiment, an entire
flow path through the main body is lined with wear-
resistant replaceable inserts to further prolong the
service life of the main body.
As shown in FIGS. 1 and 2, a fracturing head 10 in
accordance with an embodiment of the invention includes a
T-shaped main body 12. The main body 12 Includes a top
port 14 as well as a pair of opposed side ports 16 to which
high-pressure lines (not shown) can be connected and
through which pressurized fracturing fluids can then be
pumped. As is known in the art, the fracturing fluids
include a slurry of treatment fluids and abrasive proppants
which the fracturing head 10 conducts down the well for
fracturing subterranean hydrocarbon formations. The main
body 12 can be secured to the top of a retainer flange 18
which in turn can be secured to a wellhead assembly (not
shown) .
As shown in FIG. 2, the fracturing head 10 further
includes one or more of a plurality of replaceable wear-
resistant inserts and annular sealing elements collectively
designated by reference numeral 20. The wear-resistant
inserts (or "sleeves") and associated annular sealing
elements can be secured within one or more bores in the
fracturing head 10 in order to provide a wear-resistant
flow-path lining that inhibits erosion of the main body 12
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and thus prolongs the service life of the fracturing
head l0. The various inserts will now be described
individually.
As shown in FIG. 2, a main insert 22 can be
inserted into a main bore in the main body 12. The main
insert 22 is a thick-walled sleeve having circular
apertures at top and bottom ends. The main insert 22
further includes, in the cylindrical side wall, two opposed
circular apertures each surrounded by an annular lip. The
main insert can therefore receive respective side port
inserts 26 as well as respective side gaskets 33. The side
port inserts 26 are designed to be inserted into respective
bores in the opposed side ports 16. Similarly, a top port
insert 24 can be inserted into a bore in the top port 14.
Furthermore, a retainer flange insert 28 can be inserted
into a bore in the retainer flange 18.
An upper annular sealing element 30 and a lower
annular sealing element 32 provide fluid-tight seals above
and below the main insert 22. The upper annular sealing
element 30 is disposed around a top end of the main
insert 22 to inhibit the fracturing fluids from penetrating
an annular gap between the main insert 22 and the main
body 12. The lower annular sealing element 32 is disposed
directly beneath the main insert 22, i.e., where the main
insert 22 abuts both the retainer flange 18 and a retainer
flange insert 28. A pair of side gaskets 33 provide fluid-
tight seals between the side port inserts and the main
insert 22.
As will be readily appreciated by those of ordinary
skill in the art, the fracturing head 10 may include only a
single insert and a respective sealing element or it may
include any combination of replaceable inserts and annular
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sealing elements. The inserts and annular sealing elements
may be disposed contiguously to provide a protective lining
over the entire flow path or merely over only a portion of
the flow path.
FIG. 3 is a cross-sectional view of another
T-shaped fracturing head 10 in accordance with another
embodiment of the invention. The fracturing head 10 shown
in FIG. 3 includes a T-shaped main body 12 having a main.
bore 13. The main body 12 also includes a top port 14
having a top bore 15 as well as a pair of opposed side
ports 16 having respective side bores 17, all of which are
in fluid communication with the main. bore 13. A retainer
flange 18 is secured to the bottom of the main body 12.
The retainer flange 18 includes a retainer flange bore 19
which is also in fluid communication with the main bore.
The main bore 13, top bore 15, side bores 17 and retainer
flange bore 19 together define a flow path through the
fracturing head 10.
The side ports 16 and the top port 14 are threaded
for the connection of high-pressure lines (not shown) for.
conducting high-pressure fracturing fluids from a high-
pressure pump (not shown) into the well. It is common
practice to connect high-pressure lines to two of the three
ports for inflow of pressurized fracturing fluids into the
fracturing head while the third port is closed with a valve
and reserved for pressure alleviation in the event of
"screenout". These highly pressurized fracturing fluids
mix turbulently at the confluence of the side bores and top
bore and then flow downwardly into the well through the
main bore 13 and retainer flange bore 19.
As shown in FIG. 3, a main (replaceable wear-
resistant) insert 22 is secured within the main bore 13 in
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the main body 12. In this embodiment, the main insert 22
includes a nozzle with an internal taper used to direct a
flow of fluid from the side ports (and/or top port) through
a bottom of the fracturing head. Upper and lower main
annular sealing elements 30, 32 are disposed along the
upper and lower surfaces of the main insert 22 in order to
inhibit penetration of abrasive fracturing fluids into an
annular gap between the main insert 22 and the main
body 12. Consequently, the susceptibility of the main body
to erosion is diminished, thus prolonging the service life
of the fracturing head.
In the embodiment illustrated in FIG. 3, the
fracturing head also includes a second main bore insert 23
secured within the main bore 13 upstream of the first main
bore insert 22. The second main bore insert and the first
main bore insert 22 are separated by the upper annular
sealing element 30.
As shown in FIG. 3, the side bores 17 of each side
port 16 are also protectively lined with respective side
port inserts 26. Similarly, the top bore 15 of the top
port 14 includes first and second top port inserts 24, 25
separated by a top port annular sealing element 34. A pair
of side port annular sealing elements 36 are disposed
circumferentially around the side bores 17 at the abutment
of the side port inserts 26 and the second top port
insert 25 and the second main bore insert 23.
As shown in FIG. 3, the retainer flange 18 includes
a retainer flange insert 28 within the retainer flange
bore 19. The top of the retainer flange insert abuts the
lower main annular sealing element 32.
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As shown in FIG. 3, a pair of annular grooves 38
are machined into the bottom of the main body 12. Each of
the annular grooves 38 receives an O-ring for providing a
fluid-tight seal between the bottom of the main body 12 and
the retainer flange 18. Further annular grooves 40 are
machined into both the bottom of the main body 12 and the
top of the retainer flange 18 for accommodating a metal
ring gasket as described in applicant's co-pending Canadian
Patent Application Serial Number 2,445,468 filed
October 17, 2003 and entitled METAL RING GASKET FOR A
THREADED UNION.
The retainer flange 18 is secured to the bottom of
the main body 12 of the fracturing head 10 using threaded
fasteners (which are not shown). The retainer flange 18
includes an upper flange having a plurality of
equidistantly spaced bores 42. The bores 42 in the upper
flange align with corresponding tapped bores 44 in the
bottom of the main body 12.
In one embodiment, the annular sealing elements are
ring gaskets made of either a hydrocarbon rubber (such as
Viton~ Nordel~ available from Dow Chemical) or a
polyurethane.
In one embodiment, the main body 12 and the
retainer flange 18 are machined from AISI 4140 heat-treated
steel whereas the inserts are machined from a harder steel
such as AISI 4340 steel having a Rockwell C Hardness of
48-56.
FIG. 4 is a cross-sectional view of a Y-shaped
fracturing head in accordance with yet a further embodiment
of the invention. In this embodiment, the fracturing
head 10 includes two angled side ports 16 each having a
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side bore 17 in fluid communication with a main bore 13.
In use, high-pressure lines are connected to the angled
side ports 16 and/or to the top port 14 in the manner
described above. High-pressure fracturing fluids are thus
conducted at high velocity down the side bores and/or top
bore. These fracturing fluids mix turbulently at the
confluence of the maim bore, top bore and side bores and
the fluids flow downwardly into the well through the main
bore 13 and the retainer flange bore 19.
As shown in FIG. 4, a main replaceable wear-
resistant insert 22 is secured in the main bore 13
downstream of the side ports 16. The main insert 22 has an
impingement surface 50 against which substantially all of a
jet of pressurized fracturing fluids directly impinges when
pressurized fracturing fluids are pumped through one or
more of the angled side ports 16. The impingement
surface 50 is a portion of the exposed inner surface of the
main insert that is spaced far enough beneath the top of
the main insert that substantially none of the jet impinges
on the interface between the top of the main insert and the
main body. In other words, the main replaceable wear-
resistant insert 22 is positioned within the main bore so
that the fracturing fluids pumped through the angled side
ports generally impinge only the impingement surface 50
spaced beneath the top surface of the insert and above a
bottom surface of the insert.
As shown in FIG. 4, the fracturing head 10 may
further include one or more annular grooves 38 that are
machined into the main insert and/or the main body. These
annular grooves 38 each accommodate an O-ring for providing
a fluid-tight seal between the main insert 22 and the main
body. The O-rings inhibit fracturing fluids from
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penetrating between the main insert and the main body. As
noted above, the seals inhibit erosion of the main body and
thus prolong the service life of the fracturing head.
As shown in FIG. 4, the fracturing head 10 further
includes an auxiliary replaceable wear-resistant insert 22a
that is secured within the main bore 13 downstream of the
main insert 22. The auxiliary insert 22a includes a top
annular groove in which an O-ring is seated for providing a
fluid-tight seal between the auxiliary insert 22a and the
main insert 22. The auxiliary insert 22a also includes
three peripheral annular graoves 38 in which O-rings are
seated for providing a fluid-tight seal between the
auxiliary insert 22a and the bottom of the main body 12.
In addition, the auxiliary insert 22a includes a bottom
annular groove 40 (corresponding to an annular groove in
the top of the retainer flange 18) in which a metal ring
gasket can be seated to provide a fluid-tight seal between
the top of the retainer flange and the bottom of the
auxiliary insert.
As shown in FIG. 4, the auxiliary insert 22a is
retained within the bore 13 by a retainer ring 48 which, in
turn, is fastened to the bottom of the main body with
threaded fasteners 46: As was noted above with respect to
the previous embodiment, the retainer flange 18 is secured
to the main body 12 using fasteners that are inserted
through boreholes 42 and threaded into tapped boreholes 44.
As shown in FIG. 4, at the top of the fracturing
head 10 is a stud pad 60 having tapped boreholes 62 as well
as an annular groove in which a metal ring gasket can be
seated. The stud pad 60 permits stacking of two or more
fracturing heads.
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In one embodiment, the main body 12, retainer
flange 18, retainer ring 48 and auxiliary insert 22a are
machined from AISI 4140 heat-treated steel. The main
insert 22, against which the fracturing fluid impinges, is
machined from a harder steel such as AISI 4340 steel having
a Rockwell C Hardness of 48-56. The auxiliary insert is
made of a softer, more elastic steel which compresses more
readily than the 4340 steel of the main insert 22, and thus
permits the retainer flange to be fastened tightly to the
bottom of the main body without risk of cracking the
brittle main insert 22.
The service life of the fracturing head can be
prolonged by replacing worn inserts and/or worn annular
sealing elements. To refurbish the fracturing head, the
fracturing head is disassembled by detaching the main body
from the retainer flange. The inserts and sealing elements
can then be removed and inspected. Any worn inserts and/or
sealing elements can then be replaced before the fracturing
head is reassembled.
Persons of crdinary skill in the art will
appreciate, in light of this specification, that minor
variations may be made to the components of the fracturing
head without departing from the sprit and scope of the
invention. The embodiments of the invention described
above are therefore intended to be exemplary only and the
scope of the invention is limited only by the scope of the
appended claims.
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