Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND SYSTEM FOR TREATING A BOREHOLE
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Application No. 13/826,498
filed
on March 14,2013, which is incorporated herein by reference in its entirety.
BACKGROUND
[0002] In industries that practice in the subsurface environment, such as
hydrocarbon
recovery, carbon dioxide sequestration, etc., it is often desirable to treat
the subsurface
formation to affect various physical or chemical attributes thereof. One
specific example of
affecting physical attributes of the formation is fracturing (fracing)
procedures that help to
increase permeability of a formation.
[0003] While such procedures are commonly undertaken, they often require
extended
periods of time to complete and multiple runs in the borehole, both of which
increase costs
associated with the completion operation being undertaken. Since the art well
appreciates
new methods that improve efficiency and reduce costs, new methods for doing so
with
respect to fracturing and treating boreholes are always in demand.
SUMMARY
[0004] A method for treating an open borehole including running a tool having
axially spaced isolation band assemblies disposed thereon; pressuring on the
tool resulting in
deployment of the isolation band assemblies; applying fluid to the open
borehole between the
isolation band assemblies; and continuously moving the tool through the
borehole along a
length of the borehole while treating.
[0005] A method for drilling and fracing a borehole in a single trip including
drilling
with a bottom hole assembly (BHA) at a first end of a string, the string
including a fracing
tool upstring of the BHA, to form a borehole; deploying axially spaced
isolation band
assemblies into contact with a wall of the borehole; applying frac pressure to
the wall
between the isolation band assemblies; and continuously drawing the fracing
tool in an
uphole direction at a frac progression rate while applying the frac pressure.
[0006] A method for fracturing a borehole including running a tool having
axially
spaced isolation band assemblies disposed thereon; pressuring on the tool
resulting in
deployment of the isolation band assemblies; applying fluid to the borehole in
a zone between
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the isolation band assemblies; and continuously moving the tool through the
borehole while
fracturing the borehole with the fluid.
[0007] A system for fracturing a borehole including a tool body; two or more
isolation band assemblies spaced axially apart on the tool body; and one or
more fluid
openings in the tool body between the isolation band assemblies.
[0008] A method for fracturing a borehole including running a tool having
axially
spaced isolation band assemblies disposed thereon; pressuring on the tool
resulting in
deployment of the isolation band assemblies; applying fluid to the borehole
between the
isolation band assemblies for fracturing a downhole formation adjacent the
borehole; moving
the tool along a length of the borehole; and forming a continuous fracture
pattern in the
downhole formation along the length of the borehole.
[0009] A method for fracturing a borehole including forming an isolation zone
in the
borehole having a first length; and fracturing a downhole formation adjacent
the isolation
zone, wherein a fracture pattern of the fracturing is continuous over a second
length longer
than the first length.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The following descriptions should not be considered limiting in any
way.
With reference to the accompanying drawings, like elements are numbered alike:
[0011] Figure 1 is a schematic view of a system for performing a borehole
treatment
operation according to one embodiment disclosed herein;
[0012] Figure 2 is a schematic view of the system of Figure 1 having a pair of
isolation bands in a set configuration for treating a section of the borehole;
[0013] Figure 3 is a schematic view of the system of Figure 2 after the system
has
been moved without unsetting the isolation bands or ceasing treatment;
[0014] Figure 4 is a cross-sectional view of a tool in an initial
configuration according
to one embodiment disclosed herein;
[0015] Figure 5 illustrates the tool of Figure 4 in an intermediate open
configuration
in which isolation bands of the tool are open to fluid pressure; and
[0016] Figure 6 illustrates the tool of Figure 4 in a fully open configuration
in which
fluid communication through the tool for treating a borehole is established.
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DETAILED DESCRIPTION
[0017] A detailed description of one or more embodiments of the disclosed
apparatus
and method are presented herein by way of exemplification and not limitation
with reference
to the Figures.
[0018] Referring now to Figure 1, a system 10 is illustrated for treating a
borehole 12.
In one embodiment, the borehole 12 is an open borehole, while in other
embodiments it could
be cased, lined, cemented, etc. The system includes a tool 14 run in on a
tubular string 15. In
the illustrated embodiment, the string 15 is a drillstring having a bottom
hole assembly
(BHA) 16, which includes a drill bit 18. Advantageously, the method of the
present
invention facilitates borehole treatment such as fracing in a single run
(i.e., fracturing can be
immediately undertaken following drilling with the same string that delivered
the BHA into
the borehole, the fracing being done while withdrawing the BHA) or a separate
run, as
desired. Drilling of a borehole in a formation followed by fracturing of the
same borehole
while the drilling BHA is being tripped out of the borehole improves
efficiency and reduces
cost. In non-illustrated embodiments, the tubular string 15 could be a work
string or other
string run into the borehole 12 after a drill string is pulled out.
[0019] The tool 14 includes a pair of isolation band assemblies 20 and 22 that
can be
radially expanded, enlarged, or otherwise deployed or set in order to
sufficiently engage with
or against the borehole 12 that fracture pressure will be contained in the
target annulus axially
bounded by the isolation bands. This may in some cases be a commonly
understood seal or
in other cases may be a condition that retards leakoff to a point sufficient
to enable fracturing
prior to bleed off of pressure past the isolation band assemblies. The
isolation band
assemblies 20 and 22 are initially unset or undeployed, as illustrated in
Figure 1, in order to
promote the ability to run the tool 14 in the hole to perform drilling or
other operations. The
tool 14 includes one or more ports 24 or other fluid opening that is initially
closed, as shown
in Figure 1, to enable the string 15 to be used normally, e.g., for typical
drilling, circulation,
or other operations. The assemblies 20 and 22 are shown in a set or expanded
configuration
in Figures 2 and 3 in which isolation bands 25 and 26 of the isolation band
assemblies 20 and
22 are engaged against a wall of the borehole 12. The isolation band
assemblies 20 and 22
are transitioned between the set and unset configurations via pressure, spring
force,
mechanical coupling, etc., or combinations thereof.
[0020] By deploying the assemblies 20 and 22, isolation of a zone 28 between
the
assemblies 20 and 22 is achieved. The act of deploying the assemblies 20 and
22, discussed
in more detail below, may result in the port(s) 24 becoming opened, or the
port(s) 24 may be
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opened subsequent to deployment of the assemblies 20 and 22. Once the one or
more ports
24 is/are opened, as shown in Figure 2, a fluid or media 30 (e.g., borehole
fluid, a slurry, with
or without proppant, etc.), indicated by a set of arrows (labeled 30), may be
pumped or
delivered through the string 15 to the isolated zone 28 via the port(s) 24.
This enables the
portion of a downhole formation 32 contiguous to the zone 28 to be treated,
e.g., fractured, by
the media 30. Of course, it is again noted that while hydraulic fracturing
operations are
particularly benefitted by the illustrated embodiment, any other fluid or
media treatment
operation could be performed by the system 10.
[0021] Currently known fracing systems rely on packers that split the borehole
into a
plurality of separate isolated zones that are fractured individually (e.g.,
via frac sleeves, plug
and perf operations, etc.). Disadvantageously, these known fracturing
operations may lead to
the downhole formation not being fully fractured, i.e., in the areas proximate
to the packers
between zones.
[0022] Instead of creating a plurality of separate isolated zones that are
individually
fractured, as in the aforementioned previously known systems, the system 10 is
arranged to
continuously treat or fracture the formation 32 along an extended length 34
that is larger than
that of the zone 28. In order to facilitate the continuous treating operation,
the assemblies 20
and 22 of the tool 14 remain deployed against the borehole 12 during movement
of the tool.
For example, as noted above, the tool 14 directs fracture fluid under pressure
to the formation
32 within zone 28 as it is pulled out of the hole or moved in the uphole
direction. In this way,
the assemblies 20 and 22 can be said to be "dragged" along the borehole 12
while the tool 14
is moved by the string 15 along the length 34. The assemblies 20 and 22 can be
initially
deployed and the zone 28 initially fractured, as shown in Figure 2, and then
the tool 14
moved along the length 34 without retracting the assemblies 20 and 22 and
while applying a
pressurized fluid via the port(s) 24 to continuously fracture the entirety of
the length 34 as
shown in Figure 3. At any instantaneous moment along the length 34, only the
formation
contiguous to the zone 28 is being treated. However, as the location of the
zone 28 is
constantly moving due to the movement of the tool 14 (and "dragging" of the
assemblies 20
and 22), the entire length 34 of the formation 32 is treated over the time it
takes tool 14 to
traverse length 34.
[0023] In one embodiment, the spacing between the assemblies 20 and 22, and
thus
the size of the zone 28, is considerably smaller than the distance between the
aforementioned
statically positioned packers of known systems. Advantageously, this reduces
the
horsepower required to pump the media 30 downhole for treating or fracturing
the formation
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32. The use of smaller zones is infeasible in known systems, as the number of
packer
systems, and thus the expense of completing a borehole, would increase
drastically as the
distance between the systems is decreased. It is also noted that a fracture
pattern 36 of the
formation 32 is advantageously formed as a continuous or uniform pattern
(generally, a
"continuous pattern"). For example, as illustrated in Figure 3, there are no
regular gaps or
breaks in the fracture pattern 36 along the length 34. In contrast, currently
known system
employing statically positioned packers result in areas adjacent to the
packers that are not
fully fractured or treated, thus forming discontinuous fracture or treatment
patterns. A
continuous fracture pattern, e.g., the pattern 36, enables the more complete
extraction of
hydrocarbons or the like from the downhole formation 32. For this reason, the
system 10 or
other systems according to the current invention can also be used, as
discussed in more detail
below, to fracture or re-fracture existing wells that have already been
fractured and/or
produced, and/or which may be considered dry or depleted.
[0024] The speed or progression rate at which the tool 14 is moved can be set
in
response to the particular conditions under which the system 10 is utilized,
e.g., porosity of
the formation 32, depth, temperature, materials used for the media 30,
pressure of the media
30, frac pressure required to fracture the formation 32, etc. For example, the
progression rate
should not be so high that the media 30 does not have sufficient time to fully
penetrate,
fracture, or treat a portion of the formation 32 before the zone 28 is moved
out of range of
that portion. However, higher rates of speed will reduce the potential of the
tool 14 becoming
stuck. For example, proppant, sand, or solids in the media 30 can settle and
become wedged
between the borehole 12 and the isolation bands 25 and/or 26. Accordingly, it
may be
desirable to determine a proper progression rate based on these and other
conditions and
parameters that are determined or measured with respect to the media 30, the
borehole 12, the
tool 14, the formation 32, etc. prior to setting a speed or while the
operation is proceeding for
real time adjustment of the process.
[0025] If the isolation bands become stuck e.g., on a protuberance,
projection, or
radially restricted area of the borehole 12, and/or by proppant or other
solids becoming
wedged or lodged between the isolation bands and the wall of the borehole 12,
several actions
can be taken alone or in combination to free the tool. For example, the
isolation bands can be
refracted, e.g., by reducing the pressure internal to the string 15 used to
actuate the isolation
band assemblies, in order to permit circulation past the fractures bands in
order to clear out
settled or lodged particles and then pressure reapplied to redeploy the
isolation bands, the
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string 15 can be forced or bumped in an opposite direction and then continued
along its path
in the desired direction, etc.
[0026] It is to be appreciated that movement of the tool 14 can be halted and
resumed
any number of times for continuously treating any number of lengths of the
borehole 12, with
the length 34 designating one such length. That is, the length 34 may
correspond to the
entirety of an interval of the borehole 12 that is desired to be treated or
fractured by the
system 10, or the length 34 may be some portion of a desired interval (e.g.,
determined on-
the-fly during the treatment operation, or portions of the borehole between
joints, etc.). For
example, if the tool 14 becomes stuck, as noted above (e.g., the tool 14 needs
to be bumped,
the assemblies 20 and 22 retracted and redeployed, fluid circulated past the
assemblies 20
and/or 22, etc.), the length 34 may correspond to a distance along the
borehole 12 up to the
point at which movement of the tool 14 is halted and corrective action to free
the tool 14
occurs. As another example, movement of the tool 14 may be paused or halted if
it is
measured or determined that the pressure and/or flow rate of the media 30 is
too low (e.g.,
relatively high fluid loss occurs through a particularly soft or porous
portion of the formation
32), if the progression rate is determined during treating to be too fast, or
to otherwise ensure
a complete and effective treatment or fracture of the formation 32. In any
such case, the
length 34 again corresponds to the portion of the borehole 12 up to the point
at which
movement of the tool 14 is paused or halted.
[0027] In one embodiment, the isolation bands 25 and 26 also exert a
sufficient force
against the wall of the borehole 12 to induce stress therein that will help
the fracture process.
More particularly, the contact stress imparted to the formation 32 is
substantially equal to or
greater than the strength of the formation thus promoting sealing against the
formation while
inducing mechanical failure of the formation either alone or in combination
with the
hydraulic failure induced by pressure of the media 30 supplied by the port(s)
24 as discussed
above.
[0028] Whether the isolation bands are arranged only to retard fluid pressure
escape
from zone 28 or to induce stress, or both, the material of the isolation bands
25 and 26 is in
some embodiments selected to be resistant to disintegration or wear during
movement along
the formation while in loaded contact with the borehole 12. Exemplary
materials include
various metals, ceramics, and composites, which exhibit good strength
properties in
downhole conditions.
[0029] A tool 100 suitable for the above-discussed continuous treatment
operation is
illustrated in Figures 4-6. The tool 100 includes a pair of isolation band
assemblies 102 and
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104, similar to the assemblies 20 and 22, i.e., to engage a wall of the
borehole 12 in order to
form the zone 28 therebetween. The tool 100 also includes one or more ports
106 arranged
similarly to the port(s) 24, i.e., to provide fluid to the zone 28, e.g., for
fracturing or treating
the formation 32 contiguous to the zone 28. In this way, the tool 100 can be
generally used in
the above-described manner as tool 14.
[0030] The tool 100 is shown in an initially closed configuration in Figure 4.
In this
configuration, a sleeve 108 blocks fluid flow through the port(s) 106. The
isolation band
assemblies 102 and 104 respectively have one or more ports 110 and 112, which
ports 110
and 112 are also initially closed by the sleeve 108. A plurality of seal
elements 115, such as
0-rings, are included throughout the tool 100 to seal off unintended fluid
pathways
throughout the tool 100. The sleeve 108 can initially be held in the closed
configuration by a
release mechanism, such as a shear screw or ring, ratchet profile, magnetic
coupling, collet,
spring-loaded dog, etc., such that the sleeve 108 will not open the ports 106,
110, or 112 until
suitable force is applied to the sleeve 108. In the illustrated embodiment,
the release
mechanism takes the form of a resilient member 114, e.g., a split or
expandable ring,
disposed in both a groove or slot 116 of the sleeve 108 and a groove or slot
118 of a body or
mandrel 120 (e.g., part of the string 15 in Figures 1-3). A seat 122 is
included by the sleeve
108 and receptive of a ball, dart, plug, or other object (collectively "plug")
to enable the
aforementioned application of force for releasing the resilient member 114 or
other release
mechanism.
[0031] The tool 100 is shown in an intermediate open configuration in Figure
5.
Specifically, the sleeve 108 can be shifted by landing a plug 124 at the seat
122 and
pressurizing an internal passageway 126 of the body 120 against the plug 124.
The plug 124
can be dropped from surface and/or from a designated tool along the length of
the body 120
and/or string 15. When sufficiently pressurized, the member 114 will release
from the groove
116 and enable movement of the sleeve 108 relative to the body 120. The sleeve
108 is held
in the intermediate configuration by the resilient member 114 springing into
or resiliently
engaging with an intermediate groove or slot 128 of the body 120. When the
sleeve 108 is
shifted to the intermediate configuration, the ports 110 and 112 become
opened, i.e., in fluid
communication with the interior passageway 126 of the body 120, by movement of
an end
130 of the sleeve 108 beyond the port 110 and alignment of a port 132 in the
sleeve 108 with
the port 112.
[0032] The port 106 remains closed or blocked by the sleeve 108 in the
intermediate
configuration. To this end, a pair of isolation bands 134 and 136
corresponding respectively
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to the isolation band assemblies 102 and 104 can be deployed before the port
106 is opened.
Deployment of the isolation bands 134 and 136 is achieved in the illustrated
embodiment by
pressurizing a pair of pistons 138 and 140 corresponding respectively to the
isolation band
assemblies 102 and 104 with fluid from the passageway 126 provided to the
pistons 138 and
140 respectively via the ports 110 and 112. The pistons 138 and 140 axially
compress the
isolation bands 134 and 136, which causes the isolation bands 134 and 136 to
extend radially
outwardly to engage the borehole 12 as shown. A spring 142 or other resilient
member can
be included to initially maintain each of the isolation band assemblies 102
and 104 in their
undeployed or retracted configuration of Figure 4, and/or to urge the
isolation bands 132 and
134 to at least partially retract when the pressure in the passageway 126 is
reduced.
[0033] Similar to the isolation bands 25 and 26 discussed above, the isolation
bands
134 and 136 can be arranged to retard fluid escape, seal against the borehole,
and/or exert a
fracture force or pressure mechanically on the formation 32. The isolation
bands 134 and 136
are made of, include, or are coated by a metal, ceramic, composite, or some
other material or
combination of materials resistant to damage, wear, or disintegration of the
isolation bands
134 and 136 as they are dragged along the borehole 12 in the manner discussed
above with
respect to Figures 2 and 3. In one embodiment, the isolation bands 134 and 136
include an
elastomeric material covered by a metal or other hard material, such that the
elastomeric
material helps support the metal from buckling when highly pressured or
mechanically forced
against the borehole 12. In one embodiment, the borehole 12 is cased or lined
with relatively
smooth walled structures, and an elastomeric material, metal, or any other
suitable material is
used alone or in combination for the isolation bands. In one embodiment, the
borehole 12 has
already been completed, fractured and/or produced, and may include a cased,
lined, and/or
cemented borehole, packers, frac sleeves, perforations, cementation, or any
other currently
used fracturing device or component, and a system according to the current
invention is
utilized to re-fracture the borehole. In this way, seemingly depleted or dry
wells can be
revitalized for additional production. The isolation bands 134 and 136 may be
scored or
include slots, slits, or notches in order to ensure or encourage the isolation
bands 134 and 136
to extend in the desired direction and/or create the desired sealing profile.
For example, a
plurality of different borehole engagement profiles for the isolation bands
(e.g., pointed as
shown in Figures 5 and 6, rounded, squared off, etc.) is taught in United
States Patent No.
6,896,049to Moyes, which Patent is hereby incorporated by reference in its
entirety, and the
teachings of which are generally applicable to the operation and/or structure
of isolation band
assemblies according to various embodiments.
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[0034] In lieu of the axially compressible members shown, one of ordinary
skill in the
art will appreciate that radial deployment of isolation band assemblies could
be accomplished
in other ways. For example, the deployment could be the result of radially
expanding an
isolation band, plastically and/or elastically, e.g., with a wedge or cone,
inflating a chamber at
least partially defined by the isolation bands with a pressurized fluid, etc.
It is also noted that
the pertinent parameters of the release mechanism can be set to resist further
actuation of the
sleeve 108 until the pressure to fully set or deploy the isolation band
assemblies 102 and 104
is reached. For example, with respect to the groove 128, the depth of the
groove 128, the
angle of the edge of the groove 128, etc., can be set to resist a selected
threshold pressure. For
example, a higher pressure must be provided to release the resilient member
114 from a
relatively deeper groove and/or a groove having walls at angles approaching
perpendicularity
with the direction of movement of the sleeve 108 than if the groove 128 were
shallower or
had a more gently tapered edge.
[0035] Once a suitable pressure is reached to release the member 114 from the
groove
128, the sleeve 108 is further actuated to open the port(s) 106 by aligning
the port(s) 106 with
one or more ports 144 in the sleeve 108. The sleeve 108 is held in the fully
open
configuration of Figure 6 by way of the resilient member 114 engaging with a
groove or slot
146 in the body 120 or some other manner such as a stop. Once the port(s) 106
is opened, the
passageway 126 is in fluid communication with the zone 28 between the
assemblies 102 and
104. If the tool 100 is used in a fracturing operation, a proppant slurry can
then be
communicated to the zone 28 for fracturing the formation 32. Other fluids can
be similarly
communicated for treating the formation 32 contiguous to the zone 28.
[0036] While the invention has been described with reference to an exemplary
embodiment or embodiments, it will be understood by those skilled in the art
that various
changes may be made and equivalents may be substituted for elements thereof
without
departing from the scope of the invention. In addition, many modifications may
be made to
adapt a particular situation or material to the teachings of the invention
without departing
from the essential scope thereof. Therefore, it is intended that the invention
not be limited to
the particular embodiment disclosed as the best mode contemplated for carrying
out this
invention, but that the invention will include all embodiments falling within
the scope of the
claims. Also, in the drawings and the description, there have been disclosed
exemplary
embodiments of the invention and, although specific terms may have been
employed, they
are unless otherwise stated used in a generic and descriptive sense only and
not for purposes
of limitation, the scope of the invention therefore not being so limited.
Moreover, the use of
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the terms first, second, etc. do not denote any order or importance, but
rather the terms first,
second, etc. are used to distinguish one element from another. Furthermore,
the use of the
terms a, an, etc. do not denote a limitation of quantity, but rather denote
the presence of at
least one of the referenced item.
