U.S. patent application number 12/475895 was filed with the patent office on 2009-12-10 for proppant addition method and system.
Invention is credited to Brad R. Bull, Leonard Case, Roy D. Daussin, Matthew W. Oehler, Calvin L. Stegemoeller, David M. Stribling.
Application Number | 20090301725 12/475895 |
Document ID | / |
Family ID | 43067088 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090301725 |
Kind Code |
A1 |
Case; Leonard ; et
al. |
December 10, 2009 |
Proppant Addition Method and System
Abstract
A method of injecting a fracturing fluid may include
pressurizing a first fluid with clean high-pressure pumps, joining
proppant with the pressurized first fluid to form a fracturing
fluid, and moving the fracturing fluid to a wellhead and downhole
into a formation for fracturing. A pump may pressurize the proppant
without the proppant passing therethrough.
Inventors: |
Case; Leonard; (Duncan,
OK) ; Daussin; Roy D.; (Spring, TX) ;
Stegemoeller; Calvin L.; (Duncan, OK) ; Stribling;
David M.; (Duncan, OK) ; Bull; Brad R.;
(Duncan, OK) ; Oehler; Matthew W.; (Katy,
TX) |
Correspondence
Address: |
JOHN W. WUSTENBERG
P.O. BOX 1431
DUNCAN
OK
73536
US
|
Family ID: |
43067088 |
Appl. No.: |
12/475895 |
Filed: |
June 1, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61131220 |
Jun 6, 2008 |
|
|
|
Current U.S.
Class: |
166/308.1 ;
166/177.5; 166/90.1 |
Current CPC
Class: |
E21B 43/267
20130101 |
Class at
Publication: |
166/308.1 ;
166/177.5; 166/90.1 |
International
Class: |
E21B 43/26 20060101
E21B043/26; E21B 43/267 20060101 E21B043/267 |
Claims
1. A method of injecting a fracturing fluid, the method comprising:
pressurizing a first fluid with one or more clean high-pressure
pumps; joining proppant with the pressurized first fluid to form
the fracturing fluid; and moving the fracturing fluid to a wellhead
and downhole into a formation for fracturing; wherein a pump
pressurizes the proppant without passing the proppant
therethrough.
2. The method of injecting a fracturing fluid of claim 1, wherein
joining the proppant with the pressurized first fluid comprises
allowing a second pressurized fluid to pressurize the proppant.
3. The method of injecting a fracturing fluid of claim 1,
comprising passing the first fluid through fluid treatment
operations prior to pressurizing the first fluid.
4. The method of injecting a fracturing fluid of claim 1,
comprising adding one or more additives to the first fluid.
5. The method of injecting a fracturing fluid of claim 4, wherein
adding the additives occurs prior to pressurizing the first
fluid.
6. The method of injecting a fracturing fluid of claim 4, wherein
adding the additives occurs subsequent to pressurizing the first
fluid.
7. A fracturing fluid addition system comprising: one or more clean
high-pressure pumps; a proppant supply; and a fluid supply that
provides fluid for the clean high-pressure pumps to pressurize
before the fluid joins proppant from the proppant supply; wherein a
pump pressurizes the proppant without the proppant passing
therethrough.
8. The fracturing fluid addition system of claim 7, wherein the
fluid supply is a treated fluid supply.
9. The fracturing fluid addition system of claim 7, comprising a
manifold that transfers the fluid from the fluid supply to the
clean high-pressure pumps and from the clean high-pressure pumps to
a wellhead.
10. The fracturing fluid addition system of claim 7, comprising a
chemical supply that provides chemical additives to the pressurized
fluid.
11. The fracturing fluid addition system of claim 7, wherein the
proppant supply comprises a holding tank.
12. The fracturing fluid addition system of claim 7, comprising a
proppant injection system that pressurizes the proppant before the
proppant joins the pressurized fluid.
13. A method of injecting a fracturing fluid, the method
comprising: beginning a fracturing operation; pressurizing a first
fluid with one or more clean high-pressure pumps; joining premixed
proppant with the pressurized first fluid to form the fracturing
fluid; and moving the fracturing fluid to a wellhead and downhole
to a perforated zone for fracturing; wherein the premixed proppant
comprises proppant mixed with a liquid prior to the beginning of
the fracturing operation.
14. The method of injecting a fracturing fluid of claim 13, wherein
the premixed proppant is mixed at a centralized location remote
from the fracturing operation; and wherein the premixed proppant
moves from the centralized location to the fracturing operation
prior to the beginning of the fracturing operation.
15. The method of injecting a fracturing fluid of claim 13,
comprising passing the premixed proppant through one or more dirty
high-pressure pumps prior to joining the premixed proppant with the
pressurized first fluid.
16. The method of injecting a fracturing fluid of claim 13, wherein
a pump pressurizes the premixed proppant without the premixed
proppant passing therethrough.
17. The method of injecting a fracturing fluid of claim 13,
comprising adding one or more additives to the first fluid before
pressurizing the first fluid.
18. The method of injecting a fracturing fluid of claim 13,
comprising adding one or more additives to the pressurized first
fluid.
19. The method of injecting a fracturing fluid of claim 13, wherein
the premixed proppant comprises a master blend.
20. A fracturing fluid addition system comprising: one or more
clean high-pressure pumps; a proppant supply that stores premixed
proppant; and a treated fluid supply that provides fluid for the
clean high-pressure pumps to pressurize before the fluid joins
premixed proppant from the proppant supply; wherein the premixed
proppant comprises proppant mixed with a liquid and stored in the
proppant supply until the beginning of a fracturing operation.
21. The fracturing fluid addition system of claim 20, comprising a
manifold that transfers the fluid from the treated fluid supply to
the clean high-pressure pumps and from the clean high-pressure
pumps to a wellhead.
22. The fracturing fluid addition system of claim 20, comprising a
chemical supply that provides chemical additives to the pressurized
fluid.
23. The fracturing fluid addition system of claim 20, wherein the
proppant supply comprises a holding tank.
24. The fracturing fluid addition system of claim 20, comprising a
proppant injection system that pressurizes the proppant before
proppant joins the pressurized fluid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/131,220, filed Jun. 6, 2008,
entitled "Method of Fracturing Subterranean Formations Utilizing
High Efficiency Fracturing Fluids and Apparatus Therefore," and is
related to co-pending U.S. application Ser. No. ______ (Attorney
Docket No. HES 2008-IP-012563U1) entitled "Methods of Treating
Subterranean Formations Utilizing Servicing Fluids Comprising
Liquefied Petroleum Gas and Apparatus Thereof" filed concurrently
herewith, the entire disclosures of which are incorporated herein
by reference.
BACKGROUND
[0002] The present invention relates to methods of injecting a
fracturing fluid into a well bore and, more particularly, in
certain embodiments, to methods of injecting proppant downstream of
clean high-pressure pumps.
[0003] In conventional fracturing operations as shown in FIG. 1,
dirty high-pressure pumps 100 connect to central manifold 102.
"High-pressure pumps" generally refer to pumps pumping 1,000 psi or
more. Dirty high-pressure pumps 100 are high-pressure pumps through
which fracturing fluid, including proppant and/or other abrasive
material, passes. The proppant may be sand, manmade proppant
particulates, sawdust, nutshells, or any other material a person
having ordinary skill in the art would find useful for fracturing
operations. Manifold 102 may be a trailer system that transfers
high-pressure fracturing fluid to wellhead 104 and downhole to a
perforated zone for fracturing.
[0004] Manifold 102 may also transfer fracturing fluid from at
least one fluid treatment blender 106 to dirty high-pressure pumps
100. Fluid treatment blender 106 generally combines gelling agents,
chemical additives from chemical storage 136, and dry proppant at
relatively low pressures. The gelling agent solution typically
hydrates with water from potable/treated water supply 108 and
pre-blends in separate pregel blender 110 before pumping to fluid
treatment blender 106. At fluid treatment blender 106, proppant
meters from proppant supply 112 into the remaining mixture to
become a fracturing fluid that feeds into dirty high-pressure pumps
100. Thus, dirty high-pressure pumps 100 are subject to erosive and
abrasive forces resulting from proppant-laden ("dirty") fluids.
[0005] In this configuration, all dirty high-pressure pumps 100
intake fracturing fluid having about 0.5-10 pounds of proppant per
gallon of fluid. In some operations such as WaterFrac operations,
the proppant concentrations may be as low as 0.1 pounds per gallon.
Erosion in dirty high-pressure pumps 100 may be particularly
problematic for valves, seats, and fluid ends. In many cases,
maintenance on high-pressure pump consumables may be so frequent as
to affect utilization rates by more than 20%.
[0006] The concentration of abrasive materials, for example,
proppant, in a fluid, along with fluid velocity has an enormous
impact on maintenance costs for dirty high-pressure pumps 100. By
way of example, the relative maintenance cost of pumping a fluid
with about 1.5 pounds of 10-20 sand per gallon may be 7 times
greater than pumping an abrasive-free fluid; and the maintenance
cost of pumping a fluid with about 1 pound of 20-40 UCAR proppant
per gallon may be 34 times greater than pumping an abrasive-free
fluid.
[0007] "Split-fluid-flow" is another known configuration for
fracturing operations including WaterFrac operations.
Split-fluid-flow as shown in FIG. 2 involves so-called "clean" and
"dirty" high-pressure pumps, 114 and 100 respectively. In this
context, clean pumps 114 pump "clean" fluids or those without
proppant, while dirty pumps 100 pump "dirty" fluids, or those that
are slurry-laden or have proppant therein. Depending on the
configuration of a particular job, a given pump may be used as
either a clean pump or a dirty pump. Thus, the same pump may be a
clean pump for one job and a dirty pump for the next, or vice
versa.
[0008] With split-fluid-flow, dry proppant from proppant supply
112, gelling agent solution from pregel blender 110, water or other
treated fluid from potable/treated fluid supply 108, and chemical
additives from chemical storage 136 combine in fluid treatment
blender 106 before passing through dirty high-pressure pumps 100.
The concentrations of these materials, however, are higher than in
the more typical fracturing operations because the split-fluid-flow
configuration is such that only a fraction of total fluid flow
going to wellhead 104 contains proppant. The other portion of the
split-fluid-flow may be comprised of simply water optionally with
chemicals such as friction reducers. This water need not be from
potable/treated fluid supply 108, but instead may be untreated
produced or returned water, or other types of water from untreated
fluid supply 118. Boost pump 138 may draw water or other fluid from
untreated fluid supply 118, pass it through optional fluid
treatment operations 140, and pump it to clean high-pressure pumps
114. Fluid treatment operations 140, when present, may include
bacteria control, reducing solids, fluid clarification, removing
suspended solids, chemical treatment, ion removal, or any of a
number of other treatments.
[0009] Each of these separate streams, that is, the clean and dirty
streams, passes independently through respective high-pressure
pumps, 114 and 100. By separating the clean and dirty high-pressure
pumps, 114 and 100, the overall abrasive effects of the proppant
may diminish, and consequently, the maintenance costs may lessen.
Additionally, fluid treatment blender 106 may be smaller in
split-fluid-flow operations than in conventional fracturing
operations.
[0010] However, even split-fluid-flow operations require job
critical dry proppant handling, metering and mixing equipment at
the jobsite. This dry proppant also requires transport to and
storage on location. The equipment involved can be complicated,
costly, and prone to failure due to the number of job critical
systems and components involved.
SUMMARY
[0011] In some embodiments, a method of injecting a fracturing
fluid may include pressurizing a first fluid with one or more clean
high-pressure pumps, joining proppant with the pressurized first
fluid to form the fracturing fluid, and moving the fracturing fluid
to a wellhead and downhole into a formation for fracturing, wherein
a pump pressurizes the proppant without passing the proppant
therethrough.
[0012] In other embodiments, a fracturing fluid addition system may
comprise one or more clean high-pressure pumps, a proppant supply,
and a fluid supply that provides fluid for the clean high-pressure
pumps to pressurize before the fluid joins proppant from the
proppant supply. A pump may pressurize the proppant without the
proppant passing therethrough.
[0013] In other embodiments, a method of injecting a fracturing
fluid may include beginning a fracturing operation, pressurizing a
first fluid with one or more clean high-pressure pumps, joining
premixed proppant with the pressurized first fluid to form the
fracturing fluid, and moving the fracturing fluid to a wellhead and
downhole to a perforated zone for fracturing. The premixed proppant
may include proppant mixed with a liquid prior to the beginning of
the fracturing operation.
[0014] In other embodiments, a fracturing fluid addition system may
include one or more clean high-pressure pumps, a proppant supply
that stores premixed proppant, and a treated fluid supply that
provides fluid for the clean high-pressure pumps to pressurize
before the fluid joins premixed proppant from the proppant supply.
The premixed proppant may include proppant mixed with a liquid and
stored in the proppant supply until the beginning of a fracturing
operation.
[0015] The features and advantages of the present invention will be
readily apparent to those skilled in the art. While those skilled
in the art may make numerous changes, such changes are within the
spirit of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a schematic of a conventional fracturing
operation.
[0017] FIG. 2 illustrates a schematic of a split-fluid-flow
fracturing operation.
[0018] FIG. 3 illustrates a schematic of a fracturing operation
using only clean high-pressure pumps in accordance with embodiments
of the present invention.
[0019] FIG. 4 illustrates a schematic of a proppant injection
system in accordance with embodiments of the present invention.
[0020] FIG. 5 illustrates a schematic of a modified
split-fluid-flow fracturing operation in accordance with
embodiments of the present invention.
[0021] FIG. 6 illustrates a schematic of a modified
split-fluid-flow fracturing operation in accordance with
embodiments of the present invention.
[0022] FIG. 7 illustrates a schematic of a fracturing operation
using only clean high-pressure pumps in accordance with embodiments
of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0023] Referring to FIG. 3, fluid treatment system 116 may supply
water or other fluid, proppant, gels, and other chemical additives
to wellhead 104. In the embodiment of FIG. 3, fluid treatment
system 116 may include pregel blender 110, untreated fluid supply
118, fluid treatment blender 106, chemical storage 136, manifold
102, a number of clean high-pressure pumps 114, and proppant supply
112. Untreated fluid supply 118 may contain fluid, which need not
be potable/treated water, but instead may be untreated produced or
returned water, or other types of fluid. Boost pump 138 may draw
fluid from untreated fluid supply 118 before passing it through
optional fluid treatment operations 140 to fluid treatment blender
106, where it may combine with gels from pregel blender 110 and
other chemical additives from chemical storage 136. The mixture in
pregel blender 110 may include chemical additives such as friction
reducing agents, gelling agents, clay control agents, surfactants,
bactericides, gas permeability agents, and the like. Such chemical
additives may move from pregel blender 110 to fluid treatment
blender 106 and blend with water or other fluid before moving to
clean high-pressure pumps 114 via manifold 102. While this
embodiment includes both pregel blender 110 and fluid treatment
blender 106, depending on the job, either or both may be omitted.
Clean high-pressure pumps 114 may pressurize the fluid. After
passing through clean high-pressure pumps 114, the pressurized
fluid may join proppant from proppant supply 112, forming a
fracturing fluid. The fracturing fluid may then move through
manifold 102 to wellhead 104 and downhole to a perforated zone for
fracturing. By providing for the addition of proppant after the
fluid has passed through clean high-pressure pumps 114, life
expectancy and reliability of the pumps may improve, and
maintenance costs may diminish over traditional methods involving
erosive and abrasive forces caused by proppant-laden fluids passing
through dirty high-pressure pumps 100. Additionally, this method
may allow for independent optimization of operations. In other
words, the operator may separately optimize the high-pressure
pumping operations and abrasive additive operations.
[0024] In some embodiments, clean high-pressure pumps 114 may be
staged centrifugal pumps, or positive displacement pumps, but other
types of pumps may also be appropriate. In some embodiments,
proppant supply 112 may be a high-pressure liquid sand injection
system comprising a HT-400-type pump, but other supply mechanisms
are also within the scope of this invention.
[0025] In addition to improving the life of clean high-pressure
pumps 114 and reducing downtime, the methods disclosed herein may
allow for a reduction in the size of manifold 102, leading to a
quicker rig-up time. An easier rig-up may additionally reduce
injuries on location. Further, the number of pumps on location may
lessen, as the need for backup horsepower may diminish with pumps
that are more reliable. Finally, injecting wet proppant downstream
of clean high-pressure pumps may lead to a reduction of equipment
on location because the proppant/fluid mixture may be a premix from
some other location, which has arrived at the well location in
transports. This mixture may then offload to the proppant injector
and move directly into the high-pressure fluid stream.
[0026] An operator may choose any of a number of methods to inject
proppant into the high-pressure stream. In some embodiments, clean
high-pressure pumps 114 may pressurize proppant without actually
passing proppant therethrough. Referring now to FIG. 4, proppant
injection system 142 may include at least one high-pressure chamber
120 may be divided by a plunger or floating piston 132 such that
pressure from a clean fluid in clean high-pressure line 127 may
transfer to dirty fluid. In other words, pressurized fluid may
pressurize the proppant, which may be part of a proppant laden
fluid. As illustrated, this may be at a 1:1 ratio. However, other
ratios may also be suitable, depending on the job conditions.
Multiple high-pressure chambers 120 may allow for continual
introduction of proppant through fill line 124, through
high-pressure chamber 120, and into high-pressure stream 126 going
to wellhead 104.
[0027] Still referring to FIG. 4, proppant may move from proppant
supply 112 (not shown in FIG. 4) into proppant fill line 124 at low
pressure. In some embodiments, proppant may be liquid-prop or
master blend from proppant storage 134 (shown and discussed with
respect to FIGS. 5-8). In other embodiments, proppant may move from
a blender. Proppant injection system 142 may have an electric over
hydraulic control system with poppet or other types of valves for
check valves and relief valves.
[0028] Proppant fill line 124 may supply proppant with a minimum
constant pressure. One or more high-pressure chambers 120 may open
to atmospheric pressure via valves 122 in bleed line 128, such that
the pressure supplied in proppant fill line 124 may be sufficient
to open respective check valve(s) 130 and move respective floating
piston(s) 132. When a high-pressure chamber 120 sufficiently fills,
corresponding control valve 122 to bleed line 128 may close and
corresponding control valve 122 to clean high-pressure line 127 may
open. Since floating piston 132 floats, the pressure may equalize.
The high pressure on the proppant-laden fluid may then push the
fluid through corresponding check valve 130 into high-pressure
stream 126 going to wellhead 104. The pressure differential across
floating piston 132 may only be enough to overcome piston friction,
unless floating piston 132 seats when filling with proppant. In
this case, the pressure may be equivalent to the supply pressure of
the proppant-laden fluid. A pressure relief valve on clean
high-pressure line 127 may prevent a large pressure differential if
floating piston 132 seats on the power stroke. The volume available
in each high-pressure chamber 120 and the number of high-pressure
chambers 120 may be sufficient to allow continuous injection of
proppant into high-pressure stream 126 going to wellhead 104. Thus,
all high-pressure pumps on location may be clean high-pressure
pumps 114.
[0029] In various other embodiments, proppant may move from
proppant supply 112 into high-pressure stream 126 going to wellhead
104. In other words, proppant may enter downstream, or on the
high-pressure side, of clean high-pressure pumps 114. For example,
proppant may move from proppant supply 112 via a parallel series of
high-pressure tanks that may valve through a manifold. In another
embodiment, proppant may move via a piston at the bottom of an
addition container. In another embodiment, proppant may move from
proppant supply 112 via a staged plunger-type injection with wet
sand. In still another embodiment, proppant may move from proppant
supply 112 via a high-pressure eductor for sand injection.
[0030] In some embodiments, injecting proppant from proppant supply
112 may involve a proppant suspended within a solution of liquid
prior to the beginning of the fracturing operation. Such proppant
slurry mixtures may be mixed onsite or offsite and may be high
concentration solutions, e.g., 20 pounds per gallon and greater. In
some embodiments, the proppant may mix with liquid offsite. In
other embodiments, the proppant may mix onsite, but before the
start of the job. Thus, the fracturing process may proceed without
handling, metering, or mixing dry proppant during fracturing.
[0031] The method illustrated in FIG. 5 utilizes a
split-fluid-flow, having corresponding clean and dirty high-power
pumps, 114 and 100, and benefits from the advantages of lower
equipment wear, increased reliability, etc. However, it differs
from conventional split-fluid-flow methods because it involves
different method of transport, handling, metering, and mixing of
the proppant. In this embodiment, the proppant may be a premixed
proppant, such as a concentrated, job specific slurry, mixed either
on location before the job, or at a mixing station at a centralized
location before transport to the jobsite as "liquid-prop." The
centralized location may be remote from the pad of a particular
fracturing operation and a single centralized mixing station may
supply several frac spreads. Tankers may transport the liquid-prop
to the jobsite and pump it into holding tank 134, instead of
pneumatic transport trailers trucking dry proppant to mountain
movers at the jobsite. Alternatively, pipelines may transport the
liquid-prop to the pad prior to the commencement of the fracturing
operation. The liquid-prop may then move to dirty high-pressure
pumps 100, for example, via booster pump (not shown), upon
commencement of the job. Potable/treated fluid supply 108 may
provide water or other fluid to pregel blender 110, which may
provide gel and chemical additives from chemical supply 136 to
fluid treatment operations 140, without the need for a separate
fluid treatment blender 106 as is typically required. The flow rate
of dirty high-pressure pumps 100 may vary to provide the desired
proppant concentration downhole. The "clean" portion of this
embodiment of a split-fluid-flow may be substantially the same as
described above with respect to FIG. 2. The use of a centralized
mixing station may reduce or eliminate the need for mountain movers
and/or fluid treatment blender 106. By reducing the equipment
required, the space required for a fracturing operation may
contract, along with the number of operators. Additionally,
reduction in equipment can increase reliability of the job by
reducing the difficulties associated with job critical equipment.
The centralized mixing station may also enhance the accuracy of the
mixture because the weighing and dosing equipment may be stationary
and the mixing time and personnel may be independent of the job
schedule. The use of stationary equipment instead of mobile
conveying, metering, and mixing equipment may also require lower
capital investment. In addition to being less expensive, stationary
equipment may be capable of supplying several frac spreads.
[0032] Similar to liquid-prop, other premixed proppants, such as
concentrated liquid sand compositions may be prepared and
transported to the well site in advance. Some such compositions may
be high solids content slurries that may be substantially stable
and may not substantially settle prior to admixing with treatment
fluid.
[0033] In yet another alternative embodiment, premixed proppants
may include a master blend that may be mixed either offsite or in
advance on-site. This master blend may include proppant, gelling
agents, friction reducers, and any other chemical additives needed
in a single concentrated mixture. In other words, in addition to
liquid and sand, the master blend may include of all chemicals and
gelling agents needed for a fracturing stage containing proppant.
For example, the master blend may contain corrosion inhibitors,
biocides, and clay control surfactants. Such a master blend may
allow for operations that are more efficient and minimize equipment
at the well site, including equipment for blending operations.
[0034] In one embodiment, split-fluid-flow fracturing
configurations may use the master blend. FIG. 6 illustrates a
configuration without the need for fluid treatment blender 106 or
pregel blender 110. The master blend may move from holding tank 134
directly to dirty high-pressure pumps 100. The movement of the
master blend may occur at the same time as water or other fluid
moves from potable/treated fluid supply 108 to fluid treatment
operations 140 and chemical additives move from chemical storage
136 directly to dirty high-pressure pumps 100. The chemicals may
move via a chemical addition system (not shown). Alternatively, a
simple t-mixer prior to dirty high-pressure pumps 100 may be
sufficient for mixing of the chemicals into the water or other
fluid used for fracturing. The "clean" portion of this embodiment
of a split-fluid-flow may be substantially the same as described
above with respect to FIG. 2.
[0035] In the embodiment illustrated in FIG. 7, only clean
high-pressure pumps 114 are used. In this particular configuration,
centrifugal and/or staged pumps may be advantageous, depending on
the pressure required. The master blend, dry proppant, or other
proppant may move from proppant supply 112 or holding tank 134 (not
shown), through proppant injection system 142, and into
high-pressure stream 126 downstream of clean high-pressure pumps
114. While proppant injection system 142 is illustrated in FIG. 7,
a staged centrifugal pump (not shown) or other types of injection
may be used. In fracturing stages that do not contain proppant,
chemicals may also move into high-pressure stream 126 from chemical
storage 136, via chemical injection system 145. Chemical injection
system 145 may operate in a manner similar to that of proppant
injection system 142, or may be any other type of injection system.
Thus, the embodiment depicted in FIG. 7 may eliminate the need for
fluid treatment blender 106, pregel blender 110, transport,
storage, and conveyance of dry proppant, and dirty high-pressure
pumps 100. Further, the embodiment depicted in FIG. 7 may allow for
injection remote from manifold 102 and clean high-pressure pumps
114. For example, chemicals and proppant may be injected at a pad
remote from the pad of the manifold and pumps. In some embodiments,
the distance between the pads may be about a mile or more.
Alternatively, proppant supply 112 and chemical storage 136 may be
coordinated units, used in conjunction with, and situated on the
same pad as manifold 102.
[0036] The term "proppant" may include any of a number of
particulates suitable for use in the present invention, which may
be comprised of any material suitable for use in subterranean
operations. Suitable particulate materials include, but are not
limited to, sand; bauxite; ceramic materials; glass materials;
polymer materials; Teflon.RTM. materials; nut shell pieces; seed
shell pieces; cured resinous particulates comprising nut shell
pieces; cured resinous particulates comprising seed shell pieces;
fruit pit pieces; cured resinous particulates comprising fruit pit
pieces; wood; composite particulates and combinations thereof.
Composite particulates may also be suitable, suitable composite
materials may comprise a binder and a filler material wherein
suitable filler materials include silica, alumina, fumed carbon,
carbon black, graphite, mica, titanium dioxide, meta-silicate,
calcium silicate, kaolin, talc, zirconia, boron, fly ash, hollow
glass microspheres, solid glass, and combinations thereof.
Typically, the particulates have a size in the range of from about
two to about 400 mesh, U.S. Sieve Series. In particular
embodiments, preferred particulates size distribution ranges are
one or more of 6/12 mesh, 8/16, 12/20, 16/30, 20/40, 30/50, 40/60,
40/70, or 50/70 mesh. It should be understood that the term
"particulate," as used in this disclosure, includes all known
shapes of materials including substantially spherical materials,
fibrous materials, polygonal materials (such as cubic materials)
and mixtures thereof. Moreover, fibrous materials that may or may
not bear the pressure of a closed fracture are often included in
proppant and gravel treatments.
[0037] Generally, the teachings of the present invention may use
any treatment fluid suitable for a fracturing, gravel packing, or
frac-packing application, including aqueous gels, viscoelastic
surfactant gels, oil gels, foamed gels, and emulsions. Suitable
aqueous gels are generally comprised of water and one or more
gelling agents. Suitable emulsions can be comprised of two
immiscible liquids such as an aqueous liquid or gelled liquid and a
hydrocarbon. The addition of a gas, such as carbon dioxide or
nitrogen may create foams. In exemplary embodiments of the present
invention, the fracturing fluids are aqueous gels comprised of
water, a gelling agent for gelling the water and increasing its
viscosity, and, optionally, a crosslinking agent for crosslinking
the gel and further increasing the viscosity of the fluid. The
increased viscosity of the gelled, or gelled and cross-linked,
treatment fluid, inter alia, reduces fluid loss and allows the
fracturing fluid to transport significant quantities of suspended
proppant particles. The water used to form the treatment fluid may
be fresh water, salt water, brine, seawater, or any other aqueous
liquid that does not adversely react with the other components. The
density of the water can increase to provide additional particle
transport and suspension in the present invention.
[0038] A useful variety of gelling agents may include hydratable
polymers that contain one or more functional groups such as
hydroxyl, carboxyl, sulfate, sulfonate, amino, or amide groups.
Suitable gelling typically comprises polymers, synthetic polymers,
or a combination thereof. A variety of suitable gelling agents for
use in conjunction with the methods and compositions of the present
invention, include, but are not limited to, hydratable polymers
that contain one or more functional groups such as hydroxyl,
cis-hydroxyl, carboxylic acids, and derivatives of carboxylic
acids, sulfate, sulfonate, phosphate, phosphonate, amino, or amide.
In certain exemplary embodiments, the gelling agents may be
polymers comprising polysaccharides, and derivatives thereof that
contain one or more of these monosaccharide units: galactose,
mannose, glucoside, glucose, xylose, arabinose, fructose,
glucuronic acid, or pyranosyl sulfate. Examples of suitable
polymers include, but are not limited to, guar gum and derivatives
thereof, such as hydroxypropyl guar and carboxymethylhydroxypropyl
guar, and cellulose derivatives, such as hydroxyethyl cellulose.
Additionally, synthetic polymers and copolymers that contain the
above-mentioned functional groups may be used. Examples of such
synthetic polymers include, but are not limited to, polyacrylate,
polymethacrylate, polyacrylamide, polyvinyl alcohol, and
polyvinylpyrrolidone. In other exemplary embodiments, the gelling
agent molecule may be depolymerized. The term "depolymerized," as
used herein, generally refers to a decrease in the molecular weight
of the gelling agent molecule. U.S. Pat. No. 6,488,091 issued Dec.
3, 2002 to Weaver, et al., the relevant disclosure of which
incorporates herein by reference, describes depolymerized gelling
agent molecules. Suitable gelling agents generally are present in
the viscosified treatment fluids of the present invention in an
amount in the range of from about 0.1% to about 5% by weight of the
water therein. In certain exemplary embodiments, the gelling agents
are present in the viscosified treatment fluids of the present
invention in an amount in the range of from about 0.01% to about 2%
by weight of the water therein.
[0039] Crosslinking agents may be used to crosslink gelling agent
molecules to form crosslinked gelling agents. Crosslinkers
typically comprise at least one ion that is capable of crosslinking
at least two gelling agent molecules. Examples of suitable
crosslinkers include, but are not limited to, boric acid, disodium
octaborate tetrahydrate, sodium diborate, pentaborates, ulexite and
colemanite, compounds that can supply zirconium IV ions (such as,
for example, zirconium lactate, zirconium lactate triethanolamine,
zirconium carbonate, zirconium acetylacetonate, zirconium malate,
zirconium citrate, and zirconium diisopropylamine lactate);
compounds that can supply titanium IV ions (such as, for example,
titanium lactate, titanium malate, titanium citrate, titanium
ammonium lactate, titanium triethanolamine, and titanium
acetylacetonate); aluminum compounds (such as, for example,
aluminum lactate or aluminum citrate); antimony compounds; chromium
compounds; iron compounds; copper compounds; zinc compounds; or a
combination thereof. An example of a suitable commercially
available zirconium-based crosslinker is "CL-24" available from
Halliburton Energy Services, Inc., Duncan, Okla. An example of a
suitable commercially available titanium-based crosslinker is
"CL-39" available from Halliburton Energy Services, Inc., Duncan
Okla. Suitable crosslinkers generally are present in the
viscosified treatment fluids of the present invention in an amount
sufficient to provide, inter alia, the desired degree of
crosslinking between gelling agent molecules. In certain exemplary
embodiments of the present invention, the crosslinkers may be
present in an amount in the range from about 0.001% to about 10% by
weight of the water in the fracturing fluid. In certain exemplary
embodiments of the present invention, the crosslinkers may be
present in the viscosified treatment fluids of the present
invention in an amount in the range from about 0.01% to about 1% by
weight of the water therein. Individuals skilled in the art, with
the benefit of this disclosure, will recognize the exact type and
amount of crosslinker to use depending on factors such as the
specific gelling agent, desired viscosity, and formation
conditions.
[0040] The gelled or gelled and cross-linked treatment fluids may
also include internal delayed gel breakers such as enzyme,
oxidizing, acid buffer, or temperature-activated gel breakers. The
gel breakers cause the viscous treatment fluids to revert to thin
fluids for production back to the surface after use to place
proppant particles in subterranean fractures. The gel breaker used
is typically present in the treatment fluid in an amount in the
range of from about 0.5% to about 10% by weight of the gelling
agent. The treatment fluids may also include one or more of a
variety of well-known additives, such as gel stabilizers, fluid
loss control additives, clay stabilizers, bactericides, and the
like.
[0041] While the term "fracturing" as used herein generally refers
to conventional fracturing operations, it may include frac pack
operations or any of a number of other treatments, comprising
fracturing. Additionally, the methods of this disclosure may be
used for non-fracturing operations.
[0042] Therefore, the present invention is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. The particular embodiments disclosed above are
illustrative only, as those skilled in the art, having the benefit
of the teachings herein may modify and practice the invention in
different but equivalent manners. Furthermore, the details of
construction or design herein shown do not provide limitations,
other than as described in the claims below. It is therefore
evident that the particular illustrative embodiments disclosed
above may be altered or modified and all such variations fall
within the scope and spirit of the present invention. All numbers
and ranges disclosed above may vary by any amount (e.g., 1 percent,
2 percent, 5 percent, or, sometimes, 10 to 20 percent). Whenever a
numerical range with a lower limit and an upper limit appears, any
number and any included range falling within the range are
specifically disclosed. In particular, every range of values (of
the form, "from about a to about b," or, equivalently, "from
approximately a to b," or, equivalently, "from approximately a-b")
disclosed herein is to be understood to set forth every number and
range encompassed within the broader range of values. Moreover, the
indefinite articles "a" or "an," as used in the claims, are defined
herein to mean one or more than one of the element that it
introduces. In addition, the terms in the claims have their plain,
ordinary meaning unless otherwise explicitly and clearly defined by
the patentee.
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