U.S. patent application number 10/691367 was filed with the patent office on 2005-04-28 for methods of preparing and using clean viscous well treating fluids and compositions.
Invention is credited to McCabe, Michael A., Parker, Mark, Slabaugh, Billy, Walters, Harold, Weaver, Jimmie D..
Application Number | 20050090406 10/691367 |
Document ID | / |
Family ID | 34521864 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050090406 |
Kind Code |
A1 |
McCabe, Michael A. ; et
al. |
April 28, 2005 |
Methods of preparing and using clean viscous well treating fluids
and compositions
Abstract
The present invention provides methods of preparing and using
viscous gelled well treating fluids devoid of insoluble gelling
agent residue and compositions. A viscous gelled treating fluid
composition devoid of insoluble gelling agent residue basically
comprises water, a hydrated gelling agent and the water insoluble
residue therefrom, a base for raising the pH of the water so that
the water insoluble residue is dissolved therein, and additional
water to lower the amount of the gelling agent in the treating
fluid relative to the amount of water therein and to lower the pH
thereof.
Inventors: |
McCabe, Michael A.; (Duncan,
OK) ; Weaver, Jimmie D.; (Duncan, OK) ;
Parker, Mark; (Duncan, OK) ; Slabaugh, Billy;
(Duncan, OK) ; Walters, Harold; (Duncan,
OK) |
Correspondence
Address: |
Halliburton Energy Services
Robert A. Kent
2600 S. 2nd Street
Duncan
OK
73536-0440
US
|
Family ID: |
34521864 |
Appl. No.: |
10/691367 |
Filed: |
October 22, 2003 |
Current U.S.
Class: |
507/211 |
Current CPC
Class: |
C09K 8/90 20130101; C09K
8/685 20130101; C09K 8/887 20130101; C09K 8/68 20130101 |
Class at
Publication: |
507/211 |
International
Class: |
E21B 043/00 |
Claims
What is claimed is:
1. A method of preparing a viscous gelled well treating fluid
comprising of: (a) mixing a gelling agent with water to thereby
form a viscous gelled aqueous fluid containing hydrated gelling
agent and water insoluble residue therefrom in an amount in the
range of from about 10 to about 2000 pounds of said gelling agent
per 1000 gallons of said water; (b) mixing a base with said viscous
aqueous fluid to thereby raise the pH of said fluid to in the range
of from about 10 to 13 whereby said water insoluble residue in said
fluid is at least partially dissolved therein; and then (c) adding
additional water to said viscous aqueous fluid in an amount to
thereby lower the amount of said gelling agent in said viscous
aqueous fluid relative to the amount of water therein to in the
range of from about 10 to about 80 pounds per 1000 gallons of water
and to lower the pH thereof to in the range of from about 2 to
about 12.
2. The method of claim 1 wherein said gelling agent mixed with
water in accordance with step (a) is dry particulate gelling
agent.
3. The method of claim 1 wherein said gelling agent mixed with said
water is in the form of a liquid gel concentrate.
4. The method of claim 1 wherein said water is selected from the
group consisting of fresh water and salt water.
5. The method of claim 1 wherein said gelling agent is a
polysaccharide selected from the group consisting of galactomannan
gums and derivatives thereof and modified celluloses and
derivatives thereof.
6. The method of claim 1 wherein said gelling agent is a
galactomannan selected from the group consisting of guar,
hydroxypropylguar, carboxymethylhydroxypropylguar,
carboxymethylguar, hydroxyethylguar and
carboxymethylhydroxyethylguar.
7. The method of claim 1 wherein said gelling agent is
hydroxypropylguar.
8. The method of claim 1 wherein said gelling agent is a modified
cellulose derivative selected from the group consisting of
hydroxyethylcellulose, carboxymethylhydroxyethylcellulose and
carboxymethylcellulose.
9. The method of claim 1 wherein said gelling agent is
hydroxyethylcellulose.
10. The method of claim 1 wherein said base is selected from the
group consisting of sodium hydroxide, potassium hydroxide, ammonium
hydroxide and calcium hydroxide.
11. The method of claim 1 wherein said base is sodium
hydroxide.
12. A method of treating a subterranean zone penetrated by a well
bore comprising of: (a) preparing or providing a viscous gelled
treating fluid comprising water, a hydrated gelling agent and the
water insoluble residue therefrom, a base for raising the pH of
said water so that said water insoluble residue is at least
partially dissolved therein, and additional water to lower the
amount of said gelling agent in said treating fluid relative to the
amount of water therein and to lower the pH thereof; and (b)
introducing said viscous gelled well treating fluid at least
partially devoid of insoluble gelling agent residue into said
subterranean zone.
13. The method of claim 12 wherein said water is selected from the
group consisting of fresh water and salt water.
14. The method of claim 12 wherein said gelling agent is a
polysaccharide selected from the group consisting of galactomannan
gums and derivatives thereof and modified celluloses and
derivatives thereof.
15. The method of claim 12 wherein said gelling agent is a
galactomannan selected from the group consisting of guar,
hydroxypropylguar, carboxymethylhydroxypropylguar,
carboxymethylguar, hydroxyethylguar and
carboxymethylhydroxyethylguar.
16. The method of claim 12 wherein said gelling agent is
hydroxypropylguar.
17. The method of claim 12 wherein said gelling agent is a modified
cellulose derivative selected from the group consisting of
hydroxyethylcellulose, carboxymethylhydroxyethylcellulose and
carboxymethylcellulose.
18. The method of claim 12 wherein said gelling agent is
hydroxyethylcellulose.
19. The method of claim 12 wherein said hydrated gelling agent and
said insoluble residue produced therefrom is present in said water
in an amount in the range of from about 10 to about 2000 pounds per
1000 gallons thereof.
20. The method of claim 12 wherein said base is selected from the
group consisting of sodium hydroxide, potassium hydroxide, ammonium
hydroxide and calcium hydroxide.
21. The method of claim 12 wherein said base is sodium
hydroxide.
22. The method of claim 12 wherein said base is present in said
viscous gelled treating fluid in an amount sufficient to raise the
pH of said treating fluid to in the range of from about 10 to
13.
23. The method of claim 12 wherein said additional water is present
in said viscous gelled treating fluid in an amount sufficient to
lower the amount of said gelling agent therein to in the range of
from about 10 to about 80 pounds per 1000 gallons of water and to
lower the pH thereof to in the range of from about 2 to about
12.
24. A viscous gelled treating fluid composition comprising of:
water; a hydrated gelling agent and the water insoluble residue
therefrom; a base for raising the pH of said water so that said
water insoluble residue is at least partially dissolved therein;
and additional water to lower the amount of said gelling agent in
said treating fluid relative to the amount of water therein and to
lower the pH thereof.
25. The composition of claim 24 wherein said water is selected from
the group consisting of fresh water and salt water.
26. The composition of claim 24 wherein said gelling agent is a
polysaccharide selected from the group consisting of galactomannan
gums and derivatives thereof and modified celluloses and
derivatives thereof.
27. The composition of claim 24 wherein said gelling agent is a
galactomannan selected from the group consisting of guar,
hydroxypropylguar, carboxymethylhydroxypropylguar,
carboxymethylguar, hydroxyethylguar and
carboxymethylhydroxyethylguar.
28. The composition of claim 24 wherein said gelling agent is
hydroxypropylguar.
29. The composition of claim 24 wherein said gelling agent is a
modified cellulose derivative selected from the group consisting of
hydroxyethylcellulose, carboxymethylhydroxyethylcellulose and
carboxymethylcellulose.
30. The composition of claim 24 wherein said gelling agent is
hydroxyethylcellulose.
31. The composition of claim 24 wherein said hydrated gelling agent
and said water insoluble residue therefrom is present is said
treating fluid in an amount in the range of from about 10 to about
2000 pounds of said gelling agent per 1000 gallons of said
water.
32. The composition of claim 24 wherein said base is selected from
the group consisting of sodium hydroxide, potassium hydroxide,
ammonium hydroxide and calcium hydroxide.
33. The composition of claim 24 wherein said base is sodium
hydroxide.
34. The composition of claim 24 wherein said base is present in
said viscous gelled treating fluid in an amount sufficient to raise
the pH of said treating fluid to in the range of from about 10 to
13.
35. The composition of claim 24 wherein said additional water is
present in said viscous gelled treating fluid in an amount
sufficient to lower the amount of said gelling agent therein to in
the range of from about 10 to about 80 pounds per 1000 gallons of
water and to lower the pH thereof to in the range of from about 2
to about 12.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to methods of preparing and
using clean well treating fluids, i.e., fluids devoid of insoluble
gelling agent residue, and compositions.
[0003] 2. Description of the Prior Art
[0004] Viscous gelled aqueous treating fluids are used in a variety
of treatments in oil and gas wells including well completions and
production stimulation treatments. An example of a well completion
treatment which utilizes a viscous gelled aqueous fluid is known in
the art as gravel packing. In gravel packing treatments, solid
gravel particles such as sand are carried by way of the well bore
to a subterranean zone in which a gravel pack is to be placed by a
viscous gelled aqueous carrier fluid. That is, particulate solids
(referred to in the art as gravel) are suspended in the viscous
gelled aqueous carrier fluid at the surface and are carried to the
subterranean zone in which the gravel pack is to be placed. Once
the gravel is placed in the zone, the viscous gelled aqueous
carrier fluid is broken (the viscosity is reduced) and recovered
(returned to the surface) by a delayed viscosity breaker in the
carrier fluid. The gravel pack produced functions as a filter to
separate formation solids from produced fluids while permitting the
produced fluids to flow into and through the well bore.
[0005] An example of a production stimulation treatment utilizing a
viscous gelled aqueous fluid is hydraulic fracturing. In hydraulic
fracturing, a viscous gelled aqueous fluid, referred to in the art
as a fracturing fluid, is pumped through the well bore into a
subterranean zone to be stimulated at a rate and pressure such that
fractures are formed and extended into the subterranean zone. The
fracturing fluid also carries particulate solids referred to in the
art as proppant particles into the fractures. The proppant
particles are suspended in the viscous gelled aqueous fracturing
fluid so that the proppant particles are carried into the
fractures. The viscous fracturing fluid is then broken by a delayed
viscosity breaker in the fracturing fluid so that the proppant
particles are deposited in the fractures and the fracturing fluid
is removed from the subterranean zone. The proppant particles
function to prevent the fractures from closing whereby conductive
channels are formed through which produced fluids can flow to the
well bore.
[0006] A problem with most of the viscous gelled aqueous treating
fluids used heretofore is that when the gelling agents are combined
with aqueous fluids and are hydrated, the soluble portions of the
gelling agents are dissolved in the aqueous fluids whereby the
viscosities of the fluids are increased. The insoluble portions of
the gelling agents (referred to herein as residue) such as
proteins, cellulose and fibers remain in the aqueous fluids and
enter the porosities of the subterranean zones being treated as
well as gravel packs and proppant packs in the zones whereby the
producing capabilities of the zones are impaired. Thus, there are
needs for improved methods of preparing and using well treating
fluids and compositions which are devoid of insoluble gelling agent
residue.
SUMMARY OF THE INVENTION
[0007] The present invention provides methods of preparing and
using gelled well treating fluids substantially devoid of insoluble
gelling agent residue and well treating fluid compositions which
meet the needs described above and overcome the deficiencies of the
prior art.
[0008] A method of this invention for preparing a viscous gelled
well treating fluid comprises mixing a gelling agent with water to
thereby form a viscous gelled aqueous fluid containing hydrated
gelling agent and water insoluble residue therefrom in an amount in
the range of from about 10 to about 2000 pounds of the gelling
agent per 1000 gallons of the water (preferably about 80 pounds per
gallon) provided that the viscous gelled aqueous fluid remains
flowable. The term "flowable" is used herein to mean that the fluid
has a viscosity lower than 25,000 cP as determined at 75.degree. F.
using a Brookfield RV DV-II+ viscometer using a No. 3 LV spindle at
20 rpm. A base is mixed with the viscous aqueous fluid to thereby
raise the pH of the fluid to in the range of from about 10 to 13
whereby at least a portion of the water insoluble residue in the
fluid is dissolved therein. Thereafter, additional water is added
to the viscous aqueous fluid in a quantity sufficient to lower the
amount of the gelling agent in the viscous aqueous fluid relative
to the amount of water therein to in the range of from about 10 to
about 80 pounds per 1000 gallons of water and to lower the pH
thereof to in the range of from about 2 to about 12.
[0009] A method of treating a subterranean zone penetrated by a
well bore in accordance with this invention comprises preparing or
providing a viscous gelled treating fluid comprising water, a
hydrated gelling agent and the water insoluble residue therefrom, a
residue is dissolved therein, and additional water to then lower
the amount of the gelling agent in the treating fluid relative to
the amount of water therein and to lower the pH thereof.
Thereafter, the viscous gelled well treating fluid is introduced
into the subterranean zone.
[0010] A viscous gelled treating fluid composition of this
invention comprises: water, a hydrated gelling agent and the water
insoluble residue therefrom, a base for raising the pH of the water
so that the water insoluble residue is at least partially dissolved
therein, and additional water to lower the amount of the gelling
agent in the treating fluid relative to the amount of water therein
and to lower the pH thereof.
[0011] The water utilized in the well treating fluids of this
invention can be fresh water or salt water including brines and
seawater.
[0012] Examples of the gelling agents that can be used to form the
viscous gelled aqueous fluids of this invention include, but are
not limited to, polysaccharides selected from the group consisting
of galactomannan gums and derivatives thereof and modified
celluloses and derivatives thereof. Examples of galactomannan gums
and derivatives thereof that can be utilized include, guar,
hydroxypropylguar, carboxymethylhydroxypropylguar- ,
carboxymethylguar, hydroxyethylguar and
carboxymethylhydroxyethylguar. Examples of modified celluloses and
derivatives thereof that can be used include,
hydroxyethylcellulose, carboxymethylhydroxyethylcellulose and
carboxymethylcellulose. When mixed with the water, the gelling
agent is hydrated and the soluble portions of the gelling agent are
dissolved in the water. The insoluble residue remains in the
water.
[0013] Examples of bases that can be utilized to raise the pH of
the water and to at least partially dissolve the insoluble residue
in accordance with this invention include, but are not limited to,
sodium hydroxide, potassium hydroxide, ammonium hydroxide and
calcium hydroxide.
[0014] As will now be understood, the well treating fluid
compositions of this invention have reduced levels of insoluble
gelling agent residue. As a result, when a subterranean zone is
treated using the treating fluid compositions, the producing
capabilities of the subterranean zones are not impaired.
[0015] The hydratable gelling agent that is mixed with the water
whereby the gelling agent is hydrated can be in the form of dry
gelling agent powder or in the form of a liquid gel concentrate.
Liquid gel concentrates are storable, are readily and easily
combined with water and are preferred for use in accordance with
this invention. One liquid gel concentrate that has been used
successfully heretofore comprises water, a hydratable gelling agent
that yields viscosity upon hydration and an inhibitor having the
property of reversibly reacting with the hydratable gelling agent
in a manner whereby the rate of hydration of the gelling agent is
retarded. When added to water under proper pH and/or temperature
conditions, the inhibition of the hydratable gelling agent is
reversed and a high viscosity aqueous fluid is produced. This
liquid gel concentrate is described in detail in U.S. Pat. No.
4,336,145 issued to Briscoe on Jun. 22, 1982 which is incorporated
herein by reference thereto.
[0016] Another liquid gel concentrate that can be used is comprised
of a hydrocarbon liquid, an aqueous emulsion of a suspending agent
and a water soluble gelling agent. When mixed with an aqueous
fluid, the water soluble gelling agent rapidly hydrates to yield
viscosity to the aqueous fluid. This liquid gel concentrate is
described in detail in U.S. Pat. No. 4,772,646 issued to Harms, et
al. on Sep. 20, 1988 which is incorporated herein by reference
thereto.
[0017] Yet another liquid gel concentrate that can be used is
comprised of a dry solid water-soluble gelling agent dispersed into
an oil liquid carrier. The gelling agent includes a surface coating
of a surfactant and a suspending agent to improve the
suspendability of the gelling agent in the hydrocarbon carrier
fluid. This liquid gel concentrate is described in detail in U.S.
Pat. No. 5,278,203 issued to Harms on Jan. 11, 1994 which is
incorporated herein by reference thereto.
[0018] Still another liquid gel concentrate that can be used is
referred to in U.S. Pat. No. 4,772,646 mentioned above and
incorporated herein comprises hydroxyethylcellulose, an ethyl
hexanol premix containing 1% hydroxypropylcellulose, oil and a
surfactant.
[0019] The viscous gelled treating fluids of this invention can be
utilized in a variety of well treating operations such as
fracturing subterranean producing zones, forming gravel packs in
such zones and in a variety of other operations in which viscous
well treating fluids are used. Further, the viscous gelled treating
fluids of this invention can include a variety of additives well
known to those skilled in the art such as cross-linking agents,
fluid loss control agents, dispersing agents, viscosity breakers,
bactericides, clay stabilizing agents and the like.
[0020] One embodiment of this invention for preparing a viscous
gelled well treating fluid comprises of mixing a gelling agent with
water to thereby form a viscous gelled aqueous fluid containing
hydrated gelling agent and water insoluble residue therefrom in an
amount in the range of from about 10 to about 2000 pounds of the
gelling agent per 1000 gallons of the water; mixing a base with the
viscous aqueous fluid to thereby raise the pH of the fluid to in
the range of from about 10 to 13 whereby at least a portion of the
water insoluble residue in the fluid is dissolved therein; and then
adding additional water to the viscous aqueous fluid in an amount
to thereby lower the amount of the gelling agent in the viscous
aqueous fluid relative to the amount of water therein to in the
range of from about 10 to about 80 pounds per 1000 gallons of water
and to lower the pH thereof to in the range of from about 2 to
about 12.
[0021] Another embodiment of this invention for treating a
subterranean zone penetrated by a well bore comprises of preparing
or providing a viscous gelled treating fluid comprising water, a
hydrated gelling agent and the water insoluble residue therefrom, a
base for raising the pH of the water so that the water insoluble
residue is at least partially dissolved therein, and thereafter
adding additional water to lower the amount of the gelling agent in
the treating fluid relative to the amount of water therein and to
lower the pH thereof; and introducing the viscous gelled well
treating fluid devoid of insoluble gelling agent residue into the
subterranean zone.
[0022] In one embodiment the viscous gelled treating fluid
composition comprises: water; a hydrated gelling agent and the
water insoluble residue therefrom; a base for raising the pH of the
water so that the water insoluble residue is at least partially
dissolved therein; and additional water to lower the amount of the
gelling agent in the treating fluid relative to the amount of water
therein and to lower the pH thereof.
[0023] In order to further illustrate the methods and compositions
of this invention, the following example is given.
[0024] A liquid gel concentrate is used to prepare the equivalent
of 80 lb/Mgal concentration of a gelling agent in water. A base is
added to the gelled water in order to raise the pH to above 12. The
gelled water remains at the high pH while being stored during which
gelling agent residue in the gelled water is dissolved. When
utilized, the gelled water having high pH is diluted with
additional water to reduce the concentration of the gelling agent
to the desired concentration, e.g., 30 lb/Mgal. The pH of the
gelled water is then adjusted to the desired range. Additives can
be added to the gelled water such as one or more of a surfactant, a
fluid loss control additive, a viscosity breaker, a clay stabilizer
or a crosslinker.
[0025] Thus, the present invention is well adapted to carry out the
objects and attain the ends and advantages mentioned as well as
those which are inherent therein. While numerous changes can be
made by those skilled in the art, such changes are encompassed
within the spirit of this invention as defined by the appended
claims.
* * * * *