U.S. patent application number 09/784290 was filed with the patent office on 2001-07-26 for methods and compositions for cementing pipe strings in well bores.
Invention is credited to Chatterji, Jiten, Cromwell, Roger S., King, Bobby J., Kuhlman, Robert D..
Application Number | 20010009133 09/784290 |
Document ID | / |
Family ID | 22936484 |
Filed Date | 2001-07-26 |
United States Patent
Application |
20010009133 |
Kind Code |
A1 |
Chatterji, Jiten ; et
al. |
July 26, 2001 |
Methods and compositions for cementing pipe strings in well
bores
Abstract
The present invention provides improved methods and compositions
for cementing pipe strings in well bores. The methods of the
invention are basically comprised of preparing a cement composition
comprised of a hydraulic cement, an epoxy resin, a hardening agent
for the epoxy resin and sufficient water to form a pumpable slurry.
Thereafter, the cement composition is introduced into the annulus
between a pipe string and a well bore and the cement composition is
allowed to set into a resilient impermeable solid mass.
Inventors: |
Chatterji, Jiten; (Duncan,
OK) ; Cromwell, Roger S.; (Walters, OK) ;
Kuhlman, Robert D.; (Duncan, OK) ; King, Bobby
J.; (Duncan, OK) |
Correspondence
Address: |
Craig W. Roddy
Halliburton Energy Services
P.O. Box 1431
Duncan
OK
73536-0440
US
|
Family ID: |
22936484 |
Appl. No.: |
09/784290 |
Filed: |
February 13, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09784290 |
Feb 13, 2001 |
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09247813 |
Feb 9, 1999 |
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Current U.S.
Class: |
106/724 |
Current CPC
Class: |
C04B 28/02 20130101;
C09K 8/473 20130101; C04B 28/02 20130101; C04B 24/281 20130101;
C04B 24/166 20130101; C04B 38/10 20130101; C04B 24/18 20130101;
C04B 24/12 20130101; C04B 24/166 20130101; C04B 24/18 20130101;
C04B 24/18 20130101; C04B 24/281 20130101; C04B 14/062 20130101;
C04B 24/166 20130101; C04B 14/062 20130101; C04B 24/281 20130101;
C04B 14/062 20130101; C04B 2103/22 20130101; C04B 2103/0005
20130101; C04B 28/02 20130101; C04B 24/18 20130101; C09K 8/46
20130101; C04B 24/18 20130101; C04B 28/02 20130101; C04B 24/281
20130101 |
Class at
Publication: |
106/724 |
International
Class: |
C04B 014/00; C04B
024/00 |
Claims
What is claimed is:
1. An improved method of cementing a pipe string in a well bore
comprising the steps of: (a) preparing a cement composition
comprised of a hydraulic cement, an epoxy resin, a hardening agent
for said epoxy resin and sufficient water to form a pumpable
slurry; (b) introducing said cement composition into the annulus
between said pipe string and said well bore; and (c) allowing said
cement composition to set into a resilient impermeable solid
mass.
2. The method of claim 1 wherein said hydraulic cement in said
composition is a Portland cement or the equivalent thereof.
3. The method of claim 1 wherein said epoxy resin in said
composition is selected from the group of a condensation reaction
product of epichlorohydrin and bisphenol A and an epoxidized
bisphenol A novolac resin and is present in an amount in the range
of from about 5% to about 20% by weight of hydraulic cement
therein.
4. The method of claim 1 wherein said hardening agent in said
composition is at least one member selected from the group of
aliphatic amines, aromatic amines and carboxylic acid anhydrides
and is present in an amount in the range of from about 0.01% to
about 0.02% by weight of hydraulic cement therein.
5. The method of claim 1 wherein said composition further comprises
a set retarding agent present in an amount in the range of from
about 0.1% to about 3% by weight of hydraulic cement therein.
6. The method of claim 1 wherein said composition further comprises
amorphous silica powder present in an amount in the range of from
about 10% to about 20% by weight of hydraulic cement therein.
7. The method of claim 1 wherein said composition further comprises
a dispersing agent present in an amount in the range of from about
0.05% to about 1% by weight of hydraulic cement in said
composition.
8. The method of claim 1 wherein said composition further comprises
a gas, a foaming agent and a foam stabilizer.
9. The method of claim 8 wherein said gas in said composition is
selected from the group of air and nitrogen and is present in said
composition in an amount sufficient to produce a composition
density in the range of from about 10 to about 16 pounds per
gallon.
10. The method of claim 8 wherein said foaming agent in said
composition is selected from the group of foaming agents comprised
of the sodium salts of alpha-olefinic sulfonic acids and mixtures
thereof and is present in an amount in the range of from about 3%
to about 5% by weight of water in said composition.
11. The method of claim 8 wherein said foam stabilizer in said
composition is selected from the group of foam stabilizers having
the formula
R--CONHCH.sub.2CH.sub.2CH.sub.2N.sup.+(CH.sub.3).sub.2CH.sub.2CO.sub.2
wherein R is a C.sub.10-C.sub.18 saturated aliphatic group, an
oleyl group or a linoleyl group and is present in an amount in the
range of from about 1.5% to about 2.5% by weight of water in said
composition.
12. An improved well cement composition comprising: a hydraulic
cement; an epoxy resin; a hardening agent for said epoxy resin; and
sufficient water to form a pumpable slurry.
13. The composition of claim 12 wherein said hydraulic cement is a
Portland cement or the equivalent thereof.
14. The composition of claim 12 wherein said epoxy resin is
selected from the group of a condensation reaction product of
epichlorohydrin and bisphenol A and an epoxidized bisphenol A
novolac resin and is present in an amount in the range of from
about 8% to about 10% by weight of hydraulic cement therein.
15. The composition of claim 12 wherein said hardening agent is at
least one member selected from the group of aliphatic amines,
aromatic amines and carboxylic acid anhydrides and is present in an
amount in the range of from about 0.01% to about 0.02% by weight of
hydraulic cement therein.
16. The composition of claim 12 which further comprises a set
retarding agent.
17. The composition of claim 16 wherein said set retarding agent is
comprised of an alkali metal or alkaline earth metal lignosulfonate
modified by reaction with formaldehyde and sodium bisulfite and is
present in an amount in the range of from about 0.1% to about 3% by
weight of hydraulic cement therein.
18. The composition of claim 12 which further comprises amorphous
silica powder present in an amount in the range of from about 10%
to about 20% by weight of hydraulic cement therein.
19. The composition of claim 12 which further comprises a
dispersing agent.
20. The composition of claim 19 wherein said dispersing agent is
the condensation reaction product of formaldehyde, acetone and
sodium bisulfite and is present in an amount in the range of from
about 0.05% to about 1% by weight of hydraulic cement in said
composition.
21. The composition of claim 12 which further comprises a gas, a
foaming agent and a foam stabilizer.
22. The composition of claim 21 wherein said gas is selected from
the group of air and nitrogen and is present in said composition in
an amount sufficient to produce a composition density in the range
of from about 10 to about 16 pounds per gallon.
23. The composition of claim 21 wherein said foaming agent is
selected from the group of foaming agents comprised of the sodium
salts of alpha-olefinic sulfonic acids and mixtures thereof and is
present in an amount in the range of from about 3% to about 5% by
weight of water in said composition.
24. The composition of claim 21 wherein said foam stabilizer is
selected from the group of foam stabilizers having the formula
R--CONHCH.sub.2CH.sub.2CH.sub.2N.sup.+(CH.sub.3).sub.2CH.sub.2CO.sub.2
wherein R is a C.sub.10-C.sub.18 saturated aliphatic group, an
oleyl group or a linoleyl group and is present in an amount in the
range of from about 1.5% to about 2.5% by weight of water in said
composition.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to cementing
subterranean wells, and more particularly, to cement compositions
which set into resilient impermeable solid masses and methods of
using the compositions.
[0003] 2. Description of the Prior Art
[0004] Hydraulic cement compositions are commonly utilized in
primary cementing operations whereby pipe strings such as casings
and liners are cemented in well bores. In performing primary
cementing, a hydraulic cement composition is pumped into the
annular space between the walls of the well bore and the exterior
surfaces of the pipe string disposed therein. The cement
composition is permitted to set in the annular space thereby
forming an annular sheath of hardened substantially impermeable
cement therein. The cement sheath physically supports and positions
the pipe string in the well bore and bonds the exterior surfaces of
the pipe string to the walls of the well bore whereby the
undesirable migration of fluids between zones or formations
penetrated by the well bore is prevented.
[0005] The cement compositions utilized in primary cementing must
often be lightweight to prevent excessive hydrostatic pressures
from being exerted on formations penetrated by well bores. A
particularly suitable technique for making a hydraulic cement
composition lightweight is to foam the cement composition with a
gas such as air or nitrogen. In primary cementing, a foamed cement
composition provides the additional advantage of being compressible
whereby formation fluids are less likely to enter the annulus and
flow through the cement composition therein during the transition
time of the cement composition, i.e., the time after the placement
of a cement composition in the annulus during which the cement
composition changes from a true fluid to a hard set mass.
[0006] The development of wells including one or more laterals to
increase production has recently taken place. Such multi-lateral
wells include vertical or deviated (including horizontal) principal
well bores having one or more ancillary laterally extending well
bores connected thereto. Drilling and completion equipment has been
developed which allows multiple laterals to be drilled from a
principal cased and cemented well bore. Each of the lateral well
bores can include a liner cemented therein which is tied into the
principal well bore. The lateral well bores can be vertical or
deviated and can be drilled into predetermined producing formations
or zones at any time in the productive life cycle of the well.
[0007] In both conventional single bore wells and multi-lateral
wells having several bores, the cement composition utilized for
cementing casing or liners in the well bores must develop high bond
strength after setting and also have sufficient resiliency, i.e.,
elasticity and ductility, to resist loss of pipe or formation bond,
cracking and/or shattering as a result of pipe movements, impacts
and/or shocks subsequently generated by drilling and other well
operations. The bond loss, cracking and/or shattering of the set
cement allows leakage of formation fluids through at least portions
of the well bore or bores which can be highly detrimental.
[0008] The set cement in a well, and particularly the set cement
forming a cement sheath in the annulus between a pipe string and
the walls of a well bore, often fails due to shear and
compressional stresses exerted on the set cement. Such stress
conditions are commonly the result of relatively high fluid
pressures and/or temperatures inside the cemented pipe string
during testing, perforating, fluid injection and/or fluid
production. The high internal pipe pressure and/or temperature
results in the expansion of the pipe string, both radially and
longitudinally, which places stresses on the cement sheath causing
it to crack or the cement bonds between the exterior surfaces of
the pipe and/or the well bore walls to fail whereby the loss of
hydraulic seal in the annulus occurs.
[0009] Another condition results from exceedingly high pressures
which occur inside the cement sheath due to the thermal expansion
of fluids trapped within the cement sheath. This condition often
occurs as a result of high temperature differentials created during
the injection or production of high temperature fluids through the
well bore, e.g., wells subjected to steam recovery or the
production of hot formation fluids from high temperature
formations. Typically, the pressure of the trapped fluids exceeds
the collapse pressure of the cement and pipe causing leaks and bond
failure.
[0010] Yet another compressional stress condition occurs as a
result of outside forces exerted on the cement sheath due to
formation shifting, overburden pressures, subsidence and/or
tectonic creep.
[0011] In multi-lateral wells wherein pipe strings have been
cemented in well bores using conventional well cement slurries
which set into brittle solid masses, the brittle set cement cannot
withstand impacts and shocks subsequently generated by drilling and
other well operations carried out in the multiple laterals without
cracking or shattering.
[0012] The above described failures can result in loss of
production, environmental pollution, hazardous rig operations
and/or hazardous production operations. The most common hazard is
the presence of gas pressure at the well head.
[0013] Thus, there are needs for improved well cement compositions
and methods whereby after setting, the cement compositions are
highly resilient and can withstand the above described stresses
without failure. That is, there is a need for well cement
compositions and methods whereby the cement compositions have
improved mechanical properties including elasticity and ductility
and failures due to pipe movement, impacts and shocks are reduced
or prevented.
SUMMARY OF THE INVENTION
[0014] The present invention provides improved methods of cementing
pipe strings in well bores and improved cement compositions that
upon setting form resilient solid masses which meet the needs
described above and overcome the deficiencies of the prior art. The
improved methods of the invention are basically comprised of the
steps of preparing an improved cement composition of this
invention, introducing the cement composition into the annulus
between a pipe string and a well bore and allowing the cement
composition to set into a resilient impermeable solid mass
therein.
[0015] The improved compositions of this invention are basically
comprised of a hydraulic cement, an epoxy resin, an epoxy resin
hardening agent and sufficient water to form a pumpable slurry. The
compositions can also optionally include amorphous silica powder, a
dispersing agent, a set retarding agent and other suitable
additives well known to those skilled in the art. Further, when
required, the densities of the cement compositions can be reduced
by foaming the compositions, i.e., including a gas, a foaming agent
and a foam stabilizer in the compositions.
[0016] It is, therefore, a general object of the present invention
to provide improved methods of cementing pipe strings in well bores
and improved cement compositions which set into resilient
impermeable solid masses.
[0017] Other and further objects, features and advantages of the
present invention will be readily apparent to those skilled in the
art upon a reading of the description of preferred embodiments
which follows.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0018] The present invention provides improved methods and
compositions for cementing pipe strings in well bores. The cement
compositions have improved resiliency without compromising strength
or fatigue resistance. While the methods and compositions are
useful in a variety of well completion and remedial operations,
they are particularly useful in primary cementing, i.e., cementing
casings and liners in well bores.
[0019] A non-foamed cement composition of this invention is
basically comprised of a hydraulic cement, an epoxy resin, a
hardening agent for the epoxy resin and sufficient water to form a
pumpable slurry. A variety of hydraulic cements can be utilized in
accordance with the present invention including those comprised of
calcium, aluminum, silicon, oxygen and/or sulfur which set and
harden by reaction with water. Such hydraulic cements include
Portland cements, pozzolana cements, gypsum cements, high aluminum
content cements, silica cements and high alkalinity cements.
Portland cements or their equivalents are generally preferred for
use in accordance with the present invention. Portland cements of
the types defined and described in API Specification For Materials
And Testing For Well Cements, API Specification 10, 5th Edition,
dated Jul. 1, 1990 of the American Petroleum Institute are
particularly suitable. Preferred API Portland cements include
classes A, B, C, G and H, with API classes G and H being more
preferred and class G being the most preferred.
[0020] A variety of hardenable epoxy resins can be utilized in the
cement compositions of this invention. Preferred epoxy resins are
those selected from the condensation products of epichlorohydrin
and bisphenol A. A particularly suitable such resin is commercially
available from the Shell Chemical Company under the trade
designation "EPON.RTM.RESIN 828." This epoxy resin has a molecular
weight of about 340 and a one gram equivalent of epoxide per about
180 to about 195 grams of resin. Another suitable epoxy resin is an
epoxidized bisphenol A novolac resin which has a one gram
equivalent of epoxide per about 205 grams of resin.
[0021] For ease of mixing, the epoxy resin utilized is preferably
pre-dispersed in a non-ionic aqueous fluid. A non-ionic aqueous
dispersion of the above described condensation product of
epichlorohydrin and bisphenol A is commercially available from the
Shell Chemical Company under the trade designation
"EPI-REZ.RTM.-3510-W-60." Another non-ionic aqueous dispersion of
an epoxy resin comprised of a condensation product of
epichlorohydrin and bisphenol A having a higher molecular weight
than the above described resin is also commercially available from
the Shell Chemical Company under the trade designation
"EPI-REZ.RTM.-3522-W-60." The above mentioned epoxidized bisphenol
A novolac resin is commercially available in a non-ionic aqueous
dispersion from the Shell Chemical Company under the trade
designation "EPI-REZ.RTM.-5003-W-55." Of the foregoing non-ionic
aqueous dispersions of epoxy resins, the aqueous dispersion of the
condensation product of epichlorohydrin and bisphenol A having a
molecular weight of about 340 and a one gram equivalent of epoxide
per about 180 to about 195 grams of resin is the most
preferred.
[0022] The epoxy resin utilized is included in the compositions of
this invention in an amount in the range of from about 5% to about
20% by weight of hydraulic cement in the composition, most
preferably in an amount of about 8% to about 10%.
[0023] A variety of hardening agents, including, but not limited
to, aliphatic amines, aliphatic tertiary amines, aromatic amines,
cycloaliphatic amines, heterocyclic amines, amidoamines,
polyamides, polyethyleneamines and carboxylic acid anhydrides can
be utilized in the compositions of this invention containing the
above described epoxy resins. Of these, aliphatic amines, aromatic
amines and carboxylic acid anhydrides are the most suitable.
[0024] Examples of aliphatic and aromatic amine hardening agents
are triethylenetetraamine, ethylenediamine,
N-cocoalkyltrimethylenediamine, isophoronediamine,
diethyltoluenediamine, and tris(dimethylaminomethylphe- nol).
Examples of suitable carboxylic acid anhydrides are
methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride,
maleic anhydride, polyazelaic polyanhydride and phthalic anhydride.
Of these, triethylenetetraamine, ethylenediamine,
N-cocoalkyltrimethylenediamine, isophoronediamine,
diethyltoluenediamine and tris(dimethylaminomethylphen- ol) are
preferred, with isophoronediamine, diethyltoluenediamine and
tris(dimethylaminomethylphenol) being the most preferred.
[0025] The hardening agent or agents utilized are generally
included in the cement compositions of this invention in an amount
in the range of from about 0.01% to about 0.02% by weight of
hydraulic cement in the compositions.
[0026] The water in the cement compositions which is in addition to
the water contained in the non-ionic aqueous dispersions of epoxy
resin is included in the compositions to make the compositions
pumpable. The water can be from any source provided it does not
contain compounds that adversely effect other components in the
cement compositions. However, fresh water is preferred. Generally,
water is present in the compositions in an amount in the range of
from about 20% to about 45% by weight of the hydraulic cement in
the compositions, more preferably in the range of from about 25% to
about 30%.
[0027] Another component which can optionally be included in the
cement compositions of this invention is a set retarding agent. Set
retarding agents are included in a cement composition when it is
necessary to extend the time in which the cement composition can be
pumped so that it will not thicken or set prior to being placed in
a desired location in the well being cemented. Examples of set
retarding agents which can be used include lignosulfonates such as
calcium and sodium lignosulfonate, such lignosulfonates modified by
reaction with formaldehyde and sodium bisulfite, organic acids such
as tartaric acid and gluconic acid, a copolymer or copolymer salt
of 2-acrylamido-2-methyl propane sulfonic acid and acrylic acid and
others. A particularly suitable set retarding agent for use in the
cement compositions of the present invention is calcium
lignosulfonate modified by reaction with formaldehyde and sodium
bisulfite. This set retarding agent is commercially available under
the trade name "HR-6L.TM." from Halliburton Energy Services, Inc.
of Duncan, Okla.
[0028] The proper amount of set retarding agent required for
particular conditions can be determined by conducting a thickening
time test for the particular set retarding agent and cement
composition. Such tests are described in the API Specification For
Materials And Testing For Well Cements, API Specification 10,
mentioned above. Generally, the set retarding agent utilized is
added to a cement composition of this invention in an amount in the
range of from about 0.1% to about 3% by weight of hydraulic cement
in the composition.
[0029] Other components which can optionally be included in the
cement compositions of this invention are amorphous silica powder
and a dispersing agent. The amorphous silica powder improves the
compressive strength and other mechanical properties of the cement
composition and the dispersing agent facilitates the dispersion of
the amorphous silica powder and other solids in the
compositions.
[0030] Suitable amorphous silica powder which can be utilized is
commercially available under the trade designation "SILICALITE.TM."
from Halliburton Energy Services, Inc. of Duncan, Okla. While
various dispersing agents can be utilized, a particularly suitable
such dispersing agent is comprised of the condensation reaction
product of formaldehyde, acetone and sodium bisulfite. This
dispersing agent is commercially available under the trade
designation "CFR-3.TM." from Halliburton Energy Services, Inc. of
Duncan, Okla.
[0031] When used, the amorphous silica powder is included in the
cement compositions of this invention in an amount in the range of
from about 10% to about 20% by weight of hydraulic cement in the
compositions. The dispersing agent used is included in the
composition in an amount in the range of from about 0.05% to about
1% by weight of hydraulic cement therein.
[0032] The above described non-foamed cement compositions of this
invention can be foamed by combining a compressible gas with the
compositions in an amount sufficient to foam the compositions and
produce a desired density along with an effective amount of a
foaming agent and an effective amount of a foam stabilizer. As
mentioned above, the presence of a compressible gas in the cement
compositions helps prevent pressurized formation fluid influx into
the cement compositions while they are setting and contributes to
the resiliency of the set cement compositions.
[0033] The gas utilized is preferably selected from nitrogen and
air, with nitrogen being the most preferred. Generally, the gas is
present in an amount sufficient to foam the cement compositions and
produce a cement composition density in the range of from about 10
to about 16 pounds per gallon, more preferably from about 12 to
about 14 pounds per gallon.
[0034] The foaming agent functions to facilitate foaming. Suitable
foaming agents are surf actants having the general formula:
H(CH.sub.2).sub.a(OC.sub.2H.sub.4).sub.bOSO.sub.3X
[0035] wherein:
[0036] a is an integer in the range of from about 5 to about
15;
[0037] b is an integer in the range of from about 1 to about 10;
and
[0038] X is any compatible cation.
[0039] A particularly preferred foaming agent of the above type is
a surfactant having the formula:
H(CH.sub.2).sub.a(OC.sub.2H.sub.4).sub.3OSO.sub.3Na
[0040] wherein:
[0041] a is an integer in the range of from about 6 to about
10.
[0042] This surfactant is commercially available under the trade
designation "CFA-S.TM." from Halliburton Energy Services, Inc. of
Duncan, Okla.
[0043] Another particularly preferred foaming agent of the above
mentioned type is a surfactant having the formula:
H(CH.sub.2).sub.a(OC.sub.2H.sub.4).sub.bOSO.sub.3NH.sub.4
[0044] wherein:
[0045] a is an integer in the range of from about 5 to about 15;
and
[0046] b is an integer in the range of from about 1 to about
10.
[0047] This surfactant is commercially available under the trade
name "HALLIBURTON FOAM ADDITIVE.TM." from Halliburton Energy
Services, Inc. of Duncan, Okla.
[0048] Another foaming agent which can be utilized in the cement
compositions of this invention includes polyethoxylated alcohols
having the formula:
[0049] H(CH.sub.2).sub.a(OC.sub.2H.sub.4).sub.bOH
[0050]
[0051] wherein:
[0052] a is an integer in the range of from about 10 to about 18;
and
[0053] b is an integer in the range of from about 6 to about
15.
[0054] This surfactant is available from Halliburton Energy
Services under the trade name "AQF-1.TM.."
[0055] Yet another foaming agent which can be used is a sodium salt
of alpha-olefinic sulfonic acid (AOS) which is a mixture of
compounds of the formulas:
X[H(CH.sub.2).sub.n--C.dbd.C--(CH.sub.2).sub.mSO.sub.3Na]
and
Y[H(CH.sub.2).sub.p--COH--(CH.sub.2).sub.qSO.sub.3Na]
[0056] wherein:
[0057] n and m are individually integers in the range of from about
6 to about 16;
[0058] p and q are individually integers in the range of from about
7 to about 17; and
[0059] X and Y are fractions with the sum of X and Y being 1.
[0060] This foaming agent is available from Halliburton Energy
Services under the trade name "AQF-2.TM.."
[0061] Still another foaming surfactant which can be used is an
alcohol ether sulfate of the formula:
H(CH.sub.2).sub.a(OC.sub.2H.sub.4).sub.bSO.sub.3NH.sub.4
[0062] wherein:
[0063] a is an integer in the range of from about 6 to about 10;
and
[0064] b is an integer in the range of from about 3 to about
10.
[0065] The particular foaming agent employed will depend on various
factors such as the types of formations in which the foamed cement
is to be placed. Generally, the foaming agent utilized is included
in a cement composition of this invention in an amount in the range
of from about 1.5% to about 10% by weight of water in the
composition. When the foaming agent is one of the preferred
surfactants described above, it is included in the composition in
an amount in the range of from about 3% to about 5% by weight of
water therein.
[0066] A foam stabilizer is also included in the foamed cement
compositions to enhance the stability of the foam. One such foam
stabilizing agent is a compound of the formula: 1
[0067] wherein:
[0068] R is hydrogen or a methyl radical; and
[0069] n is an integer in the range of from about 20 to about
200.
[0070] A particularly preferred foam stabilizing agent of the above
type is a methoxypolyethylene glycol of the formula:
CH.sub.3O(CH.sub.2CH.sub.2O).sub.nCH.sub.2OH
[0071] wherein:
[0072] n is in the range of from about 100 to about 150.
[0073] This foam stabilizing agent is commercially available from
Halliburton Energy Services under the trade designation
"HALLIBURTON FOAM STABILIZER.TM.."
[0074] The most preferred foam stabilizing agent is an
amidopropylbetaine having the formula:
R--CONHCH.sub.2CH.sub.2CH.sub.2N.sup.+(CH.sub.3).sub.2CH.sub.2CO.sub.2.sup-
.-
[0075] wherein:
[0076] R is a C.sub.10 to C.sub.18 saturated aliphatic hydrocarbon
group, an oleyl group or a linoleyl group.
[0077] A particularly suitable stabilizing agent of the above type
is a cocoylamidopropylbetaine. This foam stabilizing agent is
commercially available from Halliburton Energy Services under the
trade designation "HC-2.TM.."
[0078] The foam stabilizer is generally included in a cement
composition of this invention in an amount in the range of from
about 0.75% to about 5% by weight of water therein. When the foam
stabilizing agent is one of the particularly preferred agents
described above, it is preferably present in the composition in an
amount in the range of from about 1.5% to about 2.5% by weight of
water.
[0079] Thus, an improved well cement composition of this invention
is comprised of a hydraulic cement, an epoxy resin selected from
the group of a condensation reaction product of epichlorohydrin and
bisphenol A and an epoxidized bisphenol A novolac resin present in
an amount in the range of from about 8% to about 10% by weight of
hydraulic cement in the composition, a hardening agent for the
epoxy resin selected from the group of aliphatic amines, aromatic
amines and carboxylic acid anhydrides present in an amount in the
range of from about 0.01% to about 0.02% by weight of hydraulic
cement in the composition, and sufficient water to form a pumpable
slurry.
[0080] Another composition of the present invention is comprised of
a hydraulic cement, an epoxy resin selected from the group of a
condensation reaction product of epichlorohydrin and bisphenol A
and an epoxidized bisphenol A novolac resin present in an amount in
the range of from about 8% to about 10% by weight of hydraulic
cement in the composition, a hardening agent for the epoxy resin
selected from the group of aliphatic amines, aromatic amines and
carboxylic acid anhydrides present in the composition in an amount
in the range of from about 0.01% to about 0.02% by weight of
hydraulic cement in the composition, a set retarding agent, e.g.,
an alkali metal or alkaline earth metal lignosulfonate modified by
reaction with formaldehyde and sodium bisulfite, present in an
amount in the range of from about 0.1% to about 3% by weight of
hydraulic cement in the composition, amorphous silica powder
present in an amount in the range of from about 10% to about 20% by
weight of hydraulic cement in the composition, a dispersing agent,
e.g., the condensation reaction product of formaldehyde, acetone
and sodium bisulfite, present in an amount in the range of from
about 0.05% to about 1% by weight of hydraulic cement in the
composition and sufficient water to form a pumpable slurry.
[0081] Yet another composition of this invention is comprised of a
hydraulic cement, an epoxy resin selected from the group of a
condensation reaction product of epichlorohydrin and bisphenol A
and an epoxidized bisphenol A novolac resin present in an amount in
the range of from about 8% to about 10% by weight of hydraulic
cement in the composition, a hardening agent for said epoxy resin
selected from the group of aliphatic amines, aromatic amines and
carboxylic acid anhydrides present in an amount in the range of
from about 0.01% to about 0.02% by weight of hydraulic cement in
the composition, water present in an amount of about 25% to about
35% by weight of hydraulic cement in the composition, a gas present
in an amount sufficient to form a foam having a density in the
range of from about 12 to about 14 pounds per gallon, a foaming
agent, e.g., a sodium salt of alpha-olefinic sulfonic acid, present
in an amount in the range of from about 3% to about 5% by weight of
water in the composition and a foam stabilizer, e.g.,
cocoylamidopropylbetaine, present in an amount in the range of from
about 1.5% to about 2.5% by weight of water in the composition.
[0082] Still another composition of this invention is comprised of
a hydraulic cement, an epoxy resin selected from the group of a
condensation reaction product of epichlorohydrin and bisphenol A
and an epoxidized bisphenol A novolac resin present in an amount in
the range of from about 8% to about 10% by weight of hydraulic
cement in the composition, a hardening agent for the epoxy resin
selected from the group of aliphatic amines, aromatic amines and
carboxylic acid anhydrides present in an amount in the range of
from about 0.01% to about 0.02% by weight of hydraulic cement in
the composition, water present in an amount in the range of from
about 25% to about 35% by weight of hydraulic cement in the
composition, a set retarding agent, e.g., an alkali metal or
alkaline earth metal lignosulfonate modified by reaction with
formaldehyde and sodium bisulfite, present in an amount in the
range of from about 0.1% to about 3% by weight of hydraulic cement
in the composition, amorphous silica powder present in an amount in
the range of from about 10% to about 20% by weight of hydraulic
cement in the composition, a dispersing agent, e.g., the
condensation reaction product of formaldehyde, acetone and sodium
bisulfite, present in an amount in the range of from about 0.05% to
about 1% by weight of hydraulic cement in the composition, a gas
selected from the group of air and nitrogen present in an amount
sufficient to foam the cement composition, an effective amount of a
foaming agent, e.g., the sodium salt of an alpha-olefinic sulfonic
acid, present in an amount in the range of from about 3% to about
5% by weight of water in the composition and a foam stabilizer,
e.g., cocoylamidopropylbetaine, present in an amount in the range
of from about 1.5% to about 2.5% by weight of water therein.
[0083] As mentioned, the improved methods of the present invention
for cementing a pipe string in a well bore are basically comprised
of preparing a cement composition of the present invention as
described above, introducing the cement composition into the
annulus between a pipe string and a well bore and allowing the
cement composition to set into a resilient impermeable mass.
[0084] In order to further illustrate the methods and compositions
of this invention, the following examples are given.
EXAMPLE 1
[0085] An unfoamed composition of the present invention having a
density of 16.4 pounds per gallon was prepared by mixing 720 grams
of Premium cement with 234.6 grams of water, 58.6 grams of a
non-ionic aqueous dispersion of an epoxy resin and 0.9 grams of a
hardening agent for the epoxy resin. The cement composition was
divided into test samples and various quantities of a set retarding
agent were added to some of the test samples.
[0086] A second unfoamed cement composition of the invention having
a density of 16.4 pounds per gallon was prepared by combining 720
grams of Premium cement with 252.8 grams of water, 0.5 grams of a
dispersing agent and 80 grams of amorphous silica powder. This
cement slurry was also divided into test samples and a set
retarding agent was added to some of the test samples.
[0087] Foamed cement composition test samples were prepared by
first mixing 720 grams of premium cement with 234.6 grams of water,
58.6 grams of an aqueous dispersion of an epoxy resin and 0.9 grams
of a hardening agent. This cement slurry having a density of 16.4
pounds per gallon was divided into test samples and a set retarding
agent was added to some of the test samples. The test samples were
then foamed to a density of 14 pounds per gallon with air after
combining a foaming agent, i.e., a sodium salt of an alpha-olefinic
sulfonic acid, in an amount of about 1.67% by weight of water and a
foam stabilizer, i.e., a cocoylamidopropylbetaine, in an amount of
0.83% by weight of water with the test samples.
[0088] Additional foamed cement composition test samples were
prepared by mixing 720 grams of premium cement with 252.8 grams of
water, 0.5 grams of a dispersing agent and 80 grams of amorphous
silica powder. The resulting cement slurry having a density of 16.4
pounds per gallon was divided into test samples and various amounts
of a set retarder were added to some of the test samples. The test
samples were next foamed with air to a density of 14 pounds per
gallon after adding a foaming agent, i.e., a sodium salt of an
alpha-olefinic sulfonic acid, to the test samples in an amount of
1.67% by weight of water and a foam stabilizer, i.e., a
cocoylamidopropylbetaine to the test samples in an amount of 0.83%
by weight of water.
[0089] The test samples of the compositions of the present
invention described above were tested for thickening times at
140.degree. F. in accordance with the procedures set forth in the
API Specification 10 mentioned above. The components and their
quantities in the various cement composition test samples described
above as well as the results of the thickening time tests are given
in Table I below.
1TABLE I Cement Composition Test Sample Components, Quantities and
Thickening Times Set Amorphous Cement Retarding Epoxy Epoxy
Hardening Dispersing Silica Thickening Composition Unfoamed Foamed
Agent.sup.1, % Resin.sup.2, % Resin.sup.3, % Agent.sup.4, %
Agent.sup.5, % Powder.sup.6, % Time @ Test Sample Density, Density,
by weight by weight by weight by weight by weight by weight of
140.degree. F., No. lb/gal lb/gal of cement of cement of cement of
cement of cement cement Hr:Min 1 16.4 -- 0.32 7.2 -- 1.0 -- -- 3:05
2 16.4 -- -- -- 7.2 0.86 -- -- 3:15 3 16.4 -- 0.32 -- 7.2 1.0 0.062
10 2:35 4 16.4 -- 0.10 -- -- -- 0.062 10 -- 5 16.4 -- 0.10 -- -- --
0.062 -- -- 6 -- 14 0.32 7.2 -- 1.0 -- -- 3:45 7 -- 14 -- -- 7.2
0.86 -- -- 3:29 8 -- 14 0.32 7.2 -- 1.0 0.062 10 2:45 9 -- 14 0.10
-- 7.2 0.86 0.062 10 1:48 10 -- 14 0.10 -- -- -- 0.062 10 -- 11 --
14 0.10 -- -- -- 0.062 -- -- .sup.1Calcium lignosulfate modified by
reaction with formaldehyde and sodium bisulfite. .sup.2Non-ionic
aqueous dispersion of condensate product of epichlorohydrin and
bisphenol A ("Shell Chemical EPI-REZ.RTM.3510-W-60").
.sup.3Non-ionic aqueous dispersion of epoxidized bisphenol A
novolac resin (Shell Chemical "EPI-REZ.RTM.5003-W-55").
.sup.4Diethyltoluenediamine (Shell Chemical "EPI-CURE.RTM.W").
.sup.5Condensation product of formaldehyde, acetone and sodium
bisulfite (Halliburton "CFR-3.TM."). .sup.6Halliburton
"Silicalite.TM."
[0090] From Table I it can be seen that the thickening times of the
compositions of the present invention are within acceptable limits
for cementing pipe strings in well bores.
[0091] The cement composition test samples described above were
cured for 72 hours at 140.degree. F. Thereafter, Young's moduli,
Poisson's ratios and compressive strengths were determined under 0,
500, 1,000 and 2,000 psi confining pressures. The cement
composition test samples were also tested for Brazilian tensile
strengths and Mohr-Coulomb failure envelopes were created. The
results of these tests are set forth in Table II below.
2TABLE II Mechanical Properties of Hardened Cement Composition Test
Samples Cement Composition Young's Friction Test Sample Confining
Compressive Tensile Modulus, Poisson's Angle, No. Pressure, psi
Strength, psi Strength, psi 10.sup.6 psi Ratio degrees 1 0 9852 454
1.4 0.14 26.5 500 8634 1.4 0.20 1000 9919 1.4 0.23 2000 11532 1.0
0.19 2 0 8524 432 1.6 0.15 28 500 8247 1.3 0.20 1000 7696 0.74 0.14
2000 12557 1.1 0.16 3 0 8869 487 1.5 0.16 26 500 10047 1.4 0.13
1000 11584 1.4 0.21 2000 13896 1.4 0.27 4 0 8832 390 1.6 0.14 26.75
500 10258 1.2 0.24 1000 11958 1.3 0.19 2000 13258 0.93 0.20 5 0
8956 467 1.7 0.14 27 500 10401 1.5 0.29 1000 12166 1.6 0.28 2000
14419 1.4 0.23 6 0 2712 247 1.2 0.13 34 500 4825 0.88 0.18 1000
4978 0.75 0.20 2000 9719 1.3 0.16 7 0 3122 286 1.0 0.13 12 500 3938
0.75 0.13 1000 5297 0.95 0.16 2000 6198 0.84 0.12 8 0 4669 262 0.87
0.13 14.5 500 5094 0.95 0.25 1000 6031 1.1 0.17 2000 7849 1.0 0.16
9 0 3922 234 0.87 0.14 8 500 4607 0.81 0.25 1000 5338 0.58 0.16
2000 6490 0.14 0.18 10 0 3833 343 1.0 0.15 24.5 500 5562 1.0 0.24
1000 6600 0.74 0.20 2000 8098 0.37 0.11 11 0 3088 290 0.75 0.13
21.1 500 4074 0.78 0.23 1000 5440 0.86 0.21 2000 7364 0.72 0.18
[0092] As shown in Table II, unfoamed cement Composition Test
Sample No. 3 performed better than the other unfoamed test samples
which included epoxy resin and hardening agent. The compressive
strengths were nearly the same as unfoamed cement composition test
samples 4 and 5 which did not include epoxy resin and hardening
agent (hereinafter referred to as "neat test samples"). The elastic
properties of Test Sample No. 3 were lower, i.e., Test Sample No. 3
had an average Young's modulus of 1.43.times.10.sup.6 psi versus an
average Young's modulus of 1.53.times.10.sup.6 psi for a neat test
sample, i.e., Test Sample No. 5. Poisson's ratio for the test
samples containing epoxy resin and hardening agent, i.e., Test
Samples Nos. 1, 2 and 3 was an average of 0.18 which is
significantly lower then 0.24 for Test Sample No. 5. Test Sample
No. 1 which is similar to Test Sample No. 3 did not include
amorphous silica powder and a dispersing agent. Test Sample No. 1
performed as well as Test Sample No. 3 at lower confinements, but
had a somewhat lower strength at higher confinements. The other
test samples containing epoxy resin and hardening agent (Test
Sample Nos. 2 and 3) showed similar Young's moduli and Poisson's
ratios which means that the inclusion of epoxy resin and hardening
agent in the cement composition imparts improved elasticity.
[0093] Poisson's ratio is a measure of a body's strain growth
orthogonal to the direction of applied stress. The results shown in
Table II indicate that the cement compositions containing epoxy
resin and hardening agent will have better shear bonds with a pipe
string because it will be less flexible in lateral directions
during loading of the pipe string. Tectonic creep and subsidence of
rock formations cause increased stress loading and considerable
displacement around the well bore. The lower Poisson's ratios of
the test samples including epoxy resin and hardening agent indicate
that the set cement compositions of this invention will maintain
their original shapes. The low Young's moduli indicate that the
cement compositions will be more flexible in situations where there
are large changes in loading. Another benefit is the apparent
proclivity of a number of the test samples including epoxy resin
and hardening agent towards high toughness, allowing a large amount
of plastic creep.
[0094] As also shown in Table II, the angles of internal friction
from the Mohr-Coulomb shear failure envelopes are 20.degree. to
30.degree. which is in the range of more elastic rock. The angle of
internal friction is often a measure of a material's shear
tendency. A steep angle is interpreted as a stiff, brittle material
with high shear strength. The lower the angle of internal friction,
the lower shear strength and less stable is the tested material
under eccentric or changing compressive loads. Moderate angles of
internal friction such as those observed for the various cement
compositions including epoxy resin and hardening agent shown in
Table II indicate a more malleable, flexible material with
reasonable toughness.
[0095] Of the foamed cement composition test samples containing
epoxy resin and hardening agent, Test Sample No. 8 (equivalent to
unfoamed Test Sample No. 3) performed best. It was better than the
neat Test Sample No. 11, but slightly weaker than the neat Test
Sample No. 10 which contained amorphous silica powder and
dispersing agent. The Mohr-Coulomb failure envelope friction angles
are also considered to be of high quality. Thus, the unfoamed and
foamed cement compositions of this invention containing epoxy resin
and hardening agent can withstand a variety of loading conditions.
The cement compositions are particularly suitable for cementing
pipe strings in well bores and in multi-lateral junctions which
undergo rigorous cyclic loading, often in the form of impacts and
shocks. In addition, the resilient set cement compositions of this
invention have a better resistance to the effects of drawdown and
depletion of formations surrounding the well bore as well as to
subsidence and tectonic creep which often cause well bore failure
and casing collapse.
[0096] 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 may be
made by those skilled in the art, such changes are encompassed
within the spirit of this invention as defined by the appended
claims.
* * * * *