CA1253680A - Method of cementing a subterranean zone - Google Patents
Method of cementing a subterranean zoneInfo
- Publication number
- CA1253680A CA1253680A CA000568264A CA568264A CA1253680A CA 1253680 A CA1253680 A CA 1253680A CA 000568264 A CA000568264 A CA 000568264A CA 568264 A CA568264 A CA 568264A CA 1253680 A CA1253680 A CA 1253680A
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- cement
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- cement slurry
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- retarder
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Abstract
ABSTRACT
There is described a method of cementing a subterra-nean zone penetrated by a well bore by providing a set retarded aqueous hydraulic cement slurry; admixing with the cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of: a triethanolamine titanium chelate represented by one of the formulae:
wherein R is independently an alkyl or aryl group,
There is described a method of cementing a subterra-nean zone penetrated by a well bore by providing a set retarded aqueous hydraulic cement slurry; admixing with the cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of: a triethanolamine titanium chelate represented by one of the formulae:
wherein R is independently an alkyl or aryl group,
Description
~S3~130 This application is a division of application No. 494,611 fi]ed November 5, 1985.
ackground o the Invent on 1. ~ield of the Invention This invention relates generally to set retarded cement compositions and methods of cementing across zones in wells, and more particularly, but not by way oE limitation, to set retarded cement compositions having enhanced compressive strength development after placement and methods of cementing across zones in wells using such compositions.
ackground o the Invent on 1. ~ield of the Invention This invention relates generally to set retarded cement compositions and methods of cementing across zones in wells, and more particularly, but not by way oE limitation, to set retarded cement compositions having enhanced compressive strength development after placement and methods of cementing across zones in wells using such compositions.
2. Description of the Prior Art In cementing operations carried out in oil, gas and water wells, a hydraulic cement is normally mixed with suf-ficient ~ater to form a pumpable slurry and the slurry is pumped across a subterranean zone or zones to be cemented by way of the wellbore penetrating such zone. After placement across the zone or zones, the cement slurry sets into a hard mass.
, . ~
While cement compositions are utilized in carrying out a variety of operations in wells to. accomplish a variety of purposes, cement composltions sre mos~ commcnly used in pri-.
. .
mary cementin~ whereby casing and/or liners are bondedwithin the wellbore to the formations penetrated thereby.
Cementing is accomplished by introducing a cement com-position into the annular space between the casing or liner and the wellbore, generally by pumping ~he cement com-positi~n downwardly within the casing or liner to the bottom thereof and then upwardly into the annulus, and then allowing the cement composition to set into a hard mass therein.
One or more of the Eormations or zones adjacent the cemented annulus can contain fluids under pressure which enter and flow through the cement-containing annulus when the cementing procedure carried out therein is faulty or inadequate. The most common problem of this nature is the flow or migration of gas in the cemented annulus. Such gas can flow to the surface, create communication between pro-ducing or other subterranean formations or zones and can, when in high enough volume, create blowouts during the cementing operation between when the cement composition is placed and before the cement composition has set into a hard mass. Minor interzonal gas flow problems can lower produc-tion. When the magnitude of leakage requires remedial action, expensive secondary cementing procedures must be carried out.
The occurrence of annular gas Elow in a cemented casing-wellbore annulus is believed to relate to the inability of .
;~ .
6~3~
the cement slurry to transmit hydrostatic pressure during the transition of the slurry from a true fluid to a hard, set mass. During this transition phase, initial hydration has begun and the slurry starts to develop static gel strength. Although the system has no compressive strength at this point, the cement column becomes partially self-supporting, This is a very critical period as far as poten-tial gas entry into the cement column i5 concerned. That is, although the original hydrostatic pressure is trapped within the gelled cement matrix, any volume reductions oE
; the aqueous phase at this point result in rapid decreases in the hydrostatic pressure due to the low compressibility of the fluid phase. Such volume reductions usually occur due to the ongoing hydration reactions and due to the loss of part of the Eluid phase to the formation (fluid loss). In this situation, it is possible for the pre~sure within the cement matrix to fall below the gas entry limit and for gas migration to occur.
Static gel stre~gth is the development of some internal rigidity in the matrix of the cement that will resist a force placed upon it. The development of static gel strength will start to occur immediately after pumping has ; stopped and will continue to increase until the cement is set, At some time before actual set, the cement will deve-lop a static gel strength high enough to prevent a fluid ,~
.
~ ~3-~ S3~
Lrom moving through it. Tests have indicated tha~ a gel strength of 500 pounds per 100 s~uare feet is suEficient to prevent any movement, although at certain conditions such gel strength can be considerably lower. When the cement has developed a static gel strength high enough to prevent for-mation fluids from moving through it, the cement is said to have completed its transition phase.
Volume reduction in the cement column can occur as a result of fluids lost from the cement slurry to the for-matlon. Even when fluid loss is very low, small amounts of fluid are still lost from the slurry which can result in a pressure drop in the cement column during the transition phase thereof. Additionally, as the cement in the cement slurry hydrates, a volume reduction caused ~y such hydration resulte. Hydration volumQ reduction can ultimately be as high as three percent. Where the static gel strength deve-lopment is slow and the volume reduction due to hydration and fluid loss are appreciable, the hydrostatic pressure exerted by the cement column on adjacent formations can drop below the pressure of formatlon fluids thereby allowing the fluids to enter the ~ement~filled annulu~. If the gel stren~th o~ the cement slurry is not high enough to prevent urther movement of formation fluids, a fingering or migra-tion phenomena will occur and annuIar gas leakage and~or Interzonal communicati~n w~ll ultimately result. Nowever, ~ .
~ .
~' ;3~
where the gel strength is high enough, the flow of formation fluids through the cement column is prevented.
Traditionally, the petroleum industry has attempted to prevent annulus formation fluid flow by increasing the cement slurry densityl improving mud displacement, controlling mud-cement slurry compatibility, using fluid loss control additives, causing the cement slurry to expand after setting, and multiple stage cementing. Although these techniques are helpful and have shown some measure of suc-cess, none have completely solved the problems. New tech-niques using cement slurries containing gas whereby the cement slurries are compressible have attained a much greater degree of success. Such techniques are the subject matter of U.S. Patents Nos. 4,304,298 and 4,340,427.
Another problem often encountered in cementing relates to the cement slurry developing ~ompressive strength at a 510w rate and/or the compressive strength development of the in-place cement column not being uniform. With the drilling of wells for the production of hydrocarbons to increased depths during recent years, extended cementing times are required to mix cement compositions and pump them into the annular space in the wells. In addition, at the greater depths, elevated temperatures are encountered which acce-lerate the normal setting rates of cement compositions to the point where the pumping times, i.e., the mixing and pla-;~ , , .
~ .
~Z5~6~
cement times, exceed the pumpable times of the cement com-positions, makiny it difficult or impossible to place the cement compositions at the desired locations in the wells.
In order to increase the pumpable times of cement com-positions, various set retarding additives have been uti-lized in cement compositions. While such additives successfully extend the pumpable times between mixing and the setting of cement compositions, they are temperature sensitive, i.e., the higher the temperature of the cement slurry, the greater the quantity of set retarder additive required. In cementing operations, especially when a long liner is involved, the static temperature of the cement column at the top thereof after placement can be con-siderably lower than the static temperature of the column at the bottom of the annulus, i.e., at the bottom hole static temperature ~HST). In some cementing applications, the static temperature of the cement column at the top can be as much as 40~F cooler than the BHST. In these applications, tbe cement slurrie~ must contain set retarders in quantities to achieve required pumpable times at the highest tem-perature to which the cement slurry is heated, and con-sequently, after placement the cooler slurry at the top of the cement column can take an excessive time to set and to develop compressive strength whereby the continuation of well operations is delayed.
~ .
~ -6-,~:
3L~53~30 By the present invention, set retarded cement com-positions for cementing àcross zones in wells are provided which have enhanced gel streng-th and compressive strength development after placement in the annulus. That is, the cement compositions develop high gel strength in a short period of time after placement followed by rapid compressive strength development. The rapid development of high gel strength in a short time span prevents fluid invasion into the annulus containing the cement composition even though the hydrostatic pressure of the cement column may all below the pressure of formatlon fluids during the transition of the slurry to a solid mass. Further, the enhanced and uni-form compressive strength development o the cement column in spite of a temperature differential over the length of the column shortens the down time required as a result of carrying out the cementing pxocedure.
Summary of the Invention A set retarded cement composition for cementing across a zone or zones in a well having enhanced compressive strength development a~ter placement in the annulus is provided. The composition is comprised of hydraulic cement, sufficient water to form a pumpable slurry which will set into a hard mass, one or more set retarders present in the slurry in a . . .
quantity sufficient to retard the set of the slurry until _7_ . .
:~S3~
after the slurry is placed in the annulus, and a delayed retarder neutralizer present in the slurry in a quantity suffi-cient to neutralize the one or more retarders and enhance the compressive strength development of the slurry after placement.
The de]ayed retarder neutralizer is comprised of one or more alkanolamine titanium chelates which hydrolize in the cement slurry to bring abou-t the delayed release of alkanolamines therein which in turn neutralize the retarding effect of the one or more set retarders therein. The cemen-t composition can also include one or more titanium crosslinkable materials which provide -thixotropic properties and gel strength develop-ment when crosslinked by titanium released from the alkano]-amine titanium chelates to the composition.
The invention also provides a method of cementing a subterranean zone penetrated by a well bore by providing a set retarded aqueous hydrau]ic cement slurry; admixing with -the cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consis-ting of: a triethanolamine titanium chelate represented by one of the formulae:
.~ , ~ ....................................... .
o :~ (HOCH2CH2)2 - N - C~2C~2 - RO \ ~ ¦
O - Ti - -O
¦ ~ OR
CH2CH2- N~ -(CH2CH20H)2 .
wherein ~ i9 independently an alkyl or aryl gro~p, (HCEl2c~l2)2 - N CH2CH2 O - Ti~ -o CH2CH2~ N -(CH2CH20H)2 '~
wherein Rl is independen-tly OC3H7, OH o~ a halogen atom, and partially polymerized chelates produced from the -triethanol-amine chelates, and placing -the cement slurry across the zone or zones by way of the well bore and allowing the cement slurry . to set into a hard mass therein having enhanced compressive .~ strength.
~` While a principal ob,ect o~ the cement compositions . . and methods of this invention is to combat the problems men-: tioned above encountered in cementing operations carried out ;
in wells, it is to be understood that the compositions and ~ methods can be utilized in a variety of secondary and other `~ well cementing operations.
, .
_g_ :
" ~s3~o ; Description of Preferred Embodiments The cement compositions o the present invention are comprised of pumpable aqueous hydraulic ceme~t slurries con-~; taining various components which, after placement in an ; annulus to be cemented, set into hard masses having required compressive strengths. While various hydraulic cements can be utilized in forming the slurries, Portland cement is pre-~ferably utilized and can be, for example, one or more of the various types identiied as ~PI Classes A-H and J cements.
These cements are identiEied and defined in ~PI Specification for Materials and ~estinq for Well Cements, API Spec. 10, Second Edition, June 15, 1984, of the American ~etroleum Institute.
The thickening and initial set times of cement com-positions are strongly dependent upon temperature and ` pressure. To obtain optimum results in oil, gas and water well applications, a variety of additives are often included in the cement compositions to vary the cement slurry den-~. .~ . .
sity, increase or decrease strength, accelerate or retard ~` thickening time, control ~luid loss, reduce slurry visco-sity, increase resistance to corrosive fluids, etc.
Essentially, a cement meeting the specifications of the American Petroleum Institute is mixed with water and other additives to provide a cement slurry appropriate for the ' conditions existing in each individual well to be cemented.
~ ' ~Z5~8~
In accordance with the present invention, a set retarded cement composition for cementing across a zone or zones in a well having enhanced and uniform compressive strength deve- -lopment after placement in the annulus is provided. The composition is comprised of hydraulic cement, sufficient water to form a pumpable slurry which will set into a hard mass, one or more set retarders and a delayed retarder neutralizer.
The set retarders which can be utilized in the com-positions of this invention are those which when present in the compositions in relatively small quantities retard the ~etting of the compositions, i.e.' increase the time period between mixing and setting whereby required p-lmping times can be achieved. The particular duration of set retardation brought about by the re-tarders is dependent upon a variety of factors including the temperature of the cement com-positions containing the retarders, the quantities of retar-ders utilized therein, the reactivity of the retarders with other components in the cement compositions ! etc. Examples of parkicularly suitable such set retarders are salts of lignosulfonates, organic acids and their salts, mixtures of these compoundsl and combinations of these compounds in admixture with one or more water soluble borates. Of -these, calcium lignosulfonate and potassium pentaborate tetra-hydrate in a 1:1 ratio by weight is preferred. A11 of the ~536~ , above-mentioned set retarders, and possibly all set retar-ders effective in cement compositions of -the type herein contemplated, are neutralized, i.e., the set retardation effect thereof terminated, when contacted or reacted with amines such as triethanolamine.
As mentioned above, the cement compositions of the pre-sent invention include, in addition to the one or more set retarders described above, a delayed retarder neutralizer present in the composition in a quantity sufficient to neutralize the one or more set retarders and thereby bring about the enhanced and uniform compressive strength develop-ment of the composition after the placement thereof in an annulus to be cemented. Such delayed retarder neutralizer is comprised of an alkanolamine titanium chelate or a mix-ture oP such chelates which when added to a hydraulic cement slurry, slowly hydrolize to liberate amines in the slurry.
Particularly suitable such chelates include triethanolamine titanium chelate represe~ted by the formula:
~HocH2cH2 ) 2-N CH2CH2 H7C30 `
0 -~ - Ti --- - 0 j ~ OC3H7 CH2CH2 - N - (cH2cH2oH~2 and modification: of surh che e which include rep1acement .
: ;:
o of the -C3H7 qroup with various other alkyl or aryl groups or replacement of the -OC3H7 groups with hydroxide or halo-gen atoms, and partially polymerized versions of these che-lates. Other ligands use~ul .in this class which may replace one or both of the triethanolamine ligands include ~R1)2N-R2-H where Rl i~ hydrogen, alkyl, and/or hydroxyalkyl and R2 is ethylenel trimethylene, or isopropy-lene (-C(CH3)2-)r R4(R5)N-R3-N(R6)(R7) where R3 is ethylene, trimethylene, or isopropylene ~-C(CH3)2-) and R4, Rs, R6, and R7 are individually hydrogen, alkyl, hydroxyalkyl, and/or aminoalkyl gro~ps with the limitation that each possible molecule contains at least one hydroxyalkyl group, and various other alXanolamines. The modified complexes can contain in the range of from one to four alkanolamine ligands per titanium atom.
The preEerred titanium chelate represented by the above ~- formula is prepared by the reaction of titanium isopropoxide with two moles of txiethanolamine to yield isopropoxytita-nium triethanolamine chelate plus two moles of isopropyl alcohol. The product is a liquid containing about 8.3 titanium.
; A preferred class of solid tita~ium chelates are described in U.S. Patent No. 2,935,522 issued May 3, 1960.
These chelates have the following general formula:
~ .
- `~
j O Rl\
RO Ti - o - Rl - N
`' O -- Rl wherein R i9 isopropyl ~-C3H7) and Rl is ethylene or isopro-pylene. A partic~larly preferred chelate of this type for use in accordance with this invention is a chelate of the above Eormula wherein R is isopropyl and Rl is ethylene, i.e., isopropoxytitanium triethanolamine chelate. This che-- late is a white free-flowing solid which can be readily dry-blended with a hydraulic cement.
-Modifications of the above chelate include products con-taining two kriethanolamine groups represented by the struc-tural formula:
~ / \ / Rl\
N \ Rl Ti - o - Rl N
Rl - O H - R
where Rl is ethylene or isopropylene;
and dimers with a structure represented by the ollowing:
- O \ Rl \
N ~ Rl - Ti - O - Ti o ~ Rl - N
Rl -- O ' Rl where Rl is ethylene or isopropylene.
As mentioned above, the particular quantity of the one or more set retarders utilized in the cement compositions depends upon various factors including the time required and ' , ~L~53~:;80 ,~ , the temperature to which the cement composition will be heated during and after placement. Generally, the retarder or retarders are included in the cement compositions in amounts in the range o~ from about 0.1~ to about 5.0% by weight of dry cement utilized therein. When the preferred retarder comprised o~ calcium liynosul~onate and potassium pentaborate tetrahydrate in a 1:1 ratio by weight is uti-lized, it is included in the cement compositions in amounts in the range of from about 0.5% to about 3.0% by weight of ~ . :
dry cement utilized.
The amounts of delayed retarder neutralizer or mixtures of neutralizers utilized in the cement compositions will vary with the amounts of retarder or retarders present, the amounts of crosslinkable material present, if any, and to some degree, the temperatures to which the cement com-positions will be heated during and after placement. The general amount of retarder neutralizer used may vary as much as from 0.05% to about 1.5% by weight o~ dry cement used.
The more usual and preferred range is from about 0.1~ to about 0.5% by weight of dry cement. When combined with a cement slurry, the titanium chelate neutralizers slowly hydrolyze to release amines which in turn function in the slurry to neutralize the efects of the retarders. Thus, once the chelates hydrolyze and produce amines, the cement slurry will rapidly set and compressive strength will rapidly be developed.
. . ~ .
_ 5_ 1~25~36~ , A thixotropic set retarded cement composition oE this invention having enhanced gel strength and compressive strength development after placement in the zone to bs cemented is comprised of hydraulic cement, water, one or more set retarders, a cross-linkable material, and a crosslinking agent which also neutral-izes the inEluence of retarders, i.e., an alkanolamine titanium chelate or mixture oE chelates.
The crosslinkable material must be capable of being cross-linked by titanium as well as being water soluble and relatively non-reactive with other components in the cement compositions. PreEerably, the material is selected from the group consisting oE cellulose ethers exemplified by hydroxyalkylcellulose, carboxyalkylcellulose or car-boxyalkylhydroxyalkylcellulose; polyvinyl alcohol; homopoly-mer~, copolymers and terpolymers of AMPS
~2-acrylamido-2-methylpropane sulfonic acid), sodium vinylsulfonate, acrylamide, N,N-dime~hylacrylamide, acrylic acid and mixtures thereo. Most preferably, the crosslinkable material is selected from the group consisting of carboxymethylhydroxyethylcellulose, hydroxyethylcellu-lose, a copolymer of 2-acrylamido2-methylpropane sulfonic acid and N~N-dimethylacrylamide and mixtures of these com-pounds.
The crosslinkable material is generally included in the thixotropic cement compositions of this invention in an .:
, . ~
While cement compositions are utilized in carrying out a variety of operations in wells to. accomplish a variety of purposes, cement composltions sre mos~ commcnly used in pri-.
. .
mary cementin~ whereby casing and/or liners are bondedwithin the wellbore to the formations penetrated thereby.
Cementing is accomplished by introducing a cement com-position into the annular space between the casing or liner and the wellbore, generally by pumping ~he cement com-positi~n downwardly within the casing or liner to the bottom thereof and then upwardly into the annulus, and then allowing the cement composition to set into a hard mass therein.
One or more of the Eormations or zones adjacent the cemented annulus can contain fluids under pressure which enter and flow through the cement-containing annulus when the cementing procedure carried out therein is faulty or inadequate. The most common problem of this nature is the flow or migration of gas in the cemented annulus. Such gas can flow to the surface, create communication between pro-ducing or other subterranean formations or zones and can, when in high enough volume, create blowouts during the cementing operation between when the cement composition is placed and before the cement composition has set into a hard mass. Minor interzonal gas flow problems can lower produc-tion. When the magnitude of leakage requires remedial action, expensive secondary cementing procedures must be carried out.
The occurrence of annular gas Elow in a cemented casing-wellbore annulus is believed to relate to the inability of .
;~ .
6~3~
the cement slurry to transmit hydrostatic pressure during the transition of the slurry from a true fluid to a hard, set mass. During this transition phase, initial hydration has begun and the slurry starts to develop static gel strength. Although the system has no compressive strength at this point, the cement column becomes partially self-supporting, This is a very critical period as far as poten-tial gas entry into the cement column i5 concerned. That is, although the original hydrostatic pressure is trapped within the gelled cement matrix, any volume reductions oE
; the aqueous phase at this point result in rapid decreases in the hydrostatic pressure due to the low compressibility of the fluid phase. Such volume reductions usually occur due to the ongoing hydration reactions and due to the loss of part of the Eluid phase to the formation (fluid loss). In this situation, it is possible for the pre~sure within the cement matrix to fall below the gas entry limit and for gas migration to occur.
Static gel stre~gth is the development of some internal rigidity in the matrix of the cement that will resist a force placed upon it. The development of static gel strength will start to occur immediately after pumping has ; stopped and will continue to increase until the cement is set, At some time before actual set, the cement will deve-lop a static gel strength high enough to prevent a fluid ,~
.
~ ~3-~ S3~
Lrom moving through it. Tests have indicated tha~ a gel strength of 500 pounds per 100 s~uare feet is suEficient to prevent any movement, although at certain conditions such gel strength can be considerably lower. When the cement has developed a static gel strength high enough to prevent for-mation fluids from moving through it, the cement is said to have completed its transition phase.
Volume reduction in the cement column can occur as a result of fluids lost from the cement slurry to the for-matlon. Even when fluid loss is very low, small amounts of fluid are still lost from the slurry which can result in a pressure drop in the cement column during the transition phase thereof. Additionally, as the cement in the cement slurry hydrates, a volume reduction caused ~y such hydration resulte. Hydration volumQ reduction can ultimately be as high as three percent. Where the static gel strength deve-lopment is slow and the volume reduction due to hydration and fluid loss are appreciable, the hydrostatic pressure exerted by the cement column on adjacent formations can drop below the pressure of formatlon fluids thereby allowing the fluids to enter the ~ement~filled annulu~. If the gel stren~th o~ the cement slurry is not high enough to prevent urther movement of formation fluids, a fingering or migra-tion phenomena will occur and annuIar gas leakage and~or Interzonal communicati~n w~ll ultimately result. Nowever, ~ .
~ .
~' ;3~
where the gel strength is high enough, the flow of formation fluids through the cement column is prevented.
Traditionally, the petroleum industry has attempted to prevent annulus formation fluid flow by increasing the cement slurry densityl improving mud displacement, controlling mud-cement slurry compatibility, using fluid loss control additives, causing the cement slurry to expand after setting, and multiple stage cementing. Although these techniques are helpful and have shown some measure of suc-cess, none have completely solved the problems. New tech-niques using cement slurries containing gas whereby the cement slurries are compressible have attained a much greater degree of success. Such techniques are the subject matter of U.S. Patents Nos. 4,304,298 and 4,340,427.
Another problem often encountered in cementing relates to the cement slurry developing ~ompressive strength at a 510w rate and/or the compressive strength development of the in-place cement column not being uniform. With the drilling of wells for the production of hydrocarbons to increased depths during recent years, extended cementing times are required to mix cement compositions and pump them into the annular space in the wells. In addition, at the greater depths, elevated temperatures are encountered which acce-lerate the normal setting rates of cement compositions to the point where the pumping times, i.e., the mixing and pla-;~ , , .
~ .
~Z5~6~
cement times, exceed the pumpable times of the cement com-positions, makiny it difficult or impossible to place the cement compositions at the desired locations in the wells.
In order to increase the pumpable times of cement com-positions, various set retarding additives have been uti-lized in cement compositions. While such additives successfully extend the pumpable times between mixing and the setting of cement compositions, they are temperature sensitive, i.e., the higher the temperature of the cement slurry, the greater the quantity of set retarder additive required. In cementing operations, especially when a long liner is involved, the static temperature of the cement column at the top thereof after placement can be con-siderably lower than the static temperature of the column at the bottom of the annulus, i.e., at the bottom hole static temperature ~HST). In some cementing applications, the static temperature of the cement column at the top can be as much as 40~F cooler than the BHST. In these applications, tbe cement slurrie~ must contain set retarders in quantities to achieve required pumpable times at the highest tem-perature to which the cement slurry is heated, and con-sequently, after placement the cooler slurry at the top of the cement column can take an excessive time to set and to develop compressive strength whereby the continuation of well operations is delayed.
~ .
~ -6-,~:
3L~53~30 By the present invention, set retarded cement com-positions for cementing àcross zones in wells are provided which have enhanced gel streng-th and compressive strength development after placement in the annulus. That is, the cement compositions develop high gel strength in a short period of time after placement followed by rapid compressive strength development. The rapid development of high gel strength in a short time span prevents fluid invasion into the annulus containing the cement composition even though the hydrostatic pressure of the cement column may all below the pressure of formatlon fluids during the transition of the slurry to a solid mass. Further, the enhanced and uni-form compressive strength development o the cement column in spite of a temperature differential over the length of the column shortens the down time required as a result of carrying out the cementing pxocedure.
Summary of the Invention A set retarded cement composition for cementing across a zone or zones in a well having enhanced compressive strength development a~ter placement in the annulus is provided. The composition is comprised of hydraulic cement, sufficient water to form a pumpable slurry which will set into a hard mass, one or more set retarders present in the slurry in a . . .
quantity sufficient to retard the set of the slurry until _7_ . .
:~S3~
after the slurry is placed in the annulus, and a delayed retarder neutralizer present in the slurry in a quantity suffi-cient to neutralize the one or more retarders and enhance the compressive strength development of the slurry after placement.
The de]ayed retarder neutralizer is comprised of one or more alkanolamine titanium chelates which hydrolize in the cement slurry to bring abou-t the delayed release of alkanolamines therein which in turn neutralize the retarding effect of the one or more set retarders therein. The cemen-t composition can also include one or more titanium crosslinkable materials which provide -thixotropic properties and gel strength develop-ment when crosslinked by titanium released from the alkano]-amine titanium chelates to the composition.
The invention also provides a method of cementing a subterranean zone penetrated by a well bore by providing a set retarded aqueous hydrau]ic cement slurry; admixing with -the cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consis-ting of: a triethanolamine titanium chelate represented by one of the formulae:
.~ , ~ ....................................... .
o :~ (HOCH2CH2)2 - N - C~2C~2 - RO \ ~ ¦
O - Ti - -O
¦ ~ OR
CH2CH2- N~ -(CH2CH20H)2 .
wherein ~ i9 independently an alkyl or aryl gro~p, (HCEl2c~l2)2 - N CH2CH2 O - Ti~ -o CH2CH2~ N -(CH2CH20H)2 '~
wherein Rl is independen-tly OC3H7, OH o~ a halogen atom, and partially polymerized chelates produced from the -triethanol-amine chelates, and placing -the cement slurry across the zone or zones by way of the well bore and allowing the cement slurry . to set into a hard mass therein having enhanced compressive .~ strength.
~` While a principal ob,ect o~ the cement compositions . . and methods of this invention is to combat the problems men-: tioned above encountered in cementing operations carried out ;
in wells, it is to be understood that the compositions and ~ methods can be utilized in a variety of secondary and other `~ well cementing operations.
, .
_g_ :
" ~s3~o ; Description of Preferred Embodiments The cement compositions o the present invention are comprised of pumpable aqueous hydraulic ceme~t slurries con-~; taining various components which, after placement in an ; annulus to be cemented, set into hard masses having required compressive strengths. While various hydraulic cements can be utilized in forming the slurries, Portland cement is pre-~ferably utilized and can be, for example, one or more of the various types identiied as ~PI Classes A-H and J cements.
These cements are identiEied and defined in ~PI Specification for Materials and ~estinq for Well Cements, API Spec. 10, Second Edition, June 15, 1984, of the American ~etroleum Institute.
The thickening and initial set times of cement com-positions are strongly dependent upon temperature and ` pressure. To obtain optimum results in oil, gas and water well applications, a variety of additives are often included in the cement compositions to vary the cement slurry den-~. .~ . .
sity, increase or decrease strength, accelerate or retard ~` thickening time, control ~luid loss, reduce slurry visco-sity, increase resistance to corrosive fluids, etc.
Essentially, a cement meeting the specifications of the American Petroleum Institute is mixed with water and other additives to provide a cement slurry appropriate for the ' conditions existing in each individual well to be cemented.
~ ' ~Z5~8~
In accordance with the present invention, a set retarded cement composition for cementing across a zone or zones in a well having enhanced and uniform compressive strength deve- -lopment after placement in the annulus is provided. The composition is comprised of hydraulic cement, sufficient water to form a pumpable slurry which will set into a hard mass, one or more set retarders and a delayed retarder neutralizer.
The set retarders which can be utilized in the com-positions of this invention are those which when present in the compositions in relatively small quantities retard the ~etting of the compositions, i.e.' increase the time period between mixing and setting whereby required p-lmping times can be achieved. The particular duration of set retardation brought about by the re-tarders is dependent upon a variety of factors including the temperature of the cement com-positions containing the retarders, the quantities of retar-ders utilized therein, the reactivity of the retarders with other components in the cement compositions ! etc. Examples of parkicularly suitable such set retarders are salts of lignosulfonates, organic acids and their salts, mixtures of these compoundsl and combinations of these compounds in admixture with one or more water soluble borates. Of -these, calcium lignosulfonate and potassium pentaborate tetra-hydrate in a 1:1 ratio by weight is preferred. A11 of the ~536~ , above-mentioned set retarders, and possibly all set retar-ders effective in cement compositions of -the type herein contemplated, are neutralized, i.e., the set retardation effect thereof terminated, when contacted or reacted with amines such as triethanolamine.
As mentioned above, the cement compositions of the pre-sent invention include, in addition to the one or more set retarders described above, a delayed retarder neutralizer present in the composition in a quantity sufficient to neutralize the one or more set retarders and thereby bring about the enhanced and uniform compressive strength develop-ment of the composition after the placement thereof in an annulus to be cemented. Such delayed retarder neutralizer is comprised of an alkanolamine titanium chelate or a mix-ture oP such chelates which when added to a hydraulic cement slurry, slowly hydrolize to liberate amines in the slurry.
Particularly suitable such chelates include triethanolamine titanium chelate represe~ted by the formula:
~HocH2cH2 ) 2-N CH2CH2 H7C30 `
0 -~ - Ti --- - 0 j ~ OC3H7 CH2CH2 - N - (cH2cH2oH~2 and modification: of surh che e which include rep1acement .
: ;:
o of the -C3H7 qroup with various other alkyl or aryl groups or replacement of the -OC3H7 groups with hydroxide or halo-gen atoms, and partially polymerized versions of these che-lates. Other ligands use~ul .in this class which may replace one or both of the triethanolamine ligands include ~R1)2N-R2-H where Rl i~ hydrogen, alkyl, and/or hydroxyalkyl and R2 is ethylenel trimethylene, or isopropy-lene (-C(CH3)2-)r R4(R5)N-R3-N(R6)(R7) where R3 is ethylene, trimethylene, or isopropylene ~-C(CH3)2-) and R4, Rs, R6, and R7 are individually hydrogen, alkyl, hydroxyalkyl, and/or aminoalkyl gro~ps with the limitation that each possible molecule contains at least one hydroxyalkyl group, and various other alXanolamines. The modified complexes can contain in the range of from one to four alkanolamine ligands per titanium atom.
The preEerred titanium chelate represented by the above ~- formula is prepared by the reaction of titanium isopropoxide with two moles of txiethanolamine to yield isopropoxytita-nium triethanolamine chelate plus two moles of isopropyl alcohol. The product is a liquid containing about 8.3 titanium.
; A preferred class of solid tita~ium chelates are described in U.S. Patent No. 2,935,522 issued May 3, 1960.
These chelates have the following general formula:
~ .
- `~
j O Rl\
RO Ti - o - Rl - N
`' O -- Rl wherein R i9 isopropyl ~-C3H7) and Rl is ethylene or isopro-pylene. A partic~larly preferred chelate of this type for use in accordance with this invention is a chelate of the above Eormula wherein R is isopropyl and Rl is ethylene, i.e., isopropoxytitanium triethanolamine chelate. This che-- late is a white free-flowing solid which can be readily dry-blended with a hydraulic cement.
-Modifications of the above chelate include products con-taining two kriethanolamine groups represented by the struc-tural formula:
~ / \ / Rl\
N \ Rl Ti - o - Rl N
Rl - O H - R
where Rl is ethylene or isopropylene;
and dimers with a structure represented by the ollowing:
- O \ Rl \
N ~ Rl - Ti - O - Ti o ~ Rl - N
Rl -- O ' Rl where Rl is ethylene or isopropylene.
As mentioned above, the particular quantity of the one or more set retarders utilized in the cement compositions depends upon various factors including the time required and ' , ~L~53~:;80 ,~ , the temperature to which the cement composition will be heated during and after placement. Generally, the retarder or retarders are included in the cement compositions in amounts in the range o~ from about 0.1~ to about 5.0% by weight of dry cement utilized therein. When the preferred retarder comprised o~ calcium liynosul~onate and potassium pentaborate tetrahydrate in a 1:1 ratio by weight is uti-lized, it is included in the cement compositions in amounts in the range of from about 0.5% to about 3.0% by weight of ~ . :
dry cement utilized.
The amounts of delayed retarder neutralizer or mixtures of neutralizers utilized in the cement compositions will vary with the amounts of retarder or retarders present, the amounts of crosslinkable material present, if any, and to some degree, the temperatures to which the cement com-positions will be heated during and after placement. The general amount of retarder neutralizer used may vary as much as from 0.05% to about 1.5% by weight o~ dry cement used.
The more usual and preferred range is from about 0.1~ to about 0.5% by weight of dry cement. When combined with a cement slurry, the titanium chelate neutralizers slowly hydrolyze to release amines which in turn function in the slurry to neutralize the efects of the retarders. Thus, once the chelates hydrolyze and produce amines, the cement slurry will rapidly set and compressive strength will rapidly be developed.
. . ~ .
_ 5_ 1~25~36~ , A thixotropic set retarded cement composition oE this invention having enhanced gel strength and compressive strength development after placement in the zone to bs cemented is comprised of hydraulic cement, water, one or more set retarders, a cross-linkable material, and a crosslinking agent which also neutral-izes the inEluence of retarders, i.e., an alkanolamine titanium chelate or mixture oE chelates.
The crosslinkable material must be capable of being cross-linked by titanium as well as being water soluble and relatively non-reactive with other components in the cement compositions. PreEerably, the material is selected from the group consisting oE cellulose ethers exemplified by hydroxyalkylcellulose, carboxyalkylcellulose or car-boxyalkylhydroxyalkylcellulose; polyvinyl alcohol; homopoly-mer~, copolymers and terpolymers of AMPS
~2-acrylamido-2-methylpropane sulfonic acid), sodium vinylsulfonate, acrylamide, N,N-dime~hylacrylamide, acrylic acid and mixtures thereo. Most preferably, the crosslinkable material is selected from the group consisting of carboxymethylhydroxyethylcellulose, hydroxyethylcellu-lose, a copolymer of 2-acrylamido2-methylpropane sulfonic acid and N~N-dimethylacrylamide and mixtures of these com-pounds.
The crosslinkable material is generally included in the thixotropic cement compositions of this invention in an .:
3~
amount in tha range of from about 0.1~ to about 2.0~ by weight of dry cement utilized. A more preferred range of crosslinkable material is from about 0.2~ to about 0.6% by weight o dry cement.
As will be understood, in the thixotropic cement compositions, as the crosslinking-retarder neutralizing agent slowly hydrolyzes, the released titanium crosslinks the crosslinkable material in the composition which brings abou-t the rapid development of gel strength during the tran-sition phase of the cement composition after placement.
Simultaneously, the alkanolamines released react with or otherwise function to neutralize the retarding effect of the set retarders which in turn causes the cement composition to set and rapidly develop compressive strength after place-ment The quantities of the one or more set re-tarders and the alkanolamine titanium chelate or chelates utilized in the thixotropic set retarded cement compositions are essentially the same as set forth above for the non-thixotropic set retarded cement compositions.
A preferred set retarded cement composition of this invention is comprised of hydraulic cement, sufficient water to form a pumpable slurry which will set into a hard mass, one or more sat retarders selected from the group consisting o salts of lignosulfonates, organic acids and their salts, ~ ~ .
:' , :`
~S36~3~
.: ` --` .
~ixtures of the foregoing compounds and one or more of the foregoing compounds in admixture with one or more water soluble borates present in -the composition in an amount in ; the range of from about 0.1~ to about 5.0% by weight of dry cement therein, and a delayed retarder neutralizer comprised of one or more of the titanium chelates described above pre-sent in the composition in an amount in the range of from about 0.05~ to about 1.5% by weight o~ dry cement.
The most preferred such cement composition includes a set retarder comprised oE calcium lignosulfonate and potassium pentaborate tetrahydrate in a l:l ratio by weight present in the composition in an amount in the range of from -about 0.5~ to about 1.5% by weight of dry cement, and isopropoxytitanium triethanolamine chelate present in the composition in an amount in the range of from about 0.1~ to about 0.5~ by weight of dry cement.
A preferred thixotropic set retarded cement composition o this invention is comprised of hydraulic cement, suf-~icient water to form a pumpable slurry which will set into a hard mass, a set retarder Eor delaying the set o~ the slurry selected from the group consisting of salts of ligno-: sulonates, organic acids and their salts, mixtures of the foregoing compounds and one or more of the foregoing com~
pounds in admixture with one or more water soluble borates present in the composition in an amount in the range of Erom .` ~ .
' ' :
, about 0.1% to about 5.0% by weight oE dry cement, a crosslinkable material Eor producing thixotropic properties and gel strength development in said composition when crosslinked with titanium selected from the group consisting of carboxy-methylhydroxyethylcellulose, hydroxyethylcellu-lose, a copolymer of 2-acrylamido-2-methylpropana sulfonic acid and ~N-dimethylacrylamide and mixtures thereof present in the composition in an amount in the range of from about 0.1% to about 2.0~ by weight of dry cement, and the titanium chelate or mixture of chelates described above present in the composition in an amount in the range of from about 0.05~ to about 1.5% by weight oE dry cement therein.
The most preEerred thixotropic, set retarded cement composition includes a set retarder comprised oE calcium lignosulfonate and potassium pentaborate tetrahydrate in a l:l ratio by weight present in the composition in an amount in the range of from about 0.5% to about 3.0% by weight of dry cement, a crosqlinkable material comprised ~f carboxymethylhydroxyethylcellulose present in the com-position in an amount in the range of from about 0.2% to about 0.6% by weight of dry cement and isopropoxytitanium triethanolamine chelate present in the composition in an amount in the range of from about 0.l% to about 0.5% by weight of dry cement therein.
In carrying out the method of the present invention, a set retarded or thixotropic, set retarded cement composition 6~0 is formed including one or more retarders present in a quan-tity sufEicient to retard the set of the composition until after it is placed across the interval to be cemented. The delayed retarder neutralizer is included in the composition in a quantity sufficient to neutrali~e the retarder aEter placement of the composition whereby rapid gel stxength and compressive strength developmen-t take place. In the case of a thixotropic composition including crosslinkable material, the crosslinker-retarder neutralizer simultaneously cross-links the crosslinkable material and neutralizes the retarder bringing about the formation of high gel strength during the transition phase as well as the rapid and uniform development of compressive strength thereafter. The set retarded cement compositions are pumped across the interval to be cemented and then allowed to set into a hrd mass.
The pumping times of the compositions can be extended by the inclusion of retarders therein up to 12 hours at bottom hole circulating temperatures of up to 400F. As mentioned above, the in situ hydrolysis of the alkanolamine chelates is slow whereby the set retarders are not totally neutra-lized nor is the crosslinkable material completely crosslinked until after placement of the cement com-positions.
In order to facilitate a clear understanding of the methods and compositions of this invention, the following .
il2~ 30 :
Examples are given.
Example 1 A series oE tests are conducted to determine how effec-tive a variety of titanium chelates are in producing thixotropic behavior. The cement slurries tested are pre-pared by dry blending all the additives with the cement prior to addition to wa-ter~ If any liquid additives are used, the li~uid is added to the mixing water prior to adding cement. The cement slurry is placed in a static gel strength measuring device and a standard thixotropic test is conducted.
The static yel strength measuring apparatus consists of three major components, the chamber and lid, the magnetic drive assembly, and the cord pulling assembly.
The chamber is a heavy wall, high strength metal vessel equipped with strip heaters attached directly to the outside of the chamber. A thermocouple is inserted into the vessel to allow the temperature of the vessel to be controlled.
The lid of the chamber is equipped s~ -that the principal drive shaEt of the magnetic drive assembly can be inserted.
On the shaft a stirring paddle is fitted over one end of the shaft and secured with a shear pin. On the other end of the principal drive shaft the magnetic drive head is connected.
The magnetic drive head is then in turn connected by a belt , ~' ', .
, :
~.
3~2~3~8~
system to a variable speed magnetic drive power source and torque measuring device. A thermocouple is inserted through the top of the magnetic drive head and down the middle oE
the hollow principal drive shaft. The lid of the chamber is equipped with two ports. One port is connected to a pressure volume pump used to generate pressure and the other port is equipped with a quick opening safety valve. The bottom of the chamber is equipped with a quick opening valve and used to relieve the pressure and discharge the test slurry at the end of the test period. The cord pulling mechanism consists oE a cord pulling capstan or drum arrangement driven by a variable speed gear motor with the cord running through the pulley arrangement to a load cell and then to the top of the magnetic drive head.
To determine the gel strength development oE cement slurry under down hole conditions, this equipment was speci-fically designed for measuring static gel strength ater a stirring period that simulated slurry placement. The equip-ment is designed to operate at a max~mum tempeature of 400F
at 10,000 psi. The low friction magnetic drive allows the slurry to be stirred while monitoring consistency during the stirring time. A~ter simulating placement time, the motor is shut ofE and the cord pulling system is attached to the magnetic drive head. Static gel strength is determined by continuously measuring the torque required to rotate the :lZ~6~30 paddle at a very slow speed (O.5 to 2.0 per minu-te). At such speeds, a magnetic drive has very low friction and very accurate torque measurements can be made. Since the torque measuring system consists of a cord pulling capstan or drum arrangement driven by a variable speed gear motor, accurate continuous rotation and means for continuously rec~rding the torque are provided. The gel strength i5 then calculated from the torque measureme,nt and the vessel geometry. The slow movement of the paddle allows static gel strength to be measured but does not inhibit gel strength development.
Continuous static gel strength values can be measured up to a maximum of 1000 lbs/100 ft2.
The standard thixotropic test procedure is as follows:
1. stir the slurry wi-th the magnetic drive consistometer for one hour while increasing temperature and pressure Erom ambient conditions to bottom hole cir-culating temperature tsHCT~ and bottom hole pressure ; (BHP) according to schedule;
2. after one hour of stirring, set static for 15 minutes while continuall~ measuring static gel strength;
' 3. after a static period of 15 minutes, stir for 15 minutes while continually measuring consistency; and
amount in tha range of from about 0.1~ to about 2.0~ by weight of dry cement utilized. A more preferred range of crosslinkable material is from about 0.2~ to about 0.6% by weight o dry cement.
As will be understood, in the thixotropic cement compositions, as the crosslinking-retarder neutralizing agent slowly hydrolyzes, the released titanium crosslinks the crosslinkable material in the composition which brings abou-t the rapid development of gel strength during the tran-sition phase of the cement composition after placement.
Simultaneously, the alkanolamines released react with or otherwise function to neutralize the retarding effect of the set retarders which in turn causes the cement composition to set and rapidly develop compressive strength after place-ment The quantities of the one or more set re-tarders and the alkanolamine titanium chelate or chelates utilized in the thixotropic set retarded cement compositions are essentially the same as set forth above for the non-thixotropic set retarded cement compositions.
A preferred set retarded cement composition of this invention is comprised of hydraulic cement, sufficient water to form a pumpable slurry which will set into a hard mass, one or more sat retarders selected from the group consisting o salts of lignosulfonates, organic acids and their salts, ~ ~ .
:' , :`
~S36~3~
.: ` --` .
~ixtures of the foregoing compounds and one or more of the foregoing compounds in admixture with one or more water soluble borates present in -the composition in an amount in ; the range of from about 0.1~ to about 5.0% by weight of dry cement therein, and a delayed retarder neutralizer comprised of one or more of the titanium chelates described above pre-sent in the composition in an amount in the range of from about 0.05~ to about 1.5% by weight o~ dry cement.
The most preferred such cement composition includes a set retarder comprised oE calcium lignosulfonate and potassium pentaborate tetrahydrate in a l:l ratio by weight present in the composition in an amount in the range of from -about 0.5~ to about 1.5% by weight of dry cement, and isopropoxytitanium triethanolamine chelate present in the composition in an amount in the range of from about 0.1~ to about 0.5~ by weight of dry cement.
A preferred thixotropic set retarded cement composition o this invention is comprised of hydraulic cement, suf-~icient water to form a pumpable slurry which will set into a hard mass, a set retarder Eor delaying the set o~ the slurry selected from the group consisting of salts of ligno-: sulonates, organic acids and their salts, mixtures of the foregoing compounds and one or more of the foregoing com~
pounds in admixture with one or more water soluble borates present in the composition in an amount in the range of Erom .` ~ .
' ' :
, about 0.1% to about 5.0% by weight oE dry cement, a crosslinkable material Eor producing thixotropic properties and gel strength development in said composition when crosslinked with titanium selected from the group consisting of carboxy-methylhydroxyethylcellulose, hydroxyethylcellu-lose, a copolymer of 2-acrylamido-2-methylpropana sulfonic acid and ~N-dimethylacrylamide and mixtures thereof present in the composition in an amount in the range of from about 0.1% to about 2.0~ by weight of dry cement, and the titanium chelate or mixture of chelates described above present in the composition in an amount in the range of from about 0.05~ to about 1.5% by weight oE dry cement therein.
The most preEerred thixotropic, set retarded cement composition includes a set retarder comprised oE calcium lignosulfonate and potassium pentaborate tetrahydrate in a l:l ratio by weight present in the composition in an amount in the range of from about 0.5% to about 3.0% by weight of dry cement, a crosqlinkable material comprised ~f carboxymethylhydroxyethylcellulose present in the com-position in an amount in the range of from about 0.2% to about 0.6% by weight of dry cement and isopropoxytitanium triethanolamine chelate present in the composition in an amount in the range of from about 0.l% to about 0.5% by weight of dry cement therein.
In carrying out the method of the present invention, a set retarded or thixotropic, set retarded cement composition 6~0 is formed including one or more retarders present in a quan-tity sufEicient to retard the set of the composition until after it is placed across the interval to be cemented. The delayed retarder neutralizer is included in the composition in a quantity sufficient to neutrali~e the retarder aEter placement of the composition whereby rapid gel stxength and compressive strength developmen-t take place. In the case of a thixotropic composition including crosslinkable material, the crosslinker-retarder neutralizer simultaneously cross-links the crosslinkable material and neutralizes the retarder bringing about the formation of high gel strength during the transition phase as well as the rapid and uniform development of compressive strength thereafter. The set retarded cement compositions are pumped across the interval to be cemented and then allowed to set into a hrd mass.
The pumping times of the compositions can be extended by the inclusion of retarders therein up to 12 hours at bottom hole circulating temperatures of up to 400F. As mentioned above, the in situ hydrolysis of the alkanolamine chelates is slow whereby the set retarders are not totally neutra-lized nor is the crosslinkable material completely crosslinked until after placement of the cement com-positions.
In order to facilitate a clear understanding of the methods and compositions of this invention, the following .
il2~ 30 :
Examples are given.
Example 1 A series oE tests are conducted to determine how effec-tive a variety of titanium chelates are in producing thixotropic behavior. The cement slurries tested are pre-pared by dry blending all the additives with the cement prior to addition to wa-ter~ If any liquid additives are used, the li~uid is added to the mixing water prior to adding cement. The cement slurry is placed in a static gel strength measuring device and a standard thixotropic test is conducted.
The static yel strength measuring apparatus consists of three major components, the chamber and lid, the magnetic drive assembly, and the cord pulling assembly.
The chamber is a heavy wall, high strength metal vessel equipped with strip heaters attached directly to the outside of the chamber. A thermocouple is inserted into the vessel to allow the temperature of the vessel to be controlled.
The lid of the chamber is equipped s~ -that the principal drive shaEt of the magnetic drive assembly can be inserted.
On the shaft a stirring paddle is fitted over one end of the shaft and secured with a shear pin. On the other end of the principal drive shaft the magnetic drive head is connected.
The magnetic drive head is then in turn connected by a belt , ~' ', .
, :
~.
3~2~3~8~
system to a variable speed magnetic drive power source and torque measuring device. A thermocouple is inserted through the top of the magnetic drive head and down the middle oE
the hollow principal drive shaft. The lid of the chamber is equipped with two ports. One port is connected to a pressure volume pump used to generate pressure and the other port is equipped with a quick opening safety valve. The bottom of the chamber is equipped with a quick opening valve and used to relieve the pressure and discharge the test slurry at the end of the test period. The cord pulling mechanism consists oE a cord pulling capstan or drum arrangement driven by a variable speed gear motor with the cord running through the pulley arrangement to a load cell and then to the top of the magnetic drive head.
To determine the gel strength development oE cement slurry under down hole conditions, this equipment was speci-fically designed for measuring static gel strength ater a stirring period that simulated slurry placement. The equip-ment is designed to operate at a max~mum tempeature of 400F
at 10,000 psi. The low friction magnetic drive allows the slurry to be stirred while monitoring consistency during the stirring time. A~ter simulating placement time, the motor is shut ofE and the cord pulling system is attached to the magnetic drive head. Static gel strength is determined by continuously measuring the torque required to rotate the :lZ~6~30 paddle at a very slow speed (O.5 to 2.0 per minu-te). At such speeds, a magnetic drive has very low friction and very accurate torque measurements can be made. Since the torque measuring system consists of a cord pulling capstan or drum arrangement driven by a variable speed gear motor, accurate continuous rotation and means for continuously rec~rding the torque are provided. The gel strength i5 then calculated from the torque measureme,nt and the vessel geometry. The slow movement of the paddle allows static gel strength to be measured but does not inhibit gel strength development.
Continuous static gel strength values can be measured up to a maximum of 1000 lbs/100 ft2.
The standard thixotropic test procedure is as follows:
1. stir the slurry wi-th the magnetic drive consistometer for one hour while increasing temperature and pressure Erom ambient conditions to bottom hole cir-culating temperature tsHCT~ and bottom hole pressure ; (BHP) according to schedule;
2. after one hour of stirring, set static for 15 minutes while continuall~ measuring static gel strength;
' 3. after a static period of 15 minutes, stir for 15 minutes while continually measuring consistency; and
4. rapeat static and stirring times a total of three times.
' -23-l~S~
In the data that is developed, one basic slurry com-position is tested. Tllis slurry consists of API Class ~l cement, 0.4% carboxymethylhydroxyethylcellulose by weight of cement, 44~ water by weight of cement and retarder as given in Table I.
. Table I provides the range of temperatures, pressures : and retarder amounts used in each simulated well condition.
~he temperature range varies from 140F to 275F. The amount of retarder utilized is sufficient to provide at least 3~ hours thickening time at test conditions where . ~ thickening time is taken as the definition given in API
SpeciEication 10.
: ~2~-~:
, '~;
~536~
-TABLE I
Test Conditions and Retarder Amounts Temperature Pressure Percent by Weight ( ~F ) ~pSi ) _ Retarder*
140 6000 0.4 ` 170 8000 102 ``
:~ 180 8000 1.2 200 8000 1.6 215 8000 2.0 ` 245 8000 2.2 275 8000 2.4 ` :' *The retarder used is a 1:1 mi~ture of c~lcium lig~o-:: ` sul~onate and potassium pentaborate tetrahydrate.
Table II provides the physical and chemical propertiesof the compounds tested.
': ' ;~' .
~' .
;:' :
.
- ~S3~
, TABLE II
Physical and Chemical Properties of Canpounds Considered as Thixotropic Cement Additives Physical Compound Fonn ___ Ch~nical Description _ __ Zirconium Solid Zirconium oxychloride (zirconyl chloride) oxychloride -ZrCC12 zirconi~n Liquid Zirconium chelate of acetylacetone acetylacetonate Titani~n Liquid Ti-tanium oxychloride (TiCC12) oxychloride Titaniurn Liquid triethanol- (non-aqueous) Prepared by reaction oE titani~n amine isopropoxide with two moles of tri-ethanolamine.
Ti(oCH(CH3)2)4 ~ 2N(cH2cH2oH)3 ->
(c3H7o)2Ti[ocH2cH2N(cH2cH2oH)2]2 The two moles of isopropyl alcohol are left in the reaction mixture. Thus, this compound consists of triethanolamine titanate plus isopropyl alcohol.
Titanium Solid l'itanium Monotriethanolamine, monotriethanol- [N(CH2CH20-)3]Ti[0CH(CH3)2], contains ~nine about 19.0% titaniunt by weight.
Titanium mono- Solid A mixture oE 57% titanium monotriethanol~
triethanolamine plus amine and 43% fructose by weight fructose (slend I) Titanium mono- Solid A mixture of 73% titanium monotriethanol-triethanolarnine plus amine and 27% fructose by weight fructose (Blend II) Titanium Solid Titanium triethanolamune deposited on triethanolamine diatomaceous earth. Contains about deposited on 4.1% Ti by weight diataraceous earth Titanium' Liquid Solution of titanium monotriethanolamine monotriethanol- containing about 7.6% Ti by weight amine solution ':
~IILZ~36~0 Table II (Continued) ;
_ Physical CanPound Form Chemical Descri tion P
Hydrolyzed, Solid organic titanate (chelate) from hydro-partially poly- lyzed titaniwm acetylacetonate. Prepared merized titanium by controlled addition of water as ; acetylacetonate illustrated below.
Ti(cl12toc(cH3)=cHcocH3]2 ~ 2H20 ->
Ti(OH)2[CC(CH3)=OEICOCH3)2 ~ 2ECl Ti (OH ) 2 (0C(CH3)=CHCOCH3)2 ~ H20 -~
partially polymerized, solid product.
Titanium Liquld Prepared by the reaction of titanium lactate (a~ueous) isopropoxide with ~wo moles of lactic acid in presence of water.
Ti(oCH(CH3)2)4 + 2CH3CH~OH)COOH ->
[Ti(OH)2(0CH(CH3)COO )2][H-~]2 ~ 4C3H70H
The acidic protons are neutralized wlth ammoniwm hydroxide. This productl~y be described as the ammonium salt of tita-nium lactate. However, the structure of this product is complicated by polymeri-zation of the titanium chelate to same degree.
Polymerized Solid Polymerized titanium lact~t~.
titanium Prepared from the titanium lactate.
lactate Extent of polymerization has been increased to insolublize the chelate and yield a solid containing about 2l.4~ Ti.
Lactic acid Solid One mole of lactic acid reacted with two ~` reacted with moles of hydrated Tio2. Ti content is hydrated Tio2 about 20.3% by weight Titanium Liquid Tartaric acid analog of titanium lactate.
tartrate Contains about 8.2% Ti by weight Titanium malate Solid Titanium malate which has been spray dried. Contains about 7.9% Ti by weight Titanium Liquid Prepared b~ the reaction of titanium acetylacetonate (non-aqueous) isopropoxide with two moles of acetylace-tone.
Ti(OCH(CH3)2)4 ~ 2tCH3COCH2COCH3) ->
Ti(oc3H7)2[oc(cH3)=caocH3]2 ~ 2C3H70H
`~ The two moles of isopropyl alcohol are left in tha reaction mixture.
, ~;
' : ` ~X5~i30 Table III provides the actual data obtained. The addi-tive description along with the amount of additive used (by weight of cement), temperatures and actual get strength measurements are shown. The retarder level at each tem-perature is given in Table I. The gel strengths given are the maximum strength in pounds per 100 feet square reached during each 15 static minute period.
.~
.
: ' , !.
TAELE III
Gel Strength Measurementsa Percent Gel Strength : Ad~ition Temperature ~lbs/100 ft2_ ; Additive ~bwc)' tF) 1 2 3 None ~0- 140 12 30 70 ~- zirconium 1.0 140 60 70 60 oxychloride 1.0 200 75 100 95 Zirconium 0.5 140 75 100 160 : acetylacetonate Titanium 0.5 140 365 - -; . oxychloride Titanium 0.25 140 30 40 32 triethanolamine 0.50 140 O 0 30 0.50 200 350 205 212 0.50 275 305 310 225 Titanium 0.25 140 50 6 15 monotriethanol- 0.25 140 40 20 15 amine 0.50 140 50 50 50 :~ 0.50 140 25 25 25 0.25 180 200 320 270 0.2~ 215 500 500 500 : 0.25 275 265 250 220 0.50 275 225 500 500 :~ .
Ti~anium mono- 0.50 140 500 500 500 triethanolamine 0.50 275 80 90 85 plus fructose 0.50 275 70 100 100 :, (Blend I) Titanium mona- 0.25 140 400 500 triethanolamine 0.50 140 500 500 500 plus fructose 0.50 180 200 210 (~lend II) 0.50 215 500 500 500 0.50 275 500 500 500 Titanium tri- 0.50 140 135 120 100 ethanolamine depcsited on . diatomaceaus earth .
~: .
' , , . . .
~: , Gel Strength Measur~nentsa Percent GR1 Strength Addition T~nperature (lbs/100 ft2 _ Additive (bwc) (F) 1 2 3 Titanium mono-0.25 180 500 200 250 triethanolamine 0.50 180 450 500 500 solution Hydrolyzed, O.S 140 205 200 205 partially poly-merized titanium acetylacetonate Titanium Lactate 0.25 170 160 200 215 Polymerized 0.5 275 270 330 235 titanium lactate Lactic acid 0.5 140 350 400 300 reacted with 0.5 200 160 160 195 hydrated Tio20.5 275 40 35 40 Titanium tartrate 0.5 140 115 150 155 0.5 275 180 390 280 Titanium malate 0.5 140 500 500 500 0.5 275 20 40 45 Titanium 0.5 245 450 500 500 acetylacetonateb , a 91urry ccmpo~ition: Class H Cement, 0.4~ aMHECt 44~ H20 b Replacement oE CMHEC with HEC in slurry formulation . ~
:~
.
; -30-s;~
The foregoing data indicates the operability of alkano-lamine titanium chelates in crosslinking CMHEC to impart thixotropic properties to cement composi-tions.
Exam~le 2 i A cement composition of the present invention is used in carrying out a primary cementing job in the field. The well conditions are as follows:
,~ Total depth: 12,000 ft.
` Wellbore size: 6~ inches Casing size: 2-7/8 inch long string sottom hole circulating temperature: 239F
~ottom hole static temperature: 300F
Well fluid: 15.4 lbs/gal mud Displacement fluid: 2~ KCl wa-ter A slurry having the following composition is first pre-pared and tested in the laboratory:
Class H Cament ~ 30~ coarse silica + 4~ CMHEC
+ .5% potassium pentaborate + .5% calcium ligno-sulfonate ~` ~ .25% titanium triethanolamine Slurry density - 16.4 lbs/gal Slurry volume - 1.35 ft3/sk Slurry water - 5.2 gal/sk :~Z~i3~
The laboratory gel strength tests indicate this slurry develops static gel strength o 500 lbs/lU0 ft2 in 20 minu-tes at a bottom hole circulating temperature of 240F and a pressure of ~000 psi. The job is run and considered suc-cessful by the customer. No gas flow is observed on the A' well and the casing shoe withstands the pressure test.
Adequate compressive strength is developed in good time after placement of the slurry.
., ; Example 3 A cement composition oE the present invention is used in -carrying out a cementing job in the area oE Monahans, Texas.
The well conditions are as Eollows:
Total depth: 21,300 ft.
Depth of last casing: 10,646 ft.
Liner ~ize: 5~ inches ~lole size: 8~ inches :~ Top of cement: 10,600 Et~
Bottom hole static temperature: 320F
Bottom hole circulating temperature: 294F
Static temperature at top of cement: 150F
~ Mud density: 11.5 lbs/gal ~invert '~ emulsion) Cement density: 13.5 lbs/gal Due to the extreme well conditions, conventional cement formulations tested do not achieve ini-tial sets at top of cement conditions even~after 72 hours curing time.
~ -32-: .
~S3~
. . ~
A cement slurry of the following composi-tion is prepared and tested:
[A mixture oE 65~ by volume Class H cement and 35%
by volume fly ash] -~ 17.5%* fine silica ~ 0.5%
hydroxyethylcellulose + 0.5% carboxymethylhydroxy-ethylcellulose ~ 0.8~ calcium lignosulf3nate ~ 0.8 ~; potassium pentaborate ~ 0.5% titanium triethanola-mine.
(*All additive percents are by weight of the cement, fly ash mixture.) The above described cement slurry has the following compressive strengths with a thickening time of 5 hours 54 ;~
minutes.
Compressive Stren~hs Temperature~oursPSI
, , 48 1000 ~, 150F 24 400 ~ .
~; 48 500 - The job is conducted and hard cement is found 400 feet on top of the liner in 48 hours and the liner lap tests to 5000 psi.
.~ ' .
' -23-l~S~
In the data that is developed, one basic slurry com-position is tested. Tllis slurry consists of API Class ~l cement, 0.4% carboxymethylhydroxyethylcellulose by weight of cement, 44~ water by weight of cement and retarder as given in Table I.
. Table I provides the range of temperatures, pressures : and retarder amounts used in each simulated well condition.
~he temperature range varies from 140F to 275F. The amount of retarder utilized is sufficient to provide at least 3~ hours thickening time at test conditions where . ~ thickening time is taken as the definition given in API
SpeciEication 10.
: ~2~-~:
, '~;
~536~
-TABLE I
Test Conditions and Retarder Amounts Temperature Pressure Percent by Weight ( ~F ) ~pSi ) _ Retarder*
140 6000 0.4 ` 170 8000 102 ``
:~ 180 8000 1.2 200 8000 1.6 215 8000 2.0 ` 245 8000 2.2 275 8000 2.4 ` :' *The retarder used is a 1:1 mi~ture of c~lcium lig~o-:: ` sul~onate and potassium pentaborate tetrahydrate.
Table II provides the physical and chemical propertiesof the compounds tested.
': ' ;~' .
~' .
;:' :
.
- ~S3~
, TABLE II
Physical and Chemical Properties of Canpounds Considered as Thixotropic Cement Additives Physical Compound Fonn ___ Ch~nical Description _ __ Zirconium Solid Zirconium oxychloride (zirconyl chloride) oxychloride -ZrCC12 zirconi~n Liquid Zirconium chelate of acetylacetone acetylacetonate Titani~n Liquid Ti-tanium oxychloride (TiCC12) oxychloride Titaniurn Liquid triethanol- (non-aqueous) Prepared by reaction oE titani~n amine isopropoxide with two moles of tri-ethanolamine.
Ti(oCH(CH3)2)4 ~ 2N(cH2cH2oH)3 ->
(c3H7o)2Ti[ocH2cH2N(cH2cH2oH)2]2 The two moles of isopropyl alcohol are left in the reaction mixture. Thus, this compound consists of triethanolamine titanate plus isopropyl alcohol.
Titanium Solid l'itanium Monotriethanolamine, monotriethanol- [N(CH2CH20-)3]Ti[0CH(CH3)2], contains ~nine about 19.0% titaniunt by weight.
Titanium mono- Solid A mixture oE 57% titanium monotriethanol~
triethanolamine plus amine and 43% fructose by weight fructose (slend I) Titanium mono- Solid A mixture of 73% titanium monotriethanol-triethanolarnine plus amine and 27% fructose by weight fructose (Blend II) Titanium Solid Titanium triethanolamune deposited on triethanolamine diatomaceous earth. Contains about deposited on 4.1% Ti by weight diataraceous earth Titanium' Liquid Solution of titanium monotriethanolamine monotriethanol- containing about 7.6% Ti by weight amine solution ':
~IILZ~36~0 Table II (Continued) ;
_ Physical CanPound Form Chemical Descri tion P
Hydrolyzed, Solid organic titanate (chelate) from hydro-partially poly- lyzed titaniwm acetylacetonate. Prepared merized titanium by controlled addition of water as ; acetylacetonate illustrated below.
Ti(cl12toc(cH3)=cHcocH3]2 ~ 2H20 ->
Ti(OH)2[CC(CH3)=OEICOCH3)2 ~ 2ECl Ti (OH ) 2 (0C(CH3)=CHCOCH3)2 ~ H20 -~
partially polymerized, solid product.
Titanium Liquld Prepared by the reaction of titanium lactate (a~ueous) isopropoxide with ~wo moles of lactic acid in presence of water.
Ti(oCH(CH3)2)4 + 2CH3CH~OH)COOH ->
[Ti(OH)2(0CH(CH3)COO )2][H-~]2 ~ 4C3H70H
The acidic protons are neutralized wlth ammoniwm hydroxide. This productl~y be described as the ammonium salt of tita-nium lactate. However, the structure of this product is complicated by polymeri-zation of the titanium chelate to same degree.
Polymerized Solid Polymerized titanium lact~t~.
titanium Prepared from the titanium lactate.
lactate Extent of polymerization has been increased to insolublize the chelate and yield a solid containing about 2l.4~ Ti.
Lactic acid Solid One mole of lactic acid reacted with two ~` reacted with moles of hydrated Tio2. Ti content is hydrated Tio2 about 20.3% by weight Titanium Liquid Tartaric acid analog of titanium lactate.
tartrate Contains about 8.2% Ti by weight Titanium malate Solid Titanium malate which has been spray dried. Contains about 7.9% Ti by weight Titanium Liquid Prepared b~ the reaction of titanium acetylacetonate (non-aqueous) isopropoxide with two moles of acetylace-tone.
Ti(OCH(CH3)2)4 ~ 2tCH3COCH2COCH3) ->
Ti(oc3H7)2[oc(cH3)=caocH3]2 ~ 2C3H70H
`~ The two moles of isopropyl alcohol are left in tha reaction mixture.
, ~;
' : ` ~X5~i30 Table III provides the actual data obtained. The addi-tive description along with the amount of additive used (by weight of cement), temperatures and actual get strength measurements are shown. The retarder level at each tem-perature is given in Table I. The gel strengths given are the maximum strength in pounds per 100 feet square reached during each 15 static minute period.
.~
.
: ' , !.
TAELE III
Gel Strength Measurementsa Percent Gel Strength : Ad~ition Temperature ~lbs/100 ft2_ ; Additive ~bwc)' tF) 1 2 3 None ~0- 140 12 30 70 ~- zirconium 1.0 140 60 70 60 oxychloride 1.0 200 75 100 95 Zirconium 0.5 140 75 100 160 : acetylacetonate Titanium 0.5 140 365 - -; . oxychloride Titanium 0.25 140 30 40 32 triethanolamine 0.50 140 O 0 30 0.50 200 350 205 212 0.50 275 305 310 225 Titanium 0.25 140 50 6 15 monotriethanol- 0.25 140 40 20 15 amine 0.50 140 50 50 50 :~ 0.50 140 25 25 25 0.25 180 200 320 270 0.2~ 215 500 500 500 : 0.25 275 265 250 220 0.50 275 225 500 500 :~ .
Ti~anium mono- 0.50 140 500 500 500 triethanolamine 0.50 275 80 90 85 plus fructose 0.50 275 70 100 100 :, (Blend I) Titanium mona- 0.25 140 400 500 triethanolamine 0.50 140 500 500 500 plus fructose 0.50 180 200 210 (~lend II) 0.50 215 500 500 500 0.50 275 500 500 500 Titanium tri- 0.50 140 135 120 100 ethanolamine depcsited on . diatomaceaus earth .
~: .
' , , . . .
~: , Gel Strength Measur~nentsa Percent GR1 Strength Addition T~nperature (lbs/100 ft2 _ Additive (bwc) (F) 1 2 3 Titanium mono-0.25 180 500 200 250 triethanolamine 0.50 180 450 500 500 solution Hydrolyzed, O.S 140 205 200 205 partially poly-merized titanium acetylacetonate Titanium Lactate 0.25 170 160 200 215 Polymerized 0.5 275 270 330 235 titanium lactate Lactic acid 0.5 140 350 400 300 reacted with 0.5 200 160 160 195 hydrated Tio20.5 275 40 35 40 Titanium tartrate 0.5 140 115 150 155 0.5 275 180 390 280 Titanium malate 0.5 140 500 500 500 0.5 275 20 40 45 Titanium 0.5 245 450 500 500 acetylacetonateb , a 91urry ccmpo~ition: Class H Cement, 0.4~ aMHECt 44~ H20 b Replacement oE CMHEC with HEC in slurry formulation . ~
:~
.
; -30-s;~
The foregoing data indicates the operability of alkano-lamine titanium chelates in crosslinking CMHEC to impart thixotropic properties to cement composi-tions.
Exam~le 2 i A cement composition of the present invention is used in carrying out a primary cementing job in the field. The well conditions are as follows:
,~ Total depth: 12,000 ft.
` Wellbore size: 6~ inches Casing size: 2-7/8 inch long string sottom hole circulating temperature: 239F
~ottom hole static temperature: 300F
Well fluid: 15.4 lbs/gal mud Displacement fluid: 2~ KCl wa-ter A slurry having the following composition is first pre-pared and tested in the laboratory:
Class H Cament ~ 30~ coarse silica + 4~ CMHEC
+ .5% potassium pentaborate + .5% calcium ligno-sulfonate ~` ~ .25% titanium triethanolamine Slurry density - 16.4 lbs/gal Slurry volume - 1.35 ft3/sk Slurry water - 5.2 gal/sk :~Z~i3~
The laboratory gel strength tests indicate this slurry develops static gel strength o 500 lbs/lU0 ft2 in 20 minu-tes at a bottom hole circulating temperature of 240F and a pressure of ~000 psi. The job is run and considered suc-cessful by the customer. No gas flow is observed on the A' well and the casing shoe withstands the pressure test.
Adequate compressive strength is developed in good time after placement of the slurry.
., ; Example 3 A cement composition oE the present invention is used in -carrying out a cementing job in the area oE Monahans, Texas.
The well conditions are as Eollows:
Total depth: 21,300 ft.
Depth of last casing: 10,646 ft.
Liner ~ize: 5~ inches ~lole size: 8~ inches :~ Top of cement: 10,600 Et~
Bottom hole static temperature: 320F
Bottom hole circulating temperature: 294F
Static temperature at top of cement: 150F
~ Mud density: 11.5 lbs/gal ~invert '~ emulsion) Cement density: 13.5 lbs/gal Due to the extreme well conditions, conventional cement formulations tested do not achieve ini-tial sets at top of cement conditions even~after 72 hours curing time.
~ -32-: .
~S3~
. . ~
A cement slurry of the following composi-tion is prepared and tested:
[A mixture oE 65~ by volume Class H cement and 35%
by volume fly ash] -~ 17.5%* fine silica ~ 0.5%
hydroxyethylcellulose + 0.5% carboxymethylhydroxy-ethylcellulose ~ 0.8~ calcium lignosulf3nate ~ 0.8 ~; potassium pentaborate ~ 0.5% titanium triethanola-mine.
(*All additive percents are by weight of the cement, fly ash mixture.) The above described cement slurry has the following compressive strengths with a thickening time of 5 hours 54 ;~
minutes.
Compressive Stren~hs Temperature~oursPSI
, , 48 1000 ~, 150F 24 400 ~ .
~; 48 500 - The job is conducted and hard cement is found 400 feet on top of the liner in 48 hours and the liner lap tests to 5000 psi.
.~ ' .
Claims (6)
1. A method of cementing a subterranean zone penetrated by a well bore comprising:
providing a set retarded aqueous hydraulic cement slurry;
admixing with said cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of:
A triethanolamine titanium chelate represented by one of the formulae:
wherein R is independently an alkyl or aryl group, wherein R1 is independently OC3H7, OH or a halogen atom, and partially polymerized chelates produced from said triethanolamine chelates, and placing said cement slurry across said zone or zones by way of said well bore and allowing said cement slurry to set into a hard mass therein having enhanced compressive strength.
providing a set retarded aqueous hydraulic cement slurry;
admixing with said cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of:
A triethanolamine titanium chelate represented by one of the formulae:
wherein R is independently an alkyl or aryl group, wherein R1 is independently OC3H7, OH or a halogen atom, and partially polymerized chelates produced from said triethanolamine chelates, and placing said cement slurry across said zone or zones by way of said well bore and allowing said cement slurry to set into a hard mass therein having enhanced compressive strength.
2. The method of claim 1, wherein the delayed retarder neutralizer is present in said composition in an amount in the range of from about 0.05% to about 1.5% by weight of dry cement therein.
3. A method of cementing a subterranean zone penetrated by a well bore comprising:
providing a set retarded aqueous hydraulic cement slurry;
admixing with said cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of:
a titanium chelate represented by one of the formulae:
wherein R1 is independently hydrogen, an alkyl group, or a hydroxyalkyl group, R2 is independently ethylene, trimethylene or isopropylene, and R3 is independently an alkyl or aryl group, wherein R1 is independently hydrogen, an alkyl group or a hydroxyalkyl group, R2 is independently ethylene, trimethylene or isopropylene, and R4 is independently OC3H7, OH or a halogen atom;
whereby said chelate molecule contains at least one hydroxyalkyl and placing said cement slurry across the zone or zones by way of said well bore and allowing said cement slurry to set into a hard mass therein having enhanced compressive strength.
providing a set retarded aqueous hydraulic cement slurry;
admixing with said cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of:
a titanium chelate represented by one of the formulae:
wherein R1 is independently hydrogen, an alkyl group, or a hydroxyalkyl group, R2 is independently ethylene, trimethylene or isopropylene, and R3 is independently an alkyl or aryl group, wherein R1 is independently hydrogen, an alkyl group or a hydroxyalkyl group, R2 is independently ethylene, trimethylene or isopropylene, and R4 is independently OC3H7, OH or a halogen atom;
whereby said chelate molecule contains at least one hydroxyalkyl and placing said cement slurry across the zone or zones by way of said well bore and allowing said cement slurry to set into a hard mass therein having enhanced compressive strength.
4. The method of claim 3, wherein the delayed retarder neutralizer is present in said composition in an amount in the range of from about 0.05% to about 1.5% by weight of dry cement therein.
5. A method of cementing a subterranean zone penetrated by a well bore comprising:
providing a set retarded aqueous hydraulic cement slurry;
admixing with said cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of:
a triethanolamine titanium chelate represented by the formula:
wherein R is independently an oxyalkyl group, an oxyaryl group, OH or a halogen, R3 is independently ethylene, trimethylene or isopropylene, R4 and R5 are independently hydrogen, an alkyl group, a hydroxyalkyl group or an aminoalkyl group, R6 is an oxyalkyl group, and R7 is independently hydrogen, an alkyl group, a hydroxyalkyl group or an aminoalkyl group, R7 is independently hydrogen, alkyl, hydroxyalkyl or an aminoalkyl group;
whereby said chelate molecule contains at least one hydroxyalkyl group;
and placing said cement slurry across the zone or zones by way of said well bore and allowing said cement slurry to set into a hard mass therein having enhanced compressive strength.
providing a set retarded aqueous hydraulic cement slurry;
admixing with said cement slurry to enhance the compressive strength development thereof after placement, an effective amount of a delayed retarder neutralizer selected from the group consisting of:
a triethanolamine titanium chelate represented by the formula:
wherein R is independently an oxyalkyl group, an oxyaryl group, OH or a halogen, R3 is independently ethylene, trimethylene or isopropylene, R4 and R5 are independently hydrogen, an alkyl group, a hydroxyalkyl group or an aminoalkyl group, R6 is an oxyalkyl group, and R7 is independently hydrogen, an alkyl group, a hydroxyalkyl group or an aminoalkyl group, R7 is independently hydrogen, alkyl, hydroxyalkyl or an aminoalkyl group;
whereby said chelate molecule contains at least one hydroxyalkyl group;
and placing said cement slurry across the zone or zones by way of said well bore and allowing said cement slurry to set into a hard mass therein having enhanced compressive strength.
6. The method of claim 5, wherein the delayed retarder neutralizer is present in said composition in an amount in the range of from about 0.05% to about 1.5% by weight of dry cement therein.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000568264A CA1253680A (en) | 1984-11-06 | 1988-05-31 | Method of cementing a subterranean zone |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/668,767 US4582139A (en) | 1983-10-11 | 1984-11-06 | Set retarded cement compositions and well cementing methods |
| US668,767 | 1984-11-06 | ||
| CA000494611A CA1249713A (en) | 1984-11-06 | 1985-11-05 | Set retarded cement compositions and well cementing methods |
| CA000568264A CA1253680A (en) | 1984-11-06 | 1988-05-31 | Method of cementing a subterranean zone |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000494611A Division CA1249713A (en) | 1984-11-06 | 1985-11-05 | Set retarded cement compositions and well cementing methods |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1253680A true CA1253680A (en) | 1989-05-09 |
Family
ID=25670827
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000568264A Expired CA1253680A (en) | 1984-11-06 | 1988-05-31 | Method of cementing a subterranean zone |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1253680A (en) |
-
1988
- 1988-05-31 CA CA000568264A patent/CA1253680A/en not_active Expired
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