CA2046714A1 - Accelerating set of retarded cement - Google Patents
Accelerating set of retarded cementInfo
- Publication number
- CA2046714A1 CA2046714A1 CA002046714A CA2046714A CA2046714A1 CA 2046714 A1 CA2046714 A1 CA 2046714A1 CA 002046714 A CA002046714 A CA 002046714A CA 2046714 A CA2046714 A CA 2046714A CA 2046714 A1 CA2046714 A1 CA 2046714A1
- Authority
- CA
- Canada
- Prior art keywords
- cement
- formate
- drilling fluid
- present
- accelerator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Landscapes
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
ACCELERATING SET OF RETARDED CEMENT
ABSTRACT
What is disclosed is a method of accelerating the set of a retarded cement. The cement may range from a drilling fluid containing dispersants or retarders that will slow down the set of the drilling fluid when cementitious fluid is added thereto, through overwashing, or treating a retarded primary or remedial cement that may have been injected into fractures or areas within a well to overwashing a plug or any volume of retarded cement that needs to be set in a well.
The specific uses are discussed.
ABSTRACT
What is disclosed is a method of accelerating the set of a retarded cement. The cement may range from a drilling fluid containing dispersants or retarders that will slow down the set of the drilling fluid when cementitious fluid is added thereto, through overwashing, or treating a retarded primary or remedial cement that may have been injected into fractures or areas within a well to overwashing a plug or any volume of retarded cement that needs to be set in a well.
The specific uses are discussed.
Description
Docket No. DF-673 (DP 50 6-1041 ACCE~ERATING SET OF RETARDED CEMEN~
SPECIFICATION
Field of the Invention This invention relates to cementing oil and ~as wells. More particularly, this invention relates to accelerating set of cement that is highly retarded:
such as, retarding drilling 1uid converted to cement:
or retarded con~entional cement~, including cement slurries that mi~ht commingle with a drilling fluid or otherwis~ become conta~inated with a retarding chemical.
Back~round of ~he Inven-tiQn The prior art i5 replete with a wide variety o~
both inorganic and organic cQment accelerators. In a co-pending application, Docket DP-50-~-980~, serial number 07/131,878, entitled 'tCEMENTING OIL AND GAS
~ELLS USING CONV~RTED D~ILLING FLUI~" o~ Whlch the present co-inventors are co-inven~or~ and having the same assignee, there was discus~ed ~he completion o~
oil and gas well~ by convertin~ of a drilling ~luid, or "mud", to a cement, and several patents were cited therein Which disclose compositions for accomplishing thi~.
In that application it was noted that ef~orts to convert drilling fluid containing cementitious materials have posed problems such as increased viscosi~y due to ~loccula~ion as cementitious material is added to the drilling mud, and subsequently pumped into the wellbore. Therein was ci~ed U.S. 3,499,~91, ,'~", ~ ,JJ .
which describes di~ficulties with yelling characteristics and, particularly, temperaturP
sensitivity.
In both primary and remedial applications, it is also sometimPs desirable to set retarded cement formulations more rapidly. Typically cement is retarded for pumping into wellbore annuli or perforations where it is desirable to have a contxolled viscosity and set ti~e to permit safe cement slurry placement, but also desirable to have the slurry set rapidly after placement. For example, to allow ample time for placement of c~ment formulations before set, retarders are ~requently added to prevent the development of high viscosities or premature setting of cement slurry during the pumping and ~queezing into the annular ~oids or perforations. Yet, these retarders can also delay the setting of the cement for long periods o~ time after placement even under in situ conditions. Excessive set times contribute to high operational costs due to rig ~ime ~tandby. Thus, ik is desirable that a compatible accelerator be employed in some fashion to greatly reduce the set time fsr the cement.
The same i6 krue when setting cement in the form o~ plugs in the wellbore. This may be ~or pluggillg the well; form~tion pack of~, or seal ofP between productive fo~mations or otherwise; and/or or wellbore deviation. Fre~uantly, gravity or other ~actors cause the cement plug to intermin~le or become contaminated with the drilling fluid. The drilling fluid is an e~ective cement ~et r~tarder and prevents or de].ays the set of the cement plug. In any event, it is sometimes desirable th~t an over wash be provided to accelerate the set of the cement strength development without adversely af~ecting pumping time.
Summary of the Inventio~
Accordingly, it is an objec~ o~ the present invention to provide improved composition and method that will increase the rate of set of retarded cem~nt regardless of what application it is employed in.
It is a specific object of this invention to provide a composition in which the drilling fluid can be converted to a cement which will ~et up within a desirable time after the cementitious material i5 added thereto.
These and other objects will become apparent from the descriptive matter which follows.
In a broad aspect of this invention, there is provided a compatible accelerator for accelerating the set strength development rate of a retarded cement in any application.
In accordance with one aspect of this inventio~, there i8 provided a method of accelerating the set of highly retarded cementi by overwa~hing a r~tarded cement composition with a compatible accelerator that will decrease the setting tim~ for the cement in annular voids or perforations and/or in a plug in a wellbore.
In accordance wlth another aspect of th:is invention, there i8 provided a cement composition for cementing any design~ted section o~ a wellbore wherein the space in the wellbore i~ occupied by a drilllng fluid. The composition comprises a quantity of the drilling ~luid containing YiSCoSity control agents which ~erve as re~arder~ when the cementitious ~aterial is added; a dry cement material, a dispersant, and an accelerator that is compatible.
By compatible accelerators i~ meant an accelerator that contains a material that will fo~n ~o~n~te ions without a violent reaction with basic cement slurry constituents in the cement slurry. We have obtained excellent results with formamide and know that it works regardless o~ whether or not the theory reyarding formate ion is correct. Other sources of formate ion in cement slurry are salts of formic acid and esters of formic acid. For example, it is known that the first four carbon ester~ of formic acid will react satisfactorily ~ast to give good results. These esters include the methyl ester of ~ormic acid, sometimes called methyl formate; the ethyl ester of formic acid, sometimes called ethyl formate; the propyl, both iso-and normal-propyl estsr of for~ic acid, sometimes called, respectively, iso-propyl formate or normal-propyl formate; and the butyl, iso-, normal-, or tertiary-butyl ester of ormic acid, sometimes called iso-, normal- or t-butyl fo~ate. Whether or not the theory of hydrolysis i5 correct, we do obtain excellent results with the~e fir~t ~our carbon esters o~ formic acid and know that they worX regardless of whether or not ~he theory ia correct~
In another aspect, this invention provides method ~or treating a well in which the suhterrarlean formation about the well may or ~ay not be ~ractured and a retarded cement slurry is applied to seal o~
annular voids and per~orations~ There is also provided the method for improvement o~ washing over th~ cement with a solution o~ a compatible organic accelerator such as the material that w~ll yield formate ions, as delinea ed hereinbefore.
In another aspect of thi~ invention there is provided a method for accelerating a cement plug in a well completed in a subterranean ~ormation where cement is pumped into the well and allowed to set to fo~n a plug therewithin~ The improvement comprises either washing over the cement plug with a ~olution o~ a compatible organic accelerator or pumping the plug into ~ ~J
an interval of the well previously filled with the compatible organic accelerator. The compatible oryanic accelerator is khe material that will yield formate ions in the cement slurry, as d~lineated hereinbe~ore.
These compatible organic accelerators can be employed alone or in combination with o~her known accelerators, such as but not limited to those inorganic accelerator~ like silicates (sodium metasilicate, sodium silicate, or potassium silicate) or chlorid2s (sodium chloride, potassium chloride, or calcium chloride).
Description of Pxeferred ~mbodiments The cunversion of ~ell drilling fluids lnto cement slurries for th~ purposes of cementing in wellbores to casing annulus, and/or performing other wellbore cementing applications i~ attractive for several reasons; one of which would be that a major portion o~
the drilling fluid would not be ~ubject to waste disposal regulations. Moreover, the conversion o~
drilling flùid to a cement ~lurry minimizes the handling o~ drilling ~luid a~ter completion of the well, and minimizes the cement expense, and the mud cement will ef~ect a ~ore nearly compl.ete dl~placement o~ the drllling ~luid.
The convQr~ion oP drilling fluid, or "mud" to a cement slurry is not without some operational problems and undesirable compo~itional changes~ For example, the addition vf cementitious mat~rial such a~ mixtures of lime, ~ilica, alu~ina or lime and magne~ia, silica and alu~ina and iron oxid~, or cement materials such as calcium sulfate and Portland cement to aqueous drilling fluids can substantially increa6e the Visc08ity 0~ the fluid ~ixture and cause ~evere ~locculakion. E~forts to circulate such mixture~ through a wellbore can result in highly unsati~factory circulation rates, ;
restricting flow in the wellbore annulus, increasing pressures, resulting in breakdown of the earth formations in the vicinity of the wellbore. In addition, excessive viscosity contributes to failure of the surface operations to mix the cement slurry proparly. Certain dispersants have been developed for use in these drilling fluids during the drilling operations. These include lignite, ligno-sulfonates, and polyacrylates. Other disper~ants have been used:
particularly, in the situation where it is desired to convert a drilling mud to a set cement. These other dispersants are discus~ed in co-pending application DP
50 6-980A, now serial numb~r 07/131,878.
It is well recognized by those ~killed in the ar~
that these normal constituents of drilling mud also act as retarders, which inhibit the setting of cement slurries. Specifically, it may take a week or longer ~or such converted drilling mud cement~ to set, and it i8 de irable to horten thl~ time.
It is believed helpful to discuss this conversion of drilling mud to cement ln greater detail b0fore looking at other embodiment~ ~or which this inv4ntion is useful. The process for converting a drilling mud to a cement 61urry for cementing a well is di~cu~sed in the above-re~erenc~d serial number 07/131,878, and does not require detailed explanation herein. Details o~
that application are included herein by re~erence.
Expressed otherwise, the operation simply comprises a casing that iB extended into a portion of the formation Prom a wellhead with a ~econd casing extending into the formation further as a wellbore is deepened to form an annulus which may include washouts or void areas behind the casing. The casing is adapted to be in commun~cation with the pump ~or circulating drilling Pluid through the interior of the casing, up the annulu~ and through a return conduit to a storage tank ~J~7,~ J1~,7~
or pit and is recirculated khrough the pump in normal drilling operations. Conventional drilling fluid conditioning devices such as shale shakers, sand separators and related equipment may be employed; but are normally not shown in schematic illustrations in the interest o~ clarity. One method for converting a drilling fluid into a cementitious slurry is the addition o~ premixed quantities from storage of dry blended cement formulation for conduction to a slurry mixing operation. The ~ormulation is added ~o a slurry and mixe~ into the drilling fluid which is thereby converted into a cementitious slurry. It is at this point that it is convenient to add accelerators or the like to at least neutralize the 6et retarding effects of the varlous dispersants that may have ~een present in the drilling fluid, or added to the drilling fluid in the cement conversion process.
As described hereinbefore, compatible accelerators comprise the materials which will yield the formate ions without the violent reaction. We know ~rom experimental data that for~amide will provide excellent results and that th~ ~lrst ~our carbon esters oE formic acid will provide qood result~.
These material~ ar~ di~cussed in Haakh'3 Chemical Dictionary and do not re~uire ~urther description herein.
In thia invention, a compatible accelerator is employed when a concentration range of from 0.05 to about 2.5 gallons per ~arrel of original drilling fluid is present. A better concentration is a range of 0.3 -1.2 gallons per ~arrel of cement ~lurry employed7 The concentration may vary from this for a specific application. For most applications khe optimum concentration is about 0.6 gallons per barrel of cement slurry. This will result of a setting time for the cementitiou3 slurry of approximately twenty-~our hours, which is substantially ~horter than the prior art retarded cements.
When employed in an over wash, the compatible accelerator is in a concentration within the range of 5 percent by weight to 100 percent by weight, the remaindert if any, being water.
As indicated, this invention is useful also when an over wash is employed a~ter squeezing cement through perforations or in casing cracks. A highly retarded cement may be emplaced and then wa~hed over with a solution containing the compatible accelerator; for example, the first four carbon esters of formic acid.
The differential pressure extended from the wellbore into the formation will ~orce the liquid that is employed as the over wash solution containing the cement accelerator into the permeable cement matrix.
Normally, such an over pressure i~ ln the range of from 200 500 pound~ per 6quare inch ( psi) greater in the well than it i5 in the form~tion so it tends to e~fect flushing of the over wa~h solution containing the ce~ent accelerator through t~e hydrating cement matrix.
The compatible accelerator can be employed to mitigate adverse e~ect~ of contamlnation ~rom in situ mixing with ~luids, ~uch as drilling ~luids, in any application. Speciiically, i~ too much ret~rder is pu~
into a cement slurry, an e~ective amount of compatible accelerator can be employed to neutralize the retarder and get it back into the desired range.
In another operation, the ~olution containing the accelerator may be 6potted below a cement to be placed in a well ~o form a plug. Thereafter a spot of liquid containing the cement accel~rator may be positioned above the cement. A ~urfactant may be employed in a small concentration o~ about 0.1 ~1.0 percent (~), if des~red, in th~ preflush~ cement ~lurry, or overflush, l~ /S;
to decrease the interfacial tension and help the surrounding fluids to penetrate into the cement matrix.
The accelerators have the property o~ accelerating the set o~ the cement and have the potential for immediate application in the conversion of mud to cement and as an over wash additive, or Por washing an acceleratiny solution from both above and/or below to produce acceleration of cement nodes in remedial squeeze operations, cement plugs in plugback, kicko~f, whipstock procedures, or cement at the top of liners after liner cementing operations.
EXAMPLE
The ~ollowing example illustrates both a control without this invention and laboratory experiments performed to ~imulate field conditions and show e~fectiveness o~ the accelerator.
EXAMPL~ I
Xn thls exampl~ from 350 cubic c:entimet~ri (cc's), serving as an experimental one barrel quantlty, o~
10.45 pounds (lb~.) per gallon (ppg) Rapid Mud (a trademark o~ Baroid Corp) wa~ employed with 175 cc's serving as 0.5 barrel of water, and 300 lbs. per barrel (coarse grind) Raiser Cement in a quant~ty of 300 grams was employed wikh 2.25 lbs. per barrel (2.25 gram SSMA, which is ~ul~onated styrene ~aleic anhydride copolymer). The result was a retarded cement having a density o~ 12.3 pounds per gallon. This served as a base ~or comparison and had 0 psi compressive strength and had not even begun to ~et up after 4 days, but after 4.6 day~ it gave a compressive strength o~ 50 psi and a~ter 11 day~ gave a compressive strength of 500 ``` ~,;~i i"! ,/1 psi but the pumping time was still about 48~ hours at 94 degrees Fahrenheit.
In contrast, 350 cc's of 10.45 ppg Rapid Mud in 175 cc's water, giving 300 lbs. per barrel ~coarse grind) Xaiser Cement with 3 gms. (lbs. per barrel) SSMA
and 2.4 gal/bbl, or 20 ml., of formamide, gave a compressive strength of 50 psi ~pounds per square inch) after only 18 hours; 460 psi after 4 days and 562 psi after 11 day~. The pumping time remained unchanged at 48+ hours at 94 degrees Fahrenheit.
Although this invention has been described with a certain degree of particularity, it is understood that the present di~closure i8 made only by way of example and that numerous changes in the details of ; construction and the combination and arrangement of part~ may be resorted to without departing fro~ the spirit and the scope of the invention, re~erence being had for the latter purpose to the appended claims.
SPECIFICATION
Field of the Invention This invention relates to cementing oil and ~as wells. More particularly, this invention relates to accelerating set of cement that is highly retarded:
such as, retarding drilling 1uid converted to cement:
or retarded con~entional cement~, including cement slurries that mi~ht commingle with a drilling fluid or otherwis~ become conta~inated with a retarding chemical.
Back~round of ~he Inven-tiQn The prior art i5 replete with a wide variety o~
both inorganic and organic cQment accelerators. In a co-pending application, Docket DP-50-~-980~, serial number 07/131,878, entitled 'tCEMENTING OIL AND GAS
~ELLS USING CONV~RTED D~ILLING FLUI~" o~ Whlch the present co-inventors are co-inven~or~ and having the same assignee, there was discus~ed ~he completion o~
oil and gas well~ by convertin~ of a drilling ~luid, or "mud", to a cement, and several patents were cited therein Which disclose compositions for accomplishing thi~.
In that application it was noted that ef~orts to convert drilling fluid containing cementitious materials have posed problems such as increased viscosi~y due to ~loccula~ion as cementitious material is added to the drilling mud, and subsequently pumped into the wellbore. Therein was ci~ed U.S. 3,499,~91, ,'~", ~ ,JJ .
which describes di~ficulties with yelling characteristics and, particularly, temperaturP
sensitivity.
In both primary and remedial applications, it is also sometimPs desirable to set retarded cement formulations more rapidly. Typically cement is retarded for pumping into wellbore annuli or perforations where it is desirable to have a contxolled viscosity and set ti~e to permit safe cement slurry placement, but also desirable to have the slurry set rapidly after placement. For example, to allow ample time for placement of c~ment formulations before set, retarders are ~requently added to prevent the development of high viscosities or premature setting of cement slurry during the pumping and ~queezing into the annular ~oids or perforations. Yet, these retarders can also delay the setting of the cement for long periods o~ time after placement even under in situ conditions. Excessive set times contribute to high operational costs due to rig ~ime ~tandby. Thus, ik is desirable that a compatible accelerator be employed in some fashion to greatly reduce the set time fsr the cement.
The same i6 krue when setting cement in the form o~ plugs in the wellbore. This may be ~or pluggillg the well; form~tion pack of~, or seal ofP between productive fo~mations or otherwise; and/or or wellbore deviation. Fre~uantly, gravity or other ~actors cause the cement plug to intermin~le or become contaminated with the drilling fluid. The drilling fluid is an e~ective cement ~et r~tarder and prevents or de].ays the set of the cement plug. In any event, it is sometimes desirable th~t an over wash be provided to accelerate the set of the cement strength development without adversely af~ecting pumping time.
Summary of the Inventio~
Accordingly, it is an objec~ o~ the present invention to provide improved composition and method that will increase the rate of set of retarded cem~nt regardless of what application it is employed in.
It is a specific object of this invention to provide a composition in which the drilling fluid can be converted to a cement which will ~et up within a desirable time after the cementitious material i5 added thereto.
These and other objects will become apparent from the descriptive matter which follows.
In a broad aspect of this invention, there is provided a compatible accelerator for accelerating the set strength development rate of a retarded cement in any application.
In accordance with one aspect of this inventio~, there i8 provided a method of accelerating the set of highly retarded cementi by overwa~hing a r~tarded cement composition with a compatible accelerator that will decrease the setting tim~ for the cement in annular voids or perforations and/or in a plug in a wellbore.
In accordance wlth another aspect of th:is invention, there i8 provided a cement composition for cementing any design~ted section o~ a wellbore wherein the space in the wellbore i~ occupied by a drilllng fluid. The composition comprises a quantity of the drilling ~luid containing YiSCoSity control agents which ~erve as re~arder~ when the cementitious ~aterial is added; a dry cement material, a dispersant, and an accelerator that is compatible.
By compatible accelerators i~ meant an accelerator that contains a material that will fo~n ~o~n~te ions without a violent reaction with basic cement slurry constituents in the cement slurry. We have obtained excellent results with formamide and know that it works regardless o~ whether or not the theory reyarding formate ion is correct. Other sources of formate ion in cement slurry are salts of formic acid and esters of formic acid. For example, it is known that the first four carbon ester~ of formic acid will react satisfactorily ~ast to give good results. These esters include the methyl ester of ~ormic acid, sometimes called methyl formate; the ethyl ester of formic acid, sometimes called ethyl formate; the propyl, both iso-and normal-propyl estsr of for~ic acid, sometimes called, respectively, iso-propyl formate or normal-propyl formate; and the butyl, iso-, normal-, or tertiary-butyl ester of ormic acid, sometimes called iso-, normal- or t-butyl fo~ate. Whether or not the theory of hydrolysis i5 correct, we do obtain excellent results with the~e fir~t ~our carbon esters o~ formic acid and know that they worX regardless of whether or not ~he theory ia correct~
In another aspect, this invention provides method ~or treating a well in which the suhterrarlean formation about the well may or ~ay not be ~ractured and a retarded cement slurry is applied to seal o~
annular voids and per~orations~ There is also provided the method for improvement o~ washing over th~ cement with a solution o~ a compatible organic accelerator such as the material that w~ll yield formate ions, as delinea ed hereinbefore.
In another aspect of thi~ invention there is provided a method for accelerating a cement plug in a well completed in a subterranean ~ormation where cement is pumped into the well and allowed to set to fo~n a plug therewithin~ The improvement comprises either washing over the cement plug with a ~olution o~ a compatible organic accelerator or pumping the plug into ~ ~J
an interval of the well previously filled with the compatible organic accelerator. The compatible oryanic accelerator is khe material that will yield formate ions in the cement slurry, as d~lineated hereinbe~ore.
These compatible organic accelerators can be employed alone or in combination with o~her known accelerators, such as but not limited to those inorganic accelerator~ like silicates (sodium metasilicate, sodium silicate, or potassium silicate) or chlorid2s (sodium chloride, potassium chloride, or calcium chloride).
Description of Pxeferred ~mbodiments The cunversion of ~ell drilling fluids lnto cement slurries for th~ purposes of cementing in wellbores to casing annulus, and/or performing other wellbore cementing applications i~ attractive for several reasons; one of which would be that a major portion o~
the drilling fluid would not be ~ubject to waste disposal regulations. Moreover, the conversion o~
drilling flùid to a cement ~lurry minimizes the handling o~ drilling ~luid a~ter completion of the well, and minimizes the cement expense, and the mud cement will ef~ect a ~ore nearly compl.ete dl~placement o~ the drllling ~luid.
The convQr~ion oP drilling fluid, or "mud" to a cement slurry is not without some operational problems and undesirable compo~itional changes~ For example, the addition vf cementitious mat~rial such a~ mixtures of lime, ~ilica, alu~ina or lime and magne~ia, silica and alu~ina and iron oxid~, or cement materials such as calcium sulfate and Portland cement to aqueous drilling fluids can substantially increa6e the Visc08ity 0~ the fluid ~ixture and cause ~evere ~locculakion. E~forts to circulate such mixture~ through a wellbore can result in highly unsati~factory circulation rates, ;
restricting flow in the wellbore annulus, increasing pressures, resulting in breakdown of the earth formations in the vicinity of the wellbore. In addition, excessive viscosity contributes to failure of the surface operations to mix the cement slurry proparly. Certain dispersants have been developed for use in these drilling fluids during the drilling operations. These include lignite, ligno-sulfonates, and polyacrylates. Other disper~ants have been used:
particularly, in the situation where it is desired to convert a drilling mud to a set cement. These other dispersants are discus~ed in co-pending application DP
50 6-980A, now serial numb~r 07/131,878.
It is well recognized by those ~killed in the ar~
that these normal constituents of drilling mud also act as retarders, which inhibit the setting of cement slurries. Specifically, it may take a week or longer ~or such converted drilling mud cement~ to set, and it i8 de irable to horten thl~ time.
It is believed helpful to discuss this conversion of drilling mud to cement ln greater detail b0fore looking at other embodiment~ ~or which this inv4ntion is useful. The process for converting a drilling mud to a cement 61urry for cementing a well is di~cu~sed in the above-re~erenc~d serial number 07/131,878, and does not require detailed explanation herein. Details o~
that application are included herein by re~erence.
Expressed otherwise, the operation simply comprises a casing that iB extended into a portion of the formation Prom a wellhead with a ~econd casing extending into the formation further as a wellbore is deepened to form an annulus which may include washouts or void areas behind the casing. The casing is adapted to be in commun~cation with the pump ~or circulating drilling Pluid through the interior of the casing, up the annulu~ and through a return conduit to a storage tank ~J~7,~ J1~,7~
or pit and is recirculated khrough the pump in normal drilling operations. Conventional drilling fluid conditioning devices such as shale shakers, sand separators and related equipment may be employed; but are normally not shown in schematic illustrations in the interest o~ clarity. One method for converting a drilling fluid into a cementitious slurry is the addition o~ premixed quantities from storage of dry blended cement formulation for conduction to a slurry mixing operation. The ~ormulation is added ~o a slurry and mixe~ into the drilling fluid which is thereby converted into a cementitious slurry. It is at this point that it is convenient to add accelerators or the like to at least neutralize the 6et retarding effects of the varlous dispersants that may have ~een present in the drilling fluid, or added to the drilling fluid in the cement conversion process.
As described hereinbefore, compatible accelerators comprise the materials which will yield the formate ions without the violent reaction. We know ~rom experimental data that for~amide will provide excellent results and that th~ ~lrst ~our carbon esters oE formic acid will provide qood result~.
These material~ ar~ di~cussed in Haakh'3 Chemical Dictionary and do not re~uire ~urther description herein.
In thia invention, a compatible accelerator is employed when a concentration range of from 0.05 to about 2.5 gallons per ~arrel of original drilling fluid is present. A better concentration is a range of 0.3 -1.2 gallons per ~arrel of cement ~lurry employed7 The concentration may vary from this for a specific application. For most applications khe optimum concentration is about 0.6 gallons per barrel of cement slurry. This will result of a setting time for the cementitiou3 slurry of approximately twenty-~our hours, which is substantially ~horter than the prior art retarded cements.
When employed in an over wash, the compatible accelerator is in a concentration within the range of 5 percent by weight to 100 percent by weight, the remaindert if any, being water.
As indicated, this invention is useful also when an over wash is employed a~ter squeezing cement through perforations or in casing cracks. A highly retarded cement may be emplaced and then wa~hed over with a solution containing the compatible accelerator; for example, the first four carbon esters of formic acid.
The differential pressure extended from the wellbore into the formation will ~orce the liquid that is employed as the over wash solution containing the cement accelerator into the permeable cement matrix.
Normally, such an over pressure i~ ln the range of from 200 500 pound~ per 6quare inch ( psi) greater in the well than it i5 in the form~tion so it tends to e~fect flushing of the over wa~h solution containing the ce~ent accelerator through t~e hydrating cement matrix.
The compatible accelerator can be employed to mitigate adverse e~ect~ of contamlnation ~rom in situ mixing with ~luids, ~uch as drilling ~luids, in any application. Speciiically, i~ too much ret~rder is pu~
into a cement slurry, an e~ective amount of compatible accelerator can be employed to neutralize the retarder and get it back into the desired range.
In another operation, the ~olution containing the accelerator may be 6potted below a cement to be placed in a well ~o form a plug. Thereafter a spot of liquid containing the cement accel~rator may be positioned above the cement. A ~urfactant may be employed in a small concentration o~ about 0.1 ~1.0 percent (~), if des~red, in th~ preflush~ cement ~lurry, or overflush, l~ /S;
to decrease the interfacial tension and help the surrounding fluids to penetrate into the cement matrix.
The accelerators have the property o~ accelerating the set o~ the cement and have the potential for immediate application in the conversion of mud to cement and as an over wash additive, or Por washing an acceleratiny solution from both above and/or below to produce acceleration of cement nodes in remedial squeeze operations, cement plugs in plugback, kicko~f, whipstock procedures, or cement at the top of liners after liner cementing operations.
EXAMPLE
The ~ollowing example illustrates both a control without this invention and laboratory experiments performed to ~imulate field conditions and show e~fectiveness o~ the accelerator.
EXAMPL~ I
Xn thls exampl~ from 350 cubic c:entimet~ri (cc's), serving as an experimental one barrel quantlty, o~
10.45 pounds (lb~.) per gallon (ppg) Rapid Mud (a trademark o~ Baroid Corp) wa~ employed with 175 cc's serving as 0.5 barrel of water, and 300 lbs. per barrel (coarse grind) Raiser Cement in a quant~ty of 300 grams was employed wikh 2.25 lbs. per barrel (2.25 gram SSMA, which is ~ul~onated styrene ~aleic anhydride copolymer). The result was a retarded cement having a density o~ 12.3 pounds per gallon. This served as a base ~or comparison and had 0 psi compressive strength and had not even begun to ~et up after 4 days, but after 4.6 day~ it gave a compressive strength o~ 50 psi and a~ter 11 day~ gave a compressive strength of 500 ``` ~,;~i i"! ,/1 psi but the pumping time was still about 48~ hours at 94 degrees Fahrenheit.
In contrast, 350 cc's of 10.45 ppg Rapid Mud in 175 cc's water, giving 300 lbs. per barrel ~coarse grind) Xaiser Cement with 3 gms. (lbs. per barrel) SSMA
and 2.4 gal/bbl, or 20 ml., of formamide, gave a compressive strength of 50 psi ~pounds per square inch) after only 18 hours; 460 psi after 4 days and 562 psi after 11 day~. The pumping time remained unchanged at 48+ hours at 94 degrees Fahrenheit.
Although this invention has been described with a certain degree of particularity, it is understood that the present di~closure i8 made only by way of example and that numerous changes in the details of ; construction and the combination and arrangement of part~ may be resorted to without departing fro~ the spirit and the scope of the invention, re~erence being had for the latter purpose to the appended claims.
Claims (15)
1. A cement composition for cementing a space in a wellbore penetrating an earth formation wherein said space in said wellbore is occupied by a drilling fluid, said composition comprising:
a. a quantity of said drilling fluid;
b. a dry cement material c. a dispersant in an effective amount; and d. a compatible accelerator selected from a group consisting of a material that will provide formate ions without violent reaction with basic cement slurry constituents.
a. a quantity of said drilling fluid;
b. a dry cement material c. a dispersant in an effective amount; and d. a compatible accelerator selected from a group consisting of a material that will provide formate ions without violent reaction with basic cement slurry constituents.
2. The composition set forth in claim 1 wherein said drilling fluid has a density of about 9.0 pounds per gallon (ppg) to about 18.0 ppg and said accelerator is provided in a proportion within the range of 0.05-2.5 gallons per barrel of drilling fluid to be set to cement.
3. The composition set forth in claim 2 wherein said cement material comprises Portland cement.
4. The composition set forth in claim 3 wherein said Portland cement is provided in a concentration of about 100 pounds per barrel (ppb) to about 600 ppb.
5. In a method of setting a volume of cement in a well completed in a subterranean formation in which a cement is or may become retarded and is pumped into said well and allowed to set to form a hard cementitious material therewithin, the improvement comprising:
contacting said cement with a solution of compatible organic accelerator comprising material that will produce formate ions in the cement slurry and selected from the group consisting of the first four carbon esters of formic acid, said esters including methyl formate, ethyl formate, normal-propyl formate, iso-propyl formate, normal-butyl formate, iso-butyl formate, and t-butyl formate.
contacting said cement with a solution of compatible organic accelerator comprising material that will produce formate ions in the cement slurry and selected from the group consisting of the first four carbon esters of formic acid, said esters including methyl formate, ethyl formate, normal-propyl formate, iso-propyl formate, normal-butyl formate, iso-butyl formate, and t-butyl formate.
6. The method of claim 5 wherein said compatible organic accelerator is the methyl formate which is present in a concentration in the range of 0.5 - 2.5 gallons per barrel based on the original drilling fluid present.
7. The method of claim 5 wherein said compatible organic accelerator is the ethyl formate, which is present in a concentration in the range of 0.5 - 2.5 gallons per barrel based on the original drilling fluid present.
8. The method of claim 5 wherein said compatible organic accelerator is the iso-propyl formate which is present in a concentration in the range of 0.5 - 2.5 gallons per barrel based on the original drilling fluid present.
9. The method of claim 5 wherein said compatible organic accelerator is the normal-propyl formate which is present in a concentration in the range of 0.5 - 2.5 gallons per barrel based on the original drilling fluid present.
10. The method of claim 5 wherein said compatible organic accelerator is the iso-butyl formate which is present in concentration in the range of 0.5 - 2.5 gallons per barrel based on the original drilling fluid present.
11. The method of claim 5 wherein said compatible organic accelerator is the normal-butyl formate which is present in a concentration in the range of 0.5 - 2.5 gallons per barrel based on the original drilling fluid present.
12. The method of claim 5 wherein said compatible organic accelerator is the t-butyl formate which is present in a concentration in the range of 0.5 - 2.5 gallons per barrel based on the original drilling fluid present.
13. In a method of setting a volume of cement in a well completed in subterranean formation, in which a cement is or may become retarded and is pumped into said well and allowed to set to form hard cementitious material therewithin at liner tops and in wellbore plugs, the improvement comprising:
contacting downhole said cement with a solution of a compatible organic accelerator comprising a material that will produce formate ions in the cement slurry and selected from the group consisting of formamide, and esters of formic acid, said esters including methyl formate, ethyl formate, normal propyl formate, isopropyl formate, normal butyl formate, iso butyl formate and t-butyl formate.
contacting downhole said cement with a solution of a compatible organic accelerator comprising a material that will produce formate ions in the cement slurry and selected from the group consisting of formamide, and esters of formic acid, said esters including methyl formate, ethyl formate, normal propyl formate, isopropyl formate, normal butyl formate, iso butyl formate and t-butyl formate.
14. The method of claim 13 wherein said compatible organic accelerator is formamide and said formamide is employed in a step of overwashing a retarded cement composition with an overwash fluid; said formamide comprising from 5 to 100 percent by weight of said overwash fluid.
15. The method of claim 13 wherein said compatible organic accelerator is an ester of formic acid and said formic acid ester is employed in a step of overwashing the retarded cement composition with a compatible accelerator that will decrease the setting time for the cement, the fluid being called an overwash fluid, said formic acid ester comprising from 5 to 100 percent by weight of said overwash fluid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/552,238 US5005646A (en) | 1989-08-14 | 1990-07-12 | Accelerating set of retarded cement |
| US07/552,238 | 1990-07-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2046714A1 true CA2046714A1 (en) | 1992-01-13 |
Family
ID=24204479
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002046714A Abandoned CA2046714A1 (en) | 1990-07-12 | 1991-07-10 | Accelerating set of retarded cement |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2046714A1 (en) |
-
1991
- 1991-07-10 CA CA002046714A patent/CA2046714A1/en not_active Abandoned
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5005646A (en) | Accelerating set of retarded cement | |
| US9957434B2 (en) | Cementitious compositions comprising a non-aqueous fluid and an alkali-activated material | |
| US5082499A (en) | Well preflush fluid | |
| US5305831A (en) | Blast furnace slag transition fluid | |
| US5213160A (en) | Method for conversion of oil-base mud to oil mud-cement | |
| US5382290A (en) | Conversion of oil-base mud to oil mud-cement | |
| US5476144A (en) | Conversion of oil-base mud to oil mud-cement | |
| US3557876A (en) | Method and composition for drilling and cementing of wells | |
| US5585333A (en) | Hydrocarbon base cementitious drilling fluids and methods | |
| US3168139A (en) | Converting drilling muds to slurries suitable for cementing oil and gas wells | |
| US6668929B2 (en) | Methods and oil-based settable spotting fluid compositions for cementing wells | |
| US6716282B2 (en) | Methods and oil-based settable spotting fluid compositions for cementing wells | |
| US4547298A (en) | Drilling mud composition which may be converted to cement upon irradiation | |
| US6666268B2 (en) | Methods and oil-based settable drilling fluid compositions for drilling and cementing wells | |
| US4760882A (en) | Method for primary cementing a well with a drilling mud which may be converted to cement using chemical initiators with or without additional irradiation | |
| US4768593A (en) | Method for primary cementing a well using a drilling mud composition which may be converted to cement upon irradiation | |
| US4691774A (en) | Novel ferrofluids for use in cementing wells | |
| US3887009A (en) | Drilling mud-cement compositions for well cementing operations | |
| US5464060A (en) | Universal fluids for drilling and cementing wells | |
| US4463808A (en) | Method for effecting seals in earth boreholes | |
| US3724564A (en) | Technique for controlling lost circulation | |
| US3799874A (en) | Well cementing | |
| US5076852A (en) | Cementing oil and gas wells | |
| US3022824A (en) | Method and composition for cementing wells | |
| CA2560553C (en) | Methods of making cement compositions using liquid additives containing lightweight beads |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20020710 |