U.S. patent application number 17/191229 was filed with the patent office on 2021-06-24 for cement slurry compositions responsive to hydrocarbon gas.
This patent application is currently assigned to Saudi Arabian Oil Company. The applicant listed for this patent is Saudi Arabian Oil Company. Invention is credited to Mahmoud Alqurashi, Herschel Foster, Shrikant Tiwari.
Application Number | 20210189217 17/191229 |
Document ID | / |
Family ID | 1000005432878 |
Filed Date | 2021-06-24 |
United States Patent
Application |
20210189217 |
Kind Code |
A1 |
Foster; Herschel ; et
al. |
June 24, 2021 |
CEMENT SLURRY COMPOSITIONS RESPONSIVE TO HYDROCARBON GAS
Abstract
Methods and compositions for reducing gas seepage into a cement
slurry. One method includes adding a formulation to the cement
slurry, the formulation comprising at least one component
responsive to a predetermined concentration of hydrocarbon gas in
the cement slurry, where upon the cement slurry reaching the
predetermined concentration of hydrocarbon gas, the hydrocarbon gas
undergoes at least a partial oxidation caused by the formulation to
quicken the setting time of the cement slurry via release of heat
by an exothermic reaction.
Inventors: |
Foster; Herschel; (Dhahran,
SA) ; Alqurashi; Mahmoud; (Dhahran, SA) ;
Tiwari; Shrikant; (Dhahran, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Saudi Arabian Oil Company |
Dhahran |
|
SA |
|
|
Assignee: |
Saudi Arabian Oil Company
Dhahran
SA
|
Family ID: |
1000005432878 |
Appl. No.: |
17/191229 |
Filed: |
March 3, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16104084 |
Aug 16, 2018 |
|
|
|
17191229 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 2208/10 20130101;
C09K 8/493 20130101 |
International
Class: |
C09K 8/493 20060101
C09K008/493 |
Claims
1. A composition for reducing gas seepage into a cement slurry, the
composition comprising: at least one component responsive to a
predetermined concentration of hydrocarbon gas in the cement
slurry, where upon the cement slurry reaching the predetermined
concentration of hydrocarbon gas, the hydrocarbon gas undergoes at
least a partial oxidation caused by the composition to quicken the
setting time of the cement slurry via release of heat by an
exothermic reaction.
2. The composition according to claim 1, where the composition
includes an oxidant and a catalyst.
3. The composition according to claim 2, where the oxidant
comprises hydrogen peroxide.
4. The composition according to claim 3, where the catalyst is
selected from the group consisting of: a metal-containing
heterogeneous catalyst; a metal-containing homogeneous catalyst;
and combinations thereof.
5. The composition according to claim 4, where the metal comprises
a metal selected from the group consisting of: gold; palladium;
platinum; copper; iron; molybdenum; tin; rhodium; ruthenium; and
combinations of the same.
6. The composition according to claim 5, where the composition
further comprises a strong acid.
7. The composition according to claim 4, comprising the
metal-containing heterogeneous catalyst, where the heterogeneous
catalyst includes supported nanoparticles.
8. The composition according to claim 2, where at least one
component is encapsulated.
9. The composition according to claim 1, where the at least one
component comprises between about 1% by weight and about 6% by
weight of the cement slurry.
Description
PRIORITY
[0001] This application is a non-provisional divisional application
of and claims priority to and the benefit of U.S. application Ser.
No. 16/104,084, filed on Aug. 16, 2018, the entire disclosure of
which is incorporated here by reference.
BACKGROUND
Field
[0002] Embodiments of the disclosure relate to cement slurries
responsive to hydrocarbon gas concentrations. In particular,
embodiments of the disclosure show cement slurry compositions with
quickened setting times in response to exposure to certain levels
of hydrocarbon gas, for example methane in a hydrocarbon-bearing
reservoir.
Description of the Related Art
[0003] Cementing is applied in oil and gas drilling to stabilize
wells and can be used, for example, with casings. Well design
typically includes several casing strings. A predetermined size of
hole is drilled to a casing point, and casing is run to avoid
collapse of the drilled formation. Casing strings are cemented in
place to ensure proper isolation from deeper formations to be
drilled, and further to fulfil well objectives.
[0004] During oil and gas well cementing operations, there may be
an influx of gas into wet cement slurry once disposed in a
wellbore. This occurs during cement slurry transitions, as the
cement slurry loses its hydrostatic weight and prior to thickening.
Keeping the transition time between the slurry phase and hardened
cement as short as possible is important to minimize gas influx and
gas migration up the hole through channels. In the oil and gas
industry, this is sometimes referred to as right angle set.
[0005] In shallow wells, proper cement setting profiles are
difficult to produce due to lower temperatures of the shallow wells
(longer set times) and lesser amount and weight of slurry required.
Also in some areas, there is significant shallow gas accumulation,
which makes effective cementing extremely difficult. Once gas
enters the annulus surrounding the wellbore with setting cement,
the gas will rise to the surface creating a path or channel as it
progresses through the setting cement, which is undesirable.
Certain gas intrusion and gas channel formation mitigation methods
and compositions exist and are used in the oil and gas industry,
but rely on expanding agents (inert gas generating agents) or latex
compounds in order to prevent the formation of gas channels.
Existing mitigation compositions and methods can negatively impact
wellbore cementing operations and lack effectiveness.
[0006] Poor cementation can significantly impact subsequent well
performance and return on investment. In comparison to the initial
expenditure, a poor cement job can result in very high remedial
costs. For example, failure to achieve good zonal isolation in
primary cementing costs millions of dollars each year in well
repairs and lost production.
SUMMARY
[0007] Applicant has recognized that there is a need for responsive
cement slurry compositions, methods, and systems for enhancing
cement setting ability in the presence of external damaging
components, for example natural gas comprising methane. In some
embodiments, compositions of the present disclosure are responsive
to or react to a certain level of gas intrusion into a cement
slurry and react only at or above a certain level of gas intrusion.
Gas channel mitigation is effected once the cement slurry is in
place and setting, for example in a wellbore proximate well
casing.
[0008] In the event of hydrocarbon gas intrusion, for example
methane or ethane, in concentrations above a predetermined
threshold coming in contact with a cement slurry in static
condition, compositions of the present disclosure will effect an
exothermic reaction. The compositions can be incorporated into the
cement slurry without lessening the final set strength of the
cement.
[0009] Exothermic reactions of the present disclosure accelerate
cement slurry transition profiles from slurry to solid, reducing
the time required between hydrostatic head loss and cement setting
thereby preventing more gas, for example methane, from entering the
wellbore, penetrating the cement matrix, or migrating further up
the wellbore toward the surface. Embodiments of the present
disclosure reduce or eliminate problems related to channeling in
cement matrices, which can include a breach of the annular barrier
generally resulting in migration of fluid influx past the cement
barrier causing casing to casing annulus (CCA) pressures throughout
the life of the well.
[0010] Embodiments of the disclosure add one or more reagent to
well cement slurry, which is responsive to the presence of free
hydrocarbon gas and acts as an initiator and/or catalyst to carry
out an exothermic reaction. For example, once a required volume of
cement slurry is pumped into a wellbore and is in static condition,
in an annulus for example, methane gas concentration above a
certain threshold proximate and/or within the cement slurry will
activate the one or more reagent to start an exothermic reaction.
This exothermic reaction generates heat, which will change the
setting profile of the slurry and greatly reduce the transition
time between the slurry and solid states. Embodiments of the
present disclosure allow cement setting at a right angle profile,
thereby trapping hydrocarbon gas before it has a chance to complete
its migration to the surface forming vertical flow channels within
the cement.
[0011] Certain compositions and methods of the present disclosure
do not depend or rely on formation temperature, as example
reactions can depend on gas concentration only, thereby allowing
gas channel mitigation techniques described here to be used in
wells at a variety of temperatures.
[0012] Example embodiments of compositions, methods, and systems
described herein utilize exothermic chemical reactions based on the
controlled oxidation of naturally occurring hydrocarbon gases, for
example methane, in the formation to methanol, carbon dioxide,
water, and heat. Suitable exothermic reactions can occur when
methane reacts with an oxidative agent, such as for example
hydrogen peroxide in addition to or alternative to a similar
oxidant. Such oxidants can be pre-mixed into suitable reactive
compositions and into the cement slurry, or can be generated in
situ.
[0013] Therefore, disclosed herein is a method for reducing gas
seepage into a cement slurry, the method comprising the steps of
adding a formulation to the cement slurry, the formulation
comprising at least one component responsive to a predetermined
concentration of hydrocarbon gas in the cement slurry, where upon
the cement slurry reaching the predetermined concentration of
hydrocarbon gas, the hydrocarbon gas undergoes at least a partial
oxidation caused by the formulation to quicken the setting time of
the cement slurry via release of heat by an exothermic reaction. In
some embodiments of the method, the formulation includes an oxidant
and a catalyst. In other embodiments of the method, the oxidant
comprises hydrogen peroxide. Still in other embodiments, the
catalyst is selected from the group consisting of: a
metal-containing heterogeneous catalyst; a metal-containing
homogeneous catalyst; and combinations thereof.
[0014] In certain embodiments, the formulation further comprises a
strong acid. In yet other embodiments, the method includes the step
of injecting the cement slurry into an annulus proximate a
wellbore. In some embodiments, the method includes the step of
adding the formulation to the annulus via a spacer fluid before
injecting the cement slurry. Still in other embodiments, the step
of adding the formulation is performed after the step of injecting
the cement slurry. In certain embodiments, the step of adding the
formulation is performed during the step of injecting the cement
slurry. Some embodiments of the method include the step of
generating hydrogen peroxide in situ proximate the wellbore. In
other embodiments, the formulation comprises between about 1% by
weight and about 6% by weight of the cement slurry.
[0015] Additionally disclosed is a composition for reducing gas
seepage into a cement slurry, the composition including at least
one component responsive to a predetermined concentration of
hydrocarbon gas in the cement slurry, where upon the cement slurry
reaching the predetermined concentration of hydrocarbon gas, the
hydrocarbon gas undergoes at least a partial oxidation caused by
the composition to quicken the setting time of the cement slurry
via release of heat by an exothermic reaction. In some embodiments,
the composition includes an oxidant and a catalyst. In other
embodiments, the oxidant comprises hydrogen peroxide. Still in
other embodiments, the catalyst is selected from the group
consisting of: a metal-containing heterogeneous catalyst; a
metal-containing homogeneous catalyst; and combinations
thereof.
[0016] In certain embodiments, the metal comprises a metal selected
from the group consisting of: gold; palladium; platinum; copper;
iron; molybdenum; tin; rhodium; ruthenium; and combinations of the
same. In yet still other embodiments of the composition, the
composition further comprises a strong acid. In certain
embodiments, the heterogeneous catalyst includes supported
nanoparticles. In some embodiments, at least one component is
encapsulated. And still in other embodiments, the at least one
component comprises between about 1% by weight and about 6% by
weight of the cement slurry.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] These and other features, aspects, and advantages of the
present disclosure will become better understood with regard to the
following descriptions, claims, and accompanying drawings. It is to
be noted, however, that the drawings illustrate only several
embodiments of the disclosure and are therefore not to be
considered limiting of the disclosure's scope as it can admit to
other equally effective embodiments.
[0018] FIG. 1 is a cross-sectional diagram of a wellbore showing a
responsive cement slurry of the present disclosure disposed around
a casing before setting.
[0019] FIG. 2 is a cross-sectional diagram of a wellbore showing a
responsive cement slurry of the present disclosure disposed around
a casing once set, optionally having been exposed to a gas
penetrant from the formation as it set.
DETAILED DESCRIPTION
[0020] So that the manner in which the features and advantages of
the embodiments of cement slurry compositions, methods, and systems
for enhancing cement setting ability in the presence of external
damaging components, for example natural gas comprising methane, as
well as others, which will become apparent, may be understood in
more detail, a more particular description of the embodiments of
the present disclosure briefly summarized previously may be had by
reference to the various embodiments, which are illustrated in the
appended drawings, which form a part of this specification. It is
to be noted, however, that the drawings illustrate only various
embodiments of the disclosure and are therefore not to be
considered limiting of the present disclosure's scope, as it may
include other effective embodiments as well.
[0021] In embodiments of the disclosure, added to a wellbore cement
slurry is a composition including one or more reagent in addition
to or alternative to one or more catalyst, which allows an
exothermic reaction to take place once methane in addition to or
alternative to other hydrocarbon gas crosses a certain
concentration threshold as it enters the slurry in situ. The
composition can include one or more homogeneous or heterogeneous
catalyst. For example, a suitable exothermic reaction mechanism
includes the selective oxidation of hydrocarbons with hydrogen
peroxide in the presence of at least one low temperature
catalyst.
[0022] In industry today, certain catalytic oxidations are used for
the conversion of petroleum-derived hydrocarbons to commodities,
and catalytic oxidations are also used in the manufacture of fine
chemicals. An example chemical equation for one intended exothermic
chemical reaction is provided below in Equation 1. In other
embodiments, other reactants, products, and more than one catalyst
may exist for a given exothermic reaction.
H.sub.2O.sub.2+C.sub.nH.sub.n+CH.sub.4(g)+CATALYST.fwdarw.CH.sub.3OH+H.s-
ub.2O+CO.sub.2+HEAT Eq. 1
[0023] Methane, a large constituent of formation gas which can
enter a given wellbore, is a small and hard molecule, which is
generally difficult to react. A suitable catalyst in the cement
slurry acts in similar manner to a catalytic converter in an
automobile exhaust system. For example, materials used in the
slurry may be palladium-based catalysts, which have been found to
be efficient catalysts for the catalytic oxidation of methane to
carbon dioxide and water. Certain catalysts which provide
substantially complete CH.sub.4 oxidation at low temperatures are
usually based on noble metals (for example Pd, Pt, Rh, Ru). These
metals do not react with the cement slurry itself, and are inert in
the slurry's presence, including with H.sub.2O.sub.2, until the
metal comes into contact with a pre-determined or pre-selected
methane concentration at formation temperature.
[0024] Another catalytic formulation can include a platinized tin
oxide (Pt/SnOx), which can be used in addition to or alternative to
silica and cordierite catalyst supports. Originally developed for
removal of CO, this catalyst has also proven effective for removal
of lightweight hydrocarbons, such as methane.
[0025] Methane and higher molecular weight hydrocarbon
concentrations may be great or small, depending on the formation,
wellbore, and cement type. In the case of lesser concentrations of
methane in cement slurry, for example less than about 1% by weight
methane, less than about 5% by weight methane, less than about 10%
by weight methane or less than about 20% by weight methane, in some
embodiments there will be no significant impact on the quality of
the cement job. The amount of catalyst and any additional oxidizing
component, such as for example H.sub.2O.sub.2, is pre-determined or
pre-selected to react at a threshold amount of methane
concentration.
[0026] In the case of greater concentrations of methane which might
damage the integrity of the cement during setting in certain
wellbore design instances, for example in some embodiments greater
than about 1% by weight methane, greater than about 5% by weight
methane, greater than about 10% by weight methane, or greater than
about 20% by weight methane, the catalytic reaction would produce
proportionally more heat hence reducing the transition time of the
slurry. In some embodiments, cement additives other than the
catalyst(s) can comprise between about 0.5% by weight and about 10%
by weight or between about 1% by weight and about 5% by weight or
between about 1% by weight and about 3% by weight of the cement
slurry. In some embodiments, the catalyst(s) can comprise between
about 0.5% by weight and about 10% by weight or between about 1% by
weight and about 5% by weight or between about 1% by weight and
about 3% by weight of the cement slurry.
[0027] In the reaction with the hydrocarbon gas, one or more
catalyst speeds up the removal of the methane according to Equation
1 supra. Once again, suitable catalysts include those comprising
platinum or a similar element, which could be a platinum-like metal
such as palladium or rhodium. Also, an effective catalyst for the
oxidation of methane and higher hydrocarbons is Cr.sub.2O.sub.2.
These compounds and element candidates for catalysts can be similar
to those used in industrial tasks where oxidizing methane emissions
is required before release into the atmosphere.
[0028] As noted, the useful part of this process for oil well
cementing is that the reaction is highly exothermic. A localized
reaction, for example according to Equation 1, can in some
embodiments increase localized temperature by about 200.degree. F.
or by about 300.degree. F., and thereby increase cement setting
time. Other compounds can also be used in addition to or
alternative to noble metals, and certain examples are discussed
herein only for illustration purposes.
[0029] There are many other oxidation methods that can be used to
reach the same goal, such as for example the oxidation of n-alkanes
by cobaltic acetate activated by strong acids. This method allows
n-alkanes to be significantly oxidized at low temperature in an
exothermic reaction and does not depend on traditional addition of
accelerators to reduce slurry transition time.
[0030] Embodiments of the compositions and methods described are
unique, as the use of specifically tailored reagents or compounds,
such as for example one or more homogeneous or heterogeneous
catalyst and hydrogen peroxide, at specific concentrations allow
responsiveness to a predetermined concentration of hydrocarbon gas,
for example methane, leaking into the slurry. In the absence of a
predetermined threshold of hydrocarbon gas, cement slurries of the
present disclosure with gas-responsive compositions will behave as
any other standard design cement slurry.
[0031] For example, A review of the direct oxidation of methane to
methanol by Han, B., et al. discusses the state of certain
technology surrounding the direct oxidation of methane to methanol.
(Chinese Journal of Catalysis 37 (2016) 1206-1215). Both
homogeneous and heterogeneous catalysts are discussed, along with
strong acid systems. The direct oxidation of methane to methanol is
exothermic, but other reactions can occur in embodiments of the
present disclosure which are also exothermic. Water is discussed as
a viable medium for such reactions with H.sub.2O.sub.2 as an
oxidant, the oxidant being decomposed for example in the presence
of metals/metal ions for the catalytic oxidation of methane. Cement
slurries of the present disclosure include aqueous cement
slurries.
[0032] In Oxidation of Methane to Methanol with Hydrogen Peroxide
Using Supported Gold-Palladium Alloy Nanoparticles, Hasbi Ab Rahim,
M., et al. show Au--Pd supported nanoparticles are suitable for the
oxidation of methane to methanol, which can be done using hydrogen
peroxide generated in situ from hydrogen and oxygen. (Angew. Chem.
Int. Ed. 2013, 52, 1280-1284). CuFe-ZSM-5 (Zeolite Socony Mobil-5)
can also be used as a catalyst for the conversion of methane to
methanol using H.sub.2O.sub.2. In some reactions, the oxidation of
methane to methanol is carried out in a liquid phase using water as
a solvent and H.sub.2O.sub.2 as an oxidant. The conversion of
methane to methanol can be carried out between about 30.degree. C.
and about 90.degree. C. (about 86.degree. F. to about 194.degree.
F.), and thus is suitable for use in hydrocarbon reservoirs and
wellbores. Particle sizes of heterogeneous catalyst can be in the
range of about 1 nanometer (nm) to about 200 nm, in some
embodiments. Suitable temperatures for the reaction to be carried
out include temperatures up to about 200.degree. F. in some
embodiments, and up to about 300.degree. F. in other
embodiments.
[0033] In some embodiments of Equation 1, the catalyst includes
supported gold-palladium with tin [Pd--Au/TiO2/Sn], where Sn or
other catalytic nanoparticles facilitate the oxidation of methane,
producing methyl hydroperoxide (CH.sub.4O.sub.2) and methanol,
using hydrogen peroxide as the oxidant. Methanol selectivity is
achieved by performing the reaction in the presence of hydrogen
peroxide. In oil well applications, the hydrogen peroxide can be
added to the slurry in powdered form as sodium percarbonate
(Na.sub.2H.sub.3CO.sub.6).
[0034] In Selective Low Temperature Oxidation of Methane with
Hydrogen Peroxide by Quasi-Heterogeneous Catalysis, McVicker, R.
discusses methane oxidation to methanol at low temperatures
(<250.degree. C.) is effective over high valent transition metal
electrophiles. (Cardiff Catalysis Institute 2014). For example, a
highly acidic homogeneous catalysis system comprising oleum
achieved oxidation of methane to methanol using aqueous
chloroplatinum complexes. Other low temperature heterogeneous
systems are discussed, for example including platinum.
[0035] In Reaction Mechanism of Oxidation of Methane with Hydrogen
Peroxide Catalyzed by 11-Molybdo-1-vanadophosphoric Acid Catalyst
Precursor, Seki, Y., et al. discuss vanadium-containing catalysts
for the liquid-phase oxidation of methane with hydrogen peroxide.
(J. Phys. Chem. B 2000, 104, 5940-5944). As noted previously,
low-temperature oxidation of n-alkanes can also be achieved by
cobaltic acetate activated by strong acids. For example, Hanotier,
J., et al. in Low-temperature oxidation of n-alkanes by cobaltic
acetate activated by strong acids discuss strong organic or
inorganic acids enhancing the oxidizing activity of cobaltic
acetate in acetic acid for n-alkanes. (Journal of the Chemical
Society, Perkin Transactions 2 1972).
[0036] In embodiments of the present disclosure, homogeneous
catalysts comprising metals can be used in addition to or
alternative to heterogeneous catalysts comprising metals for the
oxidation of hydrocarbon gases, for example methane to methanol. In
embodiments of the present disclosure, hydrogen peroxide in
addition to or alternative to other oxidants can be added to cement
slurry or generated in situ in the wellbore proximate a hydrocarbon
bearing formation. Other radical species can be generated as needed
for the oxidation of hydrocarbons.
[0037] Referring now to FIG. 1, a cross-sectional diagram is shown
of a wellbore with a responsive cement slurry of the present
disclosure disposed around a casing before setting. In wellbore
system 100, a casing 102 in a first annulus is surrounded by a
fluid cement slurry 104, for example aqueous cement slurry, in a
second annulus surrounding production tubing 106. A hydrocarbon
gas-responsive composition 108 is disposed within and suspended
amongst fluid cement slurry 104.
[0038] In some embodiments, a hydrocarbon gas-responsive
composition is mixed with a cement slurry at the surface. In other
embodiments, a hydrocarbon gas-responsive composition is mixed with
the cement slurry during injection of the cement slurry and/or once
the cement slurry is disposed in an annulus and is static. In other
embodiments, a hydrocarbon gas-responsive composition can be placed
into an annulus before placement of a cement slurry, for example
via injection of a spacer fluid comprising a hydrocarbon
gas-responsive composition between use of an oil-based and/or
water-based mud and the use of a cement slurry in an annulus.
[0039] Hydrocarbon gas-responsive composition 108 can comprise, for
example, metal catalyst, either or both heterogeneous or
homogeneous, hydrogen peroxide in addition to or alternative to
other oxidants, and optionally other reagents to effect the
oxidation of n-alkanes, such as methane. Components of hydrocarbon
gas-responsive composition 108 may be encapsulated for protection
from the cement slurry or for delayed release over time into the
cement slurry. Hydrocarbon gas seepage points 110 allow hydrocarbon
gases to seep into fluid cement slurry 104 from a shallow gas zone,
a gas reservoir, and/or a gas cap zone, for example, in
hydrocarbon-bearing formation 112. Natural gas, for example
comprising methane, may seep into a slurry from other portions of a
hydrocarbon-bearing reservoir.
[0040] Referring now to FIG. 2, a cross-sectional diagram is shown
of a wellbore with a set responsive cement slurry of the present
disclosure disposed around a casing, optionally having been exposed
to a gas penetrant from the formation as it set. In wellbore system
200, a casing 202 in a first annulus is surrounded by a set cement
slurry 204 in a second annulus surrounding production tubing 206.
In one example, set cement slurry 204 sets faster with hydrocarbon
gas-responsive composition 108 from FIG. 1 when a hydrocarbon gas
level, for example methane, within fluid cement slurry 104 reaches
a predetermined level to trigger an oxidation reaction with
hydrocarbon gas-responsive composition 108. This results in an
exothermic reaction, for example the oxidation of methane to
methanol, causing fluid cement slurry 104 to set to set cement
slurry 204. Set cement slurry 204 supports casing 202 while also
preventing the seepage of more hydrocarbon gas into set cement
slurry 204.
[0041] The present systems, methods, and compositions are
applicable to drilling and workover operations in all areas with
drilling and cementing across formations with expected shallow gas
zones, gas cap reservoirs, or gas reservoirs that would channel
through the annulus before cement slurry sets. Embodiments provide
for reduction and prevention of gas migrating into the wellbore.
The quality of the set cement is enhanced for the total life of the
well, as gas channels are reduced or eliminated. Unique additives
to cement slurry will only activate if predetermined conditions of
gas influx are met in static slurry conditions after a planned
volume of cement slurry has been pumped into a wellbore annulus.
Compositions of the present disclosure can remain inert, or not
oxidize or cause any exothermic reaction if the concentration of
gas is below the predetermined level.
[0042] Oxidation reactions of the present disclosure can proceed at
a variety of temperatures. The compositions, once reacted with
methane for example, will not affect the strength of the final set
cement. Embodiments of the present disclosure eliminate or reduce
the occurrence of CCA leaks, which is a common occurrence in
cementing operations where a gas influx occurs. The operations
typically take 1 to 2 weeks of rig time to remediate. This downtime
may now be reduced or eliminated.
[0043] Embodiments of the disclosure can also improve zonal
isolation of gas bearing zones which will increase reservoir
productivity. Underground communication can be eliminated or
reduced. Well cementing is critical in the construction,
completion, and abandonment of wells. The cement performs vital
functions in supporting the casing and wellhead equipment. The
casing cannot perform the functions it is designed for unless it is
effectively cemented in place. The cement also forms an impermeable
barrier to the passage of gases and fluids and enables formations
to be isolated once set.
[0044] Another advantage of the present application is well
integrity. Embodiments of the hydrocarbon gas-responsive
compositions allow proper isolation and bonding between pipe cement
and formations, thereby extending the life of the well before any
intervention is required for repair. Reduction and elimination of
gas channeling also increases safety for surface personnel during
drilling and workover operations, as there is less risk of gas
release at the surface. Surface equipment exposure to gas is also
reduced or eliminated.
[0045] The singular forms "a," "an," and "the" include plural
referents, unless the context clearly dictates otherwise.
[0046] In the drawings and specification, there have been disclosed
embodiments of compositions, systems, and methods for reducing gas
seepage into setting wellbore cement slurries, as well as others,
and although specific terms are employed, the terms are used in a
descriptive sense only and not for purposes of limitation. The
embodiments of the present disclosure have been described in
considerable detail with specific reference to these illustrated
embodiments. It will be apparent, however, that various
modifications and changes can be made within the spirit and scope
of the disclosure as described in the foregoing specification, and
such modifications and changes are to be considered equivalents and
part of this disclosure.
* * * * *