COMPOSITIONS COMPRISING QUATERNARY MATERIAL AND SOREL
CEMENTS AND METHODS OF SERVICING A WELLBORE WITH THE SAME
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present disclosure generally relates to wellbore servicing fluids, and more
particularly to viscosified Sorel cements and methods of using same.
Background of the Invention
[0002] Natural resources such as gas, oil, and water residing in a subterranean formation or
zone are usually recovered by drilling a wellbore down to the subterranean formation while
circulating a drilling fluid in the wellbore. After terminating the circulation of the drilling fluid,
a string of pipe, e.g., casing, is run in the wellbore. The drilling fluid is then usually circulated
downward through the interior of the pipe and upward through the annulus, which is located
between the exterior of the pipe and the walls of the wellbore. Next, primary cementing is
typically performed whereby a cement slurry is placed in the annulus and permitted to set into a
hard mass (i.e., sheath) to thereby attach the string of pipe to the walls of the wellbore and seal
the annulus. The main objectives of primary cementing operations include zonal isolation to
prevent migration of fluids in the annulus, support for the casing or liner string, and protection
of the casing string from corrosive formation fluids. Subsequent secondary cementing
operations may also be performed. Secondary or remedial cementing operations are performed
to repair primary-cementing problems or to treat conditions arising after the wellbore has been
constructed.
[0003] Oil or gas residing in the subterranean formation may be recovered by driving fluid
into the well using, for example, a pressure gradient that exists between the formation and the
wellbore, the force of gravity, displacement of the fluid using a pump or the force of another

fluid injected into the well or an adjacent well. The production of fluid in the formation may be
increased by hydraulically fracturing the formation. That is, a viscous fracturing fluid may be
pumped down the casing to the formation at a rate and a pressure sufficient to form fractures
mat extend into the formation, providing additional pathways through which the oil or gas can
flow to the well. Unfortunately, water rather than oil or gas may eventually be produced by the
formation through the fractures therein. To provide for the production of more oil or gas, a
fracturing fluid may again be pumped into the formation to form additional fractures therein.
However, the previously used fractures first may need to be plugged to prevent the loss of the
fracturing fluid into the formation via those fractures.
[0004] In addition to the fracturing fluid, other fluids used in servicing a wellbore may also
be lost to the subterranean formation while circulating the fluids in the wellbore. In particular,
the fluids may enter the subterranean formation via depleted zones, zones of relatively low
pressure, lost circulation zones having naturally occurring fractures, weak zones having fracture
gradients exceeded by the hydrostatic pressure of the drilling fluid, and so forth. As a result,
the service provided by such fluid is more difficult to achieve. For example, a drilling fluid
may be lost to the formation, resulting in the circulation of the fluid in the wellbore being too
low to allow for further drilling of the wellbore. Also, a secondary cement/sealant composition
may be lost to the formation as it is being placed in the wellbore, thereby rendering the
secondary operation ineffective in mamtaining isolation of the formation.
[0005] Lost circulation treatments involving various plugging materials such as walnut
hulls, mica and cellophane have been used to prevent or lessen the loss of fluids from
wellbores. The disadvantages of such treatments include the potential for damage to
subterranean formations as a result of the inability to remove the plugging materials therefrom,
and the dislodgement of the plugging materials from highly permeable zones whereby fluid

losses subsequently resume. One technique for preventing lost circulation problems has been to
temporarily plug voids or permeable zones with Sorel cement compositions. Sorel cement
compositions typically comprise magnesium oxide and a chloride or phosphate salt which
together form for example magnesium oxychloride. Sorel cements can be removed with
minimal damage to subterranean zones or formations by dissolution in acids. One drawback to
the use of Sorel cements is that the incorporation of additives is difficult due to the relatively
low viscosity of the slurries. Accordingly, it would be desirable to develop Sorel cement
compositions with improved viscosities.
BRIEF SUMMARY OF SOME OF TEE PREFERRED EMBODIMENTS
[0006] In one aspect, the invention relates to a wellbore servicing composition comprising
a metal oxide, a soluble salt and a viscosifier wherein the viscosifier comprises a quaternary
amide, a quaternary amide ester, or combinations thereof.
[0007] In another aspect, the invention relates to a wellbore servicing composition
comprising magnesium oxide, a chloride or phosphate salt and a quaternary material.
[0008] In another aspect, the invention relates to a wellbore servicing composition
comprising magnesium oxide, magnesium chloride, and a quaternary material wherein the
quaternary material comprises a quaternary amide, a quaternary amide ester or combinations
thereof and wherein the quaternary material is present in an amount of from about 0.05 wt.% to
about 5 wt.% and a plot of the composition's plastic viscosity as a function of the amount of
quaternary material is about linear.
[0009] In another aspect, the invention relates to a method of servicing a wellbore in
contact with a subterranean formation comprising viscosifying a cement composition
comprising a metal oxide and a soluble salt, placing the viscosified cement composition in the
wellbore, and allowing the composition to set.

[0010] In another aspect, the invention relates to a method of cementing a wellbore
comprising preparing a cement composition comprising magnesium oxide, a chloride or
phosphate salt, and a quaternary material, placing the cementitious composition into the
•wellbore, and allowing the cementitious composition to set.
[0011] In another aspect, the invention relates to a method of viscosifying a Sorel cement
comprising contacting the cement composition with quaternary material.
[0012] The foregoing has outlined rather broadly the features and technical advantages of
the present invention in order that the detailed description of the invention that follows may be
better understood. Additional features and advantages of the invention will be described
hereinafter that form the subject of the claims of the invention. It should be appreciated by
those skilled in the art that the conception and the specific embodiments disclosed may be
readily utilized as a basis for modifying or designing other structures for carrying out the same
purposes of the present invention. It should also be realized by those skilled in the art that such
equivalent constructions do not depart from the spirit and scope of the invention as set forth in
the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a more complete understanding of the present disclosure and the advantages
thereof, reference is now made to the following brief description, taken in connection with the
accompanying drawings and detailed description:
[0014] Figure 1 is a graph of the yield point and plastic viscosity as a function of the
amount of quaternary material for the samples from Example 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Disclosed herein are wellbore servicing fluids comprising a Sorel cement and a
viscosifier and methods of using same. In various embodiments, Sorel cements comprise a

metal oxide such as magnesium oxide and a soluble salt such as a chloride or phosphate salt. A
discussion of various magnesia-based cements can be found in Lea's Chemistry of Cement and
Concrete by Peter Hewlett: Fourth Edition, pages 813-820: 1998: Elsevier Publishing which is
incorporated by reference herein. In an embodiment, the viscosifier comprises a quaternary
material. Each of the components of the wellbore servicing fluid will be described in more
detail later herein. Such fluids may be placed into a wellbore and allowed to set and form a
rigid mass having an appreciable compressive strength. In an embodiment, the addition of a
quaternary material of the type disclosed herein to a Sorel cement composition increases the
viscosity of the cement composition in comparison to a Sorel cement composition lacking said
quaternary material
(0016] In an embodiment, the Sorel cement comprises a metal oxide, alternatively an
alkaline earth metal oxide, alternatively magnesium oxide. In an embodiment, the Sorel
cement comprises MgO. MgO may be prepared by calcination of Mg(OH)2 as depicted in
Reaction 1:
[0017] The calcination of Mg(OH)2 results in what is commonly referred to as "burned"
MgO. Three basic grades of burned MgO are typically produced with the differences between
each grade related to the degree of reactivity remaining after being exposed to a range of high
temperatures. The original magnesium hydroxide particle is usually a large and loosely bonded
particle. Exposure to thermal degradation by calcination causes the Mg(OH)2 to alter its
structure so that the surface pores are slowly filled in while the particle edges become more
rounded. This results in MgO with varying degrees of crystallinity and consequently varying
degrees of reactivity. When the MgO is produced by calcining to temperatures ranging

"between 1500°C - 2000°C the MgO is referred to as "dead-bumed" since the majority of the
reactivity has been eliminated. Dead-bumed MgO has the highest degree of crystallinity of the
three grades of burned MgO. An example of a dead-burned MgO includes without limitation
THERMATEK™ HT additive which is commercially available from Halliburton Energy
Services. A second type of MgO produced by calcining at temperatures ranging from 1000°C -
1500°C is termed "hard-burned" and displays an intermediate crystallinity and reactivity when
compared to the other two grades of burned MgO. An example of a hard-burned MgO includes
without limitation THERMATEK™ LT additive which is commercially available from
Halliburton Energy Services. The third grade of MgO is produced by calcining at temperatures
ranging from 700°C - 1000°C and is termed "light-burned" or "caustic" magnesia. Light-burned
MgO is characterized by a high surface area, a low crystallinity and a high degree of reactivity
when compared to the other grades of burned MgO. In embodiments, the MgO for use in the
Sorel cement comprises hard-burned MgO, hght-burned MgO, dead-burned MgO or
combinations thereof.
[0018] In an embodiment, the Sorel cement comprises a soluble salt, alternatively a
chloride salt, a phosphate salt or combinations thereof. In an embodiment, the Sorel cement
comprises an alkaline earth metal chloride, for example magnesium chloride (MgCl)2 such as
magnesium chloride hexahydrate, MgCl2.6H2O. MgCl2.6H2O is well known and available
from a wide variety of sources. For example, a suitable MgCl2.6H2O for use in this disclosure
is C-TEK commercially available from Halliburton Energy Services.
[0019] In an embodiment, the Sorel cement is formed through contacting MgO with
MgCl2.6H2O in the presence of other components to be described in more detail later herein.
In such an embodiment, the Sorel cement may comprise MgO and MgCl2.6H2O present in a
ratio of from about 2:1 MgO: MgCl2.6H2O, alternatively from about 1.5:1 MgO: MgCl2.6H2O

and alternatively from about 1:1 MgO: MgCl2.6H2O. Examples of Sorel cements comprising
MgO (e.g., THERMATEK™ HT additive, THERMATEK™ LT additive) and MgCl2.6H2O
(e.g., C-TEK) include without limitation THERMATEK™ rigid setting fluids commercially
available from Halliburton Energy Services.
[0020] In another embodiment, the Sorel cement comprises a phosphate salt. In such an
embodiment, the Sorel cement may comprise MgO and a phosphate salt such as for example
potassium phosphate, sodium phosphate, ammonium phosphate or combinations thereof. In
such embodiments, the ratio of MgO:phosphate salt may be from about 1:4 alternatively from
about 1:3, alternatively from about 1:2, alternatively from about 1:1.
[0021] In an embodiment, the Sorel cement comprises a viscosifier. Hereafter a
composition comprising a Sorel cement and viscosifier will be referred to as a viscosified
cement composition (VCC). The viscosifier may comprise any material compatible with the
other components of the VCC and able to increase the viscosity of the VCC. Alternatively, the
viscosifier comprises a quaternary amide, a quaternary amide ester or combinations thereof. In
an embodiment, the viscosifier comprises an amidopropalkonium chloride with a chain length
of greater than about C12, alternatively greater than about C13, alternatively greater than about
C14. An example of a viscosifier suitable for use in this disclosure includes without limitation
stearamidopropalkonium chloride. In an embodiment, the viscosifier is present in an amount of
from about 0.05 wt.% to about 5 wt.% based on the total weight of the MgO (e.g.
THERMATEK™ HT, THERMATEK™ LT), alternatively from about 0.05 wt.% to about 0.5
wt.%, alternatively from about 0.05 wt.% to about 0.4 wt.%.
[0022] In an embodiment, the VCC may comprise a retarder or inhibitor. Inhibitors may
be used to adjust the time required for setting of the slurry. Such inhibitors may allow the
operator to control the set time of the composition based on the geothermal temperature at

which the composition will be used. Increasing the weight percentage of the inhibitor will
increase the time required for the composition to undergo the phase transition from a slurry to a
set mass with appreciable compressive strength. Inhibitors suitable for use in this disclosure
include without limitation sodium hexametaphosphate (technical grade granular), potassium
magnesium phosphate hexahydrate, potassium magnesium hexametaphosphate or combinations
thereof. An example of an inhibitor suitable for use in this disclosure is sodium
hexametaphosphate commercially available from Deepearth Solutions under the trademark R-
TEK.
10023] In an embodiment, the thickening time of the VCC may be adjusted through the use
of an inhibitor (e.g., sodium hexametaphosphate) such that the composition remains pumpable
during downhole placement before rapidly setting. The thickening time refers to the time
required for the cement composition to achieve 70 Bearden units of Consistency (Bc). At about
70 Be, the slurry undergoes a conversion from a pumpable fluid state to a non-pumpable paste.
Inhibitors may be present in the VCC in a range of from about 0.01% to about 10.0% by weight
of the MgO (e.g. THERMATEK™ HT, THERMATEK™ LT), alternatively from about 0.1%
to about 8%, alternatively from about 0.1% to about 6%.
[0024] The VCC may include a sufficient amount of water to form a pumpable slurry. The
water may be fresh water or salt water, e.g., an unsaturated aqueous salt solution or a saturated
aqueous salt solution such as brine or seawater. The water may be present in the amount from
about 10 to about 180 percent by weight of cement (bwoc) wherein the cement comprises both
the MgO and the soluble salt, alternatively from about 28 to about 60 percent by weight of
cement, alternatively from about 30 to about 70 percent.
[0025] In some embodiments, additives may be included in the VCC for improving or
changing the properties thereof. Examples of such additives include but are not limited to salts,

accelerants, fluid loss agents, weighting materials, dispersants, vitrified shale, zeolites (or other
Al-Si), formation conditioning agents, or combinations thereof. Other mechanical property
modifying additives, for example, carbon fibers, glass fibers, metal fibers, minerals fibers, and
the like can be added to further modify the mechanical properties. These additives may be
included singularly or in combination. Methods for introducing these additives and their
effective amounts are known to one of ordinary skill in the art.
[00261 The components of the VCC may be combined using any mixing device compatible
with the composition as known to one of ordinary skill in the art, for example a batch mixer or
recirculating mixer.
[0027] The VCC may be placed into a wellbore as a single stream and activated by
downhole conditions to form a set rigid mass. In such an embodiment, the VCC may be placed
downhole through the drill bit forming a composition that substantially eliminates the lost
circulation. In yet another embodiment, the VCC is formed downhole by the mixing of a first
steam comprising one or more VCC components such as for example MgO and chloride or
phosphate salt and a second stream comprising additional VCC components. Alternatively, the
VCC may be formed downhole by the mixing of a first stream comprising MgO and a second
steam comprising the chloride or phosphate salt, quaternary material and optional additives.
Methods for introducing compositions into a wellbore to seal subterranean zones are described
in U.S. Patent Nos. 5,913,364; 6,167,967; and 6,258,757, each of which is incorporated by
reference herein in its entirety.
[0028] The VCCs of this disclosure may display expanded and improved utility as wellbore
servicing fluids due to their increased viscosity. Such fluids may be capable of readily
suspending modifying additives that result in improvements in mechanical properties such as
for example compressive strength, density and tensile strength. Furthermore, a VCC

comprising a Sorel cement (e.g. THERMATEK™ rigid setting fluid) and a viscosifier of the
type disclosed herein may have an increased compatibility with oleaginous fluids such as for
example oil-based muds or synthetic based muds further expanding the potential utility and
application of these compositions.
[0029] The VCCs of this disclosure may develop an appreciable compressive strength
when placed downhole. Herein the compressive strength is defined as the capacity of a material
to withstand axially directed pushing forces. The maximum resistance of a material to an axial
force is determined in accordance with API Recommended Practices 10B, Twenty-Second
Edition, December 1997. Beyond the limit of the compressive strength, the material becomes
irreversibly deformed and no longer provides structural support and/or zonal isolation. The
compressive strength a cement formation attains is a function of both the cement maturity (or
cure time) and the temperature at which setting occurs. The cement maturity specifically refers
to the time the cement formulation is allowed to set.
[0030] In an embodiment, the VCC may develop a compressive strength of from about 50
psi to about 20,000 psi, alternatively from about 100 psi to about 10,000 psi, alternatively from
about 1000 psi to about 10,000 psi. The compressive strength of the VCC may develop in from
about 15 minutes to equal to or greater than about 24 hours, alternatively from about 20 minutes
to about 10 hours, alternatively from about 30 minutes to about 8 hours.
[0031] In some instances, the VCC may further comprise an oleaginous fluid. In an
embodiment, an oleaginous fluid may be present in the VCC in an amount of from about 5% to
about 100% by weight of cement (bwoc) wherein the cement comprises both the MgO and the
soluble salt (e.g., THERMATEK™ rigid setting fluid), alternatively from about 5% to about
80% bwoc, alternatively from about 5% to about 50% bwoc, alternatively less than about 50%
bwoc. As will be understood by one of ordinary skill in the art, the compressive strength that

such a composition develops is directly proportional to the amount of oleaginous fluid present in
the VCC. For example, increasing the amount of oleaginous fluid present in the VCC will
decrease the final compressive strength of the set composition. Consequently, the compressive
strength of a VCC further comprising an oleaginous fluid may be adjusted by varying the ratio
of oleaginous fluid to VCC. Such adjustments may be made by one of ordinary skill in the art.
[0032] The VCCs of this disclosure may have a density from about 4 lb/gallon (ppg) to
about 25 ppg, alternatively from about 12 ppg to about 17 ppg, alternatively from about 6 ppg
to about 14 ppg. Density reducing additives such as glass beads or foam and expanding
additives such as gas, suspension aids, defoamers and the like may be included in the VCC to
generate a lightweight cement slurry. Amounts of such density-reducing additives and methods
for their inclusion are known to one of ordinary skill in the art.
[0033] The VCCs of this disclosure exhibit a relatively constant viscosity for a period of
time after they are initially prepared and while they are being placed in their intended locations
in the wellbore, i.e., during the period when the slurry is in motion. Eventually, the cement
compositions quickly set such that the viscosity increases from about 35 Be to equal to or
higher than 70 Be in equal to or less than about 60 minutes, alternatively equal to or less than
about 50 minutes, alternatively equal to or less than about 40 minutes, alternatively equal to or
less than about 30 minutes, alternatively equal to or less than about 20 minutes, alternatively
equal to or less than about 10 minutes, alternatively equal to or less than about 1 minute. This
sudden jump in viscosity may be very desirable in preventing unwanted events such as gas or
water migration into the slurry because it indicates the quick formation of impermeable mass
from a gelled state after placement. This behavior is often referred to as "Right Angle Set" and
such cement compositions are called "Right Angle Set Cement Compositions" in reference to
the near right angle increase shown in a plot of viscosity as a function of time.

(0034] In embodiments wherein the VCC further comprises an oleaginous fluid, the
presence of an oleaginous fluid may result in the loss of right angle set.
10035] The VCCs of this disclosure may display a different rheology than similar
compositions lacking a viscosifier. Rheology refers to the deformation and flow of matter
under the influence of an applied stress. In an embodiment, the VCC is viscoelastic.
Viscoelastic refers to a time-dependent property in which a material under stress produces both
a viscous and an elastic response. A viscoelastic material will exhibit viscous flow under
constant stress, but a portion of mechanical energy is conserved and recovered after stress is
released. The viscoelastic nature of the VCC may be characterized in part by the ability of the
VCC to creep when agitated generally referred to as the Weissenberg effect. Specifically, the
Weissenberg effect is the tendency of some viscoelastic fluids to flow in a direction normal to
the direction of shear. The effect is manifested by behavior such as the climbing of a fluid up a
rotating rod.
[0036] In an embodiment, the VCC comprising a Sorel cement (e.g. THERMATEK™
rigid setting fluid) and a viscosifier has an increased plastic viscosity (PV) and yield point (YP)
when compared to a Sorel cement lacking a viscosifier. The plastic viscosity is an absolute
flow property indicating the flow resistance of certain types of fluids and is a measure of
shearing stress while the yield point refers to the resistance of the drilling fluid to initial flow,
or represents the stress required to start fluid movement In an embodiment, a VCC as
disclosed herein has a PV of greater than about 20, alternatively greater than about 80,
alternatively greater than about 100 and a YP of greater than about 1, alternatively greater than
about 20, alternatively greater than about 40. In an embodiment, the relationship between the
amount of viscosifier included in the VCC and the PV, YP or both is about linear.

[0037] The VCC disclosed herein may be used as a wellbore servicing fluid. As used
herein, a "servicing fluid" refers to a fluid used to drill, complete, work over, fracture, repair, or
in any way prepare a wellbore for the recovery of materials residing in a subterranean
formation penetrated by the wellbore. It is to be understood that "subterranean formation"
encompasses both areas below exposed earth and areas below earth covered by water such as
ocean or fresh water. Examples of servicing fluids include, but are not limited to cement
slurries, drilling fluids or muds, spacer fluids, fracturing fluids or completion fluids, all of
which are well known in the art. Without lirrutation, servicing the wellbore includes
positioning the VCC in the wellbore to isolate the subterranean formation from a portion of the
wellbore; to support a conduit in the wellbore; to plug a void or crack in the conduit; to plug a
void or crack in a cement sheath disposed in an annulus of the wellbore; to plug an opening
between the cement sheath and the conduit; to prevent the loss of aqueous or non-aqueous
drilling fluids into loss circulation zones such as a void, vugular zone, or fracture; to be used as
a fluid in front of cement slurry in cementing operations; to seal an annulus between the
wellbore and an expandable pipe or pipe string; or combinations thereof.
[0038] In an embodiment, the VCC may be introduced to the wellbore to prevent the loss
of aqueous or non-aqueous drilling fluids into loss-circulation zones such as voids, vugular
zones, and natural or induced fractures while drilling. The VCC may form a non-flowing,
intact mass inside the loss-circulation zone which plugs the zone and inhibits loss of
subsequently pumped drilling fluid, which allows for further drilling. For example, the VCC
may function as a plug that is placed into an annulus of the wellbore and prepares the formation
for placement of a second (e.g. cementitious) composition.
[0039] Alternatively, the VCC when placed in a wellbore may be allowed to set such that it
isolates the subterranean formation from a different portion of the wellbore, for example during

primary cementing. The VCC thus forms a barrier that prevents fluids in that subterranean
formation from migrating into other subterranean formations. In an embodiment, the wellbore
in which the composition is positioned belongs to a multilateral wellbore configuration. It is to
be understood that a multilateral wellbore configuration includes at least two principal
wellbores connected by one or more ancillary wellbores.
[0040] In an embodiment, the VCC may serve as a gravel packing fluid in gravel-packing
operations. Herein gravel packing refers to a method commonly utilized to prevent migration
of sand into wells and to maintain the integrity of subterranean formations. In gravel packing, a
permeable screen is placed against the face of a subterranean formation, followed by packing
gravel against the exterior of the screen. The size of the gravel particles used for this purpose
are larger than the sand particles but are also small enough to ensure that sand cannot pass
through voids between the particles. The gravel is typically carried to the subterranean
formation by suspending the gravel in a so-called gravel packing fluid and pumping the fluid to
the formation. The screen blocks the passage of the gravel but not the fluid into the
subterranean formation such that the screen prevents the gravel from heing circulated out of the
hole, which leaves it in place. The gravel is separated from the fluid as the fluid flows through
the screen leaving it deposited on the exterior of the screen.
[0041] In an embodiment, the VCC may be used for plug and abandonment of a well, i.e.
to prepare a well to be shut in and permanently isolated. A series of plugs comprising the VCC
may be set in the wellbore and tested at each stage for hydraulic isolation.
EXAMPLES
[0042] The invention having been generally described, the following examples are given as
particular embodiments of the invention and to demonstrate the practice and advantages

thereof. It is understood that the examples are given by way of illustration and are not intended
to limit the specification or the claims in any manner.
EXAMPLE 1
[0043] The effect of a quaternary material on the viscosity of a Sorel cement was
investigated. Specifically, the Sorel cement was THERMATEK™ rigid setting fluid which is a
mixture of MgO and MgCl2.6H2O commercially available from Halliburton Energy Services.
The THERMATEK™ rigid setting fluid slurry was prepared as follows: in a Waring blender;
450 grams of C-TEK was dissolved in 300 grams of water; 450 grams of THERMATEK™ LT
was added to the C-TEK solution to prepare the slurry. To the THERMATEK™ rigid setting
fluid slurry was added the indicated amounts of quaternary material using a stock solution of
AMMONXY SDBC which is a quaternary amidopropalkonium chloride commercially
available from Stepan. The concentration of the stock solution was 60%. At room temperature,
the rheological properties of the fluid were measured using FANN 35 viscometer at 3, 6,100,
200, 300, and 600 RPM. The viscosity at each mixing speed, plastic viscosity (centipoise) and
yield point (lbs/100 ft2) of the resultant slurries was measured in accordance with API
Recommended Practices 10B, Bingham Plastic Model and are given in Table 1.

[0044] A graph of the yield point and plastic viscosity as a function of the amount of
quaternary material is shown in Figure 1. The results demonstrate that the addition of

quaternary material to THERMATEK™ rigid setting fluid results in an increased plastic
viscosity and yield point. Furthermore, within the concentration range investigated the addition
of increasing amounts of quaternary material results in a linear increase in both the plastic
viscosity and yield point
EXAMPLE 2
[00451 The effect of the addition of quaternary material on the compatibility of
THERMATEK™ rigid setting fluid and oil-based muds was investigated. A THERMATEK™
rigid setting fluid slurry was prepared as follows: in a Waring blender; 450 grams of C-TEK
was dissolved in 300 grams of water; 450 grams of THERMATEK™ LT was added to the C-
TEK solution to prepare the slurry. To the THERMATEK™ rigid setting fluid slurry was
added 5 ml of a 83% solution of ARQUAD 83E which is a quaternary amine commercially
available from Stepan. To this mixture of THERMATEK™ rigid setting fluid and quaternary
material was added the indicated amount of PETROFREE LV which is a synthetic mud
commercially available from Halliburton Energy Services. At room temperature, the
Theological properties of the fluid was measured using a FANN 35 viscometer at 3, 6,100,200,
300, and 600 RPM and allowed to set at room temperature for 24 hours and the compressive
strengths of the set compositions determined The viscosity at each mixing speed, plastic
viscosity (centipoise) and yield point (lbs/100 ft2) of the resultant slurries was measured in
accordance with API Recommended Practices 10B, Bingham Plastic Model and are given in
Table 2.


[0046] The results demonstrate an increasing viscosity, plastic viscosity and yield point
with the addition of quaternary material to THERMATEK™ rigid setting fluid. Furthermore,
the THERMATEK™ rigid setting fluid and quaternary material formed a set mass with
appreciable compressive strength when the slurry was combined with 50% or less of oil-based
mud. Similar experiments conducted using PETROFREE LV organic carrier fluid, which is an
organic ester-based fluid, ACCOLADE which is an olefm/ester blend both of which are
commercially available from Halliburton Energy Services or diesel which is widely
commercially available as the mud also formed a set mass with appreciable compressive
strength when the slurry was combined with 50% or less of the mud.
[0047] While preferred embodiments of the invention have been shown and described,
modifications thereof can be made by one skilled in the art without departing from the spirit
and teachings of the invention. The embodiments described herein are exemplary only, and are
not intended to be lirniting. Many variations and modifications of the invention disclosed
herein are possible and are within the scope of the invention. Where numerical ranges or
limitations are expressly stated, such express ranges or limitations should be understood to
include iterative ranges or limitations of like magnitude falling within the expressly stated
ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10
includes 0.11, 0.12, 0.13, etc.). Use of the term "optionally" with respect to any element of a

claim is intended to mean that the subject element is required, or alternatively, is not required.
Both alternatives are intended to be within the scope of the claim. Use of broader terms such as
comprises, includes, having, etc. should be understood to provide support for narrower terms
such as consisting of, consisting essentially of, comprised substantially of, etc.
[0048] Accordingly, the scope of protection is not limited by the description set out above
but is only limited by the claims which follow, that scope including all equivalents of the
subject matter of the claims. Each and every claim is incorporated into the specification as an
embodiment of the present invention. Thus, the claims are a further description and are an
addition to the preferred embodiments of the present invention. The discussion of a reference
herein is not an admission that it is prior art to the present invention, especially any reference
that may have a publication date after the priority date of this application. The disclosures of
all patents, patent applications, and publications cited herein are hereby incorporated by
reference, to the extent that they provide exemplary, procedural or other details supplementary
to those set forth herein.

CLAIMS
1. A wellbore servicing composition comprising a metal oxide, a soluble salt and a
viscosifier wherein the viscosifier comprises a quaternary amide, a quaternary amide
ester, or combinations thereof.
2. The composition of claim 1 wherein the viscosifier comprises an amidopropalkonium
chloride with a chain length of greater than about C12.
3. The composition of claim 1 wherein the viscosifier is present in an amount of from .
about 0.05% to about 5% based on the total weight of the composition.
4. The composition of claim 1 wherein the metal oxide comprises an alkaline earth metal
oxide.
5. The composition of claim 4 wherein the alkaline earth metal oxide comprises
magnesium oxide.
6. The composition of claim 1 wherein the soluble salt comprises magnesium chloride,
sodium phosphate, potassium phosphate, ammonium phosphate or combinations
thereof.
7. The composition of claim 1 wherein the composition has a plastic viscosity of greater
than about 20.
8. The composition of claim 1 wherein the composition has a yield point of greater than
about 1.
9. The composition of claim 1 wherein a plot of the plastic viscosity as a function of the
amount of viscosifier is about linear.
10. The composition of claim 1 wherein a plot of the yield point as a function of the amount
of viscosifier is about linear.

11. The composition of claim 1 having a compressive strength of from about 50 psi to
about 20,000 psi.
12. The composition of claim 1 having a density of from about 4 ppg to about 25 ppg.
13. The composition of claim 1 further comprising an oleaginous fluid.
14. The composition of claim 13 wherein the oleaginous fluid is present in an amount of
from about 5% to 100 % by weight of the cement.
15. The composition of claim 1 further comprising a retarder.
16. The composition of claim 1 wherein the composition displays a right angle set.
17. The composition of claim 1 wherein the composition displays viscoelastic behavior.
18. A wellbore servicing composition comprising magnesium oxide, a chloride or
phosphate salt and a quaternary material.
19. The composition of claim 18 wherein the quaternary material comprises a quaternary
amide, a quaternary amide ester or combinations thereof.
20. The composition of claim 18 wherein the quaternary material is present in an amount of
from about 0.05 wt. % to about 5 wt. %.
21. A wellbore servicing composition comprising magnesium oxide, magnesium chloride,
and a quaternary material wherein the quaternary material comprises a quaternary
amide, a quaternary amide ester or combinations thereof and wherein the quaternary
material is present in an amount of from about 0.05 wt.% to about 5 wt.% and a plot of
the composition's plastic viscosity as a function of the amount of quaternary material is
about linear.
22. The composition of claim 21 further comprising an oleaginous fluid.
23. A method of servicing a wellbore in contact with a subterranean formation comprising:
viscosifying a cement composition comprising a metal oxide and a soluble salt;

placing the viscosified cement composition in the wellbore; and
allowing the composition to set
24. The method of claim 23 wherein viscosifying the cement composition comprises
contacting the cement composition with a quaternary material.
25. The method of claim 24 wherein the quaternary material comprises a quaternary amide,
a quaternary amide ester or combinations thereof.
26. The method of claim 24 wherein the quaternary material comprises an
amidopropalkonium chloride with a chain length of greater than about C12.
27. The method of claim 24 wherein the quaternary material is present in an amount of
from 0.05% to about 5% based on the total weight of the composition.
28. The method of claim 23 wherein the viscosified cement composition has a plastic
viscosity of greater than about 20.
29. The method of claim 23 wherein the viscosified cement composition has a yield point
of greater than about 1.
30. The method of claim 23 wherein a plot of the viscosified cement composition yield
point as a function of the amount of quaternary material is about linear.
31. The method of claim 23 wherein a plot of the viscosified cement composition plastic
viscosity as a function of the amount of quaternary material is about linear.
32. The method of claim 23 wherein the viscosified cement composition displays a right
angle set.
33. The method of claim 23 wherein the set viscosified cement composition has a
compressive strength of from about 50 psi to about 20,000 psi.
34. The method of claim 23 wherein the viscosified cement composition has a density of
from about 4 ppg to about 25 ppg.

35. The method of claim 23 further comprising contacting the cement composition with an
oleaginous fluid.
36. The method of claim 35 wherein the oleaginous fluid is present in an amount of from
about 5 % to about 100% by weight of cement.
37. The method of claim 23 wherein the metal oxide comprises an alkaline earth metal
oxide.
38. The method of claim 37 wherein the alkaline earth metal oxide comprises magnesium
oxide.
39. The method of claim 23 wherein the soluble salt comprises magnesium chloride,
sodium phosphate, potassium phosphate, ammonium phosphate or combinations
thereof.
40. The method of claim 23 wherein the cement composition further comprises a retarder.
41. The method of claim 23 wherein the method of servicing a wellbore comprises treating
lost circulation, isolating a gravel pack, supporting a conduit, plugging a void or crack
in the conduit, plugging an opening between a cement sheath and a conduit, spacing
fluid in front of a cement slurry, sealing an annulus or combinations thereof.
42. The method of claim 23 wherein the viscosified cement composition displays
viscoelastic behavior.
43. A method of cementing a wellbore comprising:
preparing a cement composition comprising magnesium oxide, a chloride or phosphate
salt, and a quaternary material;
placing the cementitious composition into the wellbore; and
allowing the cementitious composition to set.

44. A method of viscosifying a Sorel cement comprising contacting the cement
composition with quaternary material.

A wellbore servicing composition is described comprising a metal oxide, a soluble salt and a viscosifier wherein the viscosifier comprises a quaternary amide, a quaternary amide ester, or combinations thereof. A method of servicing a wellbore in contact with a subterranean formation is also described, the method comprising viscosifying a cement composition comprising a metal oxide and a soluble salt, placing the viscosified cement composition in the wellbore, and allowing the composition to set.