Note: Descriptions are shown in the official language in which they were submitted.
CA 02745017 2011-06-28
Drilling Fluid and Methods
Field
The invention relates to fluids used for drilling and completing oil wells and
in particular
those useful for deterring tar/heavy oil accretion on metal surfaces.
Background
The process of drilling a hole in the ground for the extraction of a natural
resource
requires a fluid for removing cuttings from the wellbore, controlling
formation pressures
and maintaining hole stability. Drilling through oil sand formations causes
problematic
accretion of tar on drilling apparatus. Bitumen accretion on metal surfaces
impairs
drilling operations by blinding shale shaker screens, plugging centrifuges and
drill bits,
torque and drag increase and stuck pipe or casing. Standard drilling practices
through
oil sand formations, which are generally unconsolidated, can also lead to hole
instability
problems.
If these formations are drilled horizontally, torque and drag between the
formation and
the drill string can limit both the rate of drilling and the ultimate length
of the horizontal
section that can be achieved.
Solvents, surfactants and viscosifiers have been used in drilling fluids for
drilling through
heavy oil, including bitumen-containing formations, In addition, or
alternately, drilling
fluids have been chilled to deter accretion and enhance hole stability.
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Summary
A drilling fluid and a method for drilling have been invented.
In accordance with one aspect of the present invention, there is provided an
aqueous
drilling fluid comprising: 0.01 to 0.5% by weight of a branched alcohol
ethoxylate and/or
a capped alcohol ethoxylate; and 0.01 % to 0.5% by weight of a detergent
builder.
In accordance with another aspect of the present invention, there is provided
a method
for drilling a wellbore through a formation, the method comprising: operating
a drilling
assembly to drill a wellbore and circulating a drilling fluid through the
wellbore as it is
drilled, the drilling fluid being water-based and including: 0.01 to 0.5% by
weight of a
branched alcohol ethoxylate and/or a capped alcohol ethoxylate; and a
detergent
builder.
It is to be understood that other aspects of the present invention will become
readily
apparent to those skilled in the art from the following detailed description,
wherein
various embodiments of the invention are shown and described by way of
illustration.
As will be realized, the invention is useful for other and different
embodiments and its
several details are capable of modification in various other respects, all
without
departing from the spirit and scope of the present invention. Accordingly the
drawings
and detailed description are to be regarded as illustrative in nature and not
as
restrictive.
Detailed description of various embodiments
A drilling fluid and a method for drilling a wellbore has been invented for
use in
formations bearing heavy oil, also called bitumen or tar. The drilling fluid
and method
are useful to limit and possibly remove tar accretion on metal surfaces,
reduce torque
and drag and/or to maintain borehole stability, while working with standard
viscosifiers
and other chemicals used in drilling fluids. The drilling fluid and method may
therefore
be environmentally responsible and economically viable.
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A drilling fluid according to the present invention includes a non-ionic
surfactant
including at least one of (i) a branched alcohol ethoxylate or (ii) a capped
alcohol
ethoxylate; and a detergent builder.
In this drilling fluid, it is believed that the non-ionic surfactant acts to
limit tar sand
accretion to metal surfaces perhaps by adsorbing onto surfaces or interfaces
to change
the interfacial tensions and/or the electrical potentials. The non-ionic
surfactant may be
effective in producing stearic barriers for prevention of tar deposition. The
adsorption of
the surfactant onto the bitumen will have the hydrophilic group oriented
toward the
metal. Surfactant molecules adsorbed onto the bitumen particles will have the
hydrophilic group oriented toward the metal surfaces. Since viscosifiers may
be
anionic, a non-ionic surfactant avoids a reaction such as precipitation when
operating
with the viscosifiers. It is desired that the non-ionic surfactants have a
water wetting,
detergent characteristics, for example, that may have a hydrophilic-lipophilic
balance
(HLB) number of 11 to 15. Surfactants with an HLB over 15 may dissolve the
bitumen
and such solubility is generally not desirable as this may lead to hole
instability, high
washouts and waste volumes. The non-ionic surfactant may also be low foaming.
Modifying the structure of the surfactant's molecule to keep the surface
activity while
producing unstable foam can be realized by replacing the straight-chain
lipophilic group
with a branched chain or by using two different sized or shaped lipophilic
groups.
Changes may be made on the hydrophilic part of the molecule by placing the
second
lipophobic group into the molecule at some distance, for example a few carbon
atoms,
or by putting two bulky lipophobic groups on the same carbon atom. Some useful
non-
ionic surfactants include capped or branched alcohol ethoxylate, such as for
example
ethoxylated alcohols, ethoxylated propoxylated alcohols, etc. "Capped" implies
that -
OH moieties are capped with a moiety such as a short alkyl group. Some
commercially
available non-ionic surfactants that may be useful in a drilling fluid may
include one or
more of:
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= alkyl polyethylene glycol ethers based on C 10-guerbet alcohol and ethylene
oxide, for example, available as Lutensol XP 60TM, Lutensol XP 69TH, Lutensol
XP 70TM, Lutensol XP 79TM, Lutensol XP 80TM, Lutensol XP 89TH, Lutensol XP
90TM, Lutensol XP 99TM produced by BASF. The Lutensol(r) XP products are
manufactured by reacting the C10-alcohol with ethylene oxide in stoichiometric
proportions. The numeric portion of the product name indicates the general
degree of ethoxylation;
= chlorine capped ethoxylated C10-14-ISO alcohols such as are available under
the trademark Antarox BL-330TM produced by Rhodia;
= chlorine capped ethoxylated C9-11-ISO, C10 rich alcohols such as are
available
under the trademark Antarox LF-330 produced by Rhodia;
= end-capped guerbet alcohol ethoxylate for example, available as Dehypon G
2084TIl produced by Cognis;
= branched secondary alcohol ethoxylates for example, available as Tergitol
TMNTM Series available from Dow.
The use of a non-ionic surfactant according to those described gives a
drilling fluid
detergent characteristics.
A drilling fluid according to the present invention further includes a
detergent builder. As
will be appreciated, a detergent builder enhances the action of a detergent.
Generally,
it is believed that builders operate as water wetting agents and remove
cations such as
of calcium (Ca++) and magnesium (Mg++), whose presence in the system may
impair the
detergent action. As such, a builder may reduce the amount of surfactant to be
used
over a system where no builder is used. This may offer numerous benefits
including
reducing the amount of tar which is dissolved into the drilling fluid, and
thereby
enhancing the reuse of the drilling fluid.
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Inorganic builders of interest include phosphates, silicates, and oxygen
releasing
compounds such as perborates and borates. Some builders that may be of
interest
include one or more of:
= phosphates including trisodium phosphate (TSP) and pyrophosphates, for
5 example, tetra-potassium pyrophosphate (TKPP), sodium acid pyrophosphate
(STPP), etc. The phosphate type of builders may also have beneficial
dispersing
properties, considering that significant amounts of reactive clays may be
drilled
and no additional dispersant may be required;
= borates including for example sodium metaborate, sodium tetraborate
pentahydrate. While some builders may have some adverse environmental
effect, borates are believed to be environmentally friendly and therefore may
be
environmentally of interest in a drilling fluid formulation;
= zeolites including sodium aluminum silicates readily replace their sodium
ions
with Ca2+ or Mg2+ ions. Complex systems of zeolite/polyacrylate may also be
used;
= nitrilotriacetic acid (NTA);
= ethylenediaminetetracetic acid (EDTA) and its salts;
= citrates; or
= potassium or sodium silicates and metasilicates. This type of builder may
increase the friction coefficient in the system.
The use of a builder in the drilling fluid enhances performance of the
surfactant such
that generally less surfactant needs to be used compared to a system without a
builder
and the drilling fluid may be reused.
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Where foam control is of interest, pyrophosphates have been found to be
particularly
useful. If the drilling fluid exhibits adverse foaming properties,
pyrophosphate builder
such as tetra-potassium pyrophosphate (TKPP) or sodium acid pyrophosphate
(STPP)
may be added. If drilling with pyrophosphate builder and foaming begins to
become an
issue, the concentration of the pyrophosphate may have to be topped up. This
may
occur, for example, when drilling in clays, which tends to deplete
pyrophosphates.
In one embodiment, a water-based drilling fluid may be prepared using 0.01-
1.5% by
weight of a non-ionic surfactant; and 0.01 %-1.0% by weight of a detergent
builder. In
laboratory testing, it was determined that a concentration of at least 0.5% by
weight of a
non-ionic surfactant was necessary. However, in field tests it was determined
that
useful activity could be achieved with concentrations as low as 0,01% of the
non-ionic
surfactant up to 0.5% by weight as well as concentrations of 0.5%-1.5% by
weight. As
well in laboratory testing, it was determined that a concentration of at least
0.5% by
weight of the detergent builder was necessary. However, in field tests it was
determined that useful activity could be achieved with concentrations of
builder as low
as 0.01% and through to but less than 0.5% by weight as well as concentrations
of
0.5%-1.0% by weight.
In one example embodiment, a water-based drilling fluid may be prepared
including:
0.01 to <0.5% by weight of an alkyl polyethylene glycol ester and/or a
chlorine capped
ethoxylated C9-11 (C10 rich) alcohol; and 0.01% to <0.5% by weight of a
phosphate-
type builder, and/or a silicate-type builder.
A drilling fluid according to the present invention may also include, if
desired, a
lubricant, also termed a secondary surfactant. In field testing, it was
determined that
lubricant may play a more significant role in anti-accretion and drill rate
performance
than originally thought. In some drilling operations, the anti-accreting
results were
observed without lubricant, but often the addition of lubricant was found to
improve the
anti-accretion results with the surfactant and builder. The lubricant may act
to soften
the tar and provide a lubricating action to assist drilling and running liners
into long
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horizontal sections of a wellbore. The lubricant may be non-ionic. High flash
point
vegetable oils, such as those having a flash point greater than 148 C, may be
of some
use in the present drilling fluids. Useful lubricants may include, for
example, plant
product oils and derivatives thereof including fatty acid methyl esters for
example with
an HLB of about 6, such as are commonly available as vegetable oil or
derivatives
thereof, soybean oil or derivatives such as soya methyl ester for example,
commercially
available as SoyClearTM products by AG Environmental Products, LLC or canola
methyl
ester for example, commercially available as OleocalTM canola methyl ester
products by
Lambent Technologies Corp., or canola oil or its derivatives. Lubricants may
be added
to the drilling fluid when the fluid is prepared, directly into the tanks and
may alternately
or in addition by added by application first to metal surfaces such as shale
shakers, etc.
at surface to thereby enter the drilling fluid stream.
In one embodiment, a water-based drilling fluid may be prepared using
surfactant,
builder and 0.01-1.5% by weight secondary surfactant (also termed a lubricant)
such as,
for example, a methyl ester of soybean oil. In laboratory testing, it was
determined that
a concentration of at least 0.5% by weight of a secondary surfactant was
useful.
However, in field tests it was determined that useful activity could be
achieved with
concentrations as low as 0.01 % by weight of the secondary surfactant through
to the
0.5% by weight concentrations identified in lab tests. As such, in the field
the drilling
fluid may be useful with concentrations of 0.01 to <0.5% of a lubricant such
as a plant-
based oil.
A drilling fluid according to the present invention may also include, if
desired, a
viscosifier. A drilling fluid need not include a viscosifier if there is
sufficient hole
cleaning. In small diameter holes, for example, a viscosifier may not be
needed.
However, viscosifiers provide carrying capacity to a drilling fluid and, so,
in some cases
may be of interest. Viscosifiers, for example, increase the viscosity of
drilling fluid so
that it can carry cuttings along with the flow of drilling fluid. Viscosifiers
may also act to
reduce fluid loss by inhibiting fluid infiltration to the formation.
Viscosifiers may prevent
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deposition or re-deposition of the bitumen on metal surfaces by suspending the
tar and
tar sand particles in the fluid. Some common viscosifiers useful in
embodiments of the
present drilling fluid may include, for example, any of: xanthan gum, wellan
gum,
schleroglucan and/or guar gum.
In one embodiment, a water-based drilling fluid may be prepared using
surfactant,
builder and 0.1-0.4% by weight viscosifier. In laboratory testing, it was
determined that
a concentration of at least 0.2% by weight of a viscosifier was useful.
However, in field
tests it was determined that useful activity could be achieved with
concentrations as low
as 0.1% by weight of the viscosifier through to the 0.2% by weight
concentrations
identified in lab tests.
Fluid loss reducers may also be used in a drilling fluid according to the
present invention
if desired. Some common fluid loss reducers include, for example, starches,
PAC
(polyanionic cellulose) and/or CMC (carboxy methyl cellulose). Some of these
chemicals may also have a viscosifying function. The fluid loss reducers may
provide
steric stabilization for the non-ionic surfactants.
The drilling fluid may contain various defoamers such as silicone defoamers,
fatty
alcohol ethoxylate defoamers, stearate defoamers, etc., as desired, alone or
in
combination. In one embodiment, silicone defoamer is used alone or with
aluminum
stearate defoamer. In another embodiment, fatty alcohol ethoxylate defoamer is
used
alone or with aluminum stearate defoamer in an amount effect to control
foaming.
Some components of the drilling fluid may operate best if pH is controlled.
For
example, the fluid may be more basic with, for example, the pH of the fluid
maintained
at 10 or more. In one embodiment, the fluid is maintained at a pH of 10.5 or
more.
Caustic or other basic additives may be employed for pH control.
The drilling fluid is useful to inhibit tar accretion on metal surfaces.
However, it may
also be used where torque and drag issues are of concern, even apart from
concerns
regarding accretion. In one aspect the drilling fluid can be used in a method
for drilling
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a wellbore into a heavy oil formation such as an oil sand containing
formation. In such a
method, without the present additive, tar and drill cuttings such as sand can
adhere as
accretions to the metal surfaces of the drilling assembly, and metal surfaces
in the
wellbore such as liners and casing. Thus, the present method includes
circulating the
aqueous-based drilling fluid, as described above, while operating a drilling
assembly to
drill the wellbore.
In another aspect the drilling fluid may be used to remove existing accretions
on metal
surfaces as by circulation through a wellbore or washing of the wellbore
surface
systems.
The drilling fluid may be reused repeatedly by simply removing the solids it
contains.
It will be appreciated that a drilling assembly can include, for example, a
drill bit and
possibly other cutting surfaces, a drill string, and various control and
monitoring subs.
It will also be appreciated, that it may not be necessary to use the same
drilling mud
throughout an entire drilling operation. For example, a drilling mud selected
to control
accretion may not be required during drilling through the over burden. The
method is
particularly useful during drilling wherein oil sand drill cuttings are being
produced and
very useful where there is more frequent contact between metal surfaces or
metal
surfaces and the wellbore wall such as, for example, during drilling of the
build section
and the horizontal section of a wellbore.
Where, during drilling using a drilling fluid according to the present
invention, accretions
are being deposited to an undesirable extent, the composition can be adjusted
to, for
example, increase surfactant or secondary surfactant, to inhibit further
undesirable
amounts of accretion and possibly to remove, at least to some degree, those
accretions
already deposited.
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Laboratory Examples
In the following laboratory examples, the test additives are referenced by the
product
names set out in Table 1.
Table 1.
Product Name Chemical Name % by
weight
Poly(oxy-1,2-ethanediyl), alpha
(phenylmethyl) - omega - (1,1,3,3- 85
tetramethylbutyl) phenoxy-
Product A Glycols, polyethylene,
mono[(1,1,3,3-tetramethylbutyl) 15
phenyl] ether
Polyethylene glycol <3
Oxirane, methyl-, polymer with
oxyrane, mono(octylphenyl) ether, >99
Product B branched
Polyethylene glycol <1
Product C Modified polyethoxylated alcohol 100
C8-C10 ethoxylated propoxilated >98
Product D Polyethylene glycol <2
Butanedioic acid, octenyl- <63
Product E Anionic surfactant >35
Ethoxylated 2,4,7,9-tetramethyl 5 100
Product F decyn-4,7-diol
Product G Poly(oxy-1,2-ethanediyl), alpha.(2- 100
ro the t I)-omega- h drox -
Poly(oxy-1,2-ethanediyl), alpha.(2- 100
Product H propylheptyl)-omega- hydroxy-
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Poly(oxy-1,2-ethanediyl),
Product I alpha-(2-propylheptyl)-omega- 100
hydroxy-
Poly(oxy-1,2-ethanediyl),
Product J alpha-(2-propylheptyl)-omega- 100
hydroxy-
Product K Ethoxylated C9-10 alcohols >99.5
Product L Ethoxylated C8-10 alcohols >99.5
Chlorine capped ethoxylated C10- >94
Product M 14 alcohols
Chlorine capped ethoxylated C9-11 >94
Product N alcohols, C10 rich
Triterpene, Sapogenin glycosides, 100
Product 0 vegetal steroid
Product P Sodium tetraborate decahydrate 100
Product Q Tetrapotassium pyrophosphate 100
Product R Sodium Metaborate 100
Product S Sodium silicate 82.5
Product T Zeolite 78-82
Product U Pine oil 100
Product V Methyl ester of soybean oil 100
Product W Turpentine oil 100
Product X Diethyl Phthalate 100
Product Y Derived from canola oil 100
Product Z Sodium tetraborate pentahydrate 100
Milligan MBTI Methyl ester of canola oil 100
P01D
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Milligan MBTI Methyl ester of canola oil 100
P03D
Milligan MBTI Methyl ester of canola oil 100
P04D
Milligan MBTI Methyl ester of canola oil 100
P05D
Milligan MBTI Methyl ester of canola oil 100
P06D
Tables 2 to 14 includes results from various tests conducted, wherein the
samples are
prepared by adding 200 mL of water in a mixing cup followed by the test
additives and
40 g of tar sand core material. Each sample is then mixed 15 to 20 seconds on
a
multimixer prior to placement in 260 mL rolling cell with a corresponding pre-
weighed
metal bar. The samples are rolled for 30 min. Then the tar accretion is
measured by
weight gain of the bars and by observation. The tests are run at room
temperature.
Table 2.
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number L/m3 bar Cell on Lid
Weight
(g)
1 Blank 1.3 100% 100%
2 Product A 5 ** 3.0 50% 5%
3 Product B 5 ** 2.0 40% 60%
4 Product C 5 **** 3.4 90% 95% Milky in
water
Thin
5 Product D 5 * 1.9 90% 100%
6 Product E 5 * 3.5 95% 100% Milky in
water
Thick
Table 3
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number Um3 bar Cell on Lid
Weight
(g)
1 Blank 2.6 100% 80%
2 Product B 10 ** 3.1 trace Trace
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3 Product B 5 ** 1.6 50% 35%
Product Y 10
4 Product B 10 **** 3.8 10% 30%
Product Y 10
Product B 5 **` 2.8 80% 30%
Product Y 20
6 Product Y 10 1.8 100% 100% Oil and tar
separates
from water
Table 4
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number L/m3 bar Cell on Lid
Weight
(g)
1 Product A 10 4.5 60% 2%
2 Product A 20 **** 5.6 1 % 0% The tar is
sticking to
the bar
3 Product A 5 ** 0.6 90% 100%
Product V 10
4 Product A 5 * 1.4 90% 10%
Product V 20
5 Product A 10 ** 2.0 95% 5%
Product V 20
6 Product V 30 0.3 Oil with Oil
dissolv with
ed tar dissol
ved
tar
Table 5
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number L/m3 bar Cell on Lid
Weight
(g)
1 Product A 5 ** 1.5 95% 3%
Product W 10
2 Product A 10 *** 1.1 20% 25%
Product W 10
3 Product A 10 *** 0.5 20% 100%
Limonene 20
4 Product A 5 ** 1.1 20% 40%
Limonene 10
5 Product A 10 *** 2.7 20% 25%
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Limonene 10
6 Product A 10 *** 2.6 15% 100%
Limonene 20
Table 6
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number L/m3 bar Cell on Lid
Weight
1 Product F 5 * 2.8 90% 40%
2 Product G 5 ** 1.9 90% 5%
3 Product H 5 **** 1.1 90% 95% Bottom of
cell clean
4 Product I 5 **** 1.8 100% 60%
Product J 30 ***** 2.5 80% 40%
6 Limonene 30 0.2 0% 5% Film
Table 7
5
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number Um3 bar Cell on Lid
Weight
(g)
1 Product A 10 - 0.1 No No Some oily
Limonene 20 film
Product Q 5
2 Product B 10 *** 0.1 No No Some oily
Limonene 20 film
Product Q 5
3 Product D 10 ** 0.1 No No Some oily
Limonene 20 film
Product Q 5
4 Product E 10 ** 0.1 No No Some oily
Limonene 20 film
Product Q 5
5 Product G 10 **** 0.1 No No Totally
Limonene 20 clean
Product Q 5
6 Product H 10 **** 0.1 No No Totally
Limonene 20 clean
Product Q 5
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Table 8
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number Um3 bar Cell on Lid
Weight
(g)
1 Product G 10 - - -
Limonene 15
Product Q 5
Defoamer 5
Silicone
2 Product H 10 * - - -
Limonene 15
Product Q 5
Defoamer 5
Silicone
3 Product G 10 * - - -
Product X 15
Product Q 5
Defoamer 5
Silicone
4 Product H 10 * - - -
Product X 15
Product Q 5
Defoamer 5
Silicone
5 Product G 10 * - - - Cleanest
Product V 15
Product Q 5
Defoamer 5
Silicone
6
Table 9
5
Sample Product Con Foaming Tar on Tar on Tar Notes
Number c. bar Cell on Lid
Urn Weight
3 (g)
1 Xanthan 5 * - - -
Gum
Product H 5
Product V 10
Product Q 5
Defoamer 10
Silicone
2 Xanthan 5 * - - -
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Gum
Product K 5
Product V 10
Product Q 5
Defoamer 5
Silicone
3 Xanthan 5 * - - -
Gum
Product L 10
Product V 5
Product Q 5
Defoamer 5
Silicone
4 Xanthan 5 * - 5%
Gum 5
Product M 10
Product V 5
Product Q -
Defoamer
Silicone
Xanthan 5 * - - -
Gum 5
Product N 10
Product V 5
Product Q -
Defoamer
Silicone
6 Xanthan 5 * 1.4 trace - Has an oily
Gum film
Product 0 5
Product V 10
Product Q 5
Defoamer -
Silicone
Table 10
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number Um3 bar Cell on Lid
Weight
(9)
1 Blank 12.8 30% 90%
2 Product N 10 ** - - -
Product V 10
Product Q 5
Defoamer -
Silicone
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3 Product N 10 ** 0.7 - -
Product V 10
Product P 5
Defoamer -
Silicone
4 Product N 10 ** 0.5 5% -
Product V 10
Product X 10
Product P 5
Defoamer -
Silicone
Product P 5 7.4 50% 100%
6 Product Q 5 3.2 15% 80%
Table 11
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number L/m3 bar Cell on Lid
Weight
(g)
1 Xanthan 4 - - - -
Gum
Product H 5
Product V 10
Product Q 5
2 Xanthan 4 - - trace - Easy to
Gum clean with
Product H 5 water
Product V 10
Product S 5
3 Xanthan 4 - - 5% - Easy to
Gum clean with
Product H 5 water
Product V 10
Product T 5
100
4 Xanthan 4 - - - -
Gum
Product N 5
Product V 10
Product Q 5
5 Xanthan 4 - - trace - Easy to
Gum clean with
Product N 5 water
Product V 10
Product S 5
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6 Xanthan 4 - - 5% - Easy to
Gum clean with
Product N 5 water
Product V 10
Product T 5
100
Table 12
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number L/m3 bar Cell on Lid
Weight
(g)
1 Xanthan 4.2 - - - - -
Gum
Product H 5
Milligan 10
MBTI 5
P01 D
Product Q
2 Xanthan 4.2 - - - - -
Gum
Product H 5
Milligan 10
MBTI 5
P03D
Product Q
3 Xanthan 4.2 - - - - -
Gum
Product H 5
Milligan 10
MBTI 5
P04D
Product Q
4 Xanthan 4.2 - - - - -
Gum
Product H 5
Milligan 10
MBTI 5
P05D
Product Q
Xanthan 4.2 - - - - -
Gum
Product H 5
Milligan 10
MBTI 5
P06D
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Product Q
6 Xanthan 4.2 - - - - -
Gum
Product H 5
Product U 10
Product Q 5
Table 13
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number Um3 bar Cell on Lid
Weight
9)
1 Blank - 11.4 30% - -
2 Xanthan 4.0 - - - - -
Gum
Product H 5
Product V 10
Product Q 5
Defoamer 2
Silicone
3 Xanthan 4.0 - - - - -
Gum 5
Product H 10
Product V 5
Product R 2
Defoamer
Silicone
4 Xanthan 4.0 - - - - -
Gum
Product H 5
Product V 10
Product Z 5
Defoamer 2
Silicone
Xanthan 4.0 - - - - -
Gum
Product H 5
Milligan 10
M BTI 5
P06D 2
Product Q
Defoamer
Silicone
6 Xanthan 4.0 - - - - -
Gum
Product H 5
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Product U 10
Product Q 5
Defoamer 2
Silicone
Table 14.
Sample Product Conc. Foaming Tar on Tar on Tar Notes
Number L/m3 bar Cell on Lid
Weight
(g)
1 Blank - 7.6 100% Trace
2 Xanthan 4.0 - 2.1 Trace Trace
Gum
Product V 10
3 Xanthan 4.0 - 1.6 Trace Trace
Gum
Product V 10
Product H 5
4 Xanthan 4.0 - 1.8 Trace Trace
Gum
Product V 30
5 Xanthan 4.0 - 0.5 Trace Clean
Gum
Product H 10
Product Q 5
6 Xanthan 4.0 - 2.4 Trace Clean
Gum
Product H 10
Product V 10
5
Example 15. Lubricity tests were conducted using a baroid lubricity meter,
which
provides a reading of the friction co-efficient (CoF). A solution of xanthan
gun (4 kg/m3)
in water was tested and generated a CoF reading of 0.30. Another aqueous
solution
was prepared including xanthan gun (4 kg/m3), alkyl polyethylene glycol ether
(Lutensol
10 XP 79) (10 L/m3), and soya methyl ester (50L/m3) and this generated a CoF
reading of
0.20. The CoF was reduced from 0.3 to 0.2 with the addition of the two
products.
Field Tests:
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Example A:
Background: In Alberta, Canada; Drilled 156mm hole into the Ft. McMurray
formation.
The Ft. McMurray formation is an unconsolidated sandstone containing 30% v/v
bitumen. Drilling rate was approximately 200m/hr.
Drilling Fluid: A fresh water based drilling fluid including: xanthan gum for
viscosity, a
polyanionic cellulose polymer (Drispac Regular) for fluid loss control, a
silicone based
defoamer, caustic to control the pH at 10.5, a deflocculant additive (Desco
CF), an
amine based shale inhibitor and a builder (625 kg of TKPP) was used to drill
into the Ft.
McMurray formation. The shaker screens were monitored for accretion. When sand
started to stick to the shakers, one pail (20L) of surfactant (Lutensol XP 79)
and one pail
(20L) of a soya bean-based lubricant were added to the drilling fluid,
equating to
concentrations of approximately 0.04% of each of the surfactant and the
lubricant in the
drilling fluid. After addition of the surfactant and lubricant, accretion no
longer occurred
on the shaker screens.
As drilling proceeded into a lateral, horizontal section in the formation,
concentrations of
1 to 3 L/m3 of the surfactant were required to continue to prevent accretion.
Example B:
Background: In Alberta, Canada; Drilled 311 mm hole to Intermediate Casing
Depth of
665mMD and casing set at -90 degrees inclination in the Ft. McMurray
formation. Set
and cement 244.5 mm casing.
Drilling Fluid: A fresh water based drilling fluid including: xanthan gum for
viscosity, a
polyanionic cellulose polymer (Drispac Regular) for fluid loss control, a
silicone based
defoamer, caustic to control the pH at 10.5, a deflocculant additive (Desco
CF), an
amine based shale inhibitor and a builder (625 kg of TKPP) was used to drill
into the Ft.
McMurray formation. Just above the Ft. McMurray bitumen 100L of anti-accretion
surfactant (Lutensol XP 79) and 100 L of soya bean/canola oil-based lubricant
were
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added to approximately 58.4 m3 of circulating volume of drilling fluid. This
equates to
concentrations of approximately 1.7 L/m3 of both the surfactant and the
lubricant in the
drilling fluid. This section was successfully drilled, cased and cemented
terminating in
the Ft. McMurray formation.
Example C:
Background: In Alberta, Canada; Drilled 311 mm hole to Intermediate Casing
Depth of
682mMD and casing set at -90 degrees inclination in the Ft. McMurray
formation. Set
and cement 244.5 mm casing,
Drilling Fluid: A fresh water based drilling fluid including xanthan gum for
viscosity, a
polyanionic cellulose polymer (Drispac Regular) for fluid loss control, a
silicone based
defoamer, caustic to control the pH at 10.5, an amine based shale inhibitor
and a
builder (675 kg of TKPP) was used to drill into the Ft. McMurray formation.
Just above
the Ft. McMurray bitumen 20L of anti-accretion surfactant (Lutensol XP 79) and
20 L of
plant oil-based lubricant (vegetable oil) were added to approximately 92.9 m3
of
circulating volume of drilling fluid. This equates to concentrations of
approximately 0.22
L/m3 of both the surfactant and the lubricant in the drilling fluid. This
section was
successfully drilled, cased and cemented terminating in the Ft. McMurray
formation.
The previous description of the disclosed embodiments is provided to enable
any
person skilled in the art to make or use the present invention. Various
modifications to
those embodiments will be readily apparent to those skilled in the art, and
the generic
principles defined herein may be applied to other embodiments without
departing from
the spirit or scope of the invention. Thus, the present invention is not
intended to be
limited to the embodiments shown herein, but is to be accorded the full scope
as
defined in the claims, wherein reference to an element in the singular, such
as by use of
the article "a" or "an" is not intended to mean "one and only one" unless
specifically so
stated, but rather "one or more". All structural and functional equivalents to
the
elements of the various embodiments described throughout the disclosure that
are
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known or later come to be known to those of ordinary skill in the art are
intended to be
encompassed by the elements of the claims. Moreover, nothing disclosed herein
is
intended to be dedicated to the public regardless of whether such disclosure
is explicitly
recited in the claims. No claim element is to be construed under the
provisions of 35
USC 112, sixth paragraph, unless the element is expressly recited using the
phrase
"means for" or "step for".
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