Note: Descriptions are shown in the official language in which they were submitted.
CA 02351088 2001-05-11
WO OOIZ7945 PCT/US99I26639
INVERT EMULSION lIRIE:L.ING FLUIDS HAVING NEGATIVE ALKALINITY
BACKGROUND OF THE INVENTION
2 Invert emulsion fluids, i.e. emulsions in which the non-oleaginous fluid is
the
3 discontinuous phase and the oleaginous fluid is the continuous phase, are
employed in drilling
processes for the development of oil or gas sources, as well as, in geothermal
drilling, water
drilling, geoscientific drilling and mine drilling. Specif tally, the invert
emulsion fluids are
6 conventionally utilized for such purposes as providing stability to the
drilled hole, forming a
thin filter cake, lubricating the drilling bore and the downhole area and
assembly, and
8 penetrating salt beds without sloughing or enlargement of the drilled hole.
9 OiI-based drilling fluids are generally used in the form of invert emulsion
muds. An
invert emulsion mud consists of three-phases: an oleaginous phase, a non-
oleaginous phase and
11 a finely divided particle phase. Also typically included are emulsifiers
and emulsif er systems,
lz weighting agents, fluid loss additives, viscosity regulators and the like,
for stabilizing the
13 system as a whole and for establishing the desired performance properties.
Full particulars can
t4 be found, for example, in the Article by P. A. Boyd et al entitled "New
Base Oil Used in Low
Toxicity Oil Muds" in the 3ournal of Petroleum Technology, 1985, I37 to I42
and in the Article
16 by R. B. Bennet entitled "New Drilling Fluid Technology-Mineral Oil Mud" in
Journal of
1~ Petroleum Technology, 1984, 975 to 981 and the literature cited therein.
1s The components of the invert emulsion fluids include an oleaginous liquid
such as
19 hydrocarbon oil which serves as a continuous phase, a non-oleaginous liquid
such as water or
2o brine solution which serves as a discontinuous phase, and an emulsifying
agent. As used herein,
2t emulsifying agent and surfactant are used interchangeably. The emulsifying
agent serves to
22 lower the interfacial tension of the liquids so that the non-oleaginous
liquid may form a stable
23 dispersion of fine droplets in the oleaginous Liquid. A full description of
such invert emulsions
24 may be found in Composition and Properties of Drilling and Completion
Fluids, 5th Edition, H.
C. H. barley. George R. Gray, Gulf Publishing Company, 1988, pp. 328-332, the
contents of
26 which are hereby incorporated by reference.
27 Lime or other alkaline materials are typically added to conventional invert
emulsion
28 drilling fluids and muds to maintain a reserve alkalinity. See, for
example, API Bulletin RP
z9 13B-2, 1994, p. 22 which describes a standard test for determining excess
Lime in drilling mud.
See also. for example. LT.S. Patent No. 5,254,531 which employs lime along
with an ester oil, a
31 fatty acid, and an amine and EP 271943 which employs lime along with oil.
water. and an
32 ethoxylated amine. The generally accepted role of the reserve alkalinity is
to help maintain the
33 viscosity and stabiiitv of the invert emulsion. This is especially
important in areas in which
CA 02351088 2001-05-11
WO UO/27945 2 PCT/US99/26639
1 acidic gases such as C02 or HZS are encountered during drilling. Absent an
alkaline reserve,
2 acidic gases will weaken stability and viscosity of conventional invert
emulsion fluids to the
3 point of failure. That is to say the invert emulsion becomes so unstable
that the oil wet solids
4 become water wet and the phases of the invert emulsion "flip" thus rendering
the invert
emulsion fluid not suitable for use as a drilling fluid. One of skill in the
art should understand
6 that due to the high cost of removing and disposing of the flipped mud from
a borehole, the
7 formation of flip mud is very undesirable. Further because the beneficial
properties of the
8 drilling fluid have been lost, (i.e. viscosity, pumpability and the ability
to suspend particles) the
9 likelihood of a blowout is greatly increased. Thus, one of ordinary skill in
the art should
to understand that the maintenance of a alkalinity reserve is critical to the
use of conventional
11 invert emulsion drilling fluids and muds.
12 SUMMARY OF THE INVENTION
13 The present invention is generally directed to an invert emulsion drilling
fluid that is
14 formulated so as to have a negative alkalinity as is defined herein. Such
an illustrative fluid
should include: an oleaginous phase; a non-oleaginous phase and an emulsifying
agent capable
16 of stabilizing the invert emulsion under conditions of negative alkalinity.
The oleaginous phase
17 may be mineral oil, synthetic oils, poly-alpha olefins, or esters of C1 to
Clz alcohols and a Cg to
18 C24 monocarboxylic acid, and preferably the ester is selected from C1 to
C12 alkyl alcohol esters
19 of oleic acid, Ci to C12 alkyl alcohol esters of myristic acid, C1 to C12
alkyl alcohol ester of coco
2o fatty acid, and mixtures thereof. The emulsifying agent should be capable
of stabilizing the
2t invert emulsion in the absence of an alkali reserve. That is to say the
addition of an aqueous
22 acidic solution to the invert emulsion should not cause the invert emulsion
to break. The non-
23 oleaginous phase should preferably have an hydroxide ion concentration of
less than 1 x 10'8
24 moles per liter. Optionally the illustrative drilling fluid may include a
weighting agent selected
from barite, calcite, mullite, gallena, manganese oxides, iron oxides, or
combinations thereof.
26 The non-oleaginous phase of the drilling fluid is preferably selected from
aqueous solutions
27 including fresh water, sea water, brine, aqueous solutions containing water
soluble organic salts,
28 water soluble alcohols or water soluble glycols or combinations thereof.
29 Also encompassed within the present invention is a mineral-oil free invert
emulsion
3o drilling fluid which includes an oleaginous phase, a non-oleaginous phase
and an emulsifying
31 agent such that the mineral oil free invert emulsion drilling fluid has
negative alkalinity. The
32 oleaginous phase of this illustrative embodiment may comprise substantially
of esters of CI-Ci2
33 alcohols and Cg-CZa monocarboxylic acids, and preferably the ester is
selected from C1 to C12
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WO 00/27945 ~ PCTIUS99/26639
1 alkyl alcohol esters of oleic acid, C1 to C~2 alkyl alcohol esters of
myristic acid, C~ to C~2 alkyl
2 alcohol ester of coco fatty acid, and mixtures thereof. The non-oleaginous
phase is preferably
3 selected from fresh water, sea water, brine, aqueous solutions containing
water soluble organic
4 salts, water soluble alcohols or water soluble glycols or combinations
thereof. The emulsifying
agent should be in sufficient amounts so as to stabilize an invert emulsion
under conditions of
6 negative alkalinity as is defined herein.
7 Another encompassed embodiment of the present invention is an alkali reserve
free
8 invert emulsion drilling fluid that is formulated so that the drilling fluid
includes: an oleaginous
9 phase which may substantially composed of esters of C1 to C12 alcohols and a
Cg to C2a
to monocarboxylic acid; a non-oleaginous phase and a emulsifying agent capable
of stabilizing the
11 invert emulsion absent an alkali reserve.
12 Further encompassed by the present invention is an invert emulsion drilling
fluid of the
13 present invention the formulation includes: an oleaginous phase comprising
substantially of
14 esters of C~ to C12 alcohols and a Cg to C24 monocarboxylic acid; a non-
oleaginous phase; and
an emulsifying agent capable of stabilizing the invert emulsion in the absence
of an alkali
16 reserve and wherein said fluid is absent an alkaline reserve.
17 Also encompassed within the scope of the present invention are the methods
of making
18 and using the invert emulsion drilling fluids disclosed herein. Thus one
illustrative method
19 embodiment of the present invention includes a method of drilling a
subterranean well with an
2o invert emulsion drilling fluid including: formulating a negative alkalinity
invert emulsion
21 drilling fluid such that the drilling fluid includes, an oleaginous phase,
preferably comprising
22 substantially of esters of C1 to C12 alcohols and a Cg to C24
monocarboxylic acid; a non-
23 oleaginous phase; and an emulsifying agent which is capable of stabilizing
the invert emulsion
24 in the absence of an alkali reserve; and drilling said well with said
invert emulsion drilling fluid.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
26 As used herein, the term "invert emulsion" is an emulsion in which a non-
oleaginous
27 fluid is the discontinuous phase and an oleaginous fluid is the continuous
phase. The novel
28 invert emulsion fluids of the present invention are useful in a similar
manner as conventional
29 invert emulsion fluids which includes utility in preparation for drilling,
drilling, completing and
3o working over subterranean wells such as oil and gas wells. Such methods of
use of
31 conventional inverse emulsion fluids are described in, for example,
Composition and Properties
32 of Drilling and Completion Fluids, 5th Edition, H. C. H. Darley, George R.
Gray, Gulf
33 Publishing Company, 1988, the contents which are incorporated by reference,
as well as, U.S.
CA 02351088 2001-05-11
WO 00!27945 4 PCT/US99/26639
i Patent No. 5,254,531 and EP 271943 which are incorporated by referenice. One
of skill in the art
2 should know and understand the standard methods of determining if an invert
emulsion has been
3 formed. Examples of two such tests for the formation of an invert emulsion
include the Invert
4 Emulsion Test as disclosed herein and the measurement of the electrical
stability of the invert
emulsion.
s As used herein the term "alkalinity" means a presence of an alkaline reserve
as is
7 measured using the methods setforth in API Bulletin RP 13B-2, 1990, which
describes a
8 standard test for determining excess lime in drilling mud, the contents of
which are hereby
9 incorporated by reference.
to As used herein the terms "negative alkalinity" or "negative alkaline
reserve" mean an
l i the absence of an alkaline reserve or that condition of the invert
emulsion which would require
12 the addition of alkaline reserve material so as to establish a measurable
value of alkalinity. That
i3 is to say one of skill in the art would consider the invert emulsion to be
acidic in nature and thus
14 require the addition of sufficient alkaline reserve material to neutralize
any acidic components
present as well to establish the desired alkaline reserve. Alternatively
negative alkalinity or
is negative alkaline reserve may be considered as being that state of an
invert emulsion drilling
17 fluid in which the non-oleaginous phase has a hydroxide ion (OH-)
concentration of less than 1
i 8 x 10'7 moles per liter and more preferably a hydroxide ion concentration
of less than 1 x 10-8
19 moles per liter. One of ordinary skill in the art should understand that a
hydroxide ion
2o concentration of 1 x 10-8 may be expressed as a pOH value of 8 which in
aqueous solution
21 corresponds to a pH of 5. The hydroxide ion concentration may be tested by
separating the two
2z phases, for example by allowing the emulsion to separate over the course of
several days to
23 weeks, and then carefully measuring the hydroxide ion concentration of the
non-oleaginous
24 phase by conventional means which should be known to one of skill in the
art.
As used herein the term "oleaginous liquid" means an oil which is a liquid at
25°C and
26 immiscible with water. Oleaginous liquids typically include substances such
as diesel oil,
27 mineral oil, synthetic oil, ester oils, glycerides of fatty acids,
aliphatic esters, aliphatic ethers,
2s aliphatic acetals, or other such hydrocarbons and combinations of these
fluids. In one
z9 illustrative embodiment of this invention the oleaginous liquid is an ester
material which
3o provides environmental compatibility to the overall drilling fluid. Such
esters are described in
31 greater detail below.
32 The amount of oleaginous liquid in the invert emulsion fluid may vary
depending upon
33 the particular oleaginous fluid used, the particular non-oleaginous fluid
used, and the particular
CA 02351088 2001-05-11
WO 00/27945 PCT/US99/26639
1 application in which the invert emulsion fluid is to be employed. However,
generally the
2 amount of oleaginous liquid must be sufficient to form a stable emulsion
when utilized as the
3 continuous phase. Typically, the amount of oleaginous liquid is at least
about 30, preferably at
4 least about 40, more preferably at least about 50 percent by volume of the
total fluid.
As used herein, the term "non-oleaginous liquid" mean any substance which is a
liquid
b at 2S°C and which is not an oleaginous liquid as defined above. Non-
oleaginous liquids are
7 immiscible with oleaginous liquids but capable of forming emulsions
therewith. Typical non-
8 oleaginous liquids include aqueous substances such as fresh water, sea
water, brine containing
9 inorganic or organic dissolved salts, aqueous solutions containing water-
miscible organic
io compounds and mixtures of these. In one illustrative embodiment the non-
oleaginous fluid is
1 i brine solution including inorganic salts such as calcium halide salts,
zinc halide salts, alkali
12 metal halide salts and the like.
13 The amount of non-oleaginous liquid in the invert emulsion fluid may vary
depending
i4 upon the particular non-oleaginous fluid used and the particular
application in which the invert
emulsion fluid is to be employed. Typically, the amount of non-oleaginous
liquid is at least
16 about l, preferably at least about 3, more preferably at least about S
percent by volume of the
17 total fluid. Correspondingly, the amount should not be so great that it
cannot be dispersed in the
i8 oleaginous phase. Therefore, typically the amount of non-oleaginous liquid
is less than about
19 90, preferably less than about 80, more preferably less than about 70
percent by volume of the
2o total fluid.
21 As the term is used herein, the term "surfactant" and "emulsifier" or
"emulsifying agent"
z2 are used interchangeably to indicate that component of the invert emulsion
drilling fluid that
23 stabilizes the invert emulsion. One of ordinary skill in the art should
appreciate that such a
24 compound acts at the interface of the oleaginous and the non-oleaginous
fluids and lowers the
differences in surface tension between the two layers. In the present
invention it is important
z6 that the emulsifying agent is not adversely affected by the presence of
acid in the non-
27 oleaginous component of the invert emulsion. The ability of any particular
emulsifying agent to
28 stabilize the invert emulsion can be tested by using the invert emulsion
test disclosed below. In
29 addition if the emulsifying agent is to be useful in the formulation of a
drilling fluid, the
3o emulsifier should be thermally stable. That is to say, the emulsifier must
not break down or
31 chemically degrade upon heating to temperatures typically found in a
downhole environment.
32 This may be tested by heat aging the emulsifier as is done in the Examples.
A suitable
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WO 00127945 PCTNS99/Z6639
1 emulsifier within the scope of the present invention should be capable of
stabilizing the invert
2 emulsion under conditions of negative alkalinity and heat aging.
3 In one preferred embodiment of the present invention, the emulsifying agent
is a
4 combination of an amidoamine primary emulsifier, such as a diethylene
triamine fatty acid,
commercially available as Ecogreen-P from M-I L.L.C., a fatty acid based
secondary emulsifier,
6 such as a tall oil fatty acid, commercially available as Ecogreen-S from M-I
L.L.C. and a
7 polymeric fluid Ioss control agent, such as a oil dispersible polystyrene
butdiene copolymer,
s commercially available as Ecogreen-F from M-I L.L.C. One of skill in the art
should
9 understand that the selection of this combination of specific emulsifiers is
but one of many
to possible combinations of emulsifiers having similar properties and
characteristics. The process
11 of testing any particular selection of a suitable emulsifier or emulsifier
package may depend
12 upon the conditions and components of the drilling fluids and thus the use
of the Invert
13 Emulsion test disclosed herein should be utilized.
14 In another embodiment of the present invention the emulsifying agent is a
protonated
amine. As used herein, the term "amine" refers to compounds having the
structure R-NH2
16 wherein R represents a C~2-C22 alkyl group, a C12-C22 alkenyl group, a C3-
Cg cycloalkyl group
17 substituted with a C9-C14 alkyl or alkenyl group, or a C9-C;4 alkyl or
alkenyl group substituted
18 with a C3-C8 cycloalkyl group. Preferable R groups include straight or
branched dodecyl,
19 tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,
nodecyl, eicosyl, heneicosyl,
2o docosyl; as well as, mixtures and unsaturated derivatives thereof.
Preferable unsaturated
21 derivatives include soyaalkylamine (Armeen STM available from Akzo
Chemicals Inc.} and
22 tallowalkylamine (Armeen TTM available from Akzo Chemicals Inc.}. Many of
the other above
23 amines are also commercially available from Akzo Chemicals Inc. under the
tradename
24 ArmeenTM. Other oleophillic amines may be used in the practice of the
present invention so
long as their protonated salt stabilizes the invert emulsion. Such amines can
be determined by
26 one of ordinary skill in the art by trial and error testing of the
protonated amine and its ability to
2~ form a stable invert emulsion under conditions of negative alkalinity.
28 The aforementioned amines of the formula R-NH2 are protonated for use in
the present
29 invention. The term "protonated" means that the amine is converted to the
structure R-N+-H3
B'. Typically, such protonation occurs due to reaction of the amine with a
water-soluble acid as
31 discussed below. Generally, the type of counter-ion, B-, is not
particularly critical so long as it
32 does not adversely affect the performance and characteristics of the
resulting emulsion as is
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WO 00127945. PCTIUS99/26639
1 disclosed herein. Examples of the counter-ion include the conjugate bases of
the acids
2 described below.
3 The protonated amine functions in the instant invention as a surfactant to
lower the
4 interfacial tension of the liquids so that the non-oleaginous liquid may
form a stable dispersion
of fine droplets in the oleaginous liquid (i.e. form an invert emulsion).
Therefore, the amount of
6 protonated amine should be sufficient to enable the formation of an invert
emulsion. While this
amount may vary depending upon the nature and amount of the oleaginous liquid
and non
8 oleaginous liquid, typically the amount of protonated amine is at least
about 0. l, preferably at
9 least about 5, more preferably at least about 10 percent by weight to volume
of the total fluid.
to Correspondingly, the amount should not be so great that the protonated
amine interferes with
11 the stability of the invert emulsion fluid or the performance of the invert
emulsion as a drilling
12 fluid.
13 As used above, the term "acid" refers to water-soluble, i.e. at least 10
percent by volume
14 of the acid dissolves in water; compounds which form "acidic solutions". A
solution is
considered to be an "acidic solution" if it is capable of protonating the
amine and render a stable
16 non-oleaginous fluid in oleaginous fluid emulsion. The term acid refers to
both inorganic acids
I7 such as sulfuric, nitric, hydrofluoric, hydrochloric and phosphoric acid
and organic acids such as
Z 8 citric, acetic, formic, benzoic, salicyclic, oxalic, glycolic, lactic,
glutaric acid, halogenated acetic
19 acids, boric acid, organosulfonic acids, organophosphoric acids and the
Like. Fatty acids such as
oleic, palmitic, and stearic acid are less desirable as acids because such
acids are not water-
21 soluble. Compounds that generate acidic solutions upon dissolution in water
are also considered
22 "acids" as the term is used herein. For example such acids may include,
acetic anhydride,
23 hydrolyzable esters, hydrolyzable organosulfonic acid derivatives,
hydrolyzable
24 organophosphoric acid derivatives, phosphorus trihaiide, phosphorous
oxyhalide, acidic metal
salts, sulfur dioxide, nitrogen oxides, carbon dioxide, and similar such
compounds. Thus in one
26 embodiment, the acidic solution is formed by the dissolution of an acidic
metal salt in water.
27 That is to say the upon dissolution of the metal salt, a sufficient
concentration of protons are
28 produced the resulting solution is capable of protonating the amine and
render a stable non-
29 oleaginous fluid in oleaginous fluid emulsion. In another embodiment the
acidic solution is a
3o brine formed by the dissolution of a neutral metal salt and an acidic metal
salt in water. In yet
31 another embodiment, an acidic solution may be formed by the dissolution of
a acid compound
32 and a neutral salt.
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i When an amine surfactant is present, the amount of acid must be sufficient
to protonate a
2 majority of the amine thus making it capable of stabilizing the invert
emulsion under conditions
3 of negative alkalinity. As one skilled in the art should appreciate, the
amount of acid will
4 necessarily vary with the strength of the acid and the particular amine to
be protonated.
Nevertheless, one skilled in the art having the benefit of this specification
may readily
6 determine the necessary amount of acid via routine experimentation by
systematically adjusting
7 the amount and type of acid to be used with any particular amine and then
testing to see if the
8 resulting protonated amine is capable of forming and stabilizing an invert
emulsion.
9 As used herein the term "ester" has been used in relation to the oleaginous
fluid
component of the invert emulsions of the present invention. Such use of the
term "ester" should
11 be broadly construed to include all esters that are suitable for use in
drilling fluids. In one
12 preferred embodiment, the term "ester" generally includes esters formed in
the esterification
13 reaction of a C, to C12 alcohol and a Cg to C24 monocarboxylic acid.
Optionally the ester may
14 be the product of the esterification reaction between a CI to Clz alcohol
and a C4 to C12
polycarboxylic acid. An illustrative example of a poly-functional carboxylic
acid may be
16 succinic acid which would form a di-ester in the esterification reaction
with a C1 to C12 alcohol.
17 The esters suitable for use in the present invention should be oleaginous
and capable of
i 8 forming invert emulsion with water or other aqueous based fluids. In
addition the esters which
19 may be utilized in the present invention may be broadly selected from
esters formed from C1-
2o C 12 alcohols and mono-functional or poly-functional carboxylic acids, so
long as the ester flow
21 and can be pumped at temperatures in the range from about 0° to
about 25° C. Such esters
22 should also be selected so that the flash point of the ester does not
create a combustion hazard
23 on the drilling rig. Therefore the esters of the present invention should
be selected so as to have
24 a flash point greater than about 100° F and preferably a flash point
greater than about 130° F. In
one preferred embodiment the flash point of the ester is in the range from
about 125° F to about
26 .150° F. Another property of the esters of the present invention is
that of viscosity. The ester
27 should be selected so that it has a viscosity that is suitable for use in a
drilling fluid. Preferably
28 the viscosity should be less than about 1 S centistokes at about 100
° C and more preferably less
29 than about 10 centistokes at about 100 ° C.
3o Esters which may be utilized in the practice of the present invention do
not show the
31 same in-use behavior as the ester based drilling fluids reported prior to
the present invention. In
32 practical application, the esters of C1 to C12 alcohol and Cg to C24
monocarboxylic acid undergo
33 hydrolysis in the presence of hydroxide ion (OH'), resulting in the
formation of the
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WO 00/27945 PCTIUS99/26639
1 corresponding alcohol and carboxylic acid. The formation of acid in
conventional ester based
2 drilling fluid is of great concern because such fluids have an alkaline
reserve which is
3 chemically neutralized by the acids thus destabilizing the invert emulsion
drilling fluid. Further
4 the acid in the presence of lime may form a calcium soap which further
promotes the adverse
effect on rheology of the invert emulsion. The hydrolysis reaction is reported
to be the primary
6 reason for the careful selection of esters that are either thermodynamically
or kinetically stable
7 with regard to the hydrolysis reaction. Another reported approach has been
the addition of
8 amine compounds in combination with a mild alkaline reserve. The role of the
amine
9 compound is to preferentially react with the acids generated by the
hydrolysis reaction. Thus,
to the amine compound serves as a "buffer" for the alkaline reserve and
prevents it's consumption
i i by the fatty acids generated by the hydrolysis reaction.
12 The above is in contrast with the teachings of the present invention in
which an invert
13 emulsion drilling fluid may be based on ester oils despite the difficulties
of hydrolysis inherent
14 in the use of ester based materials in a conventional ester based invert
emulsion drilling fluid.
In particular it is believed that the negative alkalinity of the invert
emulsion drilling fluids of the
16 present invention greatly reduces the hydrolysis reaction. Further the
presence of carboxylic
17 acid has no deleterious effect on the protonated amine surfactant which
stabilizes the invert
i8 emulsion. Thus rather than reducing the rate of hydrolysis by the careful
selection of the ester
19 or providing an alkaline reserve "buffer", the present invention greatly
reduces the hydrolysis of
2o the ester by substantially eliminating the source of hydroxide ion, i.e.
the alkaline reserve.
21 As already stated, the choice of esters which may be utilized in the
invention disclosed
22 herein may be selected from the general class of reaction products of
monofunctional carboxylic
23 acids with monofunctional alcohols. In addition, however, it is intended in
accordance with the
24 invention to at least predominantly to use C8-C24 carboxylic acids. The
carboxylic acids may be
derived from unbranched or branched hydrocarbon chains; preferably linear
chains and may be
26 saturated, monounsaturated or polyunsatutrated. Selected individual esters
formed from an
z7 alkyl monocarboxylic acid and a monoalcohol can be used as the ester oil in
accordance with
28 the invention. Sa far as the rheology of the system is concerned and/or for
reasons of
29 availability, it is frequently desirable to use esters from acid mixtures.
This is of importance so
3o far as meeting the above-stated specifications of the two-classes for
preferred ester oils is
31 concerned.
32 Economically the selection of the ester utilized in the present invention
becomes very
33 important because the present invention allows the use of primary alcohol
esters and secondary
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1 alcohol esters which previously had a limited application due to their rapid
rate of hydrolysis in
2 the presence of hydroxide ion. Thus the selection of the alcohol portion of
the esters utilized in .
3 the present invention may be based on economic considerations of cost and
availability and not
4 necessarily on the rate of hydrolysis of the ester. Tn view of the teaching
of the present
disclosure, one of skill in the art should understand that the broad group of
CI-C12 alcohols
6 includes alcohols selected from: primary alkyl alcohols such as for example,
methanol, ethanol,
7 n-propanol, n-butanol, n-pentanol, and the like, branched primary alcohols
such as 2-
8 methylpropan-1-ol. 2,2-dimethylpropan-1-ol, 2,2-dimethylbutan-I-ol, 3,3-
dimethyl butan-1-of
9 and the like; secondary alkyl alcahols and tertiary alkyl alcohols as well
as unsaturated alcohols
to which previously have not be used due to the problems with hydrolysis due
to the presence of
~ i an alkaline reserve.
12 Upon review of the present disclosure, one of skill in the art should
appreciate that esters
13 of the present invention may be preferably selected from: C~ to C12 alkyl
alcohol esters of oleic
14 acid, Ci to C12 alkyl alcohol esters of myristic acid, C1 to C12 alkyl
alcohol ester of coco fatty
acid, combinations and mixtures thereof. More preferably, esters which afford
especially high
16 economic cost savings and thus are more preferred include: oleate methyl
ester, isopropyl
t7 meristate ester, methyl ester of coco fatty acid. However the selection of
any particular ester, as
is previously noted may depend upon availability and economic considerations
such as cost.
19 Various supplemental surfactants and wetting agents conventionally used in
invert
2o emulsion fluids may optionally be incorporated in the fluids of this
invention. Such surfactants
2t are, for example, fatty acids, soaps of fatty acids, amido amines,
polyamides, polyamines, oleate
22 esters, imidazoline derivatives, oxidized crude tall oil, organic phosphate
esters, alkyl aromatic
23 sulfates and sulfonates, as well as, mixtures of the above. Generally, such
surfactants are
24 employed in an amount which does not interfere with the fluids of this
invention being used as
drilling fluids.
26 Viscosifying agents; for example, organophillic clays, may optionally be
employed in
27 the invert drilling fluid compositions of the present invention. Usually,
other viscosifying
28 agents, such as oil soluble polymers, polyamide resins, polycarboxylic
acids and fatty acid soaps
29 may also be employed. The amount of viscosifying agent used in the
composition will
necessarily vary depending upon the end use of the composition. Usually such
viscosifying
31 agents are employed in an amount which is at least about 0.1, preferably at
least about 2, more
32 preferably at least about 5 percent by weight to volume of the total fluid.
VG-69TM and VG-
CA 02351088 2001-05-11
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WO OOI27945 PCT/US99I26639
1 PLUSTM are organoclay materials and Versa HRPTM is a polyamide resin
material manufactured
2 and distributed by M-I L.L.C. which are suitable viscosifying agents.
3 The invert emulsion drilling fluids of this invention may optionally contain
a weight
material. The quantity and nature of the weight material depends upon the
desired density and
viscosity of the final composition. The preferred weight materials include,
but are not limited
6 to, barite, calcite, mullite, gallena, manganese oxides, iron oxides,
mixtures of these and the
7 like. The weight material is typically added in order to obtain a drilling
fluid density of less
8 than about 24, preferably less than about 2I, and most preferably less than
about 19.5 pounds
9 per gallon.
to Fluid loss control agents such as modified lignite, polymers, oxidized
asphalt and
l 1 gilsonite may also be added to the invert drilling fluids of this
invention. Usually such fluid loss
12 control agents are employed in an amount which is at least about 4.1,
preferably at least about 1,
13 more preferably at least about 5 percent by weight to volume of the total
fluid.
14 The method of preparing the drilling fluids of the present invention is not
particularly
critical so long as an invert emulsion is formed under conditions of negative
alkalinity.
16 Generally, the components rnay be mixed together in any order under
agitation condition.
17 When an amine surfactant is used, it is important that the amine surfactant
be protonated for the
Is formation of invert emulsion with the oleaginous and non-oleaginous fluids.
A representative
19 method of preparing said invert emulsion fluids comprises mixing an
appropriate quantity of
oleaginous fluid and an appropriate quantity of surfactant together with
continuous, mild
21 agitation. A non-oleaginous fluid is then added while mixing until an
invert emulsion is
22 formed. If weight material, such as those described below; are to be added,
then the weight
23 material is typically added after the invert emulsion fluid is formed.
24 One skilled in the art may readily identify whether the appropriate
ingredients and
amounts have been used to form an invert emulsion by using the following test:
26 INVERT EMULSION TEST: A small portion of the emulsion is placed in a beaker
which
27 contains an oleaginous fluid. If the emulsion is an invert emulsion, the
small portion of the
28 emulsion will disperse in the oleaginous fluid. Visual inspection will
determine if it has so
29 dispersed.
Alternatively, the electrical stability of the invert emulsion may be tested
using a typical
31 emulsion stability tester. Generally the voltage applied across two
electrodes is increased until
32 the emulsion breaks and a surge of current flows between the two
electrodes. The voltage
33 required to break the emulsion is a common measure of the stability of such
an emulsion. Other
CA 02351088 2001-05-11
12
WO 00/27945 PCTIUS99/26639
1 tests are described on page 166 of the book, Composition and Properties of
Drilling and
2 Completion Fluids, 5th Edition, H. C. H. Darley and George Gray, Gulf
Publishing Company,
3 1988, the contents of which are hereby incorporated by reference.
4 The following examples are included to demonstrate preferred embodiments of
the
invention. It should be appreciated by those of skill in the art that the
techniques disclosed in
6 the examples which follow represent techniques discovered by the inventors
to function well in
7 the practice of the invention, and thus can be considered to constitute
preferred modes for its
8 practice. However, those of skill in the art should, in light of the present
disclosure, appreciate
9 that many changes can be made in the specific embodiments which are
disclosed and still obtain
to a like or similar result without departing from the scope of the invention.
11 The following examples are submitted for the purpose of illustrating the
performance
12 characteristics of the drilling fluid compositions of this invention. These
tests were conducted
13 substantially in accordance with the procedures in API Bulletin RP I3B-2,
1990 which is
14 incorporated herein by reference. The following abbreviations may be used
in describing the
is results of experimentation:
16 "E.S." is electrical stability of the emulsion as measured by the test
described in
17 Composition and Properties of Drillin,~ and Completion Fluids, 5th Edition,
H. C. H. Darley,
is George R. Gray, Gulf Publishing Company, 1988, pp. 116, the contents of
which are hereby
19 incorporated by reference. Generally, the higher the number, the more
stable the emulsion.
20 "PV" is plastic viscosity which is one variable used in the calculation of
viscosity
21 characteristics of a drilling fluid, measured in centipoise {cp) units.
22 "YP" is yield point which is another variable used in the calculation of
viscosity
23 characteristics of drilling fluids, measured in pounds per 100 square feet
(ib/100ftz).
24 "AV" is apparent viscosity which is another variable used in the
calculation of viscosity
25 characteristic of drilling fluid, measured in centipoise (cp} units.
26 "GELS" is a measure of the suspending characteristics, or the thixotropic
properties of a
27 drilling fluid, measured in pounds per 100 square feet (lb/100 ft2).
28 "API F.L." is the term used for API filtrate loss in milliliters (ml).
29 "HTHP" is the term used for high temperature high pressure fluid loss at
200°F,
30 measured in milliliters {ml) according to API bulletin RP 13 B-2, 1990.
31 As used in the formulation of the drilling fluids illustrated in the
following example the
32 following component names are intended to mean the following:
33 Finagreen BDMF~ is fatty acid ester distributed by FTNA chemicals.
CA 02351088 2001-05-11
13
WO 00/27945 PCTNS99I26639
1 Ecogreen-P~ is a primary surfactant package distributed by M-I L.L.C.
2 Ecogreen-S~ is a secondary surfactant package distributed by M-I L.L.C.
3 Ecogreen-F~ is a polymeric fluid loss control agent distributed by M-I
L.L.C.
4 isopropyl meristate ester is fatty acid ester obtained from R I T A
chemicals.
CoCo fatty acid methyl ester is obtained from FINA Chemicals.
6 Oleate methyl ester was obtained from FINA Chemicals.
7 VERSALIG is fluid loss control agent distributed by M-I L.L.C.
8 NOVATHIN is surfactant distributed by M-I L.L.C.
9 EMI-545 is a protonated amine acetate surfactant of the present invention
which is
to distributed by M-I L.L.C.
11 NOVAWET is surfactant distributed by M-I
12 All values associated with the formulations described below are grams
unless otherwise
13 specified.
14 EXAMPLE 1
Two invert emulsions having a density of about 12.5 pounds per gallon and an
oil to
16 water ratio of about 85:15 were formulated as indicated below, the first
with a alkaline reserve
17 (lime) and the second not having an alkaline reserve:
18
Formulation: _1 2
Finagreen BDMF 194 i 94
Lime 3.5 0
VG-Plus 3 3
Ecogreen-P 6 6
Ecogreen-S 2 2
Ecogreen-F 1 1
EMI 545 0 6
20% CaCl2 Brine 54 54
Barite 258 258
Acetic Acid - 1 ml
19
2o Samples of the above invert emulsions were heat aged at 250° F far
16 hours. The
21 Theological properties of the resulting fluids are given below:
22
CA 02351088 2001-05-11
14
WO 00/27945 PCTIUS99/26639
Heat Aged for 16 H at 250° F
Formulation 1 2
(lime) (no lime)
PV * 32
YP * 9
Gels 10 sec. * 5
min. * 8
ES * 923
1 *sample too thick to measure
2
3 One of ordinary skill in the art should appreciate upon review of the above
data that the
4 invert emulsion fluid conventionally formulated and containing lime (Formula
1) was to thick to
5 measure after heat aging and thus would not be suitable for use a an invert
emulsion drilling
6 fluid. In contrast the invert emulsion drilling fluid formulated in
accordance with the present
invention exhibits properties of a invert emulsion that is suitable for use in
drilling operations.
8
9 A sample of the invert emulsion drilling fluid formulated in accordance with
the present
l0 invention (Formula 2) was heat aged at various temperatures to illustrate
the wide range of
11 temperatures which can be withstood by the formulation. Such data is
presented below:
12
Heat Aged Heat Aged for
for
l6Hat250F l6Hat2'75F
Formulation: 2 2
(no Lime) (no lime)
PV 32 31
YP 9 10
Gels 10 sec. 5 7
10 min. 8 10
ES 923 589
13
Heat Aged Heat Aged for
for
l6Hat300F l6Hat350
Formulation: 2 2
(no lime) (no lime)
PV 33 33
YP 6 15
Gels 10 sec. 7 8
10 min. 10 12
ES 687 900
HTHP 4.8
14
15Upon review of
the above data,
one of ordinary
skill in the
art should understand
that the
16invert emulsion ng fluid
drilli formulated
in accordance
with the
present
invention
retains
the
1~properties necessaryfor its an invert emulsion drilling fluid at
use as a wide range of
18temperatures.
CA 02351088 2001-05-11
wo oor~~9as 15
PCT/US99126639
1 The above drilling fluids after heat aging at 250° F for 16 hours
were analyzed for
2 alcohol in the fluid. The % alcohol indicates the extent of the hydrolysis
of the ester component
3 of the invert emulsion fluid.
4
Formulation Alcohol Content
I (lime) 6.0%
2 (no lime) 0.1%
6 The above results indicated that the Finagreen BDMF fluid with reserve
alkalinity had
7 much higher hydrolysis than the fluid of this invention with negative
alkalinity. Also, the
s results of heat aging indicated that the fluids with negative alkalinity are
stable in excess of 350°
9 F.
11 EXAMPLE 2
12 The following invert emulsion fluids were formulated so as to give invert
emulsions
13 having a 12.5 pound per gallon density and an oil to water ratio of 85:15
as indicated below, the
14 first with an alkaline reserve the second absent an alkaline reserve:
Formulation _3 _4
isopropyl meristate-ester194 194
Lime 3.5 0
Gel 3 3
Ecogreen-P 6 6
Ecogreen-S 2 2
Ecogreen-F I 1
EMI 545 0 6
20% CaCl2 Brine 54 54
Barite 258 258
Acetic Acid - 1 ml
16
I7 The rheological properties of the resulting invert emulsion were measured
both before
18 and after heat aging and gave the following results:
19
Heat Aged for 16 h at Heat Aged for 16 h at 275°
2S0 F F
Formulation 3 4 3 4
(lime)(no lime) (lime) (no lime)
PV 28 21 34 22
YP 11 7 7 4
Gels 10 sec. 9 5 S 4
10 min. 13 9 10 7
ES 600 968 223 553
HTHP
CA 02351088 2001-05-11
WO 00/27945 16 PCT/US99I26639
Heat Aged for 16 h at 300° F Heat Aged for 16 h at 325°
F
Formulation 3 4 3 4
(lime) (no lime) (lime) (no lime)
PV 58 22 61 21
YP 22 5 69 14
Gels 10 sec. 11 4 35 5
min. 19 7 41 11
ES 323 387 328 503
HTHP 4.4
1
2 The above drilling fluids with isopropyl-meristate ester were analyzed for %
alcohol
3 content in the fluid after heat aging at 300° F. The % alcohol
content serves as an indication of
4 extent of the hydrolysis of the ester. The following results were obtained:
5
Formulation Alcohol Content
3 Lime 2
4 No Lime 0.1
6
7 The above results indicate that the fluid with reserve alkalinity has higher
% hydrolysis
8 than the fluid with negative alkalinity as is defined herein. Also, the
fluids with negative
9 alkalinity of this invention are stable in the excess of 325° F heat
aging cycle.
11 EXAMPLE 3
12 The following invert emulsion drilling fluid was formulated utilizing a
methyl ester of
13 CoCo Fatty Acid to give an invert emulsion with an oil to water ratio of
85:15 and a density of
14 12.5 pounds per gallon as follows:
Formulation _S
Methyl Ester of CoCo Fatty Acid194
Lime 0
Gel 3
Ecogreen-P 6
Ecogreen-S 2
Ecogreen-F 1
EMI 545 6
20% CaCl2 Brine 54
Barite 258
Acetic Acid 1 ml
16
17 The rheological properties
of the resulting invert emulsion
were measured both prior to
I8 and after heat aging giving the following results:
19
CA 02351088 2001-05-11
WO 00/27945 17
PCTIUS99/2b639
Initial Heat Aged for Heat Aged
for
l6hat250F l6hat300F
PV 14 15 I7
YP 9 5 9
Gels 10 sec. 8 5 7
min. 11 8 9
ES 285 780 999
HTHP 10.4
1
2 The above formulation after heat aging at 300° F showed 0.1% alcohol
content in the
3 fluid indicating the stability of the fluid in excess of 300° F with
negative alkalinity of this
4 invention.
5
6 EXAMPLE 4
7 The following invert emulsion that is illustrative of the present invention
was
8 formulated:
9
Formulation _b
methyl oieate 186
VG PLUS 2
Ecogreen-P 6
Ecogreen-S 2
Ecogreen-F 2
Acetic Acid 1 ml
EMI-545 6
20% CaCl2 Brine 68
barite 231
11 The above components were mixed to form the invert emulsion in the
following manner:
12 a) the ester and VGPLUS were mixed together for i0 minutes; b) to this
mixture the Ecogreen-
13 P, Ecogreen-S, Ecogreen -F, acetic acid and EMI-545 were added and mixed
for an additional
14 10 minutes; c) the brine was added with mixing and upon complete addition
the mixing was
continued for an additional 30 minutes to form an invert emulsion; d) the
weight material
16 (barite) was added and the fully formulated invert emulsion mud was stirred
for an additional 10
17 minutes. The resulting invert emulsion drilling mud was found to have the
following properties
18 before and after heat aging at different temperatures:
19
CA 02351088 2001-05-11
Ig
WO 00/27945 PCTIUS99/26639
Initial Heat Aged at Heat Aged at Heat Aged at
200°F for 16 h 250°F for 16 h 300°F for 16 h
PV 30 29 30 30
YP 10 17 20 14
Gels 10 sec. 10 13 12 7
min. 1 S 23 18 I 0
ES 1078 361 711 1443
HTHP 6 2.8 1.6
1
2 Upon review of the above data, one of skill in the art should appreciate
that the fluid
3 formulated in accordance with this invention is stable and retains the
properties of a useful
4 invert emulsion drilling mud even after heat aging in excess of
300°F. Further it will be noted
5 that there is no lime or other alkaline reserve present in the formulation
and thus the invert
6 emulsion drilling fluid is considered to posses negative alkalinity as the
term is used in the
7 present disclosure.
8
9 EXAMPLE 5
to The following invert emulsion that is illustrative of the conventional
manner of making
11 invert emulsion drilling fluids was formulated:
12
Formulation 7
methyl oleate 186
Lime 3.5
VG PLUS 2
Ecogreen-P 6
Ecogreen -S 2
Ecogreen F 2
20% CaClz Brine 68
Barite 231
13
14 The above components were mixed to form the invert emulsion in the
following manner:
a) the ester, lime and VGPLUS were mixed together for 10 minutes; b) to this
mixture the
16 Ecogreen-P, Ecogreen-S, Ecogreen -F, were added and mixed for an additional
10 minutes; c)
17 the brine was added with mixing and upon complete addition the mixing was
continued for an
I8 additional 30 minutes to form an invert emulsion; d) the weight material
(barite) was added and
19 the fully formulated invert emulsion mud was stirred for an additional 10
minutes. The
resulting invert emulsion drilling mud was found to have the following
properties before and
21 after heat aging at different temperatures:
22
CA 02351088 2001-05-11
19
WO 00/27945 PCTlUS99/26639
Initial Heat Aged Heat Aged Heat Aged
at at at
200F for 16 250F for 300F for
h 16 h 16 h
PV 33 70 37 50
YP 29 106 25 28
Gels 10 sec. 13 69 12 15
min. 18 80 15 16
ES 1171 330 260 875
HTHP - 2.8 2.4 5.2
1
z Upon review of the above results one of ordinary skill in the art should
appreciate that
3 that an ester containing invert emulsion drilling fluid with excess
alkalinity results in the
4 hydrolysis of the ester and that upon heat aging at 200°F the
resulting mixture is not considered
5 especially useful as a drilling fluid..
6
7 EXAMPLE 6
8 The following invert emulsion that is illustrative of the present invention
was
9 formulated:
to
Formulation _8
methyl oleate 186
VG PLUS 2
VERSACOAT 6
VERSAWET 2
Ecogreen-F 2
Acetic Acid 1 ml
EMI-545 6
20% CaClz Brine 68
Barite 231
11
12 The above components were mixed to form the invert emulsion in the
following manner:
13 a) the ester and VGPLUS were mixed together for 10 minutes; b) to this
mixture the
14 VERSACOAT, VERSAWET, Ecogreen -F, acetic acid and EMI-545 were added and
mixed for
an additional 10 minutes; c) the brine was added with mixing and upon complete
addition the
16 mixing was continued for an additional 30 minutes to form an invert
emulsion; d) the weight
i7 material (barite) was added and the fully formulated invert emulsion mud
was stirred for an
18 additional 10 minutes. The resulting invert emulsion drilling mud was found
to have the
19 following properties before and after heat aging at different temperatures:
zo
CA 02351088 2001-05-11
WO 00127945 2~ PCT/US99/26639
Initial Heat Aged Heat Aged Heat Aged
at at at
200F for 250F for 16 300F for
16 h h i 6 h
PV 29 28 32 31
YP 14 17 19 11
Gels 10 sec. 15 12 11 7
min. 37 17 18 8
ES 1257 875 875 1148
HTHP - 6 2 2.4
1
2 Upon review of the above data one of ordinary skill in the art should
appreciate that the
3 above noted invert emulsion drilling fluid formulated in accordance with the
present invention
4 is stable and useful as a drilling fluid even after being heat aged at
temperatures up to 300°C.
5 This is in contrast to the invert emulsion drilling fluid in Example 6 in
which the presence of an
6 alkaline reserve cause the break down and premature aging of the invert
emulsion fluid.
7
8 EXAMPLE 7
9 The following invert emulsion that is illustrative of the present invention
was
to formulated:
ii
Formulation 9
methyl oleate 186
VG PLUS 2
Ecogreen-P ~ 6
Ecogreen-S 2
Ecogreen-F 2
NOVAWET 2
Acetic Acid 1 ml
EMI-545 6
20% CaCl2 Brine 68
Barite 231
12
13 The above components were mixed to form the invert emulsion in the
following manner:
14 a) the ester and VGPLUS were mixed together for 10 minutes; b) to this
mixture the Ecogreen -
P, Ecogreen-S, Ecogreen -F, NOVAWET, acetic acid and EMI-545 were added and
mixed for
16 an additional 10 minutes; c) the brine was added with mixing and upon
complete addition the
17 mixing was continued for an additional 30 minutes to form an invert
emulsion; d) the weight
18 material (barite) was added and the fully formulated invert emulsion mud
was stirred for an
19 additional 10 minutes. The resulting invert emulsion drilling mud was found
to have the
following properties before and after heat aging at different temperatures:
21
CA 02351088 2001-05-11
21
WO 00127945 PCT/US99/26639
Initial Heat Aged at Heat Aged Heat Aged
200 at 250 at 300
Fforl6h Fforl6h Fforl6h
PV 24 16 27 28
YP 7 I4 12 15
Gels IO sec. 10 12 10 10
IO min. 13 16 13 13
ES 712 867 719 618
HTHP - 6.8 4.8 2.4
1
2 Upon review of the above data one of ordinary skill in the art should
appreciate that the
3 above noted invert emulsion drilling fluid formulated in accordance with the
present invention
4 is stable and useful as a drilling fluid even after being heat aged at
temperatures up to 300°C.
This is in contrast to the invert emulsion drilling fluid in Example 6 in
which the presence of an
6 alkaline reserve cause the break down and premature aging of the invert
emulsion fluid.
7
s EXAMPLE 8
9 The following invert emulsion that is illustrative of the present invention
was
l0 formulated:
11
Formulation _10
methyl oleate 186
VG PLUS 2
Ecogreen-P 6
Ecogreen-S 2
Ecogreen-F 2
Acetic Acid 0 ml
EMI-545 3
20% CaClz Brine 68
Barite 231
12
13 The above components were mixed to form the invert emulsion in the
following manner:
14 a) the ester and VGPLUS were mixed together for 10 minutes; b) to this
mixture the Ecogreen -
P, Ecogreen-S, Ecogreen -F, NOVAWET, and EMI-545 were added and mixed for an
16 additional 10 minutes; c) the brine was added with mixing and upon complete
addition the
17 mixing was continued for an additional 30 minutes to form an invert
emulsion; d) the weight
18 material (barite) was added and the fully formulated invert emulsion mud
was stirred for an
19 additional 10 minutes. The resulting invert emulsion drilling mud was found
to have the
2o following properties before and after heat aging at different temperatures:
21
CA 02351088 2001-05-11
wo 0027945 22
PCT/US99126639
Initial Heat Aged at 200° Heat Aged at 250° Heat Aged at
300°
Fforl6h Fforl6h Fforl6h
PV 25 28 28 29
YP 11 17 16 7
Gels IO sec. 9 11 10 5
min. 13 13 12 7
ES 1210 867 851 953
HTHP - 3.2 1.6 2
1
2 Upon review of the above data one of ordinary skill in the art should
appreciate that the
3 above noted invert emulsion drilling fluid formulated in accordance with the
present invention
4 is stable and useful as a drilling fluid even after being heat aged at
temperatures up to 300°C.
5 This is in contrast to the invert emulsion drilling fluid in Example 6 in
which the presence of an
6 alkaline reserve cause the break down and premature aging of the invert
emulsion fluid.
7
8 EXAMPLE 9
9 The following invert emulsion mud that is illustrative of the present
invention was
10 formulated so as to have a density of 14 pounds-per gallon and an oil:water
ratio of 85:15
11
Formulation _l l
methyl oleate 191
VG PLUS 5
VERSALIG 6
EMI-545 12
20% CaClz Brine 51
Barite 340
Acetic Acid 2 rnl
12
13 The rheologicai properties of a first portion of the resulting invert
emulsion were
14 measured both before and after heat aging and gave the following results:
Initial Heat Aged at 200F
for 15 h
PV 26 25
YP 7 1 i
Gels 10 sec. 7 7
10 min. 16 10
ES 952 1054
HTHP - 6
16
17 To a second portion of the above formulated was added NOVATHIN
at a concentration
18 of Ib per barrel. After though mixing, the resulting invert emulsion
5 formed and had the
19 following
rheological
properties
before
and
after
heat
aging:
CA 02351088 2001-05-11
23
WO 00127945 PCT/US99/26639
After Addition Heat Aged at 250 °F
of NOVATHIN for I 5 h
PV 25 24
YP 12 12
Gels 10 sec. 9 7
min. 12 10
ES - 1499
HTHP - 4.8
1
2 Upon review by one of skill in the art, the above results should indicate
that the addition
3 of supplemental surfactants, such as NOVATHIN can be added to the invert
emulsions of the
4 present invention without deleterious effect.
5
6 EXAMPLE 10
7 The following invert emulsion mud that is illustrative of the present
invention was
s formulated so as to have a density of 12 pounds-per gallon and an oil:water
ratio of 80:20
9
Formulation _12
methyl oleate 186
VG PLUS 2
VERSALIG 6
EMI 545 12
20% CaCl2 Brine 68
Barite 231
Acetic Acid 2 ml
I1 The rheological properties of a first portion of the resulting invert
emulsion were
12 measured both before and after heat aging and gave the following results:
13
Initial Heat Aged at 200°F
for 15 h
PV 21 23
YP 5 4
Gels 10 sec. 3 3
10 min. I3 2
ES 1451 704
HTHP - 4.8
14
I5 To a second portion of the above formulated invert emulsion supplemental
surfactant
16 EMI-524 was added in a concentration of about 5 lb per barrel. The
rheological properties of
17 the resulting invert emulsion were measure both before and after heat aging
to give the
18 following results:
19
CA 02351088 2001-05-11
24
WO 00/27945 PCT/US99/2b639
After Addition of Heat Aged at 250 °F
EMI-524 for 15 h
PV 24 24
YP 12 6
Gels 10 sec. 8 4
min. 11 6
ES - 485
HTHP - 2.8
1
2 Upon review by one of skill in the art, the above results should indicate
that the addition
3 of supplemental surfactants, such as EMI-524 may be added to the invert
emulsions of the
4 present invention without deleterious effect.
5
EXAMPLE 11
7 The following invert emulsion mud that is illustrative of the present
invention was
8 formulated so as to have a density of 14 pounds-per gallon and an oil:water
ratio of 85:15
9
Formulation _13
methyl oleate 191
VG PLUS 5
Ecogreen-F 1.5
EMI-545 12
20% CaCl2 Brine 51
Barite 340
Acetic Acid 2 ml
11 The rheological properties of a first portion of the resulting invert
emulsion were
12 measured both before and after heat aging and gave the following results:
13
Initial Heat Aged at 200°F
for 15 h
PV 47 40
YP 27 26
Gels 10 sec. 20 16
10 min. 37 28
ES 968 1202
HTHP - 4
14
To a second portion of the above formulated invert emulsion supplemental
surfactant
16 Ecogreen-S was added in a concentrarion of about 5 lb per barrel. The
rheological properties of
I7 the resulting invert emulsion were measure both before and after heat aging
to give the
18 following results:
19
CA 02351088 2001-05-11
WO 00/27945 25 PCT/US99/26639
After addition of Heat Aged at 250 °F
Ecogreen-S for 15 h
PV 36 32
YP 24 12
Gels 10 sec. 13 8
min. 27 10
ES - 976
HTHP - .80
1
2 Upon review by one of skill in the art, the above results should indicate
that the addition
3 of supplemental surfactants, such as Ecogreen-S may be added to the invert
emulsions of the
4 present invention without deleterious effect.
5
6 EXAMPLE 12
7 The following invert emulsion mud that is illustrative of the present
invention was
8 formulated so as to have a density of 14 pounds-per gallon and an oil:water
ratio of 90:10
9
Formulation _l4
methyl oieate 189
VG PLUS 3
Ecogreen-P 6
Ecogreen-S 2
Ecogreen-F 1
NOVAWET 2
EMI-545 6
20% CaCh Brine 31
Barite 349
Acetic Acid 1 ml
10
11 The rheological properties
of the resulting invert
emulsion were measured
both before
12 and after heat aging and gave the following results:
13
Initial Heat Aged for 16 Heat Aged for 16 Heat Aged for 16
h at 250 °F h at 300 °F h at 350 °F
PV 18 26 28 36
YP 4 7 6 14
Gels 10 sec. 4 5 6 9
10 min. 7 7 9 11
ES 851 1218 1435 1143
14
Upon review of the above Example, one of ordinary skill in the art would
appreciate that
16 the data presented shows that the fluids of this invention, all of which
are absent an alkaline
17 reserve, are stable when subjected to heat aging at temperatures up to
about 300°F. Further such
I8 a person would understand that the fluids made in accordance wit the
present invention remain
19 useful as drilling fluids for periods of time significantly longer than
ester based invert emulsion
drilling fluids which have an alkaline reserve.
CA 02351088 2001-05-11
WO 00127945 26 PCT/US99/26639
I
2 EXAMPLE 13
3 The following invert emulsion muds are illustrative of the present invention
and were
4 formulated so as to have a density of 14 pounds-per gallon and an oil:water
ratio of 90:10:
Formulation _15 _16 _17
methyl ester (7060 Radio)186 186 I 86
lime 0 0 3.5
VG PLUS 2 2 2
Ecogreen-P 6 6 6
Ecogreen-S 2 2 2
Ecogreen-F 2 2 2
Armac HT 0 6 0
20% CaClz Brine 68 68 68
Barite 231 231 231
Acetic Acid 2 2 0
6
7 The rheological properties
of the resulting invert
emulsions were measured
both before
8 and after heat aging and gave the following results:
9
Heat Aged for 1 h at Heat Aged for 16 h
at Heat Aged for 16
h at
150F 250F 350F
Mud 15
PV 30 28 28
YP 17 13 I 1
Gels 10 sec. I 1 7 6
I O min. 13 9 8
ES 568 209 208
API 1 0.6 1
FL
Mud 16
PV 25 25 27
YP 10 16 i6
Gels 10 sec. 10 10 9
10 min. 14 14 11
ES 1097 397 186
API 3.6 2.8 0.4
FL
Mud 17
PV 33 ** **
YP 24 ** **
Gels 10 sec. 13
10 min. 16 ** **
ES 430 ** **
API 2.8
FL
10Note: properties.
**
indicates
mud
was
too
thick
to
measure
I Upon review of the above
1 Example, one of ordinary
skill in the art would
appreciate that
12the fluids may be formulatedaccordance with
data in this
presented
shows
that
drilling
13invention
having
negative
alkalinity.
That
is
to
say
drilling
fluids
can
be
formulated
absent
an
14alkaline reserve, and such
fluids are stable when
subjected to heat aging
at temperatures up
to
15about
300F.
Further
such
a person
would
understand
that
the
fluids
made
in
accordance
with
CA 02351088 2001-05-11
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PCT/US99126639
I the present invention remain useful as drilling fluids for periods of time
significantly longer than
2 ester based invert emulsion drilling fluids which have an alkaline reserve.
3
4 EXAMPLE 14
The following invert emulsion muds that is illustrative of the present
invention were
6 formulated so as to have a density of 14 pounds-per gallon and an oil:water
ratio of 90:10:
Formulation _18 _19
methyl ester (7060 186 186
ltadia)
VG PLUS 2 2
Ecogreen-P 6 6
Ecogreen-S 2 2
Ecogreen-F 2 2
Armac HT 0 2
20% CaClz Brine 68 68
Barite 231 231
Acetic Acid 2 2
8
9 The Theological properties of the resulting invert emulsions were measured
and were
to measured again after addition of acetic acid and further heat aging giving
the following results:
11
Heat Aged for Addition of 2 ml Addition Heat Aged
4 h of 2 rnl for 16 h
at 150 F Acetic Acid & Heat Acetic at 350 F
Acid & Heat
Aged for 16 h at Aged for
16 h at
250 F 325 F
Mud 18
PV 30 27 35 40
YP 19 14 11 5
Gels 10 sec.12 ? 6 3
min.14 11 10 5
ES ?84 241 ?22 421
API - 0.60 2.0 3.2
FL
Mud 19
PV 25 25 28 35
YP ? 8 13 10
Gels 10 sec.9 9 8 5
10 min.13 I2 6 3
ES 1085 440 500 516
API 0 1.4 0.4 6.0
FL
12
13 Upon review of the above Example, one of ordinary skill in the art would
appreciate that
14 the data presented shows that aqueous acidic solutions may be added to the
drilling fluids of the
present invention and that such fluids are stable when subjected to heat aging
at temperatures up
16 to about 350°F. Further such a person would understand that the
fluids made in accordance with
i? the present invention remain useful as drilling fluids despite the
inclusion of acidic components
18 in the drilling fluid.
CA 02351088 2001-05-11
wo oo~i7945
PCTIUS99J26639
1 In view of the preceding, one of ordinary skill in the art should understand
and
2 appreciate that in one illustrative embodiment of the present invention an
invert emulsion
3 drilling fluid includes: an oleaginous phase a non-oleaginous phase an
emulsifying agent
4 capable of stabilizing an invert emulsion drilling fluid under conditions of
negative alkalinity
and wherein the drilling fluid has negative alkalinity. The non-oleaginous
phase may be
d selected from fresh water, sea water, brine, aqueous solutions containing
water soluble organic
7 salts, water soluble alcohols or water soluble glycols or combinations
thereof. The emulsifying
8 agent should be capable of stabilizing the invert emulsion when the non-
oleaginous phase is an
9 aqueous acidic solution and preferably the addition of an aqueous acidic
solution to the invert
to emulsion should not cause the invert emulsion to break. In one preferred
embodiment the non-
11 oleaginous phase has an hydroxide ion concentration of less than 1 x 10'g
moles per liter.
12 Suitable emulsifying agents may be selected from the group consisting of
irnidazoline,
13 amidoamines of fatty acids, tall oil fatty acids, and protanated amines
having the structure
14 [R-Nt-H3] B'
wherein R is a C~2-C~ alkyl group or a CIZ-Czz alkenyl group and B- is a
conjugate base of an
16 acid, and preferably the emulsifying agent comprises from about 0.1 to
about 10.0 percent by
17 weight to volume of said drilling fluid. The oleaginous fluid utilized in
the present illustrative
18 embodiment may be selected from diesel oil, mineral oil, synthetic oil,
ester oils, glycerides of
t9 fatty acids, aliphatic esters, aliphatic ethers, aliphatic acetals, or
other such hydrocarbons and
2o combinations thereof. In one illustrative embodiment a majority of the
oleaginous fluid may
21 include esters of C1-C12 alcohols and C8-C24 monocarboxylic acids and
preferably the esters
22 may be selected from Ci to C12 alkyl alcohol esters of oleic acid, C1 to
C12 alkyl alcohol esters
23 of myristic acid, C1 to C12 alkyl alcohol ester of coco fatty acid, and
mixtures thereof. In the
24 present illustrative embodiment the drilling fluid may further include a
weighting agent such as
barite, calcite, mullite, gallena, manganese oxides, iron oxides, or
combinations thereof.
26 Another illustrative embodiment of the present invention includes a mineral-
oil free
27 invert emulsion drilling fluid including: an oleaginous phase comprising
substantially of esters
28 of C1-C12 alcohols and Cg-C24 monocarboxylic acids; an non-oleaginous
phase; and an
29 emulsifying agent, said emulsifying agent being in sufficient amounts to
stabilize an invert
emulsion and wherein the mineral oil-free invert emulsion drilling fluids has
negative alkalinity.
31 The illustrative drilling fluid should not break upon the addition of an
aqueous acidic solution to
32 the invert emulsion and preferably the non-oleaginous phase may have an
hydroxide ion
33 concentration of less than i x 10'$ moles per liter. That is to say the
emulsifying agent should
CA 02351088 2001-05-11
29
WO 00/27945 PCT/US99/26639
i be capable of stabilizing the invert emulsion in the absence of an alkali
reserve. Preferably the
2 emulsifying agent may be selected from the group consisting o~ imidazoline,
amidoamines of
3 fatty acids, tall oil fatty acids, and protonated amines having the
structure
4 [R N.,.-H3~ B_
wherein R is a C12-C~ alkyl group or a C12-C22 alkenyl group and B- is a
conjugate base
6 of an acid. Preferably the ester is selected from C~ to Clz alkyl alcohol
esters of oleic acid, C1 to
7 C12 alkyl alcohol esters of myristic acid, Ci to C;2 alkyl alcohol ester of
coco fatty acid, and
s mixtures thereof. The illustrative drilling fluid may further include
weighting agents such as
9 barite, mullite, gallena, manganese oxides, iron oxides, or combinations
thereof. The non-
to oleaginous phase may preferably be selected from fresh water, sea water,
brine, aqueous
11 solutions containing water soluble organic salts, water soluble alcohols or
water soluble glycols
12 or combinations thereof.
13 The present invention also includes the use of the drilling fluids
disclosed herein. Thus
14 one of ordinary skill in the art should appreciate that a method of
drilling a subterranean well
with an invert emulsion drilling fluid is within the scope of the present
invention. One such
16 method may include: formulating an invert emulsion drilling fluid such that
the drilling fluid
17 includes, an oleaginous phase; a non-oleaginous phase; an emulsifying
agent, wherein said
18 emulsifying agent is capable of stabilizing the invert emulsion when said
drilling fluid has a
19 negative alkalinity; and drilling said well with said invert emulsion
drilling fluid.
2o While the compositions and methods of this invention have been described in
terms of
21 preferred and illustrative embodiments, it will be apparent to those of
skill in the art that
22 variations may be applied to the process described herein without departing
from the concept
23 and scope of the invention. All such similar substitutes and modifications
apparent to those
24 skilled in the art are deemed to be within the scope and concept of the
invention as it is set out
in the following claims.
