Note: Descriptions are shown in the official language in which they were submitted.
CA 02092114 1999-02-09
D 9222
USE OF SURFACE-ACTIVE ALPHA-SULFO-FATTY ACID
DI-SALTS IN WATER- AND OIL-BASED DRILLING FLUIDS
AND OTHER DRILL-HOLE TREATMENT AGENTS
The invention relates to the use of selected
emulsifiers having an increased ecological compatibility
for the production of fluid dispersed systems which are
present either as W/O invE_rted emulsions comprising a
continuous oil phase or as aqueous emulsions containing
a dispersed oil phase and which are suitable for the
technical application within the field of use of fluid
drill-hole treatment agents.. Referring to a character-
istic example for agents of this kind, the invention is
described hereinbelow by way of oil-based and water-
based drilling fluids, respectively, and drilling muds
formed therewith. However, the field of application of
the modification according to the invention of auxiliary
liquids of the kind involved here is not limited there-
to, while it also includes in particular the areas of
spotting fluids, spacers, auxiliary liquids for workover
and stimulation and for fracturing.
In one particular a;apect of the invention
substantially influences the ecological compatibility
of said auxiliary agents which are being worldwide used
today by employing selected and, more specifically,
- D 9222 _ 2 _ 2 0 9 21 14
ecologically acceptable types of emulsifiers. In its
preferred embodiment the invention intends to use said
biologically acceptable emulsifiers simultaneously in
combination with oil phases having an increased environ-
mental compatibility and especially a biological degrad-
ability.
Discussion of Related Art
In the area of liquid sweeping systems for rock-
drilling to bring-up the removed drill cuttings, the
so-called inverted drilling muds are of excellent
importance which, based on W/O emulsions, contain a
dispersed aqueous phase in the continuous phase. The
content of the dispersed aqueous phase usually is within
the range of from about 5 to 50% by weight.
However, also known are water-based drilling fluids
comprising an emulsified dispersed oil phase (0/W type),
the oil content of which may range from some percent to
about 50% by weight. 0/W emulsion fluids of this kind
exhibit a number of considerable advantages over merely
water-based fluid systems.
The stabilization of each of the selected dispers-
ion forms requires the use of appropriate emulsifiers
either of the W/O type (inverted fluids) or of the O/W
type (emulsion fluids), respectively. Hereto, reference
is made to the pertinent literature, for example, G. R.
Gray, H. C. H. barley, "Composition and Properties of
oil Well Drilling Fluids", 4th Edition, Gulf Publishing
Cp., Houston, London 1981, especially pages 51, 64 and
320 et se
'4
CA 02092114 1999-02-09
D 9222
Today the oil phases of drilling fluids of the type
described here and comparably composed other drill-hole
treatment agents in practice are almost exclusively
formed by mineral oil fractions. This involves a con-
siderable environmental pollution, if, for example, the
drilling muds directly or via the drilled rock will
infiltrate the environment. Mineral oils are only
difficult to decompose and are virtually not anerobic-
ally degradable at all and, thus, to be rated as long-
term pollutants. Nevertheless, even if these oil phases
as the main constituent or at least a substantial
portion of the drilling fluid make a significant start-
ing point for ecological considerations, an equivalent
attention will have to be: paid also to the other com-
ponents of such multi-component systems. Here, the
emulsifiers are of specil:ic importance. Compounds of
this type, in accordance with the intended use thereof,
are highly active substances already at a low concen-
tration which are known to be capable of an intense
interaction with the vegetable or animal organism.
Description of the Inventio~r,
Other than in the operating examples, or where
otherwise indicated, all numbers expressing quantities
of ingredients or reaction conditions used herein are
to be understood as modified in all instances by the
term "about".
The present invention substantially
improves the working agent:3 of the described
type based on continuous or dispersed oil phases in
admixture with aqueous phases, in appreciation of the
ecological compatability thereof, over the working
agents of this kind as common to-day. More specific-
ally, the invention, for the field
of use as involved here, provides 'emulsifiers and/or
emulsifier combinations which have been her se known and
have been described to be environmentally compatible to
a high degree, while they have not been put into use in
the field of use involvE:d here. In the preferred
CA 02092114 1999-02-09
D 9222 -
embodiment of the invention, these environmentally
compatible emulsifiers of the W/O type or of the O/W
type are to be employed in combination with oil/water
phases, where the oil phases themselves have an in-
creased ecological compatibility and, more specifically,
are capable of being decomposed by natural degradation
mechanisms doing little harm to the environment.
The invention provider the use of per se known
surface-active alpha-sulfa-fatty acid di-salts as eco-
logically compatible or acceptable compounds which,
depending on their constitution and kind of interaction
with the surrounding system are to be classified as W/O
emulsifiers or as 0/W emulsifiers. For the sake of
simplicity, said emulsifiers are briefly called
"di-salts" hereinbelow.
Thus, in a first embodiment, the invention relates
to the use of surface-active di-salts of the W/O type
and/or O/W type, as ecologically compatible emulsifiers,
in fluid and pumpable drilling fluids and other fluid
drilling-hole treatment agents which comprise a
continuous or a dispersedr oil phase together with an
aqueous phase and which are suitable for an environ-
mentally acceptable a};ploitation of geological
resources, for example oil or natural gas deposits.
Of particular importance in this context are the
corresponding inverted drilling fluids which in a
continuous oil phase contain a dispersed aqueous phase
CA 02092114 1999-02-09
D 9222 ._
together with emulsifiers and further conventional
auxiliary agents such as thickeners, fluid-loss
additives, weighting agents, soluble salts and/or alkali
reserve. In this embodiment according to the invention
there is provided the use of surface-active di-salts of
the W/O type as emulsifier or at least as a component o-f
an ecologically compatible emulsifier system.'
Preferred is the us,e of emulsifiers based on
surface-active di-salts in combination with environment-
ally compatible ester oils, oleophilic alcohols~and/or
corresponding ethers as continuous or dispersed oil
phase. Here particular reference is to be made to
pertinent developments by applicant describing, in a
greater number older patent: applications, proposals for
substituting the previously common mineral oil fractions
with ecologically compatible readily degradable oil
phases: Thereby, various types of substituting oils
have been presented which may also be used as mixtures.
They include selected oleophilic monocarboxylic acid
esters, selected polycarbo:Kylic acid esters, at least
largely water-insoluble alc:ohols which are fluid under
the operation conditions, corresponding ethers and
selected carbonic acid esters. In summary, reference is
made here to the
copending Canadian Patent Applications Nos. 2,006,010, filed
December 19, 1989, 2,006,009, filed December 12, 1989,
2,047,697, filed March l, 1990, 2,047,706, filed March 29,
1990, 2,009,689; filed February 9, 1990, 2,009,688, filed
February 9, 19990, 2,051,624, filed March 29, 1990, 2,050,935,
filed March 29, 1990, and 2,084,780, filed May 29, 1991. All
of the older applications mentioned here relate to the field
of oil-based drilling fluid system:, especially of the W/O
inverted type. Water-based emulsion fluids using these oil
phases of an increased degradability have been described in
the copending
CA 02092114 1999-02-09
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Canadian Patent Applications Nos. 2,058,636, filed May 7,
1990, 2,057,005, filed May 7, 1990 and 2,057,061, filed May 7,
1990, and 2,084,780 as already mentioned.
The invention, in its most important embodiment,
comprises the use, in combination, of the above-
described emulsifiers of the class of the surface-active
di-salts together with dispersed or continuous oil
phases of the type described last.
Surface-active di-salts and the preparation there-
of have been described in detail' in the prior
art, while emphasis so far has been laid on the use
thereof as O/W emulsifiers - for example in the context
of detergents and cleansers. In this context, reference
is made to the publication by, Stein and Baumann, "alpha-
Sulfonated Fatty Acids and Esters: Manufacturing
Process, Properties and Applications", J. Am. Oil Chem.
Soc. 1975, 52, 323-329, and the primary literature
quoted therein. Already here the good eco-toxilogical
properties of alpha-di-saltyhave been mentioned, while
the high bio-degradability, the low acute oral toxicity
and the good compatibility to the skin have been part-
icularly highlighted. From the more recent literature
dealing with this class of compounds there may be noted
the EP-A2-0 302 402 and 0 302 403 wherein indications
are found on the acute aquatic toxicity of the sodium-
di-salts as determined with orfes and daphniae. In said
latter publications the di-salts are recommended for the
- D 9222 - ~ - 20921 14
use in detergents and cleansers having an improved
eco-compatibility for laundering textile fabrics. From
the extensive printed literature of prior art for
producing such di-salts there may be chosen the U.S.
Patent Specification No. 1,926,442, the paper by A.J.
Stirton "alpha-Sulfo Fatty Acids and Derivatives,
Synthesis, Properties and Use", in J. Am. Oil Chem. Soc.
1962, 39, 490-496 and the literature quoted therein.
Further, especially well known is the sulfonation of fatty
acids with a sub-stoichiometric amount of the sulfon-
ating agent - usually based on S03 - whereupon mixtures
of di-salt and soap are obtained; hereto cf., for
example, the British Patent Specification No. 1,338,935.
Furthermore, it has been known that there are
differences in the solubilities of such di-salts between
the monovalent cations, and especially soaps formed with
alkali metal salts, on the one hand, and the soaps
formed with polyvalent cations, of which here the
alkaline earth metals and/or aluminum, and above all
calcium, are especially considered as the cationic salt-
forming entity. The di-salts of such polyvalent cations
are sparingly soluble if compared to the sodium di-
salts. Upon the addition-_of calcium ions and also of
magnesium ions to an aqueous solution of the sodium
di-salts, the corresponding di-salts of the alkaline
earth metals will be precipitated. This known pre-
cipitation reaction is utilized, for example, in the
field of textile washing and textile agents, where
soluble di-salt compounds are employed as builder
components for sequestering the calcium ions from the
wash liquor: hereto cf., e.g., EP-B1-0 070 190 and
0 070 191.
D 9222 - 8 -
None of said prior art proposals provides an indi-
cation or suggestion of the particular suitability of
alpha-sulfofatty acid di-salts in the soluble embodi-
ments thereof (especially as the alkali di-salts) as
well as just in the comparably insoluble embodiments
thereof (di-salts of polyvalent ions, and especially of
calcium and/or magnesium) as O/W emulsifiers and as W/O
emulsifiers, respectively, in mixed phases containing
water and oil of the type involved here and of the
intended use involved here. This is all the more
surprising in view of the knowledge as per se known of
employing corresponding non-sulfonated fatty acid soaps
- for example the corresponding sodium soaps of the
comparably sparingly soluble calcium soaps of higher
fatty acids - as emulsifiers or emulsifier components
in, for example, drilling fluid systems.
As has been indicated, the invention purposefully
makes use of these per se known soluble or sparingly
soluble salts of alpha-sulfofatty acids (di-salts) and
thereby enables a lasting stabilization of oil-based W/0
inverted emulsions with an absence of the to-day widely
conventional N-containing emulsifier systems, the
compatibility of which is not undisputed, particularly
so in the especially sensitive marine eco-system.
The di-salts as now to be used for the intended use
according to the invention may be characterized by the
following general formula (I)
R-CH(S03M)-C02M (I)
wherein
R in said formula represents linear and/or branched
alkyl which may be saturated and/or olefinically
v
209114
D 9222 - 9 -
unsaturated while, however, it is preferably at least
predominantly saturated, and has at least 4 carbon atoms
in the moiety R. Preferred are corresponding moieties R
having from 6 to 22 carbon atoms.
M represents the same or different cations selected
from the group of alkali metal, alkaline earth metal
(M/2) and/or aluminum (M/3).
Suitable as the feedstock for the production of the
surface-active di-salts are natural and/or synthetic
fatty acids which have a linear structure and/or are
branched. Here the corresponding fatty acids of natural
origin are of particular importance because of the easy
accessability thereof, said acids in general comprising
mixtures of homologous acids within a given range of
carbon atom numbers which is determined by the respect-
ive feedstock. The carboxylic acids or mixtures of
carboxylic acids to be subjected to the a-sulfonation
conveniently are at least largely saturated in nature,
although a use in combination of unsaturated components
will not be excluded. Then in these unsaturated
portions there regularly occurs also a sulfonation at
positions in the chain.
Of particular practical importance are alpha-
sulfonated carboxylic acids of a range comprising at
least 6 carbon atoms (R = 4 in the general formula (I)},
with the range of fatty acids or fatty acid mixtures
comprising from C8 to C24 having particular practical
importance. Di-salts which at least in portions or
preferably predominantly contain fatty acid moieties
comprising 10 and more carbon atoms, and preferably at
least 12 to 14 carbon atoms, are preferred starting
materials for the emulsifier components to be used
2~9~~1~
D 9222 - 10 -
according to the invention. Fatty acid moieties com-
prising 16 to 18 carbon atoms, and more specifically the
corresponding saturated alpha-sulfonated fatty acid
salts, may have particular importance for technical as
well as for economic reasons. Starting materials for
the production of many monocarboxylic acids falling
within these subclasses, and especially of those having
higher numbers of carbon atoms, are vegetable and/or
animal oils and/or fats, respectively, which are known,
in the normal case, to be triglycerides of the acids or
acid mixtures. As the feedstock for the production of
fatty acids of natural origin there may be mentioned
coconut oil, palm kernel oil and/or babassu oil as well
as animal-derived fats and tallows, especially for the
recovery of monocarboxylic acid of the prevailing range
up to C18 and then of essentially saturated components.
Ester oils of vegetable origin based on olefinically
mono- and optionally poly-unsaturated carboxylic acids
of the range of X16-24 are, for example, palm kernel
oil, peanut oil, castor oil, sunflower oil, and
especially rapeseed oil. Fatty acids of this kind, for
a selective alpha-sulfonation, usually require first to
be hydrogenated. But also straight-chain and/or branch-
ed carboxylic acids produced by a synthetic route, which
are producible by oxidation from primarily recovered
synthetic alcohols of the type of oxoalcohols and/or
Ziegler alcohols are suitable components for the pro-
duction of the di-salts and, hence, for the use thereof
within the scope of the inventive action as emulsifier
for, especially, drilling fluids.
Di-salts of the kind concerned by the invention,
when synthesized in a procedure of practice are
obtained, as a rule, in the form of the alkali metal
2092114
- D 9222 - 11 -
salts and, more particularly, in the form of the di-
sodium salts. The di-salts, which are especially
important according to the invention, of polyvalent
cations, and more specifically the corresponding
alkaline earth metal di-salts, may be recovered from the
free acid and/or by way of the ~ se known reaction of
the sodium salts with appropriate alkaline earth metal
salts, especially with soluble alkaline earth metal
salts. It is possible to produce the respective di-
salts in a separate reaction and to employ them as pre-
formed sparingly soluble di-salts, for example in the
drilling mud. However, it has proven to be particularly
advantageous to utilize the possibility of an in situ
formation of such di-salts of polyvalent cations. This
may be illustrated by way of the following example:
The aqueous dispersed phase in oil-based drilling
fluids of the inverted type is generally loaded with
dissolved salts, especially calcium salts such as
calcium chloride, in practical use. If such aqueous
~~ phases containing dissolved alkaline earth metal salts
are used in forming the inverted emulsion, then the
corresponding alkaline earth metal salts of the alpha-
sulfonated fatty acids will be formed even if said
emulsifier components are initially employed in the form
of their sodium salts. Not only does this allow a
particularly economical realization of the teaching
according to the invention, but it has also been shown
that rheologically highly stable inverted emulsions are
accessible by such an in situ formation of the alkaline
earth metal salts which are especially active as W/0
emulsifiers. It will be right apparent in the case of
such a salt-exchange reaction that also the potassium
di-salts may have particularly importance as feedstcok
.::~i
CA 02092114 1999-02-09
D 9222 - 12 -
material: In the reaction with the meaning as described
last, there is formed potassium chloride besides the
calcium di-salts that are active as W/0 emulsifiers,
which potassium chloride transits in the aqueous dis-
persed phase and here is a known preferred constituent
for the inhibition of water-swellable clays within the
exploitation of geological resources.
The di-salt-base emulsifiers, in a preferred
embodiment, are employed as the essential components
forming the type of ernulsion and stabilizing the
emulsion. Nevertheless the teaching according to the
invention also includes mixed systems in which di-salts
are used together with other emulsifier components. It
is preferred that these other emulsifier components on
their own are ecologically compatibly; in this context
reference may be made to Applic,ant's copending Canadian
Patent Application 2,075,208, filed January 21, 1991, wherein
selected ether-based emulsifiers for oil-based inverted
emulsions have been described. ,?mother example for suitable
co-emulsifiers is provided by t:he surface-active alkyl
glycoside co-pounds described in the copending Canadian
Patent Application 2,088,697, filed July 25, 1991.
Salts - and more specifically corresponding salts -
of fatty acids of natural and/or synthetic orgin can be
especially suitable co-e:mulsifiers. In an economic
manner the respective emulsifier mixtures will be
obtained, for example in accordance with the British
Patent Specification No. 1.,338,935 as initially quoted, -
by only a partial reaction of the fatty acid starting
material to form the alpha-sulfonated reaction product.
However, the invention also includes admixing any opt-
ional fatty acids or fatty acid salts as co-emulsifiers
2092114
D 9222 - 13 -
to the respective compositions of active ingredients, in
which case, more specifically, it has been shown that no
problems are caused by a use, in combination, of un-
saturated straight-chain and/or branched fatty acids.
If such emulsifier mixtures are used, then in
preferred embodiments of the invention the di-salts
constitute at least 10% by weight, and preferably at
least 50% by weight, of the respective emulsifier
system.
The di-salts may be used in amounts of from about
0.1 to 10% by weight, relative to the sum of the liquid
phases water and oil. Preferred amounts are within the
range of from about 0.5 to 5% by weight of the emulsi-
fier components, while the range of from about 1 to 3%
by weight of the emulsifier - again relative to the sum
of water + oil - is of particular importance.
The economical production of the emulsifiers
according to the invention is significantly facilitated
by omitting the step of bleaching the reaction products
as primarily obtained, which step in prior art as
evidenced by the pertinent printed publications is
considered as an essential process step. Thus, the
production process for compositions of active substances
containing di-salts within the scope of the invention
may be restricted to the process steps of sulfonation
and salt-formation. The crude reaction product may be
directly put into a commercial use.
In the preferred embodiments as especially featured
in the introduction, the appropriate oil phases are
constituted by the ecologically compatible ester oils,
X092114
D 9222 - 14 -
oleophilic alcohols and/or ethers described in appli-
cant's older applications as quoted. When said agents
are used, the invention relates to the drill-hole
treatment agents which are fluid and pumpable within the
temperature range of from 5 'C to 20 'C, and more
specifically drilling fluids based on
- either a continuous oil phase, especially in
admixture with a dispersed aqueous phase (W/O
inverted type)
- or a dispersed oil phase in a continuous aqueous
phase (0/W emulsion type).
The ecologically compatible oils and oil phases,
with respect to the possible physical properties there-
of, covers a wide range. The invention comprises, on
the one hand, oil phases which are fluid and pu'mpable
also at low temperatures. These, more particularly,
include representatives suitable for the preparation of
W/O emulsions. However, on the other hand, highly
viscous to solid oil phases and materials of this type
may also be included in the use within the scope of the
teaching according to the invention. This may be
exemplified by the following deliberations:
For water-based O/W emulsion fluids a high mobility
of the dispersed oil phase is not required and, as the
case may be, not even desirable. For example, to ensure
good lubricating properties, oil phases adjusted such as
to be comparably viscous may be advantageous. Another
possible use of highly viscous or even solid ecological-
ly compatible oil phases may be constituted, if the
respective oil phase involved in the final product is
only partially formed by said highly viscous to solid
representatives of degradable esters, alcohols and/or
2092114
D 9222 - 15 -
ethers which themselves have been admixed with comparab-
ly highly liquid oils of this kind.
Nevertheless, there is consistently applicable to
all oil phases or mixed oil phases to be used according
to the invention that flash points of at least about
100 °C and preferably flash points of above about 135 °C
are demanded for reasons of safety in operations.
Values that are distinctly higher, particularly those
above 150 °C, may be especially expedient. Furthermore,
there is consistently applicable to the oil phases as
potentially susceptible to hydrolysis that may be used
within the scope of the invention not only that the
requirement of the ecological compatibility will have to
be met by the compound put into use, i.e., for example,
the respectively selected ester oil or ester oil mix-
ture, but also that no toxicological and especially no
inhalation-toxicological danger will be induced upon a
partial saponification in practical use. Within the
scope of the mentioned older applications there has been
described in great detail that here, more particularly,
the various representatives of ester oils are referred
to, with the monofunctional alcohols from the esters
formed being again of particular significance here. In
comparison to polyfunctional alcohols, the lower members
of the monofunctional alcohols are highly volatile, so
that here a partial hydrolysis may cause exposure to
secondary danger. Accordingly, in the classes of the
various ester oils those monofunctional alcohols
included in the use, or the moieties of such alcohols,
have been chosen so that they have at least 6 carbon
atoms, and preferably at least 8 carbon atoms, in the
molecule thereof.
2092114
D 9222 - 16 -
The inverted drilling fluids of the kind involved
according to the invention, irrespectively of a definite
property of the continuous oil phase, in preferred
embodiments have a plastic viscosity (PV) within the
range of from 10 to 60 mPa.s and a flow limit (yield
point, YP) within the range of from 5 to 40 1b/100 ft2 -
each determined at 50 'C.
As an oil phase which is ecologically compatible
and well fluid at low temperature, there have proven to
be useful, more specifically, ester oils of monocarboxyl-
ic acids which then, in a preferred embodiment of the
invention, are derived from at least one of the follow-
ing subclasses:
a) Esters of C1-5-monocarboxylic acids and mono-
and/or polyfunctional alcohols, whereof the
moieties of monohydric alcohols comprise at least 6
carbon atoms and preferably at least 8 carbon atoms
and the polyhydric alcohols preferably have from 2
to 6 carbon atoms in the molecule,
b) Esters of monocarboxylic acids of synthetic and/or
natural origin comprising from 6 to 16 carbon
atoms, and more specifically esters of aliphatic
saturated monocarboxylic acids and mono- and/or
polyfunctional alcohols of the kind mentioned in
a) ,
c) Esters of olefinically mono- and/or polyunsaturated
monocarboxylic acids having at least 16, and
especially 16 to 24 carbon atoms and especially
monofunctional straight-chain and/or branched
alcohols.
H '. : .
CA 02092114 2002-08-02
- 1i -
Starting materials for recovering numerous mono-
carboxylic acids falling under these subclasses,
especially those having a higher number of carbon atoms,
are vegetable and/or animal oils. There may be mention-
ed coconut oil, palm kernel oil and/or babassu oil,
especially as feedstock for the recovery of monocarb-
oxylic acids of the prevailing range up to C18 and of
essentially saturated components. Ester oils of
vegetable origin based on oiez~.nically mono- and optvyon-
ally paly-unsaturated carboxylic acids o:E the range of
C16-24 are, for example, palm kernel oil, peanut oil,
castor oil, sunflower oil, and especially rapeseed oil.
But also components synthetically recovered are import-
ant structural elements for ecologically cor.patible oil
phases on the side of the carboxylic acids as well as on
the side of the alcohols.
Preferabl y, the o~:L r~nase has a Brookf.eld viscosity
of less than about ~0 mP::.. s measureel at a:ez:o to 5° C.
Additives to the oil-based and/or water-based fluid
Inverted drilling muds conventionally contain,
together with the continuous oil phase, the finely
dispersed aqueous phase in amounts of from 5 to 50% by
weight. In water-based emulsicn :fluids tt~.e dispersed
oil phase is usually present in amounts of from at least
about 1 to 2% by weight, frequently in amounts of from
at least about 5% by weight with an upper limit of the
oil portion of about from 40 to ~S~J% by weight - the
percentage by weight in all cases being based on the sum
of the unloaded liquid portions of oil/water.
Besides the water content, there are to be taken
into consideration all of the additives provided for
comparable types of fluids. Said additives may be
water-soluble, oil-soluble and/or water-dispersible
and/or oil-dispersible.
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- D 9222 - 18 -
Conventional additives, besides the emulsifiers
defined according to the invention, include, for
example, fluid-loss additives, soluble and/or insoluble
materials to build-up structural viscosity, alkali
reserve, agents for inhibiting an undesirable water
exchange between drilled formations - e.g. water-swell-
able clays and/or salt layers - and the, e.g., water-
based drilling fluid, wetting agents for an improved
strike of the emulsified oil phase on solid surfaces,
e.g. for improving the lubricating effect, but also for
improving the oleophilic closure of exposed rock
formations, e.g. rock surfaces, biocides, for example
for inhibiting bacterial onset and growth of O/W
emulsions and the like. In detail, reference is here to
be made to pertinent prior art such as described, for
example, in the technical literature as initially
quoted; cf., more specifically, Gray and barley, loc.
cit., Chapter 11, "Drilling Fluid Components". Just by
way of an excerpt, there may be quoted:
Finely dispersed additives for increasing the
density of the fluid: Widely used is barium sulfate
(baryte), but also calcium carbonate (calcite} or the
mixed carbonate of calcium and magnesium (dolomite) are
used.
Agents for a build-up of structural viscosity which
simultaneously will act as fluid-loss additives: Here,
bentonite of hydrophobized bentonite are to be mentioned
in the first place. For salt water fluids, other com-
parable clays, and more specifically attapulgite and
sepiolite are of considerable importance in practice.
~Q~~~~4
D 9222 - 19 -
Also the use in combination of organic polymer
compounds of natural and/or synthetic origin may be of
considerable importance in this connection. There may
be especially mentioned starch or chemically modified
starches, cellulose derivatives such as carboxymethyl-
cellulose, guar gum, xanthan gum, or also merely
synthetic water-soluble and/or water-dispersible polymer
compounds, especially of the type of the high molecular
weight polyacryl amide components with or without an-
ionic or cation modifications, respectively.
Diluents for regulating the viscosity: The so-
called diluents (thinners) may be organic or inorganic
in nature. Examples for organic thinners are tannin
and/or quebracho extract. Further examples are lignite
and lignite derivatives, especially lignosulfonates.
However, as has been set forth hereinabove, in a pre-
ferred embodiment, just here no toxic compounds will be
included in the use, among which in the first place the
respective salts with toxic heavy metals such as
chromium and copper are to be mentioned. Polyphosphate
compounds constitute an example of inorganic thinners.
Additives inhibiting the undesirable water-exchange
with, for example, clays: Here to be considered are the
additives known from prior art for oil- and water-based
drilling fluids. These include halides and/or
carbonates of the alkali and/or alkaline earth metals,
whereof the potassium salts, optionally in combination
with lime, may be of particular importance.
Reference may be made, for example, to the relevant
publications in "Petroleum Engineer International",
209211
D 9222 - 20 -
September 1987, 32-40, and "World Oil", November 1983,
93-97.
Alkali reserves: Here to be taken into consider-
ation are inorganic and/or organic bases adjusted to
match the total behavior of the fluid, and more part-
icularly basic salts or hydroxides of alkali and/or
alkaline earth metals as well as organic bases. Kind
and amount of these basic components will have been
selected and mutually adjusted in a known manner so that
the drilling hole treating agents will be adjusted to a
pH value within the range of from about neutral to
moderately basic, especially to the range of from about
7.5 to 11.
Basically, the amounts of each of the auxiliary
materials and additives is within the conventional range
and, thus, may be learnt from the relevant literature as
quoted.
E X A M P L E S
In the following Examples I and 2, by observation
of a standard formulation for oil-based drilling fluid
systems of the W/O type there are set forth appropriate
drilling fluid systems, wherein each continuous oil
phase is formed by a selected oleophilic carboxylic acid
ester of the following definition:
An ester mixture comprising substantially saturated
fatty acids based on palm kernel and 2-ethylhexanol
which to the by far predominating part is derived from
c12/14 carboxylic acids and conforms to the following
specification:
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D 9222 - 21 -
C8: from 3.5 to 4.5% by weight
C10: from 3.5 to 4.5% by weight
C12: from 65 to 70 % by weight
C14: from 20 to 24 % by weight
C16: about 2 % by weight
C18: from 0.3 to 1 % by weight
The ester mixture is a bright yellow liquid which
has a flash point in excess of 165 °C and a viscosity
(Brookfield, 20 °C) of from 7 to 9 cP.
The viscosity characteristics are determined with
unaged and aged material as follows:
Measurement of the viscosity at 50 °C in a Fann-35-
viscosimeter from the company Baroid Drilling Fluids,
Inc.. In a per se known manner there have been deter-
mined the plastic viscosity (PV), the yield point (YP)
and the gel strength (1b/100 ft2) after 1U seconds and
after 10 minutes. In Example 1 there is further deter-
mined the fluid loss value (HTHP).
Ageing of the respective drilling fluid is effected
by way of a treatment at 125 °C in an autoclave - in a
so-called roller oven - for 16 hours.
The drilling fluid systems are composed in a per se
known manner in accordance with the following basic
formulation:
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CA 02092114 2002-04-29
D 9222 - 22 -
230 ml of carboxylic acid ester oil
26 ml of water
6 g of organophilic bentonite (GELTONET"'"from
the company Baroid Drilling Fluids,
IttC. )
12 g of organophilic lignite (DURATONE'~"'fromthe
company Baroid Drilling Fluids, Inc.)
2 g of lime
6 g of emulsifier based on di-salt
3 g of co-emulsifier based on C18 fatty acid
- only used in Example 2 -
346 g of baryte
9.2 g of CaCl2 . 2 H20
The emulsifier based on di-salt is introduced as a
C16-18-sulfofatty acid di-sodium salt, while in the pre-
processing of the drilling fluid system upon the
addition of calcium chloride it is converted into the
corresponding calcium salt.
The characteristic values determined of the unaged
and of the aged materials have been compiled in the
following Tables relating to the Examples 1 and 2.
~'xa:~ple 1
Unaged Aged
Material Material
Plastic viscosity (PV) 37 34
Yield point (YP) 19 19
Gel strength (1b/100 ft2)
10 seconds 10 12
10 minutes ~ 22 28
HTHP 5 ml
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Example 2
Unaged Aged
Material Material
Plastic viscosity (PV) 39 40
Yield point (YP) 17 13
Gel strength (1b/100 ft2)
seconds 10 7
10 minutes 16 13
