Note: Descriptions are shown in the official language in which they were submitted.
~ 52 7 78
Translation
Rheology-controlled flowable and pumpable aqueous
preparations, for example for use a~ water-based
drilling muds
This invention relates generally to the rheology
control of aqueous liquid phases using viscosity genera-
tors based on fine-particle swellable or even non-swell-
able minerals of natural and/or synthetic origin, the
choice of new controllers providing for reliable rheology
control from ambient temperature to high temperatures,
for example up to 300C or even higher. The teaching
according to the invention is based on an interaction
between the fine-particle minerals on the one hand and
the controllers according to the invention described
hereinafter. The teaching according to the invention
enables the rheological properties and, more particular-
ly, the thixotropic properties of such water-based
preparations to be effectively precision-controlled over
lS a wide temperature range, so that flowable and pumpable
aqueous thixotropic preparations improved in various
respects can be prepared using the auxiliaries described
hereinafter.
The thickening of water-based systems using fine-
particle swellable or even non-swellable clays and/or
other layer compounds of natural and/or synthetic origin
is widely practised. The possibility of thickening, more
particularly thixotropically thickening, aqueous or
water-based liquid phases is utilized in various applica-
tions. Without any claim to completeness, such applica-
tions include the treatment of solid materials, more par-
ticularly metals, the field of fire extinguishing prepar-
ations, the use of thixotropically thickened liquid
phases in water-based paints and coating systems, hy-
draulic fluids and the like.
~ 21~i2778r
Thixotropically thickened water-based auxiliary
liquids are being widely used to an increasing extent in
the technology of geological land-supported drilling and
also for other purposes, for example as soil supports in
excavating operations, more particularly in channel wall
construction, in the sinking of shafts, wells and cais-
sons, in pipe laying and the like. A literature refer-
ence which deals with the corresponding application of
thixotropic liquid systems is, for example, F. Weiss "Die
Standfestigkeit flussigkeitsgestutzter Erdwande" in
Bauingenieur-Praxis, Heft 70 (1967), Verlag W. Ernst &
Sohn, Berlin-Munchen. Water-based drilling fluids which
are sufficiently thickened by the addition of mineral
viscosity generators (normally using suitable polymer
compounds at the same time) without losing any of their
flowability and pumpability under shear stressing and
which - depending on the particular situation - contain
additional dissolved, emulsified and/or suspended auxili-
aries are used on a wide scale. However, many other
liquid auxiliaries in the field of application in ques-
tion - known for example by the technical terms of stim-
ulation, fracturing, spotting, milling or simply cleaning
- are water-based liquid phases which have been thickened
with inorganic and/or organic viscosity generators; see,
for example, MANUAL OF DRILLING FLUIDS TECHNOLOGY, 1985,
NL Baroid/NL Industries, Inc. and A.T. Bourgoyne Jr. et
al. "Applied Drilling Engineering", Society of Petroleum
Engineers, Richardson, Tx, 1986. Relevant information
can also be found in the book by George R. Gray and
O.C.H. Darley entitled "Composition and Properties of Oil
Well Drilling Fluids", 4th Edition 1980/81, Gulf Publish-
ing Company, Houston and the extensive patent and specia-
list literature cited therein.
The present invention is largely described in the
following with reference to such auxiliary liquids for
"- 215277~
use in the field of geological drilling, although it is
by no means limited in its application to this particular
field. The term "earth boring" is also meant to be
broadly interpreted, encompassing both the development
of geological occurrences, such as oil and/or gas, and
technical auxiliary drilling, for example undertunneling,
so-called river crossing, the development of waste dis-
posal sites, water drilling and the like.
The mineral viscosity generators used for the
rheology control of water-based drilling fluids are
typically swellable clays of natural and/or synthetic
origin, although fine-particle non-swelling minerals may
also be used for thixotropic thickening. Corresponding
smectites, such as montmorillonite, bentonite, beidel-
lite, hectorite, saponite and stevensite, are mentionedas examples. Attapulgite is another important auxiliary
of the type in question, see for example US-A 4,664,843,
more particularly columns 5 and 6. Several other propo-
sals are concerned with the synthetic production and use
of fine-particle clay-like minerals, more particularly
corresponding compounds of the hectorite and/or saponite
type, see DE-A 16 67 502 and in particular EP-B 0 260
538. The disclosure of the second of these two docu-
ments, which describes one of applicants' developments,
is hereby included as part of the disclosure of the
present invention.
By selecting suitable natural or synthetic, usually
swellable minerals, in conjunction with water-soluble
and/or swellable polymer compounds, optionally diluents
and the like, it is possible very largely to control the
particular rheological properties required, as reflected
in particular in suitable figures for plastic viscosity
(PV), yield point (YP) and gel strength - determined both
before and after ageing under standard conditions.
Relevant particulars can be found, for example, in the
2152778
above-cited publication "MANUAL OF DRILLING FLUIDS
TECHNOLOGY" of NL Baroid.
An important further development in the rheological
control of mineral-thickened aqueous preparations is the
subject of applicant's earlier German patent application
P 42 24 537.0 which describes the use of mixed hydroxide
compounds of divalent and trivalent metals with a 3-
dimensional space lattice structure of the garnet type
for regulating the thixotropic thickening of aqueous
preparations by means of swellable clays and/or other
swellable layer silicate compounds of natural and/or
synthetic origin. Water-swelling layer silicates known
per se, such as clays of the sodium bentonite type or
even synthetic mineral compounds of the type described in
EP-B 0 260 538, are used in conjunction with the selected
mixed hydroxide compounds of garnet structure mentioned
in the disclosure of that earlier application. The
teaching of the earlier application, of which the dis-
closure is hereby specifically included as part of the
disclosure of the present invention, is based on the
surprising observation that these fine-particle mineral
auxiliaries of garnet structure with a space-filling 3-
dimensional space lattice structure are effective rheol-
ogy control auxiliaries and, so far as the property
spectrum of the thickened aqueous liquid phases is
concerned, can lead to a hitherto unknown combination of
desirable properties.
Further documents relating to the rheology control
of aqueous liquid phases using sodium bentonite, for ex-
ample, as viscosity generator are EP-A 0 207 810 and US-
A 4,664,843. According to these documents, layer sili-
cates known per se, such as clays of the sodium bentonite
or attapulgite type, are used with selected synthetic
mineral mixed oxides which are distinguished by a crys-
talline monolayer structure of the mixed metal hydroxides
~` 2~ 52778
per unit cell. These layer crystals are said to be
"monodispersed" in a liquid carrier so that the individu-
al crystals form separate layers of the mixed metal
hydroxide compounds. Particulars of the quality and mode
of action of these mineral auxiliaries of synthetic
origin known as "mixed metal layered hydroxide compounds
(MMLHC)" can be found in the above-cited patents and in
the article by J.L. Burba III et al. "Laboratory and
Field Evaluation of Novel Inorganic Drilling Fluid
Additives", IADC/SPE 17198, pages 179 to 186.
In the practical application of water-based drilling
fluids, however, selected water-soluble or at least
water-swellable polymer compounds have hitherto played a
predominant part. The drilling fluids used here to
illustrate the problems involved are liquid phases which
are expected to perform a considerable number of dif-
ficult functions at one and the same time. The drilling
fluid cools and lubricates the bit and, at the same time,
is expected to transport the drilled cuttings upwards.
The deeper the borehole, the higher the temperatures to
which the drilling fluid pumped through the borehole is
exposed. Particulars of the various requirements can be
found, for example, in the above-cited US-A 4,664,843.
Another factor to be taken into consideration in this
regard is that sodium bentonite - the most widely used
viscosity generator in water-based drilling fluids - is
sensitive not only to the effect of heat, but also to the
effect of polyvalent cations, more particularly calcium
ions. Hitherto, the result of this in practice has been
that so-called diluents and rheology-controlling polymer
compounds of correspondingly adapted thermal stability
are widely used in working fluids of the type under
discussion here.
The problem addressed by the present invention was
to provide rheology-controlling additives of organic
2 1 ~ ~ 7 7 8
origin which would enable auxiliaries of the type men-
tioned above, more particularly based on thickening
organic polymer compounds, to be partly or completely
replaced. Rheology control would be both possible and
effective at high temperatures. However, by using
certain selected organic auxiliary components, it would
also be possible to retain the possibility of favorably
influencing other important properties of drilling fluids
independent of rheology, for example their lubricity,
their pH control and, in particular, their "inertization"
to polyvalent cations.
The teaching according to the invention is based on
the observation that selected lower alkoxylates of water-
insoluble alcohols which show limited solubility in
water, particularly at room temperature, appear to
interact with the mineral particles very finely dispersed
in the aqueous phase. This interaction enables the
rheological properties of the system to be controllably
influenced. More particularly, this controllable thick-
ening is effective over the entire range of temperaturesencountered in practice without unreasonably impeding the
reduction in viscosity under shear stressing. In addi-
tion, this interaction between very fine-particle miner-
als suspended in the aqueous phase on the one hand and
the viscosity controllers selected in accordance with the
invention on the other hand makes even those mineral
viscosity generators inert to polyvalent metal ions, for
example calcium ions, which would be sensitive to such
components in the absence of the viscosity controllers
according to the invention. Water-swollen sodium ben-
tonite is a typical example of such a viscosity con-
troller.
Subject of the invention
In a first embodiment, therefore, the present
~1~2778
invention relates to the use of lower alkoxylates of
water-insoluble alcohols of natural and/or synthetic
origin (hereinafter also referred to as "controllers")
showing limited solubility in water at room temperature
for effectively thickening and controlling the rheologi-
cal properties of flowable and pumpable aqueous prepara-
tions of fine-particle minerals, even at high tempera-
tures, which may be used in particular as working fluids
in the development of geological formations and/or for
land development, for example for liquid-aided excavating
operations.
In another embodiment, the invention relates to
flowable and pumpable aqueous preparations rheologically
controlled by addition of fine-particle minerals of
natural and/or synthetic origin which are additionally
thickened by addition of organic additives (controllers)
and which may be used in particular as water-based aux-
iliary liquids in the fields of application mentioned
above. In this embodiment, the teaching according to the
invention is characterized in that they contain lower
alkoxylates of water-insoluble alcohols of natural and/or
synthetic origin of the type described hereinafter to
stabilize their rheological properties, even at elevated
temperatures.
In the context of the present invention, lower
alkoxylates of water-insoluble alcohols are understood in
the broadest sense - for both of the embodiments men-
tioned above - to be corresponding lower ethoxylates
and/or lower propoxylates and/or lower butoxylates.
Corresponding lower ethoxylates and/or lower propoxylates
are preferred for the purposes of the invention, lower
ethoxylates being particularly preferred.
Finally, in another embodiment, the invention
relates to the complete or partial replacement of hither-
to typical water-soluble or at least water-swellable
2152778
polymer compounds in water-based flowable preparations
which are thickened with swellable or even non-swellable
mineral fine-particle solids, but which may be used for
example as water-based drilling fluids for other com-
parable applications.
Particulars of the teachinq according to the invention
Water-insoluble alcohols of natural and/or synthetic
origin containing a relatively large number of carbon
atoms are known starting materials for the production of
various classes of surfactant compounds, more particular-
ly anionic and nonionic surfactants. Nonionic surfac-
tants are obtained from these water-insoluble fatty
alcohols in particular by alkoxylation with ethylene
oxide and/or propylene oxide, the necessary equilibrium
between hydrophobic and hydrophilic parts of the molecule
structure being established by the introduction of an
adequate number of EO units, more particularly highly
hydrophilic EO units. Conventional surfactants of this
type are o/w surfactant compounds with sufficiently
highly pronounced hydrophilic molecule components which
ensure that the surfactant components are largely soluble
in aqueous phase at room temperature. Any increase in
the temperature of the aqueous surfactant solution leads
to visible clouding of the aqueous solution, depending on
the cloud point of the particular nonionic surfactant.
This clouding is caused by separation into two liquid
phases of which one is poorer in surfactant and the other
richer in surfactant than the starting solution. The
clouding temperature is dependent on the particular size
of the hydrophobic and hydrophilic groups attached to one
another in the molecule. The temperature at which
separation and hence clouding begins for a given concen-
tration is called the "cloud point". The cloud point is
normally expressed as the cloud point of a 1~ aqueous
.- 21S2778
solution. For a predetermined size of the hydrophobic
part of the mo ecule, the cloud point is a measure of the
degree of alkoxylation and, hence, is an important
performance characteristic. Further particulars can be
found in the relevant specialist literature, see for
example applicants' book entitled "Fettalkohole, Roh-
stoffe, Verfahren und Verwendung", more particularly the
subchapter by H. Lange and M.J. Schwuger entitled "Physi-
kalisch-chemische Eigenschaften von Fettalkoholen und
Folgeprodukten", subchapter 3.5 "Entmischung; Trubungs-
punkt; Verteilungscoeffizient" and J. Glasl "Anwendung
der Fettalkohole und Folgeprodukte", more particularly
subchapter 3.1 "Fettalkohol-Polyglykolether".
The lower alkoxylates of water-insoluble alcohols
used as controllers in accordance with the invention are
distinguished by such a low degree of alkoxylation and
hence by the introduction of hydrophilic groups into the
molecule as a whole that they are regarded as so-called
limited solubility compounds at room temperature, i.e. do
not form clear solutions in water. Fatty alcohol alkoxy-
lates of this type, which are substituted on a statisti-
cal average by 2 to 4 EO groups, for example at a C1218
hydrocarbon radical, are known commercial products for a
variety of different applications. They are marketed by
applicants, for example under the registered names of
"DEHYDOL LS 2", "DEHYDOL LS 3" or "DEHYDOL LS 4", for
various industrial applications, for example for the
leather industry, the textile industry and also in
connection with cold cleaning preparations, car cleaning
preparations and the like.
One of applicants' more recent publications is
concerned with the use inter alia of the class of limited
solubility fatty alcohol ethoxylate compounds under
discussion herein as new N-free thickeners for surfactant
formulations, cf. the article of the same name in "Seif-
- 2152778
en-Ole-Fette-Wachse", No. 2/1990, pages 60 to 68, more
particularly subchapter 3~2 "Fettalkohol-Ethoxylate" and
3.3 "Fettalkohol-Ethoxylate mit eingeengter E0-Homologen-
verteilung" (author A. Behler et al.). This article
describes the effect of lightly ethoxylated fatty alco-
hols on the viscosity of cosmetic formulations (shampoos,
bath and shower preparations). The cosmetic formulations
in question contain anionic surfactants of the alkyl
ether sulfate type as primary surfactant component. The
article in question shows that the aqueous surfactant
preparation can be thickened by the use of selected
nonionic fatty alcohol ethoxylates with a limited degree
of ethoxylation. The objective of mixtures such as these
is to influence the surfactant micelle structure. More
particularly, isometric spherical micelles are said to be
converted into anisometric rodlet or disk micelles.
Macroscopically, this is reflected in an increase in the
viscosity of the surfactant solution. This mechanism
clearly has no connection with the interaction underlying
the teaching according to the invention between suspended
and, preferably, water-swollen mineral particles and the
controllers selected in accordance with the invention
based on lower alkoxylates of water-insoluble alcohols
showing limited solubility in water at room temperature.
25An article published at the end of the forties
relates to the use of typical o/w detergents as auxili-
aries for suspending clays in high concentrations in
water-based drilling muds (T.M. Doscher, "CHARACTERISTICS
OF DETERGENT-SUSPENDED CLAYS", Journ. of Phys. and
30Colloid Chem. 53 (1949), 1362). The article in question
is concerned solely with highly concentrated suspensions
of clays in an aqueous phase which are distinguished by
the following test parameters: the swellable parts of
natural clay are flocculated out by reaction with large
quantities of calcium chloride, so that suspensions of
- 21~2778
non-swelling solids are said to be produced. The clay
solids content of these suspensions is very high, more
particularly in the range from about 20 to 60% by weight,
based on the aqueous suspension. Drilling fluids of this
type cannot be compared with the low-solids water-based
drilling fluids with which the present invention is
concerned. Modern systems of this type use the struc-
ture- and rheology-determining, more particularly swell-
able clays in far smaller amounts - typically well below
10 to 15% by weight and, preferably, at most about 5% by
weight, based on the system as a whole. Understandably,
controlling the rheological properties of such low-solids
liquid phases and eliminating any problems arising in
this regard cannot be compared in any way with the
technical problems of water-based systems containing non-
swelling clay compounds in very much higher concentra-
tions. In low-clay systems, the swellability of the clay
is crucial to the development of the required rheology.
In their case, the difficulties to be overcome lie on the
one hand in the establishment of adequate temperature
stability of the system, so that the desired rheological
properties can be adjusted and maintained, even at
temperatures above about 100C, for example up to around
250C. On the other hand, swellable clays have to be
protected against the effect of polyvalent cations,
particularly calcium.
It has surprisingly been found that the use of small
quantities of the lower alkoxylates of water-insoluble
alcohols of natural and/or synthetic origin showing
limited solubility in water at room temperature, which
are referred to in accordance with the invention as
"controllers", is capable of optimally solving the
problems discussed in the foregoing. In addition, the
aqueous flowable and pumpable preparations thickened in
accordance with the invention, more particularly aqueous
- 2152778
preparations of swellable fine-particle minerals of the
~odium bentonite and/or ~ynthetic swellable layer sili-
cate type, can be further-controlled and optimized.
One preferred embodiment of the invention is charac-
terized by the use of limited solubility controllers ofthe type mentioned above which are present in liquid form
at temperatures of up to about 100C and which in par-
ticular have pour points and flow points below about
80C. Particularly important auxiliaries of the type
defined in accordance with the invention have pour points
and flow points below 50C, preferably below 25C and
more preferably below 10C. The most important auxili-
aries of the type defined in accordance with the inven-
tion are distinguished by pour points and flow points
below 0C. Accordingly, in the temperature ranges which
normally prevail in practice, they are present as liquids
which may readily be processed in situ or added, for
example, to the water-based drilling fluid in operation,
even under offshore conditions.
The controllers used in accordance with the inven-
tion, which are liquid at room temperature, may be
further defined by their preferred cloud points, as
measured on a 1% by weight mixture in water. Their cloud
points are preferably below 25C, best below 20C and
generally below 10C. Limited solubility controllers of
the type mentioned with cloud points below 0C can be
particularly interesting representatives for the teaching
according to the invention.
Important representatives of controllers according
to the invention are lower alkoxylates of aliphatic
and/or ethylenically unsaturated alcohols containing at
least 6 carbon atoms and preferably at least 8 to 10
carbon atoms. Particularly suitable thickeners are
derived from monohydric C1024 and preferably Cl218 alcohols
of natural and/or synthetic origin. The alcohol mole-
21~2778
cules may be linear, branched and/or cyclic. They may bealiphatically saturated or monoolefinically or even poly-
olefinically unsaturated. Aromatic systems are less
suitable for ecological reasons alone and, accordingly,
are not preferred.
The limited solubility controllers defined in
accordance with the invention are obtained from these
water-insoluble alcoholic components by ethoxylation and/
or propoxylation and/or butoxylation. For example, fatty
alcohols can be reacted with ethylene oxide (EO) and/or
propylene oxide (P0) and/or butylene oxide (B0) in the
presence of catalysts to form polyglycol ethers. The
hydrophilicity or water solubility of the fatty alcohol
derivatives increases while their oil solubility decreas-
es with increasing degree of addition. Accordingly, thehydrophilic E0 chain and/or P0 chain and/or B0 chain has
to be correctly adapted to the oleophilic nature of the
alcohol radical for the limited solubility thickeners of
the type in question used in accordance with the inven-
tion. For example, depending on the chain length of thestarting alcohol, surfactants which form clear solutions
in water at 20~C are obtained with 3 moles of E0 (in the
case of n-octanol) to 7 moles of E0 (in the case of
tallow alcohol). In the two cases mentioned, the limited
solubility condition is exceeded in the direction of
water-soluble nonionic surfactant compounds. According-
ly, controllers according to the invention should have
relatively short oligo-E0 chains.
A particularly important class of controllers in the
context of the teaching according to the invention are
the lower alkoxylates, more particularly the lower
ethoxylates, of fatty alcohols containing 12 to 18 carbon
atoms. In their case, both technical mixtures in the
Cl2_l8 range and much narrower-range starting materials,
for example fatty alcohols in the Cl2/l4 or Cl2/l6 range~ may
- 2152778
14
be used as the fatty alcohol starting material for pro-
ducing the thickeners. Limited solubility ethoxylates
of these starting materials and hence optimized con-
trollers in the context of the invention are obtained by
the addition of 1 to 3 EO groups and, more particularly,
2 to 3 EO groups (on a statistical average) onto fatty
alcohols of the type just mentioned. PO or BO groups
introduced are known to be less hydrophilic than corre-
sponding EO groups, so that the number of PO chain links
or BO chain links can be slightly shifted upwards. The
use of PO groups and, in particular, the combination of
EO/PO groups can be useful for other reasons, for example
for suppressing any tendency towards foaming. The same
applies to the use of BO groups. The general knowledge
of the expert on corresponding surface-active compounds
may again be applied in this regard. The relevant
literature is represented, for example, by applicants'
above-mentioned book entitled "Fettalkohole, Rohstoffe,
Verfahren und Verwendung", cf. in particular the subchap-
ter by J. Glasl "Anwendung der Fettalkohole und Folge-
produkte", loc. cit., pages 132 to 143 and in particular
the Tables on pages 133 to 138 with their data on ethoxy-
lates based on C12l4 coconut oil fatty alcohol, on C1216
coconut oil fatty alcohol, on C1218 coconut oil fatty
alcohol and on oleyl and cetyl alcohol.
The controllers according to the invention are used
in aqueous suspensions of fine-particle minerals which,
in one preferred embodiment, are swellable in water
although they may even be non-swellable. The minerals
may be of natural and/or synthetic origin. The general
knowledge of the relevant expert, as derived for example
from the literature cited at the beginning, is the
determining factor for the most important application of
the rheology-controlled aqueous preparations according to
the invention, i.e. flowable and pumpable auxiliaries for
~ 2152778
use in soil excavating operations and/or as geological
borehole servicing fluids. According to the invention,
natural and/or synthetic clays, such as bentonite,
attapulgite, hectorite and/or saponite or even mixtures
thereof with mineral controllers, such as katoite or the
mixed metal layered hydroxide compounds (MMLHC) mentioned
above, are preferably used as mineral component(s),
sodium bentonite being particularly preferred.
In addition to the literature references cited above
in connection with expert knowledge of mineral solids to
be thickened, more particularly of the sodium bentonite
type, reference is made here to applicants' earlier
German patent application P 42 24 537.0, of which the
disclosure is hereby specifically included as part of the
disclosure of the present invention.
The viscosity generators based on mineral fine-
particle solids, preferably-swellable or even non-swell-
able clays, are typically used in quantities of at most
about 15% by weight and, in particular, in quantities
below about 10% by weight. Suitable quantities are, for
example, in the range from about 1.5 to 9% by weight and
preferably in the range from about 2 to 8% by weight.
For the water-based drilling fluids based on sodium
bentonite typically used in practice, the bentonite is
normally used in quantities of, for example, about 2 to
6% by weight, based on the aqueous phase.
Highly effective mineral thickeners of synthetic
origin, which may even be used in much smaller quan-
tities, are described for example in the above-cited EP-
30B 0 260 538 which has been included in the disclosure of
the present invention.
In another preferred embodiment of the invention,
the quantity in which the particular limited solubility
controller as defined in the description of the invention
is used is adapted to the particular quantity of mineral
` 2152778
16
fine-particle thickening components used. According to
the invention, the organic controller component(s) is/are
used in at most substantially equivalent quantities to
the fine-particle clays. The organic controllers are
preferably used in smaller quantities than the clays,
mixing ratios (by weight) of controller to clay of 0.01:1
to 0.8:1 and preferably of the order of 0.05:1 to 0.5:1
being particularly preferred.
Accordingly, taking into account the limited quanti-
ties in which mineral thickening components are presently
used in water-based systems of the type in question, the
organic controllers according to the invention are often
used in quantities of up to about 5% by weight, based on
the water-based system, and preferably in quantities of
up to about 3% by weight. It has actually been found
that even very small quantities of the controller com-
ponents according to the invention are sufficient to
initiate permanent rheology-stabilizing effects. Thus,
upper limits of about 1.5 to 2% by weight (again based on
the flowable and pumpable aqueous preparation) are often
sufficient in practice for the quantity of organic con-
troller to be used. The following Examples illustrating
the teaching according to the invention show the extreme
effectiveness of even very small additions of the con-
troller components, for example of the order of 0.2 to 1%by weight and preferably of the order of 0.5 to 1% by
weight of the aqueous preparation. Despite these small
amounts of controller components, for example of the
order of 0.3 to 0.8% by weight, the clay phase, more
particularly the water-swollen clay phase, is permanently
stabilized, so that predetermined rheological values in
regard to plastic viscosity, yield point and gel strength
are maintained over wide temperature ranges in which the
particular systems tested would show significant changes
in their rheological properties without the addition of
- 2152778
17
the controllers according to the invention. Such changes
include on the one hand the known tendency of sodium
bentonite to gel at relatively high temperatures and the
collapse of rheology at relatively high temperatures. By
using the controller components according to the inven-
tion, the particular system is stabilized in both direc-
tions.
In this connection, it may be useful in some cases
to allow even the systems stabilized in accordance with
the invention a limited time for stabilization of the
rheological properties. The freshly prepared water-based
mixture may lead to a - normally limited - change in the
rheological properties on initial exposure to relatively
high temperatures. However, once this incipient ageing
process has been controlled in accordance with the
invention, the now existing level of rheological proper-
ties is maintained over prolonged periods and/or wide
temperature ranges.
Another advantage is again emphasized at this
juncture. The thickened aqueous systems are stabilized
not only against variations in the temperatures to which
they are exposed. More particularly, the susceptibility
of water-swelling clays of the sodium bentonite type to
the effect of polyvalent cations is also eliminated or at
least limited to a very considerable extent. Calcium is
known to be an element of particular significance in this
regard in the field of drilling muds insofar as it is
regularly introduced into the drilling mud system in the
form of its water-soluble salts during the penetration of
corresponding water-containing layers.
The use in accordance with the invention of the
controllers or stabilizers based on limited solubility
lower alkoxylates of water-insoluble alcohols, preferably
based on limited solubility fatty alcohol ethoxylates,
leads to another important possibility: the polymer
~-`; 2152778
18
compounds hitherto almost always required in mixtures of
the type in question here are now completely or at least
partly unnecessary. The importance of using polymer
compounds of natural and/or synthetic origin is discussed
in the literature cited at the beginning. In general,
the polymer compounds are said to arrest weaknesses in
the mineral-thickened system occurring in practice as a
result of variations in the working conditions. Stabili-
zation of the mineral thickener system by using con-
trollers of the described type in accordance with theinvention is so thorough that it may be regarded as an at
least equivalent replacement of the polymer compounds.
Of crucial significance in this regard is the well-known
high thermal stability of nonionic fatty alcohol alkoxy-
lates which enable the stabilizing principle according tothe invention to be applied over the wide temperature
range occurring in practice, for example up to 300~C or
even higher. The use of limited quantities of selected
polymer compounds does of course fall within the scope of
the teaching according to the invention.
Knowledge of the production of nonionic surfactants
may be used in connection with the production and charac-
teristics of the controllers according to the invention.
It may be briefly summarized as follows: suitable alkoxy-
lates are those which have been conventionally equippedwith a comparatively broad statistical distribution of
the chain lengths of the E0, P0 and/or B0 groups. How-
ever, alkoxylates of the so-called "NRE (narrow-range
ethoxylate)" type produced by more modern methods are
also suitable. The following observations should be
interpreted in this sense: preferred alcohol alkoxylates
are provided with up to 7 alkoxy groups and preferably
with up to 4 alkoxy groups (statistical mean values)
while particularly preferred controllers or thickeners
are Cl2-18 fatty alcohol-E0x compounds where x is a number
2152778
of 1 to 3.
In one important e~bodiment, the teaching according
to the invention is of particular significance in connec-
tion with the production of water-based borehole servic-
ing fluids, more particularly drilling muds, which to-
gether with the thickened aqueous phase contain a dis-
persed organic oil phase - flowable in particular at
working temperatures - in finely emulsified form.
Drilling muds of this type are known to be o/w emulsions
which, so far as their performance properties are con-
cerned, occupy the middle ground between purely aqueous
systems and oil-based invert muds. Detailed information
can be found, for example, in the above-cited book by
George R. Gray and O.C.H. Darley entitled "Composition
and Properties of Oil Well Drilling Fluids", 4th Edition,
1980/81, Gulf Publishing Company, Houston and the exten-
sive specialist and patent literature cited therein. O/w
drilling muds of this type are typically 3-phase systems
of oil, water and fine-particle solids.
O/w emulsions such as these are of particular
significance in the context of the invention. Preferred
embodiments are characterized by the use of ecologically
safe dispersed oil phases which are based in particular
on at least substantially water-insoluble alcohols,
correspondingly water-insoluble ethers and esters of
mono- and/or polycarboxylic acids and comparable carbonic
acid esters. Further information on this subject can be
found in relevant publications and patent applications
in applicants' name (DE-A 39 15 875, DE-A 39 15 876, DE-
A 39 16 550, DE-A 40 18 228 and DE-A 40 19 266). The
subject matter of these documents is hereby specifically
included as part of the disclosure of the present inven-
tion in connection with the particular embodiment in
question.
In connection with water-based borehole servicing
21~2778
fluids, more particularly drilling muds, the addition of
auxiliaries to inhibit drilled rock showing high sensi-
tivity to water can be of particular significance. For
example, the water-soluble salts known from the prior art
as additives for water-based drilling fluids may be used
for this purpose. The water-soluble salts in question
are in particular halides of the alkali and/or alkaline
earth metals, among which corresponding potassium salts,
particularly in combination with lime, can be of particu-
lar significance. Recent developments in this field arebased inter alia on the use of water-soluble polyalco-
hols, such as polyglycols, the use of glycerol, cross-
linked and/or uncrosslinked oligoglycerols and/or poly-
glycerols and comparable compounds, see for example EP-A
0 293 191 (glycerol and/or polyglycerols), US-A 4,830,765
(polyhydric alcohols, glycol, glycol ethers, polypropy-
lene glycols, polyethylene glycols, ethylene oxide/propy-
lene oxide copolymers, alcohol-initiated EO-PO copolymers
and mixtures thereof), M.E. Chenevert "Glycerol Additive
Provides Shale Stability" in Oil & Gas Journal, July,
1989, 60-64 and D. Green et al. "Glycerol-Based Mud
System Resolves Hole Sloughing Problems" in WORLD OIL,
September 1989, 50/51. The regulation and adjustment of
viscosity by the measures proposed in accordance with the
invention is also of importance in connection with water-
based borehole servicing fluids modified in this way.
In the particular embodiment of the invention in
question here, the viscosity-controlled water-based
drilling auxiliaries may contain any of the additives
typically used for comparable drilling fluids. These
additives may be water-soluble, oil-soluble and/or water-
or oil-dispersible. Known additives for water-based
drilling fluids, more particularly o/w drilling emul-
sions, are for example emulsifiers, fluid loss additives,
alkali reserves, weighting agents, agents for inhibiting
21~2778
the unwanted exchange of water between drilled formations
and the water-based drilling fluid, wetting agents to
improve the adsorption of the emulsified oil phase onto
solid surfaces, disinfectants and the like. Further
information on this subject can be found in the relevant
prior art as represented, for example, by the above-cited
book by Gray/Darley. Further detailed information on
o/w-based drilling emulsions can also be found in appli-
cants' above-cited patent applications.
For safely controlling and developing the interac-
tion between the fine-particle layer silicate compounds
on the one hand and the controllers based on lower,
limited solubility alkoxide compounds of water-insoluble
alcohols on the other hand, it may be advisable in the
preparation of drilling systems from a number of com-
ponents to ensure that the interaction between these two
principal components is not affected by other possible
constituents. Accordingly, it may be desirable for
example to combine an aqueous sodium bentonite suspension
adjusted with NaOH to typical pH values in the range from
about 7.5 to 12 and more particularly in the range from
about 8 to 10.5-11 with controllers according to the
invention in the absence of substantial quantities of
polyvalent cations, particularly calcium ions, and to
initiate the suspension/controller interaction. Inten-
slve mixing of the components, if desired under the
effect of raised temperatures, may be useful for this
purpose. The developing structures are thus optimally
suitable for further mixing with any required and/or
desired additional constituents of the ready-to-use
water-based auxiliary and working fluids.
In one embodiment of the invention, the controllers
are used together with defoamers or foam inhibitors.
This embodiment can be of particular significance in
cases where the water-based aqueous preparations are
2152778
22
exposed to intensive mechanical forces under conditions
which can lead to foaming. Although basically any
defoamers or foam inhibitors known to the expert may be
used, one particular component has proved to be particu-
larly useful in the context of the teaching according tothe invention. The component in question is a Guerbet
alcohol, i.e. a fatty alcohol condensation product
branched in the 2-position to the hydroxyl group.
Particulars of this class of alcohols can be found, for
example, in applicants' book entitled "Fettalkohole,
Rohstoffe, Verfahren und Verwendung", pages 168/169. The
foam inhibitors are used together with the controllers
according to the invention generally in small quantities,
based on the particular quantity of controller used.
Thus, the foam inhibitor may be used in quantities of
from about 1 to 50% by weight and preferably in quanti-
ties of from about 5 to 30% by weight, based on the
quantity of controller according to the invention.
E x a m p 1 e s
In the following Examples, the rheological behavior
of aqueous alkaline sodium bentonite suspensions is
tested and numerically determined, the particular test
suspensions being defined in the individual Examples.
Unless otherwise specifically stated, the following
procedure is adopted for testing the products produced:
Using commercial fine-particle sodium bentonite, an
aqueous suspension containing the particular quantity of
bentonite indicated is prepared by intensively stirring
the powder-form mineral into the water (tapwater) phase.
A pH value of 11 is adjusted with 30% sodium hydroxide.
The bentonite suspension thus prepared is left standing
overnight at room temperature.
The following values which have been introduced into
the technology of auxiliary fluids for geological dril-
~152778
23
ling (particularly for identifying the rheologicalproperties of drilling muds) are determined as the
rheological characteristics:
Plastic viscosity (PV) in cP
Yield point (YP) in lb/100 ft2
Gel strength - 10 secs. and 10 mins. - in lb/100 ft2
Unless otherwise stated, the particular suspensions
are tested before and after ageing. Ageing is carried
out in a so-called roller oven over a period of 16 hours
at 250F (121C), again unless otherwise specifically
stated.
The following Examples describe the combination of
materials on which the particular measurements were
based. The test results obtained are then set out in
tabular form.
Example 1
A 3.5% by weight sodium bentonite suspension (12
lbs/bbl, pH 11) is initially prepared as the blank value
in the manner described above. Its rheological data are
determined before and after ageing.
In a second stage, the Cl2/14 ethoxylate marketed by
2S applicants under the trade name of "Dehydol LS2" (normal
statistical E0 distribution; mean E0 value = 2) is added
to and intensively incorporated in the bentonite suspen-
sion as a controller according to the invention. The
controller is used in a quantity of 0.5% by weight (1.5
lb/bbl). The rheological data of this suspension are
determined before and after ageing. The test results
obtained with the blank sample and with the material
formulated in accordance with the invention are set out
in Table 1 below.
2152778
24
Table 1
PV YP Gel strength
10 secs. 10 mins.
Blank value (BV)
5 Before ageing 5 3 2 6
BV after ageing 5 4 1 7
+ 0.5% by weight LS2
Before ageing 12 42 25 23
After ageing 12 84 37 33
Example 2
An aqueous suspension is initially prepared as
described above using 2.9% by weight of sodium bentonite
(pH 11). In comparative tests, samples of this suspen-
sion are added in a quantity of 1.5% by weight to and
intensively incorporated in a commercial polymer compound
from the field of drilling fluids based on carboxymethyl
cellulose (commercial product "CMC U 300 S9"). The
rheological data of the drilling fluid are determined
before and after ageing.
For comparison, the controller of Example 1 ("Dehy-
dol LS2") is added in a quantity of 0.5% by weight to and
incorporated as described in the same sodium bentonite
suspension instead of the polymer compound. In this
case, too, the rheological data of the material are
determined before and after ageing. The results obtained
are set out in Table 2.
- 21527~
Table 2
PV YP Gel strength
10 secs. 10 mins.
+ 1.5% by weight CMC
Before ageing 25 17 3 20
After ageing 16 11 2 7
+ 0.5% by weight LS2
Before ageing 8 32 16 10
After ageing 7 39 17 12
The temperature-stable control of the rheological
values by the auxiliary according to the invention by
comparison with the known polymer compounds used in a far
larger quantity is clearly apparent.
Example 3
In a series of comparative tests, the two test
suspensions of Example 2 are tested for their stability
to the addition of increasing quantities of calcium
chloride. In a first step, quantities of 0.125% by
weight, 0.25% by weight and finally 0.5% by weight CaCl2
are added to three separate batches of the CMC-containing
bentonite suspension which of course had been originally
prepared using tapwater. All the suspensions are aged.
The plastic viscosity (PV) and yield point (YP) of the
aged suspensions are determined. The results are set out
in Table 3a below.
In a series of comparative tests, calcium chloride
is again added to separate samples of a bentonite suspen-
sion prepared in accordance with the invention and
controlled with "Dehydol LS2", followed by ageing. The
following quantities of calcium chloride are used: 0.25%
by weight, 0.5% by weight and 1.0% by weight. The
rheological data (PV and YP) of the suspensions before
- ` ~152778
26
and after ageing are set out in Table 3b below.
Table 3a
PV YP
S No addition of CaCl2 16 11
+ 0.125% by weight of CaCl2 16 9
+ 0.25 % by weight of CaCl2 14 8
+ 0.5 % by weight of CaCl2 12 9
Table 3b
PV YP
No addition of CaCl2 7 39
+ 0.25% by weight of CaCl2 4 44
+ 0.5 % by weight of CaCl2 3 42
+ 1.0 % by weight of CaCl2 4 34
The stability of the yield point (YP) to the addi-
tion of considerable quantities of divalent calcium is
clearly apparent.
Example 4
The effect of the degree of ethoxylation of the
controllers used in accordance with the invention is
determined in a series of comparative tests. All the
25measurements are carried out with a 2.9% by weight
suspension of sodium bentonite (pH 11) prepared as
described with tapwater, to which the alcohol ethoxylates
are added on the one hand in a quantity of 0.5% by weight
and on the other hand in a quantity of 2.0% by weight.
30All the results set out in Table 4 below relate to
aged test specimens (ageing carried out as described
above in the roller oven for 16 hours at 250~F (121C)).
In addition to the data of Table 4, the following
observation is crucial: the drilling fluids prepared with
35 the limited solubility regulators according to the
~ 2152778
invention of the "LS2" and "LS3" type show no tendency to
separate, even after ageing. The drilling fluids pre-
pared with the nonionic surfactant "Dehydol LS7" show a
pronounced tendency to separate after ageing. In addi-
5 tion to the thickened aqueous bentonite phase, free wateris formed as a separate phase. The same tendency also
exists, but is not as pronounced, even where "Dehydol
LS4 " is used.
The collapse of the yield point under the relatively
high dosage of the "LS7" component is also interesting.
Table 4
PV YP Gel strength
10 secs. 10 mins.
+0.5% by weightLS2 10 2817 22
+2.0% by weightLS2 7 1912 8
+0.5% by weightLS3 7 3016 14
+2.0% by weightLS3 15 2218 12
+0.5% by weightLS4 5 3617 12
+0.5% by weightLS7 9 3415 12
+2.0% by weightLS7 8 4 18 20
Example 5
The tests of this Example investigate the influence
and effect of using limited quantities of the mineral
30 controller described in earlier German patent application
P 42 24 537.0 based on mixed hydroxide compounds of
divalent and trivalent metals with a 3-dimensional space
lattice structure of the garnet type - in addition to the
controllers according to the invention based on fatty
3 5 alkoxylates.
2152778
A dry powder is used as the inorganic controller
mixture in accordance with the earlier German patent
application cited above. It consists of the following
mixture:
90% by weight of a very lightly silicate-modified katoite
- sio4 content, based on the silicate-free katoite unit
Ca3Al2(0H)12, less than 0.1 sio4 units.
10% by weight of a highly swellable synthetic hectorite
according to EP-B 0 260 538.
Two variants are investigated in connection with the
production of the controller-stabilized bentonite suspen-
sion:
Variant A: The controller according to the inventionbased on the fatty alcohol ethoxylate is first added to
and intensively mixed with the bentonite suspension (12
lb/bbl sodium bentonite, pH 11). The commercial product
"Dehydol LS3" (Henkel KGaA) is used as the controller.
The mineral controller mixture according to the
earlier application is then thoroughly mixed with the
suspension now present. The rheology data are then
determined before and after ageing.
Variant B: The procedure is as described for variant A
except that, on this occasion, the mineral controller
according to the earlier application is first incor-
porated in the aqueous bentonite suspension and only
after it has been intensively mixed is the controller
according to the invention based on fatty alcohol ethoxy-
late (LS3) incorporated. In this case, too, the rheolog-
ical data are determined before and after ageing.
In both cases, 0.5 lb/bbl of the mineral controller
- 2I52778
29
mixture and 0.9 lb/bbl of the controller based on fatty
alcohol thoxylate were added to the basic bentonite
suspension (12 lb/bbl, pH 11).
In another version of variant B, applicants' commer-
cial product "LS2" is used as the controller based onfatty alcohol ethoxylate.
The rheological data determined are set out in Table
5 below.
Table 5
PV YP Gel strength
10 secs. 10 mins.
Variant A
Before ageing 13 96 23 26
After ageing 9 37 19 19
Variant B
Before ageing 20 177 55 51
After ageing 11 78 25 37
Variant B + LS2
After ageing 11 63 32 44
It can clearly be seen that the order of variant B
leads to a distinctly greater increase in the rheological
data than variant A.
Example 6
A bentonite suspension is prepared in the same way
as in Example 5, variant B, but with an increased quan-
tity of controller based on fatty alcohol ethoxylate.
The final suspension contains the following constituents:
12 lb/bbl bentonite, pH 11; 0.5 lb/bbl of the mineral
controller mixture and 1.3 lb/bbl of the controller
21S2~78
according to the invention ("Dehydol LS2").
The rheological data are measured both before and
after ageing at 250F (121C) and for 16 hours at 350F
(177C). The results obtained are set out in Table 6
below.
Table 6
PV YP Gel strength
10 secs. 10 mins.
Before ageing 19 161 73 60
After ageing (250F) 11 54 19 23
After ageing (350F) 14 45 30 28
Example 7
On the one hand, 0.5~ by weight of "Dehydol LS2" is
added to a 3.5% by weight bentonite suspension (pH 11);
on the other hand, a corresponding narrow-range material
is used instead of this thickener. The commercial
product "Arlypon F" is used as controller.
The rheological data measured on the unaged samples
are set out in Table 7 below, suspension A. The figures
shown in brackets in the yield point column are deter-
25mined after ageing at 250F (121C).
In a second series of tests, the mineral controller
mixture according to Example 5 (0.2% by weight) is first
added to the aqueous bentonite suspension. The rheologi-
cal data measured on the unaged samples are set out in
Table 7 as "suspension B".
- . 2152778
Table 7
PV YP Gel strength
10 secs. 10 mins.
Suspension A
+ LS2 12 42(81) 25 23
+ Arlypon F 10 43(82) 18 19
Suspension B
+ LS2 10 161 73 60
+ Arlypon F 20 125 42 38
Example 8
Bentonite suspensions containing Dehydol LS 2
according to Example 1 as controller were tested for foam
inhibition. Various organic compounds were used as the
foam inhibitors. 3.5% by weight sodium bentonite suspen-
sions adjusted to pH 11 were again used for the tests.
The following mixtures were tested:
8.1) 80% by weight of Dehydol LS 2
20~ by weight of C16 Guerbet alcohol (2-hexyldecan-
l-ol)
8.2) 90% by weight of Dehydol LS 2
10% by weight of a mixture of CglO oxo alcohols and
C12-18 fatty alcohols + 5 EO + 13 PO (ratio 1:1)
8.3) 90% by weight of Dehydol LS 2
10% by weight of a mixture of C8l8 fatty alcohols and
mineral oil (ratio 1:1) + approximately 2% by weight
of aluminium stearate
8.4) 90% by weight of Dehydol LS 2
10% by weight of C12l4 fatty alcohol + 2 EO + 4 P0
2 1 ~2778
8.5) In addition, the foam inhibitor according to 8.4j -
Cl2l4 fatty alcohol + 2 EO + 4 PO - was tested on its
own, i.e. without the Dehydol LS 2, for comparison.
(EO = ethylene oxide units, PO = propylene oxide units)
Quantities of 2 g of mixtures/compounds 8.1) to 8.5)
were mixed with 400 g of the bentonite suspensions de-
scribed above and the resulting mixtures were subjected
to mechanical stressing, i.e. treated for 1 minute with
a Multimixer.
To evaluate the foaming of the mixtures, their
specific densities were then determined at 25C (D25). In
addition, the gel strengths of the mixtures were deter-
mined after ageing for 16 hours at around 120C (the
measurements were carried out in a Fann 35 viscosimeter).
The specific densities of the pure bentonite suspen-
sions, i.e. with no additives, were determined as blank
values:
8.6) Blank value I: specific density of the deaerated
bentonite suspension before the Multimixer treatment
8.7) Blank value II: specific density of the bentonite
suspension after the Multimixer treatment (as
. described above)
The results obtained - specific densities D25 and gel
strengths - are set out in Table 8 below:
- ` 215277~
Table 8
Example D25 Gel st-ength
10 secs. 10 mi~s.
8.1 0.9310 42 37
8.2 0.8950 47 40
8.3 0.8812 44 38
8.4 0.9033 43 36
8.5 0.8401 42 37
8.6 (Blv. I) 1.0212 - -
8.7 (Blv. II 0.775
The above results show that a particularly good
foam-inhibiting effect is developed in particular by the
C16 Guerbet alcohol (Example 8.1) and by the adduct of E0
and P0 with C1214 fatty alcohols (Example 8.4).
