Note: Descriptions are shown in the official language in which they were submitted.
2047697
"The use of selected ester oils of low carboxylic acids in drilling
fluids"
The invention discloses new drilling fluids based on ester oils and
invert drilling mulls muilt up thereon, which are distinguished by high
ecological acceptability and at the same time good keeping and
application properties. An imQortant area of application for the new
drilling fluid systems ~s in off-shore web s for the develognent of
' petroleum and/or natural gas deposits, the aim of the invention being
particularly to make available technically usable drilling fluids with
high ecological acceptability. The use of the new drilling fluid
syst~ns has particular significance in the marine environment, but is
not limited thereto. The new mud systems can be put to quite general
use e~:en in land-based drilling, for example, in geothermal wells,
water boreholes, in the drilling of geoscientific bores and in drilling
for the mining indiatry. Here too it is essentially true that
associated ecotoxic problems are substantially simplified by the ester-
base drilling oil fluids selected according to the invention.
Oil-base drilling fluids are generally used as so-called invert-
emulsion mulls, which consist of a three-phase system: oil, water and
finely particulate solids. These are preparations of the W/O enulsion
type, i.e. the aqueous phase is distributed as a heterogeneous fine
dispersion in the continuous oil phase. A number of additives can be
used to stabilize the system as a whole and to adjust the desired
~~oplication properties, particularly emulsifiers or emulsifier systems,
weighting agents, f laid=loss additives, alkali reserves, viscosity
regulators and the like. For details, refer, e.g., to the publication
by P.A. Boyd et al. "New Base Oil Used in Laa-Zbxicity Oil Mulls"
Journal of Petroleum Technology, 1985, 137 to 142, and R.B. Hennett,
"New Drilling Fluid Technology - Mineral Oil Mud" Journal of Petroleum
Technology, 1984, 975 to 981 and the literature cited therein.
The relevant technology has for some time re ognized the importance of
2047697
- 2 - __
ester-base oil phases in reducing the problems caused by such oil-base
mulls. For example, US Patent Specifications 4,374,737 and 4,481,121
disclose oil-base drilling fluids in which non-polluting oils are to be
used. 'The following are mentioned as non-polluting oils of equal value
- mineral oil fractions free from arrxnatic hydrocarbons and vegetable
oils such as peanut oil, soybean oil, linseed oil, corn oil, rice
oil or even oils of animal origin, such as whale oil. Without
exception, these named ester oils of vegetable and animal origin are
triglycerides of natural fatty acids, which are lmawn to have a high
environmental acceptability, and- are clearly superior from the
ecological viewpoint when oayared with hydrocarbon fractions - even
Interestingly enough, however, none of the examples in the
aforementioned US Patent Specifications describes the use of
such natural ester oils in invert-drilling fluids such as
those in question here. In all cases, mineral oil fractions
are used as the continuous oil phase. Oils of vegetable
and/or animal origin are not considered for reasons of
practicality. The Theological properties of such oil phases
cannot be controlled for the wide temperature range reaching
from 0 to 5°C on the one hand up to 250°C on the other hand,
which is widely required in the industry.
In use, ester oils of the type in question do not in fact behave in the
same way as the mineral oil fractions based on pure hydrocarbons which
were previously used. Est a r oils are subject to partial hydrolysis in
practical use also and particularly in W/0 invert drilling raids. Fee
carboxylic acids are formed as a result. The publications
DE 38 42 659 and DE 38 42 703 describe the problems caused
thereby and give suggestions for their solution.
The subject of these publications is the use of ester oils
based on selected monocarboxylic acids or monocarboxylic
acid mixtures and monofunctional alcohols with at least 2,
and preferably with at least 4 carbon atoms. The
publications show that with the esters and ester mixtures
they disclose, monofunctional reactants can
r
- 3 -
not only be given satisfactory theological properties in fresh
drilling fluid, but that by using selected known alkali reserves it is
possible to work with the drilling fluid and in this way to inhibit
undesirable corrosion. For the alkali reserve, one can add calcium
hydroxide or lime and/or use zinc oxide or comparable zinc compounds.
However, in this case an additional restriction is advisable. If
undesired thickening of the oil-base invert-mud system is to be
prevented in practical use, the arount of alkalizing additive and in
particular the amount of lime must be limited. The tnaxitrnun amount
provided is set at about 2 lb/bbl oil-base mud in the disclosure of the
aforementioned publications.
' The teaching of the present invention intends to avoid the problems
described above by using in the drilling fluids of the afor~nentioned
type a class of ester oils which forms non-problematical carboxylic
acids and carboxylic-acid salts during the limited ester hydrolysis
which always occurs. This idea can be technically realized by the
selection of estar oils which are based on lower carboxylic acids with
1 to 5 carbon atcens. The corresponding esters from acetic acid are
particularly significant here. The acetate salts which form
during the partial hydrolysis of the ester oil do not have
the emulsifying properties which could substantially disturb
the W/O system.
The subject of the invention is accordingly, in a first embodiment, the
use of esters, fluid at roots tgtperature and having flash points above
80oC, frcen Cl_5-tronocarboxylic acids and tmno- and/or polyfunctional
alo~hols as the oil phase or as a catponent of the oil phase of invert-
drilling mulls, which are suitable for an environment-frietxlly
development of petroleum or natural gas deposits, and in a continuous
oil phase contain a dispersed aqueous phase together with emulsifiers,
weighting agents, fluid-loss additives and preferably further
vonventional additives.
In a further gtibodiment the invention relates to invert-drilling fluids
which are suitable far the purpose itxLicated and vont,ain, in a
continuous oil phase, - a dispersed aqueous phase together with the
additives mentioned, and which are characterized in that the oil phase
vonsists at least partly of the above esters of C1_5-tmonocarboxylic
2047697
- 4 -
acids with mono- and/or polyfunctional alcohols.
The substance properties of the monocarboxylic acid esters of the type
referred to in the invention can be so controlled by the selection of
the alcohol ocer~onents used for the esterification, that it is possible
to use them as described in the invention. Corresponding esters or
ester mixtures are preferably used which are fluid and pumpable even in
the temperature range of 0 to 5°C. It is also preferred to use as the
oil phase C1-5-monocarboxylic acid esters or their admixtures with
ecologically acceptable ooa~onents frcm the class of so-called non-
polluting oils, which in the temperature range of 0 to 5°C possess a
Brc~~kfield (RVT) viscosity of not above 50 mPas and preferably not
above 40 mPas. The viscosity of the oil phase is preferably at most
about 30 mPas.
The C1_5-carboxylic-acid esters used in the drilling mud of the
invention usefully have solidification values (pour~and setting point)
below 0°C, preferably below -5°C and particularly below -
10°C. At the
same time, particularly for safety reasons, the flash points of these
esters are to be selected as high as possible so that preferred limit
values for the flash point lie at about 90°C and preferably above
100oC.
The esters of the lower carboxylic acids suitable according to the
invention can be divided into two sub-classes. In a first class the
lower monocarboxylic acids are reaction products of monofunctional
aloohols. In this case the carbon number of the alcohol is at least 6,
but is preferably higher, i.e. at least 8 to 10 carbon atoms. The
second sub-class of the ester oils referred to here uses polyfunctional
aloohols as the ester-forming ax~ponents. Particularly to be~
considered here are di- to tetra-hydric alcohols, lower alcohols of
this type, preferably with 2 to 6 carbon atcans, being particularly
suitable. Typical exar~les of such poly-hydric aloohols are glycol
and/or propanediols. Both ethylene glycol and 1,2-propanediol and/or
1,3-propanediol are particularly important. In the case described here
of esters of polyhydric alcohols, completely esterified reaction
products are preferred, even though the invention - in particular in
the case of the polyfunctional aloohols - is not limited thereto. In
20476~J7
- 5 -
the latter case in particular, the use of partial esters of such hiker
valency polyfunctional alcohols with the lower carboxylic acids
mentioned can be considered.
The most in~ortant esters for the teaching of the invention are derived
from monocarboxylic acids with 2 to 4 carbon atoms, with acetic acid,
already mentioned, being of particular importance as the ester-forming
c~r~onent.
When selecting the appropriate aloohols it is important tc~ take account
of the following additional considerations: When the ester oil is used
in practice, as a rule it is not possible to exclude paotial
saponification of the ester. Free alcohols form, in addition to the
free carboxylic acids thus formed or carboxylic acid salts forming
together with the alkali reserves. They should be selected such that
even after partial hydrolysis operational conditions are ensured which
are ecologically and toxicologically harmless, with inhalation-
toxioological considerations in particular being taken into account.
The alcohols used for the ester formation should in particular possess
such a low volatility that in the free state under conditions to be
exQected in practice, they dp not result in any nuisance on the working
platform. For the class of ester oils based on very short-chain
monocarboxylic acids which are selected in the invention, it is
necessary from the outset to use oc~aratively long-chain
monofunctional alcohols, so as to reduce sufficiently the volatility of
the ester oil. The considerations discussed here are therefore
particularly important in cases in which ester oils of the type defined
in the invention are used in blends with other mixture oa~Onents, in
particular other carboxylic acid esters. In the invention it is
regarded as particularly i.~ortant in the preferred embodiment that
even after partial hydrolysis in use, the drilling fluids are
ecologically and toxicologically harmless, particularly inhalation-
toxicologically harmless under working conditions.
Suitable aloohols, particularly suitable monofunctional alcohols can be
of natural and/or synthetic origin. Straight-chain and/or branched
aloohols can be used here. The chain length in the presence of
predominantly aliphatic-saturated alcohol is preferably from 8 to 15
.. 2047697
- 6 -
carbon atcgns. In any case olefin mono- and/or poly-unsaturated
aloohols are also suitable, such as can be obtained, for example, by
the selective reduction of naturally occurring unsaturated fatty acids
or fatty acid mixtures. Olefin-mono- and/or poly-unsaturated alcohols
such as this can also have higher carbon numbers in the ester oils
according to the invention, for example, up to 24 carbon atoms.
Ester oils of the type mentioned here can form the whole of the
continuous oil phase of the W/O invert mud. On the other hand there is
an industrial process in the scope of the invention in which the
carboxylic-acid esters defined in the invention only constitute a
mixture oampor~ent of the oil phase. Practically any of the oil
~onents previously known and/or previously described in the relevant
area of application are suitable as further oil ~rponents.
Particularly suitable mixture oaiponents will be discussed below.
The ester oils according to the invention are as a rule harogeneously
miscible with the mixture ~onents in any desired mixture ratios. ~It
is useful in the framework of the invention for at least about 25 % and
particularly at least about a third of the oil phase to be in the form
of the C1_5-ester oils. In important embodiments of the invention
these ester oils form the main part of the oil phase.
Mixture oallQonents in the oil phase
Suitable oil oo~ponents for admixture with the monocarboxylic acid
esters of the invention are the mineral oils currently used in practice
in drilling fluids, and preferably the aliphatic and/or cycloaliphatic
hydrocarbon fractions essentially free frail amnatic hydrocarbons and
which the required rheological properties. Refer here to
the prior-art publications cited and the available
commercial products.
Particularly important mixture axiponents are, however, ester oils with
are ecologically acveptable _when used acoordi~g to the invention, as
-described, for example, in the above publications DE 38 42
659 and DE 38 42 703.. To complete the invention disclosure,
essential characteristics of these esters or ester mixtures
'~' ; are briefly summarized below.
2047697
_ , _ __
As the oil phase, in a first embodiment, esters are used of
monofunctional alcohols with 2 to 12, particularly with 6 to 12 carbon
atoms and aliphatic-saturated monocarboxylic acids with 12 to 16
carbon at~xns, which esters are fluid and pu~able in the temperature
range of 0 to 5°C, or an admixture thereof with at rrost about the same
amounts of other monocarboxylic acids. E st a r oils are preferred which
at least to about 60 % by weight - referred to the respective
carW xylic acid mixture - are esters of aliphatic C12-1~-monocarboxylic
acids and preferably for the remaining percentage are based on lower
amounts of shorter-chain aliphatic and/or longer chain, and in
particular olefin mono- or poly-unsaturated monocarboxylic acids.
. Esters are preferably used which in the temperature range of 0 to 5°C
have a Brookfield (RVT) viscosity of not above 50 mPas, preferably not
above 40 mPas and particularly of a ma~curnun of about 30 mPas. The
esters used in the drilling mud have solidification values (pour and
setting point) below -10°C, preferably below -15°C and have at
the same
time flash points above 100°C, preferably above 150°C. The
carboxylic
acids present in the ester or ester mixture are straight-chain and/or
branched and are of vegetable and/or synthetic origin. They can be
derived fratn corresponding triglycerides such as coconut oil, palm
kernel oil and/or babassu oil. The alcohol radicals of the esters used
are derived in particular from straight-chain and/or branched saturated
alcohols preferably with 6 to 10 carbon atoms. These alcohol
oa~onents can also be of vegetable and/or animal origin and can thus
be obtained by reductive hydration of corresponding carboxylic acid
esters.
A further class of particularly suitable ester oils is derived from
olefin mono- and/or poly-unsaturated monocarboxylic acids with 16 to 24
carbon atoHns or their admixtures with lager amounts of other
particularly saturated monocarboxylic acids and monofunctional aloohols
with preferably 6 to 12 carbon atans. These ester oils are also fluid
and pumpable in the terperature range of 0 to 5°C. Particularly
suitable are such esters derived to more than 70 % by weight,
preferably to more than 80 % by weight and in particular to more than
90 % by weight from olefin-unsaturated carboxylic acids with between 16
and 24 carbon atoms. _
2047697
- 8 - __
Here too the solidification values (pour and setting point) lie below -
lOoC, preferably below -15°C while the flash points lie above 100oC and
preferably above 160°C. In the ter~erature range of 0 to 5°C the
esters used in the drilling mud have a Brookfield (RVT) vis<_rosity of
not rrore than 55 mPas, preferably not more than 45 mPas.
~o subclasses can be defined for the ester oils of the type in
question. In the first, the unsaturated C16-24-m°n~°xYlic acid
radicals present in the ester are derived tc~ not more than 35 % by
weight frcm olefin di- and poly-unsaturated acids, with preferably at
least about 60 % by weight of the arid radicals being olefin mono-
unsaturated. In the second gnbodiment the C16-24-~~~X1'lic acids
present in the ester mixture are derived at more than 45 % by weight,
preferably at mire than 55 % by weight fran olefin di- and/or poly-
unsaturated acids. It is useful if the saturated carboxylic acids with
between 16 to 18 carbon at~ns which are present in the ester mixture do
:got amount to more than about 20 % by weight and in particular not more
than about 10 % by weic~t. Preferably, saturated carboxylic acid
esters, however, have lower carbon numbers in the acid radicals. The
cari~oxylic acid radicals present can be of vegetable and/or animal
origin. Vegetable starting materials are, for. exanple, palm oil,
peanut oil, castor oil and in particular rapeseed oil. The carboxylic
acids of animal origin are particularly corresporxiing mixtures of fish
oils, such as herring oil.
Suitable mixture catponents are finally however the esters from
mc~nocarboxylic acids of synthetic and/or natural origin with 6 to 11
carbon atoms and mono- and/or polyfunctional alcohols,
described in the co-pending Canadian Application 2,047,706,
filed March 1, 1990 (DE 39 07 392), which are preferably
also fluid and pumpable in the temperature range of 0 to 5 °C .
E
204~69~
- __
Further mixture oorr~onents of the invert drillinq fluid
All the usual constituents of mixtures for conditioning and for the
practical uses of invert drilling roods can be considered here, that are
currently used with mineral oils as the continuous oil phase. In
addition to the dispersed aqueous phase, emulsifiers, weighting agents,
fluid-loss additives, viscosifiers and alkali reserves can be
considered here.
Use is also made in a particularly important embodiment of the
invention, of the further development of these ester oil-base invert
drilling fluids which is the subject of the Applicant's co-
pending Canadian Application 2,009,689, filed February 9,
1990 (DE 39 03 785).
The teaching of this co-pending Application is based on the concept of
using a further additive in ester oil-base invert-drilling fluids,
which is suited to keeping the desired rheological properties of the
drilling fluid in the required range even when, in use, increasingly
large amounts of free carboxylic acids are formed by partial ester
hydrolysis. These liberated carboxylic acids should not only be
trapped in a harmless form, it should moreover be possible to reform
these free carboxylic acids, preferably into valuable oarponents with
stabilizing or emulsifying properties for the whole system. According
to this teaching, alkaline amine oa~ounds of marked oleophilic nature
and at best limited water solubility, which are capable of forming
salts with carboxylic acids, can be used as additives in the oil
phase. The oleophilic amine compounds can at the same time be used at
least in part as alkali reserves in the invert drilling fluid, they can
however also be used in combination with vonventional alkali reserves,
particularly together with lime. The use of oleophilic amine varpounds
which are at least largely free from aromatic constituents is
preferred. In particular, optionally olefin unsaturated aliphatic,
cycloaliphatic and/or heterocyclic oleophilic basic amine oa~OUnds~
can be considered, which contain one or tmre N-groups capable of
forming salts with carboxylic acids. In a preferred embodiment the
water-solubility of these amine oa~unds at roan temperature is at
most about 5 % by weight and is most preferably below 1 % by weight.
_ to _ _. 2047697
Typical exiles of such amine ax~ounds are primary, secondary and/or
tertiary amines, which are at least predominantly water-insoluble, and
which can also to a limited extent be alkoxylated and/or substituted
particularly with hydroxyl groups. Further examples are corresponding
aminoamides and/or heterocycles containing nitrogen as ring
constituent. For example, basic amine oorrpounds are suitable which
have at least one long-chain hydrocar!~on radical with preferably 8 to
36 carbon atcans, particularly with 10 to 24 carbon atoms, which can
also be olefin mono- or poly-unsaturated. The oleophilic basic amine
compounds can be added to the drilling fluid -in amounts of up to about
lb/bbl, preferably in arrounts up to about 5 lb/bbl and particularly
in the range of about 0.1 to 2 lb/bbl.
It has emerged that the use of such oleophilic basic amine o~rø~ounds
can effectively prevent thickening of the mud system, which presumably
can be attributed to a disturbance in the W/O invert system and also to
the formation of free carboxylic acids by ester hydrolysis. ''
If in the context of the invention teaching, esters of longer-chain
carboxylic acids are used as mixture cocrponents, which on hydrolytic
cleavage yield fatty acids or fatty-acid salts with a pronounced O/W-
emulsifying effect, then in the method according to the invention the
measures regarding the alkali reserves should also be taken into
consideration as described in detail in the aforementioned
publications DE 38 42 659 and DE 38 42 703 in association with
such problems. When such ester mixtures are used the
following applies:
In a preferred embodiment of the use according to the invention, care
is taken not to use considerable amounts of strongly hydrophilic bases
of inorganic and/or organic nature in the oil-base mud. In particular
the invention refrains fran using alkali hydroxides or strongly
hydrbphilic amines such as diethanolamine and/or triethanolamine. Lime
can be also used effectively as an alkali reserve. It is then useful
to limit the maximum amount of lime to be used to about 2 lb/bbl, and
it may be preferred to work with lime contents in the drilling tn~d
slightly below this, e.g., therefore, frrm about 1 to 1.8 lb/bbl
(lime/drilling fluid). Other known alkali reserves can be used in
_ _
- 11 -
2A47697
addition to or in place of the lime. The less basic metal oxides, such
as zinc oxide, should particularly be mentioned here. E~ren when these
acid traps are used, care is still taken that the amounts used are not
too large, so as to prevent undesired premature ageing of the drilling
fluid, associated with an increase in viscosity and therefore a
deterioration in the rheological properties. The special features
discussed here of the process according to the invention prevent, or at
least restrict, the formation of undesirable amounts of highly active
O/W-~nulsifiers, so that the good r!~eological properties are maintained
for a sufficiently long time in use, even when there is thern~al ageing.
The following also applies:
Invert-drilling mulls of the type in question here usually contain,
together with the continuous oil phase, the finely dispersed aqueous
phase in amounts of about 5 to 45 % by weight and preferably in amounts
of about 5 to 25 % by weight. A dispersed aqueous phase from about 10
to 25 % by weight can be regarded as particularly useful.
The following rheological data apply to the rheology of preferred
invert drilling mulls according to the invention: Plastic viscosity
(PV) frown about 10 to 60 mPas, preferably about 15 to 40 mPas. Yield
point (YP) from about 5 to 40 lb/100 ft2, preferably about 10 to 25
lb/100 ft2 - each measured at 50oC. For the measurement of these
parameters, for the measuring methods used and for the rest of the
conventional oce~osition of the invert drilling fluids described here,
refer in detail to the specifications in the prior art which were cited
above and are, for example, described fully in the handbook "Manual of
Drilling Fluids Technology" of NL-Baroid Co., London, GB, particularly
in the chapters "Mud Testing - Tools and Techniques" and "Oil Mud
Technology", which is freely accessible to interested experts. In
su~y, for the purposes of oarpleting the invention disclosure the
following can be said:
The emulsifiers which can be used in practice are systems which are
suitable for the formation of the required W/O emulsions. In
particular, selected oleophilic fatty acid salts, for example, those
based on amidoamine oortpounds can be considered. Examples of these are
-. 2p47697
- 12 - --
described in the already cited US-PS 4,374,737 and the literature cited
there. A particularly suitable type of emulsifier is the product sold
by NLrBaroid Co. under the trade-mark "EZ-mul" .
Emulsifiers of the type in question are sold a~mercially as highly
concentrated active-substance preparations and can, for example, be
used in amounts of about 2.5 to 5 % by weight, particularly in amounts
of about 3 to 4 % by weight - each based on the ester oil phase.
In pracrice, hydrophobized lignite in particular is used as the fluid-
loss additive and therefore particularly for forming a dense coating on
the- bore-hole walls of a largely liquid-impermeable film. Suitable
amounts are, fob example, from about l5 to 20 lb/bbl or frcan about 5 to
7 % by weight, based on the ester oil phase .
The visoosifier conventionally used in drilling fluids of the type in
question here, is a ration-modified finely particulate bentonite, which
can be used particularly in amounts of about 8 to 10 lb/bbl or frnm
about 2 to 4 % by weight, based on the ester oil phase. The
weighting material conventionally used in relevant applications to
establish the necessary pressure vompensation is barite, and the
amounts added are varied according to the drilling conditions
anticipated in each case. It i$, for exanple, possible by adding
barite to raise the specific gravity of the drilling fluid
to values up to 2.5 and preferably from about 1.3 to 1.6.
The dispersed aqueous phase in these invert drilling fluids, is loaded
with soluble salts. Calcium chloride and/or potassi,.un chloride are
mainly used here, and saturation of the aqueous phase with the soluble
salt at room tatperature is preferred.
The aforementioned emulsifiers or emulsifier systems can optionally
also be used to improve the oil wettability of the inorganic weighting
materials. In addition to the aminoamides already mentioned, further
exanples are alkylbenzene sulfonates and imidazoline compounds.
Additional inforn~ation regarding the relevant prior art can be found in
the following publications: CB 2 158 437, EP 229 912 and DE 32 47 123.
- 13 -
2047697
The drilling fluids synthesized according to the invention using ester
oils of the type described are distinguished, in addition to the
advantages already described, by a notably i~roved lubricity. This is
particularly important when in very deep wells, for example, the path
of the drill rod and therefore the borehole deviates frcen the vertical.
The rotating drill rod oo~nes slightly into contact with the borehole
wall and when operating buries itself into it. Ester oils of the type
used as the oil phase according to the invention have a notably better
lubricity than the mineral oils previously used. This ~s another
imQortant advantage of the method according to the invention.
-14-
E~~es
In the following examples invert drilling fluids are prepared in the
conventional manner using the following basic fornlulation:
230 ml ester oil
26 ml water
TM
6 g organophilic bentonite (Geltone II of NL Baroid Co.)
TM
12 g organophilic lignite (Duratone of NL Baroid Co.)
x g lime (x = 1 or 2)
6 g W/O emulsifier (EZ-mul NT of NL Baroid Co.)
346 g barite
9.2 g , CaCl2 x 2 H20
In this formulation about 1.35 g of lime corresponds to 2 lb/bbl.
After a W/O invert drilling fluid has been prepared in a lmc~m manner
from the components used, with variation of the ester oil phase, the
viscosities of the unaged and then the aged material arA determined !as
follows:
TM
Measurement of the viscosity at 50°C in a Fann-35-viscosimeter
supplied
by NL Baroid Co. The plastic viscosity (PV), the yield point (YP) and
the gel strengths (lb/100 ft2) are determined in a Imown manner after
sec. and 10 min.
Ageing is carried out by treatment in autoclaves - in the so-called
roller-oven - for a period of 16 hours at 125°C.
Isotridecyl acetate which has the following rheological characteristics
is used as the ester oil: viscosity at 20oC 5 mPas; viscosity at 50oC
2.1 mPas; setting point below -lOoC.
In Exanple 1 below, the amount of lime used in the basic formulation is
2 g, in F~ple 2 this lime amount is reduced to 1 g.
The values determined for the unaged and aged material are listed in
the following table.
W
_2A47697
- 15 -
unaged material aged material
plastic viscosity (PV) 31 33
yield point (YP) 11 13
gel strengths (lb/100 ft2)
1C sec. 6 7
min. 9 9
Example 2
unaged material aged material
plastic viscosity (PV) 24 25
yield point (YP) 14 12
gel strengths (lb/100 ft2)
10 sec. 5 5
10 min. 8 7
The basic formulation in Exa~les 1 and 2 has a value of 90/10 for the
oil phase/water weight ratio. In further tests the the ester oil/water
ratio is changed to 80/20.
In Examples 3 and 4 below, invert drilling fluids are prepared using
the ester oil based on isotridecyl acetate, according to the following
basic forniulation:
210 m1 ester oil
48.2 g water
TM
6 g organophilic bentonite (Q~igel)
13 g or.ilic lignite (Duratone of I~ Bar~oid Co.)
2 g lime
8 g W/0-~ulsifier (EZ-mul NT of NL Baroid Co.)
270 g barite
g CaCl2 x 2 H20
As in Exanples 1 and 2, the viscosities are determined first on the
unaged, then on the aged material (16 hours at 125°C in the roller
oven) (Exanple 3). .
2a47697
- 16 - --
In a further test formulation (ale 4), 2 g of a strongly oleophilic
amine is added to the basic formulation given for ale 3
TM
(Applicant's oonmercial product "Araphen G2D" - the reaction product of
an epoxidized C12/14-alpha-olefin and diethanolamine). The viscosity
characteristics are then determined as above first on the unaged and
then on the aged material.
ale 3
unaged material aged material
plastic viscosity (PV) 34 36
yield point (YP) 52 51.
gel strengths (lb/100 ft2)
sec. 25 23
10 min. 37 35
F~cample 4
unaged material aged material
plastic visvosity (Ptl) 31 34
yield point (YP) 36 32
gel strengths (lb/100 ft2)
10 sec. 14 13
10 min. 17 15
E~cample 5
The ester-mixture fran acetic acid and a C6_10'aloohol cut (Applicant's
TM
ocmmercial product "Lorol'technisch"), prepared by the reduction of the
corresponding pre-fatty-acid cut of natural origin, is used as the
ester oil. The basic forn~ulation for the ester mud corresponds to the
fornailation given for ~anple 2.
The visvosity data are determined and the ageing is carried out as
indicated in the previous acanples. The following visoosities are
- 17 -
determined. 2 ~ 4 7 6 9 7
unaged material aged material
plastic visvosity (PV) 28 29
yield point (YP) 17 20
gel strengths (lb/100 ft2)
sec. g g
10 min. 24 14
~~~les 6 to 8
In parallel formulations, three drilling fluids based on isotridecyl
acetate are produced according to the basic formulation in Exanples 1
and 2 (oil phase/water = 90/10). As in the preceding ales, their
rheological data was determined im~iately after preparation and after
ageing in the roller oven at 125oC for a period of 16 hours.
In a first mud, no lime is added (ale 6), in a second mud (ale
7) 2 g of lime is used, while in the parallel third mud (ale 8) 2 g
of lime is used together with 1 g of the strongly oleophilic amine
"Araphen G2D".
The rheological data determined in each case are as follows:
- 18 -
~1e6 2047697
unaged material aged material
plastic viscosity (PV) 28 30
yield point (YP) 15 9
gel strengths (lb/100 ft2)
sec. y
10 min. 10 8
ale 7
unaged material aged material
plastic viscosity (PV) 30 29
yield point (YP) 13 17
gel strengths (lb/100 ft2)
10 sec. g g
10 min. 10 12
F~cample 8
unaged material aged material
plastic viscosity (PV) 25 25
yield point (YP) 12 8
gel strengths (lb/100 ft2)
10 sec. g
10 min. 11 9
les 9 to 11
In a further oca~arative series of tests, drilling fluids based on
isotridecyl acetate are vombined in the basic formulation of E~camples 6
to 8 as follows: bcanple 9 addition of 1 g of lime; ale 10 addition
of 2 g of lime; Ele 11 addition of 2 g of lime + 1 g of "Araphen
G2D".
- 19 -
2o4~ss~
These mulls are then aged, however, in the roller oven at 125°C
for a
period of 72 hours. The rheological data determined on the unaged and
aged material in each case are as follows:
Example 9
unaged material aged material
plastic viscosity (PV) 30 37
yield point (YP) 15 16
gel strengths (lb/100 ft2)
sec. 7 7
10 min. 11 10
Example 10
unaged material aged material
plastic viscosity (PV) 28 34
yield point (YP) 16 13
gel strengths (lb/100 ft2)
10 sec. 6 6
10 min. 10 10
Example 11
unaged material aged material
plastic viscosity (PV) 29 36
yield point (YP) 11 14
gel strengths (lb/100 ft2)
10 sec. 7 6
10 min. 10 10
