Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02050935 2001-03-14
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~05~1935
"The use of selected ethers of monofunctional alcohols in drilling
fluids"
The invention discloses new drilling fluids and invert drilling mulls
based thereon, which are distinguished by high ecological acceptability
and at the same time good storage and application properties. An
important area of application for the new drilling fluid systems is in
off-shore wells for the development of petroleum and/or natural gas
deposits, the aitn of the invention being particularly to make available
industrially usable drilling fluids with high ecological acceptability.
The use of the new drilling fluid systems has particular significance
in the marine environment, but is not limited thereto. The new mud
systems can be put to quite general use even in land-based drilling,
for example, in geothermal wells, water bore-holes, in the drilling of
geoscientific bores and in drilling.for the mining industry. Here too
it is essentially true that associated ecotoxic probleqns are
substantially sircplified by the ester-based drilling-oil fluids
selected aca>rding to the invention.
The Prior Art
Oil-base drilling fluids are generally used in the form of 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-
e~nulsion 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 syst~ as a whole and to confer on it the
desired application properties, particularly emulsifiers or emulsifier
systems, weighting agents, fluid-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 Iaw-Toxicity Oil
Mulls" Journal of Petroleum Technology, 1985, 13? to 142, and R.B.
Bennett, "New Drilling Fluid Technology - Mineral Oil Mud" Journal of
Petroleum Technology, 1984, 975 to 981 anti- the literature cited
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therein.
The i~ortance of ester-based oil phases in reducing the problems
created by such oil-base muds has been recognized for scene time in the
relevant field of technology. 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 follc7wing are of equal value as the
non-polluting oils - mineral oil fractions which are free from araratic
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. These named ester oils of vegetable and animal origin are
all, without exception, triglycerides of natural fatty acids, which are
lmown to be of high environmental acceptability, and are clearly
superior ecologically to hydrocarbon fractions- even when these do not
contain aromatic hydrocarbons.
Interestingly enough, however, not one of the~exat~les in the above US
Patent Specifications describes the use of such natural ester oils in
invert-drilling fluids of this type. In every case, mineral oil
fractions are used as the continuous. oil phase. Oils of vegetable
and/or animal origin are not vonsidered for practical reasons. The
rheological properties of such oil phases cannot be controlled over the
wide temperature range generally required in practice, fret 0 to 5°C on
the one hand, up to 250°C on the other.
The Applicant's other proposals
Ester oils of the type in question d4 not in fact behave in the 'same
way in practice as the previously used mineral oil fractions based on
pure hydrocarbons. Ester oils are subject to partial hydrolysis in
practical use, particularly in w/O-invert drilling mode. Fret
carboxylic acids are formed as a result. The Apphicant's co-pending
Canadian Applications 2,006,009 and 2,006,010, filed December 19,
1989 describe the problems caused thereby and give proposals for
their solution. Further types of usable ester oils are disclosed in
' the co-pending Canadian Patent Applications 2,047,697 and 2,047,206,
filed March 1, 1990. -
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The subject of these co-pending Applications is the use of ester
oils based on selected monocarboxylic acids or monocarboxylic acid
mixtures and monofunctional, and optionally polyfunctional, alcohols. The
co-pending Applications show that, with the esters and ester mixtures they
disclose, it is not only possible to invest fresh drilling fluid with
satisfactory rheological properties, but it is also possible to use
selected ~a~m alkali reserves in the drilling fluid and in this way to
retard undesirable corn~sion. As alkali reserves - particularly when
ester oils based on carboxylic acids with at Least 6 carbon atoms are
used - calcium hydroxide, or lime, can be added and/or can be used with
zinc oxide or oa~arable zinc catpounds. In this case, however, an
additional restriction is advisable. To prevent unwanted thickening of
the oil-base invert mud system in practical use, the amount of
alkalizing additive, and in particular the amount of lime, must be
limited. The maxim~t amount permitted in the disclosure of the
aforementioned co-pending Applications is about 2 lb/bbl
(pounds/barrel) of oil-base muds.
An important further development of these invert-drilling fluids
based on ester oils is the subject of the Applicant's co-pending
Canadian Applications 2,009,689, filed February 9, 1990.
The teaching of this co-pending Application is based on the concept of
using a further additive in the invert drilling fluids based on ester
oils, which is suited to keeping the desired rheological properties of
the drilling fluid within the required range, even when ever larger
amounts of free carboxylic-acids are formed in use by partial ester
hydrolysis. These liberated carboxylic acids should not only be caught
in a harmless forth, it should m?reover be possible to convert these
free carboxylic acids, preferably into valuable ;cxx~ponents with
stabilizing or emulsifying properties for the whole system. According
to this teaching, basic amine ocnpounds of marked oleophilic hature and
at most limited water solubility, which are capable of forming salts
with carboxylic acids, can be used as additives in the oil phase. The
oleophilic amine ccarpounds 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 occ~ination with conventional alkali reserves,
particularly together with lime. The use of oleophilic amine oc~pounds
CA 02050935 2001-03-14
4 _
which are at least largely free frcm arc~natic constituents is
preferred. In particular, optionally olefin-unsaturated aliphatic,
cycloaliphatic and/or heterocyclic oleophilic basic amine compounds,
can be considered, which contain one or more N-groups capable of
forming salts with carboxylic acids. In a preferred ~nbodiment the
water-solubility of these amine compounds at room temperature is at
most about 5 ~ by weight and is usefully below 1 ~ by weight.
Typical examples of such amine cc~ounds are primary, secondary and/or
tertiary amines, which are at least largely water-insoluble, and which
can also to a limited extent be alkoxylated and/or substituted,
particularly with hydroxyl groups. Further examples are the
corresponding aminoamides and/or heterocyclic compounds with nitrogen
as a ring constituent. For example, basic amine compounds are suitable
which have at least one long-chain hydrocarbon radical, preferably of
from 8 to 36 carbon atoms, particularly with 10 to 24 carbon atoms,
which can also be olefin mono- or poly-unsaturated. The oleophilic
basic amine o~npounds can be added to the drilling fluid in amounts of
up to about 10 lb/bbl, preferably in amounts up to about 5 lb/bbl and
particularly in the range of about 0.1 to 2 lb/bbl.
It has been found that the use of such oleophilic basic amine ooa~ounds
can effectively prevent thickening of the mud systean, which presumably
can be attributed to a disturbance of the W/O invert systeqn and also to
the formation of free carboxylic acids by ester hydrolysis.
The invention problegn and its technical solution
The probleqn of the present invention is further to develop syst~ns of
the type in question and in particular drilling fluids of high
ecological acceptability. In a first embodiment the invention proposes
to make available oils and oil mixtures for the production of drilling
fluids based on W/O-emulsions, which can be used industrially and are
easily accessible and at the same time are distinguished by high
ecological acceptability. In a further eqnbodimPxit the invention
intends to make available additives for the afor~entioned systems in
question here, which confer valuable additive properties on drilling
fluids based on W/O-e~milsions without having a disadvantageous effect
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on their ecological acceptability.
The technical solution of the problems of the invention starts frown the
Imowledge that selected ethers suited to this use can result in new and
improved drilling fluids of the type described. These ethers are
water-insoluble or essentially water-insoluble ~onents, in
particular therefore oorrespondi.ng oampounds with a pronounced
oleophilic nature, which differ, however, frown pure hydrocarbon
c~ounds by the presence of the functional ether group. As a result
important technological improvements can be made and at the same time
high ecological acceptability is ensured.
The subject of the invention is accordingly, in a first embodiment, the
use of water-insoluble ethers, with flash points above 80°C, of
monohydric aloohols of natural and/or synthetic origin with at least 4
carbon atcms, preferably at least 6 carbon atcgns in the alcohol
radicals, as the oil phase, or a constituent of the oil phase, of
invert-drilling fluids, which exist as W/O-emulsions and which, in the
continuous oil phase, which is fluid and pumpable in the temperature
range of 0 to 5 °C, have a dispersed aqueous phase and preferably
further usual additives and which are suitable for the environmentally
acceptable develo~ent of, for e~le, petroleum or natural gas
deposits.
In a further embodiment the invention relates to invert drilling
fluids, as described above, which are characterized in that they
contain, as a continuous oil phase or dissolved in ecologically
acceptable oils, an additive which consists at least pred~i.nantly of
water-insoluble ethers of monohydric alcohols, such that the respective
oil phase is fluid and pumpable in the temperature range of 0 to 5°C
and has flash points above 80°C.
The various embodiments of the invention
In a first embodiment the continuous oil phase of the invert drilling
fluids i_s formed exclusively, or to by far the larc~st part, by the
essentially water-insoluble and preferably markedly oleophilic ethers.
Understandably, the rheology of the ethers used here must be suited to
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a. .. 6 ..
the technical requirements of the drilling fluids. Slight rheological
adjustments are possible by adding small amounts of the diluents
provided in this embodiment. In the case described here, in particular
oil phases can be considered, which are forn~ed by more than 70 ~ by
weight, preferably by more than 80 ~ by weight, and desirably
exclusively, by the ethers themselves. The general subject lmowledge
is applicable for the rheological requirements of such oils for use in
drilling fluids, and this will be discussed again below.
The definition according to the invention of the term "suitable ethers"
includes quite common symmetrical ethers, derived fran a selected
alcohol, mixed ethers from different alcohols and/or ether mixtures of
the twr~ ether types mentioned above. From the broad range of suitable
individual ethers or mixed ethers and/or ether mixtures, those agents
can be considered in particular which are at least in part the
corresponding derivatives of monofunctional alcohols with at least 6 to
7 carbon atoms, preferably with at least 8 carbon atoms, the possible
upper limit of the carbon number being greatly influenced by the
structure of the hydrocarbon radical. The lmown effect of branched-
chain and/or un-saturated structure of a hydrocarbon radical in
corresponding alcohols also influences the rheology of the ethers
formed therefrcan.
The rheology of branched-chain and/or unsaturated ethers of the type in
question here is lmoHm to meet the reduirements of flowability and
pumpability, even at lower te~eratures, mare easily than the straight-
chain saturated hydrocarbon structure. Saturated straight-cha;n fatty-
aloohol-ethers with from 16-18 carbon atc~tis are imawn to have high
setting ranges. Branched ethers of the same carbon-number range can -
depending on the extent and degree of branching - constitute completely
acceptable fluid and pumpable oil phases in the sense of the invention.
In the field of saturated ethers frcem monofunctional alcohols, the
range with low numbers of carbon atoms is particularly suitable,
particularly therefore the range of about 8 - 14 carbon atcens, here too
the ethers from branched-chaW alcohols can have rheological
advantages.
The oil-mixture vents optionally used in small amounts in this
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embodiment can be pure hydrocarbon ccxrpounds especially those free from
aromatic hydrocarbons, in particular selected ester oils of the type
described in the Applicant's co-pending Applications mentioned above.
The rheological properties of the ether oa~onents used according to
the invention beoa~e less and less important, the greater the
proportion of these mixture constituents in the ac~nixture with one or
more oil ccmponents. A second embodiment of the invention relates
accordingly to the use of oil phases in systems of the type in question
which still have considerable or even predominant amounts of non-water-
miscible oils, which are used in admixture with the ethers provided
according to the invention. The ether content selected according to
the invention in this embodiment is as a rule more than 10 % by weight
and up to about 70 % by weight - each referred to the fluid oil phase -
and ether fractions in amounts of at least about 35 % by weight and
preferably at least about 50 % by weight of the oil phase may be
pref erred .
As the mixture components for this second embodiment of the invention,
there can again be considered both pure hydrocarbon oils, particularly
those free frcm aromatic hydrocarbons, and especially ester oils of the
type described in the co-pending Applications by the Applicant. Such
admixtures also fall within the framework of the invention, with both
admixtures of ester oils with pure hydrocarbon carpounds and mixtures
of various ester oil types possible for use as mixture vents for
general use with the oleophilic ethers. In preferred embodiments of
the invention, the pure hydrocarbon oils with no functional groups at
all are used in the oil phase in amounts of at most 50 % by weight,
preferably of at mist about 35 % by weight and particularly in amounts
of at most about 25 % by weight - each referred to the oil phase. In
the most important ~diments of the variants described here, mixtures
of the ethers and ester oils defined according to the invention are
used as the oil phase without the addition of pure hydrocarbon
,..
The invention finally relates in a third variant to the use of
practically water-insoluble=ethers as additives in the oil phase of the
aforementioned drilling fluids based on w/O-emulsions. The amount of
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ethers used according to the invention is usually in the range of about
0.1 to a maximnun of 10 % by weight; preferably in the range of about 1
to 5 % by weic~t of the oil phase. The range of suitable water-
insoluble ethers can understandably be enlarged substantially in this
ercibodiment. The rheology of the system as a whole is no longer
determined here by the rheological values of the ether. It is in this
embodiment that the use of the ethers defined according to the
invention as additives achieves important improvements in the behaviour
of drilling fluids of the aforementioned type.
This is true in particular for invert systems in which the main
oa~ponent of the continuous oil phase is formed exclusively or
primarily by ester oils of the type described in the above co-pending
Applications of the Applicant. In the embodiment in question here, the
oil phase is constituted accordingly by at least 25 % by weight,
preferably by at least 50 % by weight and particularly by at least
about 75 to 80 % by weight of the oil phase byvan ester oil as the main
component. Pure hydrocarbon oils of the prior art can be used for the
rest of the oil phase, it is however advantageous to dispense with them
altogether. .
By adding to the invert systems the water-insoluble ethers defined
according to the invention, important improveqnents can be achieved for
the practical use of the drilling fluids. The following 4 aspects are
particularly affected: reduction of the fluid-loss values, the
facilitation and improvement of the emulsification of the dispersed
aquebus phase, in some cases clearly improved lubrification by the
drilling fluid and in sane cases a distinct improvement in the
rheological properties of invert drilling fluids based on ester oils.
The ethers used acoordinct to the invention
The use of the ethers as the oil phase, but also their oa~ination as a
lesser or greater part in the oil phase, rern,?res these ethers to have
adequate water-insolubility. The water-solubility of suitable ethers
at roan temperature preferably lies below 5 % by weight, particularly
under 1 % by weight and preferably not more than about 0.1 % by weight.
a, _
.~_,~
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The following general rules apply for the cheqnical nature of the
ethers:
The special structure of the ethers used in the method according to the
invention is primarily determined by the embodiment selected in each
case, in which the composition of the ether-containing oil phase is
selected, see here the previous sub-section.
If the ethers form the oil phase exclusively or if the ethers are
present at least as the major mixture ~onent in the application
mixture forming the continuous oil phase, the selection of suitable
ethers or ether mixtures is initially determined by the corresponding
basic rheological data. In this case, in detail, the ether or the
ether mixtures used in the temperature range of 0 to 5oC should have a
Brookfield (RVT) viscosity not above 50 mPa.s, preferably not above 40
mPa.s and particularly at most of about 30 mPa.s. The solidification
values (pour and setting point) of the ether or ethers should at the
same time lie below 0°C. Preferably, ethers or ether mixtures are used
with solidification values below -5°C and particularly below -l0oc.
Finally, the flash points of the ether or ethers used are important for
practical use, these are advantageously not below 90°C and preferably
above 100°C. Much higher flash points, for example, those above
130°C
and in particular above 150°C, can be particularly useful.
As already discussed in the preceding sub-section, the overall nature
of the rheological properties and the flash point is greatly determined
by the individual mr~lecular structure of the ether-forming alcohols.
These structural features are discussed below:
An important element of the invention is the use of c~aratively non-
toxic components, as a result the use, for example, of aromatic ethers
in particular of the phenol ether type is therefore practically
excluded. Aliphatic, optionally olefin mono- and/or poly-unsaturated
alcohols with a straight-chain and/or branched hydrocarbon structure
and also optionally cycloaliphatic aloohols are the most important
ether-forming c~ponents in the sense of the method according to the
invention. The lower limit for the number of carbon atcgns in such
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alcohols is 4 carbon atans, preferably 6 carbon atoms and particularly
8 carbon atans. The upper limit for the number of carbon atoms in the
ether-forming alcohols can also be chosen quite high depending on the
Theology requirements and lies, for exan~le, at about 36 carbon atcens,
preferably at about 32 carbon atans. In particular, monofunctional
aloohols can be considered with about 6-24 carbon atcens, preferably
from 6-18 carbon atcens. Ethers of Cg_16-alcohols and in particular Cg-
14-alcohols, are suitable components in the sense of the teaching of
the invention.
The ether-forming alcohols can be oc~npletely or at least partly
of straight-chain and/or branched-chain type, even and/or odd-numbered,
saturated and/or unsaturated. The ether-forming alcohols here can
again be ocarpletely or partly of natural and/or synthetic origin.
Within the limit conditions indicated, certain selected ethers or
ethers frcsn certain selected alcohols, mixed ethers from certain
selected aleohols and/or ether~mixtures are suitable. Since the ether
function is inert, at least to a great extent, both to the constituents
introduced with the: drilling fluid and to the chemical actions taking
place when the drilling fluid is used - this is also true in particular
for the alkalized invert W/O-based emulsions - there is almost no
restriction of choice, and therefore the Theological data required in the
drilling fluid can be set at an optina.un level and achieved. Secondary
reactions when in~ use, such as are typical for the ester oils in
alkalized W/O-invert emulsions, need not be seriously considered for
ethers used as the oil phase-or as mixture v~nents of the oil phase.
The mixture ecar~onents in the oil phase
Suitable oil components for the admixture according to the invention
are the mineral oils currently used in drilling fluids, and preferably
aliphatic and/or cycloaliphatic hydrocarbon fractions essentially free
from arcmati.c hydrocarbons, with the required Theological properties.
Refer here to the prior-art publications cited above and the available
vanrnxcial products .
Particularly important mixture oatponents, however, are ester oils
.u .
rs:,:.~,~'
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- I1- ~~50935
which are eoologica:lly acceptable as used in the invention, as
described in particular in the aforementioned co-pending
Applications 2,006,009; 2,006,010; 2,047,697 and 2,047,706. To
complete the invention disclosure, the essential characteristics of
these esters, or ester mixtures, are now briefly summarized.
In a first eqnbodiment, as the . oil phase, esters are used of
monofunctional aloohols with from 2 to 12, particularly with frc~n 6 to
12, carbon atoms and aliphatic-saturated monocarboxylic acids with from
12 to 16 carbon atoms, which [esters] are fluid and pumpable in a
te~erature range of 0 to 5°C, or an admixture thereof with at most
about the same amounts of other monocarboxylic acids. Ester oils are
preferred which are based, to at least about 60 % by weight - referred
to the respective carboxylic acid mixture -, on esters of aliphatic
X12-14-~~~xYlic acids, the remaining percentage preferably being
based on smaller amounts of shorter-chain aliphatic and/or longer-
chain, 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 mire than 50 mPa.s,
preferably not above 40 mPa. s and particularly of a ma~ci,m~un of about 30
mPa.s. The esters used in the drilling mud have solidification values
(pour and setting point) below -10°C, preferably below -15°C and
at the
same time have flash points above 100oC, preferably above I50°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 fran~the vorresponding triglycerides, such as
coconut oil, palm kernel oil and/or babassu oil. The alcohol radicals
of the esters used are derived i.n particular from straight-chain and/or
branched saturated alvohols, preferably with fran 6 to l0 carbon atone.
These alcohol oa~onents can also be of vegetable and/or animal origin
and can thus be obtained by the reductive hydrogenation of the
corresponding carboxylic acid esters.
A further class of particularly suitable ester oils i.s derived from
olefin mono- and/or poly-unsaturated monocarboxylic acids with 16 to 24
carbon atoms or their ac~nixtures with smaller amounts of other,
particularly saturated, monocarboxylic acids and monofunctional
v.~~:>
~:~r ~ -
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ahhols with preferably fran 6 to 12 carbon atans. These ester oils
are also fluid and pumpable in the temperature range of 0 to 5°C. In
particular those esters are suitable which are derived, by more than 70
% by weight, preferably by more than 80 % by weight and in particular
by more than 90 % by weight, fran.olefin-unsaturated carboxylic acids
with frcxn 16 to 24 carbon atoms.
Here too, the solidification values (pour and setting point) lie below
-10°C, preferably below -15°C, while the flash points lie above
100oC
and preferably above 160°C. In the temperature range of 0 to
5°C, the
esters used in the drilling mud have a Brookfield (RVT) viscosity of
not more than 55 mPa.s, preferably not more than 45 mPa.s.
Two subclasses can be defined.for the ester oils of the type in
question. In the first, the unsaturated C16_24-T~~'-~xYlic acid
radicals present in the ester are derived by not more than 35 % by
weight from olefin di- and poly-unsaturated acids, with preferably at
least about 60 % by weight of the acid radicals being olefin mono-
unsaturated. In the second embo~d.i,ment, the C16-24-~nxYlic acids
present in the ester mixture are derived, by more than 45 % by weight,
preferably by more than 55 % by meight, frcan olefin di- and/or poly-
unsaturated acids. It is desirable for the saturated carboxylic acids
with from 16 to 18 carbon atoms, which are present in the ester
mixture, to amount' to not more than about 20 % by weight and in
pa~icular not mare than about 10 % by weight. Preferably, saturated
carboxylic acid esters, however, have lower numbers of carbon atoms in
the acid radicals. The carboxylic acid radicals present can be of
vegetable and/or animal origin. ~ples of vegetable raw materials
are, for.example, palm oil, peanut oil, castor oil and in particular
rapeseed oil. The carboxylic acids of animal origin are in
particular the corresponding mixtures of fish oils, such as herring oil.
A further interesting class of ester oils which can be used as mixture
oa~ponents for the use according to the invention, are esters which are
fluid at roan temperature and have flash points above 80°C, fran C1_5-
monocarboxylic acids and mono- and/or polyfunctional alcohols, which
are preferably also fluid and punpable in the temperature range of 0 to
5°C. Particularly suitable are the corresponding esters of these lower
CA 02050935 2001-03-14
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- 13 -
carboxylic acids with monofunctional aloohols with at least 8 carbon
atoms and/or esters of these acids with di- to tetra-hydric alcohols
with preferably 2 to 6 carbon atone. Acetic acid in particular ie
suitable for practical reasons as the ester-forming acid-varponent of
this class. T'he specifications for the rheology and volatility and the
solidification values of the preferred esters in this sub-class
correspond to the values given above.
Suitable mixture o~Onents from this sub-class are, in particular,
esters fran monofunctional aloohols of natural and/or synthetic origin,
the chain length of which in the presence of predominantly alip~hatic-
unsaturated aloohols can be in the range of 8 to 15 carbon atoms, but
in the case of olefin mono- and poly-unsaturated alcohols, can also
consists of higher numbers of carbon atone, for example, up to,about 24
carbon atoms. Details can be found in the Applicant's co-pending
Application 2,047,697.
Suitable mixture vocnQonents are finally, however, the esters, as
described in the Applicant's co-pending Application 2,047,706, from
monocarboxylic acids of synthetic and/or natural origin
with from 6 to 1I carbon atoms and mono- and/or polyfunctional
aloohols, which are preferably also fluid and piutpable in the
te~erature range of 0 to 5 oC. 'Ib ooc~plete the invention disclosure,
reference is made here to this extent to the above co-pending
Application.
Suitable mixture ocnponents also for the teaching of the present
invention are finally at least~largely water-insoluble alcohols of a
marked oleophilic nature,-as described as the oil phase or at Least as
a constituent of the eon~inuous oil phase of such W/O-invert, emulsions
in the co-pending Canadian Application of the Applicant 2,051,624,
filed March 29, 1990. For the purposes of the invention disclosure
reference is expressly made to the details in this co-pending Application.
Multi-substance mixtures fall within the scope of the invention, which
together with the ethers defined according to the invention, can
vontain one or more of the mixture oatponents listed here individually.
CA 02050935 2001-03-14
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Essentially any mixtures can be used provided that they fulfil the
basic Theological requirements for invert drilling fluids of the type
referred to here. E'~tamples of~ such multi-ca~onent mixtures are
materials based on various types of ester oils or also substance
mixtures additionally containing mineral oil.
Farther mixture oamponents of the invert drillinct fluid
These may be any of the usual mixture oo~r~onents for conditioning and
for the practical use of invert drilling mulls, such as are currently
used when mineral oils provide the continuous oil phase. In addition
to the dispersed aqueous phase, in particular emulsifiers, weighting
agents, fluid-loss additives, viscosifiers and alkali reserves can be
considered.
In an important eqnbodiment of the invention, oleophilic basic amine
ocmpounds are used as additives together with the ester oils, these
amine compounds are described in detail in,the aforementioned co-
pending Application 2,009,689 of the Applicant. For details
reference should be made to the disclosure of this co-pending
Application, as described above.
If eater oils are used as mixture ocmponents in the scope of the
invention - in particular ester oils based on carboxylic acids with at
least 6 carbon atoms -, it can be advantageous not to etrploy
significant amounts of strongly hydrophilic inorganic or organic bases
in the oil-base fluid. Lime can be used effectively as an alkali
reserve, in which case it is advantageous to limit the maxinuun amount
of lime to be used to about 2 lb/bbl, and it may be preferred to work
with a drilling-mud lime content slightly belc7w this figure, e.g. frcm
about 1 to 1.8 lb/bbl (lime/drilling fluid). Other lmown alkali
reserves can be used in addition to, or in place of, the lire. The
less basic metal oxides, such as zinc oxide, should particularly. be
mentioned. Even when these "acid traps" are used, care should still be
taken to ensure that the amounts used are not too large, so as to
prevent undesired premature ageing of the drilling fluid, which is
associated with an~increase-in viscosity and therefore a deterioration
in-the Theological properties. The special features discussed here of
CA 02050935 2001-03-14
_ 15 _ 2050~~5
the use according to the invention prevent, or at least restrict, the
formation of undesirable amounts of highly active O/W-emulsifiers so
that good theological properties are maintained in practice for a
sufficient period of time even when there is thermal ageing.
The following also applies:
Invert_drilling muds of the type being considered usually contain,
together with the continuous oil phase, a finely dispersed aqueous
phase in amounts from about 5 to 45 % by weight and preferably fran
about 5 to 25 % by weight. A dispersed aqueous phase fran about 10 to
25 % by weight can be red as particularly useful.
The following theological data apply for the theology of the preferred
invert drilling mode according to the invention: plastic viscosity
(PV) from about 10 to 60 mPa.s, preferably fran about 15 to 40 mPa.s;
yield point (YP) in the range from about 5 to 40 1b/100 ft2, preferably
from about 10 to 25 lb/100-ft2 - each measured at 50°C. Further
details on the measurement of these,.parameters, the measuring methods
used and the rest of the conventional composition of the invert
drilling fluids described here, are given in the prior art as cited
above and, for exatrple, described in full in the "Manual of Drilling
Fluids Technology" of NIr-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 summary, to
ca~lete the irnrention disclosure the following can be said:
The emulsifiers that can be used in practice are systems suitable for
the formation of the required W/0-emulsions. In particular, selected
oleophilic fatty acid salts, e.g. those based on amidoamine vc~ounds,
can be considered. ~ples of these are described in the already
cited US-PS 4,374,737 and the literature cited therein. A particularly
suitable type of emulsifier is the product sold by NL-Bairoid Co. under
the trade-mark "EZ-mul".
Such emulsifiers are sold oonmercially as highly concentrated active-
substanoe preparations and can, for exaaQle, be used in amounts firm
about 2.5 to 5 % by weight, particularly in amounts from about 3 to 4 %
t ~, _
t: v~-:
CA 02050935 2001-03-14
-16 - ~05~935
by weight - based on the ester oil phase.
Hydrophobized lignite in particular is used in practice as the fluid-
loss additive and thus in particular to fozm a dense coating of a
largely liquid-ir~ern~eable film on the bore-hole walls. Suitable
amounts are, for.exa~ple, from about 15 to 20 lb/bbl or from about 5 to
7% by weight, based on the oil phase.
The viscosifier usually enployed in drilling fluids of the type in
question is a ration-modified finely particulate bentonite, which can
~be used particularly in amounts from about 8 to 10 lb/bbl or fran about
2 to 4% by, weight, based on the oil phase. Barite is the weighting
material generally used in relevant applications to establish the
necessary pressure ocmpensation, the amounts added being varied
according to the drilling conditions anticipated in each case. By
adding barite, it is, for exanple, possible to raise the specific
gravity of the drilling fluid to 2.5 and preferably to a value in
the range from about 1.3 to~l.6.
The dispersed aqueous phase in these invert drilling fluids is loaded
with soluble salts - calcium chloride and/or potassium chloride are
mainly used. Saturation, at roan temperature, of the aqueous phase
with the soluble salt is preferred.
The aforementioned emulsifiers, or emulsifier systems, optionally also
serve to improve the oil wettability of the inorganic weighting
materials. In addition to-the aminoamides already mentioned, further
examples are alkylbenzene sulfonates and imidazoline ca~pounds.
Additional information regarding the relevant Prior Art can be found in
the following published Patent Specifications: GB 2 158 437, EP 229 912
and DE ~32 47 123.
.i.-,~
CA 02050935 2001-03-14
17 _
F~canple 1
An invert-drilling fluid is prepared according to the following
formulation with an O/W-ratio of 90/10:
239 ml dialkylether n-C 8
6 g gel former (oc~mercial product Omnigel )
9 g W/O-emulsifier ("EZ-~ul NT of HI~ Baroid Co.)
20 g orgar~opd~ilic lignite ( Duratone~of HI~ Bamid Co. )
28 g water
12 g CaCl2 x 2 H20
4g l~
255 g barite
First of all, the plastic viscosity (PV), the.yield point (YP) and the
gel strength of the invert drilling fluid are measured after l0 seconds
and after l0 minutes by a visoosity,measurement at 50oC on the unaged
material.
The invert drilling fluid is then aged for 16 hours at 125°C in the
autoclave in the so-called "roller-oven", to test the effect of
temperature on the stability of the emulsion. The viscosity values are
then measured again at 50°C.
The following are the values dete~na~ined for the unaged and aged
material:
unaged material aged material
plastic viscosity (PV) 19 21
yield point (YP) 11 8
gel strengths (1b/100 ft2)
10'sec. 4 4
min. . 5 5
HTHP fluid-loss value after ageing 4 ml
~;,
CA 02050935 2001-03-14
.~ -- X050935
- 18 -
Exanple 2
An invert-drilling fluid is prepared with an O/W-ratio of 80/20
acvording to the following-formulation:
210 ml di.alkylether as in ale 1
6 g gel former (canmercial product ~~4~nigel")
13 g organophilic lignite (~~Duratone" of NL Baroid Co.)
48.2 g water
20 g CaCl2 x 2 H20
8 g W/4-an~lsifier ( "EZ-~ul Nr" of I~ Baroid Co. )
2 g lime
220 g barite
T'he following are the values determined for the unaged and aged
material:
unaged material aced material
plastic viscosity (PV) 26 25
yield point (YP) I6 9
gel strengths (1b/100 ft2)
sec. ~ 4
10 min . 9 6
. HTHP f laid-loss value of aged drilling f laid 1 ml
F~cam~les 3 ~Go 5
In the following exanples, invert drilling fluids are prepared each
with a O/W-ratio of 90/20 according to the following formulation:
230 ml ether (see the identification below in F~ples 3 to 5)
26 ml water
6 g gel fornsas ( oannercial product Geltone
12 g orc~ar~hilic lignite ( "Duratone" of Pff~ Baroid Co. )
2 g 1~
6 g ~w/p-emulsifier ("EZ-mul Nr" of NL Baroid Co.)
CA 02050935 2001-03-14
- -19 - 20509~~
346 g barite
9.2 g CaCl2 x 2 H2C?
The following ethers are used in each case as the oil phase:
Example 3: Ce-O-CB
Exanple 4: C10-O-C10
F~anple 5: di-isotridecylether
The viscosity values measured for the unaged and aged drilling fluid
are stBm~arized below. The ageing is measured once after 16 hours at
125oC and in a further test after 72 hours at 125oC.
Exanple 3
unaged aged ; - aged
material material material
16 hrs/ 72 hrs/
125oC 125°C
plastic visvosity (PV) 21 24 ~ 29
yield point (YP) 10 7 6
gel strengths (1b/100 ft2)
sec. 4 3 4
10 min. 6 5 6
~ple 4
The test batches of this exanple are in addition modified in the
following way: for the ageing over a period of 72 hours, a drilling
fluid of the given formulation is used to which had also been added 2 g
of a markedly oleophilic amine (Applicant's oomrercial product Araphen ~'
G2D ~. The following values were measured:
CA 02050935 2001-03-14
- 20 -
unaged aged a~
material material material
16 hrs/ 72 hrs/
125C 125C
plastic viscosity (PV) 34 39 36
yield point (YP) 9 22
16
gel strengths (1b/100 ft2)
sec. 6 10 7
10 min. 8 17 8
ale 5
age a~
material material material
is hrs/ 72 hrs/
125C 125C
plastic viscosity (PV) 63 64 63
yield point (YP) 18 17 16
gel strengths (1b/100
ft2)
10 sec. 8 6 6
10 min. 11 9 9
