BIODEGRADABLE ADDITIVE CONCENTRATE IMPROVING THE
LUBRICITY OF WATER-BASED MUDS, USE THEREOF AND WATERBASED
MUD FOR DRILLING
The present invention relates to a biodegradable concentrate improving the lubricity
of water-based muds whether during drilling or during formation fracturing.
The invention also relates to the use of this biodegradable concentrate in a waterbased
mud as additive among other functional additives suitable for the application
envisaged for said mud whether in drilling or in fracturing. Finally the additive-treated waterbased
mud obtained after adding all its components is particularly suitable for shallow
onshore drilling operations.
Certain sites, such as large civil engineering projects, use large quantities of fluids
containing additives improving their lubricant properties and/or resistance to friction which
aid the proper operation of the tools used with these fluids, in particular for machining,
piercing and/or drilling, where there are major problems with friction. However, these fluids
used in large quantities are released in the form of rocky spoil after use, which means that
they must not pose any danger to the environment. Often this rocky spoil must be retreated
after use. Therefore a major objective is to provide fluids that are completely biodegradable
and can be released into the environment. This applies in particular to drilling fluids and
muds, both offshore and onshore.
It is known that drilling is of prime importance in petroleum exploitation and that
drilling is becoming deeper and deeper. Drilling technology is constantly evolving, whether
onshore or offshore, especially deep offshore, but also, more recently, in horizontal or
deflected drilling, where, by successive inclinations of one or two degrees, the trajectory of
the well becomes curved, which makes it possible to reach horizontal deposits at least more
than a kilometre or even more than ten kilometres from the wellhead.
The frictional forces that are exerted are therefore becoming greater and greater,
hence the increased importance of the lubricant properties of the drilling fluid and of its
effect on resistance to friction at the level of the drilling tools.
As is well known, the drilling technique uses a drill bit fixed on the end of drillpipes,
which, when driven in rotation, bores the well by grinding the rocks.
As drilling progresses, drill bits of smaller and smaller diameter are used, and at
each step the well is consolidated with a steel tube called "casing", which is lowered inside
the hole, and then fixed with cement.
3
During drilling, a drilling fluid is circulated, with injection into the drill bit and
expulsion from the latter into the contact zone with the rock, and is then brought back up to
the top of the well through the annular space separating the drillpipes from the "casing".
This fluid generally performs the following main functions:
- cooling the drill bit,
- reducing the metal/metal frictional forces, between the casing and the drillpipes,
and metal/rock frictional forces, both at the level of the drill bit and in the annular zone,
since the fluid comes up laden with particles of ground rock, called "cuttings" in the art,
- discharging the rock debris to the exterior,
- creating a pressure on the walls of the hole, to prevent their collapse, and
- balancing the pressures between the bottom of the well and the surface, in order
to maintain control of the well and prevent a blowout.
In the case of deep-water offshore drilling, the water temperatures encountered,
close to 4 to 5°C, require good control of the viscosity of the drilling fluids at these low
temperatures.
Various types of drilling fluids or muds have been used in the past, such as waterbased
fluids, containing water and additives for adjusting their density and their rheological
properties, oil-based fluids, and emulsions of the water-in-oil type or inverted emulsions, of
the oil-in-water type, as described in particular in US 2,816,073.
In water-based muds (WBMs), the drilling fluid is water; the water-based muds are
generally reserved for applications that are not very technical and for very shallow onshore
or offshore drilling (a few metres).
As in the case of fluids containing a high proportion of water, various problems
arise such as excessive acidity or basicity of these muds, which can give rise to blocking of
the tools, adjustment of the density and viscosity but also problems of friction at the level of
the drilling tool and tool-rock contacts. This last-mentioned point raises the problem of the
lubricating capacity of a water-based mud and improvement of its lubricity with additives
called lubricity additives and/or anti-wear additives and/or also anti-friction additives.
Improvement of the lubricity of muds has been the subject of many works and
various ways of measuring the lubricity of these water-based muds have been envisaged.
In patent US2010/0305009, the inventors suggest the use of oligoglycerol esters in
water-based muds containing more than 70% by weight of water. More particularly, these
oligoglycerol esters contain from 20 to 45% by weight of glycerol, from 20 to 40% by weight
of diglycerol, from 10 to 20% by weight of triglycerol, from 1 to 10% by weight of
4
tetraglycerol and 0.5 to 5 % by weight of pentaglycerol in the form of esters of fatty acids
comprising from 2 to 18 carbon atoms, mono- and polyunsaturated, preferably of oleic,
linoleic and/or linolenic acid or of pine oil (tall oil) fatty acids.
In patent US3047493, in order to improve its lubricity, it is proposed to add to
water-based mud, from 0.3 to 7% by weight of an organic carboxylic compound, of the tall
oil type containing saturated, mono- and polyunsaturated fatty acids and resin acids, or also
triglycerides of fatty acids with 12 to 18 carbon atoms per chain. In order to improve the
miscibility of these products, it is proposed to add emulsifiers such as non-ionic surfactants,
clay (between 0.25 and 20% by weight in the mud), lignin or also sulphonate derivatives
such as calcium lignosulphonate or a calcium alkaryl sulphonate.
In patent US 4409108, a composition is proposed for reducing the resistance to
friction in an aqueous fluid between the moving part and the adjacent surface of a tool, said
composition comprising up to 5% by weight of the composition of an odour masking agent,
from 5 to 60% by weight of a 50/50 mixture of glycerol monooleate and glycerol dioleate
and from 10 to 90% by weight of an alcohol or mixture of alcohols with 7 to 10 carbon
atoms, these alcohols being essentially linear.
In patent US 6806235, a method is proposed that produces an improvement in the
lubricity of a water-based drilling fluid by adding, to said aqueous drilling fluid, a lubricating
compound comprising a partial glyceride derived from tall oil fatty acids. This partial
glyceride has a pour point preferably below 0°C. The aqueous drilling fluid comprises more
than 90% by weight of water, and from 1 to 3% by weight of partial glyceride. As this partial
glyceride is water-insoluble, an anionic surfactant from the group of sulphonates and
sulphates of linear fatty acids, optionally mixed in a ratio of surfactant to partial glyceride
varying from 1:10 to 1:20, is added.
For determining the lubricity of the various additives envisaged for a water-based
drilling mud in these patents, only the Falex method measuring shear strength in waterbased
muds containing all the components necessary for a given application is envisaged
in certain of these patents. In the context of the present invention, screening for compounds
having the ability to improve the lubricity of the water-based mud and therefore of water is
carried out independently of the constituents added to the mud subsequently. This
screening was carried out using the method of measurement known as the high-frequency
reciprocating rig (HFRR) method. This test makes it possible to evaluate the lubricity of the
compositions by reproducing the operating conditions of standard ISO 12156-1 for a test
duration fixed at 115 minutes, an aqueous matrix and a temperature corresponding to
ambient temperature (25°C).
5
One of the applicant's main objectives is to obtain an effectiveness of lubricity
greater than or equal to that of the commercially available additives while maintaining a
completely biodegradable character of these additives with respect to the environment into
which they might be released after use. Moreover, these additives must be water-miscible
without the addition of sulphate and sulphonate derivatives.
Another objective is to use additives that have a pour point measured according to
standard ASTM D97 that is well below that of water, i.e. below 0°C and even below –5°C.
A subject of the present invention is therefore a biodegradable additive concentrate
for water-based mud with a pour point according to standard ASTM D97 below -5°C
improving the lubricity of water-based muds, said concentrate being characterized in that it
comprises at least one compound selected from the group consisting of the diglycerol
mono- and diesters, the acids and the ester derivatives of monocarboxylic fatty acids
comprising from 16 to 22 carbon atoms per chain, the acids and the ester derivatives of
resin acids, the monoesters of polyol comprising more than 4 hydroxylated groups and of
carboxylic fatty acids comprising from 6 to 12 carbon atoms, saturated and unsaturated by
at least one unsaturation, and the mono- and polyalkoxylated esters of saturated and
unsaturated dicarboxylic acids comprising from 6 to 12 carbon atoms.
According to one embodiment, the biodegradable additive concentrate consists only
of at least one compound selected from the group consisting of the diglycerol mono- and
diesters, the acids and the ester derivatives of monocarboxylic fatty acids comprising from
16 to 22 carbon atoms per chain, the acids and the ester derivatives of resin acids, the
monoesters of polyol comprising more than 4 hydroxylated groups and of carboxylic fatty
acids comprising from 6 to 12 carbon atoms, saturated and unsaturated by at least one
unsaturation, and the mono- and polyalkoxylated esters of saturated and unsaturated
dicarboxylic acids comprising from 6 to 12 carbon atoms.
Advantageously, the active materials having an influence on the lubricity of waterbased
mud can be used alone or mixed with another active material with which, besides
dissolution of the least dispersible substance, a synergistic effect is also observed with
respect to the lubricity of the mud. Thus, the biodegradable additive concentrate can
comprise at least one compound selected from the group consisting of:
- the diglycerol mono- and diesters,
- the acids and the ester derivatives of monocarboxylic fatty acids comprising from
16 to 22 carbon atoms per chain, and
- the acids and the ester derivatives of resin acids, optionally mixed with at least
one compound selected from the group consisting of the monoesters of polyol comprising
6
more than 4 hydroxylated groups and carboxylic fatty acids comprising from 6 to 12 carbon
atoms, saturated and unsaturated with at least one unsaturation, and the mono- and
polyalkoxylated esters of saturated and unsaturated dicarboxylic acids comprising from 6 to
12 carbon atoms, or a mixture thereof.
According to one embodiment, the biodegradable additive concentrate consists of
at least one compound selected from the group consisting of:
- the diglycerol mono- and diesters,
- the acids and the ester derivatives of monocarboxylic fatty acids comprising from
16 to 22 carbon atoms per chain, and
- the acids and the ester derivatives of resin acids,
mixed with at least one compound selected from the group consisting of the monoesters of
polyol comprising more than 4 hydroxylated groups and carboxylic fatty acids comprising
from 6 to 12 carbon atoms, saturated and unsaturated with at least one unsaturation, and
the mono- and polyalkoxylated esters of saturated and unsaturated dicarboxylic acids
comprising from 6 to 12 carbon atoms, or a mixture thereof.
The monoesters of polyol comprising more than 4 hydroxylated groups and of
carboxylic fatty acids comprising from 6 to 12 carbon atoms, saturated and unsaturated by
at least one unsaturation, and the mono- and polyalkoxylated esters of saturated and
unsaturated dicarboxylic acids comprising from 6 to 12 carbon atoms have solvation
properties.
Thus, mixtures of fatty acids and/or resin acids with mixtures of diglycerol monoand
diesters or also with monoesters of polyols such as sorbitol or sorbitan allow both
dissolution in water and improvement of the lubricity of water for quantities of active
substances in the water less than those found in the prior art, in particular once the
concentration of said concentrate reaches 200 ppm by weight.
Thus, the additive concentrate will advantageously comprise mixtures of diglycerol
monoesters and diesters obtained from at least one saturated or polyunsaturated
monocarboxylic fatty acid ester comprising from 16 to 22 carbon atoms. Preferably, the
mixture will comprise a diglycerol monoester content varying from 30 to 60% by weight of
the mixture and a diglycerol diester content varying from 40 to 70% by weight of the
mixture, the ester group being obtained from at least one saturated or unsaturated linear
fatty acid ester comprising from 16 to 22 carbon atoms.
Preferably, the diglycerol monoester/diester mixture is obtained by
transesterification of fatty acid methyl ester by diglycerol. Thus, said diglycerol
7
monoester/diester mixture can comprise up to 20% by weight of diglycerol triester and less
than 8% of diglycerol tetraester.
In another embodiment of the invention, the concentrate can comprise up to 50%
by weight of active substance consisting of at least one acid or linear monocarboxylic fatty
acid ester derivative comprising from 16 to 22 carbon atoms optionally mixed with at least
one resin acid selected from the group of abietic acid and derivatives thereof.
As these compounds are not water-soluble, they are dissolved in water by adding
solvents or another active substance capable of dissolving them.
Thus, the concentrate according to the invention can comprise from 50 to 99% by
weight of at least one compound with solvation properties selected from the polyol
monoesters comprising from 5 to 10 hydroxylated groups and the carboxylic fatty acids
comprising from 6 to 12 carbon atoms, saturated and unsaturated by at least one
unsaturation or also from the polyethoxylated esters of linear dicarboxylic acids. An
example is the product NYCOBASE 618 mainly constituted by ethoxylated esters of
dicarboxylic acids.
In a first embodiment, the concentrate will comprise from 50 to 100% by weight of
the diglycerol mono- and diester mixture and from 0 to 50% of at least one acid or ester
derivative of linear monocarboxylic fatty acids comprising from 16 to 22 carbon atoms,
optionally mixed with at least one resin acid selected from the group of abietic acid and
ester derivatives thereof.
In a second embodiment, the concentrate can comprise 1 to 50% by weight of at
least one acid or ester derivative of linear monocarboxylic fatty acids comprising from 16 to
22 carbon atoms optionally mixed with at least one resin acid selected from the group of
abietic acid and ester derivatives thereof and from 50 to 99% by weight of at least one
compound with solvation properties selected from the monoesters of polyol comprising from
5 to 10 hydroxylated groups and of carboxylic fatty acids comprising from 6 to 12 carbon
atoms, saturated and unsaturated by at least one unsaturation, or else from the
polyethoxylated esters of linear dicarboxylic acids.
Among the polyol monoesters, sorbitan laurate is preferred, said ester optionally
being ethoxylated.
Preferably, the concentrate comprises a mixture of acids or of esters obtained from
a composition mainly constituted by a mixture of linear C16 to C22 monocarboxylic fatty
acids.
8
In particular, said preferred composition based on fatty acids is of natural origin,
i.e. within the meaning of the present invention of vegetable and/or animal origin and not of
fossil origin.
The compositions predominantly composed of C16-C22 monocarboxylic fatty
acids can be obtained for example by hydrolysis of natural and/or genetically modified
vegetable oils, or of animal fats; the fatty acids derived from peanut, palm, olive, rapeseed,
cotton, maize, sunflower, soya, flax, or tallow oils and/or derived from lard may be
mentioned.
Within the meaning of the present invention, by composition predominantly
constituted by C16 to C22 monocarboxylic fatty acid(s) is meant any composition in which
the concentration of C16 to C22 monocarboxylic fatty acid(s) represents from 60% to 100%
based on the total mass of the composition. In general, the rest of the composition
comprises monocarboxylic fatty acids the hydrocarbon chain of which has fewer than 16
carbon atoms and/or has more than 22 carbon atoms. The compositions predominantly
consisting of C16 to C22 monocarboxylic fatty acid(s) optionally comprise resin acids. The
concentration of resin acids preferably represents up to 40% by mass of the acids (fatty
acids + resin acids) and advantageously less than 5% of the total mass of the acids (fatty
acids + resin acids).
Among the resin acids, the abietic, dihydroabietic, tetrahydroabietic,
dehydroabietic, neoabietic, pimaric, laevopimaric, parastrinic acids may be mentioned, nonlimitatively.
The compositions predominantly composed of C16 to C22 monocarboxylic fatty
acid(s) and containing resin acids can be obtained by distillation of tall oil, a by-product from
the manufacture of the wood pulp; the term tall oil fatty acids (TOFAs) is then used. TOFAs
are marketed for example by the company TOTAL ADDITIFS & CARBURANTS SPECIAUX
under the trade-names PC 30, PC 31 and PC 32. In these commercial mixtures, the resin
acids generally represent less than 10% by mass and advantageously less than 5% of the
total weight of the acids (fatty acids + resin acids).
The esters of these acids within the meaning of the present invention are preferably
esters of glycerol and of TOFA.
A second subject of the invention is the use of the additive concentrate in a waterbased
mud up to a content of 10,000 ppm by weight relative to the water in order to improve
the lubricity of the mud at the level of the tool during drilling.
This use consists of adding preferably 200 to 5000 ppm by weight of additive
concentrate according to the invention to the water of the mud.
9
A third subject of the invention is the water-based mud comprising from 200 to 5000
ppm of an additive concentrate as described above in the presence of compounds capable
of adjusting the pH and density of the mud envisaged, in particular in combination with
functional additives depending on the type of application of the mud.
In the remainder of the present description, examples are given for purposes of
illustration of the present invention and are not in any way intended to limit its scope.
Example 1
The present example aims to describe the various additive concentrates according
to the invention and the water-based muds that it is possible to prepare from them.
The additive concentrates will be referenced Ci and the muds according to the
invention Bi: they are presented in the following Tables I and II, respectively.
The water-based muds prepared from the additive concentrates in Table I are
shown in Table II. For each of the muds, the wear diameter was measured by an HFRR
method derived from ISO 12156-1. This wear diameter is supplemented with a
measurement of coefficient of friction.
It can be seen from Table II that the use of the additive concentrate makes it
possible to reduce the coefficient of friction. In fact, the coefficient of friction obtained for
the additives according to the invention is always less than 0.419, which is the reference
value for mud B0. When the additive concentrate in the water reaches 500 ppm by weight,
the lubricity of the fluid is improved significantly, which is reflected in a reduction in the
wear diameter and coefficient of friction.
Example 2
This example aims to compare the performance of the water-based muds
according to the invention in terms of improvement of the lubricity of these muds by HFRR
measurement and determination of the coefficient of friction relative to the performance of
a commercially available "Radiagreen EME salt" additive. The results are presented in
Table IIIThe wear results obtained with the additive concentrates according to the
invention demonstrate performance similar to the commercial additives starting from
500 ppm by weight.

CLAIMS
1. Biodegradable additive concentrate with a pour point according to standard ASTM
D97 below -5°C, which improves the lubricity of water-based muds, characterized in
that it comprises at least one compound selected from the group consisting of:
- the diglycerol mono- and diesters,
- the acids and the ester derivatives of monocarboxylic fatty acids comprising 16 to
22 carbon atoms per chain,
- the acids and the ester derivatives of resin acids,
- the monoesters of polyol comprising more than 4 hydroxylated groups and of
carboxylic fatty acids comprising from 6 to 12 carbon atoms, saturated and
unsaturated by at least one unsaturation, and
- the mono- and polyalkoxylated esters of saturated and unsaturated dicarboxylic
acids comprising from 6 to 12 carbon atoms.
2. Concentrate according to claim 1, characterized in that it comprises at least one
compound selected from the group consisting of:
- the diglycerol mono- and diesters,
- the acids and the ester derivatives of monocarboxylic fatty acids comprising from
16 to 22 carbon atoms per chain, and
- the acids and the ester derivatives of resin acids,
optionally mixed with at least one compound with solvation properties selected from
the group consisting of the monoesters of polyol comprising more than 4
hydroxylated groups and of carboxylic fatty acids comprising from 6 to 12 carbon
atoms, saturated and unsaturated by at least one unsaturation, and the mono- and
polyalkoxylated esters of saturated and unsaturated dicarboxylic acids comprising
from 6 to 12 carbon atoms, or a mixture thereof.
3. Concentrate according to claim 1 or 2, in which the diglycerol monoesters and
diesters are added together to said concentrate, the diglycerol monoester content
varying from 30 to 60% by weight of the mixture and the diglycerol diester content
varying from 40 to 70% by weight of the mixture, the ester group being obtained
from at least one saturated and/or unsaturated linear fatty acid comprising from 16
to 22 carbon atoms.
15
4. Biodegradable concentrate according to one of claims 1 to 3 comprising up to 50%
by weight of at least one acid or ester derivative of linear monocarboxylic fatty acids
comprising from 16 to 22 carbon atoms optionally mixed with at least one resin acid
selected from the group of abietic acid and derivatives thereof.
5. Concentrate according to one of claims 1 to 4 comprising from 50 to 99% by weight
of at least one compound with solvation properties selected from the monoesters of
polyol comprising from 5 to 10 hydroxylated groups and of carboxylic fatty acids
comprising from 6 to 12 carbon atoms, saturated and unsaturated by at least one
unsaturation, or also from the polyethoxylated esters of linear dicarboxylated acids.
6. Concentrate according to any one of the preceding claims, characterized in that it
comprises from 50 to 100% by weight of the diglycerol mono- and diester mixture
and from 0 to 50% of at least one acid or linear monocarboxylic fatty acid ester
derivative comprising from 16 to 22 carbon atoms, optionally mixed with at least
one resin acid selected from the group of abietic acid and ester derivatives thereof.
7. Concentrate according to any one of the preceding claims, characterized in that it
comprises from 1 to 50% by weight of at least one acid or linear monocarboxylic
fatty acid ester derivative comprising from 16 to 22 carbon atoms optionally mixed
with at least one resin acid and/or an ester derivative of said acid selected from the
group of abietic acid and derivatives thereof, and from 50 to 99% by weight of at
least one compound with solvation properties selected from the monoesters of
polyol comprising from 5 to 10 hydroxylated groups and of carboxylic fatty acids
comprising from 6 to 12 carbon atoms, saturated and unsaturated by at least one
unsaturation, or also from the polyethoxylated esters of linear dicarboxylated acids.
8. Concentrate according to claim 7, characterized in that the compound with solvation
properties is sorbitan laurate.
9. Concentrate according to one of the preceding claims, characterized in that it
comprises a mixture of acids or of esters obtained from a composition mainly
constituted by a mixture of linear C16 to C22 monocarboxylic fatty acids, optionally
mixed with at least one resin acid.
16
10. Concentrate according to claim 9, characterized in that the composition mainly
constituted by a mixture of fatty acids is of natural origin, i.e. of vegetable and/or
animal origin.
11. Concentrate according to claims 9 and 10, characterized in that the composition
mainly constituted by a mixture of fatty acids comprises up to 40% by weight of the
composition of resin acids and preferably less than 5% by weight of resin acids.
12. Use of the additive concentrate according to one of claims 1 to 11 in a water-based
mud comprising up to a content of 10,000 ppm by weight of said additive
concentrate in the water in order to improve the lubricity of said water-based mud.
13. Use according to claim 12, characterized in that the additive concentrate content
varies from 200 to 5000 ppm by weight relative to the water of said mud.
14. Water-based mud comprising 200 to 5000 ppm by weight of additive concentrate
according to one of claims 1 to 10 in the presence of compounds capable of
adjusting the pH and density of the mud envisaged, in particular in combination with
functional additives suitable for the type of application of the mud.