DK170979B1 - Use of esteries in drilling fluids - Google Patents

Description

DK 170979 B2 l

BACKGROUND OF THE INVENTION The present invention relates to novel drilling flushing fluids based on esteryls and their invert drilling flushing sludge, which is characterized by high ecological acceptability, together with good condition and use characteristics. An important area of application of the novel drill rinsing systems is off-shore drilling for the utilization of petroleum and / or natural gas deposits, the invention being particularly aimed at providing technically usable drilling rinses with high ecological acceptability.

The use of the novel drill rinsing systems is of particular importance in the marine field, but is not limited thereto. The novel flushing systems can generally be used also for land-based wells, for example for geothermal wells, for water wells, for conducting geoscientific wells and for drilling in the field of mining. In principle, it also applies here that the ecotoxic problem area is substantially simplified by means of the ester-based drilling oil fluids selected according to the invention.

As is known, liquid rinsing systems for lowering rock bores during application of the loosened drilling materials are limited to thickened flowable water or oil based systems. In practice, these latter oil-based systems are gaining importance, especially in the area of off-shore wells or for the breakthrough of water-sensitive layers.

20

Oil-based drilling fluids are generally used as so-called invert emulsion sludges, which consist of a three-phase system: oil, water and finely divided solids. These are preparations of the type water / oil emulsions, ie. that the aqueous phase is distributed heterogeneously finely dispersed in the closed oil phase. Several stabilizers can be used to stabilize the overall system and to adjust the desired usage properties, especially emulsifiers or emulsifier systems, gravitational agents, fluid loss additives, alkali reserves, viscosity regulators and the like. For details, for example, reference is made to that of P. A. Boyd et al. published article "New Base Oil Used in Low-Toxi-City Oil Muds", Journal of Petroleum Technology, 1985, pages 137 to 142, as well as R.B.

30 Bennet, "New Drilling Fluid Technology - Mineral Oil Mud", Journal of Petroleum Technology, 1984, pages 975 to 981, as well as the literature cited therein.

DK 170979 B2 Η Η

Initially, oil-based drilling fluids were built up of diesel fuel fractions containing aromatic substances. To detoxify and mitigate the resulting ecological problem, it has then been proposed to use the largely aromat-free hydrocarbon fractions - nowadays also referred to as "nonpolluting oils" 5 - as closed oil phase, referring here to the literature cited above. . Although some progress has been achieved in this way in the exclusion of the aromatic compounds, a further reduction of the environmental problem - triggered by drilling fluids of the kind in question - seems imperative. This is particularly valid in the downturn of offshore wells for the exploitation of petroleum or natural gas deposits because the marine ecosystem responds particularly sensitively to the discharge of toxic and readily degradable substances.

The technology in question has for some time recognized the importance of ester base oil phases in solving this problem. Thus, U.S. Pat.

15 4,374,737 and 4,481,121 oil-based drilling rinses in which non-polluting oils must be used. As non-polluting oils are mentioned next to each other and as equivalent aromatic free mineral oil fractions and plant oils of the type peanut oil, soybean oil, flaxseed oil, corn oil, rice oil or oils of animal origin, such as whale oil. Everywhere, with respect to the esteries of vegetable and animal origin mentioned here, triglycerides of natural fatty acids are known, which are known to have a high environmental compatibility and in relation to hydrocarbon fractions - even when they are aromatic free - have a clear superiority from ecological considerations.

J

Interestingly, however, no example in the aforementioned U.S. Patents discloses the use of such natural esters in invertebrate fluids of the kind in question. Mineral oil fractions are used everywhere as a closed oil phase.

The studies underpinning the invention have shown that for practical reasons the use of readily degradable oils of vegetable and / or animal origin contemplated by the prior art cannot be considered. The rheological properties of such oil phases cannot be obtained for the broadly demanding temperature range from first 0 to 5 ° C and secondly to 1250 ° C and above.

3 DK 170979 B2 In U.S. Patent No. 4,481,121, in its general description portion, as a useful oil phase, in addition to the triglycerides, a commercial product "Arizona 208" from the Arizona Chemical Company, Wayne, NJ, discloses a purified isooctyl moiety. -no alcohol esters of very pure tall oil fatty acids. An ester of a monofunctional alcohol and monofunctional carboxylic acids mentioned herein is indicated as equivalent to natural origin triglycerides and / or aromatically free hydrocarbon fractions.

10 In the aforementioned US patent, there are no similar examples of the use of such an ester of monofunctional components.

The teachings of the invention described below are based on the recognition that it is in fact possible to produce oil-based invert flushing fluids of the present invention on the basis of high environmental acceptability ester, as in terms of their storage and application behavior corresponds to the best known oil-based invert - rinse systems, yet it has the additional benefit of increased environmental acceptability. Two important acknowledgments master the teachings of the invention:

20 I

For the construction of mineral oil-free oil-based invert rinse fluids, the triglycerides present in the form of natural oils are not suitable, but useful are the esters derived from these oils or fats from the monofunctional carboxylic acids with monofunctional alcohols. The other significant recognition is that, in use, the ester species of the present invention do not in fact behave like the previously used hydrocarbon mineral oil fractions used so far. The esters of the monofunctional components of this invention undergo a partial hydrolysis in the practical application. Thereby free fatty acids are formed. These then react with the alkaline constituents present in drilling rinsing systems of the kind in question - e.g. with it to! 30 corrosion protection used alkali reserve - to form the corresponding salts. Salts of highly hydrophilic bases and the acids present in the fats or oils of natural origin, with a chain length of up to approx. C24 - and especially the long-chain acids of approx. However, C6 to C22 * are, as is well known, compounds with relatively high HLB values which lead in particular to the adjustment and stabilization of oil / water emulsions. As is well known, the washing and cleaning technique uses it to a large extent.

The formation of undesirably large amounts of such oil / water emulsifier systems, however, will generate the water-oil emulsions required for the purpose of the invention and thus lead to disruption. The teachings of the invention hereinafter describe how the practically useful ester-based invertebrate flushing fluids can be used despite these system-independent difficulties.

Accordingly, the present invention relates, in a first embodiment, to the use of selected in the temperature range of 0 to 5 ° C flow and pumpable esters of mono-functional alcohols of 2 to 12, in particular 4 to 12 carbon atoms and aliphatic saturated carboxylic acids of 12 to 16 carbon atoms. or mixtures thereof with not more than approx. the same 15 amounts of others as the oil phase or at least a substantial portion of the inert vert rinsing sludge oil phase, which in a closed oil phase contains a dispersion aqueous phase together with an alkali reserve, emulsifiers, gravitational agents, fluid release additives and if desired, additional usual additives.

In a further embodiment, the invention relates to mineral oil-free invert drilling fluids suitable for off-shore utilization of petroleum or natural gas deposits and containing a dispersed aqueous phase of ester oils containing a dispersed aqueous phase together with an alkali reserve, emulsifiers, thickeners. , gravitational agents, fluid-loss additives and, if desired, additional usual additives, the characteristics of the invention being that the oil phase is formed, at least for the most part, by esters of monofunctional alcohols having 2 to 12 carbon atoms and aliphatic saturated monocarboxylic acids having 12 to 16 carbon atoms. According to a preferred element of the invention, these closed oil phase esters in the temperature range of 0 to 5 ° C exhibit a Brookfield (RVT) viscosity of not more than 50 mPas.

H

In the two embodiments of the invention disclosed herein, in a particularly preferred embodiment, ester is used which, at least predominantly in proportion, that is, for at least 50 to 51%, goes back to aliphatic C -monocarboxylic acids, such esters may be particularly suitable which, for at least 60% by weight - calculated in relation to the present carboxylic acid mixture - are esters of such aliphatic C 1-4 monocarboxylic acids.

In one important embodiment, only the saturated aliphatic monocarboxylic acid saturated acid is present in said wider range of C12-16, but particularly the range of C12-H · invention is not limited thereto. However, the use of esters of other carboxylic acids for a maximum of approx. the same amount and preferably in minor amounts may be advantageous. In particular, short-chain aliphatic monocarboxylic acids or their esters and / or esters of longer-chain carboxylic acids are considered here. In this latter case of the use of esters of longer chain carboxylic acids, 15 is, however, preferable to the least proportionate use of corresponding one and / or several times olefinically unsaturated long chain carboxylic acid derivatives. Considering, in this embodiment, as blending components, first and foremost, one and / or several times olefinically unsaturated monocarboxylic acid esters come in the range of C | 6.24, especially C-i8_22.

According to a further important and hereinafter elaborately preferred element of the invention, the use of the ester defined herein is waived for the use of substantial amounts of highly hydrophilic bases, such as alkali hydroxide and / or diethanolamine, in the finished invertebrate liquid.

25 Inverted drilling fluid with a closed oil phase according to the prior art, as is well known, always contains an alkali reserve, especially for protection against penetration of CO 2 and / or H2 S in the drilling rinse fluid and thus for protection against corrosion of the metal parts of the drill rod system. A useful alkaline reserve is within the framework of the actions performed according to the invention the addition of lime (calcium hydroxide or lime) or the use of weaker basic metal oxides, for example of the zinc oxide type and / or other zinc compounds. Details of these elements in the teachings of the invention I DK 170979 B2 Η I 6 Η are given in more detail below. To begin with, I will disclose the esterols selected according to the invention, which determinate exclusively I, or at least predominantly, the closed oil phase of the invert drill mud.

The esteryls of the monofunctional alcohols used in the invention and selected monocarboxylic acids may be derived from unbranched or branched hydrocarbon chains.

In the Esters of suitable straight-chain acids are of particular importance. Saturated monocarboxylic acids in the range C12-i6 and especially in the area Ct2-i4 can form esteryls with monofunctional alcohols having the number of carbon atoms defined by the invention, which exhibit the necessary rheological properties even down to temperatures in the range from 0 to 5 ° C and are particularly flow and pumpable in this temperature range. Preferred drilling mud oil phase esters for the purposes of the invention are saturated components having a Brookfield (RTV) - in viscosity range of not more than 50 mPas and preferably not more than 40 mPas in the temperature range of 0 to 5 ° C. By selecting suitable components for the ester formation, it is possible to adjust the viscosity of said I temperature range from 0 to 5 ° C to values not exceeding 30 mPas *, for example in the range of I 10 to 20 mPas. It is obvious that important benefits are obtained here for the work in the marine area, since very low temperatures in the surrounding water can be predicted.

I 20 I

In the preferred ester used on the basis of selected individual components or on the basis of ester mixtures, in the preferred embodiment, solidification values (flow point and set point) are below -10 ° C and especially below -15 ° C. In spite of this high mobility at low temperatures, the molecular size of the ester prescribed by the invention I25 ensures that its flash point has sufficiently high values. They are at least 80 ° C, but generally exceed the temperature limit of approx. 100 ° C. Ester oils are preferred which have flash points above 150 to 160 ° C.

In that esteries of the aforementioned kind can be produced whose flash points are at 185 ° C

In or higher.

I H

In a further important embodiment, the ester oils in the range of the saturated C12-C6 monocarboxylic acids required by the invention go back to materials of predominantly vegetable origin. For example, carboxylic acids or carboxylic acid mixtures having a predominant content of saturated monocarboxylic acids in the indicated range can be recovered from post-growing triglycerides such as coconut oil, palm kernel oil and / or babassu oil. Generally, fatty acid mixtures of this origin contain a limited amount of lower fatty acids (C6.io), which is generally a maximum of 15%. By and large, their content of C12 / 14 acids, which usually constitute at least 50%, is usually 60% or more of the carboxylic acid mixture. The residual minor residue falls on higher fatty acids, whereby unsaturated components in this region play a significant role. Thus, carboxylic acid mixtures of this nature already easily lead to materials with satisfactory rheological properties due to their naturally predicted structures.

As an embodiment of the invention, in particular, monofunctional ester ions are considered as blending components of the invention, such as those disclosed in the parallel patent application No. 1175 / 91.1 in view of the teachings of the present invention, these blending components are admittedly preferably used in subordinate amounts (maximum 49%, calculated in relation to the ester-20 oil mixture). In order to complete the description of the invention, this class of the possible blending components is briefly mentioned. Higher details appear in the said parallel application.

With respect to these possible mixing components, these are esters of monofunctional alcohols of 2 to 12 carbon atoms and olefinically mono- and / or polyunsaturated monocarboxylic acids of 12 to 24 carbon atoms. Here, too, the carboxylic acids can be derived from unbranched or branched hydrocarbon chains, again the straight-chain acids being of particular importance. Esters of the present higher chain lengths are flowable and pumpable down to temperatures ranging from 0 to 5 ° C when a sufficient degree of olefinically unsaturated ester constituents is ensured. Accordingly, in the preferred embodiment, esters of this kind are used as blend components which are derived from olefinically unsaturated carboxylic acids in the C16-24 range for more than DK 170979 B2 Η 70% and preferably for more than 80% by weight. Important natural starting materials provide carboxylic acid mixtures which, for at least 90% by weight, contain olefinically unsaturated carboxylic acids in the C range mentioned herein. The unsaturated carboxylic acids can hereby be single and / or several times olefinically unsaturated. Using carboxylic acids or carboxylic acid mixtures of natural origin, in addition to a single ethylenic double bond in the molecule, in particular the double and, to a minor extent, an additional triple ethylenic double bond per carboxylic acid molecule has a certain role.

Preferably, these esters of esters of unsaturated monocarboxylic acids with higher C chain numbers have by themselves solidification values (flow point and stiffness point) below -10 ° C and especially below -15 ° C. Due to their molecular size, the flash points for these mixture components also lie in the desired range, ie. at least above 80 ° C, preferably above 100 ° C and especially above 160 ° C. Mixture components of this kind in the preferred embodiment in the temperature range of 0 to 5 ° C should not exhibit Brookfield (RVT) viscosities above 55 mPas and preferably values not exceeding 45 mPas.

20 Within the context of these highly unsaturated blend components, two subclasses are of particular importance.

The first of these subclasses is based on unsaturated C₂-monocarboxylic acids which do not exceed about 35% by weight are two and possibly several times olefinically 25 unsaturated. Thus, the content of several times unsaturated carboxylic acid residues in the ester oil is relatively limited. Preferably, it is within the scope of this subclass that the carboxylic acid residues for at least about 60% by weight are monoolefinically unsaturated.

By way of derogation from this first subclass, the second substantially lower class is derived from the esteries herein referred to as blending components of such C 1-6 mo-nocarboxylic acid mixtures which, for more than 45% by weight, and preferably for more than 55% by weight can be derived from two and / or several times olefinically unsaturated acids within said C number range.

5 The most important ethylenically monounsaturated carboxylic acids in this field are the hexadecenoic acid (palmitoleic acid, C16), the oleic acid (C] 8), the related castoric acid (C | 8) and the erucic acid (C22) · The most important twice unsaturated carboxylic acid within the area under consideration is the linoleic acid (C18) and the most important three times ethylenically unsaturated carboxylic acid is the linolenic acid (C) 8).

10

As blending components, selected examples of the unsaturated monocarboxylic acid / monoalcohol ester type can be used. An example of this is possibly the esters of the oleic acid, possibly of the oleic acid obutyl ester type. For reasons of system rheology and / or for accessibility reasons, it is frequently desirable to use acid mixtures.

15

Plant oils of natural origin which, by their saponification or transesterification, lead to mixtures of carboxylic acids or carboxylic esters belonging to the first subclass mentioned above are, for example, palm oil, peanut oil, castor oil and especially rapeseed oil. In consideration, both rapeseed oil varieties with high erucic acid content and the 20 more modern rapeseed oil yields with reduced erucic acid content and therefore increased oleic acid content.

Carboxylic acid mixtures belonging to the second subclass mentioned above are widely available in the context of natural fats of vegetable and / or animal origin. Classical examples of high carboxylic acid oils in the range of Cie-i8 or C) 6_22 and at least 45% of at least twice the ethylenically unsaturated carboxylic acids are the cotton seed oil, soybean oil, sunflower oil and linseed oil. The tall oil fatty acids isolated during cellulose extraction also fall within this range.

A typical animal material for use in the extraction of appropriate carboxylic acid mixture; 30 things are fish oil, especially herring oil.

! DK 170979 B2 Η

In selecting the saturated esters used within the scope of the present invention, and especially also the latter ester oil mixtures, it should be taken into account that saturated carboxylic acid esters in the range C) 6 and higher C numbers may have relatively high melting points and thus easily presents rheological difficulties. Accordingly, according to the invention, it may be preferable that saturated carboxylic acid residues be present in the range of Cl6y, 8 and higher C-numbers in an amount of not more than about 10%.

20% by weight and in particular not more than approx. 10% by weight.

In contrast, the presence of saturated carboxylic acid residues in the C-number range 10 is below Cu · Here, on the other hand, valuable mixing components may be present for the ester oil phases of the invention. Their esters are, under practical conditions of use, as little oxidation-prone as the saturated major components envisaged by the invention in the range of especially C The rheological properties of the lower fatty acid esters favor the object of the invention to replace the hitherto only pure hydrocarbon oils used so far in practice, at least in part, but preferably predominantly or even completely with ester ions or ester ions.

According to the teachings of the invention, the alcoholic residues of the esters or esterbi breaths are preferably derived from straight-chain and / or branched-chain saturated alcohols, alcohols having at least 4 carbon atoms and, in particular, alcohols in the range up to approx. Cio is of particular importance. The alcohols may also be of natural origin and have usually been recovered by the corresponding carboxylic acids or their esters by hydrogenating reduction.

However, the invention is by no means limited to the use of materials of natural origin. For the monoalcohols as well as for the monocarboxylic acids, similar components of synthetic origin may be used instead of the use of natural origin materials. Typical examples of alcohols are the corresponding oxoalcohols (branched) or the linear alcohols recovered by the 30 Ziegler method. Also, especially monocarboxylic acid components present in carboxylic acid mixtures may be derived from the petrochemical

II

DK 170979 B2 synthesis. However, the advantages of the materials of natural origin used primarily consist of the demonstrated lower toxicological values, the ease of degradability and the availability. For the eventually desired destruction of the used oil rinse liquid by natural route, it is important that esteries of the kind described herein be degraded by both aerobic and anaerobic routes.

However, an important further point of view should be taken into account when using such esteries as the sole or predominant component of the invert oil sludge of the kind in question. Here, it is a matter of the difficulty already mentioned that the carboxylic esters are in principle hydrolysis-prone and, consequently, have to behave differently from the previously used pure hydrolysis-resistant hydrocarbon oils.

Invert drill rinsing muds of this type usually together with the closed oil phase contain the finely dispersed aqueous phase in amounts of 5 to 45% by weight and preferably in amounts of 5 to 25% by weight. The area from. 10 to 25% by weight of dispersion aqueous phase may be of particular importance. This condition, based on the constitution of conventional drilling flushing fluids, also applies to the invert flushing fluids herein.

It is obvious that there may, during continuous practical operation, disturb the equilibrium of the multiphase system, which is conditioned by some ester saponification.

20

The situation is made more difficult by the fact that in practice drilling fluids of the kind in question always contain an alkali reserve. An important importance is this alkali reserve as corrosion protection against unexpected penetration of acidic gases, namely especially CO 2 / or H2 S. The corrosion problem for the drill rod system requires safe adjustment of pH-25 values at least in the weak alkaline range, for example to pH 8.5 to 9. and higher values.

In purely hydrocarbon oil rinse fluids such as the oil phase, in practice, in general without concern, highly alkaline and therefore highly hydrophilic additives of an inorganic or organic nature are used, and in particular the particularly important in the sense that diethanolamine and / or triethanolamine are particularly common additives for the capture of H2S contaminants. In addition to and / or in place of the highly hydrophilic inorganic or organic bases mentioned herein, lime (calcium hydroxide or clay lime) or weaker basic metal oxides, especially the zinc oxide and other zinc compounds in 5, have considerable significance as an alkali reserve. Precious lime is widely used as an inexpensive alkalizing agent. Relatively large quantities are used, which are, for example, 5 to 10 lb / bbl (lime / oil rinse liquid) or even to even higher value. I 10 The use of ester rinse liquids of the kind described herein requires, in the variables discussed herein, a departure from past practice. Of course, here again, it must be ensured that the pH of the drilling flush liquid is kept at least in the slightly alkaline region and that a sufficient amount of alkali reserve is available for unexpected entanglements of especially acidic gases. However, this ensures that the post-hydrolysis I 15 is not adversely promoted and / or accelerated due to such an alkali content.

Thus, in the preferred embodiment of the actions of the invention I, it is appropriate not to consume substantial amounts of highly hydrophilic bases of inorganic and / or I or organic species in the oil rinse liquid. In particular, the invention dispenses with the use of alkaline hydroxides or highly hydrophilic amines of the diethanolamine and / or triethanolamine species. Lime can be used as an alkaline reserve with good effect. However, it is appropriate to limit the amount of lime to be maximally added to 5.71 g / l (2 lb / bbl), whereby it may be preferable to work with drilling mud fillings of lime slightly below , for example, in the range of 2.86 to 5.14 g / l (1 to 1.8 lb / l in 25 bbl) (lime / drill rinse fluid). In addition to or in place of the lime, other alkaline reserves I of a known kind can be used. Mention should be made here of the less basic metal oxides of the zinc oxide species. However, even with the use of such acid scavengers, care should be taken not to use excessive amounts to prevent an undesirable premature aging of the rinsing fluid - associated with an increase in viscosity and thus deterioration of the rheological properties. By means of the detail discussed herein in the embodiment of the invention, the formation of, or at least, the formation of undesirable amounts of highly effective oil / water emulsifiers is prevented so much that the good rheological application values also in the thermal aging during operation is maintained for a sufficient period of time. Here, in view of the prior art recommendations in the field of theoretical considerations, there is a decisive surplus, which, on the whole, first provides the practical utilization of the low toxic properties of the esters in question.

The according to the invention defined in the temperature range of 0 to 5 ° C flow and pumpable esters on the basis of the saturated monocarboxylic acids of 12 to 16 carbon atoms generally constitute at least approximately the closed oil phase of the drilling mud. Preferred, however, are such oil phases which contain esters of the species of the invention for the most part and in a particularly important embodiment of the invention practically consist of such esters. As mixing components for admixture with the ester defined in the invention, the compounds described in the parallel patent application No. 1175/91 are suitable. The invention also encompasses mixtures with such selected other esters.

The following rheological data apply to the rheology of preferred inverted drilling fluid in the invention: plastic viscosity (PV) in the range of 10 to 60 mPas, preferably 15 to 40 mPas, flow limit (Yield Point YP) in the range of 2.5 to 20 Pa (5 to 40 lb / 100 ft 2), viscosity preferably from 5 to 12.5 Pa (10 to 25 lb / 100 ft 2) - each time determined at 50 ° C. For the determination of these parameters, for the measurement methods used for this purpose, and for the otherwise usual composition of the inverted drilling oil rinse fluids described herein, the particulars according to the state of the art 25, which have already been discussed and carried out, are described in detail in the manual for example "Manual". Of Drilling Fluids Technology "by one applicant, BAROID DRILLING FLUIDS, INC., In particular, the" Mud Testing - Tools and Techniques "chapter, which is freely available to the interested professional. In summary, for purposes of completing the disclosure of the invention, the following may be said: 30 I DK 170979 B2 Η i 14 Η I The practically useful emulsifiers are systems which are suitable for forming the required water / oil emulsions. Particular consideration is given to selected oleophilic fatty acid salts, such as those based on amidoamine compounds. Examples thereof are described in U.S. Patent No. 4,374,737, and in the literature cited therein. A particular type of emulsifier suitable for 5 is the product sold by the applicant BAROID DRILLING FLUIDS, INC. Under the trade name "EZ-mul". Emulsifiers of this kind are sold commercially as highly concentrated active ingredient preparations and can be used, for example, in quantities of approx. 2.5 to 5% by weight, especially in amounts of approx. 3 to 4 wt% - calculated in relation to the ester phase.

I 10 I

I As a fluid-loss additive and, in particular, to form a dense coating of the drilling walls I with a largely liquid impervious film, in practice organophilic lignite is used in practice. Suitable amounts are, for example, in the range of 42.83 to 57.10 g / l (15 to 20 lb / bbl) or in the range of 5 to 7% by weight - based on the ester oil phase.

I I

II drilling flushing fluids of this kind, the commonly used viscosity forms a cationically modified organophile, finely divided bentonite, which can be used in particular in amounts of 22.84 to 28.55 g / l (8 to 10 lb / bbl) or in the range of 2 to 4% by weight, calculated from the ester phase. The gravity usually used in the practice in question for adjusting the required pressure equalization is barite, whose additions are adjusted to the expected conditions of the bore. For example, by the addition of barite, it is possible to increase the specific weight of the drilling rinse fluid to values in the range up to 2.5, and preferably in the range of 1.3 to 1.6.

I The disperse aqueous phase is filled with soluble salts in inverted drilling fluid of the type I in question. Mostly, calcium chloride and / or potassium I chloride are used, whereby the saturation of the aqueous phase at room temperature with the soluble I salt is preferred.

The aforementioned emulsifiers or emulsifier systems may also serve to improve the oil wettability of the inorganic gravity materials. In addition to the aminoamides mentioned previously, alkylbenzenesulfonates as well as imidazoline compounds are mentioned as further examples. Further information regarding the relevant state of the art can be found in the following literature sites: GB 2,158,437, EP 229,912 and DE 3,247,123.

5

In accordance with the invention on the basis of the use of esteries of the kind mentioned, drilling rinsing fluids, in addition to the advantages already mentioned, are also distinguished by a markedly improved lubricity. This is especially important when the course of the drill rod system and thus also the borehole exhibits deviations from the vertical course of bores 10, for example at greater depths. The rotary drill rod system here easily comes into contact with the borehole wall and digs into it during operation. Ester oils of the kind used as the oil phase according to the invention have a clearly improved lubrication effect than the previously used mineral oils. Herein, a further important advantage lies in the actions performed according to the invention.

15

examples

As the ester oil to form the closed oil phase, lauric acid / n-hexyl ester distilled in the following Examples 1 and 2 and in Comparative Examples 1 and 2 is used. This is a whitish-yellow liquid with a flash point above 165 ° C, a flight point below -5 ° C, a density (20 ° C) of 0.857 to 0.861, an iodine number and an acid number below 1, a water content below 0.3% and the following viscosity data (Brookfield mPas) in the low temperature range: 25 -5 ° C, 22.5 to 25.5; + 2 ° C, 15 to 18; + 5 ° C, 15 to 18; + 10 ° C, approx. 15; 20 ° C, 12 to 14 ° C.

Example 1 In a manner known per se, from the components listed below, a water / oil invert drill rinser is composed, and then the viscosity characteristics of undiluted and aged material are determined:

In DK 170979 B2 H

I 16 I

In Measuring the Viscosity at 50 ° C in a Fann-35 Viscometer from Fa. BAROID DRIL-I LING FLUIDS, INC. In a manner known per se, the plastic viscosity I (PV), flow limit (YP) and gel strength (lb / bbl ft2) are determined after 10 seconds and 10 minutes.

I 5 The measurements are carried out with both the undulating material and the aged material, whereby the aging is carried out by treatment for a period of 16 hours at 135 ° C in auto-I clay - in the so-called Roller-Oven.

In the following composition of the drill rinse fluid is selected:

I H

In 230 ml of ester oil in 26 ml of water

In 6 g of organophilic bentonite ("GELTONE" from Fa. BAROID DRILLING)

IN FLUIDS, INC.) H

In 15 6 g of organophilic lignite ("DURATONE" from Fa. BAROID DRILLING H

IN FLUIDS, INC.) H

In 1 g of lime (0.99 lb / bbl)

In 6 g water / oil emulsifier ("EZ-MUL" from Fa. BAROID DRILLING

IN FLUIDS, INC.) H

In 20 346 g of barite

In 9.2 g CaCl; X 2 H2 O. H

In this recipe, approx. 1.35 g of lime to the limit of 2 lb / bbl.

I The characteristics identified as above with undigested and aged material are given in the following tabular summary.

I Old age I ___ material_ material In plastic viscosity (PV) 28 28 I 30 flow limit (YP) 11 14 I gel strength (lb / 100 ft2) DK 170979 B2 j 17 10 seconds 5 6 10 minutes 7 8

Comparative Example 1 5

The invert drill rinse liquid of Example 1 is combined with the same proportions. However, the lime content is now increased to threefold (3 g (2.96 lb / bbl)).

10 The characteristics of the undiluted and aged material are summarized in the following summary: Unaltered Aged _________ material_ material 15 plastic viscosity (PV) 31 72 flow limit (YP) 8 59 gel strength (lb / 100 ft2) 10 seconds 5 13 10 minutes 7 74. 20

Example 2

With the same ester oil, a particularly high weighted inverted drilling flush fluid is prepared according to the following recipe: 25 184 ml ester oil 10 ml water

2 g of organophilic bentonite ("GELTONE" from Fa. BAROID DRILLING

FLUIDS, INC.)

30 g of organophilic lignite ("DURATONE" from Fa. BAROID DRILLING

FLUIDS, INC.) DK 170979 B2 Η

lg of lime (1.01 lb / bbl) H

10 g Water / Oil Emulsifier ("EZ-MUL" from Fa. BAROID DRILLING ^^ k FLUIDS, INC.) 568 g barite

4.8 g CaCl2 x 2 H2 O. H

As in Example 1, the material numbers are determined for unpowered and for aged material.

The values found are compiled in the following tabular summary: Undiluted Aging _ Material_Material Plastic Viscosity (PV) 20 81 Flow Limit (YP) 12 16 ^^ k 15 Gel Strength (lb / 100 ft2) 10 Seconds 8 8 10 Minutes 10 11 In this recipe answers approx. 1.04 g of lime to the limit of 1 lb / bbl.

H

Comparative Example 2

The highly charged formula of Example 2 is reassembled. However, the lime content is now raised to twice that (2 g (2.02 lb / bbl)).

Again, the known data for unpowered and aged material is determined. They are listed in the following composition: Undiluted Aging 30 material material plastic viscosity (PV) 78 73 DK 170979 B2 19 flow limit (YP) 37 59 gel strength (lb / 100 ft2) 10 seconds 12 18 10 minutes 16 27 5 I the following Examples 3 and 4 are used as ester oil to form the closed oil phase an ester mixture of the substantially saturated fatty acids on the basis of palm kernel and 2-ethylhexanol, which for the most part goes back to C12 / 14 fatty acids and corresponds to the following specification: 10 C8: 3.5 to 4.5% by weight

ClO 3.5 to 4.5% by weight

Cn 65 to 70 wt% C] 4 20 to 24 wt% C 2% by weight

Ci g 0.3 to 1% by weight.

The ester mixture is available as a light yellow liquid with a flash point above 165 ° C, a flight point below -10 ° C, a density (20 ° C) of 0.86 and an acid number below the 0.3.1 low temperature range, the ester mixture exhibits the following viscosity data (Brookfield mPas): -5 ° C, 20 to 22; 0 ° C, 16 to 18; + 5 ° C, 13 to 15; + 10 ° C, approx. 11; 20 ° C, 7 to 9.

. in

Example 3 25

As described in the foregoing examples, from the components listed below, a water / oil invert drill rinser is composed, and then the viscosity characteristics of uncured and aged material are determined.

In addition, the following composition of the drilling rinse fluid is selected: 30 230 ml ester oil

DK 170979 B2 H

H

6 g of emulsifier 1 ("INVERMUL NT" from one applicant (Baroid)) 26 g of water 6 g of organophilic bentonite ("GELTONE") 12 g of organophilic lignite ("DURATONE")

1.5 g of lime (1.44 lb / bbl) H

6 g of emulsifier 2 ("EZ-MUL") 346 g of barite

9.2 g CaCl2 x 2 H2 O H

10 The distinguishing features of the aged and the aged material are given in the following tabular summary.

Undiluted Mature material material 15 plastic viscosity (PV) 37 30 flow limit (YP) 16 14 gel strength (lb / 100 ft2) 10 seconds 7 5 10 minutes 10 9

H

Example 4

A water / oil invert drilling flushing liquid containing 40% water is made up using the last described ester oil according to the following recipe: 350 ml ester oil 20 g emulsifier ("EZ-MUL")

8 g of organophilic lignite ("DURATONE") H

4 g of lime (2.02 lb / bbl) H

6 g organophilic bentonite ("GELTONE") 234 ml water DK 170979 B2 21 99 g CaCl2 x 2 H2 O 150 g barite

The unspecified characteristics for plastic and aged material regarding plastic viscosity 5 and float limit are as follows: Unsold aged material material plastic viscosity (PV) 33 32 10 flow limit (YP) 77 56

Claims (15)

1. Use of selected in the temperature range ffa 0 to 5 ° C flow and pump 5 capable esters of monofunctional alcohols of 2 to 12, in particular 4 to 12 carbon atoms, and aliphatic, saturated monocarboxylic acids of 12 to 16 carbon atoms or oil phase or at least a substantial portion of the oil phase of invert drilling mud suitable for an environmentally sensitive off-shore utilization of petroleum or natural gas deposits and containing in a closed oil phase a dispersed aqueous phase together with an alkali reserve, emulsifiers, gravitating agents , fluid-loss additives and, if desired, additional usual additives. Embodiment according to claim 1, characterized in that esters are used which, for at least 60% by weight - calculated in relation to carboxylic acid mixture - are esters 15 of aliphatic C 1-6 monocarboxylic acids and, if desired, are derived from the residue of inferior amounts of short-chain aliphatic and / or longer-chain and in this case especially cn and / or several times olephemically unsaturated monocarboxylic acids. Embodiment according to claim 1 or 2, characterized in that esteries are used in alkaline-set drilling rinses with an alkali reserve, in which, as alkali reserve, lime and / or metal oxides of the zinc oxide type are preferably present. Embodiment according to claim 1, 2 or 3, characterized in that the ester oils are used in drilling rinses containing lime as an alkali reserve in an amount of not more than 5.71 g / l (2 lb / bbl) (lime / drilling rinsing liquid). . Embodiment according to any one of claims 1 to 4, characterized in that esters are used in the oil phase of drilling muds which have a Brookfield (RTV) viscosity in the range of not more than 50 mPas in the temperature range of 0 to 5 ° C, preferably not more than 40 mPas and 30 in particular at a maximum of 30 mPas. 23; DK 170979 B2 Embodiment according to any one of claims 1 to 5, characterized in that the esters used in the drilling mud have solidification values (flow and solidification point) below -10 ° C, preferably below -15 ° C, and have flash points above 100 ° C, preferably above 150 ° C. , 5 Embodiment according to any one of claims 1 to 6, characterized in that the carboxylic acids present in the ester or in the esterbirh are at least predominantly chained and preferably of vegetable origin, and in particular are derived from corresponding triglycerides, such as coconut oil, palm kernel oil and / or babassu oil. Embodiment according to any one of claims 1 to 7, characterized in that the esters are used in drilling flushing liquids containing in the inert drilling flush mud together with the closed ester-based oil phase the finely dispersed aqueous phase in amounts of 5 to 45% by weight, preferably in amounts. of 5 to 25% by weight. Embodiment according to any one of claims 1 to 8, characterized in that the alcohol residues of the esters used are derived from straight chain and / or branched saturated alcohols having preferably 4 to 10 carbon atoms. '! Embodiment according to any one of claims 1 to 9, characterized in that the alcohol components of the esters used are also of vegetable and / or animal origin and are recovered by reductive hydrogenation of corresponding carboxylic acid esters. M 11. Mineral oil-free invert drilling fluids suitable for off-shore utilization of petroleum or natural gas deposits and contained in a closed ester oil-based oil phase containing a dispersion aqueous phase together with an alkali reserve, emulsifiers, thickeners, gravitators, fluid loss additives and, if desired, additional usual additives, characterized in that the oil phase comprises at least a substantial proportion of esters of monofunctional alcohols of 2 to 12 carbon atoms and aliphatic saturated monocarboxylic acids of 12 to 16 carbon atoms, These esters in the oil phase in the temperature range from 0 to 5 ° C have a Brookfield (RVT) viscosity of not more than SO mPas. Drilling flushing fluid according to claim 11, characterized in that the inverting drilling flushing liquid is slightly alkaline and thus contains an alkali reserve, although preference is given to the use of highly hydrophilic bases such as alkali hydroxide or highly hydrophilic amines such as diethanolamine. . Drilling flushing fluids according to claim 11 or 12, characterized in that, as an alkali reserve, lime and / or metal oxides of the zinc oxide type are present, lime amounts in the range up to 5.71 g / l (2 lb / bbl) (lime / drilling rinse fluid) is preferred. Drilling flushing fluids according to claims 11 to 13, characterized in that they have a plastic viscosity (PV) in the range of 10 to 60 mPas and a flow limit (Yield Point YP) in the range of 2.5 to 20 Pa. (5 to 40 lb / 100 ft 2) - determined at 50 ° C. Drilling flushing fluids according to claims 11 to 14, characterized in that the dispersed amount of water is 5 to 45% by weight, preferably 5 to 25% by weight, and dissolved contains in particular salts of the species CaCU and / or KCl. H