DK170786B1 - Use of esteries in drilling fluids - Google Patents

Description

in DK 170786 B1

BACKGROUND OF THE INVENTION The present invention relates to novel ester-based drilling rinses and invert drill-rinsed sludge, which are characterized by high ecological acceptability, together with good condition and use characteristics. An important area of application of the novel drilling rinsing systems is offshore 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 present-to-unknown drill shine systems is particularly important 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 boron oil ions on the basis of the invention.

Liquid rinsing systems for downhole drilling during application of the loosened drilling materials are, as is well known, 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 drilling or for water-sensitive breakthroughs.

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 of water / oil emulsions, ie. that the aqueous phase is distributed heterogeneously finely dispersed in the closed oil phase. To stabilize the overall system and to adjust the desired operating characteristics, several additives can be used, in particular emulsifiers or emulsifier systems, gravitational agents, flux loss additives, alkali reserves, viscosity regulators and the like. For details, reference is made, for example, to that of P. A. Boyd et al. published article "New Base Oil Used in Low-Toxicity Oil Muds", Journal of Petroleum Technology, 1985, pages 137 to 142, and RB Bennet, "New Drilling Fluid Technology - Mineral Oil Mud", Journal of Petroleum Technology, 1984, pages 975 to 981, and the literature cited therein.

Oil-based drilling cloud 1 liquids were initially built up of diesel fuel fractions with a content of aromatics. 10 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" - as closed oil phase, referring here to the literature cited above. 15 Although some progress has been made in this way from the exclusion of the aromatic compounds, a further reduction of the environmental problem - triggered by drilling flush liquids of the kind in question - seems imperative. This is particularly valid in the downturn of off-shore drills 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 acknowledged the importance of ester-based oil phases in solving this problem.

Thus, US Patent Nos. 4,374,737 and 4,481,121 disclose oil-based drilling mud fluids in which non-contaminated oils are to be used. As non-polluting oils are mentioned next to each other and as equivalent aromatic free mineral oil fractions and peanut oil, soybean oil, flaxseed oil, corn oil, rice oil or oils of animal origin, such as whale oil. Everywhere, with respect to the esters of vegetable and animal origin mentioned herein, triglycerides of natural fatty acids are known, which are known to have a high environmental compatibility and in relation to hydrocar bon fractions - even when they are aromatically free - have a clear superiority from ecological considerations.

3 DK 170786 B1

Interestingly, however, no example in the aforementioned U.S. Patents discloses the use of such natural esteries in invert-boric shells of the kind herein. Mineral oil fractions are used everywhere as a closed oil phase.

5

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 maintained for the broadly demanding temperature range from first 0 to 5 ° C and secondly to 250 ° C and above.

In U.S. Patent No. 4,481,121, in its common description 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 monoalcohol ester of very pure tall oil fatty acids. A 20 here named for the first time ester of a monofunctional alcohol and monofunctional or carboxylic acids is indicated as equivalent to triglycerides of natural origin and / or aromatically free hydrocarbon fractions.

25 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 discussed below assume that in reality it is possible to produce oil-based invert flushing fluids of the present invention on the basis of high environmental acceptability ester, as with respect to their storage and application behavior corresponds to the best known oil-based invert flushing systems, yet it has the additional advantage of increased environmental acceptability. Two important acknowledgments master the teachings of the invention: DK 170786 B1

For the construction of mineral oil-free oil-based invert rinses, 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 esters of this type do not in fact behave like the previously used hydrocarbon mineral oil fractions. The esters of the monofunctional components disclosed herein undergo a partial hydrolysis in the practical application. Thereby free fatty acids are formed. These, in turn, react with the alkaline constituents of the kind in question which are always present in drilling rinsing systems - e.g. with the alkali reserve used for corrosion protection - to form the corresponding salts. Salts of highly hydrophilic bases and the naturally occurring acids or oils of natural origin in the region of approx. However, C6 to C24 are, as is well known, compounds with relatively high HLB values which lead in particular to the setting and stabilization of oil / water emulsions. As is well known, the washing and cleaning 20 makes use of this technique to a large extent.

However, the formation of undesirably large amounts of such oil / water emu1 gator systems will generate the water-oil emulsions required by the invention and thus lead to disruption. The teachings disclosed hereinafter in accordance with the invention describe how practically useful ester-based invertebrate rinse fluids can be used despite these system-independent difficulties.

Accordingly, the invention relates in a first embodiment to the use of selected, in the temperature range of 0 to 5 ° C, flowable and pumpable esters of monofunctional alcohols of 2 to 12 carbon atoms and olefinic one and / or several times unsaturated monocarboxylic acids of 16 to 24 carbon atoms or mixtures thereof with minor amounts of other, especially saturated monocarboxylic acids having 16 to 24 carbon atoms as an oil phase or at least a substantial portion of the oil phase of the invert borehole sludge containing in a closed oil phase a dispersed aqueous phase and emulsifiers, gravitating agents , fluid-loss additives and, if desired, additional usual additives together with an alkali reserve, with the proviso that the use of highly hydrophilic bases such as 5 alkali hydroxide and / or diethanolamine is waived. As an alkali reserve, especially for protection against penetration of CO2 and / or H2S in the drilling cloud 11 liquid and thus for protection against corrosion, lime (calcium hydroxide or lime) is frequently added. The use of a side lime addition as an alkali reserve is possible within the scope of the invention. However, care should be taken here to incorporate only relatively limited amounts of this alkaline component. The highest amount of the lime addition is in the preferred embodiment of the invention of 5.71 g / l (2 lb / bbl) (lime / oil rinse liquid) and thus clearly below the 15 values which are usually used in oil-based invert rinse fluids.

The invention relates in a further embodiment to mineral oil-free invert-boric liquids suitable for off-shore utilization of petroleum or natural gas deposits and contains a dispersed aqueous phase of ester oils containing a dispersed aqueous phase together with emulsifiers, thickeners, gravitators. agents, fluid loss additives and, if desired, additional usual additives. The present novel drilling rinsing systems are characterized in that the oil phase comprises at least a substantial part of esters of monofunctional alcohols of 2 to 12 carbon atoms and olefinic 1 and / or several times unsaturated monocarboxylic acids of 16 to 24 carbon atoms, and furthermore, the water / oil emulsion is weakly alkaline conditioned and, upon lime addition, this alkali reserve preferably does not exceed amounts of 5.71 g / l (2 lb / bbl) (lime / oil rinse liquid). It may be preferable that the lime content be slightly below this limit value.

35 In the following, we will first begin by looking at the esterols selected according to the invention, which determine, or at least as a substantial part, constitute the closed oil phase of the invertebrates in the breast.

6 DK 170786 B1

As already stated, a problem-solving criterion consists in the selection of esters to be assigned to the class of turnover products of monofunctional carboxylic acids with monofunctional alcohols. However, the invention, in addition to this class, is intended to use, or at least predominantly, carboxylic acids in the aforementioned range from 16 to 24 carbon atoms. The carboxylic acids may be derived from unbranched or branched hydrocarbon chains, the straight chains being of particular importance. Monocarboxylic acids of this kind and in the present range from 16 to 24 carbon atoms or their esters are considered to be predominantly saturated hydrocarbon compounds because of their relatively high solidification value. However, esters of the kind in question are, in that case, even flowable and pumpable down to temperatures in the range of 0 to 5 ° C, when a sufficient degree of o 1ef i n in so-called unsaturated ester constituents is guaranteed. Accordingly, in the preferred embodiment of the invention, esters of the kind described herein are used which are derived from olefinic unsaturated carboxylic acids in the C 1 -24 · important nature for more than 70 wt% and preferably more than 80 wt%. Starting materials lead to carboxylic acid mixtures which, for at least 90% by weight, contain olefinically unsaturated carboxylic acids in the C range mentioned herein. The unsaturated cationic acid may be one and / or several times olefinically unsaturated. In 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 also a triple ethylenic double bond per carboxylic acid molecule plays a certain role. Details of this are further given below.

The selection of such a comparatively high proportion of unsaturated cai- bicylic acid in the esteryls ensures - in connection with the selection according to the invention of esters of monofunctional reactants - that the esteryls and finally the finished invert emulsions fulfill the rheological properties required in practice. even at lower temperatures. The relatively strongly unsaturated esters of the C-number range from 16 to 24 of the monocarboxylic acid moiety used in the preferred embodiment have, in the preferred embodiment, solidification values (flow point and set point) below -10 ° C and especially below -15 ° C. Despite this high mobility at low temperatures, by using the molecular size of the ester prescribed by the invention, the flash points of the ester oils are sufficiently high. Oe is at least 80 ° C, but generally exceeds the temperature limit of approx. 100 * C. Preferably, esteries 10 having flash points above 160 ° C are used, since easily movable esteries of the kind mentioned can also be produced, whose flash points are at 185 ° C or higher.

At the same high molecular flash points determined by the molecular size, it can simultaneously be ensured that the viscosity values comply with the usual standard values. Thus, for preferred esteries of the type of Brookfield (RTV) - we are shot in the density in the temperature range of 0 to 5 ° C at values not above 55 mPas and preferably at values not exceeding 45 20 mPas or below. It is possible to set values in the range of 30 and even lower, for example in the range of 20 to 25 mPas in the specified temperature range.

Within the scope of the unsaturated esterols for use according to the invention, two subclasses of particular importance may be composed.

The first of these subclasses is based on unsaturated Ci6 ~ 24_ monocarboxylic acids, which for no more than approx. 35 guard vs-30 coming are twice and possibly several times olefinically unsaturated. Thus, the content of several times unsaturated carboxylic acid residues in the ester oil is relatively limited. However, within the scope of this subclass, it is preferred that the carboxylic acid residues for at least ca. In the case of 60 guard FC, mono-olefinically unsaturated.

Unlike the first mentioned subclass mentioned above, the second substantially significant subclass of esteryls derived from DK 170786 B1 8 such Ci6-24 "monocarboxylic acid:) landings which are more than 45% by weight and preferably more than 55% by weight % is derived from two and / or several times olefinically unsaturated acids in said C-antigenic region.

5

The most important ethylenically monounsaturated carboxylic acids in the subject area are the hexadecenoic acid (palmitic acid, C16), the oleic acid (Cie), the related ricinoleic acid (C8), and the uracetic acid (C22). The most important two-unsaturated carboxylic acid in the present 10 area is the linoleic acid (Cie) / and the most important three times ethylenically unsaturated carboxylic acid is the linolenic acid (Cis) ·

Selected examples of the ester type unsaturated carboxylic acid / monoalcohol can be used as ester oil according to the invention. An example of this is the esters of the oleic acid, such as of the oleic acid oxybutyl ester species. For reasons of system rheology and / or for accessibility, it is frequently desirable to use acid mixtures. Herein lies something important for meeting the above specifications for the two under classes of preferred esters.

The first of these two subclasses is distinguished by the fact that their content of two and more times unsaturated acids is limited and does not exceed approx. 35%. Plant oils of natural origin which, by their saponification or transesterification, lead to mixtures of carboxylic acids or carboxylic esters of the kind required herein are, for example, palm oil, peanut oil, castor oil and especially rapeseed oil. Both rapeseed oil species with high erucic acid content, as well as the more modern rapeseed oil yields with reduced erucic acid content and therefore increased oleic acid content, are considered.

Therefore, ester oils based on this definition of the first sub-35 class may already be of particular importance, because here problems of oxidation instability encountered in practical operation have been mitigated. In the practical work, the 9 DK 170786 B1 drilling cooler is continuously pumped in circulation and thereby constantly - frequently with large surface area and at least slightly increased temperatures - is brought into contact with the oxygen of the air in order to dispose of the transported 5 drilling material, for example by screening.

However, also carboxylic acid mixtures belonging to the second subclass mentioned above have considerable practical importance for the use according to the invention. The reason for this is not least their wide availability in the context of natural fats of vegetable and animal origin. Classic examples of high carboxylic acid oils in the Cje-ie or Cjg_22 ° 9 range at the same time at least approx. About 35% of at least twice ethylenically unsaturated carboxylic acids are the cotton seed oil, soybean oil, sunflower oil and linseed oil. Also, the tall oil acids isolated by cellulose extraction fall under this range. However, used materials of this latter origin are usually distinguished by more or less large additional resin constituents. A typical animal application material for the recovery of suitable carboxylic acid mixtures is fish oil, especially the herring oil.

As already stated, the esters used according to the invention may be selected individually determined esters of the above definition. However, usually mixtures of esters of corresponding monocarboxylic acids and monoalcohols are present. Particularly within the scope of the invention are such mixtures which, firstly, correspond to the viscosity condition required by the invention, especially also at lower temperatures, and secondly, for at least 50 to 51%, constitute the monofunctional esters of the olefinically one and / or several times unsaturated carboxylic acids having 16 to 24 carbon atoms. Ester constituents and especially again carboxylic acid esters of monofunctional alcohols and monofunctional carboxylic acids of other constitution are admissible as subordinate blend ingredients, provided that the requirements for the substance blend properties are met. This is important for the use of carboxylic acid mixtures of natural origin. In general, such natural uses also contain more or less large proportions of saturated carboxylic acids and therefore frequently also just carboxylic acids in the region of C iø iø. Saturated fatty acids of this kind or their esters present slightly rheological difficulties due to the relatively high melting points. . Accordingly, according to the invention, it may be preferred that saturated carboxylic acid residues in the C Cg / µg range do not exceed 20% by weight and especially not more than 10% by weight in the esteryls.

10

In contrast, the presence of particularly saturated carboxylic acid residues in the C number range is below, especially in the range c12 / 14 · The content of such lower fully saturated fatty acids frequently present here in practice, in inferior amounts, is frequently valuable mixing components. with respect to the object of the invention. Their esters are, under practical conditions of use, not oxidation-prone, and their rheological properties exceed the object of the invention to replace the pure hydrocarbon oils used up to now with esteryls or esteryl fractions.

According to the teachings of the invention, the alcoholic residues of the esters or ester mixtures 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. Cjq is of particular importance. The alcohols may also be of natural origin and in that case have usually been recovered from 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. Both on the side of the monoalcohols and on the side of the monocarboxylic acids the corresponding materials of natural origin may be used, partly or exclusively, for similar components of synthetic origin. Typical examples of alcohols are the corresponding oxoalcohols (branched alcohols) or the linear alcohols recovered by the Ziegler method. Also, especially monocarboxylic acid components present in carboxylic acid mixtures may be derived from the petrochemical synthesis. However, advantages are related to the materials of natural origin used, in particular to the lower toxicological values detected, the degradability and the availability. For the eventually desired disposal of the used oil cloud liquid by natural route, it is important that the esteries of the kind described herein be degraded by both aerobic and anaerobic routes.

However, an important limitation is associated with the use of these esterols in invert oil sludge of the kind in question. This concerns the above-mentioned difficulty that the carboxylic esters are in principle hydrolysis-prone and thus must behave differently from the pure hydrocarbon oils used so far.

Invert drill rinsing mud of the present invention usually contains, together with the closed oil phase, the finely dispersed aqueous phase in amounts of approx. 5 to 45% by weight and preferably in amounts of about 5 to 25 weight *. The area from approx. 10 to 25% by weight of dispersion aqueous phase may be of particular importance. This condition based on the constitution of conventional drilling fluid 25 also applies to the invert flushing fluids herein. It is obvious that in the continuous practical operation, disturbances of the equilibrium may occur in the phase-phase systems which are conditioned by a partial ester saponification.

30

The situation is made more difficult by the fact that bore sky 1 liquids of the kind in question always contain an alkaline reserve in practice. This alkali reserve is of major importance as a corrosion protection against unexpected penetration of acidic gases, namely 35 CO2 and / or H2S in particular. This corrosion problem regarding drill rod systems requires safe adjustment of pH values at least in the slightly alkaline range, for example pH 8.5 to 9 and higher values.

12 DK 170786 B1 In oil-based liquids on the basis of pure hydrocarbon cargo in ounces such as oil phase, in practice, generally, without concern, highly alkaline and, in addition, highly hydrophilic additives of an inorganic or organic nature are used. In addition, the alkali hydroxides, and especially most of the sodium hydroxide or highly hydrophilic organic bases, may be of particular importance, with diethanolamine and / or triethanolamine being particularly common additives for the capture of H2S contaminants. In addition to and / or in place of the highly hydrophilic inorganic and organic bases mentioned herein, lime (lime) or even weaker basic metal oxides, in particular zinc oxide or similar zinc compounds, have significant importance as an alkali reserve. Precious lime is widely used as an inexpensive alkalizing agent. Thus, relatively large quantities are used which are, for example, 1 to 10 1b / bbl (lime / oil rinse liquid) or even higher values.

The use of ester cloud 11 liquids of the kind described herein requires a deviation from the previous practice with respect to these variables. Of course, here it must also be ensured that the drilling flush pH of the liquid is kept at least in the slightly alkaline region and that a sufficient amount of all potassium reserve is available for unexpected penetration of especially acidic gases. In doing so, however, it is ensured that ester hydrolysis 25 at such an alkali content is not adversely promoted and / or accelerated.

Thus, in the preferred embodiment of the actions performed in accordance with the invention, it is ensured that substantial amounts of highly hydrophilic bases of inorganic and / or organic nature are not used in the oil rinse liquid. In particular, according to the invention, the use of alkali hydroxides or highly hydrophilic amines of the diethanolamine species and / or triethanolamine species is waived. Lime can be effectively used as an alkaline reserve. In that case, however, it is appropriate to limit the maximum amount of lime used to approx. 2 lb / bbl, whereby it may be preferable to work with drilling mud fillings of lime slightly below, for example in the range of approx. 1 to 1.8 lb / bbl (lime / drill rinse fluid). In addition to or in place of the lime, other alkaline reserves of a known kind can be used. In particular, the less basic 5 metal oxides of the zinc oxide species and other similar zinc compounds must be mentioned. However, even when using such acid scavengers, excessive amounts are used to prevent an undesirable premature aging of the drill-rinse fluid - associated with an increase in viscosity and thus deterioration of the rack and in its properties. With the aid of this detail in the actions according to the invention, the emergence of undesirable amounts of highly effective oil / water emulsifiers is prevented or at least limited such that the good rheological use values remain maintained for a sufficient period of time, even at the same time. thermal aging during operation. In relation to the recommendations so far maintained in the field of theoretical considerations according to the state of the art, there is a decisive gain here, which at first only allows the practical exploitation of the low toxic properties of the 20 esters in question.

In accordance with the invention, defined in the temperature range of 0 to 5 * 0 flowable and pumpable esters on the basis of the olefinically unsaturated monocarboxylic acids of 16 to 24 carbon atoms 25, in the closed oil phase of the drilling mud, generally comprise at least about half of the oil phase. Preferred, however, are such oil phases which, for the most part, contain esters or ester mixtures of the kind specified in the invention and in a particularly important embodiment of the invention practically consist of such esters. Particularly selected other ester oil fractions, as described in the parallel patent application No. 1176/91, are suitable as mixing components for mixing with the ester defined in the invention. The invention also encompasses mixtures with such selected 35 other esteries.

Regarding the rheology of preferred invert drilling fluid according to the invention, the following rheological data apply: plastic 14 DK 170786 B1 viscosity (PV) in the range of approx. 10 to 60 mPas, preferably from ca. 15 to 40 mPas, float limit / Yield

Point YP) in the range of 2.5 to 20 Pa (5 to 40 lb / 100 ft 2), preferably 5 to 12.5 Pa (10 to 25 lb / 100 ft 2) - each time determined at 50 ° C. For the determination of these five 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 details according to the prior art which were initially mentioned and described in detail, for example in manual 10 ", apply in detail. Manual Of Drilling Fluids Technology "by one applicant is BAROID DRILLING FLUIDS, INC., Especially in the" Mud Testing> Tools and Techniques "chapter, as well as" Oil Mud Technology "which is freely available to the interested professional. In summary, for purposes of completing the Explanation 15 of the invention, the following may be said: Practically useful emulsifiers are systems which are suitable for forming the required water / oil emulsions. Particularly considered are selected oleophilic fatty acid salts, for example 20 such on the basis of amidoamine compounds. Examples thereof are described in the aforementioned U.S. Patent No. 4,374,737 and the literature cited therein. A particularly suitable type of emulsifier is that of applicant Baroid Drilling Fluids, Inc. product sold under the trade name "EZ-MUL".

25

Emulsifiers of this type are commercially sold as highly concentrated active ingredient compositions and may, for example, be used in amounts of approx. 2.5 to 5 weight *, especially in amounts of about 3 to 4 weight * - calculated in relation to 30 ester phase.

As a fluid-loss additive and, in particular, to form a dense coating of the drilling walls with a largely liquid-impermeable 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 approx. 5 to approx. 7% by weight - calculated in relation to the ester phase.

15 DK 170786 B1 In drill rinsing liquids of the kind in question, the commonly used viscosity generator is a cat in on modified so-called finely divided organophilic bentonite, which can be used especially in amounts from approx. 8 to 10 lb / bbl or in the range of approx. 2 to approx. 4% by weight, 5 calculated in relation to the esteryla phase. In practice, the usually used gravity-reducing agent for adjusting the necessary pressure equalization is barite, whose addition amounts are adjusted to the expected conditions of the bore. For example, by adding barite, it is possible to increase the specific gravity of the drilling cloud 11 fluid to values in the range up to approx. 2.5 and preferably in the range of about 1.3 to 1.6.

The dispersed aqueous phase is filled with soluble salts in nvert-drilling rinses of the kind in question. For the most part, calcium chloride and / or potassium chloride are used here, with the saturation of the aqueous phase with the soluble salt being preferred at room temperature.

The aforementioned emulsifiers or emulsifier systems 20 may also serve to improve the oil wettability of the inorganic weight-giving materials. In addition to the aforementioned aminoamides, mention is made, as further examples, of alkyl-benzenesulfonates and of midazole-linked Iser. Further disclosures relating to the prior art are found in the following literature sites: GB 2,158,437, EP 229,912 and DE 32 47 123.

In accordance with the invention, by utilizing esteries of the aforementioned kind, drilling mud 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 for drilling, for example at greater depths and thus also the borehole, shows deviations from the vertical course. The rotary drill rod system here easily comes into contact with the borehole wall 35 and digs into it during operation. Ester oils of the kind used as an oil phase according to the invention have a clearly better lubrication effect than the mineral oils used hitherto. Herein lies a further important advantage of the actions performed according to the invention.

EXAMPLES

Example 1

An invert drill flush case is prepared on the basis of an undiluted isobuty1 rapeseed oil ester as a closed oil phase. This rapeseed oil ester is based on a mixture of predominantly unsaturated, straight-chain carboxylic acids, corresponding to approx. to the following distribution: 60% oleic acid, 20% linoleic acid, 9 to 10% linolenic acid, olefinically unsaturated C20 / 22 "monocarboxylic acids ca Density (20 ° C) 0.872 g / cm 3; f1 yield point below -15 ° C; flash point (DIN 51584) above 180 ° C; acid number (DGF-C-V 2) 1,2; viscosity at 0 ° C 32 mPas, viscosity at 5 ° C 24 mPas; no aromatic compounds content.

20

An invert drill rinser is prepared in a conventional manner using the following blend ingredients: 230 ml rapeseed oil fatty acid ester 25 ml ml water 6 g organophilic bentonite ("GELTONE" from the company BAROID DRILLING FLUIDS, INC.) 0.2 g lime 6 g water / oil emulsifier ("EZ-MUL" from the company BAROID 30 DRILLING FLUIDS, INC.) 340 g Baryt

9.2 g of calcium chloride, 2 H2 O

20 g of organophilic lignite ("DURATONE11 from the company BAROID

DRILLING FLUIDS, INC) 35

To begin with, the viscosity (PV), the flow limit (YP) and the gel strength after 10 seconds and 10 minutes are determined by means of viscosity measurement at 50 ° C on undigested material.

In addition, the invert-bore liquid is aged for 16 hours at 125 ° C in 5 autoclaves in the so-called "Rol-Oven" for the purpose of assessing the influence of temperature on the emulsion stability. Then the viscosity value in the irons is again determined at 50 ° C.

The following values are obtained; 10 unsold aged _material_material

Plastic Viscosity (PV) 35 62 15

Flow limit (YP) 21 24

Gel strength (lb / 100 ft *) 10 seconds 12 12 20 10 minutes 14 15

Comparative Example 1

An invert drill flushing liquid according to the specifications of Example 1 is reconstituted. Now, however, the amount of lime is raised to the value of 4 g and is thus drastically raised above the limit value of approx. 2 lb / bbl.

Here, too, the viscosity values and gel strength are determined for 30 unsalted and aged materials. The following numerical values are obtained; non-aged aged _ material_ material 35 Plastic viscosity (PV) 41 not determined 18 GB 170786 B1

Flow limit (YP) 22 does not determine! Ig

Gel strength (lb / 100 ft *) 5 10 seconds 11 74 10 minutes 17 72

Example 2 An inverted oil phase inverted drilling fluid is again prepared. The oil phase is distilled oleic acid isobutyl ester which exhibits the following characteristic data: density (20 ° C) 0.86 g / cm 3; viscosity (20 ° C) 8 to 10 mPas; floating point below -25 ° C; flash point (DIN 51584) above 185 ° C; acid number 15 (DGF-C-V 2) below 1; no aromatic compounds content.

A borehole wash was composed of the following composition: 20 210 ml isobutyl oleate 6 g fatty acid emulsifier ("INVERMUL" from BARO ID DRILLING FLUIDS, INC.) 6 g organophilic bentonite ("GELTONE" from BAR0ID DRILLING FLUIDS, INC. )

25 13 g of organophilic lignite ("DURAT0NE" from the company BAR0ID

DRILLING FLUIDS, INC.) 1 g lime

3 g water / oil emugator ("EZ-MUL" from the company BAROID

DRILLING FLUIDS, INC.) 30 270 g Baryte 58.2 g matte aqueous CaCl2 solution

The plastic viscosity, yield strength and gel strength after 10 seconds and 10 minutes are determined as in Example 1 for 35 aged and aged (16 hours at 125 ° C in Roller-Oven) material.

The values thus measured are summarized below. In the recipe used here, approx. 1.2 g of lime to the limit of 2 lb / bbl.

19 DK 170786 B1 unsold sided ___material_material

Plastic Viscosity (PV) 46 41 5

Flow limit (YP) 35 32

Gel strength (lb / 100 ft2) 10 seconds 17 18 10 10 minutes 21 29

Comparative Example 2

With the recipe of Example 2, an inert oil emulsion is again prepared. However, the lime addition is now increased to 2 g and thus clearly exceeds the limit value of 2 lb / bbl. The values for plastic and aged material for the plastic viscosity, the yield strength and the gel strength are summarized below: 20 non-aged ____ material a 1 e_ material

Plastic Viscosity (PV) 53 46 25

Flow limit (YP) 61 45

Gel strength (lb / 100 ft2) 10 seconds 33 24 30 10 minutes 40 29 35

Claims (15)

Use of selected, in the temperature range from 0 to 5 ° C, flowable and pumpable esters of monofunctional alcohols of 2 to 12 carbon atoms and olefinic one and / or several times unsaturated monocarboxylic acids of 16 to 24 carbon atoms as an oil phase or in the least significant proportion of the oil phase of invert drilling mud suitable for environmentally gentle off-shore utilization of petroleum or natural gas bodies and containing in a closed oil phase a dispersion aqueous phase as well as emulsifiers, gravitational agents, fluid loss additives and if desired, additional usual additives, together with an alkali reserve, with the proviso that the use of highly hydrophilic bases such as alkali hydroxide and / or diethanolamine be waived and that any calcium addition present be limited to a maximum of 5.71 g / l. (2 lb / bbl) oil rinse liquid. Embodiment according to claim 1, characterized in that esters are used which are derived for more than 70% by weight, preferably for more than 80% by weight and especially for more than 90% by weight. of olefinically unsaturated carboxylic acids in the Cig-24 'range Method according to claim 1 or 2, characterized in that the esters used in the drilling mud have solidification values (flow point and set point) below -10 ° C, preferably below -15 ° C, and flash points above 100 ° C, preferably above 160eC. An embodiment according to claims 1 to 3, characterized in that the esters used in the drilling mud in the temperature range of 0 to 5 ° C have a Brookfield (RVT) viscosity of not more than 55 mPas, preferably not more than 45 mPas. DK 170786 B1 Embodiment according to claims 1 to 4, characterized in that the unsaturated c6-24 "mono-carboxylic acid residues present in the ester for no more than 35% by weight are derived from two and more times olefinically unsaturated acids, and preferably for at least approx. 60% by weight are once olefinically unsaturated. Embodiment according to claims 1 to 4, characterized in that the C6-24 mono carboxylic acids present in the ester mixture are more than 45% by weight and preferably more than 55% by weight are derived from 2 and / or several times olefinically unsaturated acids. Embodiment according to claims 1 to 6, characterized in that the saturated carboxylic acids present in the ester mixture in the region Cig / ig do not constitute more than 20% by weight and in particular not more than 10% by weight, but preferably are in the lower C-number range. . Embodiment according to claims 1 to 7, characterized in that the carboxylic acids present in the ester or ester mixture are at least predominantly straight-chain and preferably of vegetable and / or animal origin, and in particular are derived from vegetable triglycerides. origin and / or fish oils or fats. Embodiment according to claims 1 to 8, characterized in that the esters are used in drilling flushing liquids which in the invert drilling flush slurry together with the closed ester-based oil phase contain the finely dispersed aqueous phase in amounts of 5 to 45% by weight, preferably of 5 to 25%. weight%. Embodiment according to claims 1 to 9, characterized in that the alcohol residues of the esters used are derived from 30 straight and / or branched saturated alcohols having preferably 4 to 10 carbon atoms. DK 170786 B1 11. Mineral oil-free inverted rinsing 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 emulsifiers, thickening agents, gravitational agents, fluid loss additives and, if desired, additional usual additives, characterized in that the oil phase is formed for at least a substantial proportion of esters of monofunctional alcohols of 2 to 12 carbon atoms and olefinic 1 and / or 10 several times unsaturated monocarboxylic acids of 16 to 24 carbon atoms, furthermore, the water / oil emulsion is conditioned slightly alkaline and, upon lime addition, this alkali reserve does not exceed amounts of 5.71 g / l (2 lb / bbl) (lime / oil rinse liquid), but preferably is slightly below. 12. Invert drilling flushing fluid according to claim 11, characterized in that no highly hydrophilic bases such as alkali hydroxides or highly hydrophilic amines such as diethanolamine are present in the oil flushing liquid, but that, in addition to or instead of lime, there are limited amounts of 20 metal oxides. of the zinc oxide species as an alkaline reserve. Drilling flushing fluids according to claim 11 or 12, characterized in that they have a plastic viscosity (PV) in the range of approx. 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 ft2) - 25 determined at 50 ° C. Drilling flushing fluids according to claims 11 to 13, characterized in that their disperse water content is 5 to 45% by weight, preferably 10 to 25% by weight, and dissolved contains in particular salts of the species CaCl2 and / or KCl1. Drilling flushing fluids according to claims 11 to 14, characterized in that the oil phase of the invert sludge in the temperature range from 0 to 5 ° C has a Brookfield (RVT) viscosity below 50 mPas, preferably not above 40 mPas.