EP0462152A1

EP0462152A1 - Invert drilling muds

Info

Publication number: EP0462152A1
Application number: EP90904275A
Authority: EP
Inventors: Heinz Müller; Claus-Peter Herold; Stephan Von Tapavicza; Michael Neuss; Wolfgang Zöllner; Frank Burbach
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1989-03-08
Filing date: 1990-03-01
Publication date: 1991-12-27
Also published as: IE900803L; IE63532B1; JPH04503966A; BR9007191A; EP0386636A1; NO913240D0; EP0386636B2; DE59000441D1; JP2834320B2; US5403822A; WO1990010681A1; MX173267B; CA2047706C; EP0386636B1; NO913240L; ES2052997T3; AU626118B2; GR3026139T3; AU5180290A; DK0386636T3

Abstract

L'invention décrit l'utilisation d'esters sélectionnés, fluides à la température ambiante et présentant des points d'éclair supérieurs à 80°C, d'acides monocarboxyliques d'origine synthétique et/ou naturelle comportant 6 à 11 atomes de C et d'alcools monofonctionnels et/ou polyfonctionnels en tant que phase huile ou constituants de la phase huile de boues de forage inverses convenant pour la prospection off-shore écologique de gisements de pétrole ou de gaz naturel. Ces esters contiennent, dans une phase huile fermée, une phase aqueuse dispersée ainsi que des émulsifiants, des charges, des additifs contre les pertes de fluide et, si cela se révèle souhaitable, d'autres additifs courants. Dans une autre version, l'invention concerne des fluides de forage inverses, du type indiqué, caractérisés par le fait que la phase huile contient des esters d'acides monocarboxyliques d'origine synthétique et/ou naturelle comportant 6 à 11 atomes de C avec des alcools monofonctionnels et/ou polyfonctionnels mélangés, si cela se révèle souhaitable, à d'autres éléments appartenant à la catégorie des composés ne présentant pas de risques pour l'environnement.The invention describes the use of selected esters, fluid at room temperature and having flash points above 80 ° C., monocarboxylic acids of synthetic and / or natural origin containing 6 to 11 C atoms and monofunctional and / or polyfunctional alcohols as the oil phase or constituents of the oil phase of reverse drilling muds suitable for off-shore ecological prospecting of petroleum or natural gas deposits. These esters contain, in a closed oil phase, a dispersed aqueous phase as well as emulsifiers, fillers, additives against fluid losses and, if this proves desirable, other common additives. In another version, the invention relates to reverse drilling fluids, of the type indicated, characterized in that the oil phase contains esters of monocarboxylic acids of synthetic and / or natural origin containing 6 to 11 C atoms with monofunctional and / or polyfunctional alcohols mixed, if this proves desirable, with other elements belonging to the category of compounds presenting no risk to the environment.

Description

Invert drilling muds

The invention describes new drilling fluids based on ester oils and invert drilling muds based thereon, which are characterized by high ecological compatibility and, at the same time, good standing and usage properties. An important area of application for the new drilling fluid systems is in offshore drilling for the exploitation of oil and / or natural gas, with the invention in particular aiming to provide technically usable drilling fluids with high ecological compatibility. The use of the new drilling fluid systems is particularly important in the marine area, but is not limited to this. The new flushing systems can also be used in general for land-based drilling, for example for geothermal drilling, for water drilling, for performing geoscientific drilling and for drilling in the mining sector. In principle, it also applies here that the ecotoxic problem area is substantially simplified by the ester-based drilling oil fluids selected according to the invention.

Oil-based drilling fluids are generally used as so-called invert emulsion slurries, which consist of a three-phase system: oil, water and finely divided solids. These are preparations of the type of W / O emulsions, i.e. H . the aqueous phase is heterogeneously finely dispersed in the closed oil phase. A plurality of additives, in particular emulsifiers, are provided to stabilize the overall system and to set the desired performance properties or Emu Igatorsy systems, weighting agents, fluid loss additives, alkali reserves, viscosity regulators and the like. For details, reference is made, for example, to the publication P. A. Boyd et al. "New Base Oil Used in Low-Toxicity Oil Muds" Journal of Petroleum Technology, 1985, 137 to 142 and R. B. Bennett "New Drilling Fluid Technology - Mineral Oi l Mud" Journal of Petroleum Technology, 1984, 975 to 981 and the literature cited therein.

The relevant technology has for some time recognized the importance of ester-based oil phases to reduce the problems caused by such oil rinses. For example, US Pat. Nos. 4,374,737 and 4,481,121 describe oil-based drilling fluids in which nonpolluting oi is to be used. Aromatic mineral oil fractions and vegetable oils of the type peanut oil, soybean oil, linseed oil, corn oil, rice oil or also oils of animal origin such as whale oil are mentioned as nonpolluting oils side by side and of equal value. All of the ester oils of plant and animal origin mentioned here are triglycerides of natural fatty acids which are known to have a high level of environmental compatibility and are clearly superior to hydrocarbon fractions - even if they are free from aromatics - for ecological reasons.

Interestingly, however, no example of the above-mentioned US patents describes the use of such natural ester oils in invert drilling fluids of the type concerned here. Mineral oil fractions are used throughout as a closed oil phase. Oils of plant and / or animal origin are out of the question for practical reasons. The theological properties of such oil phases cannot be mastered for the wide temperature range of 0 to 5 C required on the one hand and up to 250 C and above on the other hand. In practice, ester oils of the type concerned do not behave in the same way as the mineral oil fractions based on pure hydrocarbons used to date. In practice, ester oils are also subject to partial hydrolysis, especially in W / Overt invert drilling muds. In this way free carboxylic acids are formed. The older applications P 38 42 659.5 and P 38 42 703.6 (D 8523 "Use of selected ester oils in drilling fluids (I)" and D 8524 "Use of selected ester oils in drilling fluids (II)") describe the problems triggered thereby and give suggestions their solution.

The subject of these earlier applications is the use of ester oils based on selected monocarboxylic acids or. Monocarboxylic acid mixtures and monofunctional alcohols with at least 2, preferably with at least 4, carbon atoms. The older applications show that with the esters or ester mixtures of monofunctional reactants disclosed there, not only can satisfactory theological properties be set in the fresh drilling fluid, but that it is also possible to work with and use selected known alkali reserves in the drilling fluid Way to retain undesired corrosion. The addition of lime (calcium hydroxide or l ime) and / or the concomitant use of zinc oxide or comparable zinc compounds is provided as the alkali reserve. However, an additional restriction is advisable. If the undesired thickening of the oil-based invert rinsing system is to be prevented in practical operation, the amount of the alkalizing additive and in particular the amount of lime must be limited. According to the disclosure of the older applications mentioned, the maximum amount envisaged is about 2 Ib / bbl oil rinse. The teaching of the invention described in the following extends the circle of ester oils which can advantageously be used in the W / O rinsing sludges concerned here.

Accordingly, the invention relates, in a first embodiment, to the use of esters of monocarboxylic acids of synthetic and / or natural origin with 6 to 11 carbon atoms and 1- and / or polyfunctional alcohols which are flowable at room temperature and have flash points above 80 ° C. fetch as oil phase or part of the oil phase from invert drilling muds, which are used for an environmentally friendly development of petroleum or. Natural gas deposits are suitable and, in a closed oil phase, a disperse aqueous phase together with emulsifiers. . Containing weighting agents, fluid-ioss additives and, if desired, other conventional additives.

In a further embodiment, the invention describes invert drilling fluids of the type described, which are characterized in that the oil phase is flowable at room temperature and has flash points above 80 ° C. from synthetic and / or natural monocarboxylic acids having 6 to 11 carbon atoms and Contains 1- and / or polyfunctional alcohols, if desired also in a mixture with other components from the class of ecologically compatible compounds (non-polluting oil).

Alcohol components are preferably used in the ester oils defined in this way, which are ecologically and toxicologically harmless even after a partial ester cleavage in practical use. In particular, the invention takes into account the inhalation-toxicological problem in this aspect when dealing with oil rinsing in practice Use can be significant. In the following, the ester oils used according to the invention are first described in more detail; the following subchapters deal with possible mixture components and further details on the invention.

The ester oils used according to the invention

The ester oils described according to the invention are based on the carboxylic acid side of synthetic and / or natural monocarboxylic acids having 6 to 11 carbon atoms, which can be straight-chain and / or branched. Straight - chain and usually even - numbered carboxylic acids in this range are derived in particular from oils or. Fats of natural origin and, as is known, form the so-called lead fatty acids in the range C _fi _ _{1 f} .. Synthetic carboxylic acids of this type are also easily accessible, for example, by oxidation of Ziegler alcohols. Branched or mixtures of branched and straight-chain carboxylic acids in the area affected here are available from numerous petrochemical processes.

Preferred esters of these medium chain length carboxylic acids with 1- and / or polyfunctional alcohols are flowable and pumpable for the intended use according to the invention even in the temperature range from 0 to 5 ° C. In particular, monocarboxylic acid esters of the specified type or their mixtures with ecologically compatible components - the so-called nonpolluting oils - which have a Brookfield (RVT) viscosity in the temperature range from 0 to 5 ° C. not above 50 mPas are used as the oil phase and preferably not be above 40 mPas. Particularly suitable are esters or ester mixtures of the type indicated, the viscosity of which is at most about 30 mPas. The esters of the type mentioned, which are preferably used in the drilling mud, furthermore show solidification values (pour point and pour point) below 0 ° C., corresponding limit values below -5 ° C. and in particular below -10 ° C. being particularly suitable. Particularly for reasons of operational safety, flash points that are as high as possible are still desirable, so that corresponding values of at least 90 ° C. and preferably above 100 ° C. are particularly expedient. A suitable choice of the ester-forming components enables the person skilled in the art to achieve the desired combination of substance properties for the ester oils concerned in a manner known per se.

The carboxylic acid esters of medium chain length used in the carboxylic acid unit according to the invention can be divided into two subclasses: in esters of these acids with monofunctional alcohols and in esters of these acids with polyfunctional alcohols. The following information applies to the selection of particularly suitable components.

Esters of the specified type based on monofunctional alcohols preferably contain at least 6 and more preferably at least 7 carbon atoms in the alcohol component. This comparatively high lower limit for the alcohol component makes it possible to ensure that in practical use, even after a partial ester cleavage, toxicological and in particular inhalation-toxicological problems can be overcome with simple means. In practical use, it can be assumed that the at least slightly warmed rinsing is pumped around and, in particular, is freed of the drilled hole by sieving. As aging progresses and the partial hydrolysis triggered thereby, problems arise not only from the formation of free fatty acids or their salts as described in the earlier applications D 8523 and D 8524 mentioned, but also the alcohol component released Difficulties for practical operation mean. This alcohol content will always have to be taken into account if, due to its volatility and the specified working temperatures, a nuisance caused by alcohol vapors is to be expected. Lower monofunctional alcohols can create additional problems here which, although they can be overcome — for example in a constructive manner — are eliminated from the outset in the preferred embodiment of the invention. If monofunctional alcohols of natural and / or synthetic origin are present in the ester oils used according to the invention and are predominantly aliphatically saturated, preference is given to those alcohols in the range from C _R _ -. _ used for ester formation. Its vapor pressure is so low under the working conditions that occur in practice that the last problem area addressed here is eliminated.

However, esters of monofunctional alcohols are not restricted to this C number range. Higher monofunctional alcohols may also be considered, the esters of which, with the medium chain length carboxylic acids according to the invention, provide theologically useful oils or oil components. In particular, 1 - and / or polyolefinically unsaturated alcohols, which can have up to 24 carbon atoms or even higher carbon numbers, come into consideration here. Alcohols of this type are accessible in particular by selective reduction of corresponding natural fatty acids, which will be discussed in the context of further aspects of the description of the invention.

Inhalation-toxicological problems are generally insignificant from the outset when using esters of polyfunctional alcohols. Suitable polyfunctional alcohols are, in particular, di- to tetravalent alcohols, and here in particular the corresponding lower representatives of this class of substances with preferably 2 to 6 carbon atoms. Particularly suitable multifunctional le Alcohols are the glycol and / or the propanediols. Accordingly, ethylene glycol, 1, 2-propanediol and / or 1, 3-propanediol are particularly preferred alcohol components for the formation of the ester oils described according to the invention. Both partial esters and full esters of the type concerned here can be considered, the full esterified products being particularly important for rheological reasons. It can be symmetrical and / or asymmetrical esters or. Act ester mixtures if at least some of the carboxylic acids in the specified C number range are also used.

The oil phase of the W / O emulsions can be formed exclusively from esters of the type described here, but the mixture components specified below can also be used together with these ester oils defined according to the invention.

Mix components in the oil phase

Oil components suitable for blending with the monocarboxylic acid esters of the invention are the mineral oils used in the practice of drilling fluids today, and preferably essentially aromatic-free aliphatic and / or cycloaliphatic hydrocarbon fractions of the required flow properties. Reference is made to the relevant state of the art in print and the commercial products on the market.

However, particularly important mixture components in the sense of the action according to the invention are environmentally compatible ester oils, such as those in particular in the older applications mentioned. , , (D 8523 and D 8524) are described. To complete the disclosure of the invention, essential characteristics of such esters or. Ester mixtures briefly summarized. In a first embodiment, flowable and pumpable esters of monofunctional alcohols with 2 to 12, in particular with 6 to 12 C atoms and aliphatic saturated monocarboxylic acids with 12 to 16 C atoms or a mixture thereof are used in the temperature range from 0 to 5 C. at most approximately equal amounts of other monocarboxylic acids are used as the oil phase. Preference is given to ester oils which are at least about 60% by weight, based on the respective carboxylic acid mixture, of esters of aliphatic C.- ₁ . Monocarboxylic acids and, if desired, the rest to minor amounts of shorter-chain aliphatic and / or longer-chain, then in particular 1 - and / or polyolefinically unsaturated monocarboxylic acids decrease. Esters are preferably used which have a Brookfield (RVT) viscosity in the temperature range from 0 to 5 ° C. in the range not above 50 mPas, preferably not above 40 mPas and in particular of at most about 30 mPas. The esters used in the drilling mud show solidification values (pour point and pour point) below - 10 C, preferably below - 15 C and in particular have flash points above 100 C, preferably above 150 ° C. The in the ester or. Carboxylic acids present in an ester mixture are straight-chain and / or branched and are of vegetable and / or synthetic origin. They can be derived from appropriate triglycerides such as coconut oil, palm kernel oil and / or babassu oil. The alcohol residues of the esters used are derived in particular from straight-chain and / or branched saturated alcohols having preferably 6 to 10 carbon atoms. These alcohol components can also be of vegetable and / or animal origin and have been obtained by reductive hydrogenation of corresponding carboxylic acid esters.

Another class of particularly suitable ester oils is derived from olefinically 1- and / or polyunsaturated monocarboxylic acids having 16 to 24 carbon atoms or their mixtures with subordinate amounts of other, in particular saturated, monocarboxylic acids and monofunctional alcohols with preferably 6 to 12 carbon atoms. These ester oils are also flowable and pumpable in the temperature range from 0 to 5 ° C. Particularly suitable are esters of this type which are derived from more than 70% by weight, preferably more than 80% by weight and in particular more than 90% by weight of olefinically unsaturated carboxylic acids in the range from C 1 to _C 4 .

I o— 4

Here, too, the solidification values (pour point and pour point) are below - 10 C, preferably below - 15 ° C, while the flash points are above 100 C and preferably above 160 ° C. The esters used in the drilling mud show a Brookfield (RVT) viscosity of not more than 55 mPas, preferably not more than 45 mPas, in the temperature range from 0 to 5 C.

In the case of ester oils of the type concerned here, two subclasses can be defined. In the first, the unsaturated C _{1 6} __ "- monocarboxylic acid residues present in the ester are not more than 35% by weight. -% of 2- and poly-olefinically unsaturated acids, preferably at least about 60 wt. -% of the acid residues are simply olefinically unsaturated. In the second embodiment, those present in the ester mixture are derived

C, _c -. "-Monocarboxylic acids to more than 45 wt. %, preferably 1 oz *, of more than 55% by weight of 2- and / or polyolefinically unsaturated acids. Saturated carboxylic acids in the range C _{1 g} , _{1 g} present in the ester mixture advantageously make up no more than about 20% by weight and in particular no more than about 10% by weight. Saturated carboxylic acid esters, however, are preferably in the range of lower C numbers for the acid residues. The present carboxylic acid residues can be of vegetable and / or animal origin. Vegetable starting materials are, for example, palm oil, peanut oil, castor oil and in particular turnip oil. Carboxylic acids of animal origin are, in particular, corresponding mixtures of fish oils such as herring oil. Another interesting class of ester oils that can be used as a mixture component in the context of the inventive action is in the parallel application. , , (D 8606 "Use of selected ester oils of lower carboxylic acids in drilling fluids"). These are esters of C, _ς -monocarboxylic acids and mono- and / or polyfunctional alcohols which are flowable at room temperature and have flash points above 80 C, and which are preferably also flowable and pumpable in the temperature range from 0 to 5 C. Corresponding esters of these lower carboxylic acids with monofunctional alcohols with at least 8 C atoms and / or esters of these acids with dihydric to tetravalent alcohols with preferably 2 to 6 C atoms are particularly suitable. For practical reasons, acetic acid is particularly suitable as the ester-forming acid component of this class. Measures for rheology and volatility or. The solidification values of preferred esters of this subclass correspond to the values mentioned above and can be found in detail in the parallel patent application mentioned, to which express reference is made here for the purpose of the invention disclosure.

Suitable mixture components from this subclass are, in particular, esters of monofunctional alcohols of natural and / or synthetic origin, the chain length of which is predominantly aliphatically saturated alcohols in the range of C.sub.1. ,. , in the case of 1 - and polyolefinically unsaturated o - 1 D

Alcohols, but also at higher C numbers, for example up to about C. "

Multi-component mixtures fall within the scope of the invention which, together with the ester oils defined according to the invention and based on medium-chain carboxylic acids, can contain one or more of the mixture components listed in detail here. Basically, any mixes can be used insofar as they meet the basic theological requirements for invert drilling fluids of the type concerned here. Examples of such multi-component mixtures include materials based on different types of ester oils or mixtures of substances additionally containing mineral oil. • ^•

The mixing ratios in the oil phase

The esters defined according to the invention from monocarboxylic acids of synthetic and / or natural origin with 6 to 11 carbon atoms and 1 - and / or polyfunctional alcohols are present as an at least substantial component in the oil phase, their proportion generally being at least about 20 to 25% by weight. -% of the oil phase. In important embodiments, at least about a third of the oil phase is formed by ester oils of this type; particularly important embodiments of the invention are characterized in that esters of the type described here form the predominant part of the closed oil phase.

Already in the earlier application P 38 42 703.6 (D 8524) mentioned at the beginning, reference is made to the fact that, in particular when using saturated fatty acids of natural origin, limited amounts of esters of the so-called preliminary fatty acids - ie. H . of the range of C _{c 1 n} - can also be used. Acting

However, as a rule, these are comparatively small amounts which, depending on the origin of these saturated fatty acid mixtures, make up at most about 15% by weight. The teaching of the present invention therefore also leads to the extent of the details of the earlier application mentioned out.

Other mixing components of the invert drilling fluid

I consider all common mixture components for conditioning and for the practical use of the inverter. Drilling muds, as they are used according to current practice with mineral oils as a closed oil phase. In addition to the disperse aqueous phase, emulsifiers, weighting agents, fluid loss additives, viscosity formers and alkali reserves are particularly suitable here.

In a particularly important embodiment of the invention, use is also made here of the further development of such invert drilling fluids based on ester oil, which are the subject of the earlier application. . . (D 8543 "Olephile basic amine compounds as an additive in invert drilling muds") by the applicant.

The teaching of this earlier application is based on the concept of using an additional additive in invert drilling fluids based on ester oils, which is suitable for keeping the desired theological data of the drilling fluid in the required range even when increasingly large amounts of free ones are in use Carboxylic acids are formed by partial ester hydrolysis. These released carboxylic acids should not only be captured in a harmless form, it should also be possible, if desired, to convert these free carboxylic acids into valuable components with stabilizing or. convert emulsifying properties for the overall system. According to this teaching, the use of basic amine compounds which are capable of salt formation with carboxylic acids and has a pronounced oieophilic nature and at most limited water solubility as an additive in the oil phase is provided. The oleophilic amine compounds can at the same time be used at least in part as the alkali reserve of the invert drilling fluid, but they can also be used in combination with conventional alkali reserves, in particular together with lime. Preferred is the use of oleophilic amine compounds which are at least predominantly free of aromatic ingredients. Particularly suitable are optionally olefinically unsaturated aliphatic, cycloaliphatic and / or heterocyclic oleophilic basic amine compounds which contain one or more N groups which are capable of salt formation with carboxylic acids. In a preferred embodiment, the water solubility at room temperature of these amine compounds is at most about 5% by weight. -% and is expediently less than 1 wt.

Typical examples of such amine compounds are at least largely water-insoluble primary, secondary and / or tertiary amines, which can also be alkoxyated to a limited extent and / or substituted with, in particular, hydroxyl groups. Further examples are corresponding aminoamides and / or heterocycles containing nitrogen as a ring component. Suitable are, for example, basic amine compounds which have at least one long-chain hydrocarbon radical with preferably 8 to 36 carbon atoms, in particular with 10 to 24 carbon atoms, which can also be mono- or poly-olefinically unsaturated. The oleophilic basic amine compounds can be added to the drilling fluid in amounts up to about 10 Ib / bbI, preferably in amounts up to about 5 Ib / bbI and in particular in the range from about 0.1 to 2 Ib / bbI.

It has been shown that the concomitant use of such oleophilic basic amine compounds can effectively prevent thickening of the rinsing system, which presumably can be attributed to a disturbance in the W / O inverting system and can be attributed to the formation of free carboxylic acids by ester hydrolysis.

In a preferred embodiment of the action according to the invention, care is taken not to use any significant amounts of strongly hydrophilic bases of an inorganic and / or organic type in the oil rinse. In particular, the invention dispenses with the use of alkali metal hydroxides or highly hydrophilic amines of the diethanolamine and / or triethanolamine type. Lime can be used effectively as an alkali reserve. However, it is then expedient to limit the maximum amount of lime to be used with about 2 lb / bbI, it being preferred to work with drilling mud loads on lime that are slightly below this, for example in the range from about 1 to 1.8 Ib / bbI (lime / drilling fluid). In addition to or instead of the lime, other known alkali reserves can be used. Particularly noteworthy here are the less basic metal oxides of the zinc oxide type. Even when such acid scavengers are used, however, care will be taken not to use too large amounts in order to prevent undesired premature aging of the drilling fluid - combined with an increase in viscosity and thus a deterioration in the theological properties. The peculiarity of the inventive action discussed here prevents the formation of undesirable amounts of highly effective O / W emulsifiers, or at least restricts them so that the good rheological values are maintained for a sufficiently long time even during thermal aging in operation.

The following also applies:

Invert drilling muds of the type concerned here usually contain, together with the closed oil phase, the finely disperse aqueous phase in amounts of about 5 to 45% by weight and preferably in amounts of about 5 to 25% by weight. The range from about 10 to 25% by weight of disperse aqueous phase can be of particular importance.

The following rheological data apply to the rheology of preferred invert drilling fluids in the sense of the invention: Plastic viscosity (PV) in the range from about 10 to 60 mPas, preferably from about 15 to 40 mPas, yield point (YP) in the range

2 from about 5 to 40 lb / 100 ft, preferably from about 10 to 25

Ib / 100 ft - each determined at 50 ° C. For the determination of these parameters, for the measurement methods used and for the otherwise usual composition of the invert drilling fluids described here, the details of the prior art, which were cited at the beginning and are described in detail, for example, in the manual "Manual" apply Of Drilling Fluids Technology "from NL-Baroid, London, GB, there in particular under" Mud Testing - Tools and Techniques "and" Oil Mud Technology ", which is freely accessible to interested professionals. In summary, the following can be said here for the purpose of completing the disclosure of the invention:

Emulsifiers that can be used in practice are systems that are suitable for forming the required W / O emulsions. Selected oleophilic fatty acid salts, for example those based on amidoamine compounds, are particularly suitable. Examples of this are described in the already cited US Pat. Nos. 4,374,737 and the literature cited therein. A particularly suitable type of emulsifier is the product sold by NL Baroid under the trade name "EZ-mul".

Emulators of the type concerned here are sold commercially as highly concentrated active ingredient preparations and can be used, for example, in amounts of about 2.5 to 5% by weight, in particular in amounts of about 3 to 4% by weight, based in each case on the ester oil phase - Find use.

In practice, hydrophobicized lignite is used in particular as a fluid loss additive and thus in particular to form a dense covering of the drilling walls with a largely liquid-impermeable film. Suitable amounts are for example in the range from about 15 to 20 Ib / bbI or in the range from about 5 to 7 wt. -I - based on the ester oil phase.

In drilling fluids of the type concerned here, the viscosity former commonly used is a cationically modified, finely divided bentonite which can be used in particular in amounts of about 8 to 10 lb / bbI or in the range of about 2 to 4% by weight, based on the ester oil phase . The weighting agent usually used in the relevant practice for setting the required pressure equalization is barite, the additional amounts of which are adapted to the respectively expected conditions of the bore. For example, by adding barite it is possible to increase the specific weight of the drilling fluid to values in the range up to approximately 2.5 and preferably in the range from approximately 1.3 to 1.6.

The disperse aqueous phase is loaded with soluble salts in invert drilling fluids of the type concerned here. Calcium chloride and / or potassium chloride are predominantly used here, the saturation of the aqueous phase at room temperature with the soluble salt being preferred.

The previously mentioned emulsifiers or. Emulsifier systems may also serve to improve the oil wettability of the inorganic weighting materials. In addition to the aminoamides already mentioned, further examples are alkylbenzenesulfonates and imidazoline compounds. Additional information on the relevant prior art can be found in the following references: GB 2 158 437, EP 229 912 and DE 32 47 123.

In addition to the advantages already described, the drilling fluids based on the use of ester oils of the type described are also characterized by a significantly improved lubricity. This is particularly important if the passage of the drill pipe, and thus also the borehole, deviate from the vertical in bores, for example at greater depths. The rotating drill pipe easily comes into contact with the borehole wall and digs into it during operation. Ester oils of the type used as the oil phase according to the invention have a significantly better lubricating effect than the mineral oils previously used. Here is another important advantage for the action according to the invention.

B e i s p i e l e

In the following examples, invert drilling fluids are produced in a conventional manner using the following frame recipe: 230 ml of ester oil and 26 ml of water

6 g organophilic bentonite (Geltone II from NL Baroid)

12 g organophilic lignite (Duratone from NL Baroid) x g lime (x = 1 or 2)

6 g W / O emulsifier (EZ-mul NT from NL Baroid)

346 g barite

9.2 g CaCI ₂ x 2 H ₂ 0

In this recipe, approximately 1.35 g of lime correspond to the value of 2 Ib / bbI.

After a W / O invert drilling fluid has been put together in a manner known per se from the components used, varying the ester oil phase, the viscosity parameters are first determined on the unaged and then on the aged material as follows:

Measurement of viscosity at 50 C in a Fann 35 viscometer from NL Baroid. The plastic viscosity (PV), the yield point (YP) and. Are determined in a manner known per se

2 the gel strength (lb / 100 ft) after 10 see. and 10 min.

The aging takes place by treatment in an autoclave - in the so-called roller oven - for a period of 16 hours at 125 ° C. example 1

The reaction product of isononanoic acid and isoheptanol - an ester with a flash point of 145 ° C and a pour point below - 10 ° - is used as the ester oil. The amount of lime in the framework recipe given at the beginning is 2 g in this experiment.

The key figures determined on the unaged and on the aged material are listed in the following table. unaged aged

Material material

Plastic viscosity (PV) 26 31

Yield point (YP) 14 14

Gel strength (lb / 100 ft ² )

10 lake. 5 6

10 min. 8 9

Example 2

The approach of Example 1 is repeated, but the amount of lime used in the frame formulation is now 1 g. The key figures determined on the unaged and aged material are as follows.

unaged aged

Material material

Plastic viscosity (PV) 28 31

Yield point (YP) 8 8

Gel strength (lb / 100 ft ² )

10 see. 5 5

10 min. 7 7

Example 3

In Examples 3 and 4 below, the ester oil used is the esterification product of 2-ethylhexanol and C _fi _ .. - preliminary fatty acids (commercial product "Edenor" from the applicant). The ester oil has a flash point of around 151 C and a pour point below - 10 C.

The table below summarizes the viscosity values on the unaged and aged material, which were determined when 2 g of lime were added to the frame formulation. unaged aged

Material material

Plastic viscosity (PV) 28 33

Yield point (YP) 7 12

Gel strength (lb / 100 ft ² )

10 lake. 5 6

10 min. 8 16 Example 4

The approach of Example 3 is repeated, but lime is now only added to the esterol rinse in an amount of 1 g. The viscosity values determined on the unaged and aged material are as follows. unaged aged

Material material

Plastic viscosity (PV) 24 23

Yield point (YP) 12 12

Gel strength (lb / 100 ft ² )

10 lake. 5

10 min. 7

Example 5

The ester oil from Examples 1 and 2 - ester from isononanoic acid / - isoheptanol - is in a further ester rinse with an oil / water ratio of 80/20 with the simultaneous addition of 2 g of a strongly oleophilic amine (hand ice product "Araphen G2D" from the applicant - the reaction product of an epoxidized C. _, _a alpha-OIefins and diethanolamine) is used in the following Rah¬ menrezeptur: 210 ml Esteröl 48.2 g water

6 g organophilic bentonite (omnigel)

13 g organophilic lignite (Düratone from NL Baroid) g lime

8 g W / O emulsifier (EZ-mul NT from NL Baroid)

270 g barite

20 g CaCI. x 2 H ₂ 0

The viscosity values determined on the unaged and aged material are summarized in the table below. unaged aged

Material material

Plastic viscosity (PV) 35 32

Yield point (YP) 31 20

Gel strength (lb / 1 _0 ft ² )

10 lake. 12 7

10 min. 14 9

Examples 6 to 9

In the general formulation of Examples 1 and 2 - using lime in the amount of 1 g as in Example 2 - the following four esters are used as the oil phase and theologically determined according to the information in Examples 1 and 2 before and after aging :

Example 6: Ester from 2-ethylhexanol and C ₈ acid, flash point 152 ° C, viscosity at 20 ° C 4 to 5 mPas, at 50 ° C 2 to 3 mPas, pour point below 10 ^υ C,

Example 7: Ester from 2-ethylhexanol and C. acid with a flash point of 166 ° C, viscosity at 20 ° C 4 to 5 mPas, at 50 ° C 2 to 3 mPas, pour point approx. -10 ° C.

Example 8: (melderin commercial product "Lorol" the An¬) ester of n-octanol and C _{1f-carboxylic} acid. (Commercial product "Edenor" of the applicant) having a flash point of 171 C, viscosity at 20 ° C for 6 mPas, at 50 ° C 3 mPas and a pour point of

+ 3 ° C.

Example 9: Ester from isononanoic acid and n-octanol (commercial product "Lorol" from the applicant). The rheological data determined before and after aging are as follows:

Example 6 unaged aged

Material material

Plastic viscosity (PV) 21 22

Yield point (YP) 15 1 1

Gel strength (lb / 100 ft ² )

10 lake. 6 8

10 min. 8 5

Example 7 Unaged Aged

Material material

Plastic viscosity (PV) 29 31

Yield point (YP) 8 8

Gel strength (lb / 100 ft ² )

10 lake. 5 5

10 min. 7 7

Example 8 Unaged Aged

Material material

Plastic viscosity (PV) 26 28

Yield point (YP) - 17 14

Gel strength (lb / 100 ft ² )

10 lake. 6 4

10 min. 8 7 Example 9 Unaged Aged

Material material

Plastic viscosity (PV) 27 29

Yield point (YP) 12 13

Gel strength (lb / 100 ft ² )

10 lake. 5 4

10 min. 7 7

Examples 10 and 11

Two further ester oils are worked up as part of the basic formulation of Example 1 (2 g of lime) for drilling fluids of the type mentioned. Your basic rheological data are determined before aging and after aging at 16 hours in a roller oven at 125 ° C.

Example 10

Ester oil from C _{0 /} . Preflow fatty acids (commercial product "V85KR" from the applicant) and isotridecyl alcohol, flash point 183 C, pour point below - 10 C.

unaged aged

Material material

Plastic viscosity (PV) 44 55

Yield point (YP) 13 24

Gel strength (lb / 100 ft ² )

10 lake. 6 7

10 min. 8 10 Example 1 1

Ester oil based on the C _{0 / ι n} pre-fatty acids and 2-ethylhexanol mentioned in Example 10 with the flash point of 151 C and a pour point below - 10 C.

unaged aged

Material material

Plastic viscosity (PV) 24 35

Yield point (YP) 1 0 15

Gel strength (lb / 100 ft ² )

10 lake. 5 5

10 min. 7 14

Example 12

In a further series of experiments, a strongly oleophilic amine (commercial product "Araphen G2D" from the applicant) is added to an ester oil according to Example 11 as an anti-aging agent in an amount of 2 g. The aging in the roller oven at 125 ° C is now extended to the period of 72 hours. The rheological data determined on the unaged and aged material are as follows.

unaged aged

Material material

Plastic viscosity (PV) 24 24

Yield point (YP) 8 1 4

Gel strength (lb / 100 ft ² )

10 lake. 4 5

10 min. 6 7 In the same way, the recipe of Example 10 is mixed with the specified anti-aging agent in the stated amount and the oil rinse based on this mixture is aged in a roller oven at 125 ° C. for 72 hours. The rheological data determined before aging and after aging are the following.

unaged aged

Material material

Plastic viscosity (PV) 43 66

Yield point (YP) 1 4 24

Gel strength (lb / 100 ft ² )

10 see. 7 9

10 min. 9 1 3

Claims

Patent claims

1. Use of esters which are flowable at room temperature and have flash points above 80 C from monocarboxylic acids of synthetic and / or natural origin with 6 to 11 C atoms and 1- and / or polyfunctional alcohols as the oil phase or part of the oil phase of are suitable invert drilling muds, which Ssung for an environmentally friendly Erschlie¬ of oil and gas sources and included in a closed oil phase a disperse aqueous phase together with emulsifiers, weighting agents, fluid loss additives and, if desired, further customary ^'additives.

2. Embodiment according to claim 1, characterized in that esters or ester mixtures are used which are flowable and pumpable even in the temperature range from 0 to 5 C.

3. Embodiment according to claims 1 and 2, characterized ge indicates that monocarboxylic acid esters of the specified type or their mixtures with ecologically compatible components (nonpolluting oils) are used as the ol phase, a Brookfield (RVT) viscosity in the temperature range from 0 to 5 C. not above 50 mPas, preferably not above 40 mPas and at most of about 30 mPas.

4. Embodiment according to claims 1 to 3, characterized gekenn¬ characterized in that the esters of carboxylic acids with 6 to 11 carbon atoms used in the drilling mud solidification values (pour point and pour point) below 0 C, preferably below - 5 ° C and in particular below - 10 C and there Have flash points of at least 90 ° C, preferably above 100 ° C.

5. Embodiment according to claims 1 to 4, characterized gekenn¬ characterized in that such alcohol components are used in the ester oils that are harmless even after a partial ester cleavage in practical use - ecologically and toxicologically - here in particular inhalation-toxicologically.

6. Embodiment according to claims 1 to 5, characterized gekenn¬ characterized in that carboxylic acid esters with at least 7, preferably with at least 8 carbon atoms containing monofunctional ien alcohols and / or esters of polyhydric, in particular 2 to 6 carbon atoms containing alcohols become .

7. Embodiment according to claims 1 to 6, characterized gekenn¬ characterized in that one works with esters of monofunctional alcohols of natural and / or synthetic origin, the chain length in the presence of predominantly aliphatic saturated alcohols in the range of C__ _{- £} . , in the case of mono- and / or polyolefinically unsaturated alcohols but also at higher C numbers, for example up to C_ _ü .

8. Embodiment according to claims 1 to 7, characterized gekenn¬ characterized in that those of glycol and / or a propanediol are used as esters of polyhydric alcohols.

9. Embodiment according to claims 1 to 8, characterized gekenn¬ characterized in that the mixture components from the class of nonpolluting oi ls ester oils from monofunctional alcohols having 2 to 12, preferably 6 to 10 carbon atoms and olefinically 1- and / or polyunsaturated monocarboxylic acids with 16 up to 24 C-atoms are used, which preferably already have solidification values (pour point and pour point) below - 10 C, preferably below - 15 ° C and flash points above 100 ° C.

10. Embodiment according to claim 9, characterized in that olefinically unsaturated carboxylic acid esters are used as the mixture component, which are more than 70% by weight, preferably more than 80% by weight and in particular more than 90% by weight. % of olefinically unsaturated

Derive carboxylic acids in the range of C, _c _., And thereby

1 b - have a Brookfield (RVT) viscosity of not more than 55 mPas, preferably not more than 45 mPas, in particular in the temperature range from 0 to 5 ° C.

1 1. Embodiment according to claims 9 and 10, characterized in that the esters of unsaturated monocarboxylic acids used as mixture components do not form more than 35% by weight. % of 2- and poly-olefinically unsaturated acids which are at least about 60% by weight 1-fold olefinically unsaturated and / or more than 45% by weight, preferably more than 55% by weight. - Derive% of 2- and / or multiply olefinically unsaturated acids.

12. Embodiment according to claims 1 to 8, characterized in that esters of aliphatically saturated monocarboxylic acids with 1 to 5 carbon atoms and / or esters of aliphatic saturated monocarboxylic acids with 12 to 16 carbon atoms are used as mixture components based on esters, which in turn are preferably pumpable and flowable in the range from 0 to 5 ° C. and are ecologically and toxicologically safe in use even after partial hydrolysis.

3. Embodiment according to claims 1 to 12, characterized ge indicates that the carboxylic acid esters in invert drilling mud are used together with alkali reserves, lime being a particularly preferred alkali reserve, but optionally in addition to or instead of lime, limited amounts of metal oxides of Type of zinc oxide or related zinc compounds are available.

14. Embodiment according to claims 1 to 13, characterized ge indicates that in the drilling fluid the use of substantial amounts of strong hydrophilic bases such as alkali metal hydroxide and / or diethanolamine is dispensed with and any lime additive present is expedient to the maximum amount of about 2 Ib / bbI Oil flushing is limited.

1 5th embodiment according to claims 1 to 14, characterized ge indicates that the carboxylic acid esters in the invert drilling muds are used together with amine compounds capable of salt formation with free carboxylic acids, of a pronounced oleophilic nature and at most limited water solubility.

1 6th embodiment according to claims 1 to 1 5, characterized ge indicates that the esters are used in drilling fluids, the finely disperse aqueous phase in amounts of about 5 to 45 in invert drilling mud together with the closed oil phase based on ester % By weight, preferably in amounts of about 5 to 25% by weight.

17. Invert drilling fluids, which for an environmentally friendly tapping of petroleum or. Natural gas deposits are suitable and in a closed oil phase a disperse aqueous phase together with emulsifiers, weighting agents, contain fluid-loss additives and, if desired, other customary additives, characterized in that the oil phase is flowable at room temperature and has flash points above 80 C esters of monocarboxylic acids of synthetic and / or natural origin with 6 to 11 C atoms and 1 - and / or multifunctional Contains alcohols, if desired in admixture with other components from the class of ecologically compatible compounds (nonpolluting oils).

18. Invert drilling fluid according to claim 17, characterized gekenn¬ characterized in that it is alkaline conditioned, preferably as alkali reserve lime and / or metal oxides of the type of zinc oxide are present.

19. Invert drilling fluid according to claims 17 and 18, characterized in that no substantial amounts of strongly hydrophilic bases such as alkali metal hydroxides or highly hydrophilic amines such as diethanolamine are present in the oil flushing and that when alkali is added this alkali reserve amounts of about 2 Ib / bbI (lime / Oil rinse).

20. I nvert drilling mud according to claims 17 to 19, characterized in that they contain amine compounds capable of salt formation with carboxylic acids of pronounced oleophilic nature and at most limited water solubility.

21. Invert drilling fluid according to claims 17 to 20, characterized in that it has a plastic viscosity (PV) in the

Range of about 10 to 60 mPas and a yield point (yield

2 point YP) in the range of about 5 to 40 lb / 100 ft - each determined at 50 C -.

22. Invert drilling fluid according to claims 17 to 21, characterized ge indicates that the esters of monocarboxylic acids with 6 to 11 carbon atoms at least about 25 wt .-%, preferably at least about a third and in particular the predominant Make up part of the closed oil phase.

23. I nvert drilling fluid according to claims 17 to 22, characterized in that its disperse water content makes up about 5 to 45% by weight, preferably about 10 to 25% by weight, and in particular salts of the type CaC and / or KCI contains ent dissolved.

24. I nvert drilling fluid according to claims 17 to 23, characterized ge indicates 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 has.