NO302127B1 - Use of surfactant ester sulfonate salts in water- and oil-based drilling muds and other borehole treatment agents, as well as the sludge thus obtained - Google Patents

Description

The present invention relates to the use of selected emulsifiers with increased ecological acceptability for the production of pourable, dispersed systems which are either available as water-in-oil invert emulsions with a continuous oil phase or as aqueous emulsions with a dispersed oil phase, and which are suitable for technical use within the framework of pourable borehole treatment agents. As a characteristic example of means of this kind, the invention is described below using oil-based or water-based drilling fluids and drilling mud built up on these. However, the scope of application for the invention's design of auxiliary liquids of the type described here is not limited thereto. In particular, areas such as "spotting fluids", "spacers", auxiliary fluids for processing and stimulation as well as for fracturing are also taken into consideration.

The invention also relates to invert drilling mud obtained by means of the emulsifiers described above.

The invention is based on the task of influencing the ecological acceptability of these currently widely used aids by means of selected and particularly ecologically acceptable emulsifier types. In its preferred embodiment, the invention uses these biologically acceptable emulsifiers together with oil phases with improved environmental friendliness and particularly biodegradability.

In the area of liquid flushing systems in connection with the lowering of drilling in rock and the simultaneous collection of released cuttings, the so-called invert drilling muds are today of great importance, muds which, on the basis of water/oil emulsions, contain a dispersed aqueous phase in the continuous oil phase. The content of dispersed aqueous phase is usually in the range of approx. 5 to 50 weight-56.

Also known are water-based drilling muds with an emulsified, dispersed oil phase (oil-in-water type) whose oil content can range from a few percent to approx. 50 weight #. Water-in-water emulsion sludge of this type exhibits a number of significant advantages compared to pure water-based sludge types.

To stabilize the dispersion form chosen in each case, one needs, depending on the application, corresponding emulsifiers either of the water-in-oil type (invert sludge) or of the oil-in-water type (emulsion sludge). When it comes to available literature, reference should be made, for example, to G.R. Gray, H.C.E. Darley, "Composition in Properties of Oil Well Drilling Fluids", 4th edition, Gulf Publishing Co., Houston London, 1981, especially pages 51, 64 and 320 ff.

01jefås in drilling mud of the type described here and comparably structured other borehole treatment agents are formed in practice today, so to speak, exclusively with the help of mineral oil fractions. However, this causes a not inconsiderable burden on the environment when, for example, drilling mud is brought immediately or via drilled cuttings to the surrounding environment. Mineral oils are difficult and anaerobically practically not degradable and must therefore be considered a long-term pollutant. Although these oil phases as the main component or at least a significant proportion of the drilling mud are an important point for the ecological considerations, the other components in such multi-substance mixtures must also be given some attention. The emulsifiers are of particular importance here. By definition, compounds of this type are very effective even in very low concentration and, as is known, they are capable of intense interaction with the vegetable or animal organism.

The present invention is based on the task of improving the work tools of the described type on the basis of continuous or dispersed oil phases mixed with aqueous phases, taking into account the ecological acceptability in a significant way in relation to the usual work tools of this type. The invention thereby proposes, particularly for the area of application in question here, emulsifiers or emulsifier components which are in and of themselves known and thereby described as being substantially environmentally friendly, but which have so far not found any application in the area of work described here.

In the preferred embodiment of the invention, these environmentally friendly emulsifiers of the water-in-oil type or of the oil-in-water type are used together with oil/water phases where the oil phases, in turn, have improved ecological acceptability and which can in particular be broken down by means of natural decomposition mechanisms in an environmentally friendly way.

In order to solve this first partial task, the invention proposes, as ecologically acceptable or problem-free compounds with emulsifying action, in using per se known surface-active ester sulfonate salts of the type described below, a type which, as is known, depending on constitution and interaction with the surrounding system, is to classify as water-in-oil emulsifiers or as oil-in-water emulsifiers.

As mentioned in the introduction, the invention relates to the use of surface-active salts of esters which are internally sulphonated and which exhibit at least predominantly organically bound sulphur, where the esters are of mono- and/or polyvalent olefinically unsaturated carboxylic acids with at least 8 C atoms, preferably of unsaturated carboxylic acids of natural and/or synthetic origin with 10 to 40 C atoms, preferably from the range<C>12-32°^especially the range ci0_24'whereby in particular also mixtures of different carboxylic acid residues can be present in the ester sulphonate salt, and lower mono- and/or polyvalent alcohols, preferably of from 1- to 4-valent alcohols with preferably up to 5 C atoms, in particular of 1- to 3-valent alcohols with up to 3 C atoms, (ester sulfonate salts), as ecologically acceptable water-in-oil emulsifiers -type or the oil-in-water type in pourable and pumpable drilling fluids or other pourable borehole treatment agents which, together with an aqueous phase, exhibit a continuous or dispersed pea oil phase and which is suitable for the environmentally friendly utilization of biological deposits, in particular petroleum-respectively natural gas deposits.

As indicated above, the present invention relates to an invert drilling mud which is suitable for the environmentally friendly utilization of geological deposits and which in a continuous oil phase contains a dispersed aqueous phase together with emulsifiers and usual additional auxiliary substances, for example thickeners, liquid loss additives, weighting agents, water-soluble salts and alkali reserves, and this drilling mud is characterized by the fact that, together with an ecologically acceptable, continuous oil phase, it contains surface-active ester sulphonate salts of the kind specified in claim 1 as an emulsifier or as an emulsifier component.

Of particular importance in this context is corresponding invert drilling mud which in a continuous oil phase contains a dispersed aqueous phase together with emulsifiers, common additional auxiliaries such as thickeners, fluid loss additives, weighting agents, soluble salts and/or alkali reserves. According to the invention, this task is solved by using selected surface-active ester sulfonate salts as an emulsifier or at least as an essential component of an ecologically acceptable emulsifier system.

These emulsifiers are therefore preferably used on the basis of surface-active ester sulfonate salts together with environmentally friendly ester oils, oleophilic alcohols and/or corresponding ethers as continuous or dispersed oil phase. Special reference must be made here to the inventors' own technical development, which is described in a large number of older patents and patent publications with a view to proposals for replacing today's common mineral oil fractions with ecologically acceptable, easily degradable oil phases. Thereby, different types of replacement oils are described which can also be used in a mixture with each other. This refers to selected, oleophilic monocarboxylic acid esters, selected polycarboxylic acid esters, to at least largely water-insoluble and pourable alcohols under the working conditions, to the corresponding ethers and to selected carbonic acid esters. In summary, reference should be made to the older publications NO 171.562-B with department, NO 171.601-B with department, NO 171.501-B with department, NO 171.502-B with department, NO 179.487-B, NO 178.403-B, NO 300.043-B1 , NO 171.561-B with department, NO 178.933-B and to NO 178.868-B. All the older publications mentioned here concern the area of oil-based drilling muds, particularly of the water/oil invert type. Water-based emulsion sludges using these oil phases with increased degradability are described in the older publications NO P914110, NO P913658, NO P914111 as well as in the already mentioned publications P924224 and NO P924345.

In its most important embodiment, the invention comprises the joint use of the above-mentioned emulsifiers from the class of surface-active ester sulfonate salts together with dispersed or continuous oil phases of the latter type. When it comes to details, reference should be made to the previously mentioned applications.

The sulfuration of unsaturated carboxylic acids of natural or synthetic origin as well as their esters with mono- and/or polyfunctional alcohols has long been known. Hereby, the general term "sulfurization" in precise chemical definition includes the reaction that takes place or the reaction products formed according to two different possibilities which can also occur next to each other.

The first of these possibilities is described in the chemical definition as sulphation where sulfuric acid ester groups are formed which contain sulfur bound to carbon over an oxygen atom. These sulphation products occur, for example, by addition of the sulfuric acid residue on the olefinic double bond to unsaturated carboxylic acid molecules or by esterification of free hydroxyl groups present on the C skeleton.

Sulfonation is different from this. Characteristic of this reaction is the binding of organically bound sulfur to the C-skeleton during the formation of immediate C-S bonds. The teaching of the invention deals with emulsifiers of the type described which are at least predominantly true sulphonates as just described, i.e. with immediately organically bound sulfur in the molecule.

Despite these constitutionally clear differences that also differ in chemical behavior, for example when it comes to the hydrolysis stability of the compound classes in question, the language used in practice is unclear. The literature frequently talks about sulphonates when in reality it is about sulphates. Thus, for example, we are talking about sulfonation products that are relatively weakly resistant to acids and alkalis, as, next to real sulfonic acids, unstable sulfuric acid esters are formed above all, reference should be made here, for example, to DE 12 46 717 and the summary presentation by E.L. Sanders "Sulfoils - The Resurgent Surfactants", "Soap/Cosmetrics/Chemical Specialties", May 1975, 39/40. Also in the area of the present invention, namely drilling flushing systems and in particular the so-called invert mud, linguistically imprecise definitions are often chosen, here, for example, reference should be made to US-PS 3 642 623, column 6, lines 26 to 28. The production of real sulphonates with predominantly organically bound sulfur of esters of unsaturated carboxylic acids, in particular corresponding unsaturated fatty acids with mono- and/or polyhydric alcohols have been known for a long time. Here, for example, reference should be made to the already mentioned DE 12 46 717 and DE-A 1 34 37 443. Thus, for example, from unsaturated oils of natural and thereby vegetable and/or animal origin, genuine sulfonates can be obtained under comparatively mild working conditions when highly diluted sulfur trioxide/air mixtures are used for sulphurisation. Upon subsequent neutralization, highly electrolysis-resistant water-soluble compounds are obtained which are described as storage-resistant, acid- and alkali-resistant emulsifiers. Technical areas of application are, for example, the production of leather fattening agents, melting agents for the textile industry, the production of metalworking oils and the production of electrolyte-resistant emulsions for various areas of application. When it comes to details, reference should be made to the already mentioned literature. Ester sulfonates within the definition of the invention and in particular their combination with ecologically acceptable oil phases with increased degradability have so far not been proposed for the work area aimed at according to the present invention, namely borehole treatment agents.

The class of so-called fatty acid sulphonates of the importance mentioned at the outset plays an absolutely significant role as emulsifier components in the build-up of oil-in-water and water-in-oil emulsions for the area of drilling fluids and drilling treatment agents, both in practice and in the literature. Here, however, only the corresponding sulphurisation products of unsaturated carboxylic acids are primarily described, but not their esters within the definition of the invention. In addition to this, sulphonates of a different constitution play a significant role where, in particular, the sulpho grouping is introduced via aromatic molecular constituents in the emulsifier molecule. Connections of this type do not agree with the objective of the invention with a view to increased ecological acceptability. From the voluminous printed prior art, reference should be made, for example, to DE 12 45 289 as well as US 3 476 912, 4 012 329, 3 899 431, 3 340 188, 3 878 111 and the already mentioned 3 642 623. In these publications, among other mentioned petroleum sulphonates, tall oil bex sulphonates, combinations of sodium oleic sulphonate and titanates as well as further combination systems.

In the area of particularly water-based flushing systems and comparable liquid phases, the so-called Turkish red oil plays a significant role as an emulsifier component. This is, as is known, a sulfated oil based on castor oil, see in this connection "Rompp Chemie-Lexikon", 7th edition

(19744) 3707.

In contrast, the teaching of the invention aims at the use of surface-active salts of internal sulphonated esters which exhibit at least predominantly organically bound sulphur, formed from mono- and/or polyhydric, olefinically unsaturated carboxylic acids with at least 8 C atoms and lower mono- and/or polyhydric alcohols, as ecologically acceptable emulsifiers of the water-in-oil type or oil-in-water type. In contrast to the salts of unsaturated carboxylic acids sulphonated in a similar way internally and during the formation of C-S bonds respectively their salts, the substance class proposed by the invention is distinguished by the additional ester bond and thereby by the alcohol residue bound in the molecule. The free carboxylic acid group is thereby exempted from immediate salt formation. At the same time, the constantly present alcohol residue enables a very extensive variation of the base molecule. In connection with the possibility of the targeted control of the degree of sulfonation, which will be described in more detail below, there is thereby an opportunity for the synthesis of emulsifier molecules with a possible wide distribution of the ratios between lipophilic and hydrophilic material properties. In connection with further options for variation discussed in more detail below, there is also the possibility of a targeted technically improved way of working without having to renounce the ecological advantages of the emulsifier class described here. The teachings of the invention thereby enable, for example, the permanent stabilization of oil-based water-in-oil invert emulsions, while at the same time renouncing the widely used N-containing emulsifier systems whose compatibility is not unthinkable precisely in the particularly sensitive marine eco systems.

The ester sulfonate salts preferred for the purposes of the invention are derived from unsaturated monocarboxylic acids of natural and/or synthetic origin with 10 to 40 C atoms and preferably from the range c^ 2—32'

Reasonable starting materials available in large quantities can be the corresponding fatty acid glycerol esters of natural origin. The predominant proportion of the carboxylic acid residues present here lies in the range of the corresponding fatty acids with 16 to 24 C atoms and 1 to 5 double bonds. Examples of such ester oils of natural origin are fatty acid glycerol esters and in particular the corresponding triglycerides based on coriander, chauimogra sunflower seed, cottonseed, olive, peanut, linseed, lard, meadow foam, lard and fish oil. The new beet oil rich in oleic acid is of particular importance as a material used for the production of the sulphonated fatty acid esters used according to the invention. In this way, you can use specially selected triglycerides, but also any mixtures of different origins. Mixtures of natural and synthetic esters are also possible.

The term fatty acid glycerol ester thereby includes mono-, di- and triesters as well as mixtures thereof as they can be obtained by production by esterification of 1 mol of glycerol with 1 to 3 mol of fatty acid or fatty acid mixture or by transesterification of unsaturated triglycerides with especially 0.3 to 2 mol of glycerol. The term unsaturated fatty acid ester or the sulphonates obtained therefrom expressly also includes such native and/or synthetic esters or ester mixtures whose fatty acid components are not completely, but only partially, made up of unsaturated fatty acids. Also covered is the area of mixtures, especially the technical mixtures formed in practice of various unsaturated or largely unsaturated fatty acid glycerol esters among themselves. In all these cases, it is preferred that the proportion of the mono- and/or polyunsaturated carboxylic acids in the ester or the ester mixture at least amounts to approx. 5 mol-#, calculated on the carboxylic acid mixture. The co-use of saturated fatty acids in subordinate or at most quantitative proportions is expressly covered by the teachings of the invention.

Ester-forming alcohol components include in particular the residues of 1- to 4-hydric alcohols with preferably up to 5 C atoms. Important esters can thereby be derived correspondingly from methanol or ethanol, but preferably also higher alcohols. Thus, when using sulfonated esters of monofunctional alcohols, for the reasons discussed in more detail below, it may be appropriate to use sufficiently low-volatile alcohol components, as a potential ester cleavage in use does not trigger any inhalation toxicity risk due to the released alcohols . This, discussed in more detail below in connection with ester oils based on monofunctional alcohols, point of view, however, has less importance in connection with the emulsifiers. These emulsifier components are therefore only used in comparatively limited amounts so that the corresponding risks are of correspondingly minor importance. However, the possible inhalation toxicity risk does not exist when using esters based on polyfunctional alcohols due to their low volatility. This means that diols such as ethylene glycol, 1,2- or 1,3-propanediol or equivalent butanediols are taken into account. Also of particular importance is the already mentioned glycerol as an ester-forming polyfunctional alcohol component.

Especially when it comes to esters based on multifunctional alcohols, there is an opportunity to modify only one or more or all of the carboxylic acid residues present on the alcohol molecule by introducing the sulfo group. In a manner known in and of itself, the hydrophilic structural character is more strongly accentuated, the greater the number of sulfonate groups selected per ester molecule. This must be taken into account in particular when using esters of polyunsaturated carboxylic acids which are in principle available for a multiple sulphonation reaction.

In this context, according to the invention, it is preferred to use ester sulfonate salts with a molar ratio of sulfonate: carboxylic acid residues of a maximum of 1 (statistical mean value). However, it may therefore also be preferred to use lower values for this molar ratio. In the indicated manner, the lipophilic part of the ester molecule is then enhanced. This can be used for targeted development of particularly suitable water-in-oil emulsifiers. Thus, for example, the molar ratio of sulfonate:carboxylic acid residue can lie in the range 0.25 to 0.7. In the case of ester sulfonate salts based on triglyceride, the preferred molar ratios of the type in question lie in the range of approx. 0.3 to 1 (statistical mean value), i.e. in the range of approx. one sulfonate group per molecule and up to a degree of conversion that allows a sulfonate group on each carboxylic acid residue.

The production of the invention's particularly important substance group ester sulfonate salts on the basis of unsaturated mono-, di- and/or triglycerides which are derived from fatty acids with 16 to 24 C atoms and one to five double bonds with a proportion of unsaturated fatty acids of more than 50% by weight , 1 is an improved embodiment in detail subject of the older DE publication P 39 36 001.6. When it comes to details, particular reference is made to this. Ester sulfonates of this type can, in a preferred embodiment, derive more than 50% by weight from oleic acid and linoleic acid and go back in particular to beet oil rich in oleic acid.

In the manner described in the older publication, reference should also be made here to J. Falbe (ed) "Surfactants in Consumer Products", Springer Verlag, Berlin-Heidelberg, 1987, page 61, a largely selective introduction of sulfonate groups succeeds under retraction of the partially always co-occurring introduction of sulfate groups into the ester molecule. The preferred emulsifiers of the invention based on ester sulphonate salt have a ratio of sulphonate:sulphate groups of at least 60:40. Higher sulfonation values, especially those above 70:30, are preferred. In the practice of the technical method, by using the described ester oils, without unreasonable technical effort, ratios of sulphonate:sulphate groups in the range 75:25 to 85:15 can be achieved. Ester sulphonates of this type constitute particularly suitable materials for the large-scale technical application within the framework of the invention.

An important possibility for modifying the emulsifier properties and particularly for influencing the HLB value (hypophilic-lipophilic balance) for the ester sulphonate salts in question lies in the choice of the salt-forming cations. With the help of this, in particular, the water and oil solubility can also be affected. In general, it applies that water-soluble salts of monovalent cations, especially alkali metal and/or ammonium salts, lead to favoring the hydrophilic property image, while the use of multivalent cations can reduce water solubility. In compounds of this type, the lipophilic character can prevail so that compounds of this type are particularly suitable for use in the area of water-in-oil invert emulsions. Multivalent cations derive in particular from the alkaline earth metals and aluminium. In this class of multivalent cations, the element calcium is particularly important, but sodium and ammonium are predominantly important when it comes to the monovalent cations. It can be seen that the structure of the selected ester sulfonate salts of the invention exhibits a number of parameters that can be directly influenced, which enables control of the emulsifier effect and thereby an optimization of the desired effect. Ester sulfonate salts within the framework of the invention are particularly in this respect far more flexibly modifiable than the corresponding sulfonate salts of internally sulfonated, unsaturated monocarboxylic acids of natural and/or synthetic origin.

In practical use, there is thereby the further possibility of in situ formation of such ester sulphonate salts of polyvalent cations. The following examples should make this clear: The aqueous dispersed phase in oil-based drilling muds of the invert type is generally filled with dissolved salts in practical use, particularly calcium salts such as calcium chloride. If such aqueous phases containing dissolved alkaline earth metal salts are used in the build-up of the invert emulsions, the corresponding alkaline earth metal salts of the ester sulphonates occur by in situ precipitation also when these emulsifier components are first used in the form of their sodium salts. In this way, it is possible not only with a special economic realization of the teachings of the invention, it has been shown that by such in situ formation of the alkaline earth metal salts particularly effective as water-in-oil emulsifiers, rheologically highly stable invert emulsions are available. Precisely in the case of such a salt exchange reaction described here, it is clearly shown that the potassium salts can also have a special significance as a material of use: during the resalting in the last described sense, calcium salts that act as water-in-oil emulsifiers are also formed potassium chloride which passes into the aqueous dispersed phase and here acts as a preferred component for inhibiting water-swellable clays within the framework of the utilization of geological deposits.

The ester sulfonate salt-based emulsifiers are used in a preferred embodiment as the essential emulsion-type-forming and emulsion-stabilizing components. However, the teaching of the invention also covers mixing systems where the ether sulphonates are used together with other emulsifier components. Preferably, these other emulsifier components are in turn ecologically acceptable, in this context reference should be made to NO P922717 where selected ether-based emulsifiers are described for oil-based inversion emulsions. Other examples of suitable co-emulsifiers are described in NO 178,582-B and NO 178,581-B described surfactant α-sulfo fatty acid disalts and alkylglycoside compounds.

Particularly suitable co-emulsifiers can also be salts, in particular corresponding alkali or alkaline earth metal salts, of sulphonated and/or non-sulphonated, unsaturated and/or saturated fatty acids of natural and/or synthetic origin. The invention thus includes the mixing of any fatty acids or fatty acid salts as co-emulsifiers to the present active ingredient mixtures, whereby in particular the co-use of unsaturated, straight-chain and/or branched fatty acids proves to be particularly problem-free.

If such emulsifier mixtures are used, the preferred embodiments of the invention constitute the ester sulfonate salts at least approx. 10 weight # and preferably at least approx. 50 wt-# of the relevant emulsifier system.

The ester sulphonate salts are used in amounts from approx. 0.1 to 10 wt-5é, calculated on the sum of the liquid phases water and oil. Preferred amounts are in the range of approx. 0.5 to 5 weight-# of the emulsifier components whereby the range from approx. 1 to 3 weight # of the emulsifier, always calculated on the sum of water and oil, is of particular importance.

An important relief for the economic production of the emulsifiers of the invention lies in the fact that the bleaching of the primarily formed reaction products can be dispensed with, which according to the known written technique for the production of this emulsifier class is considered an essential procedural step. The production method for active substance mixtures containing ester sulphonate salts within the framework of the invention can accordingly be limited to the method steps sulphonation and salt formation. The reaction raw product can be added immediately before the technical utilization.

In the particularly preferred embodiment mentioned at the outset, the relevant oil phases are formed by the ecologically acceptable ester oils, oleophilic alcohols and/or ethers described in the aforementioned older publications. Using these agents, the invention relates to pourable and pumpable borehole treatment agents in the temperature range from 5 to 20°C, in particular drilling mud based on

either a continuous oil phase, especially in mixture with a

dispersed aqueous phase (water-in-oil invert type), or a dispersed oil phase in a continuous aqueous phase

(the oil-in-water emulsion type).

With regard to their possible physical properties, the ecologically acceptable oil and oil phases cover a wide area. The invention includes, on the one hand, the oil phase which is pourable and pumpable even at low temperatures. Here are particularly representatives that are suitable for the production of water-in-oil emulsions. But also highly viscous to solid oil phases or substances of this type can also be used within the scope of the invention. The following considerations provide examples of this: For water-based oil-in-water emulsion muds, a high mobility of the dispersed oil phase is not necessary, and sometimes not even desired. For example, comparatively viscous, adjusted oil phases can be advantageous for ensuring good lubrication properties. Another possibility for the use of highly viscous or even solid ecologically acceptable oil phases is provided when the relevant oil phases in each case in the finished product only partially consist of these highly viscous to solid representatives of degradable esters, alcohols and/or ethers which in turn are mixed with comparatively thin oils of this type.

Generally speaking, for all oil phases or oil mixture phases to be used according to the invention, the flash points are at least approx. 100°C and preferably at least approx. 135°C, for safety reasons. Values that are clearly above this, especially those above 150°C, can be particularly appropriate. In general, it also applies to the different potential hydrolysis-exposed oil phases that can be used within the scope of the invention, that the requirement for ecological acceptability does not apply only to the application compound, i.e. for example the ester oil or mixture of ester oils chosen in each case, but also applies that with a partial saponification in practical use no toxicological and especially inhalation toxicological risks arise. It is described in detail within the framework of the above-mentioned older applications that this particularly applies to the various representatives of the ester oils, whereby here also monofunctional alcohols from the ester formation have a particular importance. Monofunctional alcohols are, compared to polyfunctional alcohols, highly volatile when it comes to the lowest parts, so that a secondary risk can arise in the case of partial hydrolysis here. Preferably, according to the class of the different ester oils, co-used monofunctional alcohols or corresponding residues of these alcohols are selected in such a way that they have at least 6 C atoms in the molecule and preferably at least 8 C atoms.

For invert drilling mud of the type of the invention, it applies, regardless of the specific nature of the closed oil phase, that in preferred embodiments they exhibit a plastic viscosity, PV, in the range 10 to 60 mPas, and a yield point (Yield Point or YP) in the range 5 to 40 lb/100 ft<2> (conversion factor: 1 lb/100 ft<2>= 2.0885 Pa), all determined at 50°C.

As ecologically acceptable and at low temperatures well pourable oil phase, especially ester oils of monocarboxylic acids have been shown to be, especially when in a preferred embodiment of the invention they originate from at least one of the following subclasses: a) Ester of C^_g- monocarboxylic acids and mono- and/or polyfunctional alcohols whereby the residues of monohydric alcohols exhibit at least 6 and preferably at least 8 C atoms and the polyhydric alcohols preferably have 2 to 6 C atoms in the molecule,

b) Esters of monocarboxylic acids of synthetic and/or natural origin with 6 to 16 C atoms, especially esters

of corresponding aliphatic, saturated monocarboxylic acids and mono- and/or polyfunctional alcohols of the type mentioned under a),

c) esters of olefinic mono- and/or polyunsaturated dicarboxylic acids with at least 16 and especially 16 to 24 C atoms

and especially monofunctional straight and/or branched alcohols.

Starting materials for the production of numerous monocarboxylic acids within this subclass, especially with higher carbon numbers, are vegetable and/or animal oils. Mention should be made of coconut oil, palm kernel oil and/or babassu oil, in particular as starting materials for obtaining monocarboxylic acids in the predominant range up to C-^g, and with essentially saturated components. Vegetable ester oils, especially for olefinically mono- and possibly polyunsaturated carboxylic acids in the area, are for example palm, peanut, castor, sunflower seed and especially beet oil. However, synthetically obtained components are also important structural elements for ecologically acceptable oil phases, both on the carboxylic acid and alcohol side.

Invert drilling mud usually contains, together with the continuous oil phase, the finely dispersed aqueous phase in amounts of approx. 5 to 50 weight #. In water-based emulsion slurries, the dispersed oil phase is usually present in amounts of at least approx. 1 to 2 weight #, frequent in quantities of at least approx. 5 weight-# at an upper limit of the oil proportion of approx. 40 to 50 weight-#, the weight-# being always calculated on the sum of the non-gravity liquid part oil/water.

In addition to the water content, all additives usable for comparable sludge types are taken into account. These additives can be water-soluble, oil-soluble and/or water-respectively oil-dispersible.

Common additives are besides the invention's defined emulsifiers, for example liquid loss additives, structure-viscosity-building soluble and/or insoluble substances, alkali reserves, agents for inhibiting the unwanted exchange of water between drilled formations, for example water-swellable clays and/or salt layers, and the for example water-based flushing fluid, cross-linking agents for better attraction of emulsified oil phase on solid surfaces, for example to improve the lubrication effect, but also to improve the oleophilic closure of exposed rock formations, for example rock surfaces, biocides, for example to inhibit bacterial attack on oil-in -water emulsions and the like. In detail, reference should be made here to the available literature as it is described in the specialist literature indicated at the outset in a comprehensive manner, reference should be made, for example, to the above-mentioned Gray and Darley, chapter 11, "Drilling Fluid Components". As an extract to be obtained here: Finely dispersed additives to increase the mud density: Barium sulphate (baryte) is widely used, but calcium carbonate (calcite) or the mixed carbonate of calcium and magnesium (dolomite) are also used.

Agents for building up the structural viscosity which at the same time also act as a liquid loss additive: Bentonite or hydrophobic bentonite should be mentioned first. For saltwater mud, other comparable clays, particularly attapulgite and sepiolite, can be of practical importance.

The co-use of organic polymer compounds of natural and/or synthetic origin can also be of great importance in this context. Particular mention should be made of starch and chemically modified starch, cellulose derivatives such as carboxymethyl cellulose, guar gum, xanthan gum or also pure, synthetic, water-soluble and/or water-dispersible polymer compounds, especially of the type of high molecular weight polyacrylamide compounds with or without anionic or cationic modifications.

Thinners for viscosity regulation: The so-called thinners can be organic or inorganic in nature. Examples of organic diluents are tannins and/or qebracho extract. Further examples are lignite and lignite derivatives, especially lignosulfonates. As already stated, in a preferred embodiment of the invention, the co-use of toxic components is waived, whereby the corresponding salts with toxic heavy metals such as chromium and/or copper should be mentioned in the first line. An example of inorganic diluents are polyphosphate compounds.

Additives that inhibit the unwanted water exchange with, for example, clays: The additives known from the prior art in connection with water-based drilling mud are taken into account here. In particular, it concerns halides and/or carbonates of alkali and/or alkaline earth metals, whereby corresponding potassium salts, possibly in combination with lime, can be particularly important.

Here, for example, reference should be made to the corresponding publications in "Petroleum Engineer International", September 1987, pages 32-40 and to "World Oil", November 1983, pages 93-97.

Alkali reserves: Here, the inorganic and/or organic bases matched to the overall behavior of the sludge are taken into account, in particular corresponding basic salts or hydroxides of alkali and/or alkaline earth metals as well as organic bases. The type and amount of these basic components are selected and adjusted thereby in a manner known per se so that the borehole treatment agent is set to a pH value in the range of approx. neutral to medium alkaline, especially in the area approx. 7.5 to 11.

The quantity of the auxiliaries and additives used in each case is in principle within the usual limits and can therefore be found in the already indicated literature.

The invention shall be illustrated in more detail with reference to the following examples.

EXAMPLES

In the following examples 1 and 2, drilling flushing systems are put together in compliance with a standard recipe for oil-based drilling muds of the water-in-oil type. whereby the closed oil phase is formed by a selected oleophilic carboxylic acid ester according to the following definition;

Ester mixture of essentially saturated fatty acids based on palm kernel and 3-ethylhexanol which predominantly reverts to C12^14 fatty acids and which corresponds to the following specification:

Cg: 3.5 to 4.5 wt-#

C10: 3.5 to 4.5 wt-56

C12: 65 to 70 wt-#

C14: 20 to 24 weight #

<C>]^: approx. 2 weight #

C18: 0.3 to 1 wt #.

The ester mixture is present as a pale yellow liquid with a flash point above 165°C and a Brookfield viscosity at 20°C of 7 to 9 cP.

Determination of characteristic viscosity values is carried out on unaged and aged material: Measurement of the viscosity at 50°C in a Fann-35 viscometer from the company Baroid Drilling Fluids Inc. The plastic viscosity (PV) is determined in a manner known per se. the yield strength (YP), as well as the gel strength (lb/100 ft<2>with conversion factor 1 lb/100 ft<2>= 2.0885 Pa) after 10 seconds and after 10 minutes. The liquid loss value (HTEP) in examples 1 and 2 is also determined.

The aging of the drilling mud in question is carried out by treatment for a period of 16 hours at 125°C in an autoclave, in a so-called "Roller oven", roller oven.

The drilling mud systems are put together according to the following basic recipe in a manner known per se:

230 ml carboxylic acid ester oil

26 ml of water

6 g organophilic bentonite (Geitone from the company Baroid Drilling Fluids Inc.) 12 g organophilic lignite (Duratone from the company Baroid Drilling Fluids Inc.)

2 g lime

12 g emulsifier on an ester sulphonate basis

346 g baryte

9.2 g of CaCl 2 x 2 H 2 O

Example 1

An unsaturated C12_<g>4<-t>riglyceride on a beet oil basis is reacted with gaseous SO3 (approx. 5 wt-# SO3 in nitrogen or air) in the temperature range 70 to 80° C under an application molar ratio of triglyceride esters:SO3= 1:1.2. An aqueous alkaline hydrolysis is then carried out to a constant pH value. The products are then adjusted to a pH value of 6.5 to 8.5. An aqueous concentrate of the low-sulfonated beet oil ester with the following characteristic values is obtained: Active substance 39.7 weight-#; unsaturated proportion 27.1 wt-#; water 58.9 wt-#; Na 2 SO 4 1.4 wt-£.

This reaction mixture is used as an "Emulsifier based on esersulfonate salt" in the above-mentioned basic recipe.

The characteristics determined on non-aged and aged material, as stated above, are summarized in the tabular summary given below:

HTHP 6 ml

Example 2

A beet oil sulphonate is used as an emulsifier, which is, however, somewhat more sulphonated. In detail, the following information applies here for the sulfonation step: Triglyceride-ester ratio: SO3 = 1:3; Process temperature 80 to 90°C.

The aqueous sulphonate salt product which is used as "Emulsifier" within the framework of the initially stated basic recipe, has the following characteristics: Active ingredient 53.9 weight-$6; content of unsaturated material 15.6 wt-#; water 44.4 wt-#; Na 2 SO 4 1.7 wt #.

The values determined on unaged and aged material are as follows:

HTHP 18 ml

Examples 3 and 4

Using the ester sulfonate salt-based emulsifiers from examples 1 and 2, water-in-oil invert drilling systems are assembled on the basis of the pure mineral oils common in practice (commercial product BP 83 HF) according to the following recipe, known in and of itself manner:

204 ml mineral oil

7.2 g emulsifier based on ester sulphonate salt

3.6 g of calcium

6 g of organophilic lignite (Duratone from the company Baroid Drilling

Fluids Inc.)

3.6 g co-emulsifier based on C^g fatty acid

105.6 g aqueous fatty acid chloride solution (9.2 g CaCl2x 2H20)

4.8 g of organophilic bentonite (Geitone from the company Baroid Drilling Fluids Inc.)

216 g baryte

In example 3, the comparatively weaker sulphonated emulsifier based on beetroot oil according to example 1 is used, example 4 uses the correspondingly stronger sulphonated emulsifier based on beetroot oil according to example 2.

The characteristic values determined on non-aged and aged flushing systems are as follows:

Example 3

HTHP 7 ml Example 4

HTHP 6 ml

The values determined on unaged and aged material are as follows:

Example 5

In the following example 5, a water-based emulsion slurry is prepared using a complex oleophilic polycarboxylic acid ester with lubricant character as a dispersed oil phase, according to the following working recipe: First, a 6-weight homogenized bentonite slurry is prepared using commercial bentonite (not hydrophobic) with tap water while adjusting to a pH value of 9.2 to 9.3 using caustic soda.

Starting from this swollen aqueous bentonite phase, the individual components of the water-based ester oil emulsions are incorporated, all the time under intense mixing:

350 g 6 weight-^-ig bentonite solution

1.5 g technical carboxymethyl cellulose, low viscosity

(Relatin U 300 S 9)

35 g of sodium chloride

70 g complex ester

6 g emulsifier from example 2

219 g baryte.

As oleophilic ester oil phase, the reaction product of trimethylolpropane (14 wt-#), a commercial dimer-fatty acid mixture (24 wt-#) and the remainder oleic acid is used. The dimer fatty acid mixture contains 77 wt-# dimer acids and the rest are tri- and higher polycarboxylic acids, here is the wt-#, calculated for the dimer fatty acid mixture.

Viscosity determinations are carried out on the thus produced oil-in-water emulsion sludge as follows: First, at room temperature, the plastic viscosity (PV), yield strength (YP) and gel strength are determined after 10 seconds and after 10 minutes, on the non-aged feed - the rial.

The emulsion sludge is then aged for 16 hours at 90°C under static conditions to test the influence of temperature on the emulsion stability. The viscosity ■values are then determined as at room temperature.

The results were:

Claims (20)

1. Use of surface-active salts of esters which are internally sulphonated and which exhibit at least predominantly organically bound sulphur, where the esters are of mono- and/or polyvalent olefinically unsaturated carboxylic acids with at least 8 C atoms, preferably of unsaturated carboxylic acids of natural and/or synthetic origin with 10 to 40 C atoms, preferably from the range ^ 12— 32 °^ especially the range ci( 3— 2^' whereby in particular also mixtures of different carboxylic acid residues can be present in the ester sulphonate salt, and lower mono- and/or polyhydric alcohols, preferably of from 1- to 4-valent alcohols with preferably up to 5 C atoms, in particular of 1- to 3-valent alcohols with up to 3 C atoms, (ester sulfonate salts), as ecologically acceptable emulsifiers of the water-in-oil type respectively the oil-in-water type in pourable and pumpable drilling fluids or other pourable borehole treatment agents which, together with an aqueous phase, exhibit a continuous or dispersed oil phase and which are suitable for environmental friendly utilization of biological deposits, especially oil and natural gas deposits. 2. Use according to claim 1, at least partially of ester sulphonate salts of internally sulphurised mono-, di- and/or triglycerides of natural and/or synthetic origin. 3. Use according to claims 1 and 2 of ester sulfonate salts whose carboxylic acid residues partly also revert to saturated carboxylic acids, whereby preferably the mono- and/or polyvalent unsaturated carboxylic acids constitute at least 50 mol-#, calculated on the carboxylic acid mixture. 4. Use according to claims 1 to 3 of ester sulphonate salts of mono-, di- and/or especially triglycerides of natural origin, preferably on the basis of vegetable and/or animal oils. 5. Use according to one of claims 1 to 4 of ester sulfonate salts with a molar ratio of sulfonate:carboxylic acid residue of max. 1 (statistical mean value), whereby also lower values, for example 0.25 to 0.7 may be preferred for this molar ratio and in the case of ester sulfonate salts based on triglyceride, lie within the range 0.3 to 1. 6. Use according to claims 1 to 5 of ester sulfonate salts on a triglyceride basis where the ratio of sulfonate:sulfate groups is at least 60:40 and is preferably 70:30 and particularly in the range 75:25 to 85:15. 7. Use according to claims 1 to 6 of ester sulfonate salts based on unsaturated mono-, di- and triglycerides as well as mixtures thereof which are derived from fatty acids with 16 to 24 C atoms and 1 to 5 double bonds with a proportion of unsaturated fatty acids of more than 50 wt. #, whereby ester sulfonate salts may be preferred if the fatty acid component(s) is derived in an amount of more than 50 wt-# from oleic acid and/or linoleic acid and which in particular reverts to beet oil rich in oleic acid. 8. Use according to claims 1 to 7 of water- and/or oil-soluble ester sulfonate salts of alkali metals, alkaline earth metals and/or ammonium, whereby the use of corresponding sodium, calcium and/or magnesium salts is preferred and the calcium salt is preferably used in the production and stabilization of water -in-oil emulsions. 9. Use according to claims 1 to 8 where the ester sulfonate salts make up at least the predominant emulsifier proportion, but can however also be used together with other, particularly biologically acceptable water-in-oil or oil-in-water emulsifiers whereby in particular the corresponding salts of sulfonated and /or non-sulfonated fatty acids can also be used as co-emulsifiers. 10. Use according to one of claims 1 to 9 of the ester sulfonate salts in amounts of 0.1 to 10 wt-#, preferably 0.5 to 5 wt-# and especially in amounts of 1 to 3 wt-#, all calculated on the sum of water plus oil . 11. Use according to claims 1 to 10 where the emulsifiers on an ester sulfonate salt basis are used together with ecologically acceptable oil phases, whereby here ester oils from monocarboxylic acids and/or polycarboxylic acids with mono- and/or polyfunctional alcohols, corresponding ester oils of carbonic acid, oleophilic alcohols and/or corresponding ethers, are preferred oil phases and thereby particularly chosen in such a way that in practical use, or during partial ester saponification, some toxicological and especially inhalation toxicological risks are triggered. 12. Use according to claims 1 to 11 of the ester sulphonate salts together with oil phases or oil mixture phases whose flash point is at least at 100°C and preferably above 135°C. 13. Use according to claims 1 to 12 of the ester sulfonate salt-based emulsifiers in pourable and pumpable invert systems with continuous oil phases whose solidification values (pour and solidification points for the oil phase) are below 0°C and preferably below -5°C and thereby, in the temperature range 0 to 5°C, exhibits a Brookfield (RVT) viscosity of not more than 55 mPas, preferably not more than 45 mPas, while the dispersed oil phase when using the emulsifiers in oil-in-water emulsions at 20°C, can exhibit a Brookfield (RVT )viscosity of approx. 3,000,000 mPas, preferably approx. 1,000,000 mPas. 14. Use according to claims 1 to 13 where ecologically acceptable ester sulfonate salt emulsifiers are used together with an oil phase which at least partially contains ester oils of monocarboxylic acids from at least one of the following subclasses: a) Esters of C^_g-monocarboxylic acids and mono- and/or polyfunctional alcohols whereby the residues of monohydric alcohols exhibit at least 6 and preferably at least 8 C atoms and the polyhydric alcohols preferably have 2 to 6 C atoms in the molecule, b) Esters of monocarboxylic acids of synthetic and/or natural origin with 6 to 16 C atoms, in particular esters of corresponding aliphatic, saturated monocarboxylic acids and mono- and/or polyfunctional alcohols of the type mentioned under a) c) esters of olefinic mono- and/or polyunsaturated dicarboxylic acids with at least 16 and especially 16 to 24 C atoms and especially monofunctional straight and/or branched alcohols. 15 . Invert drilling mud which is suitable for the environmentally friendly exploitation of geological deposits and which in a continuous oil phase contains a dispersed aqueous phase together with emulsifiers and common additional auxiliaries, for example thickeners, fluid loss additives, weighting agents, water-soluble salts and alkali reserves, characterized in that they together with an ecologically acceptable continuous oil phase contains surface-active ester sulphonate salts of the type specified in claim 1 as an emulsifier or as an emulsifier component. 16. Invert drilling mud according to claim 15, characterized in that it contains ester oils, oleophilic alcohols and/or corresponding ethers as an ecologically acceptable continuous oil phase. 17. Invert drilling mud according to claims 15 and 16, characterized in that it exhibits a plastic viscosity (PV) in the range 10 to 60 mPas and a yield point (Yield Point, YP) in the range 5 to 40 lb/100 ft<2> (1 lb/ 100 ft<2>= 2.0885 Pa), all determined at 50°C. 18. Invert drilling mud according to claims 15 to 17, characterized in that, with the co-use of ester oils in the continuous oil phase, in particular corresponding esters of monocarboxylic acids, of polycarboxylic acids and/or carbonic acid, these ester oils make up at least one third and preferably the predominant part of the ecologically acceptable oil phase . 19. Invert drilling mud according to claims 15 to 18, characterized in that its dispersed water content amounts to 5 to 50 wt-# and preferably 10 to 30 wt-# and in particular contains salts of the type CaCl2 and/or KC1 in dissolved form. 20. Invert drilling mud according to claims 15 to 20, characterized in that the oil phase in the invert mud in the temperature range 0 to 5°C exhibits a Brookfield (RVT) viscosity below 50 mPas, preferably not above 40 mPas.