JP2896199B2 - Fluid for drilling - Google Patents

Description

The present invention relates to novel drilling fluids based on ester oils, in particular esters having high ecological compatibility, good stability and performance characteristics Oil based invert drilling fluids. One important application of the novel drilling fluid is in offshore drilling for the development of crude and / or gas sources. A particular object of the present invention in this regard is to provide a technically useful drilling fluid with high ecological compatibility. The use of new drilling fluids is particularly important, but not limited to, in offshore areas. The novel drilling fluid may also be used in land drilling, including geothermal drilling, water drilling, geochemical drilling and mineral drilling. In this case, the ester-based drilling fluid selected according to the invention essentially eliminates the ecotoxicological problem to a considerable extent.

BACKGROUND OF THE INVENTION Liquid drilling fluids for drilling and cutting rocks are slightly enriched water-based or oil-based fluid systems. Oil-based systems are increasingly being used in practice, especially in offshore drilling or in penetrating water-sensitive layers.

Oil-based drilling fluids generally have a three-phase system, ie,
Fine dispersion of oils, water and additives (including emulsifiers, emulsifier systems, extenders, flow loss additives, alkali reserves, viscosity modifiers etc. to stabilize the system as a whole and to determine favorable performance characteristics) It is a form of so-called inverted emulsion mud made of materials. For details, see, for example, Journal of Petroleum Technology, 1985.
, 137-142, PABoyd et al., "New Base Oil Used in Low Toxicity Oil Mads."
-Toxicity Oil Muds) "
Of Petroleum Technology, 1984, 975-981
"New Drilling Fluid Technology-Mineral Oi" by Bennett (RBBennet) on the page
l Mud) "and the references cited therein.

Oil based drilling fluids were initially made of a diesel oil fraction containing aromatic components. Then, for detoxification and to eliminate ecological problems, as a continuous oil phase, a hydrocarbon fraction substantially free of aromatic compounds,
It has been proposed to use what is presently known as "non-polluting oil" (see supra). Although some advantages have been achieved by not using aromatic compounds in this way, there is an urgent need to further reduce the environmental problems created by such drilling fluids. This is especially true in drilling offshore wells for the development of oil and gas sources. Marine ecosystems are particularly sensitive to the introduction of toxic and non-degradable substances.

Related art has recognized the importance of ester-based oil phases to solve these problems. United States Patent 4,
Nos. 374,737 and 4,481,121 describe oil-based drilling fluids that use non-polluting oils. Non-aromatic mineral oil fractions and vegetable oils such as peanut oil, soybean oil, linseed oil, corn oil, rice oil, and even animal oils such as whale oil are described as non-polluting oils. All of the plant and animal derived ester oils listed here are known to be environmentally safe and, even if dearomatized, are significantly ecologically superior to the hydrocarbon fraction. It is a natural fatty acid triglyceride.

However, the example in the aforementioned US patent is:
It does not describe the use of such natural ester oils in invert drilling mud. Throughout, the mineral oil fraction is used as the continuous oil phase.

According to the research underlying the present invention, the use of readily degradable oils of plant and / or animal origin, discussed in the prior art, is not possible for practical reasons. The rheological properties of such an oil phase are, on the one hand, 0-5 ° C., on the other hand
Uncontrollable over a wide temperature range up to 250 ° C and above.

U.S. Pat.No. 4,481,121 does not only mention triglycerides in the general description,
Mention is also made of the commercial product "Arizona 208" from Di Arizona Chemical Company, Wayne, NJ, which is a purified isooctyl-monoalcohol ester of high purity tall oil fatty acids. The esters of monofunctional alcohols and monofunctional carboxylic acids mentioned here for the first time are described as equivalents of natural triglycerides and / or dearomatized hydrocarbon fractions.

The U.S. patent does not include a workable example for the use of such an ester of a monofunctional component.

The present invention is based on ester oils, which corresponds in storage and in use behavior to the best of the oil-based drilling fluids known hitherto, but with the added advantage of increased environmental compatibility. It is based on the discovery that it is indeed possible to produce oil-based invert drilling fluids. In this regard, two important findings predominate in the present invention.

In a first important discovery, triglycerides present in the form of natural oils are not suitable for the production of mineral-free oil-based invert drilling fluids, but are not compatible with monofunctional carboxylic acids derived from these oils and fats. Esters of functional alcohols are suitable for producing such drilling fluids. A second important finding is that ester oils of this kind do not actually exhibit the same in-use behavior as previously used mineral oil fractions based purely on hydrocarbons. In practical applications, the ester oil of the monofunctional component undergoes partial hydrolysis to form free fatty acids. These free fatty acids react with the alkaline components always present in the drilling fluid, for example with the alkaline reserve used to prevent corrosion, to form the corresponding salts. About common in natural fats and oils
Salts of acids in the C ₁₆ -C ₂₄ range with highly hydrophilic bases are known to be compounds with fairly high HLB numbers, leading to the formation and stabilization of oil / water emulsions. It is used to a considerable extent in the field of cleaning and cleaning agents. However, the formation of undesirably large amounts of such oil / water emulsifier systems hinders the water / oil emulsions required to solve the problem addressed by the present invention and is therefore problematic. The teachings of the present invention, as described below, show that invert drilling fluids based on ester oil can be used effectively in spite of these difficulties inherent in the system.

DISCLOSURE OF THE INVENTION Accordingly, in a first aspect, the present invention provides a monofunctional C ₂
-C ₁₂ alcohol and olefinic mono - with and / or a mixture of polyunsaturated C ₁₆ -C ₂₄ monocarboxylic acids and or said monocarboxylic acids and minor amounts of other monocarboxylic acids, 0
An oil phase in an invert drilling mud comprising an ester that is flowable and pumpable at a temperature of ５5 ° C., said mud being suitable for environmentally safe offshore development of crude oil and gas sources. Suitable, containing a dispersed aqueous phase in a continuous oil phase together with emulsifiers, extenders, flow-loss additives, optionally other standard additives and alkali reserves, and hydrophilic, such as alkali hydroxide and / or diethanolamine. An oil phase wherein substantially no strong base is used and the addition of lime as an alkaline reserve is limited to a maximum of about 2 pounds / barrel (oil mud). About. Lime (calcium hydroxide)
It can be added as an alkaline reserve to provide protection against the ingress of CO ₂ and / or H ₂ S into the drilling fluid and thus provide protection against corrosion. Such addition of lime can be used as an alkaline reserve according to the invention. However, it is important to ensure that the amount of alkali component added is significantly reduced. In a preferred embodiment of the invention, the maximum amount of lime is on the order of 2 pounds / barrel (lime / oil mud), significantly less than the amount typically used in oil-based invert drilling fluids.

In another aspect, the present invention is suitable for offshore development of crude oil and gas sources, wherein in a continuous oil phase based on ester oil, the dispersed aqueous phase is an emulsifier, extender, flow loss additive, A mineral oil-free invert drilling fluid containing other standard additives, wherein the oil phase comprises a monofunctional alcohol having 2 to 12 carbon atoms and an olefinic mono-hydric having 16 to 24 carbon atoms.
And / or comprising an ester with a polyunsaturated monocarboxylic acid, where the water / oil emulsion is alkalized and the lime is added as an alkaline reserve, the amount of lime added is about 2 pounds / Barrel (lime /
Oil and mud). Novel drilling fluids, the oil phase is monofunctional C ₂ -C ₁₂ alcohol and olefinic mono - be made at least substantially from esters and / or C ₁₆ -C ₂₄ monocarboxylic acids polyunsaturated And the water / oil emulsion is gently alkalized, and when lime is added, the alkali reserve is preferably not more than about 2 pounds / barrel (lime / oil mud). Preferably, the lime content is slightly less than this limit.

The ester oils which form the entire continuous oil phase of the invert drilling mud or at least a substantial part thereof and which are selected according to the invention are described first below.

As mentioned above, an important criterion is the choice of the ester which is the reaction product of a monofunctional carboxylic acid and a monofunctional alcohol. Further, exclusively or at least primarily,
It is to use a C ₁₆ -C ₂₄ carboxylic acids of this kind. The carboxylic acids may be derived from unbranched or branched hydrocarbon chains, of particular interest being linear chains.
Monocarboxylic acids of this kind and their esters in the C ₁₆ -C ₂₄ range are unsuitable, mainly when they are saturated hydrocarbon compounds, because of their rather high solidification temperatures. However, esters of this type are flowable and pumpable at temperatures of 0-5 ° C, provided that an appropriate amount of the olefinically unsaturated ester component is added. Thus, in a preferred embodiment of the present invention, at least 70% by weight, preferably at least 80% by weight of said ester are olefinically unsaturated C ₁₆
~C use the esters derived from _{24-carboxylic} acid.
An important natural substance is a carboxylic acid mixture containing at least 90% by weight of an olefinically unsaturated carboxylic acid having the aforementioned carbon number range. The unsaturated carboxylic acids may be mono- and / or polyolefinically unsaturated. When using natural carboxylic acids or carboxylic acid mixtures, in addition to one ethylenic double bond in the molecule, two ethylenic double bonds and three ethylenic double bonds per carboxylic acid molecule It is preferred to have even. Details of this will be shown below.

With respect to the choice of the ester of the monofunctional reactant in the present invention, the choice of such a highly highly unsaturated carboxylic acid component in the ester oil makes the ester oil and ultimately the final invert emulsion practically practical, especially at relatively low temperatures. It ensures that it exhibits the required rheological properties. The highly unsaturated ester oils containing 16 to 24 carbon atoms in the monocarboxylic acid component used in the present invention are, in a preferred embodiment, at -10 ° C.
In the following, it has a solidification temperature (flow temperature and curing temperature) of not more than -15C. Despite the high flowability at low temperatures, the molecular size of the ester oils described in the present invention generally makes it possible for the flash point of the ester oils to be sufficiently high, above a temperature of about 100 ° C., at least 80 ° C. Be certain. 1
Ester oils having a flash point of 60 ° C. or higher are preferred. Ester oils of this type, which exhibit high flowability even at low temperatures and have a flash point of 185 ° C. or higher, can be produced without difficulty.

With these high flash points, which are determined by the size of the molecules, it is simultaneously possible to ensure that the viscosity values are within the required limits. Preferred ester oils of this type exhibit a Brookfield (RVT) viscosity at a temperature between 0 and 5 ° C. of less than or equal to 55 mPa.s, preferably less than or equal to 45 mPa.s. 30 mPa.s or less at said temperature, e.g. 20-25 mP
It is possible to adjust to the range of as.

There are two particularly important classes of unsaturated ester oils suitable for use in the present invention.

These types of first ones are those which about 35% by weight or less in di-olefinically, and that the unsaturated C ₁₆ -C ₂₄ monocarboxylic acid is a polyolefin unsaturated base if necessary. Thus, in this case, the content of polyunsaturated carboxylic acid residues in the ester oil is rather limited. However, within this class, it is preferred that at least about 60% by weight of the carboxylic acid residues are monoolefinically unsaturated.

In contrast to the first class, the second class of ester oils of practical importance is at least 45% by weight, preferably at least 45% by weight.
Above 55 weight percent are derived from C ₁₆ -C ₂₄ monocarboxylic acid mixture is derived from an acid di-olefinically and / or polyolefin unsaturated having the number of carbon atoms.

The most important monoethylenically unsaturated carboxylic acids are hexadecenoic acid (palmitoleic acid) (C ₁₆ ), oleic acid (C ₁₈ ), related ricinoleic acid (C ₁₈ ) and erucic acid (C
₂₂ ). The most important diethylenically unsaturated carboxylic acid is linoleic acid ( _C18 ), and the most important triethylenically unsaturated carboxylic acid is linolenic acid ( _C18 ).

Each of the esters formed from unsaturated monocarboxylic acids and monoalcohols may be used as an ester oil in the present invention. One example of such an ester is an ester of oleic acid, for example, isobutyl oleate. It is preferred to use acid mixtures as far as the rheology of the system is concerned and / or for reasons of availability. This is important as far as the two previous descriptions of the preferred ester oils are concerned.

As mentioned above, the first of the two is distinguished by the fact that the content of di- and polyunsaturated acids is limited and does not exceed about 35% by weight. Natural vegetable oils which give a mixture of carboxylic acids or carboxylic esters whose hydrolysis or transesterification is required are, for example, palm oil, peanut oil, castor oil and especially rapeseed oil. Suitable rapeseed oils are of the conventional type with a high erucic acid content and of the recent type with a reduced erucic acid content and an increased oleic acid content.

The first class of ester oils corresponding to this definition is of particular importance for the simple reason that problems which may arise when oxidation stability is lacking are reduced. In fact, the drilling fluid is pumped continuously,
To separate rock cut pieces by sieving, etc.
Constant contact with atmospheric oxygen at large areas and at least slightly elevated temperatures.

However, carboxylic acid mixtures of the second type also have considerable practical importance for use according to the invention. This is due to the wide availability from natural fats from animals and / or plants. C ₁₆ high content of ~C ₁₈
Or it has a C ₁₆ -C ₂₂ carboxylic acid, at the same time at least about
Examples of oils containing 45% of at least diethylenically unsaturated carboxylic acids are cottonseed oil, soybean oil, sunflower oil and linseed oil. Tall oil acids isolated during the recovery of cellulose fall within this range. However, this last class of starting materials is generally distinguished by a somewhat higher content of resin component. A typical animal-derived material for producing the corresponding carboxylic acid mixture is fish oil, especially herring oil.

As mentioned above, the ester oils used in the present invention may be selected individual esters corresponding to the above definition. However, mixtures of the esters of the corresponding monocarboxylic acids and monoalcohols are usually present. In this regard, the present invention is, on the other hand matches the viscosity condition of the present invention, the olefinically mono - and / or C ₁₆ -C ₂₄ polyunsaturated
Includes mixtures containing at least 50-51% of a monofunctional ester of a carboxylic acid. If the mixture has the requisite properties, the different constituents of the ester component, in particular,
A carboxylic acid ester of a monofunctional alcohol and a monofunctional carboxylic acid may be present as minor components of the mixture. This is important when using natural carboxylic acid mixtures. Such natural starting materials are generally also contain some major amount of saturated carboxylic acids is often encompass linear C ₁₆ -C ₁₈ carboxylic acid. Such saturated fatty acids and their esters easily cause rheological difficulties due to their rather high melting point. Therefore, according to the present invention, saturated C ₁₆ -C ₁₈ carboxylic acid is about ester oil 20
Preferably, it is up to about 10% by weight, more preferably up to about 10% by weight.

In contrast, fewer than 16 carbon atoms, preferably 12
The presence of a saturated carboxylic acid containing 1414 carbon atoms is
Permissible. Such lower fully saturated fatty acids, which are frequently present in natural starting materials in small amounts, are frequently important mixed components in solving the problem of the present invention.
These esters are less susceptible to oxidation under actual conditions of use, and their rheological properties promote the purpose of the present invention;
That is, the pure hydrocarbon oil conventionally used alone is replaced with an ester oil or an ester oil fraction.

The alcohol groups of the esters or ester mixtures according to the invention are preferably derived from straight-chain and / or branched-chain saturated alcohols. Of importance are alcohols having at least 3 carbon atoms, preferably those having up to about 10 carbon atoms. The alcohol may be of natural origin, in which case the alcohol is generally obtained from the corresponding carboxylic acids or their esters by hydrogenation reduction. However, the invention is not limited to naturally occurring starting materials. In both monoalcohol and monocarboxylic acid residues, the naturally occurring starting materials may be partially or completely replaced by the corresponding components from synthetic origin. Typical examples of alcohols are the linear alcohols obtained by the Ziegler process and the corresponding oxo alcohols (branched alcohols). Similarly, the monocarboxylic acid component, especially present in the carboxylic acid mixture,
It may be derived from petrochemical synthesis. However, the advantages of naturally occurring starting materials lie in their low toxicity values, easy degradability and their availability. The natural destruction of the used oil mud requires that said type of ester oil be aerobic and anaerobically degradable.

However, the use of these ester oils in this type of invert oil mud has one important limitation. This limitation stems mainly from the initially described difficulty that carboxylic esters are susceptible to hydrolysis and therefore have a different behavior than the purely used hydrocarbon oils conventionally used.

This type of invert drilling mud, along with the continuous oil phase,
It contains a finely dispersed aqueous phase in an amount of about 5 to 45% by weight, preferably about 5 to 25% by weight. Of particular importance is about 10-25% by weight of the dispersed aqueous phase. This condition from a conventional drilling mud configuration is:
The invention is also applied to the ester-based invert drilling mud in the present invention. It is clear that in the actual continuous operation interference of equilibrium can occur in multiphase systems as a result of partial ester hydrolysis.

The situation is complicated by the fact that the drilling mud in the present invention always contains an alkaline reserve. This alkali reserve is used for acid gases, especially CO ₂ and / or H ₂
To provide protection against corrosion caused by the unexpected influx of ₂ S is particularly important. The risk of corrosion for drilling pipes requires a safe determination of pH values in at least a mild alkaline range, for example pH 8.5-9 and higher.

In oily muds based on pure hydrocarbon fractions as the oil phase, strongly alkaline and at the same time highly hydrophilic inorganic or organic additives are practically generally used without any difficulty. Of importance are alkali hydroxides, especially sodium hydroxide, or highly hydrophilic organic bases such as diethanolamine and / or triethanolamine, which are particularly typical additives for binding H ₂ S impurities. . In addition to and / or instead of the highly hydrophilic inorganic and organic bases, lime or even weaker basic metal oxides, especially zinc oxide or the corresponding zinc compounds, are of particular importance as the alkaline reserve. Lime is widely used as an inexpensive alkalizing agent. Significantly high contents, such as 5-10 pounds / barrel (lime / oil mud) or more, are safely used.

The use of ester type oil muds of the above type requires starting from standard practice, as far as these variables are concerned. In this case, it is necessary to keep the pH value of the drilling mud at least in the mildly alkaline range and to have a sufficient amount of alkaline reserve for the unexpected inflow of acid gases. However, at the same time, the hydrolysis of the ester
It should not be undesirably promoted by such an alkali content.

Thus, in a preferred embodiment of the present invention, large amounts of highly hydrophilic inorganic and / or organic bases are not used in the oil mud. In particular, the present invention does not use alkali hydroxides or highly hydrophilic amines such as diethanolamine and / or triethanolamine. Lime is effectively used as an alkaline reserve. In that case, the maximum amount of lime used in the drilling mud is about 2 pounds / barrel or slightly less, for example, about 1-1.
It is best to limit to 8 pounds / barrel (lime / drilling mud). In addition to or instead of lime, it is also possible to use other known alkali reserves, including basic metal oxides, such as zinc oxide and other zinc compounds. However, even when using acid binders such as these, it is important not to use excessive amounts to prevent the undesirable premature aging of the drilling mud with increased viscosity, i.e., degradation of rheological properties. It is. A particular aspect of the present invention is the formation of an undesirable amount of a highly active oil / water emulsifier to such an extent that the preferred rheological properties are retained during use for a sufficiently long period of time, even when subjected to thermal aging. Hinder or at least limit. In connection with the teachings of the prior art, which have heretofore been kept within the scope of theoretical considerations, the low toxicity of this type of ester oil can be used for the first time in practice.

Olefinically unsaturated C as defined in the present invention
₁₆ -C ₂₄ esters based on monocarboxylic acid, 0
It can flow and pump at temperatures in the range of 範 囲 5 ° C. and form at least about half of the continuous oil phase of the drilling mud. However, preferred oil phases are those in which esters or ester mixtures of the type according to the invention are very predominantly present. In one particularly important aspect of the present invention, the oil phase consists almost entirely of such ester oils. Suitable components for mixing with the ester oils defined in the present invention are the selected ester oil fractions described in particular in co-pending patent application (2). The invention also includes mixtures with such other selected ester oils.

The following rheological data applies to the preferred invert drilling mud rheology of the present invention: about 5-40 pounds / 100 (feet) ² , preferably about 10-25 pounds / 100, measured at 50 ° C. (Feet) ²
Yield point (YP), and a plastic viscosity (PV) in the range of about 10-60 mPa.s, preferably about 15-40 mPa.s. Sufficient information on the determination of these parameters, on the use measurement method and on other standard compositions of the invert oil mud is available in the prior art, for example, in the Manual, published by Balloid Drilling Fluids, Inc.
Of Drilling Fluids Technology (Manual o
f Drilling Fluids Technology ”(especially“ Mud Testing-Tools and Techniques ”
Testing-Tools and Techniques) "and" Oil
See the section entitled "Oil Mud Technology"). Upon reviewing the disclosure, the following summaries can be summarized: Emulsifiers suitable for practical use are systems capable of forming the required water / oil emulsion. Selected lipophilic fatty acid salts, for example those based on amidoamine compounds, are particularly suitable. Examples are described in the previously cited United States Patent No. 4,374,737 and the references cited therein. A particularly suitable emulsifier is the product marketed under the trade name "EZ-MUL" by Baroid Drilling Fluids Inc.

Emulsifiers of this kind are commercially available in the form of concentrates,
For example, in each case about 2.5 to the ester oil phase
It can be used in an amount of ５5% by weight, especially about 3-4% by weight.

In fact, organophilic lignite is used as a flow-loss additive, in particular to form a non-permeable coating in the form of a substantially water-impermeable film on the well walls. Suitable amounts are, for example, about 5-7% by weight or about 15-20 pounds / barrel to the ester oil phase.

In the drilling mud of the present invention, the thickener used to increase the viscosity is used in the range of about 2-4% by weight or about 8-10 pounds / barrel to the ester oil phase. A cationically modified, finely dispersed organophilic bentonite. The bulking agents commonly used in practice are barite added in the amounts used for the specific conditions expected in the well. For example, the addition of barite may increase the specific gravity of the drilling mud to a value of up to about 2.5, preferably about
It can be increased to the range of 1.3 to 1.6.

In the invert drilling mud of the present invention, a soluble salt, generally calcium chloride and / or potassium chloride, may be added to the dispersed aqueous phase. The aqueous phase is preferably saturated at room temperature with a soluble salt.

The emulsifiers and emulsifier systems may be used to improve the oil leakiness of the mineral extender. In addition to the aminoamides, alkylbenzenesulfonates and imidazoline compounds are other examples. Additional information on the corresponding prior art can be found in UK Patent No.
2,158,437, EP-A-229,912 and West German Patent No. 32 47 123.

In addition to the above advantages, the drilling fluid of the present invention also has significantly improved lubricity when using the ester oil. This means that the drill pipe path and well
This is particularly important, for example, if the depth is off the vertical at a significant depth.

In such cases, the rotating drill pipe contacts the well wall and remains therein. Ester oils of the type used as the oil phase in the present invention have significantly better lubricating effects than conventionally used mineral oils, which is an important advantage of the present invention.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples.

Example 1 An invert drilling mud was prepared using undistilled isobutyl rapeseed oil ester as the continuous oil phase. This rapeseed oil consisted of a mixture of mainly unsaturated linear carboxylic acids substantially corresponding to the following components: 60% oleic acid, 20% linoleic acid, 9-10% linolenic acid, olefin C ₂₀ -C ₂₂ about 4% monocarboxylic acids, saturated monocarboxylic acids remaining predominantly C ₁₆ -C ₁₈ range of unsaturated.

The rapeseed oil ester used had the following characteristic data: density (20 ° C.) 0.872 g / cm ³ ; pour point −
15 ° C or less; Flash point (DIN51584) 180 ° C or more; Acid value (DGF-C
-V2) 1.2; viscosity at 0 ° C. 32 mPa.s; viscosity at 5 ° C. 24 mPa.s; no aromatic compound contained.

Invert drilling mud was prepared conventionally using the following ingredients: rapeseed oil fatty acid ester 230 ml water 26 ml organophilic bentonite 6 g (GELTONE, a product of Valoid Drilling Fluids Inc.) Lime 0.2 g Water-in-oil emulsifier 6g (EZ-MUL, a product of Valoid Drilling Fluids Ink) Barite 340g CaCl ₂ x 2H ₂ O 9.2g Organophilic lignite 20g (Duraton, Valoid Drilling Fluids Inc.) Products) plastic viscosity (PV), yield point (YP) and after 10 seconds and
The gel strength after 10 minutes was determined before aging by measuring the viscosity at 50 ° C.

Then, the invert drilling mud was placed in an autoclave at a temperature of 125 ° C. in a so-called “roller oven”.
For 16 hours to determine the effect of temperature on the stability of the emulsion. The viscosity value was measured again at 50 ° C.

The following results were obtained: Comparative Example 1 Invert drilling mud was prepared as in Example 1 except that the amount of lime was increased to 4 g, ie, beyond the limit of about 2 pounds / barrel.

The viscosity value and gel strength were measured before and after aging. The following results were obtained: Example 2 An invert drilling mud having a continuous oil phase was prepared. The oil phase consisted of distilled isobutyl oleate with the following characteristic data: density (20 ° C.) 0.86 g / c
m ³ ; viscosity (20 ° C.) 8 to 10 mPa.s; pour point −25 ° C. or less; flash point (DIN 51584) 185 ° C. or more; acid value (DGF-C-V2) 1 or less;

Drilling mud was prepared with the following composition: Isobutyl oleate 230 ml Fatty acid emulsifier 6 g (INVERMUL, a product of Valoid Drilling Fluids, Inc.) Organophilic bentonite 6 g (GELTONE II, Valoid Drilling.
13 g of organophilic lignite (DURATONE, a product of Valoid Drilling Fluids Ink) Lime 1 g of water-in-oil emulsifier 3 g (a product of EZ-MUL, Valoid Drilling Fluids, Inc.) Quartzite 270 g CaCl ₂ saturated aqueous solution 58.2 g Plastic viscosity (PV), yield point (Y
P) and the gel strength after 10 seconds and 10 minutes were determined before and after aging (16 hours at 125 ° C. in a roller oven). The following results were obtained. In the formulation used here, 1.2 g of lime substantially corresponds to the limit of 2 lb / barrel.

Comparative Example 2 An invert drilling oil emulsion was prepared as in Example 2, except that the amount of lime was increased to 2 g, ie, beyond the limit of about 2 pounds / barrel. The plastic viscosity, yield point and gel strength were measured before and after aging. The following results were obtained.

Preferred embodiments of the present invention are as follows.

A.70 wt% or more, preferably 80 wt% or more, more preferably the oil phase of claim 1, wherein the use of esters than 90% by weight are derived from olefinically unsaturated C ₁₆ -C ₂₄ carboxylic acid.

B. The ester used in the mud for drilling is -10 ° C or less,
Preferably a solidification point (pour point) of -15 ° C or lower, and 100
Oil phase according to claim 1, having a flash point of at least 160C, preferably at least 160C.

C. The oily phase according to claim 1, wherein the ester used in the drilling mud has a Brookfield (RVT) viscosity at 0-5 [deg.] C of no more than 55 mPa.s, preferably no more than 45 mPa.s.

35 wt% of the unsaturated C ₁₆ -C ₂₄ monocarboxylic acids present in D. ester following di - are derived from and polyolefin-unsaturated acids, at least about 60% by weight are monoolefinically unsaturated The oil phase according to claim 1.

E. ester mixtures present C ₁₆ -C ₂₄ 45% by weight of monocarboxylic acids or during, preferably an amount of more than 55 wt% di - and / or claim 1, wherein is derived from a polyolefin unsaturated acid Oil phase.

F. ester mixtures of saturated C ₁₆ -C ₁₈ carboxylic acid is about 20% by weight present in, especially about 10 wt% or less, preferably an oil phase according to claim 1, wherein fewer carbon atoms are contained.

G. The carboxylic acids present in the ester or ester mixture are at least predominantly linear and are preferably of plant and / or animal origin, especially plants and / or
2. The oil phase according to claim 1, wherein the oil phase is derived from fish oil triglycerides.

H. The oil according to claim 1, wherein the ester used in the drilling mud contains a finely dispersed aqueous phase with the continuous ester-based oil phase in an amount of about 5 to 45% by weight, preferably about 5 to 25% by weight. phase.

I. The oily phase according to claim 1, wherein the alcohol residue of the ester is derived from a linear and / or branched saturated alcohol, preferably containing 3 to 10 carbon atoms.

J. The fluid does not contain a significant amount of a highly hydrophilic base such as alkali hydroxide, or a highly hydrophilic amine such as diethanolamine, and a limited amount of zinc oxide type metal 3. Drilling fluid according to claim 2, wherein the oxide is present if required as an alkaline reserve in addition to or instead of lime.

K. Measured at 50 ° C and measured for plastic viscosity (P
The drilling fluid of claim 2 having a yield point (YP) in the range of V) and about 5 to 40 pounds / 100 (ft) ² .

3. The drilling fluid of claim 2, wherein the ester of the unsaturated monocarboxylic acid forms at least a major portion of the continuous oil phase of the invert drilling fluid.

M. dispersing water content of about 5 to 45 wt%, preferably about 10 to 25 wt%, drilling fluid of claim 2, wherein the containing dissolved salts of CaCl ₂ and / or KCl type.

N. Brookfield (RVT) at 0-5 ° C. where the oil phase of the fluid is below 50 mPa.s, preferably below 40 mPa.s
3. The drilling fluid according to claim 2, which has a viscosity.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Klaus-Peter Herold, Germany 4020 Mettmann, No. 26, Ostprussenstraße (72) Inventor Stephen von Tapavitza Germany 4006 Airkrate 2, Thomas-Mann-Strasse No. 12 (72) Inventor Douglas John Grimes, Beaconsfield E. 9.2 Pisette, UK, Redborough Lane No. 12 (72) Inventor Jean-Marc Brown Germany 3100 Celle, Bernstor Hustrasse 34A (72) Inventor Scheart P.T.Smith United Kingdom Scotland, Kinker Jinshire, Banco -, Kleeg-Graf-Dramok (No address is indicated) (56) References JP-A-57-164185 (JP, A) JP-A-4-46985 (JP, A) JP-A-4-503221 (JP, A) A) Tokio Table 4-503966 (JP, A) Tokio Table 4-503965 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) C09K 7/00-7/08

Claims (2)

(57) [Claims] 1. A mixture of a monofunctional C ₂ -C ₁₂ alcohol with an olefinic mono- and / or polyunsaturated C ₁₆ -C ₂₄ monocarboxylic acid or a mixture of said monocarboxylic acid and small amounts of other monocarboxylic acids. Comprising an ester that is flowable and pumpable at a temperature of 0-5 ° C.
An oil phase in the invert drilling mud, said mud being suitable for environmentally safe offshore development of crude oil and gas sources, emulsifying, extending, dispersing the aqueous phase in a continuous oil phase;
Includes flow loss additives, optionally with other standard additives and alkali reserves, substantially free of strong hydrophilic bases and the addition of lime as an alkali reserve of about 2 lb / barrel (oil mud). Oil phase limited to maximum value. 2. In a continuous oil phase based on ester oils, suitable for offshore development of crude oils and gas sources, the dispersed aqueous phase comprises an emulsifier, a bulking agent, a flow-loss additive and optionally other standard additives. Mineral oil-free invert drilling fluid containing an oil phase, wherein the oil phase comprises a monofunctional alcohol having 2 to 12 carbon atoms and an olefinic mono- and / or polyolefin having 16 to 24 carbon atoms. Comprising an ester with an unsaturated monocarboxylic acid, wherein the water / oil emulsion is alkalized and lime is added as an alkali reserve,
Drilling fluids that do not add more than about 2 pounds / barrel (lime / oil mud) of lime.