JP2896200B2 - New drilling fluid - 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,
It is commonly used in the form of a so-called inverted emulsion mud consisting of oil, water and finely dispersed solids. This emulsion is a water / oil emulsion, ie, the aqueous phase is present as a fine dispersion in the continuous oil phase. To stabilize the system as a whole and to determine favorable performance characteristics,
There is a wide range of additives, including emulsifiers, emulsifier systems, extenders, flow loss additives, alkali reserves, viscosity modifiers, and the like. For details, see, for example, Journal of Petroleum Technology.
Roleum Technology), 1985, pp. 137-142, by PABoyd et al., "New Base Oil Used in Rotoxicity Oil Mads (Ne
w Base Oil Used in Low-Toxicity Oil Muds) and Bennett (RBBBenne) in the Journal of Petroleum Technology, 1984, pp. 975-981.
t) “New Drilling Fluid Technology-Mineral Oil Mud”
Technology-Mineral Oil 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 oil phases 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
C acids having a chain length of up to _24, in particular salts with highly hydrophilic bases and acids substantial long chain ranging from about C ₁₆ -C ₂₂ is significantly higher leading to the formation and stabilization of oil / water emulsion HL
It is known that the compound has a B value. It is used to a considerable extent in the field of cleaning and cleaning agents. However, undesirably large amounts of such oils /
The formation of a water emulsifier system hinders the water / oil emulsion needed 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 the first gist, the present invention provides 2 to 12,
Especially monofunctional alcohols having 4 to 12 carbon atoms
Fluid with an aliphatic saturated monocarboxylic acid having 12 to 16 carbon atoms or a mixture of said monocarboxylic acid and at most equal amounts of other monocarboxylic acids at a temperature of 0 to 5 ° C. and An oil phase in an invert drilling mud comprising an ester that is pumpable, wherein the mud is suitable for environmentally safe offshore development of crude oil and gas sources, and comprises water dispersed in a continuous oil phase. An oil phase containing a phase with emulsifiers, extenders, flow loss additives and, optionally, other standard additives. About.

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 an ester oil, the dispersed aqueous phase is emulsifier, viscosity modifier, extender, flow loss additive. And, optionally, 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 12 to 16 carbon atoms. An ester with an aliphatic saturated monocarboxylic acid having an atom, wherein the ester in the oil phase is 0%.
Drilling fluid having a Brookfield (RVT) viscosity of 50 mPa.s or less at ~ 5 ° C. According to a preferred embodiment of the present invention, the ester oil in the continuous oil phase has
It has a Brookfield (RVT) viscosity of less than mPa.s.

In a particularly preferred embodiment, at least a major part of the used ester oils, ie at least about 50-51% aliphatic C ₁₂
-C ₁₄ consists monocarboxylic acids, there carboxylic acid mixture of at least about 60% by weight of such fatty respect thereof C ₁₂
-C ₁₄ ester oil is an ester consisting of monocarboxylic acids are particularly suitable.

In one important embodiment, the ester oil is the C ₁₂
-C ₁₆ range, especially containing only saturated aliphatic monocarboxylic acids C ₁₂ -C ₁₄ range. However, the present invention is not limited to this range. It may be advantageous to use esters of other carboxylic acids in at most substantially the same amount, preferably in small amounts. In this case, very short-chain aliphatic monocarboxylic acids or esters thereof and / or esters of very long-chain carboxylic acids are conceivable. However, when using very long-chain carboxylic acid esters, preference is given to using, at least in part, the corresponding mono- and / or polyolefinically unsaturated, very long-chain carboxylic acid derivatives. In this embodiment, suitable mixing components are, inter alia, mono- and / or polyolefinically unsaturated C ₁₆ -C ₂₄ , especially C ₁₈ -C ₂₂ , monocarboxylic esters.

In another important and preferred embodiment of the invention described in detail below, in an invert drilling mud in which the ester oil as defined herein is present, a significant amount of a strong hydrophilic base, such as alkali hydroxide and / or Or do not use diethanolamine.

Invert drilling mud with a continuous oil phase always contains an alkaline reserve. The alkaline reserve provides protection against ingress of CO ₂ and / or H ₂ S into the drilling mud,
Protect metal parts of drilling pipes from corrosion. Alkali reserves useful in the present invention include lime (calcium hydroxide) or less basic metal oxides such as zinc oxide and / or other zinc compounds.
These details of the teachings of the present invention will be described later.
The ester oils selected in the present invention to form all or at least a major portion of the continuous oil phase of the invert drilling mud are now described.

The ester oils of monofunctional alcohols and monocarboxylic acids used in the present invention can be derived from unbranched or branched hydrocarbon chains. Esters of the corresponding linear acids are preferred.
Saturated C ₁₂ -C ₁₆ , especially C ₁₂ -C ₁₄ monocarboxylic acids, and monofunctional alcohols having a carbon chain length as defined in the present invention have the appropriate rheological properties, even at temperatures of 0-5 ° C. In particular, it is possible to form ester oils which are flowable and pumpable at that temperature. In the present invention, an ester preferable as the oil phase of the drilling mud is 50 mP at a temperature of 0 to 5 ° C.
It is a saturated component having a Brookfield (RVT) viscosity of not more than as, preferably not more than 40 mPa.s. By selecting suitable components for the ester forming reaction, the viscosity in the above temperature range is reduced to about 30 mPa.s or less, for example, about 10 to 20 mPa.s.
Can be adjusted to a value in the range of This is an important advantage in offshore drilling where the surrounding water is very cold.

In a preferred embodiment, the ester oils used in the present invention based on the selected individual components or ester mixtures have a solidification temperature (pour point and cure point) of -10 ° C or lower, especially -15 ° C or lower in a preferred embodiment. Have. Despite the high flowability at low temperatures, the molecular size of the ester oil of the invention ensures that the flash point of the ester oil is sufficiently high, generally above a temperature of about 100 ° C., at least 80 ° C. . Ester oils having a flash point of 150-160 ° C or higher are preferred. Such ester oils having a flash point of 185 ° C. or higher can be produced.

In another important embodiment, the ester oils necessary for the present invention containing a saturated C ₁₂ -C ₁₆ monocarboxylic acid is primarily derived from the plant-derived substances. The carboxylic acid mixture or carboxylic acid mainly containing a saturated monocarboxylic acid in the above range is, for example, triglyceride, for example, coconut oil,
Obtained from palm oil and / or babassu palm oil.
The fatty acid mixtures derived from the limited amount of generally at most about 15% of the lower fatty acids (C ₆ ~C ₁₀₎ normally contained. The content of C ₁₂ -C ₁₄ acid is a major carboxylic acid mixture, generally at least 50%, is usually 60% or more. A small remainder is higher fatty acids where the unsaturated components play a significant role. Thus, carboxylic acid mixtures of this kind, due to their structure, readily give substances with satisfactory rheological properties.

In one embodiment of the invention, the natural suitable admixture is, in particular, a monofunctional ester oil as described in co-pending patent application (1). However, in the present invention, it is preferable to use these mixed components in small amounts (at most about 49% based on the ester oil mixture). In order to complete the disclosure of the present invention, such possible mixed components are briefly described below. For details, reference can be made to Patent Application (1) of the same date.

Possible mixing components are monofunctional C ₂ -C ₁₂ alcohols and mono- and / or polyolefinically unsaturated C ₁₆ -C ₁₂ alcohols.
It is an ester with ₂₄ monocarboxylic acids. Again, in this case,
The carboxylic acids may be derived from unbranched or branched hydrocarbon chains, of which linear acids are particularly important. If a suitable amount of the olefinically unsaturated ester component is kept, the long chain length ester is flowable and pumpable at temperatures of 0-5 ° C. Accordingly, in a preferred embodiment of the present invention, 70 wt% or more, preferably at least 80% by weight to use olefinically C ₁₆ -C ₂₄ esters of this type are derived from carboxylic acids of the unsaturated. Important natural substances are
A carboxylic acid mixture containing at least 90% by weight of an olefinically unsaturated carboxylic acid having the above 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 even to a lesser extent three ethylenic double bonds per carboxylic acid molecule Plays a role.

These esters of unsaturated, very long-chain monocarboxylic acids used as mixing components preferably have a solidification temperature (pour point and cure point) of -10 ° C or less, more preferably -15 ° C or less. . Due to the size of these molecules, these mixed components have a preferred range of flash points, i.e.
It has a flash point of at least 80 ° C, preferably at least 100 ° C, particularly preferably at least 160 ° C. In a preferred embodiment, this type of mixed component has a temperature of 55 mPa.s at 0-5 ° C.
Or less, preferably less than 45 mPa.s Brookfield (R
VT) It has viscosity.

Of these highly unsaturated mixed components, the most important two are:
There are two types.

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 of the 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 the unsaturated monocarboxylic acids and monoalcohols may be used as a mixing component. One example of such an ester is an ester of oleic acid, for example, isobutyl oleate. It is preferred to use an acid mixture as far as the rheology of the system is concerned and / or for reasons of availability.

Natural vegetable oils whose hydrolysis or transesterification gives a mixture of the first type of carboxylic acids or carboxylic esters are, for example, palm oil, peanut oil, castor oil and especially rapeseed oil. Suitable rapeseed oil is
One of the conventional type with a high erucic acid content and the more recent type with a reduced erucic acid content and an increased oleic acid content.

Said second type of carboxylic acid mixture is also animal and / or
Alternatively, it is widely available from plant-derived natural fats. Examples of oils containing C ₁₆ -C ₁₈ or C ₁₆ -C ₂₂ carboxylic acids high content, containing simultaneously at least about 45% of at least diethylene to 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. A typical animal-derived material for producing the corresponding carboxylic acid mixture is fish oil, especially herring oil.

Other factors to consider in selecting a saturated ester oil for use in the present invention, especially the ester oil mixture, are:
That is, saturated carboxylic esters having 16 or more carbon atoms have a rather high melting point, thus easily creating rheological difficulties. According to the present invention, saturated carboxylic acids having 16 to 18 or more carbon atoms comprise up to about 20% by weight of the ester oil, especially about 10% by weight.
It is preferable that the content be not more than weight%.

In contrast, the presence of a saturated carboxylic acid having less than 12 carbon atoms is more tolerable. These can be important mixing components for the ester oil phase selected in the present invention. These esters, like the saturated main components according to the present invention (especially in the C ₁₂ -C ₁₄ range), resistant to oxidation under the actual usage conditions. The rheological properties of the lower fatty acid esters facilitate the purpose of the present invention, i.e. to at least partially, preferably principally or completely, convert pure hydrocarbon oils which have hitherto only been used in practice. Replace with ester oil or 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 4 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, 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, it should be considered that this type of ester oil is used as the sole or major component in the invert oil mud of the present invention. This is primarily related to the difficulty mentioned at the outset that carboxylic esters are susceptible to hydrolysis and behave differently than the purely hydrolytically stable hydrocarbon oils conventionally used.

The invert drilling mud of the present invention, together 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 oil muds of the above type may require 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 must 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 in place of lime, it is also possible to use other known alkali reserves, including basic metal oxides, for example zinc oxide. But,
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. . The special gist of the present invention is:
In use, it is intended to prevent or at least limit the formation of undesirable amounts of highly active oil / water emulsifiers to such an extent that the preferred rheological properties are retained for a sufficiently long time even when subjected to thermal aging. . 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.

Esters of C ₁₂ -C ₁₆ monocarboxylic acids, saturated as defined in the present invention based can flow pumped at a temperature in the range of 0 to 5 ° C., at least about half of the continuous oil phase of the drilling mud Form. However, preferred oil phases are those in which esters of the type according to the invention are very predominant. In one particularly important aspect of the present invention, the oil phase consists almost entirely of such ester oils. Ingredients suitable for mixing with the ester oils defined in the present invention are, in particular, the compounds described in patent application (1) filed on the same date. 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"). The following is a summary from the disclosure: An emulsifier suitable for practical use is a system that can form 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 and can be used, for example, in amounts of about 2.5 to 5% by weight, in particular in each case about 3 to 4% by weight, based on the ester oil phase.

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 a significantly better lubricating effect 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.

In the following Examples and Comparative Examples, distilled lauric acid / n-hexyl ester was used as an ester oil for forming a continuous oil phase. This is the flash point above 165 ° C,
Pour point below -5 ° C, density between 0.857 and 0.861 (20 ° C), 1
The following iodine and acid values, water content below 0.3 and the following viscosity data (Brookfield, mPa.s): -5
22.5-22.5 at ° C; 15-18 at + 2 ° C; 15-18 at + 5 ° C; +10
It was a pale yellow liquid with about 15 ° C .; 12-14 at 20 ° C.

Example 1 A water-in-oil type invert drilling mud was prepared from the following components by a known method. Next, the viscosity data before and after aging were measured as follows.

The viscosity is measured by NL Baroid Fann3
Performed at 50 ° C. using a 5 viscometer. The plastic viscosity (PV), the yield point (YP) and the gel strength after 10 seconds and 10 minutes (pounds / 100 (ft) ² ) were measured by known methods.

Measurements were made before and after aging. Aging was performed in an autoclave at 125 ° C. for 16 hours in a so-called roller oven.

 The following compositions were selected for the drilling mud.

Ester oil 230ml Water 26ml Organic bentonite 6g (GELTONE II, Baroid Drilling
Products of Fluids Inc.) Organic lignite 6g (DURATONE, product of Valoid Drilling Fluids Inc.) Lime 1g Water-in-oil emulsifier 6g (Product of EZ-MUL, Valoid Drilling Fluids Inc.) 346 g of crystallite 9.2 g of CaCl ₂ x 2H ₂ O In this formulation, about 1.35 g of lime corresponds to a limit of 2 lb / barrel.

The following table shows the characteristic data obtained for the materials before and after aging as described above: Comparative Example 1 Mud for invert excavation was prepared in the same manner as in Example 1 except that the amount of lime was increased three times (3 g).

The property data obtained for the materials before and after aging are shown in the following table: Example 2 A heavy weight invert drilling mud was prepared with the following formulation: Ester oil 184 ml Water 10 ml Organophilic bentonite 2 g (GELTONE II, Baroid Drilling.
Product of Fluids Ink) Organic-friendly lignite 20g (DURATONE, product of Valoid Drilling Fluids Ink) Lime 1g Water-in-oil emulsifier 10g (Product of EZ-MUL, Product of Valoid Drilling Fluids Ink) Crystallite 568 g CaCl ₂ x 2H ₂ O 4.8 g In the same manner as in Example 1, characteristic data before and after aging were measured. The results are shown in the following table: In this example, about 1.04 g of lime corresponds to a limit of 2 pounds / barrel.

Comparative Example 2 Excavation mud was prepared in the same manner as in Example 2, except that the amount of lime was doubled (2 g). The characteristic data was measured before and after aging. The results are shown in the following table: Preferred embodiments of the present invention are as follows.

A. Use of at least about 60% by weight ester oil is an ester consisting of an aliphatic C ₁₂ -C ₁₄ monocarboxylic acid to the carboxylic acid mixture, if desired, aliphatic remaining quite short and / or 2. The oily phase according to claim 1, which is a substantially long-chain monocarboxylic acid, in particular a mono- and / or polyolefinically unsaturated monocarboxylic acid.

2. The oil phase according to claim 1, wherein the ester oil is used in an alkalized drilling mud with an alkali reserve, and lime and / or zinc oxide type metal oxides are present as an alkali reserve.

C. About 2 pounds / barrel (lime /
2. The oil phase according to claim 1, wherein the ester oil is used in drilling mud containing lime in the following amount.

D. No ester used in the oil phase of drilling mud
50 mPa.s or less at ~ 5 ° C, preferably 40 mPa.s or less,
2. The oily phase of claim 1 having a Brookfield (RVT) viscosity of about 30 mPa.s or less.

E. The ester used in the drilling mud has a solidification temperature (pour point and hardening point) of -10C or less, preferably -15C or less and a flash point of 100C or more, preferably 150C or more. The oil phase according to 1.

F. The carboxylic acid present in the ester or ester mixture is at least predominantly linear, preferably of plant origin, and is derived from the corresponding triglyceride, such as coconut oil, palm oil, babassu oil Item 10. The oil phase according to Item 1.

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

H. The oily phase according to claim 1, wherein the alcohol groups of the esters used are derived from linear and / or branched saturated alcohols, preferably containing 4 to 10 carbon atoms.

I. The oily phase according to claim 1, wherein the alcohol component of the ester oil used is of vegetable and / or animal origin and is obtained by reductive hydrogenation of the corresponding carboxylic acid ester.

J. The invert drilling fluid is preferably mildly alkalized and contains an alkali reserve, but preferably does not contain a strongly hydrophilic base such as alkali hydroxide or a strongly hydrophilic amine such as diethanolamine. 2
A fluid for drilling as described.

Drilling according to claim 2, wherein the metal oxide of the K. lime and / or zinc oxide type is present as an alkaline reserve and the addition of lime is preferably up to about 2 pounds / barrel (lime / drilling fluid). For fluid.

3. The drilling fluid of claim 2 having a yield point (YP) of about 5 to 40 pounds / (ft) ² and a plastic viscosity (PV) of about 10 to 60 mPa.s, measured at L.50C.

M. The content of dispersed water is about 5 to 45% by weight, preferably about 5 to 25%
3. The drilling fluid according to claim 2, wherein the fluid is a weight percent and contains a dissolved salt of CaCl ₂ and / or KCl type. 4.

N. A drilling fluid according to claim 2 wherein the saturated monocarboxylic acid containing from 12 to 16 carbon atoms accounts for at least a major portion of the continuous oil phase of the invert drilling fluid.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Klaus-Peter Herold, Germany 4020 Mettmann, No. 26, Ostprussenstraße (72) Inventor Stephen von Tapavizza, Germany 4006 Aircrat 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 Stuart PT Smith United Kingdom Scotland, Kinker Jinshire, Bancoー, Krieg-Graf-Dramok (No address indicated) (56) References JP-A-57-164185 (JP, A) JP-A-4-45190 (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 monofunctional alcohol having from 2 to 12 carbon atoms, an aliphatic saturated monocarboxylic acid having from 12 to 16 carbon atoms, or another mono-carboxylic acid at most equal to the monocarboxylic acid. An oil phase in an invert drilling mud comprising an ester which is flowable and pumpable at a temperature of 0-5 ° C with a mixture with a carboxylic acid, said mud comprising a crude oil and a gas source. An oil phase that is suitable for environmentally safe offshore development and contains a dispersed aqueous phase in a continuous oil phase together with emulsifiers, extenders and flow loss additives. 2. A mineral oil suitable for offshore development of crude oil and gas sources, wherein the continuous oil phase based on ester oil contains a dispersed aqueous phase together with emulsifiers, viscosity modifiers, extenders and flow loss additives. An invert drilling fluid containing no oil, wherein the oil phase comprises an ester of a monofunctional alcohol having 2 to 12 carbon atoms and an aliphatic saturated monocarboxylic acid having 12 to 16 carbon atoms. The oil phase ester is 0
Drilling fluid having a Brookfield (RVT) viscosity of less than 50 mPa.s at 5 ° C.