JPH0115550B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a plugging fluid for drilling wells containing a novel organophilic clay gelling agent. More specifically, it relates to a closing fluid for drilling wells that is used to insulate the casing inside the oil well bore from geothermal heat by introducing a pump into the annular space inside the oil well bore and then allowing it to stand to change into a non-flowing gel. It is something. [Prior Art and its Problems] Conventionally, in drilling an oil well, it has been known to use both well drilling fluid and plugging fluid. Closing fluid enhances insulation from geothermal heat by providing higher gel strength and insulation properties than drilling fluid. It is known in the art to include organophilic clays in the drilling and plugging fluids for drilling oil wells. Conventionally, organophilic clay compounds are reacted by ion exchange under suitable conditions with clays containing exchangeable cations and negative layered lattices to form organophilic clay products. If the organic cation contains at least one alkyl group of at least 10 carbon atoms, the resulting organophilic clay has the property of swelling in certain organic liquids. Organophilic clay was trademarked in the early 1950s
Since its introduction to the market as BENTONE, by adding low molecular weight polar organic substances to the composition,
It has become well known that maximum gelling (thickening) effect is obtained from these organophilic clays. Such polar organic substances are variously called dispersants, dispersion aids, solvating agents, dispersion aids, and the like. The most effective and accepted polar substances for use as dispersants have been found to be low molecular weight alcohols and ketones, particularly methenol and acetone. However, these dispersants have very low flash points, requiring the use of flame protection equipment. Higher boiling point and higher flash point dispersants can also be used, but these are less effective and often result in gels with poor secondary properties, such as mechanical or storage stability. However, organophilic clay has a temperature of 12.8℃ (55
〓) When incorporated into an organic system at temperatures lower than It takes several hours. Therefore, it is desirable to have an organophilic clay that is easily dispersed in the oil phase of an oil-based emulsion fluid as a closure fluid for well drilling, while at the same time achieving almost complete gelation in a short period of time even under low shear. ing. [Object of the Invention] Therefore, it is an object of the present invention to obtain a geothermal oil-based emulsion fluid that can be easily prepared at the drilling site using simple stirring equipment, is pumpable, and produces a gel with excellent temperature characteristics. The purpose of the present invention is to provide a closing fluid for drilling wells suitable for insulation. [Summary of the Invention] In order to achieve the above object, the plugging liquid for drilling wells according to the present invention comprises an oil phase, a dispersed aqueous phase, and an organophilic clay gelling agent, the organophilic clay gelling agent 20-35% methylbenzylalkylammonium compounds with alkyl groups having 16 carbon atoms and 60-75% methylbenzylalkylammonium compounds having alkyl groups having 18 carbon atoms
and a mixture of methylbenzyl dialkyl ammonium compounds containing at least
consisting of a reaction product with a smectite-type clay having a cation exchange capacity of 75 milliequivalents, and further the amount of said ammonium compound is from 100 to 120 milliequivalents per 100 g of clay, based on 100% active clay;
28.6 to 85.6 g of the organophilic clay gelling agent/
(from about 6 to about 30 pounds per barrel) is a thixotropic fluid that exhibits higher gel strength and thermal insulation properties than well fluids. The plugging fluid according to the invention exhibits higher gel strength and improved thermal insulation properties than well drilling fluids due to the use of a higher amount (28.6 to 85.6 g/) of said organophilic clay gelling agent than in drilling fluids. . The clay used to prepare the organophilic clay thickener of the present invention is a smectite type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay. Particularly desirable types of clays are clays such as naturally occurring Wyoming species swellable bentonite, and hectorite or swellable magnesium-lithium silicate clays. Clays, particularly bentonite type clays, are preferably converted to the sodium form if they are not already in this form. This can be conveniently accomplished by preparing an aqueous slurry of clay and passing this slurry through a bed of cation exchange resin in the sodium form. Alternatively, the clay can be mixed with water and a soluble sodium compound (eg, sodium carbonate, sodium hydroxide, etc.) and the mixture sheared in a mill or extruder. Smectite-type clays synthesized by either pneumatic or preferably hydrothermal synthesis methods can also be used to prepare the organophilic clays of the present invention. Representative such clays are montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite. These clays contain mixed hydroxides of the desired metals, optionally with or without sodium fluoride or alternatively exchangeable cations or mixtures thereof, in proportions of smectites of the specific synthesis desired. It can be synthesized hydrothermally by forming an aqueous reaction mixture in the form of a slurry. The slurry is then placed in an autoclave and heated under autogenous pressure to a temperature in the range of about 100-325°C, preferably 274-300°C, for a sufficient time to produce the desired product. Organic compounds that can be used in the practice of the present invention include:
1 methyl group, 1 benzyl group, and 14 or more carbon atoms
A quaternary ammonium salt containing a mixture of 20 alkyl groups, where 20-35% of the alkyl groups are of 16 carbon atoms and 60% of the alkyl groups are of 18 carbon atoms. ~75%. The anion of the salt is preferably selected from chloride or bromide or a mixture thereof, particularly preferably chloride, but for example acetate,
Other anions such as hydroxide ion, nitrate ion etc. may be present in the quaternary ammonium salt to
It is also possible to neutralize class ammonium cations. Methylbenzyl dialkyl ammonium salt has the formula [In the formula, R ₁ is CH ₃ , R ₂ is C ₆ H ₅ CH ₂ , R ₃ and
R ₄ is an alkyl group having 14 to 20 carbon atoms, and 20 to 35% of these alkyl groups have carbon atoms
16 and 60-75% have 18 carbon atoms,
In the formula, M ^- is preferably CI ^- , Br ^- , NO ₂ ^- ,
selected from the group consisting of OH ^- , CH ₃ COO ^- and mixtures thereof]. A preferred quaternary amine for use in the practice of this invention is methylbenzyl dihydrogenated tallow ammonium chloride. Here, methylbenzyl dihydrogenated tallow ammonium chloride refers to the alkyl group of methylbenzyl dialkylammonium chloride derived from the fatty acid that constitutes the so-called hydrogenated oil obtained by hydrogenating tallow such as beef tallow and pork tallow. (alkyl group having the same number of carbon atoms including the carbon of the carboxyl group). The analytical values for industrially produced hydrogenated tallow are typically 2.0% _C14 , 0.5% _C15 , 29.0% _C16 ,
It is an alkyl group with 1.5% _C17 , 66.0% _C18 , and 1.0% _C20 . Alkyl groups can be obtained from natural oils, including, for example, various vegetable oils such as corn oil, soybean oil, cottonseed oil, castor oil, etc., and various animal fats and oils. This alkyl group may be derived from petroleum, such as alpha olefin. Many methods are known for producing methylbenzyl dialkyl ammonium salts. Generally, those skilled in the art will understand that, for example, a fatty acid is treated with ammonia to form an acid amide compound, and this acid amide compound is dehydrated to form a nitrile compound.
By hydrogenation of this nitrile, dialkyl secondary
A methyldialkyl tertiary amine is prepared by ring alkylation using formaldehyde as the methyl group source, and then a quaternary amine is prepared by addition of benzyl chloride or bromide to the tertiary amine. will produce a grade amine halide. The organophilic clay of the present invention is preferably prepared for a period of time sufficient to coat the clay particles with the organic compound.
38℃ (100〓) to 82℃ (180〓), particularly preferably
Manufactured by mixing clay, quaternary ammonium compound and water at a temperature ranging from 60°C (140〓) to 77°C (170〓), followed by filtering, washing, drying and grinding. Can be done. If organophilic clay is used in the emulsion, the drying and milling steps can be omitted. If the clay, quaternary ammonium compound, and water are mixed at concentrations such that no slurry is formed, the passing and washing steps can be omitted. Preferably, the clay is dispersed in water at a concentration of about 3% to 7%, optionally centrifuging the slurry to remove non-clay impurities comprising about 10% to about 50% of the starting clay composition; Stir the slurry and 60℃
(140〓) to 77℃ (170〓),
The quaternary amine is added in the desired milliequivalent ratio, preferably as a liquid in isopropanol or as a liquid dispersed in water, and stirring is continued to carry out the reaction. The amount of methylbenzyl dialkyl ammonium salt added to the clay for purposes of this invention must be sufficient to impart the desired enhanced dispersion properties to the organophilic clay. Milliequivalent ratio is defined as the number of milliequivalents of organic compound present in the organoclay per 100 grams of clay on a 100% active clay basis. The organophilic clay of the present invention must have a milliequivalent ratio of 100 to 120, preferably 85 to 95. At lower milliequivalent ratios, the organophilic clay produced provides a less thixotropic composition, making it an ineffective gelling agent for plugging fluids used in oil well drilling. Also, at higher milliequivalent ratios, the organophilic clay becomes a poorer gelling agent. In the practice of the present invention, there is present in the well drilling plugging fluid an oil phase, a dispersed aqueous phase, and about 6 to about 30 pounds per barrel (17.1 to 18.6 g/barrel) of an organophilic clay gelling agent. Must be. The oil phase that can be used in producing the plugging fluid for well drilling according to the present invention is preferably crude oil and its fractions such as diesel oil, kerosene, fuel oil, light lubricating oil fractions,
It can be heavy naphtha with a boiling point range of about 149°C (300°) to 315°C (600°). A preferred material is diesel oil obtained from crude distillation. The aqueous phase in the present invention is water, including, for example, aqueous solutions of inorganic salts such as sodium chloride, calcium chloride, and the like. The addition of these salts can be optional, but their presence aids in excavation through organization of the hydratable clay content by increasing the percolation pressure of the aqueous phase. A complete discussion of the effects of these salts can be found in US Pat. No. 3,561,548. The exact amount of water to be incorporated into the closure fluid depends on a number of factors, including closure fluid weight requirements, desired flow characteristics, bottom hole temperatures expected to be encountered, or operational requirements placed on the closure fluid during completion operations. Determined by these factors. It has generally been found suitable to use amounts of water from 2 to 50% by volume. These amounts of water make the oil-based plugging fluid fire-resistant. Because,
This is because if oil is exposed to a temperature that could cause it to catch fire, the extinguishing effect of water vapor will occur. Furthermore, the occluding fluid has excellent resistance to water contamination, and the flow properties of the occluding fluid can be adjusted to values comparable to water-based fluids. In the compositions of the invention, water can be emulsified in the oil phase using conventional emulsifiers. The amount of emulsifier used depends primarily on the amount of water present and the degree of emulsification desired. Generally 2 to 30 lbs/barrel (5.7 to 85.6 g/), preferably 5 to 20 lbs/barrel (14.3 to 57.0 g/) have been found to be sufficient to obtain the necessary gel strength and overcontrol. . Emulsifiers include e.g.
EZ MUL emulsifier and INVERMUL oil mud concentrate (both N.
Emulsifiers can be selected from commonly used emulsifiers, such as E.L. Industries, Inc., a trademark of Balloid Division). The composition is, for example, BAROID
Optionally include conventional bulking agents such as barite to increase fluid density from 7.5 to 22 lb/gal (900 to 2640
g/), and can also contain a fluid loss adjusting agent (liquid reducing agent). The amount of organophilic clay used is an amount effective to obtain the necessary degree of gelation of the oil-based fluid as a closure fluid for well drilling. The minimum concentration of organophilic clay required to gel any particular composition depends on a number of factors, such as the type of organophilic clay used, the properties of the oil phase, and the maximum temperature to which the composition is subjected. Depends on that factor. The maximum concentration of organophilic clay that can be used is limited so that the composition provides sufficient fluidity for pumping. Amounts of organophilic clay of about 6 to about 30 pounds per barrel (17.1 to 85.6 g/barrel) have been found to be suitable for producing oil-based well drilling fluids. On the other hand, oil-based emulsions containing about 1 to 10 pounds per barrel of organophilic clay are suitable as well fluids. It has been found that when organophilic clays are incorporated into oil-based emulsion fluids, nearly complete gelation is achieved with low shear mixing. The resulting oil-based emulsion fluid has a surface temperature below -29°C (-20〓) and a temperature of 260°C.
It is a stable plugging liquid at downhole temperatures up to (500〓). Formation of a stable plugging liquid occurs within minutes after addition of the organophilic clay into the oil-based fluid and low shear mixing. According to the invention, the plugging liquid is prepared by adding water and organophilic clay, optionally containing any amount of inorganic salts, to an oil medium. The composition of the occlusive fluid is adjusted to provide a pumpable composition as described above. Emulsifiers, bulking agents and fluid weight loss regulators can be added at any time as needed. It is only necessary to obtain a stable emulsion in the oil phase of the fluid before using the fluid. Once produced, the plugging fluid is transferred, eg, by pumping, into the oil well bore and allowed to settle filling the annular space between the borehole and the wellbore tubing to form a non-flowing gel that insulates at least a portion of the geothermal heat. [Examples of the Invention] The present invention will be explained by the following examples, but the present invention is not limited thereto. All partages are by weight unless otherwise specified. Plastic viscosity, yield point and ten second gels
API RP13B, American Petroleum Institute for Fluid Testing,
Measurements were made according to the procedure described in the Standard Methods 6th Edition (April 1976). The smectite-type clays used were hectorite and Wyoming bentonite. The hectorite clay was slurried in water and centrifuged to remove substantially all non-clay impurities. The Wyoming bentonite clay was slurried in water, centrifuged to remove substantially all non-clay impurities, and the slurry was ion-exchanged to the sodium form by passing it through a bed of ion exchange resin in the sodium form. . Several samples of methylbenzyl dihydrogenated tallow ammonium chloride supplied by Enenko were used to prepare the organophilic clays in the examples. The molecular weight of these samples is
619 to 644, and the % activity in isopropanol ranged from 60% to 81.5%. Conventional refined oil and solvent refined oil had the following properties.

〔Effect of the invention〕

According to the closure fluid for drilling wells according to the present invention, it can be easily prepared at the drilling site using the same raw materials and the same equipment as the drilling fluid for drilling wells, it can be pumped underground with a well pump, and it is suitable for geothermal insulation and will not be contaminated by groundwater. An occlusive fluid is provided.

【table】

[Table] 〓 ℃ Feet square meter Feet square meter Feet square meter Feet square meter

Claims (1)

[Scope of Claims] 1. Consisting of an oil phase, a dispersed water phase, and an organophilic clay gelling agent, the organophilic clay gelling agent has 16 carbon atoms.
A mixture of methylbenzyl dialkyl ammonium compounds containing 20-35% of methylbenzylalkylammonium compounds having alkyl groups having 18 carbon atoms and 60-75% of methylbenzylalkylammonium compounds having alkyl groups having 18 carbon atoms, and 100 g of clay. the reaction product with a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per clay;
The amount of the organophilic clay gelling agent is 100 to 120 milliequivalents per 100 g, and the amount of the organophilic clay gelling agent is 28.6 to 85.6 g/(about 6 to about 30
A thixotropic plugging liquid exhibiting higher gel strength and insulating properties than well drilling fluids, characterized in that it contains a thixotropic plugging liquid in an amount of (pounds per barrel). 2. The occluding liquid according to claim 1, wherein the smectite clay is hectorite or sodium bentonite. 3. The methylbenzyl dialkyl ammonium compound is methylbenzyl dihydrogenated tallow ammonium chloride, claim 1 or 2.
Occlusive fluid as described in section. 4 The organophilic clay gelling agent has the formula [In the formula, R ₁ is CH ₃ , R ₂ is C ₆ H ₅ CH ₂ , R ₃ and
R ₄ is an alkyl group containing a mixture of 14 to 20 carbon atoms, of which 20 to 35% have 16 carbon atoms and 60 to 75% have 18 carbon atoms; M ^- is CI ^- , Br ^- , NO ₂ ^- , OH ^- and
is the reaction product of an ammonium compound having a smectite-type clay selected from the group consisting of hectorite and sodium _bentonite and a smectite-type clay selected from the group consisting of hectorite ^and sodium bentonite, the amount of said ammonium compound being 100% active The occlusion liquid according to any one of claims 1 to 3, which has an amount of 100 to 120 milliequivalents per 100 g of clay, based on clay. 5 The amount of ammonium compound is 85 per 100g of clay.
5. The occlusive fluid according to any one of claims 1 to 4, which has an amount of 95 milliequivalents. 6. The occluding liquid according to any one of claims 1 to 5, wherein the aqueous phase contains about 2 to 50% by volume of water.