Water-in-oil emulsion for Antarctic drilling fluid as well as preparation method and application of water-in-oil emulsion

Abstract

The invention provides a water-in-oil emulsion for Antarctic drilling fluid as well as a preparation method and application of the water-in-oil emulsion. The water-in-oil emulsion for the Antarctic drilling fluid is prepared from a drilling fluid base fluid, water, inorganic salt and an emulsifier, the drilling fluid base fluid is one of aviation kerosene or isododecane; the inorganic salt is CaCl2 and / or NaCl; the emulsifying agent is one or a combination of more than two of sodium dodecyl benzene sulfonate, Span-80 and Tween-60. The water-in-oil emulsion for the Antarctic drilling fluid has excellent emulsibility and rheological property, and can resist ultralow temperature of-35 DEG C. The problems of poor emulsion stability, difficult rock carrying, poor suspension property and the like of the drilling fluid in the polar region drilling process can be solved. In addition, compared with the South Pole pure oil-based drilling fluid, the emulsion also has the advantage of low cost.

Description

Technical Field

[0001] The present invention relates to a water-in-oil emulsion for Antarctic drilling fluid, its preparation method and application, belonging to the technical field of polar drilling. Background Art

[0002] At present, the Antarctic drilling fluids mainly include four types: oil-based drilling fluid, alcohol-based drilling fluid, ester-based drilling fluid and silicone oil drilling fluid. However, the above four drilling fluids have problems such as high cost, insufficient temperature resistance and poor rheological properties, which seriously hinder the development of Antarctic drilling technology. Therefore, it is of great significance to develop a water-in-oil emulsion for drilling fluid with relatively low cost and high performance.

[0003] In the aspect of deep oil and gas drilling, scholars have done a lot of research on the development of water-in-oil drilling fluid emulsion. Chinese patent document CN118684880A discloses a high-temperature resistant shear strength increasing agent, its preparation method and an oil-based drilling fluid, in which a white oil-based basic emulsion is prepared, and the main components include: 75% white oil + 12% CaCl 2 solution + 4% main emulsifier + 2% auxiliary emulsifier + 2% organic clay + 5% CaO. Research shows that the dynamic shear force of this emulsion is 2.04 Pa and the demulsification voltage is 425 V. Chinese patent document CN111793479A discloses an oil-based drilling fluid and its preparation method, in which an aqueous epoxy resin emulsion is prepared, and the main components include: bisphenol F type epoxy resin, sodium dodecylbenzenesulfonate, deionized water and ethylene glycol monobutyl ether. The dynamic shear force of this emulsion can reach more than 5.0 Pa and the demulsification voltage is above 1000 V. Chinese patent document CN110003865A discloses a water-in-oil emulsion, its preparation method and an oil-based drilling fluid. Among them, the water-in-oil emulsion includes an oil phase, a water phase and hydrophobically modified fumed silica. It is found that after the emulsion is placed for 6 months, its average particle size remains basically unchanged, indicating that the emulsion has good stability. However, there is no relevant report on the research of the emulsion for Antarctic ultra-low temperature drilling fluid.

[0004] Therefore, it is urgent to develop an ultra-low temperature drilling fluid emulsion suitable for the Antarctic region to improve the dispersion stability and rheological properties of the drilling fluid, and at the same time reduce the cost of the drilling fluid. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a water-in-oil emulsion for Antarctic drilling fluid, its preparation method and application. The water-in-oil emulsion for Antarctic drilling fluid of the present invention has excellent emulsifying property and rheological property, and can withstand an ultra-low temperature of -35°C. It can solve problems such as poor stability of the drilling fluid emulsion, difficult rock carrying and poor suspension in the polar drilling process. In addition, compared with the pure oil-based drilling fluid in Antarctica, this emulsion also has the advantage of low cost.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] An oil-in-water emulsion for Antarctic drilling fluid, which is prepared from a drilling fluid base fluid, water, inorganic salts and an emulsifier; the drilling fluid base fluid is one of aviation kerosene or isododecane; the inorganic salts are CaCl 2 and / or NaCl; the emulsifier is one or a combination of two or more of sodium dodecylbenzenesulfonate, Span-80, and Tween-60.

[0008] Preferably according to the present invention, the drilling fluid base fluid is aviation kerosene; the inorganic salts are CaCl 2 ; the emulsifier is sodium dodecylbenzenesulfonate.

[0009] Preferably according to the present invention, in the oil-in-water emulsion for Antarctic drilling fluid, the volume ratio of the drilling fluid base fluid to water is 80-90:10-20; the mass of the inorganic salts is 25-35% of the mass of water; the mass of the emulsifier is 1-3% of the total mass of the drilling fluid base fluid, water and inorganic salts.

[0010] According to the present invention, the preparation method of the above-mentioned oil-in-water emulsion for Antarctic drilling fluid includes the following steps:

[0011] (1) Add inorganic salts to water and stir evenly to obtain a brine solution;

[0012] (2) Add an emulsifier to the drilling fluid base fluid and stir to dissolve it to obtain a base fluid containing the emulsifier;

[0013] (3) Add the brine solution obtained in step (1) to the base fluid containing the emulsifier obtained in step (2) and stir evenly to obtain an oil-in-water emulsion for Antarctic drilling fluid.

[0014] Preferably according to the present invention, in step (1), the mass of the inorganic salts is 25-35% of the mass of deionized water.

[0015] Preferably according to the present invention, in step (2), the volume ratio of the drilling fluid base fluid to the water in step (1) is 80-90:10-20.

[0016] Preferably according to the present invention, in step (2), the mass of the emulsifier is 1-3% of the total mass of the drilling fluid base fluid, water and inorganic salts.

[0017] Preferably according to the present invention, in step (3), the rotation speed of the stirring is 5000-8000 r / min, and the stirring time is 20-30 min.

[0018] According to the present invention, the above water-in-oil emulsion for Antarctic drilling fluid is applied in polar formations and used as a drilling fluid for drilling in polar formations; preferably, the polar region is Antarctica.

[0019] The technical features and beneficial effects of the present invention are as follows:

[0020] 1. The preparation method of the present invention is simple, and the obtained water-in-oil emulsion is safe, environmentally friendly, and has no pungent odor.

[0021] 2. The water-in-oil emulsion of the present invention has a high emulsification rate under ultra-low temperature conditions, low interfacial tension, excellent long-term stability, and the emulsification rate after freezing for 16 h is above 79.8%.

[0022] 3. The water-in-oil emulsion of the present invention has excellent rheological properties under ultra-low temperature conditions. The dynamic shear force at -35°C is above 2.0 Pa, and the plastic viscosity is relatively low, which can meet the requirements of Antarctic drilling; moreover, too much or too little addition of the emulsifier in the present invention, or the change of the type of emulsifier will lead to a decrease in the adsorption amount at the emulsion interfacial film, thereby reducing the strength of the emulsion interfacial film and resulting in poor effects; at the same time, the type of inorganic salt also has an important influence. In the presence of specific CaCl 2 or NaCl in the present invention, the emulsion has a high emulsification rate, while replacing it with KCl will cause precipitation in the emulsion under ultra-low temperature conditions, affecting the emulsion performance; in addition, too high an oil-water ratio will make the strength of the network structure formed between the water droplets and the emulsifier at the oil-water interface too low, and thus the emulsion stability is poor.

[0023] 4. The water-in-oil emulsion of the present invention has excellent emulsion stability and rheological properties under ultra-low temperature conditions. Because the emulsifier is adsorbed on the oil-water interface through hydrogen bonds, electrostatic attraction, and the interaction between carbon chains, etc., the strength of the oil-water interfacial film is significantly improved, and thus the emulsion has long-term stability. In addition, the network structure formed by this action also significantly increases the dynamic shear force of the emulsion and improves its rheological properties. In summary, the obtained water-in-oil emulsion has excellent comprehensive performance, provides technical support for polar ultra-low temperature drilling engineering, and has broad application prospects. Specific Embodiments

[0024] The present invention will be further described below by specific examples, but it is not limited thereto.

[0025] The experimental methods described in the examples are all conventional methods unless otherwise specified; the reagents and materials used can be obtained from commercial channels unless otherwise specified.

[0026] The "parts" mentioned in the examples are all volume parts.

[0027] Example 1

[0028] A preparation method of a water-in-oil emulsion for Antarctic drilling fluid, comprising the following steps:

[0029] (1) Add anhydrous calcium chloride to water and stir for 6 min to prepare a brine solution; wherein, the addition amount of deionized water is 20 parts, and the mass of CaCl 2 is 30% of the mass of deionized water;

[0030] (2) Pour aviation kerosene into a slurry cup, and while stirring with a high-speed stirrer (rotation speed: 500 r / min), add sodium dodecylbenzenesulfonate and stir for 15 min to fully dissolve it, obtaining a base liquid containing an emulsifier; wherein, the addition amount of aviation kerosene is 80 parts, and the addition amount of sodium dodecylbenzenesulfonate is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0031] (3) Add the brine solution obtained in step (1) to the base liquid containing an emulsifier obtained in step (2), and stir for 25 min under the condition that the stirring rate is 6000 r / min to obtain a water-in-oil emulsion for Antarctic drilling fluid.

[0032] Example 2

[0033] A preparation method of a water-in-oil emulsion for Antarctic drilling fluid, comprising the following steps:

[0034] (1) Add anhydrous calcium chloride to water and stir for 6 min to prepare a brine solution; wherein, the addition amount of deionized water is 20 parts, and the mass of CaCl 2 is 30% of the mass of deionized water;

[0035] (2) Pour aviation kerosene into a slurry cup, and while stirring with a high-speed stirrer (rotation speed: 500 r / min), add sodium dodecylbenzenesulfonate and stir for 15 min to fully dissolve it, obtaining a base liquid containing an emulsifier; wherein, the addition amount of aviation kerosene is 80 parts, and the addition amount of sodium dodecylbenzenesulfonate is 1.5% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0036] (3) Add the brine solution obtained in step (1) to the base liquid containing an emulsifier obtained in step (2), and stir for 25 min under the condition that the stirring rate is 6000 r / min to obtain a water-in-oil emulsion for Antarctic drilling fluid.

[0037] Example 3

[0038] A preparation method of a water-in-oil emulsion for Antarctic drilling fluid, comprising the following steps:

[0039] (1) Add anhydrous calcium chloride to water and stir for 6 min to prepare a brine solution; wherein, the addition amount of deionized water is 15 parts, and the mass of CaCl 2 is 30% of the mass of deionized water;

[0040] (2) Pour the aviation kerosene into the pulp cup, and add sodium dodecylbenzenesulfonate while stirring with a high-speed stirrer (rotation speed is 500 r / min), and stir for 15 min to fully dissolve it to obtain a base liquid containing an emulsifier; among them, the addition amount of aviation kerosene is 85 parts, and the addition amount of sodium dodecylbenzenesulfonate is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0041] (3) Add the brine solution obtained in step (1) to the base liquid containing an emulsifier obtained in step (2), and stir for 25 min under the condition that the stirring rate is 6000 r / min to obtain a water-in-oil emulsion for Antarctic drilling fluid.

[0042] Example 4

[0043] A preparation method of a water-in-oil emulsion for Antarctic drilling fluid, including the following steps:

[0044] (1) Add anhydrous calcium chloride to water and stir for 6 min to prepare a brine solution; among them, the addition amount of deionized water is 20 parts, and the mass of CaCl 2 is 35% of the mass of deionized water;

[0045] (2) Pour the aviation kerosene into the pulp cup, and add sodium dodecylbenzenesulfonate while stirring with a high-speed stirrer (rotation speed is 500 r / min), and stir for 15 min to fully dissolve it to obtain a base liquid containing an emulsifier; among them, the addition amount of aviation kerosene is 80 parts, and the addition amount of sodium dodecylbenzenesulfonate is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0046] (3) Add the brine solution obtained in step (1) to the base liquid containing an emulsifier obtained in step (2), and stir for 25 min under the condition that the stirring rate is 6000 r / min to obtain a water-in-oil emulsion for Antarctic drilling fluid.

[0047] Example 5

[0048] A preparation method of a water-in-oil emulsion for Antarctic drilling fluid, including the following steps:

[0049] (1) Add anhydrous sodium chloride to water and stir for 6 min to prepare a brine solution; among them, the addition amount of deionized water is 20 parts, and the mass of NaCl is 30% of the mass of deionized water;

[0050] (2) Pour the aviation kerosene into the pulp cup, and add sodium dodecylbenzenesulfonate while stirring with a high-speed stirrer (rotation speed is 500 r / min), and stir for 15 min to fully dissolve it to obtain a base liquid containing an emulsifier; among them, the addition amount of aviation kerosene is 80 parts, and the addition amount of sodium dodecylbenzenesulfonate is 2% of the total mass of aviation kerosene, water and anhydrous sodium chloride;

[0051] (3) Add the brine solution obtained in step (1) to the base liquid containing the emulsifier obtained in step (2), and stir for 25 min under the condition that the stirring rate is 6000 r / min to obtain a water-in-oil emulsion for Antarctic drilling fluid.

[0052] Example 6

[0053] A preparation method of a water-in-oil emulsion for Antarctic drilling fluid includes the following steps:

[0054] (1) Add anhydrous calcium chloride to water and stir for 6 min to prepare a brine solution; wherein, the addition amount of deionized water is 20 parts, and the mass of CaCl 2 is 30% of the mass of deionized water;

[0055] (2) Pour isododecane (CAS No.: 31807-55-3) into a pulp cup, and add sodium dodecylbenzenesulfonate while stirring with a high-speed stirrer (rotation speed is 500 r / min), and stir for 15 min to make it fully dissolve to obtain a base liquid containing an emulsifier; wherein, the addition amount of isododecane is 80 parts, and the addition amount of sodium dodecylbenzenesulfonate is 2% of the total mass of isododecane, water and anhydrous calcium chloride;

[0056] (3) Add the brine solution obtained in step (1) to the base liquid containing the emulsifier obtained in step (2), and stir for 25 min under the condition that the stirring rate is 6000 r / min to obtain a water-in-oil emulsion for Antarctic drilling fluid.

[0057] Example 7

[0058] A preparation method of a water-in-oil emulsion for Antarctic drilling fluid includes the following steps:

[0059] (1) Add anhydrous calcium chloride to water and stir for 6 min to prepare a brine solution; wherein, the addition amount of deionized water is 20 parts, and the mass of CaCl 2 is 30% of the mass of deionized water;

[0060] (2) Pour aviation kerosene into a pulp cup, and add Span-80 while stirring with a high-speed stirrer (rotation speed is 500 r / min), and stir for 15 min to make it fully dissolve to obtain a base liquid containing an emulsifier; wherein, the addition amount of aviation kerosene is 80 parts, and the addition amount of Span-80 is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0061] (3) Add the brine solution obtained in step (1) to the base liquid containing the emulsifier obtained in step (2), and stir for 25 min under the condition that the stirring rate is 6000 r / min to obtain a water-in-oil emulsion for Antarctic drilling fluid.

[0062] Comparative Example 1

[0063] A method for preparing a water-in-oil emulsion for Antarctic drilling fluid is as described in Example 1, except that: the dosage of sodium dodecylbenzenesulfonate in step (2) is 0.5%, and other steps and conditions are the same as those in Example 1.

[0064] Comparative Example 2

[0065] A method for preparing a water-in-oil emulsion for Antarctic drilling fluid is as described in Example 1, except that: the emulsifier in step (2) is changed from sodium dodecylbenzenesulfonate to sodium dodecyl sulfate, and other steps and conditions are the same as those in Example 1.

[0066] Comparative Example 3

[0067] A method for preparing a water-in-oil emulsion for Antarctic drilling fluid is as described in Example 1, except that: the drilling fluid base fluid in step (2) is changed from aviation kerosene to butyl acetate, and other steps and conditions are the same as those in Example 1.

[0068] Comparative Example 4

[0069] A method for preparing a water-in-oil emulsion for Antarctic drilling fluid is as described in Example 1, except that: the dosage of sodium dodecylbenzenesulfonate in step (2) is 4%, and other steps and conditions are the same as those in Example 1.

[0070] Comparative Example 5

[0071] A method for preparing a water-in-oil emulsion for Antarctic drilling fluid is as described in Example 1, except that: the mass of CaCl 2 in step (1) is 20% of the mass of deionized water, and other steps and conditions are the same as those in Example 1.

[0072] Comparative Example 6

[0073] A method for preparing a water-in-oil emulsion for Antarctic drilling fluid is as described in Example 1, except that: there are 95 parts of aviation kerosene and 5 parts of deionized water, and other steps and conditions are the same as those in Example 1.

[0074] Comparative Example 7

[0075] A method for preparing a water-in-oil emulsion for Antarctic drilling fluid is as described in Example 1, except that: the inorganic salt is changed from CaCl 2 to KCl, and other steps and conditions are the same as those in Example 1.

[0076] Test Example 1

[0077] Perform performance tests on the water-in-oil emulsions for Antarctic drilling fluid prepared in Examples 1-7 and Comparative Examples 1-7 at -35°C. The experimental results are shown in Table 1:

[0078] (1) Test method:

[0079] Emulsion stability test: The prepared emulsion was filled into a colorimetric tube and frozen at -35°C for 16 h. Subsequently, the volume of the oil separated on the upper layer of the emulsion at different times was recorded (V 2 ). Calculate the emulsion efficiency according to (V 1 - V 2 ) / V 1 ×100%, where V 1 is the total volume of the emulsion, in mL; V 2 is the volume of the oil separated on the upper layer of the emulsion, in mL.

[0080] Interfacial tension test: First, according to the formulations of each example and comparative example, the base liquid containing the emulsifier was used as the low-density phase, and the brine solution was used as the high-density phase. Second, freeze them at -35°C for 16 h respectively, and then add the above two phases into the experimental apparatus in sequence according to the program requirements of the interfacial tensiometer, and measure the interfacial tension between the two phases by the hanging plate method. Test instrument: DCAT21 interfacial tension measuring instrument; Manufacturer: Dataphysics Company, Germany.

[0081] Rheology test: Pour the prepared drilling fluid into the test slurry cup, and use a low-temperature rheometer to measure at 600 r and 300 r at -35°C, and then calculate the relevant rheological parameters, such as apparent viscosity, plastic viscosity, and dynamic shear force.

[0082] Table 1 Performance test of water-in-oil emulsion at -35°C

[0083]

[0084]

[0085] It can be seen from the data in Table 1 that the water-in-oil emulsion prepared by the present invention shows good emulsion stability at -35°C, with a low oil-water interfacial tension. At the same time, the drilling fluid has a significant effect on increasing the shear force under ultra-low temperature conditions. The emulsion efficiency at -35°C reaches more than 79.8%, the oil-water interfacial tension reaches below 5.7 mN / m, and the dynamic shear force of the emulsion at -35°C can reach above 2.0 Pa. It shows that the emulsion has excellent comprehensive performance under ultra-low temperature conditions and can meet the technical requirements of polar drilling.

[0086] In summary, the water-in-oil emulsion for Antarctic drilling fluid of the present invention can meet the needs of polar drilling.

[0087] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0088] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination manners.

[0089] Furthermore, any combination can be made among various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A water-in-oil emulsion for Antarctic drilling fluid, characterized in that: The emulsion is prepared from a drilling fluid base fluid, water, an inorganic salt and an emulsifier; the drilling fluid base fluid is one of aviation kerosene or isododecane; the inorganic salt is CaCl2 and / or NaCl; the emulsifier is one of sodium dodecylbenzene sulfonate, Span-80, Tween-60 or a combination of two or more thereof.

2. The water-in-oil emulsion for Antarctic drilling fluid according to claim 1, characterized in that: The drilling fluid base fluid is aviation kerosene; the inorganic salt is CaCl2; and the emulsifier is sodium dodecylbenzene sulfonate.

3. The water-in-oil emulsion for Antarctic drilling fluid according to claim 1, characterized in that: The volume ratio of drilling fluid base fluid to water in the Antarctic drilling fluid oil-in-water emulsion is 80-90:10-20; the mass of the inorganic salt is 25-35% of the mass of water; and the mass of the emulsifier is 1-3% of the total mass of the drilling fluid base fluid, water and inorganic salt.

4. A method for preparing the water-in-oil emulsion for Antarctic drilling fluid according to any one of claims 1 to 3, comprising the following steps: (1) adding an inorganic salt to water and stirring uniformly to obtain a saline solution; (2) adding an emulsifier to a drilling fluid base fluid and stirring the base fluid to dissolve the emulsifier to obtain a base fluid containing the emulsifier; (3) Adding the brine solution obtained in step (1) to the base liquid containing the emulsifier obtained in step (2), stirring evenly, to obtain an oil-in-water emulsion for Antarctic drilling fluid.

5. The method for preparing the water-in-oil emulsion for Antarctic drilling fluid according to claim 4, characterized in that: The mass of the inorganic salt in step (1) is 25-35% of the mass of deionized water; The volume ratio of the drilling fluid base fluid to the water in step (1) is 80-90:10-20; The mass of the emulsifier is 1 to 3% of the total mass of the drilling fluid base fluid, water, and inorganic salt; The stirring speed is 5000-8000 r / min, and the stirring time is 20-30 min.

6. The Antarctic water-in-oil emulsion for drilling fluid according to any one of claims 1 to 3 is used in polar formations as a drilling fluid for drilling in polar formations; preferably, the polar region is Antarctica.

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