A water-in-oil emulsion for antarctic drilling fluid and a preparation method and application thereof

Abstract

The application provides a water-in-oil emulsion for Antarctic drilling fluid and a preparation method and application thereof. The water-in-oil emulsion for Antarctic drilling fluid is prepared from drilling fluid base fluid, water, inorganic salt and emulsifier; the drilling fluid base fluid is one of aviation kerosene or isododecane; the inorganic salt is CaCl2 and / or NaCl; and the emulsifier is one or a combination of two or more of sodium dodecyl benzene sulfonate, Span-80 and Tween-60. The water-in-oil emulsion for Antarctic drilling fluid has excellent emulsification and rheological properties and can resist ultra-low temperature of-35 DEG C. The problems of poor emulsion stability, difficult rock carrying and poor suspensibility of drilling fluid in the process of polar drilling can be solved. In addition, compared with Antarctic pure oil-based drilling fluid, the emulsion also has the advantage of low cost.

Description

TECHNICAL FIELD

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

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

[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 an anti-high-temperature fluid loss additive, its preparation method and oil-based drilling fluid, wherein a white oil-based basic emulsion is prepared, the main components of which include: 75% white oil + 12% CaCl2 solution + 4% main emulsifier + 2% auxiliary emulsifier + 2% organic clay + 5% CaO. Studies have shown that the dynamic shear force of the emulsion is 2.04 Pa, and the emulsion voltage is 425 V. Chinese patent document CN111793479A discloses an oil-based drilling fluid and its preparation method, wherein a water-based epoxy resin emulsion is prepared, the main components of which include: bisphenol F type epoxy resin, sodium dodecyl benzene sulfonate, deionized water and ethylene glycol monobutyl ether. The dynamic shear force of the emulsion can reach 5.0 Pa or more, and the emulsion voltage is 1000 V or more. Chinese patent document CN110003865A discloses an oil-in-water emulsion, its preparation method and oil-based drilling fluid. The water-in-oil emulsion includes an oil phase, a water phase and a hydrophobically modified fumed silica. Studies have found that the average particle size of the emulsion is basically unchanged after 6 months of storage, indicating that the emulsion has good stability. However, there is no relevant report on the research of ultra-low temperature drilling fluid emulsion suitable for Antarctic area.

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

[0005] In view of the deficiencies of the prior art, the present application provides a water-in-oil emulsion for Antarctic drilling fluid and its preparation method and application. The water-in-oil emulsion for Antarctic drilling fluid of the present application has excellent emulsifying property and rheological performance, and can withstand ultra-low temperature of-35℃. It can solve the problems of poor stability, difficult rock carrying and poor suspensibility of the drilling fluid emulsion in polar drilling process. In addition, compared with the pure oil-based drilling fluid in Antarctic area, the emulsion also has the advantage of low cost.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] The application discloses a water-in-oil emulsion for an Antarctic drilling fluid, which is prepared from a drilling fluid base fluid, water, inorganic salt and emulsifier; the drilling fluid base fluid is one of aviation kerosene or isododecane; the inorganic salt is CaCl2 and / or NaCl; and the emulsifier is one of sodium dodecyl benzene sulfonate, Span-80 and Tween-60 or a combination of two or more thereof.

[0008] According to the application, preferably, the drilling fluid base fluid is aviation kerosene; the inorganic salt is CaCl2; and the emulsifier is sodium dodecyl benzene sulfonate.

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

[0010] According to the application, the preparation method of the water-in-oil emulsion for the Antarctic drilling fluid comprises the following steps:

[0011] (1) adding inorganic salt into water and stirring uniformly to obtain a salt water solution;

[0012] (2) adding emulsifier into the drilling fluid base fluid and stirring to dissolve the emulsifier, so as to obtain a base fluid containing emulsifier;

[0013] (3) adding the salt water solution obtained in step (1) into the base fluid containing emulsifier obtained in step (2) and stirring uniformly, so as to obtain the water-in-oil emulsion for the Antarctic drilling fluid.

[0014] According to the application, preferably, the mass of the inorganic salt in step (1) is 25-35% of the mass of the deionized water.

[0015] According to the application, preferably, the volume ratio of the drilling fluid base fluid in step (2) to the volume of water in step (1) is 80-90:10-20.

[0016] According to the application, preferably, the mass of the emulsifier in step (2) is 1-3% of the total mass of the drilling fluid base fluid, water and inorganic salt.

[0017] According to the application, preferably, the stirring speed in step (3) is 5000-8000 r / min, and the stirring time is 20-30 min.

[0018] According to the application, the water-in-oil emulsion for the Antarctic drilling fluid is applied in a polar stratum and is used for drilling in the polar stratum as a drilling fluid; preferably, the polar stratum is the South Pole.

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

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

[0021] 2、The water-in-oil emulsion of the present application has high emulsification rate and low interfacial tension under super-low temperature conditions, and has excellent long-term stability, with an emulsification rate of more than 79.8% after being frozen for 16h.

[0022] 3、The water-in-oil emulsion of the present application has excellent rheological properties under super-low temperature conditions, with a dynamic shear force of more than 2.0Pa at -35℃, and a low plastic viscosity, which can meet the needs of Antarctic drilling; and, in the present application, too much or too little emulsifier, or changes in the type of emulsifier, will reduce the adsorption amount at the emulsion interfacial film, thereby reducing the interfacial film strength of the emulsion and resulting in poor effects; at the same time, the type of inorganic salt also has an important influence, and in the presence of specific CaCl2 or NaCl in the present application, the emulsion has high emulsification rate, while replacing KCl, there will be a precipitation phenomenon in the emulsion under super-low temperature conditions, affecting the performance of the emulsion; in addition, too high oil-water ratio will result in a low strength of the network structure formed between the water droplets at the oil-water interface and the emulsifier, thereby resulting in poor emulsion stability.

[0023] 4、The water-in-oil emulsion of the present application has excellent emulsion stability and rheological properties under super-low temperature conditions, because the emulsifier is adsorbed at the oil-water interface through hydrogen bonding, electrostatic attraction, and interaction between carbon chains, etc., significantly improving the strength of the oil-water interfacial film, and thereby making the emulsion have long-term stability. In addition, the network structure formed by this action also significantly improves the dynamic shear force of the emulsion, improving its rheological properties. In summary, the obtained water-in-oil emulsion has excellent comprehensive performance, providing technical support for polar super-low temperature drilling engineering, and has broad application prospects. DETAILED DESCRIPTION

[0024] The present application will be further described below through specific examples, but is not limited thereto.

[0025] In the examples, the experimental methods are conventional methods unless otherwise specified; and the reagents and materials used are commercially available unless otherwise specified.

[0026] In the examples, the "parts" 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) adding anhydrous calcium chloride into water, stirring for 6 min to prepare a brine solution; wherein, the amount of deionized water is 20 parts, and the mass of CaCl2 is 30% of the mass of deionized water;

[0030] (2) pouring aviation kerosene into a slurry cup, adding sodium dodecyl benzene sulfonate while stirring at a high-speed stirrer (500 r / min), stirring for 15 min to make it fully dissolved, to obtain a base liquid containing an emulsifier; wherein, the amount of aviation kerosene is 80 parts, and the amount of sodium dodecyl benzene sulfonate is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0031] (3) adding the brine solution obtained in step (1) into the base liquid containing an emulsifier obtained in step (2), stirring for 25 min at a stirring rate of 6000 r / min, to obtain an oil-in-water emulsion for Antarctic drilling fluid.

[0032] Example 2

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

[0034] (1) adding anhydrous calcium chloride into water, stirring for 6 min to prepare a brine solution; wherein, the amount of deionized water is 20 parts, and the mass of CaCl2 is 30% of the mass of deionized water;

[0035] (2) pouring aviation kerosene into a slurry cup, adding sodium dodecyl benzene sulfonate while stirring at a high-speed stirrer (500 r / min), stirring for 15 min to make it fully dissolved, to obtain a base liquid containing an emulsifier; wherein, the amount of aviation kerosene is 80 parts, and the amount of sodium dodecyl benzene sulfonate is 1.5% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0036] (3) adding the brine solution obtained in step (1) into the base liquid containing an emulsifier obtained in step (2), stirring for 25 min at a stirring rate of 6000 r / min, to obtain an oil-in-water emulsion for Antarctic drilling fluid.

[0037] Example 3

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

[0039] (1) adding anhydrous calcium chloride into water, stirring for 6 min to prepare a brine solution; wherein, the amount of deionized water is 15 parts, and the mass of CaCl2 is 30% of the mass of deionized water;

[0040] (2) Pour the aviation kerosene into the slurry cup, and add sodium dodecyl benzene sulfonate while stirring at high speed (500 r / min), and stir for 15 min to make it fully dissolved to obtain a base liquid containing emulsifier; wherein, the amount of aviation kerosene is 85 parts, and the amount of sodium dodecyl benzene sulfonate is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0041] (3) Add the salt water solution obtained in step (1) to the base liquid containing emulsifier obtained in step (2), and stir at a stirring rate of 6000 r / min for 25 min to obtain the 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, comprising the following steps:

[0044] (1) Add anhydrous calcium chloride to water and stir for 6 min to prepare a salt water solution; wherein, the amount of deionized water is 20 parts, and the mass of CaCl2 is 35% of the mass of deionized water;

[0045] (2) Pour the aviation kerosene into the slurry cup, and add sodium dodecyl benzene sulfonate while stirring at high speed (500 r / min), and stir for 15 min to make it fully dissolved to obtain a base liquid containing emulsifier; wherein, the amount of aviation kerosene is 80 parts, and the amount of sodium dodecyl benzene sulfonate is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0046] (3) Add the salt water solution obtained in step (1) to the base liquid containing emulsifier obtained in step (2), and stir at a stirring rate of 6000 r / min for 25 min to obtain the 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, comprising the following steps:

[0049] (1) Add anhydrous sodium chloride to water and stir for 6 min to prepare a salt water solution; wherein, the 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 slurry cup, and add sodium dodecyl benzene sulfonate while stirring at high speed (500 r / min), and stir for 15 min to make it fully dissolved to obtain a base liquid containing emulsifier; wherein, the amount of aviation kerosene is 80 parts, and the amount of sodium dodecyl benzene sulfonate is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0051] (3) The salt water solution obtained in step (1) is added to the base fluid containing emulsifier obtained in step (2), and stirred at a stirring rate of 6000 r / min for 25 min to obtain the 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, comprising the following steps:

[0054] (1) Anhydrous calcium chloride is added to water, and stirred for 6 min to prepare a salt water solution; wherein the amount of deionized water is 20 parts, and the mass of CaCl2 is 30% of the mass of deionized water;

[0055] (2) Isododecane (CAS No.: 31807-55-3) is poured into a slurry cup, and sodium dodecyl benzene sulfonate is added while stirring at a high speed (500 r / min), and stirred for 15 min to fully dissolve, to obtain a base fluid containing emulsifier; wherein the amount of isododecane is 80 parts, and the amount of sodium dodecyl benzene sulfonate is 2% of the total mass of isododecane, water and anhydrous calcium chloride;

[0056] (3) The salt water solution obtained in step (1) is added to the base fluid containing emulsifier obtained in step (2), and stirred at a stirring rate of 6000 r / min for 25 min to obtain the 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, comprising the following steps:

[0059] (1) Anhydrous calcium chloride is added to water, and stirred for 6 min to prepare a salt water solution; wherein the amount of deionized water is 20 parts, and the mass of CaCl2 is 30% of the mass of deionized water;

[0060] (2) Aviation kerosene is poured into a slurry cup, and Span-80 is added while stirring at a high speed (500 r / min), and stirred for 15 min to fully dissolve, to obtain a base fluid containing emulsifier; wherein the amount of aviation kerosene is 80 parts, and the amount of Span-80 is 2% of the total mass of aviation kerosene, water and anhydrous calcium chloride;

[0061] (3) The salt water solution obtained in step (1) is added to the base fluid containing emulsifier obtained in step (2), and stirred at a stirring rate of 6000 r / min for 25 min to obtain the water-in-oil emulsion for Antarctic drilling fluid.

[0062] Comparative Example 1

[0063] A preparation method of the water-in-oil emulsion for Antarctic drilling fluid is as described in Embodiment 1, except that the amount of sodium dodecyl benzene sulfonate in step (2) is 0.5%, and other steps and conditions are the same as in Embodiment 1.

[0064] Comparative Example 2

[0065] A preparation method of the water-in-oil emulsion for Antarctic drilling fluid is as described in Embodiment 1, except that the emulsifier in step (2) is changed from sodium dodecyl benzene sulfonate to sodium dodecyl sulfate, and other steps and conditions are the same as in Embodiment 1.

[0066] Comparative Example 3

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

[0068] Comparative Example 4

[0069] A preparation method of the water-in-oil emulsion for Antarctic drilling fluid is as described in Embodiment 1, except that the amount of sodium dodecyl benzene sulfonate in step (2) is 4%, and other steps and conditions are the same as in Embodiment 1.

[0070] Comparative Example 5

[0071] A preparation method of the water-in-oil emulsion for Antarctic drilling fluid is as described in Embodiment 1, except that the mass of CaCl2 in step (1) is 20% of the mass of deionized water, and other steps and conditions are the same as in Embodiment 1.

[0072] Comparative Example 6

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

[0074] Comparative Example 7

[0075] A preparation method of the water-in-oil emulsion for Antarctic drilling fluid is as described in Embodiment 1, except that the inorganic salt is changed from CaCl2 to KCl, and other steps and conditions are the same as in Embodiment 1.

[0076] Test Example 1

[0077] The water-in-oil emulsions for Antarctic drilling fluid prepared in Examples 1-7 and Comparative Examples 1-7 are tested for performance under conditions of -35°C, and the experimental results are shown in Table 1.

[0078] (1) Test method:

[0079] Emulsification rate test: the prepared emulsion was filled into a colorimetric tube, frozen at-35℃ for 16h, and then the volume of oil separated from the upper layer of the emulsion (V2) was recorded at different times. The emulsification efficiency was calculated as (V1-V2) / V1*100%, wherein V1 was the total volume of the emulsion, mL; and V2 was the volume of oil separated from the upper layer of the emulsion, mL.

[0080] Interfacial tension test: first, the base fluid containing the emulsifier was used as the low-density phase, and the salt solution was used as the high-density phase according to the proportions of the respective examples and the comparative examples. Second, they were each frozen at-35℃ for 16h, and then the two phases were sequentially added into the experimental apparatus according to the program requirements of the interfacial tension meter, and the interfacial tension of the two phases was tested by the hanging piece method. Test instrument: DCAT21 interfacial tension meter; manufacturer: Dataphysics Company, Germany.

[0081] Rheological property test: the prepared drilling fluid was poured into a test slurry cup, and a low-temperature rheometer was used to test 600r and 300r at-35℃, and then relevant rheological parameters such as apparent viscosity, plastic viscosity and dynamic shear force were calculated.

[0082] Table 1 Performance test of the water-in-oil emulsion at-35℃

[0083]

[0084]

[0085] As can be seen from the data in Table 1, the water-in-oil emulsion prepared by the present application exhibits good emulsion stability at-35℃, and the oil-water interfacial tension is low. Meanwhile, the lifting effect of the drilling fluid under the condition of ultra-low temperature is remarkable. The emulsification rate of the emulsion at-35℃ is more than 79.8%, the oil-water interfacial tension is less than 5.7mN / m, and the dynamic shear force of the emulsion at-35℃ can be more than 2.0Pa. It is shown that the emulsion has excellent comprehensive performance under the condition of ultra-low temperature, and can meet the technical requirements of polar drilling.

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

[0087] The above describes the preferred embodiments of the present application, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0088] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not describe various possible combinations again.

[0089] Furthermore, the various embodiments can also be combined, if not in contradiction, as long as they do not deviate from the spirit of the present application, which should be considered as disclosed.

Claims

1. A water-in-oil emulsion for Antarctic drilling fluid used in polar formations, characterized in that, This Antarctic drilling fluid oil-in-water emulsion is prepared from drilling fluid base fluid, water, inorganic salts, and emulsifiers; the drilling fluid base fluid is either aviation kerosene or isododecane; the inorganic salts are CaCl2 and / or NaCl; and the emulsifiers are one or a combination of two or more of sodium dodecylbenzenesulfonate, Span-80, and Tween-60. The volume ratio of drilling fluid base fluid to water in the Antarctic drilling fluid 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 drilling fluid base fluid, water, and inorganic salt.

2. The application of the Antarctic drilling fluid oil-in-water emulsion according to claim 1 in polar formations, characterized in that, The drilling fluid base is aviation kerosene; the inorganic salt is CaCl2; and the emulsifier is sodium dodecylbenzenesulfonate.

3. The application of the Antarctic drilling fluid oil-in-water emulsion according to claim 1 in polar formations, characterized in that, The method for preparing the water-in-oil emulsion for Antarctic drilling fluid includes the following steps: (1) Add inorganic salt to water and stir well to obtain a salt solution; (2) Add emulsifier to drilling fluid base fluid and stir to dissolve it to obtain base fluid containing emulsifier; (3) Add the brine solution obtained in step (1) to the base liquid containing emulsifier obtained in step (2), stir evenly, and obtain the water-in-oil emulsion for Antarctic drilling fluid.

4. The application of the Antarctic drilling fluid oil-in-water emulsion according to claim 3 in polar formations, characterized in that, The mass of the inorganic salt mentioned in step (1) is 25-35% of the mass of the 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 1-3% of the total mass of drilling fluid base fluid, water, and inorganic salts; The stirring speed is 5000~8000 r / min, and the stirring time is 20~30 min.

5. The application of the Antarctic drilling fluid oil-in-water emulsion according to claim 1 in polar formations, characterized in that, The polar region mentioned is Antarctica.

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