Phase change material for oil-based drilling fluids, method for its preparation and use

Abstract

The present application relates to a kind of oil-based drilling fluid phase change materials and its preparation method and use, to solve the phase change latent heat low, the phase change point low and preparation process complex, preparation cost high problem of phase change material for oil-based drilling fluid.The oil-based drilling fluid phase change material provided by the present application, by the component of phase change material is designed, utilize the synergistic effect between each component, enhance the phase change latent heat index and heat transfer effect of obtained phase change material, while ensuring that can realize and oil-based drilling fluid has good compatibility effect, does not affect the performance embodiment of drilling fluid.

Description

Technical Field

[0001] This invention relates to oil drilling applications, specifically to a phase change material for oil-based drilling fluids, its preparation method, and its uses. Background Technology

[0002] Currently, in deep oil and gas drilling and development, drilling tools, measurement-while-drilling (MWD) instruments, and logging instruments experience short lifespans and high failure rates under high-temperature environments. Extensive field drilling data shows that in wells with downhole temperatures exceeding 150°C, the failure rate of rotary steerable, geosteering, and directional drilling tools remains consistently high. Traditional drilling fluid cooling methods utilize surface cooling equipment to lower the temperature of high-temperature drilling fluids, and while widely used in geothermal wells, hydrate drilling, and shale gas horizontal wells, these methods suffer from poor reliability and high energy consumption.

[0003] Therefore, research on the application of phase change materials in drilling fluids is gradually increasing in the existing technology. For example, CN112358852A discloses a phase change microcapsule, its preparation method, and an intelligent temperature-controlled water-based drilling fluid and its application. The phase change microcapsule includes a core material and a wall material covering the outer surface of the core material. The wall material also contains an optional wall material reinforcing agent. The core material is selected from one or more of n-tetradecane, dodecanol, decanol, and octanoic acid; the wall material is urea-formaldehyde resin and / or melamine-formaldehyde resin; and the wall material reinforcing agent is manganese tetroxide. This intelligent temperature-controlled water-based drilling fluid can intelligently regulate the downhole drilling fluid temperature and avoid hydrate decomposition caused by increased drilling fluid temperature.

[0004] For example, CN111894520A discloses a method for regulating drilling fluid temperature based on paraffin materials. The basic technical solution is as follows: (1) synthesizing and selecting paraffin materials suitable for drilling fluid applications; (2) using paraffin materials as drilling fluid treatment agents, maintaining an addition amount of 5%-20% to reduce temperature by 5-15℃; (3) using methods such as microencapsulation for material reuse. The advantages of this solution are: during drilling fluid circulation, paraffin undergoes a phase change, and the latent heat of this phase change can fully absorb heat; when the drilling fluid circulates to the surface, as the temperature decreases, the paraffin will re-solidify and release heat, eliminating the need for external cooling media.

[0005] For example, CN111545142A discloses a high-temperature phase change isothermal microcapsule, an actively temperature-controlled high-temperature drilling fluid system, and their preparation and application. The core material of the microcapsule is modified paraffin wax modified with polyethylene and / or styrene-butadiene-styrene triblock copolymer, and the wall material of the microcapsule is urea-formaldehyde resin. When the temperature rises, the phase change material undergoes a phase change. The temperature range of the phase change is very narrow, and the temperature of the material itself remains almost constant before and after the phase change. When a large amount of phase change heat is transferred to the environment, a relatively wide temperature plateau is generated. The phase change isothermal microcapsule of the present invention has a phase change temperature of up to 110-140℃ and a latent heat of phase change of up to 100-150 J / g, and possesses good thermal conductivity and thermal stability.

[0006] For example, CN109652028A discloses a drilling fluid temperature control method based on phase change materials. The technical solution includes the following steps: (1) Selecting a phase change material for drilling fluid; (2) Using the phase change material as a drilling fluid treatment agent, it can be added before weighting when preparing the drilling fluid, with an addition amount of 5%-15% of the total weight of the drilling fluid; or it can be added at a concentration of 5-15 kg per cubic meter of drilling fluid during drilling. After circulation and uniformity, drilling can proceed. The concentration of the added phase change material varies depending on the bottom hole temperature, until the required drilling fluid circulation temperature is reached, not exceeding 20% ​​of the total weight of the drilling fluid; (3) After drilling is completed, the phase change material can be recycled and reused. The beneficial effects are: during the drilling fluid circulation process, the phase change material can continuously absorb and release an appropriate amount of heat energy; the phase change material can be used in circulation with other drilling fluid treatment agents; it is maintenance-free; it does not require electricity and is environmentally friendly; and it is competitive in terms of economic benefits.

[0007] However, most phase change materials currently used in drilling fluids are phase change microcapsule materials, which still have problems such as low latent heat of phase change, low phase change point, complex preparation process, and high preparation cost. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a phase change material for oil-based drilling fluids, its preparation method and application, so as to solve the problems of low latent heat of phase change, low phase change point, complex preparation process and high preparation cost of phase change materials used in oil-based drilling fluids.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a phase change material for oil-based drilling fluids, the phase change material comprising: tris(hydroxymethyl)aminomethane, tris(hydroxymethyl)ethane, graphite, rubber, and asphalt.

[0011] The phase change material for oil-based drilling fluid provided by this invention enhances the latent heat of phase change and heat transfer effect of the obtained phase change material by designing the components and utilizing the synergistic effect between the components. At the same time, it ensures that it can achieve good compatibility with oil-based drilling fluid without affecting the performance of the drilling fluid.

[0012] As a preferred technical solution of the present invention, the phase change material for oil-based drilling fluid comprises, by weight, 80-90 parts of tris(hydroxymethyl)aminomethane, 1-5 parts of tris(hydroxymethyl)ethane, 1-7 parts of graphite, 1-3 parts of rubber, and 1-3 parts of asphalt.

[0013] As a preferred embodiment of the present invention, the graphite includes expanded graphite.

[0014] As a preferred embodiment of the present invention, the rubber includes natural rubber and / or styrene-butadiene rubber.

[0015] As a preferred embodiment of the present invention, the asphalt includes oxidized asphalt and / or natural asphalt.

[0016] In a second aspect, the present invention provides a method for preparing a phase change material for oil-based drilling fluid as described in the first aspect. The preparation method includes: melting tris(hydroxymethyl)aminomethane and tris(hydroxymethyl)ethane according to a formula, then adding graphite, rubber and asphalt and stirring, and then cooling and crushing and sieving to obtain the phase change material for oil-based drilling fluid.

[0017] As a preferred embodiment of the present invention, the melting temperature is 200-250℃.

[0018] As a preferred embodiment of the present invention, the stirring rate is 250-350 r / min;

[0019] Preferably, the stirring time is 2-3 hours.

[0020] Thirdly, the present invention provides a use of the phase change material for oil-based drilling fluid as described in the first aspect, the use including mixing the phase change material for oil-based drilling fluid with oil-based drilling fluid to regulate the temperature of the drilling fluid.

[0021] As a preferred embodiment of the present invention, the amount of phase change material added to the oil-based drilling fluid is ≤ 12% of the volume of the oil-based drilling fluid.

[0022] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0023] (1) In view of the high failure rate of tools and instruments such as rotary steering, geological steering tools and directional instruments caused by high temperature during deep well drilling, and the immature existing drilling fluid cooling technology, which cannot meet the safe and efficient drilling requirements of high temperature wells, this invention provides a phase change material for oil-based drilling fluid. The latent heat of phase change of this phase change material can be ≥251.37J / g and the phase change temperature can reach ≥127.88℃.

[0024] (2) This invention utilizes the combined effect of expanded graphite, rubber and asphalt to improve the thermal conductivity of phase change materials, has good compatibility in oil-based drilling fluids, has little impact on rheological properties, and has a good effect on reducing filtration loss.

[0025] (3) The present invention has a simple on-site process, especially for deep wells drilled using oil-based drilling fluid, which will not delay the construction cycle; it does not require additional equipment or energy consumption, and can be recycled and reused to improve the efficiency of oil and gas field development; it can meet the drilling construction needs of high temperature and high density deep wells. Attached Figure Description

[0026] Figure 1 This is a DSC differential scanning calorimetry test diagram of the phase change material for oil-based drilling fluid obtained in Example 7 of the present invention.

[0027] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0028] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0029] This embodiment provides a phase change material for oil-based drilling fluids, which includes: tris(hydroxymethyl)aminomethane, tris(hydroxymethyl)ethane, graphite, rubber, and asphalt.

[0030] Specifically, the phase change material for the oil-based drilling fluid comprises, by weight, 80-90 parts of tris(hydroxymethyl)aminomethane, 1-5 parts of tris(hydroxymethyl)ethane, 1-7 parts of graphite, 1-3 parts of rubber, and 1-3 parts of asphalt.

[0031] In this invention, controlling the tris(hydroxymethyl)aminomethane, tris(hydroxymethyl)ethane, graphite, rubber, and asphalt in the phase change material for oil-based drilling fluid to a specific weight ratio helps ensure that the phase change material has a high phase change temperature and latent heat of phase change, while also possessing good thermal conductivity. Furthermore, it ensures good compatibility between the phase change material and the oil-based drilling fluid, such as reducing filtration loss.

[0032] The tris(hydroxymethyl)aminomethane in the phase change material for oil-based drilling fluid is 80-90 parts by weight, for example, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89 or 90 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] The trimethylolethane in the phase change material for oil-based drilling fluid is 1-5 parts by weight, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] The graphite in the phase change material for oil-based drilling fluid is 1-7 parts by weight, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts or 7 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] The rubber in the phase change material for oil-based drilling fluid is 1-3 parts by weight, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] The asphalt in the phase change material for oil-based drilling fluid is 1-3 parts by weight, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Specifically, the graphite includes expanded graphite, which is a loose, porous, worm-like material obtained from natural flake graphite. The preparation process can include concentrated sulfuric acid method, mixed acid method, secondary oxidation method, electrochemical oxidation method, or gas-phase diffusion method, etc. The expanded graphite has a well-developed porous structure and a fixed carbon content ≥98%.

[0038] Specifically, the rubber includes natural rubber and / or styrene-butadiene rubber; ensuring that the median particle size of the rubber in the material is ≤25 micrometers.

[0039] Specifically, the asphalt includes oxidized asphalt and / or natural asphalt; during the selection process, it is sufficient to ensure that the softening point of the asphalt is 120-150℃.

[0040] Furthermore, this embodiment provides a preparation process for the above-mentioned phase change material for oil-based drilling fluid, including: melting tris(hydroxymethyl)aminomethane and tris(hydroxymethyl)ethane according to the formula, then adding graphite, rubber and asphalt and stirring, and then cooling and crushing and sieving to obtain the phase change material for oil-based drilling fluid.

[0041] Specifically, the melting temperature is 200-250℃, for example, it can be 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Specifically, the stirring rate is 250-350 r / min, for example, it can be 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min, 300 r / min, 310 r / min, 320 r / min, 330 r / min, 340 r / min or 350 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0043] Specifically, the stirring time is 2-3 hours, for example, it can be 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Furthermore, the amount of phase change material added to the oil-based drilling fluid is selected based on the temperature in the well. For example, it can be selected as ≤12% of the volume of the oil-based drilling fluid, such as 12%, 11%, 10%, 9%, 8%, 7%, 6%, or 5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Based on the foregoing embodiments, the present invention provides the following specific embodiments. All reagents used in the embodiments are commercially available reagents. For example, the tris(hydroxymethyl)aminomethane used was purchased from Sinopharm Chemical Reagent Co., Ltd.; the tris(hydroxymethyl)ethane used was purchased from Sinopharm Chemical Reagent Co., Ltd.; the expanded graphite used was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a fixed carbon content of 99%; the asphalt used was purchased from Shandong Deshunyuan Petroleum Technology Co., Ltd., with a softening point of 130℃; and the rubber used was purchased from Shaanxi Yanchang Petroleum Northwest Rubber Co., Ltd., with a median particle size of 25μm.

[0046] Example 1

[0047] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0048] 80g of tris(hydroxymethyl)aminomethane and 5g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 200℃ and allowed to melt. Then, 5g of expanded graphite, 3g of asphalt, and 2g of rubber were added, and the mixture was stirred for 2 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-1, a phase change material for oil-based drilling fluids.

[0049] Example 2

[0050] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0051] 85g of tris(hydroxymethyl)aminomethane and 2g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 200℃ and allowed to melt. Then, 5g of expanded graphite, 2g of asphalt, and 1g of rubber were added, and the mixture was stirred for 2 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-2, a phase change material for oil-based drilling fluids.

[0052] Example 3

[0053] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0054] 90g of tris(hydroxymethyl)aminomethane and 1g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 200℃ and allowed to melt. Then, 4g of expanded graphite, 2g of asphalt, and 3g of rubber were added, and the mixture was stirred for 2 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-3, a phase change material for oil-based drilling fluids.

[0055] Example 4

[0056] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0057] 90g of tris(hydroxymethyl)aminomethane and 4g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 200℃ and allowed to melt. Then, 1g of expanded graphite, 2g of asphalt, and 3g of rubber were added, and the mixture was stirred for 2 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-4, a phase change material for oil-based drilling fluids.

[0058] Example 5

[0059] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0060] 90g of tris(hydroxymethyl)aminomethane and 4g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 200℃ and allowed to melt. Then, 4g of expanded graphite, 1g of asphalt, and 1g of rubber were added, and the mixture was stirred for 2 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-5, a phase change material for oil-based drilling fluids.

[0061] Example 6

[0062] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0063] 90g of tris(hydroxymethyl)aminomethane and 4g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 200℃ and allowed to melt. Then, 3g of expanded graphite, 2g of asphalt, and 1g of rubber were added, and the mixture was stirred for 2 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-6, a phase change material for oil-based drilling fluids.

[0064] Example 7

[0065] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0066] 90g of tris(hydroxymethyl)aminomethane and 1g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 200℃ and allowed to melt. Then, 7g of expanded graphite, 1g of asphalt, and 1g of rubber were added, and the mixture was stirred for 2 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-7, a phase change material for oil-based drilling fluids. The DSC differential scanning calorimetry (DSC) chart of the obtained phase change material for oil-based drilling fluids is detailed below. Figure 1 .

[0067] Example 8

[0068] This embodiment provides a phase change material for oil-based drilling fluids, which is prepared by the following method:

[0069] 90g of tris(hydroxymethyl)aminomethane and 1g of tris(hydroxymethyl)ethane were added to a three-necked flask and stirred continuously. The temperature was raised to 220℃ and allowed to melt. Then, 7g of expanded graphite, 1g of asphalt, and 1g of rubber were added, and the mixture was stirred for 3 hours until homogeneous. The cooled mixture was then pulverized and sieved to obtain PCM-8, a phase change material for oil-based drilling fluids.

[0070] Example 9

[0071] The only difference from Example 1 is that trimethylolethane is not added, and the resulting oil-based drilling fluid is designated as PCM-9.

[0072] Example 10

[0073] The only difference from Example 1 is that trimethylolethane is replaced with an equal amount of neopentyl glycol, and the resulting oil-based drilling fluid phase change material is designated as PCM-10.

[0074] Example 11

[0075] The only difference from Example 1 is that expanded graphite is replaced with an equal amount of graphene with a sheet diameter of 7 μm. The resulting oil-based drilling fluid phase change material is designated as PCM-11.

[0076] Example 12

[0077] The only difference from Example 1 is that expanded graphite is not added, and the resulting oil-based drilling fluid uses a phase change material called PCM-12.

[0078] Example 13

[0079] The only difference from Example 1 is that no rubber is added, and the resulting oil-based drilling fluid uses a phase change material called PCM-13.

[0080] Example 14

[0081] The only difference from Example 1 is that no asphalt is added, and the resulting oil-based drilling fluid uses a phase change material called PCM-14.

[0082] Example 15

[0083] The only difference from Example 1 is that the styrene-butadiene rubber is replaced with an equal amount of cis-butadiene rubber, and the resulting oil-based drilling fluid phase change material is designated as PCM-15.

[0084] Test case

[0085] This test case evaluates the performance of phase change materials for oil-based drilling fluids provided in Examples 1-15.

[0086] 1. Phase transition point and latent heat of phase transition

[0087] Test Samples 1-15: The phase change materials for oil-based drilling fluids provided in Examples 1-15 of this invention are used as test samples 1-15. The latent heat of phase change and phase change point were measured by differential scanning calorimetry (DSC), and the results are shown in Table 1.

[0088] As shown in Table 1, the maximum phase transition point for Test Examples 1-15 is 135.39℃, which meets the requirements for high-temperature wells with temperatures exceeding the phase transition point, and the maximum latent heat of phase transition is 278.38 J / g. Increasing the temperature to 220℃ has little impact on the performance of the phase change material; Test Example 7 is selected as the optimal preparation formula for the next test.

[0089] Table 1

[0090]

[0091]

[0092] 2. Impact on the properties of oil-based drilling fluids

[0093] Test sample 7 was added to an oil-based drilling fluid system, and its rheological properties were measured using a six-speed viscometer.

[0094] Oil-based drilling fluid slurry formulation: 240mL diesel oil + 3% primary emulsifier + 3% secondary emulsifier + 2% organic clay + 60mL 30% CaCl2 solution + 4% filtration loss reducer + 5% quicklime + barite, density 2.1g / cm³ 3 ;

[0095] During the test, the aging conditions were 150℃ for 16 hours.

[0096] The results are shown in Table 2. As can be seen from Table 2, when phase change material is added to oil-based drilling fluid, the demulsification voltage decreases, the viscosity and shear stress increase, and the filtration loss decreases slightly; when the volume percentage of phase change material does not exceed 10%, the performance of oil-based drilling fluid meets the requirements of on-site construction.

[0097] Table 2

[0098]

[0099] 3. Theoretical cooling calculation

[0100] According to the law of conservation of energy, the percentage increase in mass of phase change material is calculated as follows.

[0101]

[0102] In the formula, P represents the percentage of phase change material added, %;

[0103] m p The mass of PCM-1 is in kg;

[0104] m f The volume of drilling fluid is expressed in kg.

[0105] C m Specific heat of drilling fluid, kJ / (kg·℃);

[0106] ΔT m The value represents the change in drilling fluid temperature, expressed in °C.

[0107] C p PCM-7 specific heat;

[0108] ΔT p This refers to the temperature change of the phase change material.

[0109] ΔH is the latent heat of phase transition in PCM-7.

[0110] The bottom hole drilling fluid temperature is 160℃, the surface temperature is 60℃, and the specific heat of the drilling fluid is 2.67 kJ / (kg·℃); the latent heat of phase change of the phase change material is 278.38 kJ / kg, and the specific heat is 2.0 kJ / (kg·℃). The theoretical cooling calculation is shown in Table 3.

[0111] As shown in Table 3, when the amount of phase change material added is 12%, the bottom temperature decreases by about 21.5℃.

[0112] Table 3

[0113] 1 2 3.6 2 4 7.2 3 5 10.8 4 6 14.3 5 10 17.9 6 12 21.5

[0114] As can be seen from the results of the above embodiments, the phase change material for oil-based drilling fluid provided by the present invention, by designing the components of the phase change material and utilizing the synergistic effect between the components, enhances the latent heat index and heat transfer effect of the obtained phase change material, while ensuring that it can achieve good compatibility with oil-based drilling fluid and does not affect the performance of the drilling fluid.

[0115] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0116] 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 solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0117] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0118] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A phase change material for oil-based drilling fluids, characterized in that, The phase change material for the oil-based drilling fluid comprises, by weight, 80-90 parts of tris(hydroxymethyl)aminomethane, 1-5 parts of tris(hydroxymethyl)ethane, 1-7 parts of graphite, 1-3 parts of rubber, and 1-3 parts of asphalt. The graphite includes expanded graphite; The rubber includes natural rubber and / or styrene-butadiene rubber.

2. The phase change material for oil-based drilling fluid as described in claim 1, characterized in that, The asphalt includes oxidized asphalt and / or natural asphalt.

3. A method for preparing a phase change material for oil-based drilling fluid as described in claim 1 or 2, characterized in that, The preparation method includes: melting tris(hydroxymethyl)aminomethane and tris(hydroxymethyl)ethane according to the formula, then adding graphite, rubber and asphalt and stirring, and then cooling and crushing and screening to obtain phase change material for oil-based drilling fluid.

4. The preparation method according to claim 3, characterized in that, The melting temperature is 200-250℃.

5. The preparation method according to claim 3, characterized in that, The stirring rate is 250-350 r / min.

6. The preparation method according to claim 3, characterized in that, The stirring time is 2-3 hours.

7. The use of a phase change material for oil-based drilling fluid as described in claim 1 or 2, characterized in that, The applications include mixing oil-based drilling fluids with phase change materials to regulate the temperature of the drilling fluid.

8. The use as described in claim 7, characterized in that, The amount of phase change material added to the oil-based drilling fluid is ≤ 12% of the volume of the oil-based drilling fluid.

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