High-temperature-resistant natural plant-based surfactant for synthetic-based drilling fluid and preparation method thereof

Abstract

The application discloses a natural plant-based surfactant for high-temperature-resistant synthetic drilling fluid and a preparation method thereof. A raw material composition comprises natural organic matter, an acid-binding agent, N,N dimethylformamide and a compound containing a long-chain acyl chloride or amine-based monomer. The natural plant-based surfactant for high-temperature-resistant synthetic drilling fluid comprises a compound with a terpene cyclic skeleton, a lipophilic group and a hydrophilic group, wherein the molecular structure of the terpene cyclic skeleton has a stacking constant P greater than 1. The technical scheme of the application obtains a rigid surfactant based on a natural terpene polycyclic skeleton, controls the aggregation and self-assembly behavior of the surfactant at an oil-water interface, and makes the system easy to form a water-in-oil emulsion system. The surfactant can be protected at a high temperature, can still maintain good surface activity at a higher temperature, can maintain the use of the drilling fluid system in a deep reservoir, and thus the purposes of preventing well leakage pollution, well wall collapse and safe drilling are achieved.

Description

TECHNICAL FIELD

[0001] The application relates to a natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid and a preparation method, and belongs to the technical field of oilfield exploitation. BACKGROUND

[0002] With the increase of oil and gas resource drilling and mining efforts, oil and gas is buried deep, the reservoir temperature is high, and the drilling and mining difficulty is increased, which puts forward a series of challenges to the drilling fluid technology. Most drilling fluids are a water-oil-solid three-component system, forming an oil-in-water or water-in-oil structure emulsion, which is a thermodynamically unstable system. The surfactant is the basis of the stability of the system. At the same time, the main component of the dispersed phase in the drilling fluid system is barite, which is difficult to disperse and easy to aggregate and precipitate at high temperature. In view of the above problems, the surfactant is adsorbed on the oil-water interface of the synthetic-based drilling fluid in a directional manner, forming a firm interface film, reducing the interfacial tension, preventing the water phase dispersed in the oil from gathering into large droplets, stabilizing the emulsion, and forming a network structure with a certain strength on the interface with lipophilic colloidal substances such as organic clay, filtration reducers and plugging agents, to ensure the stability of the synthetic-based drilling fluid during use. However, under high-temperature drilling conditions, the molecular motion of the surfactant is active, the connection bond with small bond energy in the molecule is easy to break, the intermolecular interaction force is reduced, the hydrogen bond interaction between molecules is destroyed, the surfactant loses the emulsifying ability, and even the demulsification phenomenon occurs, which cannot suspend the barite. Not only will it affect the drilling efficiency, but also will affect the wellbore stability, which will greatly increase the risk of drilling accidents. Traditional surfactants often have certain pollution to the environment, are expensive, and therefore it is of great significance to find a natural plant surfactant which is degradable, safe and environmentally friendly.

[0003] In the prior art, an amide-based primary and secondary emulsifier is used, and the emulsification rate of the synthetic-based drilling fluid reaches 83% under the conditions of an addition amount of 2% and a high temperature of 220 DEG C. In another prior art, an oligomeric amide surfactant is synthesized by using organic acid and organic amine as raw materials, and is used as a synthetic-based drilling fluid emulsifier. The emulsification rate is still greater than 90% at a high temperature of 220 DEG C, and the rheological property is excellent. The organic amide emulsifier has simple synthesis process, strong emulsification performance, and high temperature resistance, and has good application prospect as a surfactant for synthetic-based drilling fluid. In addition, it has been found that the synthetic-based drilling fluid surfactant with carboxylic acid as the end group and in the form of carboxylate anion in the polyester usually has good rheological property of the drilling fluid.

[0004] Natural terpene resources are important forestry characteristic biomass resources in China, which are rich in sources, low in price, good in biocompatibility and easy to degrade. Terpenes usually contain cyclic skeleton, and are carbon-containing organic substances with stable structure, and usually contain double bond, hydroxyl, amino and carboxylic acid and other chemical modification site structure advantages. Natural terpene materials containing rich hydrophilic groups can be used as excellent surfactants, such as saponins, but such compounds have certain limitations in high temperature resistance due to condensation with polysaccharides. Pure natural terpene compounds, such as rosin, have weak hydrophilicity of hydrophilic carboxylic acid, and the surface activity of the raw material itself is poor, but after modification of the chemical site, surfactants containing amide, carboxylic acid and other multi-hydrophilic groups can be developed. It can be well combined with hydrated groups to wrap clay particles to prevent well leakage and maintain well stability, but its high temperature resistance is poor. With the increase of oil and gas drilling intensity, oil and gas is buried deep, and the reservoir temperature is high. The surfactant is easily degraded, which destroys the stability of the system, so it is necessary to chemically modify the surfactant extracted from natural plants to improve the high temperature resistance and better apply to deep oil and gas exploitation. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a natural plant-based surfactant for high-temperature-resistant synthetic base drilling fluid and a preparation method thereof.

[0006] As an aspect of the present application, a raw material composition is provided, which includes a natural organic matter, an acid-binding agent, N,N dimethylformamide, and a compound containing a long-chain acyl chloride or amine-based monomer.

[0007] In a possible embodiment, the raw material composition includes the following components in parts by weight:

[0008] Natural organic matter: 18-25 parts; acid-binding agent: 6.21-8.28 parts; N,N dimethylformamide: 400-500 parts; compound containing long-chain acyl chloride or amine-based monomer: 18-26.25 parts;

[0009] The natural organic matter contains terpene compounds.

[0010] In a possible embodiment, the natural organic matter is oil tea saponin or dehydroabietic acid.

[0011] In a possible embodiment, the acid-binding agent is potassium carbonate.

[0012] In a possible embodiment, the compound containing long-chain acyl chloride or amine-based monomer is dodecanoyl chloride.

[0013] As another aspect of the present application, it relates to a natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid, wherein the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid comprises a compound having a terpene cyclic skeleton, an oleophilic group and a hydrophilic group, and the terpene cyclic skeleton has a molecular structure with a packing constant P greater than 1.

[0014] In a possible implementation, the oleophilic group is a long-chain alkane double-layer oleophilic group, and the hydrophilic group comprises a carbonacyl group.

[0015] In a possible implementation, the main components of the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid include at least one of a natural organic matter, an acid-binding agent, N,N dimethylformamide and a compound containing a long-chain acyl chloride or amine monomer.

[0016] In a possible implementation, the raw materials of the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid include the following components in the following proportions by weight:

[0017] Natural organic matter: 18-25 parts; acid-binding agent: 6.21-8.28 parts; N,N dimethylformamide: 400-500 parts; compound containing long-chain acyl chloride or amine monomer: 18-26.25 parts;

[0018] The natural organic matter comprises a terpene compound.

[0019] In a possible implementation, the natural organic matter is oil tea saponin or dehydroabietic acid.

[0020] In a possible implementation, the acid-binding agent is potassium carbonate.

[0021] In a possible implementation, the compound containing a long-chain acyl chloride or amine monomer is dodecanoyl chloride.

[0022] As another aspect of the present application, it relates to a method for preparing the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid, and the method comprises the following steps:

[0023] S1: weigh the raw materials according to the proportions, add the natural organic matter and the acid-binding agent to the N,N dimethylformamide and stir, and drop the compound containing the long-chain acyl chloride or amine monomer during the stirring until a mixed solution is obtained through sufficient reaction;

[0024] S2: add the mixed solution to a macroporous adsorption resin for adsorption, wash the macroporous adsorption resin with deionized water, collect the deionized water, then extract with ethyl acetate, and remove the organic solvent through rotary evaporation to obtain a first product;

[0025] S3: wash the macroporous adsorption resin with an ethanol solution, collect the ethanol and remove the organic solvent through rotary evaporation to obtain a second product.

[0026] S4: The first product and the second product are combined, and are ground and crushed to obtain a natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid.

[0027] In possible embodiments, the preparation method satisfies at least one of the following conditions:

[0028] a) In the step S1, the natural organic matter and the acid-binding agent are added to N,N dimethylformamide, and are uniformly stirred at a speed of 200-500 r / min (for example, preferably 300 r / min), and the stirring time is 2-6 h (for example, preferably 4 h) at room temperature;

[0029] b) In the step S2, the macroporous adsorption resin is D101, the resin addition amount is 200-400 g (for example, preferably 250 g), the adsorption time is 0.5-2 h (for example, preferably 1 h), the deionized water addition amount is 300-700 ml (for example, preferably 500 ml), and the ethyl acetate addition amount is 500-900 ml (for example, preferably 750 ml);

[0030] c) In the step S3, the ethanol solution addition amount is 500-900 ml (for example, preferably 700 ml), and the volume percentage is 60-90% (for example, preferably 80%).

[0031] Based on the above technical solutions, the beneficial effects of the present application over the prior art are:

[0032] The natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid disclosed in the present application, by designing the raw material components and their proportions, a rigid surfactant based on a natural terpene polycyclic skeleton is obtained, and by controlling the self-assembly behavior of the surfactant at the oil-water interface, the system is easy to form a water-in-oil emulsion system. Therefore, the technical solution of the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid disclosed in the present application can improve the high-temperature settling of barite and the stability of the system in the synthetic-based drilling fluid system, solve the problems of dispersion and aggregation of inorganic materials, and develop key surfactant materials with high-temperature-resistant barite settling stability.

[0033] In addition, the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid disclosed in the present application connects long-chain alkyl groups through the reaction of the chemical modification sites such as carboxyl groups on the terpene polycyclic skeleton with acyl chloride and amine groups. Not only can it protect the configuration of the surfactant at high temperature, so that it can still maintain good surface activity at a higher temperature, and maintain the use of the drilling fluid system in deep reservoirs; but also the introduction of long-chain alkyl groups can improve the lipophilicity of the surfactant, so that it has better lipophilic effect, and improves its emulsification and dispersion effect in the synthetic-based drilling fluid.

[0034] In addition, the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid described in the present application is particularly suitable for drilling fluid operation environment. When complex fractured formation occurs, sticking problems may occur due to barite settling, and the filtration loss of drilling fluid may also affect the stability of the well wall, which not only affects the drilling efficiency, but also causes serious economic losses and pollution problems. Therefore, the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid described in the present application can be added to improve the performance of synthetic-based drilling fluid, thereby achieving the effects of preventing well leakage pollution, well wall collapse, and safe drilling.

[0035] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application will be realized and achieved by the structure particularly pointed out in the specification, claims, and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0036] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the drawings:

[0037] Figure 1 FT-IR graphs of the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid of Example 1 before and after modification, wherein a is a terpene raw material, and b is a target compound;

[0038] Figure 2 Natural products before and after modification of the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid of Example 1 1 HNMR graphs, wherein a is a terpene raw material, and b is a target compound;

[0039] Figure 3 SEM graphs of barite before and after aging of drilling mud of different examples and a blank sample are shown, wherein a represents barite, b represents a blank sample, c represents Example 1, d represents Experimental Example 2, and the numbers 1 and 2 added after the letters respectively represent before and after high-temperature aging treatment;

[0040] Figure 4 Contact angles of barite before and after aging of drilling mud of different examples and a blank sample are shown, wherein d represents Comparative Example 1, e represents Comparative Example 2, f represents Comparative Example 3, and the numbers 1 and 2 added after the letters respectively represent before and after aging treatment. DETAILED DESCRIPTION

[0041] The present application will be further described below in conjunction with specific embodiments, and the protection scope of the present application is not limited by the following examples.

[0042] The inventor finds in practical work that when drilling in complex fractured formation, drill pipe sticking occurs due to barite settling, and the filtration of drilling fluid also affects the stability of the well wall, which not only affects the drilling efficiency, but also causes serious economic losses and pollution problems. Therefore, the inventor wants to improve the performance of synthetic base drilling fluid by adding a surfactant to prevent well leakage and pollution, well wall collapse, and safe drilling.

[0043] However, the surfactants in the prior art either have insufficient stability and emulsifying capacity due to the high temperature environment of the drilling environment, or have pollution to the environment and high price. Therefore, the inventor has conducted a large number of experimental researches and explored conditions, and designed a rigid surfactant based on a natural terpene polycyclic skeleton to control the self-assembly behavior of the surfactant at the oil-water interface, so that the system can easily form a water-in-oil emulsion system to solve the problems of barite high-temperature settling and system stability in the synthetic base drilling fluid system, and to overcome the problems of inorganic material dispersion and aggregation and settling.

[0044] By modifying the chemical sites such as carboxyl groups on the terpene polycyclic skeleton and reacting with acyl chloride and amine groups, long-chain alkyl groups are connected. This not only protects the configuration of the surfactant at high temperatures, so that it can still maintain good surface activity at higher temperatures, and maintain the use of the drilling fluid system in deep reservoirs; at the same time, the introduction of long-chain alkyl groups can improve the lipophilicity of the surfactant, so that it has better lipophilic effect, and improves its emulsifying and dispersing effect in synthetic base drilling fluid.

[0045] Therefore, the technical scheme of the present application has the following advantages:

[0046] 1. Structural advantage

[0047] The obtained surfactant has a terpene ring skeleton and a long-chain alkane double-layer lipophilic group, and also contains amide and other high-temperature-resistant stable structures.

[0048] The terpene ring skeleton can ensure that the molecular structure has a packing constant P greater than 1, which is beneficial to the formation of a water-in-oil stable emulsion structure; the long-chain alkane lipophilic group can ensure the compatibility with synthetic base drilling fluid.

[0049] In addition, the surfactant also contains hydrophilic groups such as amide connected by carbonyl groups, which provide the amphiphilic properties of the surfactant. This structure is also a high-temperature-resistant stable structure.

[0050] 2. The preparation method of the surfactant is simple and has high yield

[0051] The reaction conditions of the specific preparation steps are simple and not harsh, thus the method is simple, and the high-activity compound of acyl chloride is introduced in the preparation process, ensuring the smooth progress of the reaction, forming stable amide structure, and ensuring high yield.

[0052] 3. Effect advantage in drilling fluid

[0053] As can be seen from the verification data effect, the cover surfactant maintains good flowability and barite surface lipophilicity before and after high-temperature aging treatment, the greater the barite surface contact angle, the better the lipophilicity, and the better the dispersion stability in the synthetic-based drilling fluid.

[0054] Example 1

[0055] A kind of natural plant-based surfactant for high-temperature synthetic-based drilling fluid, the preparation method comprises the following steps:

[0056] (1) 18 g of oil tea saponin and 25 g of potassium carbonate are added to 400 ml of N,N-dimethylformamide (DMF), and stirred uniformly at a speed of 300 r / min. 20 g of dodecanoyl chloride is added dropwise to the mixed solution, and the stirring time is 4 h at room temperature. The mixed solution is obtained after full reaction.

[0057] (2) 250 g of macroporous adsorption resin D101 is added and adsorbed for 1 h. The macroporous adsorption resin is washed with 500 ml of deionized water. The deionized water is collected and extracted with 750 ml of ethyl acetate. The organic solvent is removed by rotary evaporation to obtain the first product.

[0058] (3) The macroporous adsorption resin is further washed with 700 ml of 80% ethanol solution. The ethanol is collected and the organic solvent is removed by rotary evaporation to obtain the second product.

[0059] (4) The first product and the second product are combined and ground to obtain a natural plant-based surfactant for high-temperature synthetic-based drilling fluid.

[0060] Example 2

[0061] A kind of natural plant-based surfactant for high-temperature synthetic-based drilling fluid and its preparation method, comprising the following steps:

[0062] (1) 25 g of dehydroabietic acid and 6.21 g of potassium carbonate are added to 400 ml of N,N-dimethylformamide (DMF), and stirred uniformly at a speed of 300 r / min. 18 g of dodecanoyl chloride is added dropwise to the mixed solution, and the stirring time is 4 h at room temperature. The mixed solution is obtained after full reaction.

[0063] (2) Add 250 g macroporous adsorption resin D101 for adsorption for 1 h, use 500 ml deionized water to flush the macroporous adsorption resin, collect the deionized water and extract by 750 ml ethyl acetate, remove the organic solvent by rotary evaporation to obtain a first product.

[0064] (3) Continue to flush the macroporous adsorption resin with 700 ml of 80% ethanol solution, collect the ethanol and remove the organic solvent by rotary evaporation to obtain a second product.

[0065] (4) Combine the first product and the second product and grind to obtain a natural plant-based surfactant for high-temperature-resistant drilling fluid.

[0066] Example 3

[0067] (1) Add 18 g of oil tea saponin and 8.28 g of potassium carbonate to 400 ml of N,N dimethylformamide (DMF) and uniformly stir at a speed of 300 r / min, add 26.25 g of lauroyl chloride dropwise to the mixed solution, keep the room temperature, and stir for 4 h to obtain a mixed solution.

[0068] (2) Add 250 g macroporous adsorption resin D101 for adsorption for 1 h, use 500 ml deionized water to flush the macroporous adsorption resin, collect the deionized water and extract by 750 ml ethyl acetate, remove the organic solvent by rotary evaporation to obtain a first product.

[0069] (3) Continue to flush the macroporous adsorption resin with 700 ml of 80% ethanol solution, collect the ethanol and remove the organic solvent by rotary evaporation to obtain a second product.

[0070] (4) Combine the first product and the second product and grind to obtain a natural plant-based surfactant for high-temperature-resistant drilling fluid.

[0071] Comparative Example 1

[0072] The preparation method comprises the following steps

[0073] (1) Add 18 g of tannic acid and 4.38 g of potassium carbonate to 400 ml of N,N dimethylformamide (DMF) and uniformly stir at a speed of 300 r / min, add 13.89 g of lauroyl chloride dropwise to the mixed solution, keep the room temperature, and stir for 4 h to obtain a mixed solution.

[0074] (2) Add 250 g macroporous adsorption resin D101 for adsorption for 1 h, use 500 ml deionized water to flush the macroporous adsorption resin, collect the deionized water and extract by 750 ml ethyl acetate, remove the organic solvent by rotary evaporation to obtain a first product.

[0075] (3) continue to rinse the macroporous adsorption resin with 700 ml of 80% ethanol solution, collect the ethanol and remove the organic solvent by rotary evaporation to obtain the partial product.

[0076] (4) combine and grind the products to obtain the surfactant.

[0077] The surfactant of the present comparative example is prepared by using tannic acid as the natural organic matter.

[0078] Comparative Example 2

[0079] The preparation method steps are as follows:

[0080] (1) add 18 g of humic acid and 32.8 g of potassium carbonate into 400 ml of N,N dimethylformamide (DMF) and uniformly stir at a speed of 300 r / min, add 104 g of lauroyl chloride dropwise into the mixed solution, keep the room temperature, and stir for 4 h to obtain a mixed solution.

[0081] (2) add 250 g of macroporous adsorption resin D101 and adsorb for 1 h, rinse the macroporous adsorption resin with 500 ml of deionized water, collect the deionized water and extract by 750 ml of ethyl acetate, and remove the organic solvent by rotary evaporation to obtain the partial product.

[0082] (3) continue to rinse the macroporous adsorption resin with 700 ml of 80% ethanol solution, collect the ethanol and remove the organic solvent by rotary evaporation to obtain the partial product.

[0083] (4) combine and grind the products to obtain the surfactant.

[0084] The surfactant of the present comparative example is prepared by using tannic acid as the natural organic matter.

[0085] Comparative Example 3

[0086] The preparation method steps are as follows:

[0087] (1) add 18 g of humic acid and 32.8 g of potassium carbonate into 400 ml of N,N dimethylformamide (DMF) and uniformly stir at a speed of 300 r / min, add 104 g of lauroyl chloride dropwise into the mixed solution, keep the room temperature, and stir for 4 h to obtain a mixed solution.

[0088] (2) add 250 g of macroporous adsorption resin D101 and adsorb for 1 h, rinse the macroporous adsorption resin with 500 ml of deionized water, collect the deionized water and extract by 750 ml of ethyl acetate, and remove the organic solvent by rotary evaporation to obtain the partial product.

[0089] (3) The macroporous adsorption resin was further rinsed with 700 ml of 80% pure ethanol solution, and the ethanol was collected and the organic solvent was removed by rotary evaporation to obtain a partial product.

[0090] (4) The products are combined and ground to obtain a surfactant.

[0091] The surfactant of this comparative example is prepared using phytic acid as a natural organic matter.

[0092] Test 1 Compatibility test (rheology)

[0093] The compatibility of lost circulation while drilling agents in synthetic drilling fluids was evaluated to determine whether natural plant-based surfactants used in high-temperature resistant drilling fluids can be well dispersed and suspended in synthetic drilling fluids without affecting the rheological properties and stability of the synthetic drilling fluids.

[0094] Preparation of synthetic drilling fluid base slurry: Add 240mL of white oil to a high-stirring cup, and add 24g of main emulsifier HT-MUL, 7.5g of organic soil, 60ml of 20% CaCl2 aqueous solution, 6g of CaO, 12g of filtrate reducer, and 480g of barite with a density of 1.8g / cm3 in sequence under a high-speed stirring speed of 11000r. The stirring time is 20min. After that, stir for 10min each time a treatment agent is added until all raw materials are added and stirred for 40min to obtain the synthetic drilling fluid base liquid.

[0095] Prepared drilling fluid samples were tested at room temperature using a six-speed viscometer before and after aging (180°C, 16 hours). Stable readings of Φ600, Φ300, Φ200, Φ100, Φ6, and Φ3 were recorded at different speeds. The speed was then adjusted to Φ600 for 10 seconds, allowed to stand for 10 seconds, and the maximum value of Φ3 was recorded. This was used as the initial cut-off value (τ10s). The speed was then adjusted to Φ600 for 10 seconds, allowed to stand for 10 minutes, and the maximum value of Φ3 was recorded. This was used as the final cut-off value (τ10min). Apparent viscosity: AV = ηapparent = Φ600 / 2 mPa·s, plastic viscosity: PV = ηplastic = Φ600-Φ300 mPa·s, dynamic shear force: YP = τ0 = (Φ300-PV) / 2 = Φ300-Φ600 / 2 Pa, dynamic-plastic ratio: YP / PV = (Φ300-Φ600 / 2) / (Φ600-Φ300), static shear force: θ = τ10s-τ10min Pa. The rheological parameters of the drilling fluid were tested in accordance with the national standard "GB / T 29170-2012 Laboratory Testing of Drilling Fluids for the Petroleum and Natural Gas Industry." The results are shown in Table 1.

[0096] Table 1 Effect of surfactants prepared in Examples 1-2 and Comparative Examples 1-3 on the rheological properties of drilling fluids

[0097]

[0098]

[0099] As shown in Table 1, after adding the product of the embodiment, the rheological parameters of the drilling fluid before and after aging are basically unchanged compared with the base slurry, indicating that the temperature resistance of the product of the embodiment is excellent, and the rheological property of the drilling fluid is not adversely affected. The performance of each embodiment has a small change in performance parameters compared with the base slurry, and the surface stability is good before and after high-temperature aging.

[0100] The natural terpene natural product raw material is used in Example 1-2, and the natural product can react with dodecanoyl chloride to a certain extent. After modification, the natural product has a certain amphiphilicity, and is well dispersed in the synthetic base drilling fluid and uniformly and stably distributed at the oil-water interface.

[0101] The long-chain alkyl group is introduced at the carboxyl site by acyl chloride to compensate for the defect that the surfactant is easily decomposed at high temperature. The temperature resistance of the product has increased to a certain extent, and the product can be applied to oil drilling engineering in a high-temperature environment.

[0102] Test 2: Oil-wetness characterization

[0103] The method of determining the three-phase contact angle is used. After drying, 10g of the product of the embodiment and the product of the comparative example is weighed, and a thin sheet is prepared by a tablet press under a pressure of 7MPa. The contact angle measuring instrument is used to record the whole process of the deionized water droplet reaching the thin sheet, and the time when the droplet and the thin sheet are in stable contact is found. The contact angle is calculated by analyzing the picture by software, and the results are shown in Table 2.

[0104] Table 2: Contact angle data of the surfactants prepared by Example 1-2 and Comparative Example 1-3

[0105]

[0106] It should be noted that the blank sample refers to a blank group without any surface treatment agent.

[0107] As shown in Table 2, the natural plant surfactant prepared by the embodiment of the present application is an oil-wet surfactant, indicating that it has good oil-wetness. In the comparative example, each modified natural product shows a certain improvement in oil-wetness, and the contact angle decreases by less than the blank comparative sample after high-temperature aging, indicating that each natural product surfactant has a certain high-temperature resistance.

[0108] Figure 1 FT-IR diagram of the compound before and after modification of the natural plant-based surfactant for high-temperature-resistant synthetic base drilling fluid of Example 1, wherein a is a terpene raw material, and b is a target compound.

[0109] As Figure 1 shown, it can be found that some vibration peaks change obviously, especially the new absorption peaks at 2900cm -1 and 1722cm -1 , which indicates that the carbonyl group is introduced into the compound and the target compound is successfully synthesized.

[0110] Figure 2 Natural products before and after modification of natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid of example 1 1 HNMR diagram, wherein a is terpene raw material, and b is target compound.

[0111] As Figure 2 shown, it can be found that due to the introduction of alkyl chain, -CH2 at 1.25ppm position produces strong and sharp vibration peak, which can prove the successful introduction of dodecanoyl chloride into terpene raw material.

[0112] Figure 3 The SEM images of barite before and after aging of drilling mud of different examples and blank sample are shown, wherein a represents barite, b represents blank sample, c represents example 1, d represents experimental example 2, and the numbers 1 and 2 added after the letters respectively represent before and after high-temperature aging treatment.

[0113] Since barite is the main component in drilling mud, as Figure 3 shown, by comparing the SEM images of barite raw material and examples, it can be seen that after the barite is treated with the natural plant-based surfactant for high-temperature-resistant synthetic-based drilling fluid described in the present application, the barite is in granular form and has good dispersibility. Moreover, before and after the surface modification compound is used to treat the barite, the surface of the compound is uniformly dispersed, and the surface structure has no change before and after high-temperature treatment.

[0114] Figure 4 The contact angles of barite before and after aging of drilling mud of different examples and blank sample are shown, wherein d represents comparative example 1, e represents comparative example 2, f represents comparative example 3, and the numbers 1 and 2 added after the letters respectively represent before and after aging treatment.

[0115] It can be seen from table 2 and Figure 4 that the contact angles of barite before and after aging change little, and the contact angles of examples 1 and 2 increase, and the contact angles of comparative examples 1, 2 and 3 decrease.

[0116] The above are only preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Any modification or application made according to the above embodiments is within the protection scope of the technical scheme.

[0117] While the specific embodiments of the application have been described in detail, those skilled in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. The foregoing is intended to cover all modifications and alternatives within the scope of the present application. It is to be understood that the scope of the application fully encompasses other applications such as those that may arise to those who are skilled in the art. It is intended, therefore, that the scope of the application be limited only by the broadest interpretation of the appended claims to which they are fairly incident.

Claims

1. A method for preparing a natural plant-based surfactant for high-temperature resistant synthetic drilling fluid, characterized in that: The preparation method comprises the following steps: S1: Weigh 18-25 parts of natural organic matter, 6.21-8.28 parts of acid-binding agent, 400-500 parts of N,N-dimethylformamide, and 18-26.25 parts of long-chain acyl chloride in proportion; add the natural organic matter and acid-binding agent to N,N-dimethylformamide and stir, and add the long-chain acyl chloride compound dropwise during stirring until the reaction is sufficient to obtain a mixed solution; The natural organic matter is camellia saponin or dehydroabietic acid, the acid-binding agent is potassium carbonate, and the long-chain acyl chloride is dodecanoyl chloride; S2: adding the mixed solution to a macroporous adsorption resin for adsorption, rinsing the macroporous adsorption resin with deionized water, collecting the deionized water, and then extracting with ethyl acetate, and removing the organic solvent by rotary evaporation to obtain a first product; S3: washing the macroporous adsorption resin with an ethanol solution, collecting the ethanol and removing the organic solvent by rotary evaporation to obtain a second product; S4: The first product and the second product are combined, ground and pulverized to obtain a natural plant-based surfactant for high-temperature resistant synthetic drilling fluid.

2. The preparation method according to claim 1, wherein The preparation method satisfies at least one of the following conditions: a) in step S1, the natural organic matter and the acid binding agent are added to N,N-dimethylformamide and stirred at room temperature for 2-6 hours; b) In step S2, the macroporous adsorption resin is D101, the resin addition amount is 200-400 g, the adsorption time is 0.5-2 h, the deionized water addition amount is 300-700 ml, and the ethyl acetate addition amount is 500-900 ml; c) In step S3, the amount of ethanol solution added is 500-900 ml, and the volume percentage is 60-90%.

3. A natural plant-based surfactant for high-temperature resistant synthetic drilling fluid prepared by the preparation method according to any one of claims 1-2.

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