A desorbent, its preparation method and use

Abstract

This invention relates to the field of oil and gas field development technology, and particularly to a desorbent and its preparation method. The invention provides a desorbent comprising the following components in parts by weight: 5-10 parts dimethoxydimethyl silicone oil, 10-20 parts trimethoxymethylsilane, 60-85 parts methanol, and 2-5 parts nonionic surfactant; the dimethoxydimethyl silicone oil has the structure shown in Formula I. The dimethoxydimethyl silicone oil of this invention contains two methoxy functional groups. These two methoxy functional groups hydrolyze to generate silanols, which can react with sand or rock surfaces to form a slippery layer. This slippery layer covering the rock or sand surface has low surface tension, preventing direct contact between crude oil and sand or rock fissures, thus facilitating crude oil penetration and transport.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to a desorbent and its preparation method. Background Technology

[0002] Hydraulic fracturing and its supporting technologies are a new technique for enhancing the production of low-permeability oil and gas reservoirs. Specifically, it involves artificially fracturing the rock layers that impede oil and gas reservoirs underground through hydraulic pressurization, creating interconnected oil seepage and transport channels. The crude oil previously blocked by the rock layers permeates and flows along these new channels (rock fractures), collects, and is then extracted by a pumping unit, achieving increased production and efficiency for individual oil and gas wells. Based on the physicochemical properties and dosage of the fracturing fluid, commonly used fracturing fluids include: oil-based fracturing fluids with white oil as the dispersion medium, water-based fracturing fluids (including emulsion-type fracturing fluids), foam fracturing fluids containing both gas and liquid phases, and acid-based fracturing fluids. The fracturing fluid carries a large amount of sand (proppant) into the newly generated fractures, permanently remaining and filling the fracture gaps, effectively supporting the fractures and keeping them open, preventing the rock fractures from closing spontaneously due to a drop in internal reservoir pressure later on. Crude oil gradually infiltrates and accumulates through the gaps between sand filling the rock fissures, achieving the goal of increasing production and efficiency in a single well. The production-enhancing effect of fracturing technology is particularly significant for oil reservoirs with narrow flow channels and low permeability.

[0003] Hydraulic fracturing involves fracturing the rock and supporting a large amount of sand carried by the fracturing fluid within the fractures, creating new channels for oil seepage and transport. When viscous crude oil comes into contact with the sand and the newly formed fractures, the crude oil coats the surface of the sand and rock fissures, forming a boundary layer of a certain thickness. This layer generates a large gradient viscosity force that hinders oil transport and permeation, reducing the oil production per unit time. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a desorbent and its preparation method. Upon entering an oil well, the desorbent of this invention rapidly adsorbs onto the surface of sand and rock fissures, and undergoes a condensation reaction with the silanol groups on the sand and rock fissure surfaces to form a slippery, low-surface-tension molecular layer. This layer prevents crude oil from physically adsorbing onto the surface of the oil well channel, thus preventing the formation of a crude oil boundary layer, reducing crude oil penetration and transport resistance, and achieving a slippery oil well channel.

[0005] To achieve the above objectives, the present invention provides a desorbent comprising the following components in parts by weight:

[0006]

[0007] The dimethoxydimethyl silicone oil has the structure shown in Formula I:

[0008] In Equation I, the range of n is 9 ≤ n ≤ 46.

[0009] Preferably, the nonionic surfactant is one or more of Tween 20, Tween 40, Tween 65, Tween 80, Tween 81 and Tween 85.

[0010] Preferably, the method for preparing the dimethoxydimethyl silicone oil includes the following steps:

[0011] Under a protective atmosphere, monosilanol dimethyl silicone oil, trimethoxymethylsilane and alkaline catalyst are mixed to obtain dimethoxydimethyl silicone oil;

[0012] The monosilyl dimethyl silicone oil has the structure shown in Formula I-1:

[0013] The range of n is 9 ≤ n ≤ 46.

[0014] Preferably, the molar ratio of the monosilanol dimethyl silicone oil and the trimethoxymethylsilane is 1:1.

[0015] Preferably, the alkaline catalyst comprises one or more of sodium methoxide, potassium methoxide, sodium hydroxide, and potassium hydroxide.

[0016] Preferably, the mass ratio of the monosilanol dimethyl silicone oil and trimethoxymethylsilane to the alkaline catalyst is 100:0.02-0.05.

[0017] The present invention also provides a method for preparing the above-described desorbent, comprising the following steps:

[0018] A desorbent is obtained by mixing dimethoxydimethyl silicone oil, trimethoxymethylsilane, methanol, and a nonionic surfactant under a protective atmosphere.

[0019] Preferably, the mixture is:

[0020] Dimethoxydimethyl silicone oil and trimethoxymethylsilane were first mixed to obtain a mixture;

[0021] Methanol and a nonionic surfactant were added dropwise to the mixture for a second mixing.

[0022] Preferably, the dripping is carried out under stirring conditions, and the stirring speed is 2000-3000 rpm.

[0023] The present invention also provides the application of the desorbent described above or the desorbent prepared by the preparation method described above in oil transportation.

[0024] This invention provides a desorbent comprising the following components in parts by weight: 5-10 parts dimethoxydimethyl silicone oil, 10-20 parts trimethoxymethylsilane, 60-85 parts methanol, and 2-5 parts nonionic surfactant; wherein the dimethoxydimethyl silicone oil has the structure shown in Formula I. The dimethoxydimethyl silicone oil of this invention contains two methoxy functional groups. These two methoxy functional groups hydrolyze to generate silanols, which can react with sand or rock surfaces to form a slippery layer. This slippery layer covering the rock or sand surface has low surface tension, preventing direct contact between crude oil and sand or rock fissures, thus facilitating crude oil penetration and transport. In this invention, the trimethoxymethylsilane preferentially reacts with trace amounts of water molecules in the environment during the storage and transportation of the desorbent, preventing the methoxy groups in the dimethoxydimethyl silicone oil from being hydrolyzed and becoming ineffective; methanol is used to prepare the dimethoxydimethyl silicone oil into a dispersion, reducing the viscosity of the system and facilitating pumping and accurate metering; the nonionic surfactant acts as a compatibilizer, stably dispersing the dimethoxydimethyl silicone oil in methanol. Attached Figure Description

[0025] Figure 1 Infrared spectra of dimethoxydimethyl silicone oil used in Examples 1-3;

[0026] Figure 2 The static contact angle between the glass slide and the water treated with the desorbent in Examples 1-3;

[0027] Figure 3 The mass of crude oil solution passing through the ceramic sand layer and the ceramic sand layer treated with a desorbent within the same time period. Detailed Implementation

[0028] This invention provides a desorbent comprising the following components in parts by weight:

[0029]

[0030] The dimethoxydimethyl silicone oil has the structure shown in Formula I:

[0031] In Equation I, the range of n is 9 ≤ n ≤ 46.

[0032] In this invention, the desorbent comprises, by weight, 5-10 parts of dimethoxydimethyl silicone oil, preferably 7-8 parts. In this invention, the dimethoxydimethyl silicone oil has the structure shown in Formula I:

[0033] In Equation I, the range of n is 9 ≤ n ≤ 46.

[0034] In this invention, the number-average molecular weight of the dimethoxydimethyl silicone oil is preferably 0.8 × 10⁻⁶. 3 g / mol ~ 3.5 × 10 3 g / mol.

[0035] In this invention, the desorbent comprises 10-20 parts by mass of trimethoxymethylsilane, preferably 15 parts.

[0036] In this invention, the desorbent contains 60-85 parts of methanol, preferably 70-80 parts, by mass.

[0037] In this invention, the desorbent comprises 2-5 parts by mass of a nonionic surfactant, preferably 3-4 parts. In this invention, the nonionic surfactant is preferably one or more of Tween 20, Tween 40, Tween 65, Tween 80, Tween 81, and Tween 85, more preferably Tween 65 or Tween 80.

[0038] In this invention, the desorbent further includes an alkaline catalyst, which is preferably one or more of sodium methoxide, potassium methoxide, sodium hydroxide, and potassium hydroxide, and more preferably sodium methoxide.

[0039] In this invention, the alkaline catalyst is transferred from the modified methoxydimethyl silicone oil to methanol. This not only stabilizes the structure and properties of the methoxydimethyl silicone oil, but also accelerates the hydrolysis of the methoxy groups in the methoxydimethyl silicone oil and trimethoxymethylsilane during the desorbent application stage, allowing them to rapidly undergo a condensation reaction with the rock and sand surface.

[0040] In this invention, the preparation method of the dimethoxydimethyl silicone oil includes the following steps:

[0041] Under a protective atmosphere, monosilanol dimethyl silicone oil, trimethoxymethylsilane and alkaline catalyst are mixed to obtain dimethoxydimethyl silicone oil;

[0042] The monosilyl dimethyl silicone oil has the structure shown in Formula I-1:

[0043] The range of n is 9 ≤ n ≤ 46.

[0044] This invention involves mixing monosilyl dimethyl silicone oil, trimethoxymethylsilane, and an alkaline catalyst to undergo a condensation reaction, thereby obtaining dimethoxydimethyl silicone oil.

[0045] In this invention, the number-average molecular weight of the monosilanol-based dimethyl silicone oil is preferably 0.8 × 10⁻⁶. 3 g / mol ~ 3.5 × 103 g / mol, more preferably 0.8 × 10 g / mol. 3 g / mol, 1.5×10 3 g / mol, 2.0×10 3 g / mol, 2.5×10 3 g / mol, 3.5×10 3 g / mol. In this invention, the protective atmosphere is preferably high-purity nitrogen, and the purity of the high-purity nitrogen is preferably ≥99.99%.

[0046] In this invention, the molar ratio of the monosilanol dimethyl silicone oil and trimethoxymethylsilane is preferably 1:1. In this invention, the mass ratio of the monosilanol dimethyl silicone oil and trimethoxymethylsilane to the alkaline catalyst is preferably 100:0.02–0.05, more preferably 100:0.03–0.04.

[0047] In this invention, the mixing is preferably carried out by first heating the monosilyl dimethyl silicone oil to 50-70°C, and then mixing it with trimethoxymethylsilane and an alkaline catalyst.

[0048] In this invention, the temperature of the condensation reaction is preferably 50-70°C, more preferably 60°C, and the time is preferably 30 min.

[0049] In this invention, after the condensation reaction, the process preferably further includes sequentially removing air bubbles from the condensation reaction system, continuing the condensation reaction, cooling, and filtering. In this invention, the method of removing air bubbles is preferably vacuuming, and the vacuuming is preferably performed to a vacuum degree ≤ -0.095 kPa. In this invention, the continued condensation reaction is preferably performed for 30 minutes to ensure a more complete reaction. In this invention, the cooling is preferably performed to room temperature. In this invention, the purpose of the filtration is to remove the alkaline catalyst from the system. In this invention, the filtration is not specifically limited, and any filtration operation well known in the art can be used.

[0050] The present invention also provides a method for preparing the above-described desorbent, comprising the following steps:

[0051] A desorbent is obtained by mixing dimethoxydimethyl silicone oil, trimethoxymethylsilane, methanol, and a nonionic surfactant under a protective atmosphere.

[0052] In this invention, the mixing is preferably:

[0053] Dimethoxydimethyl silicone oil and trimethoxymethylsilane were first mixed to obtain a mixture;

[0054] Methanol and a nonionic surfactant were added dropwise to the mixture for a second mixing.

[0055] In this invention, the first mixing method is preferably stirring, and the stirring speed is preferably 2000-3000 rpm, more preferably 2500 rpm.

[0056] In this invention, the dripping is preferably carried out under stirring conditions, and the stirring speed is preferably 2000-3000 rpm, more preferably 2500 rpm.

[0057] In this invention, after the droplet is added, it is preferable to continue stirring for 30 minutes to ensure that the materials are mixed more thoroughly.

[0058] In this invention, the mixing process preferably further includes filtering the resulting mixture. The purpose of filtering is to remove mechanical impurities introduced during the mixing process.

[0059] The present invention also provides the application of the desorbent described above or the desorbent prepared by the preparation method described above in oil transportation.

[0060] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0061] Example 1

[0062] The preparation method of dimethoxydimethyl silicone oil includes the following steps:

[0063] (1) At room temperature, add 0.1 mol (80.00 g) of monosilanol dimethyl silicone oil (number average molecular weight M) to the reaction vessel. n =0.8×10 3 (g / mol). Under stirring conditions, the air in the system was completely replaced with high-purity nitrogen.

[0064] (2) Under a nitrogen atmosphere, the material temperature is slowly raised to 70°C, and 13.62 g (0.1 mol) of trimethoxymethylsilane and 0.1872 g (0.2% of the total mass of monosilyl dimethyl silicone oil and trimethoxymethylsilane) of sodium methoxide are added in sequence.

[0065] (3) React for 30 min under a nitrogen atmosphere and at 70 °C. Then, while stirring, evacuate the system (vacuum degree ≤ -0.095 kPa) until no more bubbles are generated or expelled. Continue the reaction at 70 °C for another 30 min, then cool to room temperature, filter, and obtain dimethoxydimethyl silicone oil.

[0066] The preparation method of the desorbent includes the following steps:

[0067] (1) Add 5 parts of dimethoxydimethyl silicone oil to the reaction vessel. Then, under a nitrogen atmosphere, slowly add 10 parts of trimethoxymethylsilane and stir for 30 minutes to obtain a uniform and transparent solution.

[0068] (2) Under room temperature and stirring conditions of 2000 rpm, 60 parts of methanol and 2 parts of Tween 20 were mixed evenly, and then a mixture of dimethoxydimethyl silicone oil and trimethoxymethylsilane was gradually added dropwise. When the mixture of silicone oil and silane was completely added, the mixture was stirred at high speed for 30 min. The mixture was then filtered to obtain the desorbent.

[0069] Example 2

[0070] The preparation method of dimethoxydimethyl silicone oil includes the following steps:

[0071] (1) At room temperature, add 0.1 mol of monosilanol dimethyl silicone oil (number average molecular weight M) to the reaction vessel. n =3.5×10 3 (g / mol). Under stirring conditions, the air in the system was completely replaced with high-purity nitrogen.

[0072] (2) Under a nitrogen atmosphere, the material temperature is slowly raised to 70°C, and 13.62 g (0.1 mol) of trimethoxymethylsilane and 0.1872 g (0.2% of the total mass of monosilyl dimethyl silicone oil and trimethoxymethylsilane) of sodium methoxide are added in sequence.

[0073] (3) React for 30 min under a nitrogen atmosphere and at 70 °C. Then, while stirring, evacuate the system (vacuum degree ≤ -0.095 kPa) until no more bubbles are generated or expelled. Continue the reaction at 70 °C for another 30 min, then cool to room temperature, filter, and obtain dimethoxydimethyl silicone oil.

[0074] The preparation method of the desorbent includes the following steps:

[0075] (1) Add 10 parts of dimethoxydimethyl silicone oil to the reaction vessel. Then, under a nitrogen atmosphere, slowly add 20 parts of trimethoxymethylsilane and stir for 30 minutes to obtain a uniform and transparent solution.

[0076] (2) Under room temperature and stirring conditions of 3000 rpm, 85 parts of methanol and 5 parts of Tween 80 were mixed evenly, and then a mixture of dimethoxydimethyl silicone oil and trimethoxymethylsilane was gradually added dropwise. After the mixture of silicone oil and silane was completely added, stirring was continued for 30 min, and then the mixture was filtered to obtain the desorbent.

[0077] Example 3

[0078] The preparation method of dimethoxydimethyl silicone oil includes the following steps:

[0079] (1) At room temperature, 0.065 mol of number-average molecular weight M was added to the reaction vessel. n =1.5×10 3 g / mol monosilanol dimethyl silicone oil and 0.035 mol number-average molecular weight M n =2.5×10 3 g / mol monosilanol dimethyl silicone oil. Under stirring conditions, the air in the system was completely replaced with high-purity nitrogen.

[0080] (2) Under a nitrogen atmosphere, the material temperature is slowly raised to 70°C, and 13.62 g (0.1 mol) of trimethoxymethylsilane and 0.1872 g (0.2% of the total mass of monosilyl dimethyl silicone oil and trimethoxymethylsilane) of sodium methoxide are added in sequence.

[0081] (3) React for 30 min under a nitrogen atmosphere and at 70 °C. Then, while stirring, evacuate the system (vacuum degree ≤ -0.095 kPa) until no more bubbles are generated or expelled. Continue the reaction at 70 °C for another 30 min, then cool to room temperature, filter, and obtain dimethoxydimethyl silicone oil.

[0082] The preparation method of the desorbent includes the following steps:

[0083] A desorbent is prepared by the following steps:

[0084] (1) Add 8 parts of dimethoxydimethyl silicone oil (62.5 wt% monosilyl dimethyl silicone oil M) to the reaction vessel. n =1.5×10 3 g / mol; 37.5 wt% monosilanol dimethyl silicone oil M n =2.5×10 3 Then, under a nitrogen atmosphere, 15 parts of trimethoxymethylsilane were slowly added and stirred for 30 minutes to obtain a homogeneous and transparent solution.

[0085] (2) Under room temperature and high-speed stirring conditions (2500 rpm), 75 parts of methanol and 3 parts of nonionic surfactant (Tween 40 and Tween 85 mixed at a mass ratio of 3:1) were mixed evenly, and then a mixture of dimethoxydimethyl silicone oil and trimethoxymethylsilane was gradually added dropwise. After the silicone oil and silane mixture was completely added, high-speed stirring was continued for 30 min. The mixture was filtered to obtain the desorbent.

[0086] Performance testing:

[0087] (1) Structural characterization:

[0088] The structures of the dimethoxydimethyl silicone oils used in Examples 1-3 were characterized using Fourier transform infrared spectroscopy, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that at a wavenumber of 1026 cm⁻¹ -1 and 1091cm -1 The absorption peak at 1262 cm⁻¹ is attributed to the Si-O-Si absorption peak in monosilanol dimethyl silicone oil. -1 The absorption peak at [value missing] corresponds to the Si-CH3 absorption peak in monosilanol dimethyl silicone oil, indicating that the monosilanol dimethyl silicone oil structure has entered the dimethoxy silicone oil structure, proving the successful synthesis of dimethoxy dimethyl silicone oil. Additionally, it should be noted that the infrared spectrum of Si-OCH3 will be at 1000 cm⁻¹. -1 An absorption peak appears at this location, but it overlaps with the characteristic absorption peak of Si-O-Si. In addition, the content of Si-OCH3 is relatively low, so the absorption peak of Si-OCH3 is not obvious.

[0089] (2) Contact angle test:

[0090] First, cut clean glass slides into square pieces approximately 12.5mm × 12.5mm in size using a glass cutter. Then, place them in a beaker containing anhydrous ethanol and sonicate for 30 minutes. Next, carefully wash them three times with distilled water. Dry them in an oven at 80°C for later use. At room temperature, mix the desorbents obtained in Examples 1-3 with equal masses of deionized water. Under stirring, immerse clean glass slides in the mixture for 30 seconds, then remove them. First, absorb the solution from the four corners of the glass slides with absorbent paper, then dry them in an 80°C forced-air drying oven. Use a contact angle meter to measure the static contact angle of the glass slide surface after treatment with different slip agents using distilled water. The results are as follows: Figure 2 As shown.

[0091] Depend on Figure 2 It can be seen that the water contact angle of the untreated glass sheet is 33.7°, while the water contact angles of the glass sheets treated in Examples 1-3 are 87.8°, 97.3°, and 90.5°, respectively. After treatment with the desorbent, the water contact angle of the glass sheet increased by about 60°. This indicates that after treatment with the products in Examples 1-3, the surface tension of the glass decreased, and its surface properties changed from hydrophilic to hydrophobic, thereby preventing crude oil from forming an adsorption layer on the surface of rocks or sand, and reducing the resistance to crude oil penetration and transportation.

[0092] (3) Crude oil liquidity properties

[0093] Ceramsite particles with a diameter of approximately 2 mm were placed in a beaker containing anhydrous ethanol and sonicated for 30 minutes, then carefully washed three times with distilled water. They were then dried in an oven at 80°C until constant weight. At room temperature, the desorbents obtained in Examples 1-3 were mixed with equal masses of deionized water. Under stirring, the clean ceramsite particles were immersed in the mixture for 30 seconds, then removed. The solution adhering to the surface of the ceramsite particles was drained off, and then dried in an 80°C forced-air drying oven.

[0094] The treated ceramic sand was packed into glass tubes with a core at one end and a diameter of 30 mm. The height of the ceramic sand layer was controlled at 100 ± 2 mm. Viscous crude oil and petroleum ether (60-90) were mixed thoroughly at a mass ratio of 4:1. 150 g of the crude oil-to-petroleum ether solution was poured into the glass tube containing the ceramic sand, and the mass of the crude oil solution flowing out within 30 seconds was recorded. The mass of the crude oil solution flowing through the ceramic sand-filled glass tube was used to evaluate the effect of the desorbent on the permeability and transport performance of the crude oil. The results are as follows: Figure 3 As shown.

[0095] Depend on Figure 3 It can be seen that the mass of crude oil solution flowing through the untreated ceramic sand layer and the ceramic sand layers treated in Examples 1-3 within 30 seconds were 0.45g, 1.52g, 1.88g, and 1.67g, respectively. This indicates that the ceramic sand treated with the desorbent prepared in Examples 1-3 prevents the adsorption of crude oil on the surface of the ceramic sand, which is beneficial to the penetration and transportation of crude oil, thereby increasing the daily production of the oil well.

[0096] The above experimental data show that the desorbent of this invention, after entering the oil well, will quickly adsorb onto the surface of sand and rock fissures, and undergo a condensation reaction with the silanol groups on the surface of the sand and rock fissures to form a smooth, low surface tension molecular layer. It is precisely the presence of this smooth molecular layer that prevents crude oil from physically adsorbing on the surface of the oil well channel to form a crude oil boundary layer, greatly reducing the resistance to crude oil penetration and transport, thus achieving the effect of a smooth oil well channel.

[0097] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a desorbent, characterized in that, Includes the following steps: S1. At room temperature, 0.1 mol of monosilanol dimethyl silicone oil with a number-average molecular weight M is added to the reaction vessel. n =3.5×10 3 g / mol, under stirring conditions, the air in the system is completely replaced with high-purity nitrogen; S2. Under a nitrogen atmosphere, slowly raise the material temperature to 70 °C, and add 13.62 g of 0.1 mol of trimethoxymethylsilane, sodium methoxide at a mass of 0.2% of the total mass of monosilyl dimethyl silicone oil and trimethoxymethylsilane in sequence. S3. Under a nitrogen atmosphere and at 70 °C, the reaction was carried out for 30 min. Then, while stirring, a vacuum was drawn with a vacuum degree ≤ -0.095 kPa until no bubbles were generated or discharged in the system. The reaction was continued at 70 °C for another 30 min. After cooling to room temperature, the mixture was filtered to obtain dimethoxydimethyl silicone oil. S4. In the reaction vessel, add 10 parts of dimethoxydimethyl silicone oil, and then, under a nitrogen atmosphere, slowly add 20 parts of trimethoxymethylsilane and stir for 30 min to obtain a uniform and transparent solution. S5. Under room temperature and stirring conditions of 3000 rpm, 85 parts of methanol and 5 parts of Tween 80 were mixed evenly, and then a mixture of dimethoxydimethyl silicone oil and trimethoxymethylsilane was gradually added dropwise. When the mixture of silicone oil and silane was completely added, stirring was continued for 30 min and then filtered to obtain the desorbent.

2. The application of the desorbent according to claim 1 in oil transportation.

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