A low-temperature polyether demulsifier for oil and gas gathering and transportation and a preparation method thereof

Abstract

This invention discloses a low-temperature polyether demulsifier for oil and gas gathering and transportation and its preparation method, relating to the field of petrochemical technology. The key technical points include: using cashew nut shell powder, pentaethylene hexamine, and bisphenol F in a specific molar ratio as an initiator, and preparing a composite initiator via formaldehyde condensation; incorporating propylene oxide and ethylene oxide through staged block copolymerization to form a polyether backbone; introducing fluorinated epoxy monomers for end-fluorination modification; and finally, performing chain extension and crosslinking with adipic acid and epichlorohydrin to obtain a demulsifier with a molecular weight of 8000~12000 Da, a fluorine content of 5.5~6.5 wt%, and a PDI ≤ 1.3. The effect is that through the synergistic effect of the composite initiator, the superhydrophobic penetration of the fluorinated block, and precise molecular weight control, efficient demulsification at low temperatures is achieved, improving demulsification efficiency and reducing dosage, solving the problems of low-temperature failure and easy emulsification of traditional demulsifiers, and adapting to the low-temperature operating conditions of oil and gas gathering and transportation.

Description

A low-temperature polyether demulsifier for oil and gas gathering and transportation and its preparation method Technical Field

[0001] This invention relates to the field of petrochemical technology, and more specifically, to a low-temperature polyether demulsifier for oil and gas gathering and transportation and its preparation method. Background Technology

[0002] As oilfield development enters its mid-to-late stages, crude oil emulsion systems exhibit a triple trend of increasing complexity: enhanced emulsion stability, with high asphaltene / colloid content and polymer flooding agent residues forming a rigid interfacial film; normalization of low temperatures, with deep reservoir development and cold-region gathering and transportation leading to processing temperatures dropping to 25-40℃, significantly increasing the diffusion barrier of traditional demulsifiers; and increased compositional complexity, with mixed transportation of heavy and light oils and an increase in the proportion of polymer- or sulfur-containing crude oils, requiring demulsifiers to have broad-spectrum adaptability.

[0003] Existing technologies such as CN105968369A improve performance by introducing siloxane structures, but their low-temperature adaptability is still limited; CN116375997A combines polycarbonate blocks to optimize hydrophilicity, but the process is highly complex.

[0004] Therefore, there is an urgent need to develop a low-temperature polyether demulsifier for oil and gas gathering and transportation that combines low-temperature high-efficiency demulsification, broad applicability, and simplified preparation process. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a low-temperature polyether demulsifier for oil and gas gathering and transportation, and its preparation method.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation, the specific steps of which are as follows:

[0008] S1: Cashew nut phenol, pentaethylene hexamine and bisphenol F are mixed and added to a reaction vessel. A 30-40 wt% formaldehyde aqueous solution with a cashew nut phenol content of 0.4-0.6% by weight is added dropwise. The reaction is carried out at 45-50 °C for 1-2 h. Xylene with a formaldehyde aqueous solution of 1.5-2 times the mass is added. The mixture is heated to 140-150 °C and refluxed for 2-3 h to remove water, thus obtaining a composite initiator.

[0009] S2: Mix the composite initiator with potassium hydroxide and add it to the reactor. High-purity nitrogen gas and propylene oxide are introduced. The reaction is carried out at a temperature of 120~125 ℃ and a pressure of 0.25~0.35 MPa for 2.5~3 h.

[0010] S3: Ethylene oxide is introduced into the reactor and reacted for 1.5 to 2.5 h at a temperature of 110~120 ℃ and a pressure of 0.2~0.3 MPa;

[0011] S4: Add a fluorinated epoxy monomer to the reactor and react at a temperature of 105~115 ℃ and a pressure of 0.15~0.25 MPa for 3~4 h to obtain product A;

[0012] S5: Mix product A with adipic acid, add epichlorohydrin, and react at a temperature of 120~130 ℃ and a vacuum of 0.04 MPa for 2~3 h. Dissolve in ethyl acetate, wash with water to remove salt, and distill under reduced pressure to obtain the low-temperature polyether demulsifier for oil and gas gathering and transportation.

[0013] The above-mentioned scheme of the present invention overcomes the limitations of the single function of traditional demulsifiers through multi-step synergistic design such as initiator condensation, block copolymerization and chain extension crosslinking. For example, fluorinated blocks can effectively reduce surface energy and enhance the oil-water interface penetration ability at low temperatures of -10℃ to 10℃; the composite initiator and EO / PO blocks work synergistically to balance hydrophilicity and hydrophobicity and interface rigidity; the staged reaction precisely controls the molecular structure and avoids side reactions.

[0014] Preferably, in S1, cashew phenol, pentaethylene hexamine and bisphenol F are mixed in a molar ratio of 1:(0.3~0.5):(0.2~0.4).

[0015] In the above-described scheme of this invention, excessive cashew phenol leads to insufficient interfacial rigidity, while insufficient cashew phenol results in excessive hydrophobicity, hindering diffusion. A suitable proportion of pentaethylenehexamine ensures moderate dendritic structure density, avoiding steric hindrance. Bisphenol F provides adequate aromatic ring stacking, preventing excessive softening of the interfacial film. Compared to traditional two-component initiators, the synergistic effect of these three functions significantly improves demulsification efficiency.

[0016] Preferably, the amount of potassium hydroxide added in S2 is 3-5% of the mass of the composite initiator.

[0017] In the above-mentioned scheme of the present invention, the addition of 3~5% KOH is the optimal amount for epoxy ring-opening polymerization. Excessive amount will lead to side reactions such as ether bond breaking. At the same time, it can ensure the uniform insertion of PO / EO monomers and avoid block unevenness caused by localized overly rapid polymerization. In addition, it can reduce the residue of unreacted monomers and reduce the ash content of the final product.

[0018] Preferably, the molar ratio of the composite initiator to propylene oxide in S2 is 1:(50~60).

[0019] In the above-described scheme of the present invention, the PO can form a sufficiently long polypropylene ether chain under the specified ratio, thereby enhancing the affinity of the oil phase; the moderately long hydrophobic chain avoids excessive molecular coiling and maintains molecular diffusion activity at -10℃; the long-chain PO segment provides driving force and shortens the oil-water separation time.

[0020] Preferably, the molar ratio of the composite initiator to ethylene oxide in S3 is 1:(15~20).

[0021] In the above-described scheme of the present invention, the EO unit forms a hydrophilic head of polyvinyl ether under the specified ratio, ensuring the solubility in the aqueous phase; the EO segment forms hydrogen bonds with water molecules to prevent water droplets from re-aggregating after demulsification; the EO / PO ratio keeps the HLB value at 8~10, which is suitable for the demulsification requirements of crude oil emulsions.

[0022] Preferably, the fluorinated epoxy monomers in S4 include, but are not limited to, perfluoroalkoxycyclohexane and hexafluoropropylene trimer derivatives.

[0023] The above-described solution of the present invention significantly reduces the surface energy of perfluoroalkoxycyclohexane by reducing its fluorine content, which is far lower than that of traditional hydrocarbon-based demulsifiers; the fluorinated segments accumulate at the oil-water interface, forming a fluorinated layer that disrupts the stabilizing effect of asphaltenes / colloids in crude oil; in addition, the fluorinated groups reduce the dissolution loss of the demulsifier in the oil phase and improve the reusability.

[0024] Preferably, the molar ratio of the composite initiator and the fluorinated epoxy monomer in S4 is 1:(3~5).

[0025] In the above-described scheme of this invention, the composite initiator and the fluorinated epoxy monomer are added at a molar ratio of 3-5 to ensure the final fluorine content, which guarantees the superhydrophobic effect while avoiding the cost increase caused by excessive fluorine. The fluorinated monomer is added later to avoid competition for reaction sites with EO / PO, ensuring that the fluorinated segments are uniformly distributed at the molecular ends.

[0026] Preferably, in S5, product A is mixed with adipic acid in a molar ratio of 1:(2~3).

[0027] In the above-mentioned scheme of the present invention, adipic acid reacts with the hydroxyl group of product A to form an ester bond, thereby increasing the molecular weight; moderate chain extension avoids excessive molecular entanglement and maintains the molecular flexibility of the demulsifier; the temperature resistance of the ester bond structure is better than that of the ether bond, which is suitable for oil and gas gathering and transportation conditions.

[0028] Preferably, the molar ratio of adipic acid to epichlorohydrin in S5 is 1:(2~3).

[0029] In the above-mentioned scheme of the present invention, epichlorohydrin is used as a crosslinking agent to react with the carboxyl groups of adipic acid to form a crosslinked network; the degree of crosslinking is controlled by the molar ratio to ensure that PDI ≤ 1.3, thus avoiding gelation; moderate crosslinking can enhance the retention ability of the demulsifier at the oil-water interface and reduce loss.

[0030] Preferably, the low-temperature polyether demulsifier obtained in S5 has a molecular weight of 8000~12000 Da, a molecular weight distribution index (PDI) ≤ 1.3, and a fluorine content of 5.5~6.5 wt%.

[0031] In the above-mentioned scheme of the present invention, 8000~12000 Da is the optimal range for demulsification of crude oil emulsion (particle size 1~100 μm). If the molecules are too small, the adsorption will be insufficient, and if they are too large, the diffusion will be slow. Narrow distribution PDI≤1.3 can ensure uniform molecular properties and avoid the phenomenon of poor diffusion caused by some molecules being too short or too long.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] By synergistically designing a cashew nut phenol-polyethylene polyamine-bisphenol F composite initiator, employing superhydrophobic penetration of fluorinated blocks, and precisely controlling molecular weight, high-efficiency demulsification at low temperatures is achieved. The composite initiator balances hydrophobic anchoring, rapid diffusion, and interfacial rigidity, overcoming the limitations of single initiators. The fluorinated blocks reduce surface energy, enhancing the ability to disrupt the oil-water interface at -10℃ to 10℃. Narrow molecular weight distribution and fluorine content ensure a balance between adsorption efficiency and cost, thereby improving demulsification efficiency and reducing dosage. This solves the problems of low-temperature failure and easy emulsification of traditional agents, making it suitable for the low-temperature operating conditions of oil and gas gathering and transportation. Detailed Implementation

[0034] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0035] Example 1

[0036] A method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation, the specific steps of which are as follows:

[0037] S1: Cashew nut phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.4:0.3 and added to a reaction vessel. A 35 wt% formaldehyde aqueous solution with a cashew nut phenol content of 0.5% was added dropwise. The reaction was carried out at 47 °C for 1.5 h. Xylene with a mass of 1.7 times that of the formaldehyde aqueous solution was added. The mixture was heated to 145 °C and refluxed for dehydration for 2.5 h to obtain a composite initiator.

[0038] S2: The composite initiator is mixed with potassium hydroxide and added to the reactor. The amount of potassium hydroxide added is 4% of the mass of the composite initiator. High-purity nitrogen gas is introduced, and propylene oxide is introduced. The molar ratio of the composite initiator to propylene oxide is 1:55. The reaction is carried out at a temperature of 122 ℃ and a pressure of 0.3 MPa for 2.8 h.

[0039] S3: Ethylene oxide is introduced into the reactor. The molar ratio of the composite initiator to ethylene oxide is 1:18. The reaction is carried out at a temperature of 115 °C and a pressure of 0.25 MPa for 2 h.

[0040] S4: Add perfluoroalkoxycyclohexane to the reactor. The molar ratio of the composite initiator to perfluoroalkoxycyclohexane is 1:4. React at 110 °C and 0.2 MPa for 3.5 h to obtain product A.

[0041] S5: Mix product A with adipic acid at a molar ratio of 1:2.5, add epichlorohydrin (the molar ratio of adipic acid to epichlorohydrin is 1:2.5), and react at 125 °C and 0.04 MPa for 2.5 h. Dissolve in ethyl acetate, wash with water to remove salt, and distill under reduced pressure to obtain the low-temperature polyether demulsifier for oil and gas gathering and transportation.

[0042] Example 2

[0043] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.3:0.2, and the remaining steps were the same as in Example 1.

[0044] Example 3

[0045] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.3:0.3, and the remaining steps were the same as in Example 1.

[0046] Example 4

[0047] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.3:0.4, and the remaining steps were the same as in Example 1.

[0048] Example 5

[0049] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.4:0.2, and the remaining steps were the same as in Example 1.

[0050] Example 6

[0051] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.4:0.4, and the remaining steps were the same as in Example 1.

[0052] Example 7

[0053] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.5:0.2, and the remaining steps were the same as in Example 1.

[0054] Example 8

[0055] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.5:0.3, and the remaining steps were the same as in Example 1.

[0056] Example 9

[0057] Cashew phenol, pentaethylene hexamine and bisphenol F were mixed in a molar ratio of 1:0.5:0.4, and the remaining steps were the same as in Example 1.

[0058] Example 10

[0059] The amount of potassium hydroxide added was 3% of the mass of the composite initiator, and the remaining steps were the same as in Example 1.

[0060] Example 11

[0061] The amount of potassium hydroxide added was 5% of the mass of the composite initiator, and the remaining steps were the same as in Example 1.

[0062] Example 12

[0063] The molar ratio of the composite initiator to propylene oxide was 1:50, and the remaining steps were the same as in Example 1.

[0064] Example 13

[0065] The molar ratio of the composite initiator to propylene oxide was 1:60, and the remaining steps were the same as in Example 1.

[0066] Example 14

[0067] The molar ratio of the composite initiator to ethylene oxide was 1:15, and the remaining steps were the same as in Example 1.

[0068] Example 15

[0069] The molar ratio of the composite initiator to ethylene oxide was 1:20, and the remaining steps were the same as in Example 1.

[0070] Example 16

[0071] The molar ratio of the composite initiator to perfluoroalkoxycyclohexane was 1:3, and the remaining steps were the same as in Example 1.

[0072] Example 17

[0073] The molar ratio of the composite initiator to perfluoroalkoxycyclohexane was 1:5, and the remaining steps were the same as in Example 1.

[0074] Example 18

[0075] Product A was mixed with adipic acid at a molar ratio of 1:2, and the remaining steps were the same as in Example 1.

[0076] Example 19

[0077] Product A was mixed with adipic acid at a molar ratio of 1:3, and the remaining steps were the same as in Example 1.

[0078] Example 20

[0079] The molar ratio of adipic acid to epichlorohydrin was 1:2, and the remaining steps were the same as in Example 1.

[0080] Example 21

[0081] The molar ratio of adipic acid to epichlorohydrin was 1:3, and the remaining steps were the same as in Example 1.

[0082] Comparative Example 1

[0083] Without adding fluorinated epoxy monomers, the remaining steps are the same as in Example 1.

[0084] Comparative Example 2

[0085] The initiator used was only cashew phenol, and the remaining steps were the same as in Example 1.

[0086] Comparative Example 3

[0087] The initiator does not contain bisphenol F, and the remaining steps are the same as in Example 1.

[0088] Performance testing

[0089] According to SY-T 5281-2000 "Performance Evaluation Method for Crude Oil Demulsifiers (Bottle Test Method)," the performance of demulsifiers was tested using examples and comparative examples as samples. The crude oil was placed in a 30°C water bath and allowed to stand until the crude oil emulsion became fluid. The emulsion was then transferred to a 100 mL colorimetric tube. Residual crude oil on the colorimetric tube was wiped clean with absorbent paper. The entire colorimetric tube was then immersed in the 30°C water bath for preheating for 20 minutes. After preheating, 120 mg / L of demulsifier was added using a syringe, the cap was tightened, and the tube was manually shaken for 3 minutes, at least 100 times. During shaking, the cap was opened to release gas from the tube to prevent the cap from being ejected, ensuring thorough mixing of the demulsifier and the crude oil emulsion. The mixed emulsion was then placed vertically in the water bath to begin the demulsification experiment. Set the time to 25 min, 35 min, and 45 min respectively, record the amount of water removed, and calculate the demulsification rate. The formula for calculating the demulsification rate is: Demulsification rate = Amount of water removed / Water content of crude oil × 100%.

[0090]

[0091] The data from the examples and comparative examples show that the demulsification rate of Comparative Example 1 was only 48.9% at 45 min, a decrease of 45.2% compared to Example 1, demonstrating that perfluoroalkoxycyclohexane can significantly reduce the oil-water interfacial energy and achieve efficient demulsification at low temperatures. The demulsification rates of Comparative Examples 2 and 3 decreased by 38.6% and 31.6%, respectively, indicating that the cashew phenol-polyethylene polyamine-bisphenol F ternary system overcomes the limitations of single initiator performance through the synergy of hydrophobic anchoring, rapid diffusion, and interfacial rigidity.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation, characterized in that, The specific steps of the preparation method are as follows: S1: Cashew nut shell powder, pentaethylene hexamine, and bisphenol F are mixed and added to a reaction vessel. A 30-40 wt% formaldehyde aqueous solution (0.4-0.6% by weight of cashew nut shell powder) is added dropwise. The mixture is reacted at 45-50℃ for 1-2 h. Xylene (1.5-2 times the mass of the formaldehyde aqueous solution) is added, and the mixture is heated to 140-150℃ and refluxed for 2-3 h to obtain the composite initiator. S2: The composite initiator is mixed with potassium hydroxide and added to a reaction vessel. High-purity nitrogen gas and propylene oxide are introduced. The mixture is reacted at 120-125℃ and 0.25-0.35 MPa for 2.5-3 h. S3: Ethylene oxide is introduced into the reaction vessel. The mixture is reacted at 110-120℃ and 0.2-0.3 MPa for 1.5-2.5 h. S4: Add fluorinated epoxy monomer to the reactor and react at a temperature of 105~115℃ and a pressure of 0.15~0.25 MPa for 3~4 h to obtain product A; S5: Mix product A with adipic acid, add epichlorohydrin, and react at a temperature of 120~130℃ and a vacuum of 0.04 MPa for 2~3 h. Dissolve in ethyl acetate, wash with water to remove salt, and distill under reduced pressure to obtain the low-temperature polyether demulsifier for oil and gas gathering and transportation.

2. The method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, In S1, cashew phenol, pentaethylene hexamine and bisphenol F are mixed in a molar ratio of 1:(0.3~0.5):(0.2~0.4).

3. The method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, The amount of potassium hydroxide added in S2 is 3-5% of the mass of the composite initiator.

4. The method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, The molar ratio of the composite initiator to propylene oxide in S2 is 1:(50~60).

5. The method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, The molar ratio of the composite initiator to ethylene oxide is 1:(15~20).

6. The method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, The fluorinated epoxy monomer in S4 includes perfluoroalkoxycyclohexane.

7. The method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, The molar ratio of the composite initiator to the fluorinated epoxy monomer is 1:(3~5).

8. A method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, In S5, product A is mixed with adipic acid in a molar ratio of 1:(2~3).

9. A method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, The molar ratio of adipic acid to epichlorohydrin in S5 is 1:(2~3).

10. A method for preparing a low-temperature polyether demulsifier for oil and gas gathering and transportation according to claim 1, characterized in that, The low-temperature polyether demulsifier obtained in S5 has a molecular weight of 8000~12000 Da, a molecular weight distribution index (PDI) ≤ 1.3, and a fluorine content of 5.5~6.5 wt%.

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