A fracturing and oil displacement integrated thickener, preparation method and application

Abstract

The present invention provides an integrated fracturing and oil recovery thickener, preparation method, and application. This relates to the technical field of fracturing and oil recovery. The present invention introduces a functional monomer obtained by esterification of rhamnosyl ester and CH2=C(R)-COOH during the polymerization reaction. This monomer effectively reduces surface and interfacial tension, allowing the profile control agent to form a uniform, continuous liquid film, preventing proppant aggregation and sedimentation in fractures and improving flowback efficiency. The resulting product has the dual functions of oil recovery and oil recovery, simple construction process, and minimal damage to the formation.

Description

Technical Field

[0001] The present invention relates to the technical field of fracturing and oil recovery, and in particular to an integrated fracturing and oil recovery thickener, a preparation method and applications thereof. Background Art

[0002] In recent years, low-permeability, tight oil and gas reservoirs have been effectively developed. Volume fracturing technology plays a key role in the recovery of these reservoirs, and the "high-fluid volume" method is a common strategy in this process. This method requires fracturing fluids with low viscosity and low damage properties. Furthermore, with the increasing research on the mechanism of imbibition displacement, fracturing fluids also require certain imbibition displacement properties to maximize single-well production. Therefore, the development of a fracturing thickener with imbibition displacement properties is of great practical significance.

[0003] Currently, the oil-displacement-capable fracturing fluid systems used in oilfield fracturing typically combine a thickener and a surfactant to reduce interfacial tension. During operation, these two agents are added to the sand mixer in a specific ratio. This fracturing fluid system is relatively complex to use, requiring additional equipment. The system also requires a wide variety of agents and occupies a large area. Furthermore, for water-sensitive formations, the amount of water injected increases significantly, increasing damage to the formation. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, the present invention aims to provide an integrated fracturing and oil recovery thickener, a preparation method and an application thereof.

[0005] One of the purposes of the present invention is to provide an integrated fracturing and oil recovery thickener, which comprises the following raw materials in parts by weight:

[0006]

[0007]

[0008] Wherein, the structural formula of the functional monomer is shown in Formula I:

[0009]

[0010] Among them, the R group includes -H or C1~C 12 A straight chain or branched alkyl group; m=4-12, n=4-12.

[0011] Preferably, the functional monomer is obtained by reacting rhamnose ester and CH2=C(R)-COOH;

[0012] Preferably, the mass ratio of the rhamnosyl ester to CH2=C(R)-COOH is 4 to 8:1;

[0013] Preferably, the rhamnose ester includes, for example, rhamnose ester with a purity of ≥95% produced by MacLean and / or rhamnose ester with a purity of ≥95% produced by Myrel.

[0014] Preferably, the mass ratio of the acrylamide to the functional monomer is 2 to 5:1.

[0015] Preferably, the solvent oil includes one or more of 3# white oil, 7# white oil, 60# white oil or 100# white oil.

[0016] Preferably, the emulsifier includes one or more of Span-80, AEO-9 or Tween 60.

[0017] Preferably, the cross-linking agent includes N,N-methylenebisacrylamide and / or N,N-vinylbisacrylamide; the initiator includes one or more of ammonium persulfate, potassium persulfate, sodium bisulfite or sodium sulfite.

[0018] A second object of the present invention is to provide a method for preparing an integrated fracturing and oil displacement thickener, the preparation method comprising:

[0019] S1 synthetic functional monomer:

[0020] First, add rhamnosyl ester, initiator, inhibitor and toluene, and heat until they are completely dissolved; then add CH2=C(R)-COOH, raise the temperature to 75-85°C, and wait for CH2=C(R)-COOH to react completely to obtain a functional monomer; wherein the R group includes H or C1-C 12 A straight or branched chain alkyl group;

[0021] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0022] The white oil and the emulsifier are stirred evenly to obtain Agent A; acrylamide, a functional monomer and a cross-linking agent are dissolved in pure water to obtain Agent B; Agent B is poured into Agent A, and an initiator is added after adjusting the pH to 6.8-7.2. The reaction temperature is lowered to 20-25°C to obtain an integrated thickener for fracturing and oil displacement.

[0023] Preferably, the initiator comprises p-toluenesulfonic acid, and the inhibitor comprises hydroquinone.

[0024] Preferably, the molar ratio of p-toluenesulfonic acid, hydroquinone and CH2=C(R)-COOH is 1:1:11; the molar ratio of toluene and CH2=C(R)-COOH is 1.5-2.5:1.

[0025] A third object of the present invention is to provide an integrated fracturing and oil recovery thickener for use in oilfield fracturing.

[0026] Beneficial effects of the present invention:

[0027] The present invention introduces a functional monomer obtained by esterification reaction of rhamnolipid and CH2=C(R)-COOH during the polymerization reaction process. Rhamnolipid is an anionic biosurfactant that can effectively reduce surface interfacial tension. At the same time, the lower surface interfacial tension allows the profile control agent to form a uniform and continuous liquid film, preventing the agglomeration and sedimentation of the proppant in the fracture, making it easier for the fluid to flow back from the fracture, thereby improving the flowback rate.

[0028] The resulting product not only meets the performance requirements of a fracturing thickener, but also achieves an interfacial tension of 0.01 mN / m between the breaker and crude oil, demonstrating excellent oil displacement performance. Furthermore, it can perform both fracturing and oil displacement functions, with a simple construction process and minimal damage to the formation. DETAILED DESCRIPTION

[0029] According to a first aspect of the present invention, a fracturing and oil recovery integrated thickener is provided. The fracturing and oil recovery integrated thickener comprises the following raw materials in parts by weight.

[0030]

[0031] Wherein, the structural formula of the functional monomer is shown in Formula I:

[0032]

[0033] Among them, the R group includes H or C1~C 12 A straight chain or branched alkyl group; m=4-12, n=4-12.

[0034] In the present invention, a functional monomer obtained by esterification of rhamnolipid with CH2=C(R)-COOH is introduced into the polymerization process. Rhamnolipid is an anionic biosurfactant whose molecular structure contains hydrophilic rhamnose groups and hydrophobic fatty acid chains. When the rhamnolipid molecules are arranged at the oil-water interface, the hydrophilic groups face the water phase and the hydrophobic groups face the oil phase, forming a highly elastic and stable interfacial film. This reduces the energy between the oil and water interfaces and lowers the interfacial tension.

[0035] Lower surface tension allows the profile control agent to form a uniform, continuous liquid film, preventing proppants (such as ceramsite) from agglomerating and settling in the fracture. This uniform film distribution reduces the interfacial resistance between the fracturing fluid and the formation fluid, improving the conductivity of the fracture, making it easier for fluid to flow back from the fracture and increasing the flowback rate.

[0036] In the present invention, the weight of the solvent oil is, for example, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts or 35 parts.

[0037] In the present invention, the weight of the emulsifier is, for example, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts.

[0038] In the present invention, the weight of the acrylamide is, for example, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts or 25 parts.

[0039] In the present invention, the weight of the functional monomer is, for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

[0040] In the present invention, the weight of the cross-linking agent is, for example, 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts or 0.10 parts.

[0041] In the present invention, the weight of the initiator is, for example, 0.010 parts, 0.012 parts, 0.014 parts, 0.016 parts, 0.018 parts or 0.020 parts.

[0042] In the present invention, the weight of the pure water is, for example, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts.

[0043] In the present invention, the R group is, for example, -H, -CH3, -CH2CH3, -(CH2)2CH3, -(CH2)3CH3, -(CH2)4CH3, -(CH2)5CH3, -(CH2)6CH3, -(CH2)7CH3, -(CH2)8CH3, -(CH2)9CH3, -(CH2) 10 CH3, -(CH2) 11 CH3, -CH(CH3)2, -CH2CH(CH3)2, -CH2C(CH3)3 or -CH2(CHCH3)2CH3.

[0044] Preferably, the functional monomer includes one or more of the following compounds:

[0045]

[0046] In a preferred embodiment of the present invention, the functional monomer is obtained by reacting rhamnose ester and CH2=C(R)-COOH;

[0047] Preferably, the mass ratio of the rhamnosyl ester to CH2=C(R)-COOH is 4 to 8:1;

[0048] Preferably, the rhamnose ester includes, for example, rhamnose ester with a purity of ≥95% produced by MacLean and / or rhamnose ester with a purity of ≥95% produced by Myrel.

[0049] In the present invention, the mass ratio of the rhamnosyl ester to CH2=C(R)-COOH is, for example, 4:1, 5:1, 6:1, 7:1 or 8:1.

[0050] In a preferred embodiment of the present invention, the mass ratio of acrylamide to functional monomer is 2 to 5:1.

[0051] In the present invention, the mass ratio of acrylamide to functional monomer is, for example, 2:1, 3:1, 4:1 or 5:1.

[0052] In a preferred embodiment of the present invention, the solvent oil includes one or more of 3# white oil, 7# white oil, 60# white oil or 100# white oil.

[0053] In the present invention, the solvent is, for example, 3# white oil, 7# white oil, 60# white oil, 100# white oil, 3# white oil and 7# white oil, 7# white oil and 60# white oil, or a combination of 3# white oil, 7# white oil and 60# white oil.

[0054] In the present invention, the emulsifier is, for example, Span-80, AEO-9, Tween 60, Span-80 and AEO-9, or Span-80 and Tween 60.

[0055] Preferably, the emulsifier includes Span-80 and AEO-9, and the mass ratio of Span-80 to AEO-9 is 1:5.

[0056] In the present invention, the cross-linking agent is, for example, N,N-methylenebisacrylamide, N,N-vinylbisacrylamide, or N,N-methylenebisacrylamide and N,N-vinylbisacrylamide.

[0057] In the present invention, the initiator is, for example, ammonium sulfate, potassium persulfate, sodium bisulfite, sodium sulfite, ammonium sulfate and potassium persulfate, potassium persulfate and sodium bisulfite, sodium bisulfite and sodium sulfite, or a combination of ammonium sulfate, potassium persulfate and sodium bisulfite.

[0058] According to a second aspect of the present invention, a method for preparing an integrated fracturing and oil displacement thickener is provided, the preparation method comprising:

[0059] S1 synthetic functional monomer:

[0060] First, rhamnose ester, initiator, inhibitor and toluene are added and heated until all are dissolved; then, CH2=C(R)-COOH is added and the temperature is raised to 75-85°C until CH2=C(R)-COOH is completely reacted to obtain a functional monomer;

[0061] Among them, the R group includes H or C1~C 12A straight or branched chain alkyl group;

[0062] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0063] The white oil and the emulsifier are stirred evenly to obtain Agent A; acrylamide, a functional monomer and a cross-linking agent are dissolved in pure water to obtain Agent B; Agent B is added to Agent A, and the pH is adjusted to 6.8-7.2, and then an initiator is added. After the reaction temperature is lowered to 20-25°C, an integrated thickener for fracturing and oil displacement is obtained.

[0064] In a preferred embodiment of the present invention, the initiator in step S1 includes p-toluenesulfonic acid, and the polymerization inhibitor includes hydroquinone.

[0065] In a preferred embodiment of the present invention, the molar ratio of p-toluenesulfonic acid, hydroquinone and CH2=C(R)-COOH is 1:1:11; the molar ratio of toluene and CH2=C(R)-COOH is 1.5-2.5:1.

[0066] In the present invention, the molar ratio of toluene and CH2=C(R)-COOH is, for example, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1 or 2.5:1.

[0067] Preferably, the molar ratio of toluene and CH2=C(R)-COOH is 2:1.

[0068] In the present invention, the preparation method of the integrated fracturing and oil displacement thickener is specifically as follows:

[0069] S1 synthetic functional monomer:

[0070] First, excess rhamnosyl ester, initiator p-toluenesulfonic acid, inhibitor hydroquinone and toluene are placed in a three-necked flask equipped with a thermometer, reflux condenser, water separator and stirrer, and the temperature is raised to 55-65°C to dissolve all the compounds;

[0071] Then, CH2=C(R)-COOH is added, the ratio of p-toluenesulfonic acid, hydroquinone and CH2=C(R)-COOH is 1:1:11, the molar ratio of toluene and CH2=C(R)-COOH is 1.5-2.5:1, and the temperature is rapidly raised to 75-85°C and the reaction is continued. After reflux, when the water in the water separator reaches the theoretical water output, CH2=C(R)-COOH is completely reacted to obtain a functional monomer.

[0072] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0073] The white oil and the compound emulsifier are stirred evenly to obtain Agent A; acrylamide, functional monomers and cross-linking agents are dissolved in pure water to obtain Agent B; while stirring, Agent B is slowly poured into Agent A and the pH is adjusted to 6.8-7.2; while stirring, an initiator is added, and the temperature is raised to 75-85°C and then lowered to 20-25°C, and the reaction is completed to obtain an integrated thickener for fracturing and oil displacement.

[0074] In the present invention, the theoretical water output refers to the esterification reaction between rhamnose ester and CH2=C(R)-COOH to remove one water molecule, and the molar ratio of water molecule to CH2=C(R)-COOH is 1:1.

[0075]

[0076] A third object of the present invention is to provide an application of the above-mentioned integrated fracturing and oil recovery thickener in oil field fracturing.

[0077] Example 1

[0078] S1 synthetic functional monomer:

[0079] First, 30 g of rhamnose ester, 1.5 g of initiator p-toluenesulfonic acid, 1.0 g of inhibitor hydroquinone and 20 mL of toluene were placed in a three-necked flask equipped with a thermometer, reflux condenser, water separator and stirrer, and the temperature was raised to 60°C to dissolve all the compounds;

[0080] Then, 7 g of CH2CHCOOH was added, and the temperature was quickly raised to 80°C and the reaction was continued. After reflux, the esterification reaction was completed when the water in the water separator reached the theoretical water output of 1.74 mL, and the structural formula of the functional monomer was shown in Formula II:

[0081]

[0082] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0083] A mixture of 30 parts of 3# white oil, 1.7 parts of Span-80, and 8.3 parts of AEO-9 was uniformly stirred to obtain Agent A; 25 parts of acrylamide, 5 parts of functional monomer rhamnosyl acrylate, and 0.1 part of N,N-methylenebisacrylamide were dissolved in 15 parts of pure water to obtain Agent B; while stirring, Agent B was slowly poured into Agent A, and the pH was adjusted to 7; while stirring, 0.01 parts of ammonium persulfate and 0.01 parts of sodium bisulfite were added, and the temperature was raised to 80°C and then lowered to room temperature, and the reaction was completed to obtain an integrated thickener for fracturing and oil recovery.

[0084] Example 2

[0085] S1 synthetic functional monomer:

[0086] In step S1-2, 8.3 g of CH2CCH3COOH was added, and the remaining steps and parameters were the same as in Example 1, to obtain a functional monomer having the structural formula shown in Formula III:

[0087]

[0088] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0089] In step S2, 5 parts of the functional monomer rhamnosyl methacrylate were added, and the remaining steps and parameters were the same as those in Example 1 to obtain an integrated fracturing and oil recovery thickener.

[0090] Example 3

[0091] S1 synthetic functional monomer:

[0092] In step S1-2, 9.6 g of CH2CCH2CH3COOH was added, and the remaining steps and parameters were the same as in Example 1, to obtain a functional monomer having the structural formula shown in Formula IV:

[0093]

[0094] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0095] In step S2, 5 parts of the functional monomer rhamnosyl ethyl acrylate were added, and the remaining steps and parameters were the same as those in Example 1 to obtain an integrated fracturing and oil recovery thickener.

[0096] Example 4

[0097] S1 synthetic functional monomer:

[0098] In step S1-2, 11.0 g of CH2CCH2CH2CH3COOH was added, and the remaining steps and parameters were the same as in Example 1 to obtain the functional monomer V shown below:

[0099]

[0100] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0101] In step S2, 5 parts of the functional monomer rhamnosyl propyl acrylate were added, and the remaining steps and parameters were the same as those in Example 1 to obtain an integrated fracturing and oil recovery thickener.

[0102] Example 5

[0103] S1 synthetic functional monomer:

[0104] In step S1, 23.0 g CH2C(CH2) was added 11CH3COOH, the remaining steps and parameters are consistent with Example 1, and the structure of the functional monomer is shown in Formula VII:

[0105]

[0106] Synthesis of S2 integrated thickener for fracturing and oil recovery:

[0107] In step S2, 5 parts of the functional monomer rhamnosyl dodecyl acrylate were added, and the remaining steps and parameters were the same as those in Example 1 to obtain an integrated fracturing and oil recovery thickener.

[0108] Comparative Example 1

[0109] A mixture of 30 parts of 3# white oil, 1.7 parts of Span-80 and 8.3 parts of AEO-9 was stirred uniformly to obtain Agent A;

[0110] Dissolve 25 parts of acrylamide and 0.1 parts of N,N-methylenebisacrylamide in 15 parts of pure water to obtain Agent B;

[0111] While stirring, slowly pour Agent B into Agent A and adjust the pH to 7;

[0112] Under stirring, 0.01 parts of ammonium persulfate and 0.01 parts of sodium bisulfite were added, and the temperature was raised to 80° C. and then lowered to room temperature, and the reaction was completed to obtain an integrated thickener for fracturing and oil recovery.

[0113] Performance Testing

[0114] Industry Standard / National Standard / Test Method

[0115] Table 2 Performance test results of integrated fracturing and oil recovery thickener

[0116]

Claims

1. A fracturing and oil displacement integrated thickener, characterized in that: The invention comprises the following raw materials in parts by weight: 30~35 parts solvent oil 10-15 parts of emulsifier 20-25 parts of acrylamide 5~10 parts of functional monomer Cross-linking agent 0.05~0.1 parts 0.01~0.02 parts of initiator, and 10-15 parts of pure water; Wherein, the structural formula of the functional monomer is shown in Formula I: Among them, the R group includes H or C1~C 12 A straight chain or branched alkyl group; m=4~12, n=4~12.

2. The integrated fracturing and oil displacement thickener according to claim 1, characterized in that: The functional monomer is obtained by reacting rhamnosyl ester and CH2=C(R)-COOH; wherein the R group includes H or C1~C 12 A straight or branched chain alkyl group; The mass ratio of the rhamnosyl ester to CH2=C(R)-COOH is 4-8:1; The rhamnose esters include rhamnose esters with a purity of ≥95% produced by MacLean and / or rhamnose esters with a purity of ≥95% produced by Myrel.

3. The integrated fracturing and oil displacement thickener according to claim 1, characterized in that: The mass ratio of the acrylamide to the functional monomer is 2-5:

1.

4. The integrated fracturing and oil displacement thickener according to claim 1, characterized in that: The solvent oil includes one or more of 3# white oil, 7# white oil, 60# white oil or 100# white oil.

5. The integrated fracturing and oil displacement thickener according to claim 1, characterized in that: The emulsifier includes one or more of Span-80, AEO-9 or Tween 60.

6. The integrated fracturing and oil displacement thickener according to claim 1, characterized in that: The cross-linking agent includes N,N-methylenebisacrylamide and / or N,N-vinylbisacrylamide; the initiator includes one or more of ammonium persulfate and potassium persulfate.

7. The method for preparing the integrated fracturing and oil displacement thickener according to any one of claims 1 to 6, wherein: The preparation method comprises: S1 synthetic functional monomer: First, add rhamnose ester, initiator, inhibitor and toluene, and heat until they are completely dissolved; then add CH2=C(R)-COOH, raise the temperature to 75-85°C, and wait until CH2=C(R)-COOH is completely reacted to obtain a functional monomer; Among them, the R group includes H or C1~C 12 A straight or branched chain alkyl group; Synthesis of S2 integrated thickener for fracturing and oil recovery: The white oil and the emulsifier are stirred evenly to obtain Agent A; acrylamide, a functional monomer and a cross-linking agent are dissolved in pure water to obtain Agent B; Agent B is added to Agent A, and the pH is adjusted to 6.8-7.2, and then an initiator is added. After the reaction temperature is lowered to 20-25°C, an integrated thickener for fracturing and oil recovery is obtained.

8. The method for preparing an integrated fracturing and oil displacement thickener according to claim 7, wherein: In step S1, the initiator includes p-toluenesulfonic acid, and the polymerization inhibitor includes hydroquinone.

9. The method for preparing an integrated fracturing and oil displacement thickener according to claim 8, wherein: The molar ratio of p-toluenesulfonic acid, hydroquinone and CH2=C(R)-COOH is 1:1:11; the molar ratio of toluene and CH2=C(R)-COOH is 1.5~2.5:

1.

10. Use of the integrated fracturing and oil recovery thickener according to any one of claims 1 to 6 in oilfield fracturing.

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