Fracturing cleanup aid, preparation method and application thereof

Abstract

The application provides a fracturing cleanup aid, a preparation method and application thereof, and belongs to the technical field of oilfield development. The polyoxyethylene type nonionic surfactant in the fracturing cleanup aid has very high surface activity, high stability, and can improve the overall stability of the cleanup aid system; the amide type nonionic surfactant can be compatible with various surfactants, and can be completely dissolved in different types of additives, thereby reducing the surface tension and interfacial tension. The application utilizes the synergistic effect of different nonionic surfactants to greatly reduce the surface tension and interfacial tension of the cleanup aid, and improve the flowback effect of the fracturing fluid. The compounding of lignosulfonate and rosin sulfonate can significantly improve the surface activity, thereby further reducing the surface tension. The fracturing cleanup aid provided by the application has low surface tension (25 DEG C, < 21 mN / m) and low interfacial tension (25 DEG C, < 0.25 mN / m).

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield development, and particularly relates to a fracturing cleanup aid, a preparation method and application thereof. BACKGROUND

[0002] Fracturing is an important measure for reservoir reconstruction of low-permeability and ultra-low-permeability oil and gas reservoirs, and is a leading technology for effective development of tight oil and gas reservoirs. During acidizing and fracturing of an oil well, well flowback fluid needs to be quickly discharged to the ground surface, and in general, the well flowback fluid is quickly discharged to the ground surface by relying on the pressure of the formation itself. When the pressure of the formation gradually decreases, the flowback speed of the well flowback fluid is significantly reduced, and after residues in the well flowback fluid are precipitated, the residues will cause plugging of the bottom layer, resulting in secondary pollution of the formation and affecting the construction progress and efficiency. In order to solve the problem of difficult flowback of well flowback fluid after acidizing and fracturing of an oil layer, using a cleanup aid is a conventional means.

[0003] The cleanup aid is a chemical that can help work residues in the process of acidizing and fracturing to flow back from the formation, and it can reduce the surface tension and interfacial tension of fracturing fluid, increase the flowback energy of the flowback fluid, and reduce the damage of the fracturing fluid to the formation. Therefore, it is of important practical significance to find a fracturing cleanup aid that can significantly reduce the surface tension and interfacial tension, improve the flowback rate of fracturing fluid, and reduce the water sensitivity and water lock damage of the fracturing fluid to the reservoir. SUMMARY

[0004] The present application aims to provide a fracturing cleanup aid, a preparation method and application thereof, which can significantly reduce the surface tension and interfacial tension, thereby improving the flowback rate of fracturing fluid.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a fracturing cleanup aid, which comprises the following preparation raw materials in mass fractions:

[0007] 30-50 parts of polyoxyethylene nonionic surfactant, 10-30 parts of amide nonionic surfactant, 20-30 parts of lignin sulfonate, 20-30 parts of rosin sulfonate, and 50-60 parts of low-molecular alcohol.

[0008] Preferably, the polyoxyethylene nonionic surfactant comprises alkylphenol polyoxyethylene ether, polyoxyethylene fatty alcohol ether or fatty acid polyoxyethylene ether.

[0009] Preferably, the fatty acid polyoxyethylene ether is one or more of SG-40, SG-50 and SG-100.

[0010] Preferably, the amide nonionic surfactant is 6501 surfactant.

[0011] Preferably, the low molecular alcohol includes glycerol or methanol.

[0012] The application provides a preparation method of the fracturing cleanup aid.

[0013] The polyoxyethylene nonionic surfactant, the amide nonionic surfactant, the lignin sulfonate, the rosin sulfonate and the low molecular alcohol are mixed to obtain the fracturing cleanup aid.

[0014] Preferably, the mixing is performed under stirring, and the stirring speed is 100-150 rpm.

[0015] Preferably, the mixing temperature is 50-65 DEG C.

[0016] Preferably, the mixing time is 1-3 h.

[0017] The application provides application of the fracturing cleanup aid or the fracturing cleanup aid prepared by the preparation method in oilfield exploitation.

[0018] The polyoxyethylene nonionic surfactant has extremely high surface activity, can reduce the solution surface tension to an extremely low level, has high stability and can improve the overall stability of the cleanup aid system; the amide nonionic surfactant can be compatible with various surfactants, can be completely dissolved in different additives, thereby reducing the surface tension and the interfacial tension. The polyoxyethylene nonionic surfactant and the amide nonionic surfactant are compounded to produce a synergistic effect, can greatly reduce the surface tension and the interfacial tension of the cleanup aid and improve the cleanup effect of the fracturing fluid. The lignin sulfonate and the rosin sulfonate are compounded to significantly improve the surface activity, thereby further reducing the surface tension. The fracturing cleanup aid provided by the application has low surface tension (25 DEG C, < 21 mN / m) and low interfacial tension (25 DEG C, < 0.25 mN / m).

[0019] The preparation steps of the fracturing cleanup aid are simple, the raw materials are simple and the performance of the cleanup aid system is stable.

[0020] The fracturing cleanup aid has good compatibility with the fracturing fluid, and after compounding, the performance of the fracturing fluid is not affected. DETAILED DESCRIPTION

[0021] The application provides a fracturing cleanup aid, which comprises the following preparation raw materials in mass fractions:

[0022] 30-50 parts of polyoxyethylene nonionic surfactant, 10-30 parts of amide nonionic surfactant, 20-30 parts of lignin sulfonate, 20-30 parts of rosin sulfonate, 50-60 parts of low molecular alcohol.

[0023] Unless otherwise specified, the raw materials used in the present application are all commercially available products well known in the art.

[0024] The raw materials for preparing the cleanup aid for fracturing provided by the present application include 30-50 parts, preferably 35-55 parts, more preferably 40-50 parts of polyoxyethylene nonionic surfactant, in terms of mass parts. In the present application, the polyoxyethylene nonionic surfactant preferably includes alkyl phenol polyoxyethylene ether, polyoxyethylene fatty alcohol ether or fatty acid polyoxyethylene ether; the fatty acid polyoxyethylene ether preferably is one or more of SG-40, SG-50 and SG-100, and when the fatty acid polyoxyethylene ether is two or more of the above, the present application does not have a special limitation on the ratio of different types of fatty acid polyoxyethylene ether, which can be adjusted according to actual needs.

[0025] The raw materials for preparing the cleanup aid for fracturing provided by the present application include 10-30 parts, preferably 15-28 parts, more preferably 20-25 parts, further preferably 22-23 parts of amide nonionic surfactant, in terms of mass parts of the polyoxyethylene nonionic surfactant. In the present application, the amide nonionic surfactant is preferably 6501 surfactant.

[0026] The raw materials for preparing the cleanup aid for fracturing provided by the present application include 20-30 parts, preferably 22-28 parts, more preferably 23-26 parts, further preferably 24-25 parts of lignin sulfonate, in terms of mass parts of the polyoxyethylene nonionic surfactant.

[0027] The raw materials for preparing the cleanup aid for fracturing provided by the present application include 20-30 parts, preferably 22-28 parts, more preferably 23-26 parts, further preferably 24-25 parts of rosin sulfonate, in terms of mass parts of the polyoxyethylene nonionic surfactant. The present application does not have a special limitation on the rosin sulfonate, which can be prepared according to the preparation method well known in the art or obtained in a well known manner.

[0028] The raw materials for preparing the cleanup aid for fracturing provided by the present application include 50-60 parts, preferably 52-58 parts, more preferably 53-56 parts, further preferably 54-55 parts of low molecular alcohol, in terms of mass parts of the polyoxyethylene nonionic surfactant. In the present application, the low molecular alcohol preferably includes glycerol or methanol.

[0029] The application provides a preparation method of the fracturing cleanup aid.

[0030] The polyoxyethylene type nonionic surfactant, the amide type nonionic surfactant, the lignin sulfonate, the rosin-based sulfonate and the low-molecular alcohol are mixed to obtain the fracturing cleanup aid.

[0031] The application does not have special limitation on the adding sequence of the raw materials in the mixing process, and the raw materials can be mixed uniformly according to the process known in the art.

[0032] In the application, the mixing is preferably carried out under stirring, and the rotating speed of the stirring is preferably 100-150 rpm, and more preferably 110-130 rpm.

[0033] In the application, the temperature of the mixing is preferably 50-65 ℃, and more preferably 55-60 ℃, and the time of the mixing is preferably 1-3 h, and more preferably 1.5-2.5 h.

[0034] The application provides application of the fracturing cleanup aid or the fracturing cleanup aid prepared by the preparation method in oilfield exploitation.

[0035] The technical solutions provided by the application will be described in detail below in combination with examples, but they should not be understood as limitations on the protection scope of the application.

[0036] In the following examples, the rosin-based sulfonate is prepared according to the method recorded in the prior art (Synthesis and Performance of Rosin-based Sulfonate Surfactant, Jia Weihong, Biomass Chemical Engineering, 2008, (No. 4)).

[0037] Example 1

[0038] The fracturing cleanup aid provided in the example is prepared from the following raw materials: 30 parts of polyoxyethylene type nonionic surfactant (alkyl phenol polyoxyethylene ether), 15 parts of amide type nonionic surfactant (6501 surfactant), 25 parts of lignin sulfonate, 25 parts of rosin-based sulfonate and 60 parts of low-molecular alcohol (glycerol).

[0039] The preparation method is that the above raw materials are sequentially added into a mixing tank, mixed at 60 ℃ for 2 h under the stirring condition of 150 rpm, and the fracturing cleanup aid is obtained.

[0040] Example 2

[0041] The fracturing cleanup aid provided by the embodiment is prepared from the following raw materials: 35 parts of polyoxyethylene nonionic surfactant (polyoxyethylene fatty alcohol ether), 10 parts of amide nonionic surfactant (6501 surfactant), 20 parts of lignin sulfonate, 20 parts of rosin sulfonate, and 55 parts of low-molecular alcohol (methanol).

[0042] The preparation method comprises sequentially adding the above raw materials into a mixing tank, mixing at 65°C for 3h under the condition of stirring at 130rpm to obtain the fracturing cleanup aid.

[0043] Example 3

[0044] The fracturing cleanup aid provided by the embodiment is prepared from the following raw materials: 40 parts of polyoxyethylene nonionic surfactant (fatty acid polyoxyethylene ether SG-40), 20 parts of amide nonionic surfactant (6501 surfactant), 30 parts of lignin sulfonate, 30 parts of rosin sulfonate, and 55 parts of low-molecular alcohol (glycerol).

[0045] The preparation method comprises sequentially adding the above raw materials into a mixing tank, mixing at 55°C for 3h under the condition of stirring at 120rpm to obtain the fracturing cleanup aid.

[0046] Example 4

[0047] The fracturing cleanup aid provided by the embodiment is prepared from the following raw materials: 50 parts of polyoxyethylene nonionic surfactant (fatty acid polyoxyethylene ether SG-50), 25 parts of amide nonionic surfactant (6501 surfactant), 30 parts of lignin sulfonate, 25 parts of rosin sulfonate, and 60 parts of low-molecular alcohol (glycerol).

[0048] The preparation method comprises sequentially adding the above raw materials into a mixing tank, mixing at 65°C for 1h under the condition of stirring at 150rpm to obtain the fracturing cleanup aid.

[0049] Example 5

[0050] The fracturing cleanup aid provided by the embodiment is prepared from the following raw materials: 45 parts of polyoxyethylene nonionic surfactant (fatty acid polyoxyethylene ether SG-100), 25 parts of amide nonionic surfactant (6501 surfactant), 30 parts of lignin sulfonate, 30 parts of rosin sulfonate, and 55 parts of low-molecular alcohol (methanol).

[0051] The preparation method comprises sequentially adding the above raw materials into a mixing tank, mixing at 50°C for 1h under the condition of stirring at 130rpm to obtain the fracturing cleanup aid.

[0052] Comparative Example 1

[0053] The difference from Example 1 is that no amide nonionic surfactant is added.

[0054] Comparative Example 2

[0055] The difference from Example 1 is only that no rosin sulfonate is added.

[0056] Comparative Example 3

[0057] The difference from Example 1 is only that no lignin sulfonate is added.

[0058] Performance test

[0059] According to QSY 17376-2017 Acidizing Fracturing Cleanup Agent Technical Specification and SY_T 5755-1995 Performance Evaluation of Cleanup Agent for Fracturing Acidizing, the surface tension and interfacial tension of the cleanup agents of Examples 1-5 and Comparative Examples 1-3 are compared, the sample concentration is 0.5% by mass percentage, the test temperature is 25℃, and the test results are shown in Table 1.

[0060] Table 1 Surface tension and interfacial tension of the cleanup agents of Examples 1-5 and Comparative Examples 1-3

[0061] Case Surface tension (mN / m) Interfacial tension (mN / m) Flowback rate (%) Example 1 20.32 0.20 29 Example 2 20.36 0.21 28.6 Example 3 20.53 0.23 27.5 Example 4 20.65 0.22 28.2 Example 5 20.80 0.24 27.2 Comparative Example 1 21.2 0.52 23.2 Comparative Example 2 21.3 0.46 24.3 Comparative Example 3 21.1 0.53 23.1

[0062] As can be seen from Table 1, the cleanup agent for fracturing provided by the present application can significantly reduce the surface tension of water and the interfacial tension between oil and water, which is more conducive to improving the flowback effect of fracturing fluid, thereby reducing the damage to the formation. In addition, according to the comparison of Examples 1-5 and Comparative Examples 1-3, the present application further reduces the interfacial tension and surface tension through the synergistic effect of polyoxyethylene nonionic surfactant, amide nonionic surfactant, lignin sulfonate and rosin sulfonate, and improves the flowback effect of the cleanup agent for fracturing.

[0063] The above is only the preferred embodiment of the present application, and it should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A cleanup aid for fracturing, characterized in that, The raw materials are prepared in mass parts: 30-50 parts of polyoxyethylene nonionic surfactant, 10-30 parts of amide nonionic surfactant, 20-30 parts of lignin sulfonate, 20-30 parts of rosin sulfonate, 50-60 parts of low molecular alcohol; The polyoxyethylene nonionic surfactant is polyoxyethylene fatty alcohol ether; The amide nonionic surfactant is 6501 surfactant; The low molecular alcohol is glycerol or methanol.

2. The method of preparing the cleanup agent for fracturing according to claim 1, characterized in that, The method comprises the following steps: Mixing polyoxyethylene nonionic surfactant, amide nonionic surfactant, lignin sulfonate, rosin sulfonate and low molecular alcohol to obtain a fracturing cleanup aid.

3. The preparation method according to claim 2, characterized in that, The mixing is carried out under stirring, and the stirring speed is 100-150 rpm.

4. The production method according to claim 2, characterized by, The mixing temperature is 50-65℃.

5. The production method according to claim 2 or 4, characterized by, The mixing time is 1-3 h.

6. Application of the fracturing cleanup aid of claim 1 or the fracturing cleanup aid prepared by the method of any one of claims 2-5 in oilfield exploitation.