Film-forming thick oil cleaning agent and application thereof

Abstract

The invention discloses a film-forming thick oil cleaning agent and application thereof, and belongs to the technical field of underground working fluid. The heavy oil cleaning agent is composed of a surfactant, an emulsifier and a film-forming agent. And mixing with water to prepare the flushing fluid. According to the invention, the surfactant and the emulsifier are compounded, the film-forming agent is introduced, and a chemical cleaning-chemical film forming combined method is utilized, so that a strong hydrophilic film is formed on the basis of effectively removing thick oil attached to the pipe wall, an oil film is effectively prevented from being secondarily attached to the pipe wall, and the cleaning efficiency is high. The method is suitable for cleaning organic scale of the oil pipe.

Description

Technical Field

[0001] This invention belongs to the field of downhole working fluid technology, and relates to a heavy oil cleaning agent, specifically a film-forming heavy oil cleaning agent and its application. Background Technology

[0002] During oilfield production, as crude oil flows from the bottom of the well to the surface, its temperature gradually decreases, causing heavy components such as paraffin and asphaltene in the crude oil to deposit on the surfaces of the tubing and sucker rods, forming organic scale. The presence of this deposit not only hinders normal well production but can also obstruct other well operations, such as water shut-off or perforation. Therefore, regular well cleaning operations are crucial for maintaining smooth oil well production. The goal of well cleaning is to remove these organic deposits to ensure the production efficiency of the oil well.

[0003] Currently, most oilfields in my country commonly use diesel or other organic cleaning agents in well washing operations. This practice is not only costly but also has a significant environmental impact. The use of organic cleaning agents leads to numerous environmental problems, such as soil and groundwater pollution, and the difficulty of dealing with these harmful chemicals. Furthermore, residual organic solvents on the removed tubing and sucker rods can contaminate the surface well site, increasing the environmental remediation burden. For example, the well washing fluid disclosed in Chinese invention patent application number "CN202110414049.1" contains 30-70% dimethyl ether. In response to these challenges, researchers have focused on efficient and environmentally friendly water-based well washing fluids, conducting extensive research and optimizing the combination of interfacial wetting reversal agents and emulsifiers. However, the cleaning efficiency of current water-based well washing fluids remains low, and they require heating to 80°C or higher before use. Even then, a thick oil film still adheres to the pipe wall after cleaning.

[0004] In conclusion, with the increasing environmental protection requirements of oilfield development and the growing pressure to control operating costs, developing a water-based cleaning agent that is both efficient and environmentally friendly has become an urgent problem for the industry to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a film-forming heavy oil cleaning agent and its application, so as to solve the problems of low cleaning efficiency, high energy consumption and environmental pollution of existing heavy oil cleaning agents.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A film-forming heavy oil cleaning agent, the raw materials for which its active ingredient is made include surfactants, emulsifiers and film-forming agents.

[0008] As a limitation, the surfactant comprises 60%-70% by weight, the emulsifier comprises 15%-20% by weight, and the balance is a film-forming agent.

[0009] As another limitation, the surfactant includes sodium dodecylbenzenesulfonate or sodium dodecyl sulfate; the emulsifier includes Tween 80; and the film-forming agent includes heptadecanylaminoethyl imidazoline quaternary ammonium salt.

[0010] This invention also provides an application of a film-forming heavy oil cleaning agent, which involves mixing water and the film-forming heavy oil cleaning agent to prepare a well-washing fluid.

[0011] As a limitation, the weight ratio of the water to the film-forming heavy oil cleaning agent is 100:1.

[0012] By adopting the above technical solution, the technical progress achieved by this invention compared with the prior art is as follows:

[0013] This invention provides a film-forming heavy oil cleaning agent that utilizes a compound of surfactants and emulsifiers, and introduces a film-forming agent. By combining chemical cleaning with chemical film formation, it effectively removes heavy oil adhering to the pipe wall and forms a strongly hydrophilic film, effectively preventing secondary oil film adhering to the pipe wall. The heavy oil cleaning efficiency reaches over 95%, and it is environmentally friendly as it does not use any environmentally polluting chemical reagents. Detailed Implementation

[0014] The present invention will be further described in detail below through specific embodiments. It should be understood that the described embodiments are only for explaining the present invention and do not limit the present invention.

[0015] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art.

[0016] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0017] Example 1

[0018] This embodiment discloses a film-forming heavy oil cleaning agent, which is composed of 60 wt% sodium dodecyl sulfate, 20 wt% Tween 80 and 20 wt% heptadecenylamine ethyl imidazoline quaternary ammonium salt.

[0019] Example 2

[0020] This embodiment discloses a film-forming heavy oil cleaning agent, which is composed of 70 wt% sodium dodecyl sulfate, 15 wt% Tween 80 and 15 wt% heptadecenylamine ethyl imidazoline quaternary ammonium salt.

[0021] Example 3

[0022] This embodiment discloses a film-forming heavy oil cleaning agent, which is composed of 65 wt% sodium dodecyl sulfate, 15 wt% Tween 80 and 20 wt% heptadecenylamine ethyl imidazoline quaternary ammonium salt.

[0023] Example 4

[0024] This embodiment discloses a film-forming heavy oil cleaning agent, which is composed of 60 wt% sodium dodecylbenzenesulfonate, 18 wt% Tween 80 and 22 wt% heptadecenylamine ethyl imidazoline quaternary ammonium salt.

[0025] Example 5

[0026] This embodiment discloses the application of film-forming heavy oil cleaning agents. Heavy oil cleaning agents of different weight compositions are prepared into well-washing fluids, and heavy oil cleaning experiments are conducted. A control group is also set up to verify the effect. The specific steps include:

[0027] S1. Sample preparation:

[0028] Take one part of the film-forming heavy oil cleaning agent from Examples 1-4 respectively, add 100 parts of water to prepare well washing fluid, and record them as Samples 1-4 respectively;

[0029] Take 1 part of the cleaning agent (composed of 60wt% sodium dodecylbenzenesulfonate, 20wt% OP-20 and 20wt% rutin) and add 100 parts of water to prepare the well washing solution, which is recorded as control sample 1;

[0030] Take 1 part of the cleaning agent (composed of 70 wt% sodium dodecylbenzenesulfonate, 15 wt% OP-20 and 15 wt% hexadecyltrimethylammonium chloride) and add 100 parts of water to prepare the well washing solution, which is recorded as control sample 2.

[0031] Take 1 part of the cleaning agent (composed of 65 wt% sodium dodecylbenzenesulfonate, 15 wt% polyether and 20 wt% butylene) and add 100 parts of water to prepare the well washing solution, which is recorded as control sample 3.

[0032] Take 1 part of the cleaning agent (composed of 60 wt% sodium dodecylbenzenesulfonate, 18 wt% polyether and 22 wt% hexadecyltrimethylammonium chloride) and add 100 parts of water to prepare the well washing solution, which is recorded as control sample 4.

[0033] S2. Heavy Oil Cleaning Efficiency Test

[0034] Thick oil (with a liquefaction stability of 65℃) was applied to the outer cylinder of a six-speed rotational viscometer. The mass of the thick oil was recorded as M1. The viscometer was then placed into samples 1-4 and control samples 1-4 at a temperature of 70℃ and rotated at 200 r / min for 15 minutes. After removing the viscometer, the remaining mass of the thick oil was measured and recorded as M2. The cleaning efficiency formula for the thick oil is:

[0035] Cleaning efficiency = (M1-M2) / M1 × 100%

[0036] The test results are shown in Table 1:

[0037] Table 1. Summary of Heavy Oil Cleaning Efficiency

[0038] Sample number Heavy oil cleaning efficiency Sample 1 100％ Sample 2 97％ Sample 3 98％ Sample 4 95％ Comparison Sample 1 80％ Comparison Sample 2 78％ Comparison Sample 3 75％ Comparison Sample 4 81％

[0039] In this embodiment, surfactants reduce the interfacial tension between oil and water, making it easier to wash heavy oil off the pipe wall; emulsifiers emulsify and solubilize the washed oil, increasing cleaning efficiency; and film-forming agents adsorb and form a film to prevent secondary adhesion of oil. There are many types of film-forming agents, which can be broadly categorized into two types based on their mechanism of action: precipitating agents and adsorbing agents that can pair with metals. Considering only the cleaning efficiency of heavy oil, precipitating film-forming agents are also feasible, but they can contaminate and clog the formation. Therefore, adsorbing film-forming agents are chosen, with imidazoline-based agents being the preferred choice. Imidazolium-based film-forming agents can adsorb onto the pipe wall, forming a strongly hydrophilic film. Other types of film-forming agents, such as rutin, present problems such as difficulty in dissolving and on-site preparation.

[0040] As shown in Table 1, the preferred surfactant, emulsifier and film-forming agent components of this invention can effectively clean heavy oil, while other combinations of emulsifiers or film-forming agents cannot achieve good results. The film-forming heavy oil cleaner provided by this invention has a cleaning efficiency of over 95%.

Claims

1. A film-forming heavy oil cleaning agent, characterized in that, The raw materials used to make its active ingredients include surfactants, emulsifiers, and film-forming agents.

2. The film-forming heavy oil cleaning agent according to claim 1, characterized in that, The surfactant accounts for 60%-70% by weight, the emulsifier accounts for 15%-20%, and the balance is a film-forming agent.

3. A film-forming heavy oil cleaning agent according to claim 1 or 2, characterized in that, The surfactant includes sodium dodecylbenzenesulfonate or sodium dodecyl sulfate; the emulsifier includes Tween 80; and the film-forming agent includes heptadecanylamine ethyl imidazoline quaternary ammonium salt.

4. The application of a film-forming heavy oil cleaning agent, characterized in that, It is prepared by mixing water and film-forming heavy oil cleaning agent.

5. The application of the film-forming heavy oil cleaning agent according to claim 4, characterized in that, The weight ratio of water to film-forming heavy oil cleaning agent is 100:1.