Oil sludge modifying and flooding agent as well as preparation method and application thereof

Abstract

The invention discloses an oil sludge modifying and flooding agent as well as a preparation method and application thereof. The oil sludge modifying and flooding agent comprises the following components in parts by mass: 1-5 parts of oil sludge, 1-5 parts of a sulfonating agent, 0.1-5 parts of an alkali neutralizer and 0.01-3 parts of a surfactant. The oil sludge profile control and displacement agent provided by the invention can obtain good profile control and oil washing effects through the synergistic compounding effect of all the components. On the basis, the sulfonating agent is used for sulfonating crude oil rich in aromatic compounds in the oil sludge, part of the oil sludge is converted into mahogany petroleum sulfonate through alkali neutralization, and after the sulfonating agent is compounded with the surfactant, the oil washing effect of the oil sludge is activated, and meanwhile, fine particles of the oil sludge and residues of sulfonation reaction have certain plugging and profile control effects. Compared with the prior art, the oil sludge profile control and displacement agent provided by the invention can effectively reduce the oil-water interfacial tension on the premise of similar profile control performance; and under the conditions of the same usage amount and the same oil reservoir, the crude oil recovery rate can be increased by 5%.

Description

Technical Field

[0001] The invention relates to an oil sludge displacement agent and a preparation method and application thereof. Background Art

[0002] In oilfield production, sewage treatment systems and crude oil storage and transportation processes will produce a large amount of oily sludge, also known as oil sludge. Oil sludge is essentially an emulsion-like mixture of crude oil produced from the formation, fine particles in the formation, and formation water. Its main components are suspended solids, oil, and water, of which crude oil accounts for 5-30% and water accounts for more than 80%. However, oil sludge also includes various chemical additives and harmful substances such as heavy metals, which can cause serious environmental pollution. Therefore, solid wastes such as oil sludge are listed as hazardous wastes, and sludge must be rendered harmless before discharge.

[0003] With the continuous development of oil fields, the amount of oily sludge is also increasing year by year. At present, the treatment methods of oily sludge at home and abroad mainly include landfill, concentration and dehydration, solidification treatment, chemical oil removal, catalytic cracking, comprehensive utilization (making building materials or making suspended profile control and water plugging agents), flotation oil removal, extraction or biological treatment, etc. However, these methods, on the one hand, are difficult to technically remove the crude oil in the sludge to the ultra-low oil content of solid emissions. On the other hand, during the treatment process, wastewater, waste gas and waste solid will be generated again, which needs to be treated again. The treatment cost is high and the pollution to the ground environment cannot be completely eliminated.

[0004] In recent years, based on the environmental protection concept that oil sludge comes from oil production layers and "returns" to oil production strata, oil sludge is prepared into profile control and flooding agents and injected back into profile control strata, leaving no products on the ground, without environmental risks, and can be used as a resource through profile control and efficiency enhancement. Oil sludge contains 10-30% crude oil, which is highly viscous, high in wax, and mixed with asphalt, showing characteristics such as "heavy crude oil and difficult to flow". In addition, most of the oil sludge is semi-solid and paste-like, and has poor profile control injection. The existing profile control and flooding technology emulsifies and reduces the viscosity of the crude oil in the oil sludge, prepares it into a carrier liquid of the mud and sand particles of the oil sludge itself, improves the rheological injection of the oil sludge, and injects it into the profile control target layer. However, the above method can only improve the fluidity of crude oil from the aspect of physical properties, so that this part of crude oil is injected into the formation together with the mud and sand of the oil sludge itself, and only realizes the physical filling of the formation water injection channel, and the function is relatively single. Summary of the invention

[0005] In order to at least partially solve the above technical problems, the present invention starts from the characteristics of crude oil in oil sludge and realizes efficient utilization of oil sludge flooding performance through chemical modification. The present invention provides a method for chemically modifying crude oil in oil sludge, which can add oil washing capacity to the oil sludge flooding agent, so as to be suitable for the technical development demand of oil sludge profile control and flooding to significantly improve crude oil recovery.

[0006] As one aspect of the present invention, it relates to an oil sludge displacement agent, which comprises the following components by weight: 1 to 5 parts of oil sludge, 1 to 5 parts of sulfonating agent, 0.1 to 5 parts of alkali neutralizing agent, and 0.01 to 3 parts of surfactant.

[0007] By adopting the above technical scheme, the mud and sand of the sludge and the residue after the sludge sulfonation reaction can be used to block the formation water drive channel, and the petroleum sulfonate generated by the sludge sulfonation modification and the various substances of the compounded surfactant can migrate to the secondary pores, affect the oil-bearing parts of the formation, reduce the oil-water interfacial tension, and obtain good profile control and oil washing effects.

[0008] In a specific embodiment, the particle size of the oil sludge does not exceed 50 μm, and the viscosity does not exceed 2000 mPa·s.

[0009] In a specific embodiment, the oil content of the oil sludge is 10-50%.

[0010] In a specific embodiment, the sulfonating agent is selected from one or more of fuming sulfuric acid, concentrated sulfuric acid, liquid sulfur trioxide, and gaseous sulfur trioxide.

[0011] In a specific embodiment, the alkaline neutralizing agent is selected from a sodium hydroxide aqueous solution with a mass concentration of 10 to 30%.

[0012] In a specific embodiment, the surfactant is selected from nonionic surfactants and / or amphoteric surfactants.

[0013] In a specific embodiment, the nonionic surfactant is selected from one or more of alkanolamides, Spans, and Tweens.

[0014] In a specific embodiment, the amphoteric surfactant is selected from betaine type and / or amino acid type.

[0015] As another aspect of the present invention, it relates to a method for preparing the above-mentioned sludge displacement agent, the method comprising the following steps:

[0016] S1. Weigh each component by mass, raise the temperature of the sludge under stirring, and then add a sulfonating agent to obtain a crude sulfonated sludge product;

[0017] S2. Under stirring conditions, add an alkali neutralizer to the crude sulfonated sludge product obtained in S1, then add a surfactant, mix, and cool to obtain an sludge displacement agent.

[0018] In a specific embodiment, in S1, the stirring time is 3 to 10 hours, and the speed is 500 to 1000 rpm.

[0019] In a specific embodiment, in S1, the sludge temperature is increased to 40-60°C.

[0020] In a specific embodiment, in S1, the interval between two adjacent additions of the sulfonating agent is 5 to 10 minutes.

[0021] In a specific embodiment, the amount of the sulfonating agent added each time is 5-10% of the total amount of the sulfonating agent.

[0022] In a specific embodiment, in S2, the stirring time is 0.5 to 1 h, and the speed is 500 to 1000 rpm.

[0023] As another aspect of the present invention, it relates to the application of the above-mentioned sludge displacement control agent in the profile control and displacement control of the oil production layer with water injection channeling.

[0024] The oil sludge control agent provided by the present invention can achieve good profile control and oil washing effects through the synergistic compounding of various components. On this basis, since the sulfonating agent sulfonates the crude oil rich in aromatic compounds in the oil sludge, the conversion of part of the oil sludge into petroleum sulfonate is achieved through alkali neutralization, and after compounding with the surfactant, the oil washing effect of the oil sludge is activated, and at the same time, the fine particles of the oil sludge itself and the residues of the sulfonation reaction have a certain plugging and profile control effect.

[0025] Compared with the prior art, the oil sludge displacement agent provided by the present invention can effectively reduce the oil-water interfacial tension under the premise of similar profile control performance; under the same usage amount and the same reservoir conditions, the crude oil recovery rate can be increased by 5 percentage points.

[0026] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and claims. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific examples, and the protection scope of the present invention is not limited by the following examples. The sources of the materials mainly involved in the examples are shown in Table 1 below, and other materials not shown are conventional commercial products.

[0028] Table 1 Material source description

[0029] Serial number materials Specifications / Models factory 1 Concentrated sulfuric acid WH2SO4 / %≥98% Tianjin Boda Sulfuric Acid Co., Ltd. 2 Oleum WSO3 / %≥20% Tianjin Boda Sulfuric Acid Co., Ltd. 3 Sodium hydroxide Analytical grade Shenzhen Beihua Fine Chemicals Co., Ltd. 4 Dodecyl dimethyl betaine BS-12 Jinan Huize Chemical Co., Ltd. 5 Sodium dodecylaminopropionate Analytical grade Beijing Huameihuli Biochemical 6 Span 60 S-60 Jiangsu Haian Petrochemical Plant 7 Coconut fatty acid diethanolamide 6501 Shandong Chenyu Chemical Co., Ltd. 8 Tween60 T-60 Jiangsu Haian Petrochemical Plant

[0030] The inventor has provided the technical solution of the present invention through a large amount of literature search and experimental research. The following are specific embodiments of the present invention.

[0031] Example 1

[0032] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 50 grams of oil sludge; 10 grams of sulfonating agent; 1 gram of alkali neutralizing agent; and 0.1 gram of surfactant.

[0033] The oil sludge is selected from the area with particle size less than 30 μm, oil content of 15%, and viscosity of 800 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is 10% NaOH aqueous solution; the surfactant includes: 0.06 g of dodecyl dimethyl betaine + 0.04 g of Span 60 surfactant.

[0034] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0035] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 500 rpm, and the sludge is added to the reactor under stirring conditions. When the temperature in the reactor reaches 60°C, the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 5 minutes, and the mass of each sulfonating agent added is 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time is reached for 3 hours, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time is reached for 0.5 hours, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0036] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0037] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 859 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 80%.

[0038] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.107mN / m.

[0039] Example 2

[0040] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 10 grams of oil sludge; 50 grams of sulfonating agent; 50 grams of alkali neutralizing agent; and 30 grams of surfactant.

[0041] The oil sludge is selected from the area with a particle size less than 50 μm, an oil content of 20%, and a viscosity of 2000 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is a 10% NaOH aqueous solution; and the surfactant includes: 20 grams of sodium dodecylaminopropionate + 10 grams of Tween 60 surfactant.

[0042] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0043] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 1000 rpm, and the sludge is added to the reactor under stirring. When the temperature in the reactor reaches 40°C, the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 5 minutes, and the mass of each sulfonating agent added is 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time is reached for 5 hours, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time is reached for 1 hour, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0044] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0045] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 967 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 75%.

[0046] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.006mN / m.

[0047] Example 3

[0048] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 20 grams of oil sludge; 40 grams of sulfonating agent; 40 grams of alkali neutralizing agent; and 20 grams of surfactant.

[0049] The oil sludge is selected from the area with a particle size less than 55 μm, an oil content of 20%, and a viscosity of 1500 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is a 10% NaOH aqueous solution; and the surfactant includes: 12 grams of sodium dodecylaminopropionate + 8 grams of coconut fatty acid diethanolamide surfactant.

[0050] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0051] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 500 rpm, and the sludge is added to the reactor under stirring conditions. When the temperature in the reactor reaches 50° C., the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 10 minutes, and the mass of each sulfonating agent added is 10% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time of 10 hours is reached, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time of 0.5 hours is reached, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0052] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0053] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 855 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 79%.

[0054] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.015mN / m.

[0055] Example 4

[0056] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 40 grams of oil sludge; 20 grams of sulfonating agent; 20 grams of alkali neutralizing agent; and 10 grams of surfactant.

[0057] The oil sludge is selected from the area with a particle size of less than 48 μm, an oil content of 14%, and a viscosity of 1200 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is a 10% NaOH aqueous solution; and the surfactants include: 6 grams of dodecyl dimethyl betaine + 4 grams of Tween 60 surfactant.

[0058] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0059] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 500 rpm, and the sludge is added to the reactor under stirring. When the temperature in the reactor reaches 50°C, the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 5 minutes, and the mass of each sulfonating agent added is 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time is reached for 3 hours, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time is reached for 0.5 hours, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0060] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0061] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 864 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 81%.

[0062] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.065mN / m.

[0063] Example 5

[0064] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 10 grams of oil sludge; 10 grams of sulfonating agent; 1 gram of alkali neutralizing agent; and 0.3 grams of surfactant.

[0065] The oil sludge is selected from the area with a particle size less than 55 μm, an oil content of 12%, and a viscosity of 1000 mPa·s; the sulfonating agent is 20% fuming sulfuric acid; the alkali neutralizing agent is a 10% NaOH aqueous solution; and the surfactant includes: 0.2 g of dodecyl dimethyl betaine + 0.1 g of Tween 60 surfactant.

[0066] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0067] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 1000 rpm, and the sludge is added to the reactor under stirring conditions. When the temperature in the reactor reaches 50°C, the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 5min, and the mass of each sulfonating agent added is 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time is reached for 3h, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time is reached for 0.5h, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0068] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0069] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 951 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 82%.

[0070] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.080mN / m.

[0071] Example 6

[0072] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 50 grams of oil sludge; 50 grams of sulfonating agent; 50 grams of alkali neutralizing agent; and 30 grams of surfactant.

[0073] The oil sludge is selected from the area with a particle size less than 51 μm, an oil content of 28%, and a viscosity of 2000 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is a 10% NaOH aqueous solution; and the surfactant includes 20 grams of sodium dodecylaminopropionate and 10 grams of coconut fatty acid diethanolamide.

[0074] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0075] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 500 rpm, and the sludge is added to the reactor under stirring. When the temperature in the reactor reaches 50°C, the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 5 minutes, and the mass of each sulfonating agent added is 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time is reached for 3 hours, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time is reached for 0.5 hours, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0076] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0077] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 873 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 88%.

[0078] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.053mN / m.

[0079] Example 7

[0080] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 10 grams of oil sludge; 10 grams of sulfonating agent; 50 grams of alkali neutralizing agent; and 30 grams of surfactant.

[0081] The oil sludge is selected from the area with a particle size of less than 45 μm, an oil content of 16%, and a viscosity of 1300 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is a 10% NaOH aqueous solution; and the surfactant includes: 20 grams of dodecyl dimethyl betaine + 10 grams of Tween 60 surfactant.

[0082] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0083] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 1000 rpm, and the sludge is added to the reactor under stirring conditions. When the temperature in the reactor reaches 50°C, the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 5min, and the mass of each sulfonating agent added is 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time is reached for 3h, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time is reached for 0.5h, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0084] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0085] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 902 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 72%.

[0086] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.041mN / m.

[0087] Example 8

[0088] The present embodiment provides an oil sludge control and displacement agent, which includes the following components in parts by weight: 50 grams of oil sludge; 50 grams of sulfonating agent; 10 grams of alkali neutralizing agent; and 10 grams of surfactant.

[0089] The oil sludge is selected from the area with particle size less than 60 μm, oil content of 18% and viscosity of 1000 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is 10% NaOH aqueous solution; the surfactant includes: 6 grams of sodium dodecylaminopropionate + 4 grams of Span 60 surfactant.

[0090] The preparation steps of an oil sludge displacement agent provided in this embodiment are as follows:

[0091] According to the mass fraction of each component in the sludge displacement agent, each substance is weighed; the stirring speed is set to 500 rpm, and the sludge is added to the reactor under stirring. When the temperature in the reactor reaches 50°C, the sulfonating agent is added, and the time interval between two adjacent additions of the sulfonating agent is controlled to be 5 minutes, and the mass of each sulfonating agent added is 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent is completed and the first set stirring time is reached for 3 hours, the alkali neutralizing agent is continued to be added to the reactor. After the second set stirring time is reached for 0.5 hours, a surfactant is added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0092] The control and displacement performance of a sludge control and displacement agent provided in this embodiment is tested, and the test process is as follows:

[0093] (1) Sealing performance: The sealing performance of the sludge profile control agent was simulated using a core flow tester to simulate formation conditions. The test method followed the standard SY / T 7625-2021 Technical Specification for Sludge Profile Control. The test results showed that for a core with a permeability of 897 mD, after injecting 2 PV of a 30% wt sludge profile control agent aqueous solution (prepared with tap water), the core plugging rate was 93%.

[0094] (2) Reducing interfacial tension: The test method follows the standard SY / T 5908-94 petroleum sulfonate performance determination method for oil displacement, and uses a CNG-701 rotating drop tension meter to measure the oil-water interfacial tension in the sludge displacement agent system. First, the sludge displacement agent is diluted to a solution with a concentration of 3.0wt%, and the solution is injected into the capillary tube using a syringe. Then, an oil droplet (from the crude oil produced from the oil layer where the sludge used in this test is located) is injected into the external phase sludge displacement agent using a micro-injector to complete the preparation of the capillary sample tube. Under the simulated formation temperature of 50°C, the oil-water interface is finally stabilized at 0.071mN / m.

[0095] (3) Enhanced oil recovery test: Three sand-filled pipes were connected in parallel, with the same injection end and the same outlet end. The permeabilities of the three sand-filled pipes were 251 millidarcy, 350 millidarcy, and 1280 millidarcy, respectively. The three sand-filled pipes were saturated with crude oil (the crude oil produced from the oil layer where the test sludge was located), and the volume of saturated crude oil V1 of the sand-filled pipe was recorded as 122 mL. Tap water was injected from the injection end at a rate of 5 mL / min until the output fluid at the outlet had a water content of 98%. After starting to inject 2 PV of a 30% wt sludge displacement agent aqueous solution (prepared with tap water), water flooding was started again until the output fluid at the outlet had a water content of 98%, and the test was terminated. The volume of crude oil produced from the outlet was collected as 39 mL V2, and the recovery factor was (V2 / V1)×100%. The recovery factor experimental result was 31.96%.

[0096] In order to further verify the synergistic compounding effect of the above components, the inventors set up the following comparative examples 1 to 3, taking Example 8 as an example.

[0097] Comparative Example 1

[0098] The difference from Example 8 is that the sludge displacement agent consists only of sludge.

[0099] Comparative Example 2

[0100] The difference from Example 8 is that the raw material composition of the sludge displacement agent does not contain a sulfonating agent.

[0101] Comparative Example 3

[0102] The difference from Example 8 is that the raw material composition of the sludge displacement agent does not contain a surfactant.

[0103] The above Comparative Examples 1 to 3 were subjected to the same performance tests as Example 8, and the test results were recorded in Table 2 below.

[0104] Table 2 Performance test results of Example 8 and Comparative Examples 1 to 3

[0105] Example 8 Comparative Example 1 Comparative Example 2 Comparative Example 3 Blockage rate / % 93％ 77％ 79％ 86％ Interfacial tension mN / m 0.071 67 3.554 0.953 Improved oil recovery / % 31.96 18.8 22.84 25.82

[0106] Combining the performance test results in Table 2 and Example 8 and Comparative Examples 1 to 3, we can see that Example 8 and Comparative Example 3 rely on sludge and the residue after sludge sulfonation to plug the high permeability strips, which has a significant advantage in plugging rate compared to Comparative Example 1 and Comparative Example 2 which only rely on the sludge part. Because of the synergistic effect of the petroleum sulfonate generated by the sulfonation of the sludge itself and the compound surfactant, Example 8 has a stronger oil washing ability than Comparative Example 2 which only has the compound surfactant and Comparative Example 3 which only has the petroleum sulfonate generated by the sulfonation of the sludge itself, as shown by the ultra-low oil-water interfacial tension.

[0107] In addition, the oil recovery factor is positively correlated with the swept volume and oil washing capacity of the displacement liquid, and the swept volume is positively correlated with the plugging rate, and the recovery factor of Example 8 is significantly superior to that of the control group. Therefore, under the combined effect, the inventor predicts that: under the same usage amount and the same reservoir conditions, the oil recovery factor can be increased by at least 5 percentage points.

[0108] The above are only preferred feasible embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Various modifications or applications made according to the above embodiments are within the protection scope of this technical solution.

[0109] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. A sludge displacement agent, characterized in that: The composition comprises the following components by weight: 1 to 5 parts of oil sludge, 1 to 5 parts of sulfonating agent, 0.1 to 5 parts of alkali neutralizing agent and 0.01 to 3 parts of surfactant.

2. The oil sludge displacement agent according to claim 1, characterized in that: The particle size of the oil sludge does not exceed 50 μm, and the viscosity does not exceed 2000 mPa·s.

3. The oil sludge displacement agent according to claim 2, characterized in that: The oil content of the oil sludge is 10-50%.

4. The oil sludge displacement agent according to claim 1, characterized in that: The sulfonating agent is selected from one or more of fuming sulfuric acid, concentrated sulfuric acid, liquid sulfur trioxide, and gaseous sulfur trioxide.

5. The oil sludge displacement agent according to claim 1, characterized in that: The alkaline neutralizing agent is selected from a sodium hydroxide aqueous solution with a mass concentration of 10 to 30%.

6. The oil sludge displacement agent according to claim 1, characterized in that: The surfactant is selected from nonionic surfactants and / or amphoteric surfactants.

7. The oil sludge displacement agent according to claim 6, characterized in that: The nonionic surfactant is selected from one or more of alkanolamides, Spans, and Tweens.

8. The oil sludge displacement agent according to claim 6, characterized in that: The amphoteric surfactant is selected from betaine type and / or amino acid type.

9. A method for preparing the oil sludge displacement agent according to claim 1, characterized in that: The following steps are involved: S1. Weigh each component by mass, raise the temperature of the sludge under stirring, and then add a sulfonating agent to obtain a crude sulfonated sludge product; S2. Under stirring conditions, add an alkali neutralizer to the crude sulfonated sludge product obtained in S1, then add a surfactant, mix, and cool to obtain an sludge displacement agent.

10. The method for preparing the oil sludge displacement agent according to claim 9, characterized in that: In S1, the stirring time is 3 to 10 hours, and the speed is 500 to 1000 rpm.

11. The method for preparing the oil sludge displacement agent according to claim 9, characterized in that: In S1, the temperature of the sludge is increased to 40-60°C.

12. The method for preparing the oil sludge displacement agent according to claim 9, characterized in that: In the step S1, the interval between two adjacent additions of the sulfonating agent is 5 to 10 minutes.

13. The method for preparing the oil sludge displacement agent according to claim 12, characterized in that: The amount of the sulfonating agent added each time is 5-10% of the total amount of the sulfonating agent.

14. The method for preparing the oil sludge displacement agent according to claim 9, characterized in that: In S2, the stirring time is 0.5 to 1 h, and the speed is 500 to 1000 rpm.

15. Use of the oil sludge displacement control agent as claimed in any one of claims 1 to 14 in carrying out profile control and displacement control in a petroleum production layer with water injection channeling.