A kind of oil sludge displacement agent and its preparation method and application

Abstract

The present invention discloses an oil sludge control and displacement agent, as well as its preparation method and application. The oil sludge control and displacement agent comprises the following components, measured by mass: 1 to 5 parts of oil sludge, 1 to 5 parts of a sulfonating agent, 0.1 to 5 parts of an alkali neutralizing agent, and 0.01 to 3 parts of a surfactant. The oil sludge control and displacement agent provided by the present invention can achieve excellent profile control and oil washing effects through the synergistic compounding of the various components. Furthermore, since the sulfonating agent sulfonates the crude oil rich in aromatic compounds in the oil sludge, a portion of the oil sludge is converted into petroleum sulfonates through alkali neutralization. After compounding with the surfactant, the oil sludge's oil washing function is activated. At the same time, the fine particles in the oil sludge itself and the residues from the sulfonation reaction have a certain sealing and profile control effect. Compared with the existing technology, the oil sludge control and displacement agent provided by the present invention can effectively reduce the oil-water interfacial tension while maintaining similar profile control performance. At the same usage amount and under the same reservoir conditions, it can increase the crude oil recovery rate by 5 percentage points.

Description

Technical Field

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

[0002] During oilfield production, wastewater treatment systems and crude oil storage and transportation generate large amounts 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, with crude oil accounting for 5-30% and water accounting for over 80%. However, oil sludge also contains various chemical additives and harmful substances such as heavy metals, which can cause serious environmental pollution. Therefore, solid wastes such as oil sludge are classified as hazardous wastes and must be treated before discharge.

[0003] With the continuous development of oil fields, the amount of oily sludge is also increasing annually. Currently, the main methods for treating oily sludge at home and abroad include landfill, concentration and dehydration, solidification treatment, chemical oil removal, catalytic cracking, comprehensive utilization (for manufacturing building materials or suspended profile control and water plugging agents), flotation oil removal, extraction, or biological treatment. However, these methods are technically difficult to remove crude oil from the sludge to the ultra-low oil content of solid emissions. Moreover, the treatment process also generates secondary wastewater, waste gas, and waste solids that require further treatment, resulting in high treatment costs and inability to completely eliminate pollution to the surface environment.

[0004] In recent years, based on the environmentally friendly concept of "returning" oil sludge to the oil-producing formation, oil sludge has been prepared into profile control and flooding agents for reinjection into the formation. This method leaves no surface residue, eliminates environmental risks, and simultaneously achieves resource utilization through profile control and efficiency enhancement. Oil sludge contains 10-30% crude oil, which is highly viscous, high in wax, and mixed with asphalt, resulting in characteristics such as "heavy crude oil and difficult to flow." Furthermore, most oil sludge is semi-solid and paste-like, resulting in poor injectability for profile control. Existing profile control and flooding technologies emulsify and reduce the viscosity of the crude oil in the sludge, creating a carrier fluid for the sludge's own mud and sand particles. This improves the rheological injectability of the sludge and allows injection into the target formation for profile control. However, these methods only improve the crude oil's physical fluidity, allowing this crude oil to be injected into the formation along with the sludge's own mud and sand, essentially physically filling the formation's injection channels and providing a relatively limited function. 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 the efficient utilization of oil sludge displacement 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 oil sludge displacement agents, so as to be suitable for the technical development demand of oil sludge profile control and displacement 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, calculated by mass: 1 to 5 parts of oil sludge, 1 to 5 parts of a sulfonating agent, 0.1 to 5 parts of an alkali neutralizing agent, and 0.01 to 3 parts of a surfactant.

[0007] By adopting the above technical solution, 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. The petroleum sulfonate generated by the sulfonation modification of the sludge and the various substances of the compounded surfactant can migrate to the secondary channels, 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, which comprises the following steps:

[0016] S1. Weigh each component by mass, raise the temperature of the sludge while 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 prepared in S1, then add a surfactant, mix, and cool to obtain an oil 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 hour, 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 performing profile control and displacement control in a petroleum production layer with water injection channeling.

[0024] The oil sludge displacement agent provided by the present invention achieves excellent profile control and oil washing effects through the synergistic combination of its components. Furthermore, the sulfonating agent sulfonates the aromatic compound-rich crude oil in the oil sludge, converting some of the sludge into petroleum sulfonates through alkali neutralization. This, combined with the surfactant, activates the oil washing function of the sludge. Furthermore, the fine particles in the sludge itself and the residue from the sulfonation reaction provide a certain degree of sealing and profile control.

[0025] Compared with the existing technology, the oil sludge displacement agent provided by the present invention can effectively reduce the oil-water interfacial tension while maintaining similar profile control performance; at the same usage amount and under the same reservoir conditions, it can increase the crude oil recovery rate by 5 percentage points.

[0026] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The objectives 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 will be further described below with reference to specific examples, but the scope of protection 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 fuming sulfuric acid WSO3 / %≥20% Tianjin Boda Sulfuric Acid Co., Ltd. 3 Sodium hydroxide analytically pure Shenzhen Beihua Fine Chemicals Co., Ltd. 4 Dodecyl dimethyl betaine BS-12 Jinan Huize Chemical Co., Ltd. 5 Sodium laurylaminopropionate analytically pure Beijing Huamei Huli Biochemical 6 Span 60 S-60 Jiangsu Hai'an Petrochemical Plant 7 Coconut fatty acid diethanolamide 6501 Shandong Chenyu Chemical Co., Ltd. 8 Tween60 T-60 Jiangsu Hai'an Petrochemical Plant

[0030] The inventors have provided the technical solution of the present invention through extensive literature search and experimental research. The following are specific embodiments of the present invention.

[0031] Example 1

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

[0033] The oil sludge is selected from an area with a particle size of less than 30 μm, an oil content of 15%, and a viscosity of 800 mPa·s; the sulfonating agent is 98% concentrated sulfuric acid; the alkali neutralizing agent is a 10% NaOH aqueous solution; and the surfactants include: 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 was weighed; the stirring speed was set to 500 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 60° C., the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 5 minutes, and the mass of each sulfonating agent added was 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 3 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 0.5 hours was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0036] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0037] (1) Channeling performance: The channeling 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 a 2PV 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system is measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent is diluted to a 3.0 wt% solution. This solution is injected into a capillary tube using a syringe. Then, a microinjector is used to inject an oil droplet (from the crude oil produced in the reservoir where the sludge used in this test is located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface ultimately stabilizes at 0.107 mN / m.

[0039] Example 2

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

[0041] The oil sludge is selected from an area with a particle size of 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 was weighed; the stirring speed was set to 1000 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 40°C, the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 5 minutes, and the mass of each sulfonating agent added was 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 5 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 1 hour was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0044] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0045] (1) Channeling performance: The channeling 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system is measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent is diluted to a 3.0 wt% solution. This solution is injected into a capillary tube using a syringe. Then, a microinjector is used to inject an oil droplet (from the crude oil produced in the oil reservoir where the sludge used in this test is located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface ultimately stabilizes at 0.006 mN / m.

[0047] Example 3

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

[0049] The oil sludge is selected from an area with a particle size of 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 laurylaminopropionate + 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 was weighed; the stirring speed was set to 500 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 50° C., the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 10 minutes, and the mass of each sulfonating agent added was 10% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 10 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 0.5 hours was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0052] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0053] (1) Channeling performance: The channeling 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system is measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent is diluted to a 3.0 wt% solution. This solution is injected into a capillary tube using a syringe. Then, a microinjector is used to inject an oil droplet (from the crude oil produced in the oil reservoir where the sludge used in this test is located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface ultimately stabilizes at 0.015 mN / m.

[0055] Example 4

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

[0057] The oil sludge is selected from an 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 alkaline 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 was weighed; the stirring speed was set to 500 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 50° C., the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 5 minutes, and the mass of each sulfonating agent added was 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 3 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 0.5 hours was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0060] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0061] (1) Channeling performance: The channeling 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 2PV 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system was measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent was diluted to a 3.0 wt% solution, which was injected into a capillary tube using a syringe. Then, a microinjector was used to inject an oil droplet (from the crude oil produced in the reservoir where the sludge used in this test was located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface finally stabilized at 0.065 mN / m.

[0063] Example 5

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

[0065] The oil sludge is selected from an area with a particle size of 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 was weighed; the stirring speed was set to 1000 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 50° C., the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 5 minutes, and the mass of each sulfonating agent added was 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 3 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 0.5 hours was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0068] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0069] (1) Channeling performance: The channeling 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 a 2PV 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system is measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent is diluted to a 3.0 wt% solution, which is injected into a capillary tube using a syringe. Then, a microinjector is used to inject an oil droplet (from the crude oil produced in the reservoir where the sludge used in this test is located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface ultimately stabilizes at 0.080 mN / m.

[0071] Example 6

[0072] This 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 a sulfonating agent; 50 grams of an alkali neutralizing agent; and 30 grams of a surfactant.

[0073] The oil sludge is selected from an area with a particle size of 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 laurylaminopropionate 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 was weighed; the stirring speed was set to 500 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 50° C., the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 5 minutes, and the mass of each sulfonating agent added was 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 3 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 0.5 hours was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0076] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0077] (1) Channeling performance: The channeling 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system was measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent was diluted to a 3.0 wt% solution, which was injected into a capillary tube using a syringe. Then, a microinjector was used to inject an oil droplet (from the crude oil produced in the reservoir where the sludge used in this test was located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface finally stabilized at 0.053 mN / m.

[0079] Example 7

[0080] This 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 a sulfonating agent; 50 grams of an alkali neutralizing agent; and 30 grams of a surfactant.

[0081] The oil sludge is selected from an 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 was weighed; the stirring speed was set to 1000 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 50° C., the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 5 minutes, and the mass of each sulfonating agent added was 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 3 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 0.5 hours was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0084] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0085] (1) Channeling performance: The channeling 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 a 2PV 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system was measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent was diluted to a 3.0 wt% solution, which was injected into a capillary tube using a syringe. Then, a microinjector was used to inject an oil droplet (from the crude oil produced in the reservoir where the sludge used in this test was located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface finally stabilized at 0.041 mN / m.

[0087] Example 8

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

[0089] The oil sludge is selected from an area with a particle size of less than 60 μm, an oil content of 18%, and a viscosity of 1000 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 sodium laurylaminopropionate + 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 was weighed; the stirring speed was set to 500 rpm, and the sludge was added to the reactor under stirring. When the temperature in the reactor reached 50° C., the sulfonating agent was added, and the time interval between two adjacent additions of the sulfonating agent was controlled to be 5 minutes, and the mass of each sulfonating agent added was 5% of the total mass of the sulfonating agent. After the addition of the sulfonating agent was completed and the first set stirring time of 3 hours was reached, the alkali neutralizing agent was continued to be added to the reactor. After the second set stirring time of 0.5 hours was reached, a surfactant was added to the reactor, mixed, and naturally cooled to obtain the sludge displacement agent.

[0092] The flooding performance of a sludge flooding agent provided in this embodiment was tested, and the testing process is as follows:

[0093] (1) Channeling performance: The channeling 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 2PV 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 method for determining the performance of petroleum sulfonates for oil displacement. The interfacial tension of the oil-water phase in the sludge displacement agent system was measured using a CNG-701 rotating drop tensiometer. First, the sludge displacement agent was diluted to a 3.0 wt% solution, which was injected into a capillary tube using a syringe. Then, a microinjector was used to inject an oil droplet (from the crude oil produced in the reservoir where the sludge used in this test was located) into the external phase of the sludge displacement agent to complete the preparation of the capillary sample tube. Under simulated formation temperature conditions of 50°C, the oil-water interface finally stabilized at 0.071 mN / m.

[0095] (3) Enhanced oil recovery test: Three sand-filled pipes were connected in parallel, sharing the same injection port and outlet port. The permeabilities of the three pipes were 251 mD, 350 mD, and 1280 mD, respectively. The three pipes were saturated with crude oil (from the oil layer containing the test sludge). The volume of crude oil saturated in the pipes, V1, was recorded as 122 mL. Tap water was injected from the injection port at a rate of 5 mL / min until the output fluid at the outlet had a water content of 98%. A 2-volume injection of a 30% wt sludge displacement agent aqueous solution (prepared with tap water) was then started. Water flooding was then resumed until the output fluid at the outlet had a water content of 98%, and the test was terminated. The volume of crude oil collected from the outlet, V2, was 39 mL. The recovery factor was calculated as (V2 / V1) × 100%, and the experimental recovery factor 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 performance tests of Comparative Examples 1 to 3 were performed in the same manner as in 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 with those of Example 8 and Comparative Examples 1-3, we can see that Example 8 and Comparative Example 3, which rely on oil sludge and the residue after sludge sulfonation to plug high-permeability zones, have significantly higher plugging rates than Comparative Examples 1 and 2, which rely solely on oil sludge. Due to the synergistic effect of the petroleum sulfonate generated by the sulfonation of the oil sludge itself and the compounded surfactant, Example 8 exhibits stronger oil-washing capabilities, as evidenced by the ultra-low oil-water interfacial tension, compared to Comparative Example 2, which only uses the compounded surfactant, and Comparative Example 3, which only uses the petroleum sulfonate generated by the sulfonation of the oil sludge itself.

[0107] Furthermore, the oil recovery factor is positively correlated with the swept volume and oil-washing capacity of the displacement fluid, which in turn is positively correlated with the plugging efficiency. Furthermore, the recovery factor of Example 8 is significantly superior to that of the control group. Therefore, based on these combined effects, the inventors predict that, at the same usage rate and under the same reservoir conditions, the oil recovery factor can be increased by at least 5 percentage points.

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

[0109] Although specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications and substitutions may be made to those details in light of all the teachings disclosed herein, and such modifications are within the scope of the present invention. The full scope of the present invention is given by the appended claims and any equivalents thereof.

Claims

1. An oil sludge displacement agent, characterized in that: The preparation method of the oil sludge displacement agent comprises the following steps: S1. Weigh 1-5 parts of oil sludge, 1-5 parts of sulfonating agent, 0.1-5 parts of alkali neutralizing agent, and 0.01-3 parts of surfactant by mass; raise the temperature of the oil sludge while stirring, and then add the sulfonating agent to obtain a crude sulfonated oil 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 oil sludge displacement agent.

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 10-30%.

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 an oil sludge displacement agent, characterized in that: The following steps are involved: S1. Weigh 1-5 parts of oil sludge, 1-5 parts of sulfonating agent, 0.1-5 parts of alkali neutralizing agent, and 0.01-3 parts of surfactant by mass; raise the temperature of the oil sludge while stirring, and then add the sulfonating agent to obtain a crude sulfonated oil 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 oil 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 stirring 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 0.5-1 h, and the speed is 500-1000 rpm.

15. Use of the oil sludge control and displacement agent according to any one of claims 1 to 8 or the oil sludge control and displacement agent prepared by the method according to any one of claims 9 to 14 in performing profile control and displacement control in a petroleum production layer with water injection channeling.