Temperature-resistant anti-swelling agent for thermal recovery of offshore oilfield thickened oil and preparation method of temperature-resistant anti-swelling agent

Abstract

The invention discloses a temperature-resistant anti-swelling agent for thermal recovery of offshore oilfield thickened oil and a preparation method of the temperature-resistant anti-swelling agent. The temperature-resistant anti-swelling agent comprises the following components in percentage by mass: 15%-25% of a micromolecular cationic functional single agent, 10%-15% of a macromolecular cationic functional single agent, 1.0%-1.5% of a surface modifier, 10%-15% of an auxiliary agent and the balance of water. The temperature-resistant anti-swelling agent disclosed by the invention can tolerate a use environment of 300 DEG C, tolerates oil reservoir produced water with the total mineralization degree of less than or equal to 20000 mg / L, does not damage a stratum, and protects the environment. When a high-temperature anti-swelling agent working solution with the concentration of 4% is used for aging for 24 hours at the temperature of 300 DEG C, the anti-swelling rate exceeds 90%, and the washing resistance exceeds 90%.

Description

Technical Field

[0001] The invention relates to the technical field of heavy oil thermal recovery chemical enhancement, in particular to a temperature-resistant anti-swelling agent for heavy oil thermal recovery in offshore oil fields and a preparation method thereof. Background Art

[0002] During the heavy oil thermal recovery process, due to the complex reservoir sensitivity conditions, low steam condensate mineralization, high pH and other reasons, there are illite, montmorillonite and other easily swellable clays in the formation clay. The contact with steam condensate causes clay expansion, which affects the reservoir seepage channel, resulting in an increase in injection pressure at the beginning of heat and mass injection or during the development process, which in turn affects the injection capacity, making the steam injection rate unable to meet the process design requirements, causing heat loss, reducing steam thermal efficiency, and seriously affecting the development effect of steam throughput. At present, onshore oil fields widely use clay stabilizers to protect reservoirs in steam injection thermal recovery wells, and have achieved good application results. Offshore heavy oil thermal recovery is in its infancy, and steam throughput test wells use high-temperature anti-swelling systems to protect reservoirs. With the continuous increase in thermal recovery planning production and the successive commissioning of new oil fields, the demand for thermal recovery clay stabilizers has increased significantly. At the same time, complex reservoir conditions and multiple development methods have put forward diverse demands on clay stabilizer systems.

[0003] The existing clay stabilizers in oil fields mainly include inorganic salt (such as potassium chloride) type clay stabilizers and polymer anti-swelling agents such as polyamines and polyquaternary ammonium. Inorganic salt clay stabilizers are easy to obtain, cheap, and simple to maintain, but they have poor timeliness, large dosage, and are not resistant to water washing; polymer anti-swelling agents such as polyamines and polyquaternary ammonium have good anti-swelling effects in hydrochloric acid systems and small dosages, but their thermal stability is poor, and their temperature resistance decreases with the increase of relative molecular mass. They are not suitable for clay anti-swelling under high temperature conditions. At the same time, with the development of medium and low permeability oil reservoirs, polymer-type high-molecular anti-swelling agents are easy to adsorb and block pores due to their long molecular chains, resulting in a decrease in reservoir permeability and increasing the difficulty of later water injection development. At present, there are no related reports on the use of temperature-resistant anti-swelling agents suitable for heavy oil thermal treatment in offshore oil fields. Summary of the invention

[0004] In order to solve the problem of reduced permeability caused by reservoir clay expansion during heavy oil steam injection production, the present invention provides a heat-resistant anti-swelling agent for heavy oil heat use in offshore oil fields and a preparation method thereof. The anti-swelling agent of the present invention can withstand a 300°C temperature environment, can withstand oil reservoir produced water with a total mineralization of less than or equal to 20,000 mg / L, and does not damage the formation, thus protecting the environment. Using a 4% concentration of high-temperature anti-swelling agent working fluid, aged at 300°C for 24 hours, the anti-swelling rate exceeds 90%, and the water washability exceeds 90%.

[0005] In a first aspect, the present invention provides a heat-resistant anti-swelling agent for heavy oil in offshore oil fields, which is achieved by adopting the following technical solution.

[0006] A heat-resistant anti-swelling agent for heavy oil in offshore oil fields comprises the following components in percentage by mass: 15-25% of a small molecule cationic functional single agent, 10-15% of a high molecule cationic functional single agent, 1.0-1.5% of a surface modifier, 10-15% of an auxiliary agent, and the balance is water.

[0007] Furthermore, the small molecule cationic functional single agent is selected from at least one of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CAS No.: 3327-22-8), 2-chloroethyltrimethylammonium chloride (CAS No.: 999-81-5), and 3-chloropropyltrimethylammonium chloride (CAS No.: 1936-95-4).

[0008] Furthermore, the polymer cationic functional single agent is selected from at least one of polyquaternium-39 (CAS No.: 25136-75-8), polyquaternium-47 (CAS No.: 197969-51-0), and polydimethyldiallylammonium chloride (CAS No.: 26062-79-3).

[0009] Furthermore, the surface modifier is selected from at least one of dodecylbenzyltrimethylammonium chloride (CAS No.: 1330-85-4), tetradecyltrimethylammonium chloride (CAS No.: 4574-04-3), hexadecyldimethylbenzylammonium chloride (CAS No.: 122-18-9), and octadecyldimethylbenzylammonium chloride (CAS No.: 122-19-0).

[0010] Furthermore, the auxiliary agent is selected from at least one of sodium chloride, sodium bromide, potassium chloride and ammonium chloride.

[0011] In a second aspect, the present invention provides a method for preparing a heat-resistant anti-swelling agent for heavy oil in offshore oil fields, which is achieved by adopting the following technical scheme.

[0012] A method for preparing the above-mentioned offshore oilfield heavy oil thermal use temperature resistant anti-swelling agent comprises the following steps:

[0013] At room temperature and pressure, first mix the specified amount of additives and water, stir thoroughly until dissolved, then add the specified amount of small molecule cationic functional single agent, polymer cationic functional single agent, and surface modifier in sequence, control the temperature at 50-70°C, stir until a uniform single-phase liquid is obtained, and a temperature-resistant anti-swelling agent is obtained.

[0014] The present invention achieves the following beneficial effects.

[0015] In view of the characteristics of offshore oilfield heavy oil thermal recovery and steam injection development, the present invention selects a low molecular cationic anti-swelling agent as the main agent in the single agent formulation, supplemented by a high molecular anti-swelling agent and an auxiliary agent to form a temperature-resistant anti-swelling agent, which can adapt to the harsh application environment of heavy oil thermal recovery. In addition, the added surface modifier improves the wetting reversal function, achieving multiple functions of one agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a microscopic picture of the clay before and after adding the anti-swelling agent of Example 2 of the present invention (wherein the left picture is the initial clay, and the right picture is the clay after the anti-swelling agent is added). DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below through specific implementation methods.

[0018] Example 1

[0019] The heat-resistant anti-swelling agent is calculated by mass percentage, and its system components include: 21% of small molecule cationic functional single agent (2-chloroethyltrimethylammonium chloride), 13% of high molecular cationic functional single agent (polyquaternium salt-39), 1.0% of surface modifier (octadecyl dimethyl benzyl ammonium chloride), 15% of auxiliary agent (potassium chloride), and the rest is water.

[0020] Preparation method: At room temperature and pressure, first add the additive and water into the compounding kettle, stir thoroughly until dissolved, then add the small molecule cationic functional single agent, the polymer cationic functional single agent, and the surface modifier into the compounding kettle in sequence, control the temperature at 70°C, stir until a uniform single-phase liquid is obtained to obtain the above product.

[0021] The product obtained in Example 1 was prepared into a concentration of 4% for performance testing, and the test conditions were as follows:

[0022] 1. Testing instruments: centrifuge, high temperature displacement device, etc.;

[0023] 2. Experimental temperature: room temperature, 300°C;

[0024] 3. Experimental materials: artificial sandfill, core of an offshore oil field (permeability 2000mD), distilled water, etc.

[0025] The experimental results are shown in the following table:

[0026]

[0027] Note: The three tests of anti-swelling rate, water washability and permeability retention rate are based on Q / SH10201966-2013 General Technical Conditions for High Temperature Clay Stabilizers

[0028] Example 2

[0029] The heat-resistant anti-swelling agent is calculated by mass percentage, and its system components include: 17% of small molecule cationic functional single agent (3-chloropropyltrimethylammonium chloride), 10% of high molecular cationic functional single agent (polyquaternium salt-47), 1.5% of surface modifier (dodecylbenzyltrimethylammonium chloride), 10% of auxiliary agent (ammonium chloride), and the rest is water.

[0030] Preparation method: At room temperature and pressure, add small molecule cationic functional single agent, polymer cationic functional single agent, surface modifier, additive and water into the compounding kettle in sequence, control the temperature at 70°C, stir until a uniform single-phase liquid is obtained to obtain the above product.

[0031] The product obtained in Example 2 was prepared into a concentration of 2% for performance testing, and the test conditions were as follows:

[0032] 1. Testing instruments: centrifuge, high temperature displacement device, etc.;

[0033] 2. Experimental temperature: room temperature, 250℃;

[0034] 3. Experimental materials: artificial sandfill, core of an offshore oil field (permeability 3500mD), distilled water, etc.

[0035] The experimental results are shown in the following table:

[0036]

[0037] The heat-resistant anti-swelling agent of the present invention can withstand a 300°C use environment, withstand oil reservoir produced water with a total mineralization of less than or equal to 20,000 mg / L and a total calcium and magnesium ion concentration of less than or equal to 2,000 mg / L, and does not damage the formation, thus protecting the environment. Using a 4% high-temperature anti-swelling agent working fluid, after aging for 24 hours at 300°C, the anti-swelling rate exceeds 90%, and the water wash resistance rate exceeds 90%. All performance indicators are superior to commercial anti-swelling agent A.

[0038] This application observes the microscopic state of clay before and after the addition of the anti-swelling agent, such as Figure 1 As shown, the initial clay is in a dispersed particle state, and the clay particles treated with the clay stabilizer are distributed in multiple layers and aggregated into large, dispersed blocks, indicating that the anti-swelling agent still has a good effect on the surface of the clay particles.

[0039] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering technicians in the field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have been fully recorded in the technical requirements.

Claims

1. A heat-resistant anti-swelling agent for heavy oil in offshore oil fields, characterized in that: The invention comprises the following components in percentage by mass: 15-25% of a small molecule cationic functional single agent, 10-15% of a high molecule cationic functional single agent, 1.0-1.5% of a surface modifier, 10-15% of an auxiliary agent, and the balance is water.

2. The heat-resistant anti-swelling agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The small molecule cationic functional single agent is selected from at least one of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 2-chloroethyltrimethylammonium chloride, and 3-chloropropyltrimethylammonium chloride.

3. The heat-resistant anti-swelling agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The polymer cationic functional single agent is selected from at least one of polyquaternium-39, polyquaternium-47, and polydimethyldiallylammonium chloride.

4. The heat-resistant anti-swelling agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The surface modifier is at least one selected from dodecylbenzyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyldimethylbenzylammonium chloride, and octadecyldimethylbenzylammonium chloride.

5. The heat-resistant anti-swelling agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The auxiliary agent is selected from at least one of sodium chloride, sodium bromide, potassium chloride and ammonium chloride.

6. A method for preparing the offshore oilfield heavy oil thermal use temperature resistant anti-swelling agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: At room temperature and pressure, first mix the specified amount of additives and water, stir thoroughly until dissolved, then add the specified amount of small molecule cationic functional single agent, polymer cationic functional single agent, and surface modifier in sequence, control the temperature at 50-70°C, stir until a uniform single-phase liquid is obtained, and a temperature-resistant anti-swelling agent is obtained.

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