Temperature-resistant and salt-resistant flooding and washing agent for offshore oilfield thickened oil thermal recovery and preparation method thereof

Abstract

The invention discloses a temperature-resistant and salt-resistant flooding and washing agent for thermal recovery of offshore oilfield thickened oil and a preparation method thereof, and belongs to the technical field of chemical synergism of thermal recovery of thickened oil. The temperature-resistant and salt-resistant flooding and washing agent comprises the following components in percentage by mass: 10-15% of a nonionic surfactant, 10-15% of a zwitterionic surfactant, 1.5-3.0% of a special surfactant, 5-10% of a permeation aid and the balance of water. The water reducer can tolerate the operating environment of 250 DEG C, can tolerate oil reservoir produced water with the total mineralization degree smaller than or equal to 20000 mg / L (the sum of the concentrations of calcium and magnesium ions is smaller than or equal to 2000 mg / L), does not damage the stratum, and protects the environment. After the working solution with the concentration of 1% is aged for 24 h at the temperature of 250 DEG C, the interfacial tension can reach 10 <-3 > level through a test after the working solution is mixed with crude oil, and the oil displacement efficiency is improved by more than 8% compared with that of steam displacement.

Description

Technical Field

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

[0002] In the middle and late stages of heavy oil thermal recovery steam and hot water huff and puff production in offshore oil fields, there will be problems with low residual oil content and low oil washing efficiency within the thermal mass sweep range. The main reason is that the colloid and asphaltene components of heavy oil account for a high proportion, the viscosity is large, and the properties and structures of steam or hot water are quite different, so it is impossible to form a miscible fluid with them. In addition, sampling and analysis of the produced fluid found that the viscosity of the produced fluid increased significantly, which was caused by the formation of oil-in-water emulsion. Through investigation and analysis, similar problems of low oil washing efficiency also occur in onshore heavy oil thermal recovery oil fields, resulting in a decrease in heavy oil thermal recovery production, which seriously affects the effect of heavy oil thermal recovery development. The phenomenon of low oil washing efficiency within the sweep range of steam / hot water is relatively common in offshore oil fields, and the market potential is huge. The method of using temperature-resistant and salt-resistant flooding agents to improve the oil washing efficiency in the near-wellbore zone has the advantages of low cost, low process difficulty, and quick results, providing technical support for the efficient development of heavy oil.

[0003] High-temperature oil displacement agents in thermal recovery of heavy oil is a key research field, which aims to improve the efficiency of heavy oil recovery and reduce production costs. The current research status mainly focuses on the optimization of high-temperature heavy oil displacement agent formula, the research of high-temperature performance improvers and the research of environmentally friendly oil displacement agents. Through experiments, researchers have continuously optimized the formula of high-temperature heavy oil displacement agents, including the proportion and type of ingredients such as thickeners, surfactants, and penetration aids, in order to improve oil recovery efficiency and adapt to high-temperature environments. With the improvement of environmental awareness, researchers are also exploring the development of environmentally friendly high-temperature heavy oil displacement agents to reduce the impact on the environment and improve the sustainability of production. However, there are currently no reports on temperature-resistant and salt-resistant displacement agents suitable for thermal recovery of heavy oil in offshore oil fields. Summary of the invention

[0004] In order to solve the problem of low oil washing efficiency in the production process of heavy oil injection steam / hot water, the present invention provides a heat-resistant and salt-resistant washing agent for heavy oil in offshore oil fields and a preparation method thereof.

[0005] In a first aspect, the present invention provides a heat-resistant and salt-resistant flooding agent for heavy oil thermal use in offshore oil fields, which is achieved by adopting the following technical solutions.

[0006] A heat-resistant and salt-resistant washing agent for heavy oil in offshore oil fields comprises the following components in percentage by mass: 10-15% of nonionic surfactant, 10-15% of zwitterionic surfactant, 1.5-3.0% of special surfactant, 5-10% of penetration aid, and the balance is water.

[0007] Furthermore, the nonionic surfactant is selected from C 12-18 Fatty alcohol polyoxyethylene (10) ether, C 12-18 Fatty alcohol polyoxyethylene (15) ether, C 12-18 Fatty alcohol polyoxyethylene (20) ether, C 12-18 At least one of fatty alcohol polyoxyethylene (25) ethers.

[0008] Furthermore, the zwitterionic surfactant is selected from at least one of dodecyl dimethyl betaine (CAS No.: 683-10-3), tetradecyl dimethyl betaine (CAS No.: 2601-33-4), cocamidopropyl hydroxysulfonyl betaine (CAS No.: 68139-30-0), and erucamidopropyl hydroxysulfonyl betaine (CAS No.: 581089-19-2).

[0009] Furthermore, the special surfactant is selected from at least one of sodium perfluorododecyl sulfonate (CAS No.: 1260224-54-1), ammonium perfluorooctane sulfonate (CAS No.: 29081-56-9), and perfluorooctylethanol polyoxyethylene ether (purchased from Shandong Xingang Chemical Co., Ltd.).

[0010] Furthermore, the penetration aid is selected from at least one of polyethylene glycol, polypropylene glycol, and ethylene glycol.

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

[0012] A preparation method of the above-mentioned offshore oilfield heavy oil hot-adopting temperature-resistant and salt-resistant flooding agent comprises the following steps: at normal temperature and pressure, firstly mixing a penetration aid and water, stirring fully until dissolved, then sequentially adding a nonionic surfactant, a zwitterionic surfactant and a special surfactant, controlling the temperature at 40-60°C, stirring until a uniform single-phase liquid is obtained to obtain a flooding agent product.

[0013] This application has the following beneficial effects.

[0014] Aiming at the characteristics of heavy oil thermal recovery and steam injection development in offshore oil fields, the present invention adopts non-ionic and zwitterionic surfactants as the main agents in the selection of single-agent formulas, supplemented with special surfactants to improve the temperature resistance of the system, and penetration aids to increase the permeability of the system to prepare a heat-resistant and salt-resistant flooding agent that can adapt to the harsh application environment of heavy oil thermal recovery. The present invention can withstand an operating environment of 250°C, and can withstand oil reservoir produced water with a total mineralization of less than or equal to 20,000 mg / L (the sum of calcium and magnesium ion concentrations is less than or equal to 2,000 mg / L), and does not damage the formation, thus protecting the environment. Using a 1% concentration working fluid, after aging at 250°C for 24 hours, the interfacial tension tested when mixed with crude oil can reach 10-3 The oil recovery efficiency is increased by more than 8% compared with steam drive. DETAILED DESCRIPTION

[0015] The present patent application is further described below in conjunction with embodiments.

[0016] Unless otherwise specified, the experimental methods used in the following preparation examples and examples are all conventional methods; the materials, reagents, etc. used in the following preparation examples and examples are all commercially available unless otherwise specified.

[0017] The C used in this embodiment 12-18 Fatty alcohol polyoxyethylene (10) ether, C 12-18 Fatty alcohol polyoxyethylene (15) ether, C 12-18 Fatty alcohol polyoxyethylene (20) ether, C 12-18 Fatty alcohol polyoxyethylene (25) ether was purchased from China Light Industry Co., Ltd.

[0018] Example 1

[0019] A heat-resistant and salt-resistant washing agent for heavy oil in offshore oil fields, wherein the system components include, by mass percentage, 11% of a nonionic surfactant (C 12-18 Fatty alcohol polyoxyethylene (15) ether), 13% zwitterionic surfactant (tetradecyl dimethyl betaine), 1.5% special surfactant (sodium perfluorododecyl sulfonate), 8% penetration aid (polyethylene glycol), and the rest is water.

[0020] Preparation method: At room temperature and pressure, first add the penetration aid and water into the compounding kettle, stir thoroughly until dissolved, then add the nonionic surfactant, zwitterionic surfactant and special surfactant into the compounding kettle in turn, control the temperature at 55°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 1% for performance testing. The test standard was based on "QSH10202191-2018 Technical Requirements for Surfactants for Oil Displacement". The test conditions were:

[0022] 1. Testing instruments: rotating drop interfacial tension meter, high temperature displacement device, etc.

[0023] 2. Experimental temperature: 50℃, 250℃;

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

[0025] Ion composition of formation water in an oil field

[0026]

[0027] The experimental results are shown in the following table:

[0028]

[0029]

[0030] Example 2

[0031] A heat-resistant and salt-resistant washing agent for heavy oil in offshore oil fields, wherein the system components include, by mass percentage, 13% of a nonionic surfactant (C 12-18 Fatty alcohol polyoxyethylene (10) ether), 11% of zwitterionic surfactant (dodecyl dimethyl betaine), 2.0% of special surfactant (sodium perfluorododecyl sulfonate), 6.5% of penetration aid (ethylene glycol), and the rest is water.

[0032] Preparation method: first put the single-dose raw material into a warm pool to increase the temperature to increase fluidity, use a pharmaceutical pump to add the penetration aid and water to the compounding kettle, stir thoroughly until dissolved, then add the non-ionic surfactant, zwitterionic surfactant and special surfactant to the compounding kettle in turn, control the temperature at 50°C, stir until a uniform single-phase liquid is obtained to obtain the above product.

[0033] The winter environment formula product obtained in Example 2 was prepared into a concentration of 1.5% for performance testing. The test standard was based on "QSH10202191-2018 Technical Requirements for Surfactants for Oil Displacement". The test conditions were:

[0034] 1. Testing instruments: rotating drop interfacial tension meter, high temperature displacement device, etc.

[0035] 2. Experimental temperature: 50℃, 200℃;

[0036] 3. Experimental materials: artificial sandfill, core of an offshore oil field (permeability 3500mD), distilled water, etc.

[0037] The experimental results are shown in the following table:

[0038]

[0039]

[0040] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat-resistant and salt-resistant flooding agent for heavy oil in offshore oil fields, characterized in that: The invention comprises the following components in percentage by mass: 10-15% of nonionic surfactant, 10-15% of zwitterionic surfactant, 1.5-3.0% of special surfactant, 5-10% of penetration aid, and the balance is water.

2. The heat-resistant and salt-resistant flooding agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The nonionic surfactant is selected from C 12-18 Fatty alcohol polyoxyethylene (10) ether, C 12-18 Fatty alcohol polyoxyethylene (15) ether, C 12-18 Fatty alcohol polyoxyethylene (20) ether, C 12-18 At least one of fatty alcohol polyoxyethylene (25) ethers.

3. The heat-resistant and salt-resistant flooding agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The zwitterionic surfactant is selected from at least one of dodecyl dimethyl betaine, tetradecyl dimethyl betaine, cocamidopropyl hydroxysulfonyl betaine and erucamidopropyl hydroxysulfonyl betaine.

4. The heat-resistant and salt-resistant flooding agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The special surfactant is selected from at least one of sodium perfluorododecyl sulfonate, ammonium perfluorooctane sulfonate, and perfluorooctylethanol polyoxyethylene ether.

5. The heat-resistant and salt-resistant flooding agent for heavy oil in offshore oil fields according to claim 1, characterized in that: The penetration aid is selected from at least one of polyethylene glycol, polypropylene glycol and ethylene glycol.

6. A method for preparing a heat-resistant and salt-resistant flooding agent for heavy oil in offshore oil fields 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 penetration aid and water, stir thoroughly until dissolved, then add nonionic surfactant, zwitterionic surfactant and special surfactant in sequence, control the temperature at 40-60°C, stir until a uniform single-phase liquid is obtained to obtain a repellent product.

Images