Micro-emulsion type heavy oil cold production oil-displacing agent with pH response characteristic, preparation method and application of micro-emulsion type heavy oil cold production oil-displacing agent

Abstract

The invention relates to a microemulsion type heavy oil cold production oil-displacing agent with a pH response characteristic. The problems that the emulsification efficiency is low due to insufficient shear energy of the existing oil-displacing agent in the stratum migration process, and the effects of reducing the viscosity of heavy oil and improving the recovery ratio cannot be met are mainly solved. The invention relates to an oil phase emulsion which is characterized by comprising the following components in parts by weight: 20-40 parts of an oil phase, 8-20 parts of an emulsifier, 22-60 parts of water and 0.5-2 parts of alkali. The preparation method comprises the following steps: proportionally mixing the components according to the sequence of the oil phase, the emulsifier, the water and the alkali, and stirring until a homogeneous microemulsion is obtained, namely the microemulsion type heavy oil cold production oil displacement agent with the pH response characteristic. According to the microemulsion type heavy oil cold production oil-displacing agent with the pH response characteristic, the emulsification viscosity reduction efficiency of heavy oil can be improved, and the recovery efficiency is further improved.

Description

Technical field:

[0001] The invention relates to the technical field of oil recovery chemistry in oil and gas field development, and in particular to a microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics, a preparation method and application thereof. Background technology:

[0002] my country is rich in heavy oil resources and has huge resource potential. However, heavy oil has high viscosity and is difficult to develop. Thermal recovery methods such as steam stimulation, steam flooding, and burning oil layers have problems such as high energy consumption and high heat loss rate, which restrict the sustainable and stable development of heavy oil development. In recent years, the development method of heavy oil has gradually changed from thermal recovery to cold recovery, that is, by injecting cold recovery oil displacement agents into the formation, the viscosity of heavy oil is reduced while the fluidity of crude oil is improved to achieve the purpose of increasing the recovery rate of heavy oil. Commonly used heavy oil cold recovery oil displacement agents mainly include surfactants, active polymers, nanomaterials, etc., which form low-viscosity water-in-oil (O / W) emulsions with good fluidity through emulsification to reduce the viscosity of heavy oil and improve the recovery rate. However, the viscosity of heavy oil is high, and the shear energy of the oil displacement agent during the migration of the formation is insufficient, resulting in low emulsification efficiency, which cannot meet the effect of reducing the viscosity of heavy oil and improving the recovery rate. Therefore, how to improve the emulsification and viscosity reduction efficiency of heavy oil and further improve the recovery rate is of great significance for the cold recovery of heavy oil. Summary of the invention:

[0003] The purpose of the present invention is to overcome the problem that the existing oil displacement agent in the background technology has insufficient shear energy during the migration process in the formation, resulting in low emulsification efficiency and unable to meet the effect of reducing the viscosity of heavy oil and improving the recovery rate, and to provide a microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics. The microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics can improve the emulsification viscosity reduction efficiency of heavy oil and further improve the recovery rate. The present invention also provides a preparation method and application of a microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics.

[0004] In order to achieve the above object, the first aspect of the present invention provides a microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics, which comprises the following components by weight: 20-40 parts of oil phase, 8-20 parts of emulsifier, 22-60 parts of water, and 0.5-2 parts of alkali.

[0005] Preferably, the oil phase is any one of kerosene, diesel, alkane, olefin, and aromatic hydrocarbon.

[0006] Preferably, the emulsifier is a combination of a nonionic surfactant and an anionic surfactant; the molar ratio of the nonionic surfactant to the anionic surfactant is 1:1.1.

[0007] Preferably, the nonionic surfactant is any one of lauryl glucoside, sorbitan fatty acid ester, polyoxyethylene octylphenol ether-10, sorbitan monooleate polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

[0008] Preferably, the anionic surfactant is spontaneously formed from aromatic aldehyde and primary amine in an alkaline environment; the molar ratio of the primary amine to the aromatic aldehyde is 1:1.2.

[0009] Preferably, the aromatic aldehyde is p-hydroxybenzaldehyde or p-carboxybenzaldehyde; the primary amine is n-hexylamine or n-octylamine; and the base includes any one of sodium hydroxide, potassium hydroxide and sodium carbonate.

[0010] Another aspect of the present invention provides a method for preparing a microemulsion type heavy oil cold recovery displacement agent having pH response characteristics, comprising the following steps:

[0011] The above components are mixed in the order of oil phase, emulsifier, water and alkali according to the proportion, and stirred until a homogeneous microemulsion is obtained, which is the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics of the present invention.

[0012] The stirring speed of the homogeneous microemulsion is 50-200 r / min and the stirring time is 5-30 min.

[0013] A third aspect of the present invention provides a use of a microemulsion type heavy oil cold recovery displacement agent with pH response characteristics in heavy oil production.

[0014] The specific application method is: in the actual heavy oil production process, the prepared microemulsion type heavy oil cold recovery oil displacement agent is diluted 1-100 times with injection water, injected into the ground in the form of small plugs, and cooperated with subsequent water drive for efficient heavy oil production.

[0015] The microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics uses a viscosity reducing solvent with dilution viscosity reducing effect as the oil phase and a solution containing an emulsifier as the water phase to construct a microemulsion. The viscosity reducing solvent in the microemulsion reduces the viscosity by dissolving the colloid and asphaltene in the heavy oil and breaking up the aggregate structure in the heavy oil. The heavy oil after viscosity reduction is further reduced in viscosity and the fluidity of the crude oil is enhanced by the emulsification effect of the emulsifier. Under the dual viscosity reduction effect, the recovery rate of heavy oil is greatly improved. At the same time, in order to avoid the problem of high emulsion stability in the produced fluid, dynamic chemical bonds are introduced in the design of the molecular structure of the emulsifier, and the pH response characteristics of the dynamic chemical bonds are used to achieve flexible regulation of the stable / instability state of the emulsion.

[0016] Compared with the above background technology, the present invention has the following beneficial effects:

[0017] 1. The microemulsion type heavy oil cold recovery displacement agent with pH response characteristics of the present invention has the dual effects of dilution viscosity reduction and emulsification viscosity reduction, can greatly improve the heavy oil recovery rate without heating conditions, and has broad application prospects.

[0018] 2. The emulsifier involved in the present invention includes an anionic surfactant based on dynamic chemical bonds, which can be spontaneously generated in an alkaline environment, and the surfactant molecules spontaneously break in an acidic environment. The flexible pH controllability can effectively solve the problems of high stability of the produced fluid and difficulty in demulsification.

[0019] 3. The preparation method of the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics of the present invention is simple, avoiding a complicated synthesis process, and is conducive to practical application on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] Attached Figure 1 This is the macroscopic morphology and particle size distribution diagram of the pH-responsive microemulsion type heavy oil cold recovery displacement agent of the present invention;

[0022] Attached Figure 2 This is the process of emulsifying and reducing the viscosity of heavy oil by the pH-responsive microemulsion type heavy oil cold recovery displacement agent of the present invention;

[0023] Attached Figure 3 It is the dynamic production curve of the core displacement process of the pH-responsive microemulsion type heavy oil cold recovery displacement agent of the present invention. Specific implementation method:

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0025] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0026] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0027] The present invention provides a microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics, which comprises the following components by weight: 20-40 parts of oil phase, 8-20 parts of emulsifier, 22-60 parts of water, and 0.5-2 parts of alkali;

[0028] The oil phase is kerosene, diesel, alkane, olefin or aromatic hydrocarbon.

[0029] The emulsifier is a combination of a nonionic surfactant and an anionic surfactant; the ratio of the nonionic surfactant to the anionic surfactant is 1:1.1.

[0030] The nonionic surfactant is any one of lauryl glucoside, sorbitan fatty acid ester, polyoxyethylene octylphenol ether-10, sorbitan monooleate polyoxyethylene ether, and fatty alcohol polyoxyethylene ether; the anionic surfactant is spontaneously formed by aromatic aldehyde and primary amine in an alkaline environment; the ratio of primary amine to aromatic aldehyde is 1:1.2; the aromatic aldehyde is p-hydroxybenzaldehyde or p-carboxybenzaldehyde; the primary amine is n-hexylamine or n-octylamine; and the alkali includes sodium hydroxide, potassium hydroxide or sodium carbonate.

[0031] Taking the anionic pH-responsive surfactant formed by p-hydroxybenzaldehyde and n-hexylamine as an example, its formation process is as follows:

[0032]

[0033] Another aspect of the present invention provides a method for preparing a microemulsion type heavy oil cold recovery displacement agent with pH response characteristics, comprising the following steps:

[0034] The above components are mixed in the order of oil phase, emulsifier, water and alkali according to the proportion, and the stirring speed is 50-200r / min; the stirring time is 5-30min, until a homogeneous microemulsion is obtained, which is the microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics of the present invention.

[0035] The present invention also provides a microemulsion type heavy oil cold recovery oil displacement agent with pH response characteristics and its application in heavy oil recovery.

[0036] The specific application method is: in the actual heavy oil production process, the prepared microemulsion type heavy oil cold recovery oil displacement agent is diluted 1-100 times with injection water, injected into the ground in the form of small plugs, and cooperated with subsequent water drive for efficient heavy oil production.

[0037] Embodiment 1:

[0038] Take 32 parts of kerosene, 50 parts of water, 8 parts of lauryl glucoside, 4.8 parts of p-hydroxybenzaldehyde, 4 parts of n-hexylamine, and 1.2 parts of sodium hydroxide, mix the above components, and stir at a speed of 100 r / min for 5 minutes until the mixture is uniformly stirred to obtain a microemulsion type heavy oil cold recovery flooding agent with pH response characteristics.

[0039] The performance test of the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics constructed in Example 1.

[0040] Test Example 1:

[0041] Taking the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics constructed in Example 1 as an example, its macroscopic morphology and particle size distribution curve are as follows: Figure 1 The obtained pH-responsive microemulsion type heavy oil cold recovery oil displacement agent has a uniform and transparent appearance, and the particle size median of the oil displacement agent measured by a particle size analyzer is about 10 nm, and has long-term stability.

[0042] Test Example 2:

[0043] Taking the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics constructed in Example 1 as an example, it was contacted with heavy oil to observe the emulsification and viscosity reduction process of the displacement agent and the heavy oil, and the generated emulsion droplets were observed using an optical microscope, as shown in FIG. Figure 2 shown.

[0044] Among them, the viscosity of heavy oil at 60°C is 14800 mPa·s. It can be found that due to the high viscosity and high density of heavy oil, the heavy oil is located at the bottom of the sample bottle ( Figure 2 a). After adding the oil displacement agent, as time goes by, the heavy oil gradually separates from the bottom in the form of small oil droplets, floats up, and finally gathers at the top ( Figure 2 b and Figure 2 c). When the heavy oil drops reach the top of the bottle, invert it three times. The oil displacement agent can completely emulsify the heavy oil and form a stable water-in-oil emulsion, which greatly reduces the viscosity of the heavy oil ( Figure 2 d).

[0045] Test Example 3:

[0046] Taking the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics constructed in Example 1 as an example, a core physical simulation displacement experiment was carried out in combination with reservoir conditions. The dynamic production curve is as follows: Figure 3 As shown. Figure 3 It can be seen that the injection volume of the oil displacement agent is 0.15PV and the injection rate is 0.1mL / min. The total recovery factor can reach 39.24%, and the recovery factor increase is 26.13%, which effectively improves the heavy oil recovery factor.

[0047] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to perform equivalent replacements on parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. Although the above describes the specific implementation methods of the present invention, it is not intended to limit the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

Claims

1. A microemulsion type heavy oil cold recovery displacement agent with pH response characteristics, characterized in that: Its weight parts The invention comprises the following components: 20-40 parts of oil phase, 8-20 parts of emulsifier, 22-60 parts of water and 0.5-2 parts of alkali.

2. The microemulsion type heavy oil cold recovery displacement agent with pH response characteristics according to claim 1, characterized in that: The oil phase is any one of kerosene, diesel, alkane, olefin and aromatic hydrocarbon.

3. The microemulsion type heavy oil cold recovery displacement agent with pH response characteristics according to claim 1, characterized in that: The emulsifier is a combination of a nonionic surfactant and an anionic surfactant; the molar ratio of the nonionic surfactant to the anionic surfactant is 1:1.

1.

4. The microemulsion type heavy oil cold recovery displacement agent with pH response characteristics according to claim 3, characterized in that: The nonionic surfactant is any one of lauryl glucoside, sorbitan fatty acid ester, polyoxyethylene octylphenol ether-10, sorbitan monooleate polyoxyethylene ether and fatty alcohol polyoxyethylene ether.

5. The microemulsion type heavy oil cold recovery displacement agent with pH response characteristics according to claim 3, characterized in that: The anionic surfactant is spontaneously formed by aromatic aldehyde and primary amine in an alkaline environment; the molar ratio of the primary amine to the aromatic aldehyde is 1:1.

2.

6. The microemulsion type heavy oil cold recovery displacement agent with pH response characteristics according to claim 5, characterized in that: The aromatic aldehyde is any one of p-hydroxybenzaldehyde and p-carboxybenzaldehyde; the primary amine is any one of n-hexylamine and n-octylamine; and the base includes any one of sodium hydroxide, potassium hydroxide and sodium carbonate.

7. A method for preparing a microemulsion type heavy oil cold recovery displacement agent with pH response characteristics according to any one of claims 1 to 6, characterized in that: The following steps are involved: The above components are mixed in the order of oil phase, emulsifier, water and alkali according to the proportion, and stirred until a homogeneous microemulsion is obtained, which is the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics of the present invention.

8. The preparation method according to claim 7, characterized in that: The stirring speed for obtaining a homogeneous microemulsion is 50-200 r / min; the stirring time is 5-30 min.

9. Use of the microemulsion type heavy oil cold recovery displacement agent with pH response characteristics according to any one of claims 1 to 6 in heavy oil production.

10. The use according to claim 9, characterized in that: The specific application method is: in the actual heavy oil production process, the prepared microemulsion type heavy oil cold recovery oil displacement agent is diluted 1-100 times with injection water, injected into the ground in the form of small plugs, and cooperated with subsequent water drive for efficient heavy oil production.

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