Oilfield wicking and washing oil microemulsion and preparation method thereof

Abstract

The present invention provides an oilfield imbibition oil washing microemulsion and a preparation method thereof. The raw materials of the microemulsion, calculated by weight as 100%, include 0.050%-0.075% of a dialkyl quaternary ammonium salt cationic surfactant, 0.226%-0.330% of a fatty amine polyoxyethylene ether, 0.035%-0.050% of a propylene glycol block polyether, and 0.025%-0.055% of a naphthalenesulfonate formaldehyde polymer, with the balance being water. The oilfield imbibition oil washing microemulsion of the present invention has an oil washing efficiency of greater than or equal to 67%, increases sandstone recovery by 8.4% compared to water flooding, and increases shale recovery by 14.5%, achieving significant imbibition oil recovery effects.

Description

Technical Field

[0001] The invention relates to the technical field of oil reservoir exploitation, in particular to an oilfield imbibition wash oil microemulsion and a preparation method thereof. Background Art

[0002] China is rich in shale oil resources. It is estimated that the country's technically recoverable shale oil resources are about 150*10 8 t, is to ensure the security of national oil supply and support crude oil 2*10 8 China's oil shale production has maintained rapid growth in the past 10 years, reaching 911 million tons in 2019. 5 t scale, with an average annual growth rate exceeding 12%. However, compared with North American marine shale oil, China's continental shale oil has a wide variety of lithofacies, strong heterogeneity, complex tectonic environments and geological characteristics, and low production capacity. Efficient exploration and development still face numerous challenges and difficulties. Shale and tight oil reservoirs are difficult to replenish energy, and effective displacement systems are difficult to establish. As a result, shale oil recovery rates are generally less than 10%. In light of the challenges and development needs of continental shale oil development, in order to achieve the goal of reducing costs and increasing efficiency, it is necessary to research shale oil recovery enhancement technologies to improve development effectiveness and efficiency.

[0003] Shale oil reservoirs exhibit strong imbibition, a phenomenon in which fluids in porous media spontaneously enter the pores of the porous medium due to capillary forces. This imbibition is particularly strong in shale oil reservoirs, contributing 24.5% to 31.1% of the total volume. The smaller the reservoir pores, the stronger the imbibition. Therefore, fully leveraging the capillary forces of shale reservoirs to further enhance spontaneous imbibition recovery, increase single-well production, and reduce overall production costs is of great significance.

[0004] Rock wettability and interfacial tension influence oil recovery efficiency. Statistical data from oilfield development practices show that reservoir surface properties significantly influence development outcomes. Recovery rates for oil-wet reservoirs are currently only around 45%, while those for water-wet reservoirs can reach 80%. Furthermore, altering capillary forces—that is, reducing interfacial tension—can significantly decrease residual oil saturation.

[0005] Peng Chong et al. reported in 2020 that the interfacial tension between the imbibition-type fracturing fluid R60 and Chang 8 crude oil can reach 3.4×10 -3 mN / m, contact angle of about 75°, and the total efficiency of static imbibition displacement of the core is 35.64%.

[0006] In 2023, Zhang Jinfeng et al. published the "Influence of surfactants on the effect of high-temperature and high-pressure imbibition flooding in shale oil reservoirs". The interfacial tension of 0.1% FST-1 can reach 3.5×10 -3mN / m, contact angle 33.7°, and imbibition displacement efficiency exceeding 25%.

[0007] Patent CN115895630A: A kind of imbibition oil displacement agent and its preparation method, coupled imbibition fracturing fluid and its application. A kind of imbibition oil displacement agent, characterized by, by weight percentage, 2.0%-8.5% biosurfactant, 0.5%-10.0% nano-silica sol, 1.0%-6.0% cationic surfactant, 1.5%-5.5% coconut oil diethanolamine, 0.5%-1.5% sodium olefin sulfonate, 0.5%-2.5% polyoxyethylene, 1.5%-9.0% dipentene, 0.5%-3.0% polyquaternium salt, 3.0%-10.0% low-carbon alcohol, 5.0%-8.0% pentane, 1.0%-3.0% citric acid and the balance water. The contact angle tested is <90°, the interfacial tension is 10 -1 mN / m-10 -4 mN / m.

[0008] Patent CN115975621A: Fracturing fluid imbibition agent and fracturing fluid, characterized by the following raw materials for preparing the fracturing fluid imbibition agent, calculated by weight: 8-10 parts fatty alcohol polyoxyethylene ether, 0.8-1 part isotridecyl alcohol polyoxyethylene ether, 1-2.2 parts anionic surfactant, 0.5-1 part pH regulator, and 30-50 parts deionized water. The interfacial tension measured was 0.38mN / m-0.40mN / m, and the capillary self-priming height was 18.3mm-22.0mm.

[0009] Different from the existing literature, the important development direction of this technology is to study the imbibition materials with ultra-low interfacial energy and super strong wetting effect to further improve the recovery rate of shale and tight sandstone. Summary of the Invention

[0010] In view of this, the present invention proposes an oilfield imbibition washing microemulsion and a preparation method thereof, aiming to solve the problems of poor oil washing ability of conventional imbibition agents used in tertiary oil recovery and low recovery rate of microemulsion flooding.

[0011] The technical solution of the present invention is achieved as follows: The present invention provides an oilfield wicking washing oil microemulsion, wherein the raw materials, calculated by weight percentage, include 0.050%-0.075% of a dialkyl quaternary ammonium salt cationic surfactant, 0.226%-0.330% of a fatty amine polyoxyethylene ether, 0.035%-0.050% of a propylene glycol block polyether, 0.025%-0.055% of a naphthalenesulfonate formaldehyde polymer, and the balance is water.

[0012] In some embodiments, the dialkyl quaternary ammonium salt cationic surfactant includes at least one of di-C8-C12 alkyl dimethyl ammonium chloride or di-C8-C12 alkyl dimethyl ammonium chloride.

[0013] In some embodiments, the fatty amine polyoxyethylene ether includes at least one of laurylamine polyoxyethylene ether and octadecylamine polyoxyethylene ether.

[0014] In some embodiments, the dodecylamine polyoxyethylene ether includes at least one of dodecylamine polyoxyethylene ethers having 5, 10, and 15 repeating units of the oxyethylene ether.

[0015] In some embodiments, the model of the dodecylamine polyoxyethylene ether includes at least one of AC1205, AC1210, and AC1215.

[0016] In some embodiments, the octadecylamine polyoxyethylene ether includes at least one of octadecylamine polyoxyethylene ethers having 10, 12, 15, and 20 repeating units of oxyethylene ether.

[0017] In some embodiments, the model of the octadecylamine polyoxyethylene ether includes at least one of AC1810, AC1812, AC1815, and AC1820.

[0018] In some embodiments, the propylene glycol block polyether includes at least one of models L35, L45, L64, and L65.

[0019] In some embodiments, the naphthalenesulfonate formaldehyde polymer includes at least one of the types NNF2, NNF3, NNF4, and NNF5.

[0020] In some embodiments, the water has a salinity of 10,000 mg / L to 90,000 mg / L.

[0021] In a second aspect, the present invention also provides a method for preparing the above-mentioned oilfield wicking oil microemulsion, comprising the following steps: adding a dialkyl quaternary ammonium salt cationic surfactant, fatty amine polyoxyethylene ether, propylene glycol block polyether and naphthalenesulfonate formaldehyde polymer to water, and mixing them evenly to obtain the oilfield wicking oil microemulsion.

[0022] The present invention has the following beneficial effects compared to the prior art:

[0023] The oil field imbibition oil washing microemulsion of the present invention has an oil washing efficiency of greater than or equal to 67%, a sandstone recovery rate increased by 8.4% compared with water drive, and a shale recovery rate increased by 14.5%, and the effect of imbibition oil recovery is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is the imbibition map of sandstone in Experimental Example 5;

[0026] Figure 2 The relationship between sandstone recovery degree and imbibition time in Experimental Example 5;

[0027] Figure 3 This is the imbibition spectrum of shale with water of 30000 mg / L salinity in Experimental Example 7;

[0028] Figure 4 This is the imbibition spectrum of microemulsion on shale in Experimental Example 7;

[0029] Figure 5 This is the relationship between the recovery degree and imbibition time of shale for different liquids in Experimental Example 7. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0032] Unless otherwise specified, the methods used in the following examples are conventional methods. The materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, unless otherwise specified, and can be obtained commercially by those skilled in the art.

[0033] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range. In the present specification and claims, range definitions may be combined and / or interchanged, and if not otherwise stated, such ranges include all subranges contained therein.

[0034] The water used in the following examples was artificially prepared. The mineralization and ion composition of water of various mineralization degrees are shown in the following table:

[0035]

[0036] Example 1

[0037] This embodiment provides an oilfield imbibition washing oil microemulsion

[0038] Raw materials are calculated as 100% by weight and include:

[0039]

[0040] Preparation method of oilfield wicking and washing oil microemulsion:

[0041] Add dioctyldimethylammonium chloride, fatty amine polyoxyethylene ether AC1815, propylene glycol block polyether L65, and naphthalenesulfonate formaldehyde polymer NNF5 into water and mix well to obtain the product.

[0042] Example 2

[0043] This embodiment provides an oilfield imbibition washing oil microemulsion

[0044] Raw materials are calculated as 100% by weight and include:

[0045]

[0046] Preparation method of oilfield wicking and washing oil microemulsion:

[0047] Add didecyl dimethyl ammonium chloride, fatty amine polyoxyethylene ether AC1810, propylene glycol block polyether L64, and naphthalenesulfonate formaldehyde polymer NNF4 into water and mix well to obtain the product.

[0048] Example 3

[0049] This embodiment provides an oilfield imbibition washing oil microemulsion

[0050] Raw materials are calculated as 100% by weight and include:

[0051]

[0052] Preparation method of oilfield wicking and washing oil microemulsion:

[0053] Add didecyl dimethyl ammonium chloride, fatty amine polyoxyethylene ether AC1215, propylene glycol block polyether L45, and naphthalenesulfonate formaldehyde polymer NNF3 into water and mix well to obtain the product.

[0054] Example 4

[0055] This embodiment provides an oilfield imbibition washing oil microemulsion

[0056] Raw materials are calculated as 100% by weight and include:

[0057]

[0058] Preparation method of oilfield wicking and washing oil microemulsion:

[0059] Add didodecyl dimethyl ammonium chloride, fatty amine polyoxyethylene ether AC1210, propylene glycol block polyether L35, and naphthalenesulfonate formaldehyde polymer NNF2 into water and mix well to obtain the product.

[0060] Example 5

[0061] This embodiment provides an oilfield imbibition washing oil microemulsion

[0062] Raw materials are calculated as 100% by weight and include:

[0063]

[0064] Preparation method of oilfield wicking and washing oil microemulsion:

[0065] Add didodecyl dimethyl ammonium bromide, fatty amine polyoxyethylene ether AC1815, propylene glycol block polyether L65, and naphthalenesulfonate formaldehyde polymer NNF3 into water and mix well to obtain the product.

[0066] Experimental Example 1

[0067] Interfacial tension testing was performed on the microemulsions obtained in the above examples. The tension testing method was based on the method specified in the natural gas industry standard "SY / T 5370 Surface and Interfacial Tension Determination Method." Jiangsu crude oil was used for the test. The test results are shown in the following table:

[0068]

[0069] The data in the above table show that the interfacial tension of the microemulsion prepared by using Jiangsu crude oil and Examples 1-5 reached 10 -3 The order of mN / m reaches the ultra-low interface.

[0070] Experimental Example 2

[0071] The microemulsions obtained in the above examples were tested for wettability. The test method followed the natural gas industry standard, "SY / T 5153: Determination of Wettability of Reservoir Rocks." Jiangsu crude oil was used for the test. The test results are shown in the following table:

[0072]

[0073] The microemulsions prepared with Jiangsu crude oil and Examples 1-5 can achieve wetting reversal within 1 hour, with contact angles of ≤8.4°, transforming the oil-wet surface into a strongly water-wet surface.

[0074] Experimental Example 3

[0075] The microemulsions obtained in the above examples were tested for oil washing efficiency using the method specified in the Sinopec corporate standard "Q / SH CG0079-2021 Technical Requirements for Surfactants for Oil Displacement." The oil washing efficiency of the microemulsions prepared with Jiangsu crude oil and Examples 1-5 at 60°C is shown in the following table:

[0076]

[0077] The data in the above table show that the microemulsion prepared by the preparation method of the present invention has an oil washing efficiency of ≥67% for Jiangsu crude oil, and the oil washing effect is good.

[0078] Experimental Example 4

[0079] The microemulsions prepared in the above examples were respectively tested for their tight sandstone imbibition efficiency. The test was conducted using a weighing method in the following steps:

[0080] Step 1: Accurately measure the length, diameter and dry weight of the core, and weigh it after washing and drying with oil.

[0081] Step 2: Test the core porosity and calculate the core pore volume according to the method specified in GB / T 29172 V 0.

[0082] Step 3: Place the core in a high-temperature, high-pressure vacuum saturation device and evacuate for 24 hours. Pressurize the core at 60°C and saturate with Jiangsu crude oil at 20 MPa for 5 days. The volume of the saturated oil phase in the core is recorded as V 0.

[0083] Step 4: Measure the density of the microemulsions prepared in Examples 1-5 ρ 0.

[0084] Step 5: The core saturated with Jiangsu crude oil was immersed in an imbibition bottle filled with the microemulsion prepared in Example 1-5, and an imbibition experiment was carried out at 60°C. The mass of the core sample was measured in real time using a high-precision balance. The mass of the core at the beginning of the experiment was recorded as m 0, the core mass at time t is recorded as m t , the mass difference is recorded as Δ m When the values ​​of three consecutive recording points with an interval of 2 hours do not change, the experiment ends. The recovery rate is calculated according to the formula R t .

[0085] R t =Δ m / [(1- ρ 0)* V 0]

[0086] Where: Δ m is the mass change of the core sample at time t, g;

[0087] ρ 0 is the density of the microemulsion, g / cm 3 ;

[0088] R t is the recovery rate of the core sample by the imbibition agent at time t, %;

[0089] V 0 is the volume of crude oil saturated by the core, cm 3 .

[0090] The core size used was 6 cm long and 2.5 cm in diameter.

[0091] According to the above test method, the recovery rates of the microemulsions prepared in Examples 1-5 are shown in the following table:

[0092]

[0093] It is not difficult to see from the above data that the recovery rate of the microemulsion prepared by the solution of the present application is ≥67.1%.

[0094] Experimental Example 5

[0095] The microemulsion prepared in Example 3 was used to perform an online nuclear magnetic absorption test on tight sandstone. The core was 4.02 cm long and 2.51 cm in diameter; the porosity was 7.32% and the permeability was 1.32 md; the absorption conditions were normal pressure and temperature 60°C; the absorption spectrum was as follows: Figure 1 As shown in the figure, the relationship between the recovery degree and the imbibition time is as follows: Figure 2 As shown, after 15 days of testing, the calculated recovery factor (extraction degree) is 69.1%.

[0096] Experimental Example 6

[0097] Follow the methods specified in the petroleum and natural gas industry standard "SY / T 5862 Technical Requirements for Polymers for Oil Displacement." Simulated formation water was injected at a flow rate of 0.1 mL / min until the water cut at the production end exceeded 98%. After injecting 1 PV of the microemulsion prepared in Example 2 at a flow rate of 0.1 mL / min, subsequent water flooding was performed until the water cut exceeded 98%. The oil displacement efficiency was then calculated.

[0098] A natural sandstone core with a length of 8 cm and a diameter of 2.5 cm was used. The core had a porosity of 8.5%, a permeability of 2.3 mD, and a temperature of 60°C. The core flooding method was used to conduct the test. The water flooding recovery rate of the core was 45.2%. After adding the microemulsion flooding agent, the recovery rate reached 53.6%, an increase of 8.4% compared with water flooding, and the oil displacement effect was obvious.

[0099] Experimental Example 7

[0100] The online NMR absorption efficiency comparison test of microemulsion shale was conducted. The core size, porosity and permeability data are shown in the following table. The experimental temperature is 60℃ and the pressure is 15MPa. The absorption spectrum of shale with 30000mg / L water is shown in the following table. Figure 3 , Example 2 Microemulsion Imbibition Spectrum on Shale Figure 4 The relationship between recovery degree and imbibition time is as follows: Figure 5 The recovery rate is calculated as shown in the following table. The recovery rate of shale with 30,000 mg / L water is 15.1%, while the recovery rate of shale with the microemulsion in Example 2 is 29.6%, which increases the recovery rate (recovery rate) by 14.5%.

[0101]

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An oilfield imbibition wash oil microemulsion, characterized in that: The composition comprises, by weight percentage, 0.050%-0.075% of a dialkyl quaternary ammonium salt cationic surfactant, 0.226%-0.330% of a fatty amine polyoxyethylene ether, 0.035%-0.050% of a propylene glycol block polyether, 0.025%-0.055% of a naphthalenesulfonate formaldehyde polymer, and the balance being water.

2. The oilfield imbibition washing oil microemulsion according to claim 1, wherein The dialkyl quaternary ammonium salt cationic surfactant includes at least one of di-C8-C12 alkyl dimethyl ammonium chloride or di-C8-C12 alkyl dimethyl ammonium chloride.

3. The oilfield imbibition wash oil microemulsion according to claim 1, wherein The fatty amine polyoxyethylene ether includes at least one of laurylamine polyoxyethylene ether and octadecylamine polyoxyethylene ether.

4. The oilfield imbibition wash oil microemulsion according to claim 3, wherein The dodecylamine polyoxyethylene ether includes at least one of dodecylamine polyoxyethylene ethers having 5, 10, and 15 repeating units of the oxyethylene ether.

5. The oilfield imbibition washing oil microemulsion according to claim 3, wherein The octadecylamine polyoxyethylene ether includes at least one of octadecylamine polyoxyethylene ethers having 10, 12, 15, and 20 repeating units of the oxyethylene ether.

6. The oilfield imbibition wash oil microemulsion according to claim 1, wherein The propylene glycol block polyether includes at least one of the models L35, L45, L64, and L65.

7. The oilfield imbibition wash oil microemulsion according to claim 1, wherein The naphthalenesulfonate formaldehyde polymer includes at least one of the models NNF2, NNF3, NNF4 and NNF5.

8. The oilfield imbibition wash oil microemulsion according to claim 1, wherein The mineralization of the water is 10000 mg / L-90000 mg / L.

9. The method for preparing the oilfield imbibition wash oil microemulsion according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: adding dialkyl quaternary ammonium salt cationic surfactant, fatty amine polyoxyethylene ether, propylene glycol block polyether and naphthalene sulfonate formaldehyde polymer into water and mixing them evenly to obtain oilfield wicking oil washing microemulsion.

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