All-fiber composite oil displacement composition as well as preparation method and application thereof

Abstract

The invention provides an all-fiber composite oil displacement composition as well as a preparation method and application thereof, and the all-fiber composite oil displacement composition comprises the following components in percentage by mass: 0.01 wt%-0.1 wt% of nano cellulose, 0.05 wt%-0.5 wt% of a cellulose derivative and 90 wt%-99.9 wt% of water. The all-fiber composite oil displacement composition provided by the invention can greatly improve the stability and viscosity of an emulsion. The composition is adsorbed on an oil-water interface based on the cellulose nanomaterial and crude oil through interaction of hydrogen bonds, CH2-pi and the like, a three-dimensional barrier is formed on the oil-water interface, liquid drop coalescence is hindered, and therefore the emulsion state is stabilized, the viscosity of the crude oil is improved, and the recovery rate is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field exploitation, and specifically relates to an all-fiber composite oil displacement composition and a preparation method and application thereof. Background Art

[0002] At present, most of my country's old oil fields have entered a period of high water content and rapid decline in production. Due to the difficulty in improving the flow ratio and reservoir heterogeneity in secondary oil recovery, crude oil is bound by capillary force or bypass, resulting in low sweep efficiency, so that the crude oil remaining in the pore cannot be displaced. Tertiary oil recovery technology solves the main problems such as low sweep efficiency and difficulty in changing rock formation wettability, and can effectively improve the displacement effect, thereby increasing crude oil recovery.

[0003] CN114456332A discloses a nanoparticle-modified polymer and its preparation method and application. The polymer comprises an acrylamide structural unit shown in formula (I), a vinyl-modified nanoparticle structural unit shown in formula (II) and an N-alkyl acrylamide structural unit shown in formula (III): the polymer has a certain ability to increase viscosity in the water phase, reduce interfacial tension and thus emulsify crude oil, and solves the problems of other general oil recovery polymers that are insufficient in viscosity, difficult to effectively establish underground seepage resistance, and weak interaction with crude oil molecules, and is suitable for tertiary oil recovery in heavy oil reservoirs in onshore oil fields.

[0004] CN114479807A discloses an organic nanoparticle / surfactant composite wetting agent and a preparation method thereof, wherein the wetting agent is a composite of organic nanoparticles and surfactants, and the organic nanoparticles are self-polymerized particles of catecholamine compounds. The invention obtains a composite through the interaction between multiple sites on the surface of organic nanoparticles and surfactants, and its dispersion can improve the hydrophilicity of the core and the wetting performance of the oil reservoir at a low concentration, and has important application value in tertiary oil recovery.

[0005] However, most of the nanoparticles currently used for nano-oil flooding have complicated synthesis steps and involve the use of hazardous reagents, which can easily cause a great burden on the environment and human body. Based on this, it is necessary to develop a green nanomaterial with a wide source and simple preparation method for oil development. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a full-fiber composite oil-displacing composition and a preparation method and application thereof. The composition enhances the emulsification ability of the nano-composite oil-displacing system by introducing nanoparticles, thereby achieving efficient oil washing and emulsification expansion, thereby improving the recovery rate, which is of great significance for the efficient development of medium and low permeability oil reservoirs.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a full-fiber composite oil displacement composition, wherein the components of the full-fiber composite oil displacement composition include, by mass percentage:

[0009] Nanocellulose 0.01wt%-0.1wt%, cellulose derivative 0.05wt%-0.5wt% and water 90wt%-99.9wt%.

[0010] Nanoparticle flooding is an emerging chemical flooding technology. It has a large specific surface area and surface energy. By adsorbing on the oil-water cross section, it greatly reduces the oil-water interfacial tension, making it easy for crude oil to peel off into small oil droplets and be displaced by the displacement fluid. On the other hand, nanoparticles have a certain temporary blocking effect on small pores, thereby expanding the swept volume and thus improving the recovery rate, which is of great significance for the continued development of some low-permeability oil fields.

[0011] The full-fiber composite oil-displacing composition obtained by combining nanocellulose and cellulose derivatives in the present invention has amphiphilicity, high specific area and excellent mechanical properties. It can be adsorbed on the oil-water interface with crude oil through hydrogen bonds, CH2-π interactions, etc., forming a three-dimensional barrier at the oil-water interface to hinder droplet aggregation, thereby stabilizing the emulsion state, increasing crude oil viscosity, and improving recovery.

[0012] The mass percentage of the nanocellulose in the full-fiber composite oil-displacing composition of the present invention may be 0.02wt%, 0.03wt%, 0.04wt%, 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt% or 0.09wt%, etc.;

[0013] The mass percentage of the cellulose derivative may be 0.08wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt% or 0.45wt%, etc.

[0014] The mass percentage of the water may be 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, 99wt%, 99.5wt% or 99.8wt%, etc.

[0015] Preferably, in terms of mass percentage, the components of the all-fiber composite oil displacement composition include:

[0016] Nanocellulose 0.01wt%-0.05wt%, cellulose derivative 0.05wt%-0.3wt% and water 90wt%-99.9wt%.

[0017] Preferably, the nanocellulose is obtained by mechanically defibrillating cellulose raw materials;

[0018] Preferably, the cellulose raw material comprises any one of corn cobs, pulp, wood pulp, cotton or hemp, or a combination of at least two thereof.

[0019] Preferably, the mechanical defibration includes any one of high-intensity ultrasonic treatment, high-speed stirring treatment, high-speed grinding treatment or high-pressure homogenization treatment.

[0020] Preferably, the length of the nanocellulose is 500 nm-10 μm, for example, 600 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm or 9 μm.

[0021] Preferably, the diameter of the nanocellulose is 10 nm-50 nm, for example, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm or 45 nm.

[0022] Preferably, the cellulose derivative includes any one of starch, chitosan, sodium alginate or hydroxypropyl cellulose or a combination of at least two thereof.

[0023] Preferably, the cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose.

[0024] In the present invention, when the cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose, it will not agglomerate after being combined with nanocellulose, and the emulsification effect of the composition and crude oil can be better improved.

[0025] Preferably, the mass ratio of chitosan, sodium alginate and hydroxypropyl cellulose is (0.5-1):(0.5-1):(1-3).

[0026] The first "0.5-1" can be 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or 0.95, etc.;

[0027] The second "0.5-1" can be 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or 0.95, etc.;

[0028] “1-3” can be 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6 or 2.8, etc.

[0029] Any specific point value within the above numerical range can be selected, and will not be described in detail here.

[0030] In a second aspect, the present invention provides a method for preparing the full-fiber composite oil-displacing composition according to the first aspect, comprising mixing nanocellulose, a cellulose derivative and water, stirring and dispersing them, and obtaining the full-fiber composite oil-displacing composition after uniform distribution.

[0031] Preferably, the stirring and dispersing is ultrasonic stirring and dispersing.

[0032] Preferably, the ultrasonic power is 300-500W, the stirring speed is 600-900r / min, and the dispersion time is 20-40min. For example, the ultrasonic power can be 320w, 350w, 400w, 450w or 480w, etc., the stirring speed can be 650r / min, 700r / min, 750r / min, 800r / min or 850r / min, etc., and the dispersion time can be 22min, 25min, 28min, 30min, 32min, 35min or 38min, etc.

[0033] Any specific point value within the above numerical range can be selected, and will not be described in detail here.

[0034] In a third aspect, the present invention provides a use of the all-fiber composite oil-displacing composition according to the first aspect in oil production.

[0035] Preferably, the oil recovery is a tertiary oil recovery stage;

[0036] Preferably, the all-fiber composite oil-displacing composition is directly used as an oil-displacing agent.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The all-fiber composite oil-displacing composition provided by the present invention is green and environmentally friendly, and has a simple preparation method and strong practicality.

[0039] (2) The all-fiber composite oil displacement composition provided by the present invention can greatly improve the stability and viscosity of the emulsion. The composition is based on the adsorption of cellulose nanomaterials and crude oil at the oil-water interface through hydrogen bonds, CH2-π interactions, etc., forming a three-dimensional barrier at the oil-water interface to hinder the aggregation of droplets, thereby stabilizing the emulsion state, increasing the viscosity of crude oil, and improving the recovery rate. DETAILED DESCRIPTION

[0040] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If the manufacturers of the instruments used are not specified, they are all conventional products that can be purchased through regular channels.

[0041] The remaining raw materials in the embodiments of the present invention can be used as long as they are purchased from regular dealers.

[0042] Example 1

[0043] This embodiment provides a full-fiber composite oil-displacing composition, which comprises, by weight percentage: 0.05 wt% of nanocellulose, 0.2 wt% of cellulose derivative, and the balance is water;

[0044] The cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose in a mass ratio of 0.8:0.7:2.5.

[0045] The preparation method of the all-fiber composite oil displacement composition comprises:

[0046] (1) The wood pulp was ultrasonically treated at a power of 1500 W for 30 min to prepare nanocellulose with a length of 3±0.5 μm and a diameter of 30±5 nm;

[0047] (2) Mixing nanocellulose, cellulose derivatives and water according to mass percentage, and dispersing them by ultrasonic stirring, wherein the ultrasonic power is 400 W, the stirring speed is 800 r / min, and the dispersion time is 30 min, and the full-fiber composite oil displacement composition is obtained after being uniformly dispersed.

[0048] Example 2

[0049] This embodiment provides a full-fiber composite oil-displacing composition, which comprises, by weight percentage: 0.01 wt% of nanocellulose, 0.3 wt% of cellulose derivative, and the balance is water;

[0050] The cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose in a mass ratio of 0.5:1:2.

[0051] The preparation method of the all-fiber composite oil displacement composition comprises:

[0052] (1) The wood pulp was ultrasonically treated at a power of 1500 W for 30 min to prepare nanocellulose with a length of 5±0.5 μm and a diameter of 45±5 nm;

[0053] (2) Mixing nanocellulose, cellulose derivatives and water according to mass percentage, and dispersing them by ultrasonic stirring, wherein the ultrasonic power is 500 W, the stirring speed is 600 r / min, and the dispersion time is 20 min, and the full-fiber composite oil-displacing composition is obtained after being uniformly dispersed.

[0054] Example 3

[0055] This embodiment provides a full-fiber composite oil-displacing composition, which comprises, by weight percentage: 0.03 wt % of nanocellulose, 0.1 wt % of cellulose derivative, and the balance of water;

[0056] The cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose in a mass ratio of 1:0.5:1.

[0057] The preparation method of the all-fiber composite oil displacement composition comprises:

[0058] (1) The wood pulp was ultrasonically treated at a power of 1500 W for 30 min to prepare nanocellulose with a length of 4±0.5 μm and a diameter of 40±5 nm;

[0059] (2) Mixing nanocellulose, cellulose derivatives and water according to mass percentage, and dispersing them by ultrasonic stirring, wherein the ultrasonic power is 400 W, the stirring speed is 900 r / min, and the dispersion time is 40 min, and the full-fiber composite oil-displacing composition is obtained after being uniformly dispersed.

[0060] Example 4

[0061] This embodiment provides a full-fiber composite oil-displacing composition, the difference between the composition and Example 1 is the combination of sodium alginate and hydroxypropyl cellulose in a mass ratio of 0.7:2.5 of the cellulose derivative, and the addition amount of the cellulose derivative is kept unchanged, and the other components are consistent with Example 1. The preparation method refers to Example 1.

[0062] Example 5

[0063] This embodiment provides a full-fiber composite oil-displacing composition, the difference between the composition and Example 1 is the combination of chitosan and hydroxypropyl cellulose in a mass ratio of 0.8:2.5 of the cellulose derivatives, and the addition amount of the cellulose derivatives is kept unchanged, and the other components are consistent with Example 1. The preparation method refers to Example 1.

[0064] Example 6

[0065] This embodiment provides a full-fiber composite oil-displacing composition, the difference between the composition and Example 1 is the combination of chitosan and sodium alginate in a mass ratio of 0.8:0.7 of the cellulose derivative, and the addition amount of the cellulose derivative is kept unchanged, and the other components are consistent with Example 1. The preparation method refers to Example 1.

[0066] Example 7

[0067] This embodiment provides a full-fiber composite oil-displacing composition, the difference between the composition and Example 1 is that the length of the nanocellulose is 35±0.5μm; the diameter is 30±5nm, and the added amount of nanocellulose is kept unchanged, the other components are consistent with Example 1, and the preparation method refers to Example 1.

[0068] Example 8

[0069] This embodiment provides a full-fiber composite oil-displacing composition, the difference between the composition and Example 1 is that the length of the nanocellulose is 3±0.5 μm; the diameter is 350±5 nm, and the amount of nanocellulose added is kept unchanged, the other components are consistent with Example 1, and the preparation method refers to Example 1.

[0070] Comparative Example 1

[0071] This comparative example provides an oil-displacing agent, which differs from Example 1 only in that the oil-displacing agent does not include a cellulose derivative, and the reduced amount is supplemented by nanocellulose. The remaining components are consistent with Example 1, and the preparation method refers to Example 1.

[0072] Comparative Example 2

[0073] This comparative example provides an oil-displacing agent, which differs from Example 1 only in that nanocellulose is not included, and the reduced amount is supplemented by cellulose derivatives, and the remaining components are consistent with Example 1. The preparation method refers to Example 1.

[0074] Test Example 1

[0075] The viscosity and stability of the emulsions formed by the full-fiber composite oil-displacing compositions of Examples 1-8 and the oil-displacing agents of Comparative Examples 1-2 and crude oil were tested.

[0076] The samples of Examples 1-8 and Comparative Example 12 were placed in beakers with crude oil (Changqing Oilfield crude oil) at a volume ratio of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1, respectively, kept at 55°C for 1 hour, dispersed with an IKA homogenizer for 1 minute, the emulsification was observed, and the apparent viscosity of the emulsion was tested with a rheometer. The test temperature was 55°C and the shear rate was 10s-1. The results are shown in Tables 1-2.

[0077] Table 1

[0078]

[0079]

[0080] Table 2

[0081]

[0082] From the data in Tables 1 and 2, it can be seen that when the oil-water volume ratio of the full-fiber composite oil-displacing composition obtained in Examples 1-3 is below 2:8, the oil and water can be emulsified to form a stable water-in-oil emulsion, and the viscosity of the emulsion gradually increases with the increase of the oil-water ratio, and the maximum value exceeds 50 times the viscosity of crude oil. It shows that the full-fiber composite oil-displacing composition of the present invention can stabilize the emulsion state well, increase the viscosity of crude oil, and improve the recovery rate.

[0083] It can be seen from Examples 4-6 that when the cellulose derivative is not the specific combination of the present invention, the maximum water content of the full-fiber composite oil-displacing composition after combining with crude oil can only reach 50%, and the effect of increasing crude oil viscosity is slightly reduced.

[0084] It can be seen from Examples 7-8 that the aspect ratio of nanocellulose also affects the emulsification performance of the composition. Too high or too low aspect ratio will reduce its effect of increasing crude oil viscosity.

[0085] It can be seen from Comparative Examples 1-2 that when only nanocellulose or cellulose derivatives are used as oil displacing agents, the maximum water content after combining with crude oil can only reach 30%, the emulsification effect with crude oil is significantly poor, and the increase in crude oil viscosity is not obvious.

[0086] The applicant declares that the present invention illustrates a full-fiber composite oil-displacing composition and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A full-fiber composite oil-displacing composition, characterized in that: In terms of mass percentage, the components of the all-fiber composite oil displacement composition include: Nanocellulose 0.01wt%-0.1wt%, cellulose derivative 0.05wt%-0.5wt% and water 90wt%-99.9wt%.

2. The all-fiber composite oil-displacing composition according to claim 1, characterized in that: In terms of mass percentage, the components of the all-fiber composite oil displacement composition include: Nanocellulose 0.01wt%-0.05wt%, cellulose derivative 0.05wt%-0.3wt% and water 90wt%-99.9wt%.

3. The all-fiber composite oil-displacing composition according to claim 1 or 2, characterized in that: The nanocellulose is obtained by mechanically defibrating cellulose raw materials; Preferably, the cellulose raw material comprises any one of corn cob, pulp, wood pulp, cotton or hemp, or a combination of at least two thereof; Preferably, the mechanical defibration includes any one of high-intensity ultrasonic treatment, high-speed stirring treatment, high-speed grinding treatment or high-pressure homogenization treatment.

4. The full-fiber composite oil-displacing composition according to claim 1-3, characterized in that: The length of the nanocellulose is 500nm-10μm; Preferably, the diameter of the nanocellulose is 10nm-50nm.

5. The full-fiber composite oil-displacing composition according to any one of claims 1 to 4, characterized in that: The cellulose derivative includes any one of starch, chitosan, sodium alginate or hydroxypropyl cellulose or a combination of at least two thereof.

6. The all-fiber composite oil-displacing composition according to claim 5, characterized in that: The cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose; Preferably, the mass ratio of chitosan, sodium alginate and hydroxypropyl cellulose is (0.5-1):(0.5-1):(1-3).

7. The method for preparing the full-fiber composite oil-displacing composition according to any one of claims 1 to 6, characterized in that: The nanocellulose, cellulose derivatives and water are mixed, stirred and dispersed to obtain the full-fiber composite oil displacement composition.

8. The method for preparing the full-fiber composite oil-displacing composition according to claim 7, characterized in that: The stirring and dispersing is ultrasonic stirring and dispersing; Preferably, the ultrasonic power is 300-500 W, the stirring speed is 600-900 r / min, and the dispersion time is 20-40 min.

9. Use of the full-fiber composite oil-displacing composition according to any one of claims 1 to 6 in oil production.

10. The use according to claim 9, characterized in that: The oil production is the tertiary oil production stage; Preferably, the all-fiber composite oil-displacing composition is directly used as an oil-displacing agent.

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