A full-fiber composite oil displacement composition, and a preparation method and application thereof

Abstract

The application provides a full-fiber composite oil displacement composition and a preparation method and application thereof, and components of the full-fiber composite oil displacement composition include, in percentage by mass, nanocellulose 0.01wt%-0.1wt%, cellulose derivative 0.05wt%-0.5wt%, and water 90wt%-99.9wt%. The full-fiber composite oil displacement composition provided by the application can greatly improve the stability and viscosity of an emulsion. The composition is based on cellulose nanomaterials and crude oil which are adsorbed on an oil-water interface through hydrogen bonds, CH2-pi interactions and the like, a three-dimensional barrier is formed on the oil-water interface, coalescence of droplets is hindered, and thus the emulsion state is stabilized, the viscosity of the crude oil is improved, and the recovery rate is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field development, and particularly relates to a full-fiber composite oil displacement composition and a preparation method and application thereof. BACKGROUND

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

[0003] CN114456332A discloses a kind of nano particle modified polymer and its preparation method and application.The polymer includes acrylamide structural unit shown in formula (I), vinyl modified nano particle structural unit shown in formula (II) and N-alkyl acrylamide structural unit shown in formula (III):The polymer has certain water phase tackifying capacity, reduces interfacial tension and thereby emulsifies crude oil characteristics, solves the problems of other general oil displacement polymer insufficient viscosity, difficult to effectively establish underground seepage resistance, and weak interaction with crude oil molecules, suitable for tertiary oil recovery of land oil field heavy oil reservoir.

[0004] CN114479807A discloses an organic nano particle / surfactant composite wetting agent and its preparation method, the wetting agent is a composite of organic nano particles and surfactants, and the organic nano particles are self-polymerized particles of catecholamine compounds.The composite obtained by the interaction of multiple sites on the surface of organic nano particles and surfactants can improve the hydrophilicity of core and the wettability of oil reservoir at low concentration, which has important application value in tertiary oil recovery.

[0005] However, most of the nano particles used for nano oil displacement at present have complex synthesis steps and involve the use of hazardous reagents, which can cause great burden to the environment and human body. Therefore, it is necessary to develop a green nano material with wide sources and simple preparation method for oil development. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a full-fiber composite oil displacement composition and a preparation method and application thereof, which enhances the emulsifying capacity of the nano composite oil displacement system by introducing nano particles, realizes efficient oil washing and emulsification to expand sweep, and improves the recovery rate, which has important significance for efficient development of medium and low permeability reservoirs.

[0007] To achieve the purpose of the present application, the following technical solutions are adopted:

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

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

[0010] Nanoparticle oil displacement is an emerging chemical oil displacement technology, which has a large specific surface area and surface energy, and greatly reduces the oil-water interfacial tension by adsorbing on the oil-water section, so that crude oil is easily peeled into small oil droplets and is displaced by the displacement fluid. On the other hand, nanoparticles have a certain temporary plugging effect on small pores, thereby expanding the swept volume and further improving the recovery rate, which has important significance for the continued development of some low-permeability oilfields.

[0011] The full-fiber composite oil displacement composition obtained by combining nanocellulose and cellulose derivatives in the present application has amphiphilic properties, high specific area, and excellent mechanical properties, which can be adsorbed on the oil-water interface by hydrogen bonding, CH2-π interaction, etc. and form a three-dimensional barrier on the oil-water interface, hinder the coalescence of droplets, thereby stabilizing the emulsion state, increasing the viscosity of crude oil, and improving the recovery rate.

[0012] The mass percentage of the nanocellulose in the full-fiber composite oil displacement composition of the present application can 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 can 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 can be 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, 99wt%, 99.5wt%, or 99.8wt%, etc.

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

[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 defibrating cellulose raw materials.

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

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

[0020] Preferably, the nanocellulose has a length of 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, etc.

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

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

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

[0024] In the present application, when the cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose, no agglomeration phenomenon occurs after the combination with nanocellulose, and the emulsification effect of the composition on 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] Specific point values within the above numerical range can be selected, which will not be described here one by one.

[0030] In a second aspect, the present application provides a preparation method of the full-fiber composite oil displacement composition according to the first aspect, wherein the nanocellulose, the cellulose derivative and the water are mixed, stirred and dispersed, and uniformly obtained as the full-fiber composite oil displacement composition.

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

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

[0033] Specific point values within the above numerical ranges can be selected, which will not be described here one by one.

[0034] In a third aspect, the present application provides an application of the full-fiber composite oil displacement composition according to the first aspect in oil exploitation.

[0035] Preferably, the oil exploitation is in the tertiary oil recovery stage.

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

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

[0038] (1) The full-fiber composite oil displacement composition provided by the present application is green and environmentally friendly, and the preparation method is simple and practical.

[0039] (2) The full-fiber composite oil displacement composition provided by the present application can greatly improve the stability and viscosity of the emulsion. The composition is based on cellulose nanomaterials and crude oil adsorbed on the oil-water interface through hydrogen bonds, CH2-π interactions and the like, forming a three-dimensional barrier on the oil-water interface, hindering the coalescence of droplets, thereby stabilizing the emulsion state, improving the viscosity of the crude oil, and improving the recovery rate. DETAILED DESCRIPTION

[0040] The following examples are used to illustrate the present application, but are not used to limit the scope of the present application. If the specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art, or according to the product instruction. If the manufacturer of the used instruments is not specified, it is a conventional product that can be purchased through a regular channel.

[0041] In the embodiments of this invention, any other raw materials can be used as long as they are purchased from authorized distributors.

[0042] Example 1

[0043] This embodiment provides a full-fiber composite oil displacement composition, which, by mass percentage, comprises: 0.05 wt% nanocellulose, 0.2 wt% cellulose derivative, and the balance being 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 includes:

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

[0047] (2) The nanocellulose, cellulose derivative and water are mixed by mass percentage and ultrasonically stirred and dispersed, wherein the ultrasonic power is 400w, the stirring speed is 800r / min, the dispersion time is 30min, and the whole fiber composite oil displacement composition is obtained after uniformity.

[0048] Example 2

[0049] This embodiment provides a full-fiber composite oil displacement composition, which, by mass percentage, comprises: 0.01 wt% nanocellulose, 0.3 wt% cellulose derivative, and the balance being 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 includes:

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

[0053] (2) The nanocellulose, cellulose derivative and water are mixed by mass percentage and ultrasonically stirred and dispersed, wherein the ultrasonic power is 500w, the stirring speed is 600r / min, the dispersion time is 20min, and the whole fiber composite oil displacement composition is obtained after uniformity.

[0054] Example 3

[0055] The embodiment provides a full-fiber composite oil displacement composition, which comprises, in percentage by mass, 0.03wt% of nanocellulose, 0.1wt% of cellulose derivative, and the rest of water.

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

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

[0058] (1) wood pulp is subjected to ultrasonic treatment for 30 min under a power of 1500W, so that nanocellulose with a length of 4±0.5um and a diameter of 40±5nm is prepared;

[0059] (2) the nanocellulose, the cellulose derivative and water are mixed in percentage by mass, and are uniformly dispersed through ultrasonic stirring, wherein the ultrasonic power is 400w, the stirring speed is 900r / min, and the dispersion time is 40min, so that the full-fiber composite oil displacement composition is obtained.

[0060] Embodiment 4

[0061] The embodiment provides a full-fiber composite oil displacement composition, which is different from the composition in embodiment 1 only in that the cellulose derivative is a combination of sodium alginate and hydroxypropyl cellulose with a mass ratio of 0.7:2.5, the addition amount of the cellulose derivative remains unchanged, and the rest of components remain consistent with those in embodiment 1, and the preparation method refers to embodiment 1.

[0062] Embodiment 5

[0063] The embodiment provides a full-fiber composite oil displacement composition, which is different from the composition in embodiment 1 only in that the cellulose derivative is a combination of chitosan and hydroxypropyl cellulose with a mass ratio of 0.8:2.5, the addition amount of the cellulose derivative remains unchanged, and the rest of components remain consistent with those in embodiment 1, and the preparation method refers to embodiment 1.

[0064] Embodiment 6

[0065] The embodiment provides a full-fiber composite oil displacement composition, which is different from the composition in embodiment 1 only in that the cellulose derivative is a combination of chitosan and sodium alginate with a mass ratio of 0.8:0.7, the addition amount of the cellulose derivative remains unchanged, and the rest of components remain consistent with those in embodiment 1, and the preparation method refers to embodiment 1.

[0066] Embodiment 7

[0067] The present example provides a full-fiber composite oil displacement composition, which is only different from example 1 in that the length of the nanocellulose is 35±0.5 μm; the diameter is 30±5 nm, and the amount of nanocellulose is kept unchanged, and the rest of the components are consistent with example 1, and the preparation method refers to example 1.

[0068] Example 8

[0069] The present example provides a full-fiber composite oil displacement composition, which is only different from example 1 in that the length of the nanocellulose is 3±0.5 μm; the diameter is 350±5 nm, and the amount of nanocellulose is kept unchanged, and the rest of the components are consistent with example 1, and the preparation method refers to example 1.

[0070] Comparative Example 1

[0071] The present comparative example provides an oil displacement agent, which is only different from example 1 in that it does not include cellulose derivatives, and the reduced amount is supplemented by nanocellulose, and the rest of the components are consistent with example 1, and the preparation method refers to example 1.

[0072] Comparative Example 2

[0073] The present comparative example provides an oil displacement agent, which is only different from example 1 in that it does not include nanocellulose, and the reduced amount is supplemented by cellulose derivatives, and the rest of the components are consistent with example 1, and the preparation method refers to example 1.

[0074] Test Example 1

[0075] The emulsion viscosity and stability of the full-fiber composite oil displacement composition of examples 1-8 and the oil displacement agent of comparative examples 1-2 and crude oil are tested.

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

[0077] Table 1

[0078]

[0079]

[0080] Table 2

[0081]

[0082] From the data of Table 1 and 2, it can be seen that the full fiber composite oil displacement composition obtained by Examples 1-3 can emulsify oil and water to form stable water-in-oil emulsion when the oil-water volume ratio is below 2:8, and the viscosity of the emulsion gradually increases with the increase of the oil-water ratio, and the highest is more than 50 times the viscosity of crude oil. It shows that the full fiber composite oil displacement composition of the present application can well stabilize the emulsion state, increase the viscosity of crude oil and improve the recovery rate.

[0083] From Examples 4-6, it can be seen that when the cellulose derivative is not the specific combination of the present application, the highest water content of the full fiber composite oil displacement composition combined with crude oil can only reach 50%, and the viscosity increasing effect of crude oil is slightly decreased.

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

[0085] From Comparative Examples 1-2, it can be seen that when only nanocellulose or cellulose derivative is used as oil displacement agent, the highest water content after combined with crude oil can only reach 30%, and the emulsification effect with crude oil is obviously poor, and the viscosity of crude oil is also not obviously improved.

[0086] The applicant declares that the full fiber composite oil displacement composition, its preparation method and application of the present application are illustrated by the above examples, but the present application is not limited to the above detailed process flow, that is, it does not mean that the present application must rely on the above detailed process flow to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the scope of protection and disclosure of the present application.

Claims

1. A fully fiber-based composite oil displacement composition, characterized in that, The components of the all-fiber composite oil displacement composition, by weight percentage, include: Nanocellulose 0.01wt%-0.1wt%, cellulose derivatives 0.05wt%-0.5wt%, and water 90wt%-99.9wt%; The length of the nanocellulose is 500 nm-10 μm; The diameter of the nanocellulose is 10nm-50nm; The cellulose derivative is a combination of chitosan, sodium alginate and hydroxypropyl cellulose; The mass ratio of chitosan, sodium alginate and hydroxypropyl cellulose is (0.5-1):(0.5-1):(1-3).

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

3. The all-fiber composite oil displacement composition according to claim 1, characterized in that, The nanocellulose is obtained by mechanically decelluloseing cellulose raw materials.

4. The all-fiber composite oil displacement composition according to claim 3, characterized in that, The cellulose raw materials include any one or a combination of at least two of corn cobs, pulp, wood pulp, cotton, or hemp.

5. The all-fiber composite oil displacement composition according to claim 3, characterized in that, The mechanical defiberization includes any one of high-intensity ultrasonic treatment, high-speed stirring treatment, high-speed grinding treatment, or high-pressure homogenization treatment.

6. The method for preparing the all-fiber composite oil displacement composition according to any one of claims 1-5, characterized in that, The all-fiber composite oil displacement composition is obtained by mixing nanocellulose, cellulose derivatives and water, stirring and dispersing.

7. The method for preparing the all-fiber composite oil displacement composition according to claim 6, characterized in that, The stirring and dispersion is ultrasonic stirring and dispersion.

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

9. The application of the all-fiber composite oil displacement composition according to any one of claims 1-5 in oil extraction.

10. The application according to claim 9, characterized in that, The oil extraction described is a tertiary oil recovery stage.

11. The application according to claim 9, characterized in that, The all-fiber composite oil displacement composition is used directly as an oil displacement agent.

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