Method for separating crude oil asphaltene subcomponents

文档序号:1264828 发布日期:2020-08-25 浏览:27次 中文

阅读说明:本技术 一种分离原油沥青质次组分的方法 (Method for separating crude oil asphaltene subcomponents ) 是由 刘俊杰 李�杰 赛彦明 卢远琪 何叶芝 于 2020-05-27 设计创作,主要内容包括:本发明涉及石油化工技术领域,提供了一种分离原油沥青质次组分的方法。本发明通过逐步增加沉淀剂的比例,诱导沥青质次组分根据稳定性的不同从原油或沥青中逐步分离出来。相对于传统的先沉淀出来沥青质再分离沥青质次组分的方法,本发明的方法更接近真实地质情况,不存在沥青质先沉淀再溶解过程中可能出现的复杂的沥青质分子絮凝、吸附、沉淀、再溶解和解吸的过程,能更贴切地模拟真实的原油沥青质次序沉淀过程。本发明提供的方法能够模拟原油中不稳定沥青质次组分在地下逐步散失的过程,为石油生产中的沥青质危害问题和油气地球化学研究中的元素、同位素、特征化合物等变化研究提供帮助。(The invention relates to the technical field of petrochemical industry, and provides a method for separating crude oil asphaltene subcomponents. The invention induces the asphaltene subcomponents to be gradually separated from the crude oil or the asphalt according to the difference of the stability by gradually increasing the proportion of the precipitator. Compared with the traditional method for precipitating the asphaltene first and then separating the asphaltene subcomponents, the method provided by the invention is closer to the real geological condition, does not have the complicated processes of asphaltene molecule flocculation, adsorption, precipitation, redissolution and desorption which can occur in the process of precipitating the asphaltene first and then dissolving the asphaltene, and can more closely simulate the real sequential precipitation process of the crude oil asphaltene. The method provided by the invention can simulate the gradual dissipation process of unstable asphaltene subcomponents in crude oil in the underground, and provides help for asphaltene harm problems in petroleum production and change research of elements, isotopes, characteristic compounds and the like in oil gas geochemical research.)

1. A method for separating crude oil asphaltene subcomponents, comprising the steps of:

(1) determining the asphaltene precipitation point of the crude oil; the crude oil asphaltene precipitation point is the volume ratio of the lowest precipitator and the solvent which enable crude oil to precipitate;

(2) dissolving crude oil in a solvent, and adding a precipitating agent according to the volume ratio determined in the step (1) to obtain a precipitation system;

(3) oscillating the precipitation system to obtain an oscillating liquid;

(4) carrying out solid-liquid separation on the oscillation liquid, and collecting precipitates; the precipitate is an asphaltene subcomponent;

(5) adding a precipitator into the solution obtained in the step (4) through solid-liquid separation, so that the percentage of the precipitator in the total volume of the precipitator and the solvent is increased by 2-5%;

(6) repeating the steps (3) to (5) until the volume ratio of the precipitant to the solvent reaches 95: 5-99: 1, and respectively collecting precipitates and solutions obtained in the last step of solid-liquid separation;

(7) evaporating the solution collected in the step (6) to dryness, and collecting the residual crude oil components;

(8) adding a precipitant to the remaining crude oil component, and repeating steps (3) - (4) and (7).

2. The method of claim 1, wherein the method of determining the asphaltene precipitation point of the crude oil in step (1) comprises the steps of:

(a) dissolving crude oil in a solvent, wherein the volume ratio of a precipitator to the solvent is 20: adding a precipitator into the solution at a ratio of 80-30: 70 to obtain a precipitation system;

(b) carrying out solid-liquid separation after oscillating treatment on the precipitation system, observing whether precipitation is generated, if no precipitation is generated, increasing the volume fraction of the precipitator by 30%, and carrying out oscillating treatment and solid-liquid separation again;

(c) repeating the step (B) until precipitation occurs, recording the volume ratio of the precipitating agent to the solvent when the precipitation occurs as a volume ratio A, and recording the volume ratio of the precipitating agent to the solvent before the precipitation occurs as a volume ratio B;

(d) dissolving crude oil in a solvent, and adding a precipitator according to the proportion that the percentage of the precipitator in the specific volume ratio B is 5 percent more, so as to obtain a precipitation system;

(e) carrying out solid-liquid separation after oscillation treatment on the precipitation system, observing whether precipitation is generated, if no precipitation is generated, increasing the volume fraction of the precipitator by 5%, and carrying out oscillation treatment and solid-liquid separation again;

(f) and (e) repeating the step (e) until precipitation occurs, wherein the volume ratio of the precipitating agent to the solvent when the precipitation occurs is the asphaltene precipitation point of the crude oil.

3. The method according to claim 1 or 2, wherein the solvent comprises any one of dichloromethane, toluene, benzene and chloroform.

4. The method of claim 1 or 2, wherein the precipitation agent comprises any one of n-heptane, n-pentane, n-hexane, and acetone.

5. The method according to claim 1 or 2, wherein the time for the shaking treatment in the step (3), the step (b) and the step (e) is independently 8-48 h.

6. The process according to claim 1 or 2, wherein the solid-liquid separation in step (4), step (b) and step (e) is independently centrifugation or filtration.

7. The method of claim 6, wherein the rotational speed of the centrifugation is not less than 3500 rpm and the centrifugal force is not less than 1000 g.

8. The method according to claim 7, wherein the time for the centrifugation is 10min or more.

9. The method of claim 6, wherein the filtration membrane has a pore size of 0.45 μm.

10. The method of claim 1 or 2, wherein when the precipitant is n-heptane and the solvent is toluene, the volume ratio of precipitant to solvent at the asphaltene precipitation point of the crude oil is between 50:50 and 80: 20.

Technical Field

The invention relates to the technical field of petrochemical industry, in particular to a method for separating crude oil asphaltene subcomponents.

Background

Under the condition of changing the conditions of composition, temperature, pressure, etc. or under the action of geological stratification effect, the asphaltene in the crude oil may become unstable and precipitate, and the internal components of the asphaltene have different stabilities, so that the precipitation of the asphaltene occurs sequentially with the change of the conditions, and the more unstable part precipitates first. A considerable part of heteroatoms (comprising N, S, O, metals and the like) in petroleum exists in asphaltene, wherein metals such as Ni, V and the like have important significance for understanding the deposition environment of hydrocarbon source rocks, and radioactive element systems (such as U-Pb, Rb-Sr, Sm-Nd and Re-Os) have significance for determining the number of years of radioactive isotopes of crude oil and the like. The asphaltene inclusions may also contain biomarker compounds that are not destroyed by the later engineering process. Therefore, understanding the sequential precipitation of asphaltenes in crude oil is of great geological significance.

At present, the asphaltene is generally precipitated from the crude oil once by adding excessive n-alkane, and then the sub-components of the asphaltene are subdivided. Flocculation and coagulation processes that occur when asphaltenes settle from crude oil can change the properties of asphaltene molecules or aggregates, while the surrounding molecular environment when asphaltenes dissolve and re-settle is significantly different from that in crude oil.

Disclosure of Invention

In view of the above, the present invention provides a method for separating crude oil asphaltene subcomponents. The method provided by the invention induces the asphaltene subcomponents to be gradually separated from the crude oil or the asphalt according to different stabilities by changing the proportion of the precipitating agent and the solvent, and can more closely simulate the real sequential precipitation process of the crude oil asphaltene.

In order to achieve the above object, the present invention provides the following technical solutions:

a method for separating crude oil asphaltene subcomponents comprising the steps of:

(1) determining the asphaltene precipitation point of the crude oil; the crude oil asphaltene precipitation point is the volume ratio of the lowest precipitator and the solvent which enable crude oil to precipitate;

(2) dissolving crude oil in a solvent, and adding a precipitating agent according to the volume ratio determined in the step (1) to obtain a precipitation system;

(3) oscillating the precipitation system to obtain an oscillating liquid;

(4) carrying out solid-liquid separation on the oscillation liquid, and collecting precipitates; the precipitate is an asphaltene subcomponent;

(5) adding a precipitator into the solution obtained in the step (4) through solid-liquid separation, so that the percentage of the precipitator in the total volume of the precipitator and the solvent is increased by 2-5%;

(6) repeating the steps (3) to (5) until the volume ratio of the precipitant to the solvent reaches 95: 5-99: 1, and respectively collecting precipitates and solutions obtained in the last step of solid-liquid separation;

(7) evaporating the solution collected in the step (6) to dryness, and collecting the residual crude oil components;

(8) adding a precipitant to the remaining crude oil component, and repeating steps (3) - (4) and (7).

Preferably, the method for determining the asphaltene precipitation point of the crude oil in the step (1) comprises the following steps:

(a) dissolving crude oil in a solvent, wherein the volume ratio of a precipitator to the solvent is 20: adding a precipitator into the solution at a ratio of 80-30: 70 to obtain a precipitation system;

(b) carrying out solid-liquid separation after oscillating treatment on the precipitation system, observing whether precipitation is generated, if no precipitation is generated, increasing the volume fraction of the precipitator by 30%, and carrying out oscillating treatment and solid-liquid separation again;

(c) repeating the step (B) until precipitation occurs, recording the volume ratio of the precipitating agent to the solvent when the precipitation occurs as a volume ratio A, and recording the volume ratio of the precipitating agent to the solvent before the precipitation occurs as a volume ratio B;

(d) dissolving crude oil in a solvent, and adding a precipitator according to the proportion that the percentage of the precipitator in the specific volume ratio B is 5 percent more, so as to obtain a precipitation system;

(e) carrying out solid-liquid separation after oscillation treatment on the precipitation system, observing whether precipitation is generated, if no precipitation is generated, increasing the volume fraction of the precipitator by 5%, and carrying out oscillation treatment and solid-liquid separation again;

(f) and (e) repeating the step (e) until precipitation occurs, wherein the volume ratio of the precipitating agent to the solvent when the precipitation occurs is the asphaltene precipitation point of the crude oil.

Preferably, the solvent includes any one of dichloromethane, toluene, benzene and chloroform.

Preferably, the precipitant includes any one of n-heptane, n-pentane, n-hexane, and acetone.

Preferably, the time of the oscillation treatment in the step (3), the step (b) and the step (e) is 8-48 h independently.

Preferably, the solid-liquid separation method in the step (4), the step (b) and the step (e) is centrifugal separation or filtration independently.

Preferably, the rotation speed of the centrifugal separation is more than or equal to 3500 rpm, and the centrifugal force is more than or equal to 1000 g.

Preferably, the time for the centrifugal separation is 10min or more.

Preferably, the pore size of the filtration membrane is 0.45 μm.

Preferably, when the precipitant is n-heptane and the solvent is toluene, the volume ratio of precipitant to solvent at the asphaltene precipitation point of the crude oil is between 50:50 and 80: 20.

The invention provides a method for separating crude oil asphaltene subcomponents, which comprises the steps of dissolving crude oil in a solvent, adding a precipitator, and separating the asphaltene subcomponents through oscillation and solid-liquid separation. Compared with the traditional method for precipitating the asphaltene first and then separating the asphaltene subcomponents, the method provided by the invention is closer to the real geological condition, does not have the complicated processes of asphaltene molecule flocculation, adsorption, precipitation, redissolution and desorption which can occur in the process of precipitating the asphaltene first and then dissolving the asphaltene, and can more closely simulate the real sequential precipitation process of the crude oil asphaltene. The method provided by the invention can simulate the gradual dissipation process of unstable asphaltene subcomponents in crude oil in the underground, and provides help for asphaltene harm problems in petroleum production and change research of elements, isotopes, characteristic compounds and the like in oil gas geochemical research.

Detailed Description

The invention provides a method for separating crude oil asphaltene subcomponents, which comprises the following steps:

(1) determining the asphaltene precipitation point of the crude oil; the crude oil asphaltene precipitation point is the volume ratio of the lowest precipitator and the solvent which enable crude oil to precipitate;

(2) dissolving crude oil in a solvent, and adding a precipitating agent according to the volume ratio determined in the step (1) to obtain a precipitation system;

(3) oscillating the precipitation system to obtain an oscillating liquid;

(4) carrying out solid-liquid separation on the oscillation liquid, and collecting precipitates; the precipitate is an asphaltene subcomponent;

(5) adding a precipitator into the solution obtained by separation in the step (4), so that the percentage of the precipitator in the total volume of the precipitator and the solvent is increased by 2-5%;

(6) repeating the steps (3) to (5) until the volume ratio of the precipitant to the solvent reaches 95: 5-99: 1, and respectively collecting precipitates and solutions obtained in the last step of solid-liquid separation;

(7) evaporating the solution collected in the step (6) to dryness, and collecting the residual crude oil components;

(8) adding a precipitant to the remaining crude oil component, and repeating steps (3) - (4) and (7).

The invention first determines the asphaltene precipitation point of the crude oil. In the present invention, the precipitation point is the volume ratio of the lowest precipitant to the solvent that causes precipitation of crude oil asphaltenes; the method of determining the asphaltene precipitation point preferably comprises the steps of:

(a) dissolving crude oil in a solvent, wherein the volume ratio of a precipitator to the solvent is 20: adding a precipitator into the solution at a ratio of 80-30: 70 to obtain a precipitation system;

(b) carrying out solid-liquid separation after oscillating treatment on the precipitation system, observing whether precipitation is generated, if no precipitation is generated, increasing the volume fraction of the precipitator by 30%, and carrying out oscillating treatment and solid-liquid separation again;

(c) repeating the step (B) until precipitation occurs, recording the volume ratio of the precipitating agent to the solvent when the precipitation occurs as a volume ratio A, and recording the volume ratio of the precipitating agent to the solvent before the precipitation occurs as a volume ratio B;

(d) dissolving crude oil in a solvent, and adding a precipitator according to the proportion that the percentage of the precipitator in the solvent is 5 percent more than that in the solvent B by volume to obtain a precipitation system;

(e) carrying out solid-liquid separation on the obtained precipitation system after oscillation treatment, observing whether precipitation is generated, if no precipitation is generated, increasing the volume fraction of the precipitator by 5%, and carrying out oscillation treatment and solid-liquid separation again;

(f) and (e) repeating the step (e) until precipitation occurs, wherein the volume ratio of the precipitating agent to the solvent when the precipitation occurs is the asphaltene precipitation point of the crude oil.

The method comprises the steps of firstly dissolving crude oil into a solvent, and adding a precipitator into the solution according to the volume ratio of the precipitator to the solvent of 20: 80-30: 70 to obtain a precipitation system. In the present invention, the solvent preferably includes any one of dichloromethane, toluene, benzene and chloroform, more preferably toluene; the precipitant preferably comprises any one of n-heptane, n-pentane, n-hexane and acetone, more preferably n-heptane; the dosage ratio of the crude oil to the solvent can be flexibly set according to experiment purposes and crude oil properties, and is preferably 0.1-1 g: 1-10 mL, more preferably 1g: 1-10 mL, and still more preferably 1g:10 mL; in the present invention, the volume ratio of the precipitant to the solvent at the time of first addition of the precipitant is more preferably 20:80, 25:75 or 30:70, and still more preferably 20: 80.

After a precipitation system is obtained, the invention carries out solid-liquid separation after the precipitation system is oscillated. In the invention, the time of the oscillation treatment is preferably 8-48 h, and more preferably 16-32 h; the temperature of the oscillation treatment is room temperature, namely, no additional heating or cooling is needed; the room temperature is 20-25 ℃; the solid-liquid separation method is preferably centrifugal separation or filtration; the rotating speed of the centrifugal separation is preferably not less than 3500 revolutions per minute, more preferably 3500-4500 revolutions per minute, and the centrifugal force of the centrifugal separation is preferably not less than 1000g, more preferably 1000-2000 g; the time of centrifugal separation is preferably more than 10min, and more preferably 10-15 min; the aperture of the filter membrane for filtration is 0.45 μm.

And (3) observing whether precipitation is generated or not after solid-liquid separation, if no precipitation is generated, increasing the volume fraction of the precipitant by 30%, and performing oscillation treatment and solid-liquid separation again, if no precipitation is generated, repeating the steps of increasing the volume fraction of the precipitant (30% increase each time), oscillation treatment and solid-liquid separation until precipitation is generated, wherein the precipitation point of the asphaltene is positioned between the volume ratio of the precipitant to the solvent (recorded as volume ratio A) when precipitation is generated and the volume ratio of the precipitant to the solvent (recorded as volume ratio B) in the previous experiment. In particular embodiments of the present invention, experiments are preferably conducted with the volume ratios of precipitant to solvent selected from 20:80, 50:50 and 80: 20; in the embodiment of the present invention, it is preferable to simultaneously weigh three crude oils, simultaneously perform experiments in which the volume ratios of the precipitant and the solvent are 20:80, 50:50, and 80:20, and then observe whether or not precipitation occurs, so as to shorten the experiment time. In the embodiment of the invention, the volume ratio range of the precipitating agent and the solvent in which the crude oil asphaltene precipitation point is positioned can be determined according to the existing research, and then the subsequent operation is carried out according to the range.

In a particular embodiment of the invention, when the precipitant is n-heptane and the solvent is toluene, the volume ratio of precipitant to solvent at the asphaltene precipitation point for a substantial portion of the crude oil is between 50:50 and 80:20, particularly between 65:35 and 75: 25.

After the volume ratio range of the precipitant and the solvent at the asphaltene precipitation point of the crude oil is determined, the crude oil is dissolved in the solvent, and the precipitant is added according to the proportion that the percentage content of the precipitant in the specific volume ratio B is 5 percent more, so as to obtain a precipitation system; the dosage ratio of the crude oil to the solvent is preferably 0.1-1 g:1 to 10mL, more preferably 1g to 1 to 10mL, and still more preferably 1g to 10 mL.

After a precipitation system is obtained, the solid-liquid separation is carried out after the obtained precipitation system is subjected to oscillation treatment. In the present invention, the method of the oscillation treatment and the solid-liquid separation is the same as the above scheme, and is not described herein again.

After solid-liquid separation, observing whether a precipitate is generated, if no precipitate is generated, increasing the volume fraction of the precipitator by 5%, and performing oscillation treatment and solid-liquid separation again; if no precipitation is generated, the steps of increasing the volume fraction of the precipitator (the proportion of each increase is preferably 5%), oscillating and separating solid from liquid are repeated until precipitation occurs, and the volume ratio of the precipitator to the solvent when precipitation occurs is the precipitation point of the asphaltene.

In the specific embodiment of the present invention, preferably, the precipitation point is located in a volume ratio range, and the precipitation point is divided into a plurality of sets of experiments according to a proportion that the volume fraction of the precipitating agent is gradually increased by 5%, the plurality of sets of experiments are performed simultaneously, and the precipitation condition is observed to shorten the experiment time; for example, when the precipitation point is between 50:50 and 80:20 (both the volume ratio of the precipitant to the solvent), the present invention preferably weighs 6 parts of crude oil, and simultaneously performs experiments with the volume ratio of the precipitant to the solvent being 55:45, 60:40, 65:35, 70:30, 75:25, and 80:20, and observes the precipitation, and the lowest proportion of precipitation occurring is the precipitation point.

After determining the asphaltene precipitation point, the crude oil is dissolved in a solvent, and a precipitator is added according to the volume ratio of the precipitation point to obtain a precipitation system. In the present invention, the crude oil and the solvent are preferably used in a ratio of 1g: 1-10 mL, in the embodiment of the invention, the dosage of the crude oil is preferably more than 20g, so as to avoid that the precipitation is too small to be observed conveniently.

After a precipitation system is obtained, oscillating the precipitation system to obtain an oscillating liquid; the conditions of the oscillation process are consistent with the above scheme, and are not described in detail herein.

After the oscillation liquid is obtained, the invention carries out solid-liquid separation on the oscillation liquid and collects the precipitate. In the invention, the solid-liquid separation condition is consistent with the scheme, and the details are not repeated herein; the invention preferably collects the precipitate by using dichloromethane, namely, the precipitate is completely dissolved by using dichloromethane, and then the dichloromethane is evaporated to dryness, wherein the temperature for evaporating the dichloromethane to dryness is preferably 35 ℃; the collected precipitate is the asphaltene subcomponent.

After solid-liquid separation, adding a precipitator into the solution obtained by separation, so that the percentage of the precipitator in the total volume of the precipitator and the solvent is increased by 2-5%, preferably by 5%; and then repeating the steps of oscillating treatment, solid-liquid separation and increasing the percentage of the precipitating agent until the volume ratio of the precipitating agent to the solvent reaches 95: 5-99: 1 (namely the proportion of the precipitating agent is close to 100%), collecting precipitates obtained by solid-liquid separation each time during the period, wherein the precipitates are sequentially separated asphaltene subcomponents.

And after the solid-liquid separation in the last step is finished, collecting the obtained solution, and evaporating to dryness, wherein the evaporated matter is the residual crude oil component. The invention has no special requirements on the specific conditions of the evaporation to dryness, and can be fully evaporated to dryness.

After obtaining the residual crude oil component, the invention adds the precipitator into the residual crude oil component (namely the volume fraction of the precipitator is 100 percent), and repeats the steps of oscillating treatment, solid-liquid separation, collecting the precipitate and the solution and evaporating the solution to dryness. In the present invention, the amount ratio of the precipitant to the remaining crude oil components is 40 mL: 1g of a compound; the conditions of the oscillation treatment and the solid-liquid separation are consistent with the scheme, and are not described again; the precipitate obtained by solid-liquid separation is asphaltene component precipitated when the precipitant is 100%, and the solid substance obtained by solid-liquid separation after evaporation of the solution is undeposited (i.e. the part capable of being dissolved in the precipitant).

The method provided by the invention gradually increases the proportion of the precipitant, gradually separates the asphaltene subcomponents in the crude oil according to the sequence of stability from small to large, and the separated asphaltene components can be subjected to subsequent experiments according to requirements, and the invention is not particularly limited.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

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