Method for analyzing and testing thick oil components

Abstract

The invention relates to a method for analyzing and testing thick oil components, and belongs to oilfield chemistry. The method comprises the following steps: carrying out absorbance measurement on thickened oil to obtain first thickened oil absorbance; titrating the thickened oil; carrying out absorbance measurement on the heavy oil subjected to asphaltene precipitation to obtain second heavy oil absorbance; obtaining the asphaltene content in the thickened oil according to the first thickened oil absorbance and the second thickened oil absorbance; filtering the heavy oil subjected to asphaltene precipitation, and separating by adopting a micro-fluidic chip to obtain maltha; the maltha is introduced into the chromatographic column, and a to-be-washed chromatographic column is obtained; eluting the to-be-eluted chromatographic column to obtain a saturated component, an aromatic component and colloid; measuring the saturates, the aromatics and the colloids to obtain the contents of the saturates, the aromatics and the colloids, and completing analysis and testing; component analysis is carried out on the thickened oil by adopting a microfluidic technology, efficient detection and analysis of the asphaltene of the thickened oil are realized, the operation is simple, and various heavy glass containers are not needed.

Description

Technical Field

[0001] This application relates to the field of oilfield chemistry, and particularly to a method for analyzing and testing heavy oil components. Background Art

[0002] Among the remaining world oil resources, heavy oil accounts for about 70%. China is the fourth largest heavy oil resource country in the world, with proven geological reserves of heavy oil reaching 3.55 billion tons, presenting great exploitation potential. During the exploration, exploitation, and transportation of heavy oil, the detection of crude oil asphaltene plays a crucial role. However, the current oil and gas field faces key technical problems such as long detection cycle of heavy oil sample components, high testing and analysis costs, and low detection automation degree, which seriously restricts the development of heavy oil. Summary of the Invention

[0003] This application provides a method for analyzing and testing heavy oil components to improve the current problem of difficult analysis of heavy oil components.

[0004] This application provides a method for analyzing and testing heavy oil components, and the method includes:

[0005] Measure the absorbance of heavy oil to obtain the first heavy oil absorbance;

[0006] Titrate the heavy oil to precipitate the asphaltene in the heavy oil;

[0007] Measure the absorbance of the heavy oil after asphaltene precipitation to obtain the second heavy oil absorbance;

[0008] Obtain the asphaltene content in the heavy oil according to the first heavy oil absorbance and the second heavy oil absorbance;

[0009] Filter the heavy oil after asphaltene precipitation and separate it using a microfluidic chip to obtain maltene;

[0010] Pass the maltene into a chromatographic column to obtain a chromatographic column to be eluted;

[0011] Elute the chromatographic column to be eluted to obtain saturates, aromatics, and resins;

[0012] Measure the saturates, aromatics, and resins to obtain the contents of saturates, aromatics, and resins, and complete the analysis and testing.

[0013] As an optional implementation manner, the eluting the chromatographic column to be eluted to obtain saturates, aromatics, and resins includes:

[0014] Perform a first elution on the chromatographic column to be eluted to obtain saturates;

[0015] Perform a second elution on the chromatographic column to be eluted to obtain aromatics;

[0016] Perform a third elution on the chromatographic column to be eluted to obtain colloid.

[0017] As an alternative embodiment, the eluent for the first elution includes n-heptane; and / or

[0018] the eluent for the second elution includes toluene; and / or

[0019] the eluent for the third elution includes a mixed solution of toluene and ethanol.

[0020] As an alternative embodiment, the order of the elution is the first elution, the second elution, and the third elution in sequence.

[0021] As an alternative embodiment, the measurement of the saturates, aromatics, and colloid to obtain the contents of the saturates, aromatics, and colloid includes:

[0022] Perform a refractive index measurement on the saturates to obtain the saturates refractive index;

[0023] Obtain the content of the saturates according to the saturates refractive index;

[0024] Perform an absorbance test on the aromatics and colloid to obtain the aromatics absorbance and the colloid absorbance;

[0025] Obtain the contents of the aromatics and colloid according to the aromatics absorbance and the colloid absorbance.

[0026] As an alternative embodiment, the refractive index measurement is performed using an Abbe refractometer.

[0027] As an alternative embodiment, the absorbance test is performed using a spectrometer.

[0028] As an alternative embodiment, the titration uses a non-polar solvent.

[0029] As an alternative embodiment, the non-polar solvent includes n-heptane or pentane.

[0030] As an alternative embodiment, the chromatographic column is filled with a stationary phase.

[0031] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0032] The method provided by the embodiments of the present application takes advantage of the microfluidic technology, such as small sample requirement, high detection efficiency, and simple operation. The microfluidic chip is used to separate the titrated heavy oil. The deasphalted heavy oil flows through the chromatographic column to achieve the separation of saturates, aromatics, and resins. Then, the content of each component is detected by spectroscopy. The microfluidic technology is used to analyze the components of heavy oil, realizing the efficient detection and analysis of heavy oil asphaltenes with simple operation and without the need for various bulky glass containers. In addition, microfluidics can accurately control the flow rate and flow volume of the solvent to achieve the full mixing and efficient titration of heavy oil and solvent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application and, together with the specification, are used to explain the principles of the present application.

[0034] To more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a schematic flow chart of the method provided by the embodiments of the present application;

[0036] Figure 2 It is a schematic diagram of the operation process of the method provided by the embodiments of the present application;

[0037] Figure 3 It is a schematic diagram of the basic principle of heavy oil component separation provided by the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0039] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in the present application can be obtained through the market or can be prepared by existing methods.

[0040] Among the remaining oil resources in the world, heavy oil accounts for about 70%. China is the fourth largest heavy oil resource country in the world, with the proven geological reserves of heavy oil reaching 3.55 billion tons, showing great potential for exploitation. During the exploration, exploitation, and transportation of heavy oil, the detection of crude oil asphaltene plays a crucial role. However, the current oil and gas field faces key technical problems such as long detection cycle of heavy oil sample components, high testing and analysis costs, and low degree of detection automation, which seriously restricts the development of heavy oil.

[0041] The advantages of microfluidic technology, such as small sample requirements, high detection efficiency, and simple operation, can be applied in the heavy oil field, such as research on chemical additive screening, injection parameter optimization, and remaining oil occurrence state. In related technologies, for example, Chinese Patent Application CN202211619580.3 discloses a system for simulating steam channeling plugging and profile control in heavy oil reservoirs based on microfluidics, which includes two etched transparent dielectric sheets with pore structures for reflecting steam channeling dominant channels in the middle arranged on a heating device. The injection parts of the etched transparent dielectric sheets are connected with a steam generating device, an oil storage device, and a particle suspension storage device, and the other ends of the two are jointly connected to a first displacement device. The other end of the steam generating device is connected to a second displacement device. The oil outlet part of the etched transparent dielectric sheet is connected with a liquid production collection device and an image acquisition device is arranged above it. The image acquisition device and the heating device are electrically connected to a data acquisition and analysis device. This system enables experimenters to observe the plugging and profile control process of steam and plugging agent particles and the oil production effect after steam channeling in heavy oil reservoirs at the pore scale, further exploring the development potential after steam channeling in heavy oil reservoirs, and with higher simulation accuracy. This application also discloses a method for simulating steam channeling plugging and profile control in heavy oil reservoirs based on microfluidics; Chinese Patent Application CN201410642984.3 discloses a microscopic displacement experiment system for heavy oil thermal recovery, which includes an injection system, a model system, an output system, and an image acquisition and analysis system. The injection system has a power source to provide displacement hot fluid. The model system receives the displacement hot fluid provided by the injection system and applies and controls the circumferential pressure around the microscopic model with inert gas to conduct the displacement experiment of hot fluid on heavy oil. The output system receives the output liquid after the displacement experiment and maintains a certain back pressure. The image acquisition and analysis system dynamically observes and photographs the microscopic displacement process and conducts research on microscopic seepage characteristics and displacement mechanisms. This microscopic displacement experiment system for heavy oil thermal recovery makes the experimental process and experimental method more reliable by improving the heating and heat preservation performance and sealing performance of the experimental system and conducting back pressure control design, and can conduct microscopic displacement experiments for heavy oil thermal recovery.

[0042] The inventors found that as Figure 3 shown, Figure 3Schematic diagram of the basic principle of heavy oil component separation provided by the embodiments of the present application. Heavy oil is mainly composed of saturates, aromatics, resins, and asphaltenes, namely SARA components. Asphaltenes are complex polycyclic molecules with aliphatic side chains and heteroatoms such as nitrogen, oxygen, sulfur, and heavy metals (such as vanadium, nickel, and iron). They are the most polar and aromatic, and the heaviest components in heavy oil, and they can dissolve in aromatic solvents (such as toluene or xylene) but are insoluble in alkane solvents (such as n-heptane). Therefore, asphaltenes can be separated by differences in solubility. In addition, there are significant differences in the polarity of the four components of heavy oil. Asphaltenes have the strongest polarity, followed by resins, aromatics, and saturates. Therefore, other components can be separated by differences in polarity.

[0043] Microfluidic technology can also be applied to the analysis of heavy oil components. Combining with the current method for determining the four components of petroleum asphalt, the inventors intend to provide a method for analyzing heavy oil components to improve problems such as the need for a large amount of laboratory equipment and bulky glass containers, long test cycles, and high costs in current heavy oil component analysis.

[0044] The first step of this method is to analyze the asphaltene content. The heavy oil needs to be titrated with an excessive amount of non-polar solvent (such as n-heptane or pentane) to force the precipitation of asphaltenes, and then filtered and separated through a microfluidic chip. The visible spectra of the heavy oil before and after precipitation are measured by a spectrometer, and the difference in absorbance is related to the asphaltene content of the sample. During this process, when measuring the asphaltene content, a microfluidic chip and an automatic pump are used to provide the repeatability and reproducibility of absorbance. The second step is to analyze the contents of saturates, aromatics, and resins. Once the asphaltene content is determined, the deasphalted oil (maltenes) will come out of the microfluidic chip and flow into a small chromatographic column filled with a stationary phase. Then, it is eluted successively with n-heptane, toluene, and toluene-ethanol to separate saturates, aromatics, and resins. The refractive index of saturates is measured using an Abbe refractometer, and the absorbance of aromatics and resins is measured using a spectrometer. The refractive index of saturates is related to the mass fraction of the component. Similarly, the absorbance of aromatics and resins is also related to the mass fraction of the component. The specific process is as follows:

[0045] Figure 1 Schematic diagram of the flow of the method provided by the embodiments of the present application Figure 2 Schematic diagram of the operation process of the method provided by the embodiments of the present application, as Figure 1 shown, the embodiments of the present application provide a method for analyzing heavy oil components, and the method includes:

[0046] S1. Measure the absorbance of heavy oil to obtain the absorbance of the first heavy oil;

[0047] In some embodiments, the absorbance test is measured using a spectrometer.

[0048] S2. Titrate the heavy oil to precipitate asphaltenes in the heavy oil;

[0049] In some embodiments, the titration uses a non-polar solvent. Further, the non-polar solvent includes n-heptane or pentane.

[0050] S3. Measure the absorbance of the heavy oil after asphaltene precipitation to obtain the absorbance of the second heavy oil;

[0051] S4. Obtain the asphaltene content in the heavy oil based on the absorbance of the first heavy oil and the absorbance of the second heavy oil;

[0052] S5. Filter the heavy oil after asphaltene precipitation and separate it using a microfluidic chip to obtain maltene;

[0053] In some embodiments, the microfluidic chip is a device that includes pore throats of different diameters. When crude oil flows through the chip, the chip enables different components of the crude oil to pass through pore throats of different diameters for preliminary separation. The chip has channels with different pore throat diameters to achieve separation of components such as asphaltenes and resins.

[0054] S6. Pass the maltene into a chromatographic column to obtain a chromatographic column to be eluted;

[0055] In some embodiments, the chromatographic column is filled with a stationary phase.

[0056] S7. Elute the chromatographic column to be eluted to obtain saturates, aromatics, and resins;

[0057] In some embodiments, eluting the chromatographic column to be eluted to obtain saturates, aromatics, and resins includes:

[0058] S7.1. Perform a first elution on the chromatographic column to be eluted to obtain saturates;

[0059] S7.2. Perform a second elution on the chromatographic column to be eluted to obtain aromatics;

[0060] S7.3. Perform a third elution on the chromatographic column to be eluted to obtain resins.

[0061] Further, the order of the elution is the first elution, the second elution, and the third elution in sequence. The eluent for the first elution includes n-heptane; the eluent for the second elution includes toluene; the eluent for the third elution includes a mixture of toluene and ethanol.

[0062] S8. Measure the saturates, aromatics, and resins to obtain the contents of saturates, aromatics, and resins, and complete the analysis and testing.

[0063] In some embodiments, the measuring of the saturates, aromas and gums to obtain the contents of the saturates, aromas and gums comprises:

[0064] S8.1. Measuring the refractive index of the saturated fraction to obtain the refractive index of the saturated fraction;

[0065] In some embodiments, the refractive index is measured using an Abbe refractometer.

[0066] S8.2. According to the saturated refractive index, the saturated content is obtained;

[0067] S8.3. The aroma points and colloids are subjected to absorbance tests to obtain the aroma points and colloid absorbance;

[0068] In some embodiments, the absorbance test is measured using a spectrometer.

[0069] S8.4. Obtain the contents of aroma and colloid based on the absorbance of the aroma and colloid.

[0070] This method takes advantage of the advantages of microfluidics technology, such as small sample requirements, high detection efficiency, and simple operation. It uses microfluidics chips to separate the titrated heavy oil. The deasphalted heavy oil flows through the chromatographic column to separate the saturated fraction, aromatic fraction, and colloid. The content of each component is then detected by spectroscopy. Microfluidics technology is used to analyze the components of the heavy oil, achieving efficient detection and analysis of heavy oil asphaltene, simple operation, and no need for various bulky glass containers. In addition, microfluidics can accurately control the flow rate and flow rate of the solvent, achieving full mixing and efficient titration of the heavy oil and the solvent.

[0071] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0072] Example 1

[0073] Taking the crude oil sample of Block X of Yangsanmu Oilfield in Dagang as an example, the four components of heavy oil were analyzed using the microfluidic chip provided by this application, and the four components of heavy oil were determined as shown in the following table:

[0074] Comparative Example 1

[0075] The crude oil samples in Block X of Yangsanmu Oilfield in Dagang were measured by the traditional four-component measurement method, and the process is as follows: (1) dehydrate the samples; (2) measure the asphaltene content according to the industry standard; (3) dilute the deasphalted samples with petroleum ether; (4) pre-wet the adsorption column at a constant temperature; (5) add alumina covering; (6) based on the refractive index measurement of the distillate and the ultraviolet-visible light analysis to make the distillation curve; (7) heat and dry for weighing; (8) calculate their respective contents.

[0076] The test results of Example 1 and Comparative Example 1 are shown in the following table:

[0077]

[0078] As can be seen from the above table, using the method provided in the embodiments of the present application to detect heavy oil can achieve relatively accurate measurement in a relatively short time.

[0079] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0080] In this application, unless otherwise specified, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the attached drawings. Additionally, in the description of this application's specification, terms such as "include" and "comprise" mean "include but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this text, "and / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B can be singular or plural. In this text, "at least one" means one or more, and "multiple" means two or more. "At least one kind", "at least one item (or one) of the following" or similar expressions refer to any combination of these items, including any combination of single item (or one) or plural items (or ones). For example, "at least one item (or one) of a, b, or c", or, "at least one item (or one) of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0081] The above description is only the specific implementation manners of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for analyzing and testing heavy oil components, characterized in that, the method includes: Measuring the absorbance of heavy oil to obtain the first heavy oil absorbance; Titrating the heavy oil to precipitate asphaltene in the heavy oil; Measuring the absorbance of the heavy oil after asphaltene precipitation to obtain the second heavy oil absorbance; Obtaining the asphaltene content in the heavy oil according to the first heavy oil absorbance and the second heavy oil absorbance; Filtering the heavy oil after asphaltene precipitation and separating it using a microfluidic chip to obtain maltene; Feeding the maltene into a chromatographic column to obtain a chromatographic column to be eluted; Eluting the chromatographic column to be eluted to obtain saturates, aromatics and resins; Measuring the saturates, aromatics and resins to obtain the contents of saturates, aromatics and resins, and completing the analysis and testing.

2. The method for analyzing and testing heavy oil components according to claim 1, characterized in that, the eluting the chromatographic column to be eluted to obtain saturates, aromatics and resins includes: Performing a first elution on the chromatographic column to be eluted to obtain saturates; Performing a second elution on the chromatographic column to be eluted to obtain aromatics; Performing a third elution on the chromatographic column to be eluted to obtain resins.

3. The method for analyzing and testing heavy oil components according to claim 2, characterized in that, the eluent for the first elution includes n-heptane; and / or the eluent for the second elution includes toluene; and / or the eluent for the third elution includes a mixed solution of toluene and ethanol.

4. The method for analyzing and testing heavy oil components according to claim 2, characterized in that, the order of elution is the first elution, the second elution and the third elution in sequence.

5. The method for analyzing and testing heavy oil components according to claim 1, characterized in that, the measuring the saturates, aromatics and resins to obtain the contents of saturates, aromatics and resins includes: Measuring the refractive index of the saturates to obtain the saturates refractive index; Obtaining the content of saturates according to the saturates refractive index; Performing an absorbance test on the aromatics and resins to obtain the aromatics absorbance and the resins absorbance; Obtaining the contents of aromatics and resins according to the aromatics absorbance and the resins absorbance.

6. The method for analyzing and testing heavy oil components according to claim 5, characterized in that, the refractive index measurement is performed using an Abbe refractometer.

7. The method for analyzing and testing heavy oil components according to claim 5, characterized in that, the absorbance test is performed using a spectrometer.

8. The method for analyzing and testing heavy oil components according to claim 1, characterized in that, the titration uses a non-polar solvent.

9. The method for analyzing and testing heavy oil components according to claim 8, characterized in that, the non-polar solvent includes n-heptane or pentane.

10. The method for analyzing and testing heavy oil components according to claim 1, characterized in that, the chromatographic column is filled with a stationary phase.

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