A single-stage oil inclusion composition analysis method based on crude oil inclusion body

Abstract

The present application belongs to the technical field of petroleum geological exploration and analysis, and particularly relates to a single-period oil inclusion composition analysis method based on crude oil inclusions. The present application combines fluorescence microscopic observation and quantitative fluorescence analysis methods, can accurately determine the diameter of oil inclusions, determine the appropriate grinding mesh, and identify the period of oil inclusions in the microscopic observation stage, and provides clear basis for the subsequent experimental process. The analysis of the present application covers the differential processing method of oil inclusions in calcite and quartz minerals, can efficiently and completely perform group composition pretreatment on oil inclusion-containing particles, is convenient to operate, has good reproducibility, and provides reliable technical support for revealing the oil and gas charging history and restoring the reservoir forming process. The present application adopts a crushing device equipped with a low-cost, large-capacity closed zirconium oxide grinding tank, realizes synchronous crushing of multiple samples on the basis of optimizing experimental equipment, and significantly improves the sample processing flux and experimental efficiency.

Description

Technical Field

[0001] This invention belongs to the field of petroleum geological exploration and analysis technology, specifically relating to a single-phase oil inclusion composition analysis method based on crude oil inclusions. Background Technology

[0002] Fluid inclusions are cavities filled with fluid within minerals, often considered "time capsules." Due to multiple phases of secondary hydrocarbon expulsion from source rocks and repeated activation of the transport system, reservoir rocks have undergone multiple phases of hydrocarbon charging. The maturity and properties of hydrocarbons in each phase differ, leading to a lack of clarity regarding the formation and modification processes. Analyzing the hydrocarbon composition in single-phase crude oil fluid inclusions can reveal information about the crude oil source and parent material, the history of hydrocarbon charging and the division of formation phases, and the evolution and modification effects of fluids within the reservoir.

[0003] Currently, in the field of oil inclusion composition analysis, most studies still rely primarily on the analysis of free hydrocarbons in reservoirs. This type of analysis can be divided into two approaches: single oil inclusion composition analysis and group oil inclusion composition analysis. Before conducting the analysis, it is usually necessary to remove hydrocarbon components adsorbed on the surface of mineral particles, and then open the oil inclusions enclosed in the mineral particles using physical or chemical methods to release and collect the contained hydrocarbon components. Currently, the composition analysis of single oil inclusions often uses laser ablation or vacuum detonation to achieve in-situ, micro-area sampling of hydrocarbon substances; while the composition analysis of group oil inclusions mostly uses mechanical crushing of rock particles or acid hydrolysis to achieve batch extraction of components.

[0004] In existing technologies, the conventional sample preparation process for analyzing the composition of group oil inclusions mainly includes steps such as sample crushing, mineral selection, cleaning, grinding (or acid hydrolysis), and extraction. First, the rock sample is crushed and cleaned to remove hydrocarbon residues adsorbed on the mineral surface. Then, the mineral particles are decomposed through mechanical grinding or acid dissolution, thereby releasing the hydrocarbon components contained in the group oil inclusions. Finally, the hydrocarbon components are collected through extraction. Patent CN115839908 A (Patent Title: A Method for Analyzing the Composition of Group Oil Inclusions in Calcite Minerals) uses "mechanical crushing + extraction" to release oil inclusion components from calcite microcracks, and then uses "acid dissolution + extraction" to release mineral matrix oil inclusion components, enabling the batch extraction of group oil inclusions with different properties from mineral microcracks and the mineral matrix for research.

[0005] However, the above process has the following problems: First, due to the lack of a systematic mineral selection process, the overall operation is cumbersome and the processing cycle is long. Furthermore, traditional crushing equipment has limited throughput, and for samples with low oil inclusion abundance, current technology is inefficient in screening, often resulting in insufficient extracts to support effective analysis and making it difficult to obtain reliable detection results. Second, the stainless steel material used in commonly used grinding equipment may release carbonaceous compounds during high-speed grinding, contaminating hydrocarbon components within the oil inclusions and distorting the final component analysis results. In addition, acid hydrolysis is only applicable to calcite minerals and is difficult to apply to the effective extraction and analysis of oil inclusions in quartz minerals in clastic rocks.

[0006] In view of the above analysis of the current state of technology, it is necessary to provide a single-stage oil inclusion composition analysis method based on the fluorescence spectrum of crude oil inclusions, which can effectively solve the problems of low efficiency, easy contamination and limited applicability in the existing technology. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a single-phase oil inclusion composition analysis method based on crude oil inclusions. This method uses fluorescence observation to screen samples with high oil inclusion content and belonging to a single phase, and employs a crushing device equipped with a low-cost, large-capacity, sealed zirconia grinding jar. Based on optimized experimental equipment, it achieves simultaneous crushing of multiple samples, minimizing external contamination. This method enables efficient and complete pretreatment of the group composition of oil-containing inclusion particles, significantly improving sample throughput and experimental efficiency. The technical solution adopted is as follows:

[0008] A method for single-phase oil inclusion composition analysis based on crude oil inclusions includes the following steps:

[0009] (1) Collect rock samples and prepare fluid inclusion slides;

[0010] (2) Select rock samples that meet the requirements by fluorescence microscopy and quantitative fluorescence analysis;

[0011] (3) The grinding mesh number was determined based on the maximum diameter of the oil inclusions obtained by fluorescence microscopy and quantitative fluorescence analysis, and the selected rock samples were ground.

[0012] (4) The rock samples after grinding are cleaned and dehydrogenated to completely remove hydrocarbon residues adhering to the surface of the particles;

[0013] (5) The rock sample with the hydrocarbon residues on the surface completely removed was subjected to short-term crushing in stages. A crushing device equipped with zirconium oxide crushing balls was used for crushing. Solvent was added to the crushing device for crushing while the mineral particles were soaked to dissolve the mineral particles in the solvent.

[0014] (6) After dissolving, transfer all the fine mineral fragments in the crushing device to a beaker; treat the solution in the beaker with ultrasound and let it stand; filter the supernatant containing the fluid inclusion extract and suspended mineral fragments through a filter membrane, and pass the filtrate into a round-bottom flask.

[0015] (7) The filtrate containing the fluid inclusion extract was concentrated; the round-bottom flask containing the filtrate was placed in a rotary evaporator for initial concentration, and then further concentrated by purging with high-purity nitrogen.

[0016] (8) The concentrated solution was analyzed by gas chromatography-mass spectrometry to determine the composition of the oil inclusions.

[0017] Preferably, in step (2), when selecting carbonate rock samples, rock samples with well-developed cement, abundant veins, and large calcite mineral grains are selected, and it is necessary to confirm that the matrix does not contain secondary fluid inclusions; if the conditions are met, the rock samples are included in the experimental scope; for clastic rock samples, rock samples with low mud content and granular support structure are selected.

[0018] By combining fluorescence microscopy and quantitative fluorescence analysis, the particle size of oil inclusions was accurately determined, and samples containing only single-phase oil inclusions were screened out.

[0019] Preferably, in step (3), the grinding mesh size is smaller than the maximum diameter of the observed oil inclusions.

[0020] Preferably, in step (4), the specific cleaning process is differentiated according to the mineral type as follows: For calcite minerals, ultrasonic cleaning is performed sequentially using methanol, a mixed solution of dichloromethane and methanol, and dichloromethane; each reagent is used to clean 2 to 3 times, and each cleaning time is 10 to 15 minutes, to ensure that the hydrocarbon substances on the surface of the mineral particles are completely removed.

[0021] For quartz minerals, firstly, ultrasonic cleaning with 10% hydrogen peroxide for 10-15 minutes is performed to remove organic matter between mineral particles; then, ultrasonic cleaning with 5% dilute hydrochloric acid for 10-15 minutes is performed to dissolve and remove carbonate minerals; next, the sample is placed in boiling aqua regia and reacted for 5-10 minutes to thoroughly remove sulfides and iron and manganese oxides; the sample is repeatedly rinsed with distilled water until the aqua regia is completely removed, and then dried; then, ultrasonic cleaning is performed sequentially with methanol, a mixture of dichloromethane and methanol, and dichloromethane, with each reagent used 2-3 times, 10-15 minutes each time, to ensure that residual hydrocarbons on the surface of the mineral particles are completely removed.

[0022] Preferably, the volume ratio of dichloromethane to methanol in the mixed solution is 93:7.

[0023] Preferably, the method to confirm that the residual hydrocarbons on the surface of the mineral particles have been completely removed is as follows: take the last cleaning solution as the sample to be tested and perform gas chromatography-mass spectrometry analysis to detect whether it contains residual hydrocarbons; if residual hydrocarbons are detected, the cleaning operation in step (4) needs to be repeated; if not detected, it indicates that the hydrocarbons have been completely removed.

[0024] Preferably, in step (5), an XQM series planetary ball mill is used as the crushing device. The crushing device includes at least one crushing jar, and may have two, three, or up to four crushing jars. Multiple crushing jars can be accommodated at the same time to complete the crushing operation of multiple samples in parallel. Each crushing jar includes three different diameter zirconia crushing balls of 4 mm, 8 mm, and 10 mm. The total volume of the sample and the crushing balls accounts for one-third of the volume of the crushing jar.

[0025] Preferably, in step (5), after adding dichloromethane, the instrument parameters are set to 5 minutes for each crushing time, 3 crushing times in total, and 10 minutes between adjacent crushing times.

[0026] Preferably, in step (6), the solvent is dichloromethane; after opening the crushing device, pour the suspension containing fine mineral fragments into a beaker, and also gently pour the zirconia crushing balls into the beaker; then add dichloromethane to the crushing tank and soak for 2 hours, then transfer the soaked solution to the beaker, repeat the operation until all the extracts and mineral fragments in the crushing tank are transferred to the beaker; perform ultrasonic treatment on the solution in the beaker for 15 minutes, and let it stand for 5 minutes.

[0027] Preferably, in step (7), during concentration, the round-bottom flask containing the filtrate is placed in a rotary evaporator for initial concentration, and then further concentrated by purging with high-purity nitrogen gas, i.e., re-concentration.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] (1) This invention proposes a method that combines fluorescence microscopy and quantitative fluorescence analysis, which can accurately determine the diameter of oil inclusions, determine the appropriate grinding mesh and identify the oil inclusion phase during the microscopic observation stage, providing a clear basis for subsequent experimental procedures and significantly improving experimental efficiency;

[0030] (2) This invention provides a systematic experimental procedure for single-phase oil inclusion composition analysis, covering differentiated treatment methods for oil inclusions in calcite and quartz minerals. It can efficiently and completely pre-treat the group composition of oil inclusion particles. It is convenient to operate and has good reproducibility, providing reliable technical support for revealing the history of oil and gas charging and restoring the process of hydrocarbon accumulation.

[0031] (3) The XQM planetary ball mill used in this invention has a crushing tank and crushing balls made of zirconium oxide. During high-speed crushing, it can effectively avoid contamination of hydrocarbon samples by the release of carbon compounds from the metal material, thereby ensuring the authenticity and accuracy of the analysis results. In addition, the device supports crushing up to four samples at the same time, which significantly improves the sample processing throughput and experimental efficiency. Attached Figure Description

[0032] Figure 1 This is a roadmap for single-stage oil inclusion composition analysis based on crude oil inclusions, as described in Embodiment 1 of the present invention.

[0033] Figure 2 These are scanning electron microscope images of fluid inclusions in Application Examples 1(a) and 2(b) of the present invention.

[0034] Figure 3 These are photomicrographs of a rock sample from Application Example 1 of the present invention, taken under single polarized light (a) and microscopic fluorescence observation (b) modes.

[0035] Figure 4 This is a microfluorescence spectrum histogram of a thin section of fluid inclusions in a rock sample from Application Example 1 of the present invention.

[0036] Figure 5 These are photomicrographs of a rock sample from Application Example 2 of the present invention, taken under single polarized light (a) and microscopic fluorescence observation (b) modes.

[0037] Figure 6 This is a microfluorescence spectrum histogram of a thin section of fluid inclusions in a rock sample from Application Example 2 of the present invention.

[0038] Figure 7 This is a gas chromatography-mass spectrometry (GC-MS) analysis spectrum of the cleaning solution in Application Example 1 of this invention.

[0039] Figure 8 The chromatographic mass spectrum of the concentrated solution in Example 1 of this invention is shown.

[0040] Figure 9 This is a gas chromatography-mass spectrometry (GC-MS) analysis spectrum of the cleaning solution in Application Example 2 of the present invention.

[0041] Figure 10 The chromatographic mass spectrum of the concentrated solution in Example 2 of this invention is shown. Detailed Implementation

[0042] The accompanying drawings are for illustrative purposes only; to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with the accompanying drawings and embodiments of the present invention.

[0043] It should be done immediately. Existing technologies and common knowledge may be omitted. Unless otherwise specified, the testing instruments, methods, and materials used can be purchased or obtained through conventional methods.

[0044] Example 1, as Figure 1 As shown, a single-period oil inclusion composition analysis method based on crude oil inclusions is proposed.

[0045] This analytical method employs the following steps:

[0046] Step 1: Collect rock samples and prepare thin sections of inclusions.

[0047] Preliminary screening can be carried out during the rock sample collection stage: for carbonate rocks, samples with well-developed veins should be selected first; for clastic rocks, samples with lower clay content should be selected.

[0048] Step Two: In the reservoir fluid inclusion observation and quantitative fluorescence determination experiment, for carbonate rock samples, rock samples with well-developed cement, abundant veins, and large calcite mineral grains should be preferred. Microscopic confirmation is also needed to identify the presence of multiple oil inclusions in the matrix. If these conditions are met, such samples can be included in the experimental scope. For clastic rock samples, rock samples with low clay content and granular support structures are preferred. Furthermore, fluorescence microscopy and quantitative fluorescence analysis techniques should be combined to accurately determine the grain size of the oil inclusions and screen samples containing only single-stage oil inclusions for subsequent experiments.

[0049] Step 3: Grind the selected qualified samples. The specific mesh size needs to be determined based on the maximum diameter of the oil inclusions obtained through microscopic observation in Step 2.

[0050] Step 4: Clean and remove hydrocarbon residues from the sample ground in Step 3 to thoroughly remove hydrocarbon residues adhering to the particle surface. The specific cleaning process varies depending on the mineral type, as follows:

[0051] For calcite minerals, ultrasonic cleaning was performed sequentially using a mixture of methanol, dichloromethane, and methanol (volume ratio 93:7), and then dichloromethane. Each reagent was used three times, with each cleaning session lasting 15 minutes, to ensure that hydrocarbons on the surface of the mineral particles were completely removed.

[0052] For quartz minerals, the first step was to use 10% hydrogen peroxide for ultrasonic cleaning for 15 minutes to remove organic matter between mineral particles. Then, 5% dilute hydrochloric acid was used for ultrasonic cleaning for 15 minutes to dissolve and remove carbonate minerals. The sample was then placed in boiling aqua regia and reacted for 10 minutes to thoroughly remove sulfides and iron and manganese oxides. The sample was repeatedly rinsed with distilled water until the aqua regia was completely removed, followed by drying. Then, the sample was ultrasonically cleaned step by step with a mixture of methanol, dichloromethane and methanol (volume ratio of 93:7), and dichloromethane. Each reagent was used three times for 15 minutes each time to ensure that residual hydrocarbons on the surface of the mineral particles were completely removed.

[0053] Take the final cleaning solution from step four as the sample to be tested and perform gas chromatography-mass spectrometry (GC-MS) analysis to detect whether it contains residual hydrocarbons. If residual hydrocarbons are detected, the cleaning operation in step four needs to be repeated; if not detected, proceed to step five.

[0054] Step 5: Perform short-duration crushing on the oil-washed sample. This method uses an XQM series planetary ball mill as the crushing device. This equipment is equipped with a zirconia crushing jar and various sizes of zirconia crushing balls, with diameters of 4 mm, 8 mm, and 10 mm. The ball mill can accommodate four crushing jars simultaneously, completing the crushing operation of four samples in parallel. The sample is placed in the zirconia crushing jar, and three different diameter zirconia crushing balls are added, so that the total volume of the sample and crushing balls occupies one-third of the crushing jar's volume. Using crushing balls of multiple sizes helps to achieve a more thorough grinding effect. After adding dichloromethane, the instrument parameters are set to a crushing time of 5 minutes per crushing cycle, a total of 3 crushing cycles, and a 10-minute interval between adjacent crushing cycles, in order to minimize the evaporation loss of oil in the fluid inclusions. This crushing process aims to release the oil inclusions within the mineral particles through physical crushing and dissolve them in dichloromethane.

[0055] Step Six: Filter to obtain a clear solution. After opening the crushing vessel, pour the suspension containing fine mineral fragments into a beaker, and gently add the zirconia fragments to the beaker as well. Add dichloromethane to the crushing vessel and soak for 2 hours. Transfer the soaking solution to the beaker as well. Repeat the process until all the extract and mineral fragments in the crushing vessel are transferred to the beaker. Sonicate the solution in the beaker for 15 minutes, then let it stand for 5 minutes. Filter the supernatant containing the fluid inclusion extract and suspended mineral fragments through a filter membrane, and pass the filtrate into a round-bottom flask.

[0056] Step 7: Concentrate the obtained solution containing the fluid inclusion extract. Place the round-bottom flask containing the filtrate in a rotary evaporator for initial concentration, followed by further concentration using high-purity nitrogen purging.

[0057] Step 8: Perform gas chromatography-mass spectrometry (GC-MS) analysis on the concentrated solution to determine the composition of the oil inclusions.

[0058] Application Example 1: This example uses a carbonate core sample from the Ordovician reservoir of well LG351 in the Lunnan area of ​​the Tarim Basin to conduct a single-stage oil inclusion composition analysis based on the fluorescence spectrum of crude oil inclusions.

[0059] The specific steps are as follows:

[0060] (1) During the preparation of thin sections, samples with well-developed calcite veins were selected and fluid inclusion thin sections were prepared, see [reference needed]. Figure 2 As shown in Figure (a);

[0061] (2) First, a thin-section scanning photograph of the fluid inclusions was taken, revealing well-developed calcite veins in the central region. Subsequently, fluorescence observation and quantitative fluorescence measurement were performed under a biological microscope. For example... Figure 3 As shown, the observation and measurement results indicate that the blue fluorescent oil inclusions in this application example are from a single-phase filling, and the abundance of oil inclusions is high. Only a small amount of sample needs to be broken to meet the test concentration requirements, which helps to save sample volume. Figure 4 As shown, fluorescence analysis revealed that the main peak wavelength was located in the range of 470-480 nm, which is consistent with... Figure 3 The blue fluorescence observed in (b) corroborates each other. Microscopic measurements showed that the diameters of the oil inclusions were all less than 100 μm, with the vast majority less than 40 μm, thus determining the grinding mesh to be 80 mesh. Approximately 10 g of sample was weighed and ground, then washed with purified water and dried.

[0062] (3) Place the dried sample in a 250 mL beaker, add 40 mL of methanol solution, and wash in an ultrasonic water bath for 15 minutes. Repeat this operation three times. Then add 40 mL of a mixed solution of dichloromethane (analytical grade, redistilled) and methanol (volume ratio 93:7), and wash in an ultrasonic bath for 15 minutes, repeating this operation three times. Finally, add 40 mL of dichloromethane (analytical grade, redistilled), and wash in an ultrasonic bath for 15 minutes, repeating this operation three times. Collect the final washing solution, concentrate it to 1 mL, transfer it to a chromatographic injection bottle, and analyze it by GC-MS to obtain the mass chromatogram. See figure below. Figure 7 As shown in the figure, there are no obvious chromatographic peaks. The spectral results indicate that there are no hydrocarbon residues on the surface of the mineral particles, meeting the requirements for fragmentation. The GC-MS instrument used in this embodiment is a triple quadrupole gas chromatography-mass spectrometry system. Compared with a single quadrupole mass spectrometer, it has higher compound discrimination ability and detection sensitivity for low-concentration samples, and is more suitable for the detection of crude oil components in inclusions.

[0063] (4) Place the washed oil sample into the zirconia crushing jar, add three different diameter zirconia crushing balls, so that the total volume of the sample and crushing balls occupies one-third of the crushing jar's volume, and then add 40 mL of dichloromethane (analytical grade, redistilled). Place the rubber ring at the jar opening and seal the crushing jar, then use a double nut clamp to tighten the crushing jar to prevent it from detaching during high-speed rotation. After setting the instrument parameters, start the crushing program.

[0064] The ball mill used in this invention can process up to four samples simultaneously and must maintain diagonal balance to ensure stable operation; therefore, an odd number of samples cannot be crushed. The crushing parameters are set as follows: each crushing session lasts 5 minutes, for a total of 3 crushing sessions, with a 10-minute interval between adjacent sessions, to minimize the evaporation loss of oil in the fluid inclusions.

[0065] (5) After crushing, carefully transfer the suspension containing mineral fragments and the crushed pellets from the crushing vessel to a 250 mL beaker. Add 40 mL of dichloromethane to the crushing vessel and soak for 2 hours. Transfer the resulting soaking solution to the same beaker. Repeat this soaking operation twice to ensure that all mineral fragments and extracts in the crushing vessel are fully recovered. Then, place the beaker in an ultrasonic water bath for 15 minutes and let it stand for 5 minutes. Finally, filter the supernatant containing the fluid inclusion extract and suspended fragments through a filter membrane and collect the filtrate in a round-bottom flask.

[0066] (6) The filtrate in the round-bottom flask was concentrated using a rotary evaporator, and then further concentrated to 1 mL by purging with high-purity nitrogen. The resulting concentrate was analyzed by gas chromatography-mass spectrometry (GC-MS), and the results are as follows: Figure 8 As shown, the experimental results demonstrate that this method successfully achieved the extraction of large quantities of crude oil from inclusions. The obtained spectra did not exhibit obvious unresolved complex mixture (UCM) peak groups, confirming that the crude oil had not undergone significant biodegradation. Analysis showed that the main peak of the crude oil had a carbon number of C20, indicating a high level of maturity, higher than that of the sample in Application Example 2. This maturity characteristic is corroborated by the observed wavelength and color of the main fluorescence peak.

[0067] Application Example 2: This example uses clastic rock samples from the Carboniferous reservoir of well LG8 in the Lunnan area of ​​the Tarim Basin to conduct single-stage oil inclusion composition analysis based on crude oil inclusion fluorescence spectroscopy.

[0068] The specific steps are as follows:

[0069] (1) When making thin sections, pure sandstone (without clay components) samples were selected to make fluid inclusion thin sections;

[0070] (2) First, scanned images of the fluid inclusions were taken, such as... Figure 2As shown in (b), the thin section is predominantly supported by granules, with less support from heterostructures. Subsequently, fluorescence observation and quantitative fluorescence measurement were performed under a biological microscope. Figure 5 , 6 As shown, the observation and measurement results indicate that the main fluorescence peak wavelength is located at 530-540 nm, which is consistent with... Figure 5 The yellow-green fluorescence observed in (b) corroborates each other, indicating that this application example involves a single-phase filling of yellow-green fluorescent oil inclusions. Furthermore, the oil inclusion abundance is high, requiring only a small amount of sample to achieve the required concentration, thus conserving sample. Microscopic measurements show that the oil inclusion diameters are all less than 100 μm, with the vast majority less than 40 μm, thus determining the grinding mesh to be 80 mesh. Approximately 13 g of sample was weighed and ground, then washed with purified water and subsequently dried.

[0071] (3) Place the dried sample in a 250 mL beaker and perform the following cleaning treatments in sequence: First, add 50 mL of 10% hydrogen peroxide and react in an ultrasonic water bath for 15 minutes to remove organic matter between mineral particles; then add 50 mL of 5% dilute hydrochloric acid and react in an ultrasonic water bath for 15 minutes to completely remove carbonate minerals; then add 50 mL of aqua regia, place the beaker on a heating platform and heat to boiling and maintain for 10 minutes to remove all sulfides and iron and manganese oxides. After cooling, wash repeatedly with distilled water until the aqua regia is completely removed, and then dry. Add 40 mL of methanol solution to the dried sample and wash in an ultrasonic water bath for 15 minutes, repeating the operation three times; then add 40 mL of a mixed solution of dichloromethane (analytical grade, redistilled) and methanol (volume ratio 93:7), and ultrasonically wash for 15 minutes, repeating the operation three times; finally, add 40 mL of dichloromethane (analytical grade, redistilled), and ultrasonically wash for 15 minutes, repeating the operation three times. The final washing solution was collected, concentrated to 1 mL, transferred to a chromatographic sample vial, and analyzed by GC-MS to obtain the mass chromatogram (see figure). Figure 9 As shown in the figure. The spectral results indicate that there are no hydrocarbon residues on the surface of the mineral particles, meeting the requirements for fragmentation. The GC-MS instrument used in this embodiment is a triple quadrupole gas chromatography-mass spectrometry system. Compared with a single quadrupole mass spectrometer, it has higher compound discrimination ability and detection sensitivity for low-concentration samples, and is more suitable for the detection of crude oil components in inclusions.

[0072] (4) Place the washed oil sample into the zirconia crushing jar, add three different diameter zirconia crushing balls, so that the total volume of the sample and crushing balls occupies one-third of the crushing jar's volume, and then add 40 mL of dichloromethane (analytical grade, redistilled). Place the rubber ring at the jar opening and seal the crushing jar, then use a double nut clamp to tighten the crushing jar to prevent it from detaching during high-speed rotation. After setting the instrument parameters, start the crushing program.

[0073] In this embodiment, Application Example 1 and Application Example 2 are crushed simultaneously. Since the ball mill can process up to four samples simultaneously and needs to maintain diagonal balance to ensure stable operation, the crushing parameters are set as follows: each crushing session lasts 5 minutes, for a total of 3 crushing sessions, with a 10-minute interval between adjacent sessions, to minimize the evaporation loss of oil in the fluid inclusions.

[0074] (5) After crushing, carefully transfer the suspension containing mineral fragments and the crushed pellets from the crushing vessel to a 250 mL beaker. Add 40 mL of dichloromethane to the crushing vessel and soak for 2 hours. Transfer the resulting soaking solution to the same beaker. Repeat this soaking operation twice to ensure that all mineral fragments and extracts in the crushing vessel are fully recovered. Then, place the beaker in an ultrasonic water bath for 15 minutes and let it stand for 5 minutes. Finally, filter the supernatant containing the fluid inclusion extract and suspended fragments through a filter membrane and collect the filtrate in a round-bottom flask.

[0075] (6) The filtrate in the round-bottom flask was concentrated using a rotary evaporator, and then further concentrated to 1 mL by purging with high-purity nitrogen. The resulting concentrate was analyzed by gas chromatography-mass spectrometry (GC-MS), and the results are as follows: Figure 10 As shown, the experimental results indicate that a large amount of crude oil was successfully extracted from the inclusions using this method; no obvious unresolved complex mixture (UCM) peaks were observed in the obtained spectrum, indicating that the crude oil did not undergo significant biodegradation; the main peak carbon number of the crude oil was C21, reflecting its high maturity, but lower than that of the sample in Example 1. This result is consistent with the observed characteristics of the main fluorescence peak wavelength and fluorescence color.

[0076] Application Examples 1 and 2 demonstrate that this invention achieves a systematic improvement in experimental efficiency through three core improvements: precise front-end screening, parallel processing of multiple samples, and standardized workflow. Specifically, rapid screening based on fluorescence characteristics avoids invalid experiments at the source; the multi-tank parallel design of the dedicated ball mill increases the sample processing capacity per unit time by several times; and the standardized workflow customized for different minerals significantly shortens the operation cycle and reduces trial-and-error costs. These improvements work together to achieve a qualitative leap in overall experimental efficiency while ensuring data quality.

[0077] This invention avoids invalid experiments from the source by using rapid screening based on fluorescence characteristics; the multi-tank parallel design of the dedicated ball mill increases the sample processing capacity per unit time by several times; and the standardized process customized for different minerals significantly shortens the operation cycle and reduces trial and error costs, achieving a qualitative leap in overall experimental efficiency while ensuring data quality.

[0078] It should be noted that:

[0079] The oil inclusion components were analyzed using a gas chromatography-mass spectrometry (GC-MS) system, specifically an Agilent GC(8890)-MS(7000E) instrument. The chromatographic conditions were as follows: HP-5ms quartz capillary column (60m × 0.25mm × 0.25μm); temperature program: 50℃ for 1 min, ramp rate from 50℃ to 120℃ at 20℃ / min, ramp rate from 120℃ to 310℃ at 3℃ / min, and ramp at 315℃ for 25 min; injector temperature: 300℃; carrier gas: He; flow rate: 1.00 ml / min; detection method: ion detection; ionization energy: 70 eV; ion source temperature: 230℃.

[0080] The instrument used for scanning microscopy of fluid inclusions in thin sections was an X-max20 energy dispersive spectrometer.

[0081] The instrument used for microscopic observation of calcite and quartz mineral inclusions was a petroleum inclusion microthermometry system, model ECLIPSE Ni-U from Nikon.

[0082] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for single-phase oil inclusion composition analysis based on crude oil inclusions, characterized in that, Includes the following steps: (1) Collect rock samples and prepare fluid inclusion slides; (2) Select rock samples that meet the requirements by fluorescence microscopy and quantitative fluorescence analysis; (3) The grinding mesh number was determined based on the maximum diameter of the oil inclusions obtained by fluorescence microscopy and quantitative fluorescence analysis, and the selected rock samples were ground. (4) The ground rock samples are cleaned to remove hydrocarbon residues on the surface of the particles. The specific cleaning process is as follows, depending on the mineral type: For calcite minerals, ultrasonic cleaning is performed in sequence with methanol, a mixed solution of dichloromethane and methanol, and dichloromethane. Each reagent is used to clean 2 to 3 times, and each cleaning time is 10 to 15 minutes to ensure that the hydrocarbon substances on the surface of the mineral particles are completely removed. For quartz minerals, firstly, ultrasonic cleaning with 10% hydrogen peroxide for 10-15 minutes is performed to remove organic matter between mineral particles; then, ultrasonic cleaning with 5% dilute hydrochloric acid for 10-15 minutes is performed to dissolve and remove carbonate minerals; next, the sample is placed in boiling aqua regia and reacted for 5-10 minutes to thoroughly remove sulfides and iron and manganese oxides; the sample is repeatedly rinsed with distilled water until the aqua regia is completely removed, and then dried; then, ultrasonic cleaning is performed sequentially with methanol, a mixture of dichloromethane and methanol, and dichloromethane, with each reagent used 2-3 times, 10-15 minutes each time, to ensure that residual hydrocarbons on the surface of the mineral particles are completely removed; (5) The rock sample with the hydrocarbon residues on the surface completely removed was subjected to short-term crushing in stages. A crushing device equipped with zirconium oxide crushing balls was used for crushing. Solvent was added to the crushing device for crushing while the mineral particles were soaked to dissolve the mineral particles in the solvent. (6) After dissolving, transfer all the fine mineral fragments in the crushing device to a beaker; treat the solution in the beaker with ultrasound and let it stand; filter the supernatant containing the fluid inclusion extract and suspended mineral fragments through a filter membrane, and pass the filtrate into a round-bottom flask. (7) The filtrate containing the fluid inclusion extract was concentrated; the round-bottom flask containing the filtrate was placed in a rotary evaporator for initial concentration, and then further concentrated by purging with high-purity nitrogen. (8) The concentrated solution was analyzed by gas chromatography-mass spectrometry to determine the composition of the oil inclusions.

2. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, In step (2), when selecting carbonate rock samples, choose rock samples with well-developed cement, abundant veins, and large calcite mineral grains, and confirm that the matrix does not contain secondary fluid inclusions; if the conditions are met, the rock samples are included in the experimental scope; for clastic rock samples, choose rock samples with low mud content and granular support structure. By combining fluorescence microscopy and quantitative fluorescence analysis, the particle size of oil inclusions was accurately determined, and samples containing only single-phase oil inclusions were screened out.

3. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, In step (3), the grinding mesh size is smaller than the maximum diameter of the observed oil inclusions.

4. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, The volume ratio of dichloromethane to methanol in the mixed solution is 93:

7.

5. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, The method to confirm that the residual hydrocarbons on the surface of mineral particles have been completely removed is as follows: take the last cleaning solution as the sample to be tested and perform gas chromatography-mass spectrometry analysis to detect whether it contains residual hydrocarbons; if residual hydrocarbons are detected, the cleaning operation in step (4) needs to be repeated; if not detected, it indicates that the hydrocarbons have been completely removed.

6. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, In step (5), the crushing device includes at least one crushing tank, and each crushing tank contains three different diameter zirconia crushing balls of 4 mm, 8 mm and 10 mm. The total volume of the sample and the crushing balls accounts for one-third of the volume of the crushing tank.

7. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, In step (5), after adding dichloromethane, the instrument parameters are set to 5 minutes for each crushing time, 3 crushing times in total, and 10 minutes between two adjacent crushing times.

8. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, In step (6), the solvent is dichloromethane; after opening the crushing device, pour the suspension containing fine mineral fragments into a beaker, and also gently pour the zirconia crushing balls into the beaker; then add dichloromethane to the crushing tank and soak for 2 hours, then transfer the soaked solution to the beaker, repeat the operation until all the extracts and mineral fragments in the crushing tank are transferred to the beaker; perform ultrasonic treatment on the solution in the beaker for 15 minutes, and let it stand for 5 minutes.

9. The method for single-phase oil inclusion composition analysis based on crude oil inclusions according to claim 1, characterized in that, In step (7), during concentration, the round-bottom flask containing the filtrate is placed in a rotary evaporator for initial concentration, and then high-purity nitrogen is used for purging for further concentration.

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