Method for testing barium isotope of organic matter-rich rock in carbonate rock oil and gas reservoir

Abstract

The invention relates to a carbonate rock oil and gas reservoir organic matter-rich rock barium isotope testing method, and belongs to the technical field of analytical chemistry. The method comprises the following steps: taking solid asphalt which is in contact with dolomite in a carbonate rock oil and gas reservoir as a raw material, then physically separating the dolomite from the solid asphalt, and selecting the solid asphalt which does not contain dolomite debris as a test object; processing a test object into a powder sample; digesting the powder sample to obtain a digested product; performing medium conversion on the digestion product solution to obtain a medium-converted solution; carrying out secondary separation and purification on the solution subjected to medium conversion by adopting a Teflon material chromatographic column to obtain a sample barium isotope solution to be detected; and performing barium isotope testing on the sample barium isotope solution to be tested. According to the chemical sample dissolving method, the sample dissolving temperature in the whole process is lower than 200 DEG C, and compared with a conventional high-pressure ashing method of an organic matter-rich rock sample, barium isotope fractionation of the sample caused by high temperature is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of analytical chemistry, and in particular relates to a barium isotope testing method for organic-rich rocks in carbonate oil and gas reservoirs. Background Art

[0002] Compared to stable isotopes of metals like lithium, magnesium, and iron, research on barium (Ba) isotopes has lagged behind. Since Nier first determined the stable isotopic composition of barium (Ba) in 1938, it has been frequently used in studies of key processes in the early solar system and natural fission reactors. The development of Multiple-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) has led to breakthroughs in the analysis of barium (Ba) isotopes. While research on barium (Ba) isotopes is still very limited, significant progress has been made in the analysis of barium (Ba) isotopes and in the study of natural samples, including minerals, water, and soil.

[0003] Currently, there are few high-precision methods for measuring barium (Ba) isotopes. In the early days, barium isotope composition was primarily determined by thermal ionization mass spectrometry, but due to the limitations of the measurement technology at the time, the accuracy of barium (Ba) isotope measurements was limited. In 1969, Eugster first used the double-dilution method to measure barium (Ba) isotopes, achieving an analytical accuracy of 1‰. Barium (Ba) isotope measurements of six stony meteorites, silicate inclusions in two iron meteorites, and the terrestrial diabase standard W-1 revealed that the average barium (Ba) isotope composition of meteorites is consistent with that of terrestrial samples within 1‰. Barium (Ba) isotope analysis of 200 million-year-old natural fission reactor-derived uranium deposits from the Oklo and Bangombe uranium deposits revealed the presence of a Ba isotope anomaly. The prerequisite for such research is the simultaneous acquisition of high-precision Ba concentrations and 138Ba / 134Ba isotope ratios.

[0004] Generally speaking, 138 Ba / 134The accuracy of the Ba isotope ratio must be better than 0.05‰ (2RSD). In 2010, Allmen first applied MC-ICP-MS to measure barium (Ba) isotopes, and combined with the double diluent method, he improved the analytical accuracy of barium (Ba) isotopes to 0.15‰. In 2014, Miyazaki, through rigorous calculations, achieved the optimal dilution ratio between the double diluent and the sample, while also correcting for the interference of xenon (Xe) mixed in argon on the isotopes of barium (Ba), improving the accuracy of barium isotope measurements to 0.03‰. He also measured the barium (Ba) isotope composition of some igneous rock standards. The establishment of Ba isotopes using the double diluent method has been recognized by analytical chemists and geochemists, and has been used to establish a method for measuring barium (Ba) isotopes in seawater and corals with extremely low barium (Ba) content.

[0005] In summary, existing barium (Ba) isotope analysis methods are primarily applicable to minerals, water, and soil, but a comprehensive, high-precision method has yet to be established for organic-rich rock samples. Therefore, developing high-precision Ba isotope analysis methods for organic-rich rock samples while maintaining the same precision and accuracy as other types of samples is urgently needed. Summary of the Invention

[0006] To address these issues, the present invention provides a barium isotope analysis method for organic-rich rocks in carbonate oil and gas reservoirs. This method chemically digests organic-rich rock samples and accurately measures their barium (Ba) isotope composition using a multi-acceptor plasma mass spectrometer (MCP-MS) based on a "sample-standard" analysis method. This method simplifies the chemical digestion process for organic-rich rocks, improves chemical digestion efficiency, and provides highly accurate barium (Ba) isotope data through mass spectrometry.

[0007] The present invention aims to provide a method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs, the method comprising:

[0008] Solid asphalt in contact with dolomite in carbonate oil and gas reservoirs is used as raw material. The dolomite and solid asphalt are then physically separated, and the solid asphalt that does not contain dolomite rock fragments is selected as the test object.

[0009] processing the test object into a powder sample;

[0010] Pour the powder sample into a Teflon digestion tank, then add the first HNO3 solution and HF solution, press the cover to mix evenly, heat to 120-125℃, react for 3-4h, then heat to 185-190℃, press the cover to react for 72-90h, cool to room temperature to obtain a reaction solution, transfer the reaction solution to a Teflon beaker, heat to 120-125℃, open the cover and evaporate to dryness, after evaporation, slowly add the second HNO3 solution and the first HCl solution drop by drop to the Teflon beaker, press the cover and heat to 120-125℃, react for more than 24h, then open the cover and evaporate again, after evaporation, slowly add H2O2 drop by drop, let it stand until no bubbles are generated in the solution in the beaker, add the third HNO3 solution and the second HCl solution, press the cover and heat to 120-125℃, react until the solution in the beaker becomes clear and transparent, then keep warm and open the cover and evaporate to dryness to obtain the digestion product;

[0011] Slowly add the third HCl solution to the Teflon beaker containing the evaporated digestion product, cover it, and heat it in an ultrasonic water bath until the solution in the beaker becomes clear and transparent. Then, remove the cover and evaporate it to dryness at 120-125°C. After evaporation, continue to slowly add the fourth HCl solution to obtain a medium conversion solution.

[0012] The solution after medium conversion is subjected to secondary separation and purification using a Teflon chromatography column to obtain a sample barium isotope test solution;

[0013] Perform barium isotope test on the sample barium isotope test solution.

[0014] In an embodiment of the present invention, the particle size of the powder sample is less than 200 mesh.

[0015] In an embodiment of the present invention, the dosage ratio of the powder sample, the first HNO3 solution, the HF solution, the second HNO3 solution, the first HCl solution, H2O2, the third HNO3 solution, and the second HCl solution is 15 mg: 0.6 mL: 1.2 mL: 1 mL: 3 mL: 0.5 mL: 1 mL: 3 mL, the concentrations of the first HNO3 solution, the second HNO3 solution, and the third HNO3 solution are all 15.34 N, the concentrations of the HF solution are all 23 N, and the first HCl solution and the second HCl solution are both 11.6 N.

[0016] In an embodiment of the present invention, when the reaction liquid is transferred to the Teflon beaker, the Teflon digestion tank is moistened with a fourth HNO3 solution, and the wetting liquid obtained after moistening is mixed with the reaction liquid and then transferred to the Teflon beaker together.

[0017] In the embodiment of the present invention, the concentration of the fourth HNO 3 solution is 1N.

[0018] In the embodiment of the present invention, the usage ratio of the third HCl solution, the fourth HCl solution, and the powder sample is 1 mL:1 mL:15 mg, and the concentrations of the third HCl solution and the fourth HCl solution are both 6N.

[0019] In an embodiment of the present invention, the temperature of the ultrasonic water bath heating is 75-80° C. and the heating time is 30-40 minutes.

[0020] In the embodiment of the present invention, the specific operation of the secondary separation and purification is as follows:

[0021] The resin was loaded into a Teflon chromatography column, and 6 mol / L HNO3 solution, 6 mol / L HCl solution, secondary purified water, and 3 mol / L HCl solution were successively added to the Teflon chromatography column. The solution after the medium conversion was dripped into the Teflon chromatography column;

[0022] Add 3 mol / L HCl to the Teflon chromatography column in batches, 1 mL each time.

[0023] Then, 4 mol / L HNO3 was added to the Teflon chromatography column in succession to obtain a separated and purified sample solution;

[0024] The sample solution after the primary separation and purification is evaporated to dryness at 120-125°C to obtain a primary separation and purification sample, and then the primary separation and purification sample is mixed with 6 mol / L HCl to obtain a secondary separation solution;

[0025] The resin was loaded into a Teflon chromatography column, and 6 mol / L HNO3 solution, 6 mol / L HCl solution, secondary purified water and 3 mol / L solution were added to the Teflon chromatography column in sequence. The secondary separation solution was dripped into the Teflon chromatography column;

[0026] Add 3 mol / L HCl to the Teflon chromatography column in batches, 1 mL each time.

[0027] Then, 4 mol / L HNO3 was added to the Teflon chromatography column in succession to obtain the sample solution after secondary separation and purification;

[0028] The sample solution after secondary separation and purification is evaporated to dryness at 120-125° C. to obtain a secondary separation and purification sample, and then the secondary separation and purification sample is mixed with a 2% by mass HNO3 solution to obtain a sample barium isotope test solution.

[0029] In an embodiment of the present invention, the resin is AG50W-X12 resin; during the primary separation and purification, the volume ratio of 6mol / LHNO3 solution, 6mol / L HCl solution, secondary purified water, 3mol / L HCl solution, the solution after medium conversion, 3mol / L HCl solution, and 4mol / L HNO3 solution is 8mL:6mL:5mL:5mL:1mL:28mL:12mL; the volume ratio of the 6mol / L HCl solution to the solution after the medium conversion is 1mL:1mL; during the secondary separation and purification, the volume ratio of 6mol / L HNO3 solution, 6mol / L HCl solution, secondary purified water, 3mol / L HCl solution, secondary separation liquid, 3mol / L HCl solution, and 4mol / LHNO3 solution is 4mL:4mL:3mL:3mL:1mL:9mL:10mL.

[0030] In the embodiment of the present invention, the barium isotope test adopts the sample-standard interpolation method, and the specific operation is as follows:

[0031] Take 1 mL of the test solution and inject it through dry plasma using a membrane desolvation system. At the same time, add 2-3 mL / min of nitrogen and use the Sample cone and X-cut cone to perform Ba isotope analysis. The test solution is a sample barium isotope test solution or an SRM3104a barium standard solution.

[0032] Before and after the measurement of each sample barium isotope test solution, SRM3104a barium standard solution was tested.

[0033] In the embodiment of the present invention, between two sample tests, the sample injection system is cleaned using 5% by mass and 2% by mass HNO3 solutions respectively until the signal of 138Ba is less than 10 mv.

[0034] Beneficial effects of the present invention:

[0035] The present invention selects solid asphalt samples from carbonate oil and gas reservoirs and performs crushing and grinding, chemical dissolution, and secondary separation and purification on ion exchange columns to obtain pure Ba components. Then, mass spectrometry is performed using the sample-standard interpolation method to obtain high-precision Ba isotope composition data of the solid asphalt samples from carbonate oil and gas reservoirs. The method has the following advantages:

[0036] The chemical dissolution method for organic-rich rock samples from carbonate oil and gas reservoirs established in the present invention has a full-process dissolution temperature of less than 200°C. Compared with the conventional high-pressure ashing method for organic-rich rock samples, it avoids the barium isotope fractionation of the sample caused by high temperature (above 600°C).

[0037] The present invention adopts the sample-standard interpolation method to effectively correct the isotope fractionation effect produced during the measurement process and avoid the memory effect produced by the instrument to the greatest extent, greatly improving the accuracy and precision of the test results;

[0038] The present invention provides a new metal stable isotope analysis tool for the scientific research field of carbonate oil and gas reservoirs;

[0039] The method of the present invention is simple, efficient, and widely applicable, and can be further applied to barium isotope analysis of other types of samples;

[0040] This method fills the gap in barium isotope analysis technology in the field of organic-rich rock samples in carbonate oil and gas reservoirs.

[0041] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A flowchart of a method for testing barium isotopes in organic-rich rocks in carbonate oil and gas reservoirs according to an embodiment of the present invention is shown;

[0044] Figure 2 A schematic diagram of the tectonic location and sampling area of ​​the study area according to an embodiment of the present invention is shown;

[0045] Figure 3 A plot of the Ba isotope composition of a sample according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0047] like Figure 1As shown, a method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs according to an embodiment of the present invention includes:

[0048] Step 1: Select the test object: Use solid asphalt in contact with dolomite in carbonate oil and gas reservoirs as raw material, then physically separate the dolomite from the solid asphalt, and select the solid asphalt that does not contain dolomite rock fragments as the test object;

[0049] Step 2: Sample preparation: Process the test object into a powder sample;

[0050] Step 3: Sample dissolution: Pour the powder sample into a Teflon digestion tank, then add the first HNO3 solution and HF solution, press the cover to mix evenly, heat to 120-125℃, react for 3-4h, then heat to 185-190℃, press the cover to react for 72-90h, cool to room temperature to obtain the reaction solution, transfer the reaction solution to a Teflon beaker, heat to 120-125℃, open the cover and evaporate to dryness, after evaporation, slowly add the first HNO3 solution and HF solution drop by drop to the Teflon beaker. The second HNO3 solution and the first HCl solution are heated to 120-125°C with a press cap, and reacted for more than 24 hours. The lid is then opened and evaporated again. After evaporation, H2O2 is slowly added dropwise and allowed to stand until no bubbles are generated in the solution in the beaker. The third HNO3 solution and the second HCl solution are added, the lid is pressed and heated to 120-125°C, and reacted until the solution in the beaker becomes clear and transparent (i.e., no suspended particles or flocculent floating matter is visible to the naked eye). The solution is then opened and evaporated to dryness while maintaining the temperature to obtain the digestion product.

[0051] Step 4, medium conversion: slowly add the third HCl solution to the Teflon beaker containing the evaporated digestion product, press the lid and heat in an ultrasonic water bath, and let it stand until the solution in the beaker becomes clear and transparent (i.e., no suspended particles or flocculent floating matter can be seen with the naked eye), then remove the lid and evaporate to dryness at 120-125°C. After evaporation, continue to slowly add the fourth HCl solution to obtain the medium conversion solution;

[0052] Step 5, secondary separation and purification: The solution after the medium conversion is subjected to secondary separation and purification using a Teflon chromatography column to obtain a sample solution to be tested for barium isotope;

[0053] Step 6: Isotope determination: Use the receiving plasma mass spectrometer to perform barium isotope test on the sample barium isotope test solution.

[0054] The process operations of step 1 and step 2 are completed in a conventional operating room, and steps 4 to 6 are carried out in an ultra-clean laboratory. The chemical reagents used in the process operations are subjected to two sub-boiling distillations.

[0055] In step 2, the test object is processed into a powder sample by crushing and grinding. The crushing device used is a planetary disperser mixer and a 200-mesh screen. The particle size of the powder sample is less than 200 mesh.

[0056] In step 3, the powder sample is weighed using weighing paper on a 1 / 100,000 electronic balance.

[0057] In step three, the dosage ratio of the powder sample, the first HNO3 solution, the HF solution, the second HNO3 solution, the first HCl solution, H2O2, the third HNO3 solution, and the second HCl solution is 15 mg: 0.6 mL: 1.2 mL: 1 mL: 3 mL: 0.5 mL: 1 mL: 3 mL, the concentrations of the first HNO3 solution, the second HNO3 solution, and the third HNO3 solution are all 15.34 N, the concentrations of the HF solution are all 23 N, and the first HCl solution and the second HCl solution are both 11.6 N.

[0058] In step 3, when the reaction liquid is transferred to the Teflon beaker, the Teflon digestion tank is moistened with a fourth HNO3 solution, and the wetting liquid obtained after moistening is mixed with the reaction liquid and then transferred to the Teflon beaker together.

[0059] In step 3, the concentration of the fourth HNO 3 solution is 1N.

[0060] In step 4, the ratio of the added amount of the third HCl solution, the fourth HCl solution and the powder sample is 1 mL:1 mL:15 mg, and the concentrations of the third HCl solution and the fourth HCl solution are both 6N.

[0061] In step 4, the temperature of the ultrasonic water bath heating is 75-80° C. and the heating time is 30-40 min.

[0062] In step 5, the specific operation of the secondary separation and purification is as follows:

[0063] The resin was loaded into a Teflon chromatography column, and 6 mol / L HNO3 solution, 6 mol / L HCl solution, secondary purified water, and 3 mol / L HCl solution were successively added to the Teflon chromatography column. The solution after the medium conversion was dripped into the Teflon chromatography column;

[0064] Add 3 mol / L HCl to the Teflon chromatography column in batches, 1 mL each time.

[0065] Then, 4 mol / L HNO3 was added to the Teflon chromatography column in succession to obtain a separated and purified sample solution;

[0066] The sample solution after the primary separation and purification is evaporated to dryness at 120-125°C to obtain a primary separation and purification sample, and then the primary separation and purification sample is mixed with 6 mol / L HCl to obtain a secondary separation solution;

[0067] The resin was loaded into a Teflon chromatography column, and 6 mol / L HNO3 solution, 6 mol / L HCl solution, secondary purified water, and 3 mol / L HCl solution were successively added to the Teflon chromatography column. The secondary separation solution was dripped into the Teflon chromatography column;

[0068] Add 3 mol / L HCl to the Teflon chromatography column in batches, 1 mL each time.

[0069] Then, 4 mol / L HNO3 was added to the Teflon chromatography column in succession to obtain the sample solution after secondary separation and purification;

[0070] The sample solution after secondary separation and purification is evaporated to dryness at 120-125° C. to obtain a secondary separation and purification sample, and then the secondary separation and purification sample is mixed with a 2% by mass HNO3 solution to obtain a sample barium isotope test solution.

[0071] Wherein, the resin is AG50W-X12 resin; during the primary separation and purification, the volume ratio of 6mol / LHNO3 solution, 6mol / LHCl solution, secondary purified water, 3mol / L HCl solution, the solution after medium conversion, 3mol / L HCl solution, and 4mol / L HNO3 solution is 8mL:6mL:5mL:5mL:1mL:28mL:12mL; the volume ratio of the 6mol / L HCl solution to the solution after the medium conversion is 1mL:1mL; during the secondary separation and purification, the volume ratio of 6mol / L HNO3 solution, 6mol / L HCl solution, secondary purified water, 3mol / L HCl solution, secondary separation liquid, 3mol / L HCl solution, and 4mol / L HNO3 solution is 4mL:4mL:3mL:3mL:1mL:9mL:10mL.

[0072] In step 6, the barium isotope test is performed using the sample-standard interpolation method, and the specific operation is as follows:

[0073] Take 1 mL of the test solution and inject it through dry plasma using a membrane desolvation system. At the same time, add 2-3 mL / min of nitrogen and use the Sample cone and X-cut cone to perform Ba isotope analysis. The test solution is a sample barium isotope test solution or an SRM3104a barium standard solution.

[0074] Before and after the measurement of each sample barium isotope solution, SRM3104a barium standard solution was inserted for testing;

[0075] In the interval between two samples, the injection system was cleaned with 5% and 2% HNO3 solutions respectively until the signal of 138Ba was less than 10mv.

[0076] Example 1:

[0077] Barium isotope testing method for organic-rich rocks in carbonate oil and gas reservoirs:

[0078] Step 1: Kangjiadong in the northern margin of the Sichuan Basin was selected as the study area. Sixteen solid asphalt samples were collected from the carbonate oil and gas reservoirs in the fourth member of the Dengying Formation of the Sinian System in the study area. After screening, nine solid asphalt samples were selected as the subjects for high-precision barium isotope testing of organic-rich rock samples in carbonate oil and gas reservoirs.

[0079] Figure 2 This is a simplified diagram of the tectonic location and sampling area of ​​the study area of ​​this embodiment. Figure 2 Markings in the middle: 1 fault, 2 first-level boundary, 3 second-level boundary, 4 stratigraphic boundary, 5 thrust fault: Anz pre-Sinian basement, A-T2 Sinian-Middle Triassic, T3 Upper Triassic, J Jurassic, K Cretaceous, I Micangshan composite thrust basement uplift belt, II Micangshan southern margin detachment fold belt, III Sichuan North Sag basin composite superimposed fold belt, IV Longmenshan-Micangshan superimposed deformation belt, V Longmenshan-Micangshan superimposed fold belt, VI Longmenshan intracontinental composite orogenic belt, VII Bikou block, VIII Hannan basement thrust uplift belt, I1 Guanba-Shuimo nappe, I2 Dahe-Shangliang nappe, I3 Xidi-Beiba nappe, II1 overthrust fold belt, II1 dual tectonic belt;

[0080] The Sichuan Basin lies on the northwestern margin of the Yangtze Plate. The Sinian System represents the first sedimentary series in the Sichuan Basin, including the Doushantuo Formation, composed of black argillaceous rocks and dolostones, and the Dengying Formation, dominated by grayish-white crystalline (algae-like) dolostones interbedded with argillaceous rocks. Influenced by the Neoproterozoic Tongwan Movement, the dolostones of the Sinian Dengying Formation underwent freshwater karstification. Extensive dissolution cavities developed near the unconformity at the top of the Dengying Formation (Member 4), representing the Formation's highest-quality reservoir. Reservoir solid asphalt is the final product of oil and gas accumulation. Studies of its distribution, elemental abundance, and maturity can quantify the extent of (paleo) oil and gas formation and the scale of its reserves. The burial thermal history of hydrocarbon generation and the morphological characteristics of the reservoir asphalt in the Sinian Dengying Formation on the northern margin of the Sichuan Basin provide a glimpse into the preservation or destruction of reservoir pores. However, the natural gas accumulation process of the Sinian Dengying Formation in the Sichuan Basin generally features multi-stage migration and accumulation, dynamic adjustment, and complex accumulation processes. Therefore, this area is the focus of exploration for carbonate reservoirs in the Sichuan Basin.

[0081] Step 2: Crush and grind the 9 pieces of solid asphalt hand specimens used as test objects in step 1 until the particle size of the sample powder is less than 200 meshes to obtain a solid asphalt powder sample;

[0082] Step 3: Use weighing paper to accurately weigh 15 mg of the powder sample obtained in step 2 on a 1 / 100,000 electronic balance, record the weight, and pour the weighed powder into the bottom of a Teflon digestion tank;

[0083] Step 4: Slowly add 0.6 mL of the first 15.34 N HNO3 solution and 1.2 mL of the 23 N HF solution along the wall of the Teflon digestion tank in step 3, cover it, shake it evenly up and down, and place it on the hot plate of a chemical fume hood at 120 ° C. Press the cover to react for 3-4 hours;

[0084] Then, the Teflon digestion tank was placed in a steel jacket and heated in an electric oven at 185°C for 72 hours. After cooling to room temperature, the reaction solution was obtained.

[0085] Remove the Teflon digestion tank from the steel sleeve, shake it thoroughly to ensure that there is no sample solution hanging on the inner wall and the tank cover, and then use a pipette to transfer the reaction solution in the Teflon digestion tank to a 15 ml Teflon beaker;

[0086] Then use a pipette to add 2 mL of 1N fourth HNO3 solution to the Teflon digestion tank to fully infiltrate it. Then use a pipette to add the infiltrating liquid in the Teflon digestion tank to the 15 mL Teflon beaker and mix it with the reaction solution.

[0087] Then place the 15 ml Teflon beaker on the electric hot plate and evaporate to dryness with the lid open at 120°C; after evaporation, use a pipette to slowly add 1 mL of the second 15.34N HNO3 solution and 3 mL of the first 11.6N HCl solution dropwise to the 15 ml Teflon beaker, tighten the cup lid and place it on the electric hot plate to heat and react at 120°C for more than 24 hours; after the reaction is completed, unscrew the cup lid and continue to evaporate to dryness on the electric hot plate at 120°C; after evaporation, use a pipette to slowly drop 0.5 mL of H2O2 into the 15 ml Teflon beaker, and after the sample solution in the 15 ml Teflon beaker is fully reacted and no bubbles are generated, use a pipette to add 1 ml of the third 15.34N HNO3 solution and 3 ml of the first HCl solution to the 15 ml Teflon beaker. 11.6N second HCl solution, tighten the cup cover and place it on a hot plate to react at 120℃ for more than 24 hours (when the reaction is completed, check whether the solution in the 15 ml Teflon beaker is clear and transparent, and there are no visible suspended particles or flocculent floating objects, which indicates that the sample is completely dissolved and the heating reaction is stopped); then open the 15 ml Teflon beaker and place it on a hot plate to evaporate to dryness at 120℃. After evaporation, the digestion product is obtained;

[0088] Step 5: Use a pipette to add 1 ml of the third 6N HCl solution to the 15 ml Teflon beaker in step 4 to completely dissolve the digestion product, then tighten the cup lid and place it in an ultrasonic water bath for heating for 30 minutes. After the solution in the 15 ml Teflon beaker becomes clear and transparent, with no visible suspended particles or flocculent floating matter, open the 15 ml Teflon beaker and place it on a hot plate to evaporate to dryness at 120° C. After evaporation, use a pipette to add 1 ml of the 6N HCl solution to the 15 ml Teflon beaker to dissolve the evaporated sample to obtain a medium conversion solution.

[0089] Step 6, secondary separation and purification:

[0090] Load 2 mL of AG50W-X12 resin into a 30 mL Teflon chromatography column. Use a pipette to add 8 mL of 6 mol / L HNO3 solution, 6 mL of 6 mol / L HCl solution, 5 mL of secondary purified water, and 5 mL of 3 mol / L HCl solution to the 30 mL Teflon chromatography column in sequence.

[0091] Use a pipette to transfer 1 mL of the medium conversion solution from the 15 mL Teflon beaker in step 5 into a 30 mL Teflon chromatography column. Then, use a pipette to add 28 mL of 3 mol / L HCl solution to the 30 mL Teflon chromatography column (1 mL each time).

[0092] Then, use a pipette to add 12 mL of 4 mol / L HNO3 solution to the 30 mL Teflon chromatography column, and use a 15 mL Teflon beaker to collect the sample solution after the first separation and purification to obtain the sample solution after the first separation and purification;

[0093] Place a 15 mL Teflon beaker with the lid open on a hot plate and evaporate the sample at 120°C. Then, use a pipette to add 1 mL of 6 mol / L HCl to the 15 mL Teflon beaker to fully dissolve the sample to obtain a secondary separation solution.

[0094] Load 0.5 mL of AG50W-X12 resin into a 30 mL Teflon chromatography column. Use a pipette to add 4 mL of 6 mol / L HNO3 solution, 4 mL of 6 mol / L HCl solution, 3 mL of secondary purified water, and 3 mL of 3 mol / L HCl solution to the 30 mL Teflon chromatography column in sequence. Use a pipette to transfer 1 mL of the secondary separation solution in the 15 mL Teflon beaker dropwise into the 30 mL Teflon chromatography column.

[0095] Then, use a pipette to add 9 mL of 3 mol / L HCl to the 30 mL Teflon chromatography column (1 mL each time);

[0096] Then, use a pipette to add 10 mL of 4 mol / L HNO3 solution to the 30 mL Teflon chromatography column in batches and use a 15 mL Teflon beaker to collect the secondary separated liquid. Place the 15 mL Teflon beaker with the lid open on a hot plate and evaporate the sample at 120°C. Then, use a pipette to add 2% HNO3 solution by mass to the 15 mL Teflon beaker, and calibrate the volume of the resulting dissolved liquid to 11 mL, thereby obtaining 1 mL of the sample barium (Ba) isotope test solution.

[0097] Step 7: Determine the isotopic composition. The isotope measurement instrument is a Multiple-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Before each test, instrument parameters must be debugged and optimized. These include the argon and nitrogen flow rates, torque tube, cone, and ion lens on the Aridus II membrane desolvation system panel to ensure instrument stability and a sufficiently strong signal. 1 ml of the barium isotope solution obtained in Step 6 was dry plasma injected using the Aridus II membrane desolvation system, while adding 2-3 ml / min of N2. Ba isotope analysis was performed using the Sample cone and X-cut cone. Under steady-state conditions, the barium concentration on the instrument was 200 ppb, and the sensitivity for 138Ba reached 75 V / ppm. Sixty data points were collected for each sample measurement, each with an integration time of 2.097 s. Between samples, the injection system was cleaned for 3 minutes with 5% (m / m) and 2% (m / m) HNO3, respectively, until the 138Ba signal was less than 10 mV to prevent cross-contamination between measurements. Each sample was measured for approximately 8 minutes. SRM3104a barium standard solution was interpolated before and after each sample measurement. The same sample was measured at least three times in a row. The final result and error for each sample were calculated as the average and twice the standard deviation (2SD) of the multiple replicates. The instrument's mass fractionation effects were corrected using the sample-standard interpolation method.

[0098] Figure 3 This is a plot of the Ba isotope composition of the sample in this embodiment. The plot is consistent with the theoretical kinetic fractionation and equilibrium fractionation indices, indicating that the data obtained by the barium isotope testing method for organic-rich rocks in carbonate oil and gas reservoirs adopted in this embodiment is highly precise and accurate.

[0099] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs, characterized in that: include: Solid asphalt in contact with dolomite in carbonate oil and gas reservoirs is used as raw material. The dolomite and solid asphalt are then physically separated, and the solid asphalt that does not contain dolomite rock fragments is selected as the test object. processing the test object into a powder sample; Pour the powder sample into a Teflon digestion tank, then add the first HNO3 solution and HF solution, press the cover to mix evenly, heat to 120-125℃, react for 3-4h, then heat to 185-190℃, press the cover to react for 72-90h, cool to room temperature to obtain a reaction solution, transfer the reaction solution to a Teflon beaker, heat to 120-125℃, open the cover and evaporate to dryness, after evaporation, slowly add the second HNO3 solution and the first HCl solution drop by drop to the Teflon beaker, press the cover and heat to 120-125℃, react for more than 24h, then open the cover and evaporate again, after evaporation, slowly add H2O2 drop by drop, let it stand until no bubbles are generated in the solution in the beaker, add the third HNO3 solution and the second HCl solution, press the cover and heat to 120-125℃, react until the solution in the beaker becomes clear and transparent, then keep warm and open the cover and evaporate to dryness to obtain the digestion product; Slowly add the third HCl solution to the Teflon beaker containing the evaporated digestion product, cover it, and heat it in an ultrasonic water bath until the solution in the beaker becomes clear and transparent. Then, remove the cover and evaporate it to dryness at 120-125°C. After evaporation, continue to slowly add the fourth HCl solution to obtain a medium conversion solution. The solution after medium conversion is subjected to secondary separation and purification using a Teflon chromatography column to obtain a sample barium isotope test solution; Perform barium isotope test on the sample barium isotope test solution.

2. The method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs according to claim 1, characterized in that: The particle size of the powder sample is less than 200 mesh.

3. The method for barium isotope testing of organic-rich rocks in carbonate oil and gas reservoirs according to claim 1, characterized in that: The dosage ratio of the powder sample, the first HNO3 solution, the HF solution, the second HNO3 solution, the first HCl solution, H2O2, the third HNO3 solution, and the second HCl solution is 15 mg: 0.6 mL: 1.2 mL: 1 mL: 3 mL: 0.5 mL: 1 mL: 3 mL, the concentrations of the first HNO3 solution, the second HNO3 solution, and the third HNO3 solution are all 15.34 N, the concentrations of the HF solution are all 23 N, and the first HCl solution and the second HCl solution are both 11.6 N.

4. The method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs according to claim 1, characterized in that: When the reaction liquid is transferred to the Teflon beaker, the Teflon digestion tank is moistened with the fourth HNO3 solution, and the infiltration liquid obtained after moistening is mixed with the reaction liquid and then transferred to the Teflon beaker together.

5. The method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs according to claim 4, characterized in that: The concentration of the fourth HNO 3 solution is 1N.

6. The method for barium isotope testing of organic-rich rocks in carbonate oil and gas reservoirs according to claim 1, characterized in that: The usage ratio of the third HCl solution, the fourth HCl solution, and the powder sample is 1 mL:1 mL:15 mg, and the concentrations of the third HCl solution and the fourth HCl solution are both 6N.

7. The method for barium isotope testing of organic-rich rocks in carbonate oil and gas reservoirs according to claim 1, characterized in that: The ultrasonic water bath heating temperature is 75-80° C. and the heating time is 30-40 minutes.

8. The method for barium isotope testing of organic-rich rocks in carbonate oil and gas reservoirs according to claim 1, characterized in that: The specific operation of the secondary separation and purification is as follows: The resin was loaded into a Teflon chromatography column, and 6 mol / L HNO3 solution, 6 mol / L HCl solution, secondary purified water, and 3 mol / L HCl solution were successively added to the Teflon chromatography column. The solution after the medium conversion was dripped into the Teflon chromatography column; Add 3 mol / L HCl to the Teflon chromatography column in batches, 1 mL each time. Then, 4 mol / L HNO3 was added to the Teflon chromatography column in succession to obtain a separated and purified sample solution; The sample solution after the primary separation and purification is evaporated to dryness at 120-125°C to obtain a primary separation and purification sample, and then the primary separation and purification sample is mixed with 6 mol / L HCl to obtain a secondary separation solution; The resin was loaded into a Teflon chromatography column, and 6 mol / L HNO3 solution, 6 mol / L HCl solution, secondary purified water and 3 mol / L solution were added to the Teflon chromatography column in sequence. The secondary separation solution was dripped into the Teflon chromatography column; Add 3 mol / L HCl to the Teflon chromatography column in batches, 1 mL each time. Then, 4 mol / L HNO3 was added to the Teflon chromatography column in succession to obtain the sample solution after secondary separation and purification; The sample solution after secondary separation and purification is evaporated to dryness at 120-125° C. to obtain a secondary separation and purification sample, and then the secondary separation and purification sample is mixed with a 2% by mass HNO3 solution to obtain a sample barium isotope test solution.

9. The method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs according to claim 8, characterized in that: The resin is AG50W-X12 resin; during the primary separation and purification, the volume ratio of 6mol / L HNO3 solution, 6mol / L HCl solution, secondary purified water, 3mol / L HCl solution, the solution after medium conversion, 3mol / L HCl solution, and 4mol / L HNO3 solution is 8mL:6mL:5mL:5mL:1mL:28mL:12mL; the volume ratio of the 6mol / L HCl solution to the solution after the medium conversion is 1mL:1mL; during the secondary separation and purification, the volume ratio of 6mol / L HNO3 solution, 6mol / L HCl solution, secondary purified water, 3mol / L HCl solution, secondary separation liquid, 3mol / L HCl solution, and 4mol / L HNO3 solution is 4mL:4mL:3mL:3mL:1mL:9mL:10mL.

10. The barium isotope testing method for organic-rich rocks in carbonate oil and gas reservoirs according to any one of claims 1 to 8, characterized in that: The barium isotope test method used is the sample-standard interpolation method, and the specific operation is as follows: Take 1 mL of the test solution and inject it through dry plasma using a membrane desolvation system. At the same time, add 2-3 mL / min of nitrogen and use the Sample cone and X-cut cone to perform Ba isotope analysis. The test solution is a sample barium isotope test solution or an SRM3104a barium standard solution. Before and after the measurement of each sample barium isotope test solution, SRM3104a barium standard solution was tested.

11. The method for testing barium isotopes of organic-rich rocks in carbonate oil and gas reservoirs according to claim 10, characterized in that: In the interval between two samples, the injection system was cleaned with 5% and 2% HNO3 solutions respectively until the signal of 138Ba was less than 10mv.

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