Device system and method for measuring carbon and oxygen isotopes in micro-area carbonate rocks

Abstract

The invention relates to a device system and a method for measuring carbon and oxygen isotopes in micro-area carbonate rocks. The measuring device system comprises a laser corrosion device, a carbon dioxide enrichment device, a water removal device, an impurity adsorption device, an impurity-gas separation device, an opening shunting device and an isotope measuring device which are connected in sequence, the laser corrosion device comprises a sample pool, and the top of the sample pool is connected with a laser. According to the determination device system provided by the invention, the carbon and oxygen isotope test precision and the test efficiency are remarkably improved, the micro-area area is reduced, the problem that part of carbonate structures cannot be determined is solved, the development of a micro-area carbonate rock structure carbon and oxygen test technology is effectively promoted, and the development of the carbon and oxygen test technology is promoted. The method further promotes the research of carbonate reservoir sedimentary environment, pore water cause, paleoclimate and the like.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum and natural gas geological exploration, and in particular to a device system and method for determining carbon and oxygen isotopes in micro-area carbonate rocks. Background Art

[0002] Carbon and oxygen isotope analysis of carbonate rocks is an important part of carbonate geochemical research and is widely used in carbonate oil and gas geological research. However, the conventional phosphoric acid dissolution method for carbonate carbon and oxygen isotope analysis measures the carbon and oxygen isotopes of mixed components, and cannot separately analyze the structural components of carbonate rocks such as particles, mud, cement, grains and biological frameworks, which limits its application in carbonate geology. Therefore, improving the spatial resolution of carbonate carbon and oxygen isotope analysis, that is, conducting micro-area sampling research, has gradually become the key.

[0003] In the 1990s, a domestic project team led by Professor Qiang Zitong successfully developed a laser micro-area offline sampling device that can be used to analyze the micro-area structure of carbonates. The principle is: in a vacuum of 10 -5 Under the condition of Pa, guided by a helium-neon laser (red light), the target to be analyzed in the sample box is found under a microscope and imaging system, and the laser is started. Under the action of heat, the carbonate decomposes to produce carbon dioxide gas, which is purified in a vacuum purification system using the cold trap principle, and then collected and sent to a mass spectrometer for carbon and oxygen isotope determination. However, the vacuum purification equipment uses a long vacuum pumping time, cumbersome sampling procedures, and low sampling efficiency; at the same time, the sample needs to be transferred to the collection bottle, and the trace gas is further diluted, so the micro-area area is required to be at least 300μm×300μm to meet the instrument test intensity requirements. Therefore, many structural components cannot be analyzed due to their small area.

[0004] CN 110794067A discloses a sample preparation device and method for micro-area analysis of carbonate carbon-oxygen isotopes, which comprises a phosphoric acid capillary micro-injector and a carbonate sample pool; a helium inlet and a carbon dioxide outlet are respectively arranged on the side of the carbonate sample pool cavity, and a microinjection needle opening is arranged on the top cover; the outlet of the phosphoric acid capillary micro-injector injects phosphoric acid into the sample in the carbonate sample pool through a microinjection needle, and the carbon dioxide outlet is connected to a carbon-oxygen isotope tester; a sample rack is mounted on an electrically controlled three-axis sample stage, and a temperature control plate is arranged at the bottom of the sample rack. The invention adopts a microinjection needle to inject phosphoric acid micro-droplets to react with carbonate samples, but there is a problem of relatively complex reaction control.

[0005] CN 116413104A discloses an ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon and oxygen isotope micro-area in-situ analysis system and method, which utilizes an ultraviolet laser with a wavelength of 193nm to ablate carbonate aerosol particles from a sample to be tested in a closed environment; utilizes a helium flow to carry the ablated carbonate aerosol particles into a CO2 gas preparation device in a closed environment for reaction to obtain a mixed gas containing CO2 gas; enriches and purifies the mixed gas containing CO2 gas to obtain target CO2 gas; utilizes a back-blowing helium flow to supply the target CO2 gas to a gas isotope ratio mass spectrometer through a micro-dividing interface to obtain the test result. In the invention, the carbon dioxide gas is not further purified, which will lead to a decrease in the test accuracy.

[0006] In view of the shortcomings of the existing technology, there is an urgent need to provide a device system for determining carbon and oxygen isotopes in micro-area carbonate rocks with a small micro-area area, high testing efficiency and accuracy. Summary of the invention

[0007] The purpose of the present invention is to provide a device system and method for determining carbon and oxygen isotopes in micro-area carbonate rocks, which significantly improves the test accuracy and test efficiency of carbon and oxygen isotopes, significantly reduces the micro-area area, and solves the problem that some carbonate structures cannot be determined.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides a device system for determining carbon and oxygen isotopes in micro-area carbonate rocks, the device system comprising a laser ablation device, a carbon dioxide enrichment device, a water removal device, an impurity adsorption device, a foreign gas separation device, an opening diversion device and an isotope determination device connected in sequence;

[0010] The laser ablation device comprises a sample pool, and the top of the sample pool is connected with a laser.

[0011] The measuring device system provided by the present invention adopts a laser ablation device to make the carbonate rock micro-area structure produce carbon dioxide gas, and combines with a water removal device, an impurity adsorption device and a miscellaneous gas separation device to completely remove impurities in the carbon dioxide gas, thereby improving the test accuracy and test efficiency of carbon and oxygen isotopes, solving the problem that some carbonate structures cannot be measured, and effectively promoting the development of micro-area carbonate rock structure carbon and oxygen testing technology, and further promoting the research on carbonate reservoir sedimentary environment, pore water genesis, paleoclimate, etc.

[0012] Preferably, the output mode of the laser includes pulse output or continuous output.

[0013] Preferably, the laser comprises a Nd:YAG laser.

[0014] The working medium of the Nd:YAG laser is yttrium aluminum garnet doped with neodymium ions, and the activating ions are neodymium ions. For refractory carbonate rock sample structures such as cement, pulse output with large instantaneous energy is selected, and for easily decomposed carbonate rock structures, continuous output is selected.

[0015] Preferably, the output current of the Nd:YAG laser is 9-20A, and the output power is 5-50W.

[0016] The output current of the Nd:YAG laser is 9-20A, for example, 9A, 15A or 20A, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] The output power of the Nd:YAG laser is 5-50W, for example, 5W, 25W or 50W, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the output laser wavelength of the Nd:YAG laser is 1.06 μm.

[0019] Preferably, the Nd:YAG laser is assisted by a He—Ne collimated laser.

[0020] The He-Ne collimated laser is a 1Mw low-energy He-Ne collimated laser. The He-Ne collimated laser is used to mark the carbonate rock structure to be analyzed, showing red spots. The optical paths of the He-Ne collimated laser and the Nd:YAG laser are consistent.

[0021] Preferably, the laser ablation device also includes a microscope and an imaging system.

[0022] Preferably, a laser introduction device is provided above the objective lens of the microscope and imaging system, and the laser light path of the laser introduction device is coaxially installed with the light path of the microscope and imaging system via a dichroic mirror.

[0023] Preferably, an air inlet and an air outlet are provided on the side wall of the sample pool, and the central axis where the air inlet is located is lower than the central axis where the air outlet is located.

[0024] Preferably, the air inlet is connected to a stainless steel pipeline with a diameter of 1 / 8" or 1 / 16" and an internal polishing treatment, and the front end of the stainless steel pipeline is connected to a carrier gas flow controller.

[0025] Preferably, the gas outlet is connected to a stainless steel pipeline with a diameter of 1 / 8" or 1 / 16" and a polished interior.

[0026] Preferably, the distance between the central axis of the air inlet and the air outlet is 4-6 cm, for example, 4 cm, 5 cm or 6 cm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 5 cm.

[0027] Preferably, the sample pool is made of stainless steel with a polished inner wall.

[0028] Preferably, the sample pool is a cylinder with a diameter of 8-10 cm and a height of 6-10 cm.

[0029] The diameter of the sample pool is 8-10 cm, for example, 8 cm, 9 cm or 10 cm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 9 cm.

[0030] The height of the sample pool is 6-10 cm, for example, 6 cm, 8 cm or 10 cm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 8 cm.

[0031] Preferably, a quartz glass window is provided on the top of the sample cell.

[0032] Preferably, the thickness of the quartz glass window is 4-6 mm, for example, 4 mm, 5 mm or 6 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 5 mm.

[0033] Preferably, the diameter of the quartz glass window is 8-10 cm, for example, 8 cm, 9 cm or 10 cm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 9 cm.

[0034] Preferably, the quartz glass window is in the shape of a cylinder.

[0035] A silicone O-ring is arranged between the quartz glass window and the sample pool, and a silicone O-ring is also arranged between the quartz glass window and the sample pool cover, so as to achieve the purpose of sealing.

[0036] Preferably, the carbon dioxide enrichment device comprises a cold trap immersed in liquid nitrogen.

[0037] Preferably, the cold trap comprises a U-shaped stainless steel pipeline with a polished interior.

[0038] Preferably, the U-shaped stainless steel pipeline has a diameter of 1 / 16"-1 / 8" and a depth of 8-12 cm.

[0039] The diameter of the U-shaped stainless steel pipeline is 1 / 16"-1 / 8", for example, it can be 1 / 16" or 1 / 8", but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] The depth of the U-shaped stainless steel pipeline is 8-12 cm, for example, 8 cm, 10 cm or 12 cm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 10 cm.

[0041] Preferably, the dewatering device is filled with a dewatering agent.

[0042] Preferably, the dewatering agent comprises any one or a combination of at least two of magnesium perchlorate, silica gel or lime powder. Typical but non-limiting combinations include a combination of magnesium perchlorate and silica gel, a combination of silica gel and lime powder, or a combination of magnesium perchlorate, silica gel and lime powder.

[0043] Preferably, the filling amount of the dehydrating agent is 6-10 g, and the filling length is 5-8 cm.

[0044] The filling amount of the dehydrating agent is 6-10g, for example, 6g, 8g or 10g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 10g.

[0045] The filling length of the dehydrating agent is 5-8 cm, for example, 5 cm, 6 cm or 8 cm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 8 cm.

[0046] Preferably, the impurity adsorbing device is filled with impurity adsorbing material.

[0047] Preferably, the impurity adsorption material comprises PorapakQ adsorbent with a mesh size of 80-100 meshes and a length of 10-15 cm.

[0048] The mesh size of the impurity adsorbing material is 80-100 meshes, for example, 80 meshes, 90 meshes or 100 meshes, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 100 meshes.

[0049] The length of the impurity adsorbing material is 10-15 cm, for example, 10 cm, 12 cm or 15 cm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 15 cm.

[0050] The Porapak Q adsorbent includes porous ethylstyrene, divinylbenzene polymer and silver filaments.

[0051] Preferably, the impurity adsorption device is U-shaped.

[0052] Preferably, the impurity gas separation device comprises a quartz capillary column.

[0053] The quartz capillary column used in the present invention has the characteristics of high melting point, low thermal expansion coefficient, good chemical stability and high tensile strength.

[0054] Preferably, the inner diameter of the quartz capillary column is 0.32 mm and the column length is 30 m.

[0055] Preferably, the column carrier gas flow rate of the quartz capillary column is 100-200 mL / min, for example, 100 mL / min, 180 mL / min or 200 mL / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 180 mL / min.

[0056] Preferably, the column temperature of the quartz capillary column is 50-80°C, for example, 50°C, 60°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 60°C.

[0057] The open flow splitter device can allow the carbon dioxide reference gas and the purified carbon dioxide gas prepared from the sample to alternately enter the gas mass spectrometer for carbon and oxygen isotope analysis.

[0058] Preferably, the isotope determination device comprises a continuous flow gas stable isotope mass spectrometer.

[0059] The continuous flow gas stable isotope mass spectrometer adopts a continuous flow isotope ratio mass spectrometer of model Delta VAdvantage produced by ThermoFisher Company, which is equipped with three air inlet needle valves. The state of the mass spectrometer is detected before starting the sample measurement, requiring that the water peak background in the ion source is less than 2000mV, preferably less than 1000mV; the argon background is less than 40mV, preferably less than 20mV.

[0060] In a second aspect, the present invention provides a method for measuring carbon and oxygen isotopes in micro-area carbonate rocks using the measuring device system described in the first aspect, the method comprising the following steps:

[0061] Carbonate rock samples are treated by laser ablation to obtain a carbon dioxide mixed gas; the carrier gas and the obtained carbon dioxide mixed gas are successively treated by enrichment, water removal, impurity adsorption and impurity gas separation, and the obtained purified carbon dioxide gas is subjected to carbon and oxygen isotope determination.

[0062] The method for determining carbon and oxygen isotopes in micro-area carbonate rocks provided by the present invention overcomes the key defects of the prior art in the carbon and oxygen isotope analysis of carbonate rock micro-area structures, such as high background, incomplete impurity removal and low efficiency, by controlling various process parameters in the laser ablation treatment and separation and purification steps, and significantly improves the test efficiency and test accuracy of carbon and oxygen isotope analysis.

[0063] Preferably, the carbonate rock sample is a thin slice obtained by cutting and single-side polishing.

[0064] Preferably, the thickness of the sheet is 60-80 μm, for example, 60 μm, 70 μm or 80 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0065] Preferably, the carrier gas is purged before the laser ablation process until the carbon dioxide gas test baseline background is less than 5mV, for example, it can be 4mV, 3mV or 2mV, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] Preferably, the carrier gas comprises an inert gas.

[0067] Preferably, the inert gas comprises helium.

[0068] Preferably, the flow rate of the helium is 0.1-200 mL / min, for example, 0.1 mL / min, 180 mL / min or 200 mL / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 180 mL / min.

[0069] Preferably, the carrier gas is used to test the air tightness of the sample cell before the purging process, and the flow rate of helium is 100-150 ml / min. The gas outlet of the sample cell is closed, and the helium flow rate should drop to 0 in 2-3 minutes.

[0070] Preferably, the current of the laser ablation treatment is 10-20A, for example, 10A, 15A or 20A, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0071] Preferably, the laser ablation treatment time is 5-30 s, for example, 5 s, 8 s or 30 s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0072] In the enrichment process, the carbon dioxide mixed gas from the sample pool is frozen in a cold trap, and after all the carbon dioxide mixed gas is transferred to the cold trap, the liquid nitrogen is removed and the carbon dioxide mixed gas is released in a centralized manner.

[0073] The impurity adsorption treatment can remove residual organic matter and sulfur.

[0074] In the carbon and oxygen isotope determination, the purified carbon dioxide gas from the impurity separation device enters the isotope determination device through the open diversion device and the isotope determination device needle valve, and the test method and test procedure are edited to perform carbon and oxygen isotope testing of the carbon dioxide gas.

[0075] Compared with the prior art, the present invention has the following beneficial effects:

[0076] The measuring device system provided by the present invention adopts a laser ablation device to make the carbonate rock micro-area structure produce carbon dioxide gas, and combines a water removal device, an impurity adsorption device and a miscellaneous gas separation device to completely remove impurities in the carbon dioxide gas, and the carbon isotope test accuracy is improved to ±0.12‰, the oxygen isotope test accuracy is improved to ±0.18‰, the single-point test time is shortened to 15min, and the test efficiency is improved by nearly 10 times; the micro-area area is reduced to less than 150μm×150μm, which solves the problem that some carbonate structures cannot be measured, effectively promotes the development of micro-area carbonate rock structure carbon and oxygen testing technology, and further promotes the research on carbonate reservoir sedimentary environment, pore water genesis, paleoclimate and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is a schematic diagram of the structure of the device system for determining carbon and oxygen isotopes in micro-area carbonate rocks provided in Example 1 of the present invention;

[0078] Among them: 1, carbon dioxide enrichment device; 2, water removal device; 3, impurity adsorption device; 4, quartz capillary column; 5, open splitter device; 6, continuous flow gas stable isotope mass spectrometer; 7, sample cell; 8, Nd:YAG laser; 9, gas inlet; 10, gas outlet; 11, carrier gas flow controller. DETAILED DESCRIPTION

[0079] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0080] Example 1

[0081] This embodiment provides a device system for determining carbon and oxygen isotopes in micro-area carbonate rocks, such as Figure 1As shown, the measuring device system includes a laser ablation device, a carbon dioxide enrichment device 1, a water removal device 2, an impurity adsorption device 3, a quartz capillary column 4, an open splitter device 5 and a continuous flow gas stable isotope mass spectrometer 6 which are connected in sequence; the laser ablation device includes a stainless steel sample cell 7 with a polished inner wall, and a Nd:YAG laser 8 is connected to the top of the sample cell 7;

[0082] The output mode of the Nd:YAG laser 8 is continuous output, and the output laser wavelength is 1.06 μm; the Nd:YAG laser 8 is assisted by a 1Mw low-energy He-Ne collimated laser; the laser ablation device also includes a microscope and an imaging system, and a laser introduction device is arranged above the objective lens of the microscope and the imaging system, and the laser light path of the laser introduction device is coaxially installed with the microscope and the imaging system light path through a dichroic mirror;

[0083] The side wall of the sample pool 7 is provided with an air inlet 9 and an air outlet 10, the central axis of the air inlet 9 is lower than the central axis of the air outlet 10; the air inlet 9 is connected to a stainless steel pipeline with a diameter of 1 / 8" and an internal polishing treatment, and the front end of the stainless steel pipeline is connected to a carrier gas flow controller 11; the air outlet 10 is connected to a stainless steel pipeline with a diameter of 1 / 8" and an internal polishing treatment; the distance between the central axis of the air inlet 9 and the air outlet 10 is 5 cm; the sample pool 7 is a cylinder with a diameter of 9 cm and a height of 8 cm; the top of the sample pool 7 is provided with a quartz glass window with a thickness of 5 mm and a diameter of 9 cm;

[0084] The carbon dioxide enrichment device 1 includes a cold trap, which is immersed in liquid nitrogen; the cold trap is a U-shaped stainless steel pipeline with a polished interior, the diameter of the U-shaped stainless steel pipeline is 1 / 8", and the depth is 10cm; the dehydration device 2 is filled with magnesium perchlorate, the filling amount of the magnesium perchlorate is 10g, and the filling length is 8cm; the impurity adsorption device 3 is filled with PorapakQ adsorbent with a mesh size of 100 mesh and a length of 15cm, and the shape of the impurity adsorption device 3 is U-shaped; the inner diameter of the quartz capillary column 4 is 0.32mm, the column length is 30m, the column carrier gas flow rate is 180mL / min, and the column temperature is 60°C; the open splitter device 5 is also connected to a CO2 reference gas.

[0085] Example 2

[0086] This embodiment provides a device system for determining carbon and oxygen isotopes in micro-area carbonate rocks. The difference from Embodiment 1 is that the impurity adsorption material filled in the impurity adsorption device 3 is replaced by lime powder, activated carbon and cotton wool, and the rest is the same as Embodiment 1.

[0087] Example 3

[0088] This embodiment provides a device system for determining carbon and oxygen isotopes in micro-area carbonate rocks. The difference from Embodiment 1 is that the interior of the cold trap is not polished, and the rest is the same as Embodiment 1.

[0089] Comparative Example 1

[0090] This comparative example provides a device system for determining carbon and oxygen isotopes in micro-area carbonate rocks. The difference from Example 1 is that the impurity adsorption device 3 is not provided, and the rest is the same as Example 1.

[0091] Application Example 1

[0092] This application example provides a method for measuring carbon and oxygen isotopes in micro-area carbonate rocks using the measuring device system provided in Example 1, and the method comprises the following steps:

[0093] Helium with a flow rate of 120 ml / min was introduced, and the gas outlet of the sample cell was closed to test the air tightness of the sample cell. Then, the sample cell and pipeline were purged with helium until the baseline background of the carbon dioxide gas test was 4 mV. The carbonate rock sample slice with a thickness of 60 μm obtained by cutting and single-side polishing was laser ablated at a current of 15 A for 8 seconds to obtain a carbon dioxide mixed gas. Helium with a flow rate of 180 ml / min and the obtained carbon dioxide mixed gas were successively subjected to enrichment treatment, water removal treatment, impurity adsorption treatment and impurity gas separation treatment, and the obtained purified carbon dioxide gas was used for carbon and oxygen isotope determination.

[0094] The method provided in this application example includes the following steps:

[0095] (1) Conduct core observation and sample typical phenomena: The carbonate rock samples come from the first section of the Dengying Formation in the Sichuan Basin. The core observation mainly includes the description of rock type, sedimentary structure, diagenetic phenomenon and reservoir characteristics, and preliminarily determines the rock depositional environment and epigenetic transformation. The sampled carbonate rock samples need to cover as many diagenetic phenomena as possible to reveal as much diagenetic information as possible. The sample size is 6 cm × 3 cm × 3 cm;

[0096] (2) Indoor sample preparation, peeling and cleaning: Cut and grind the structure to be analyzed in the carbonate rock sample into thin sections with a thickness of 60 μm and a length and width of 3 cm × 3 cm. Use fir glue to prepare the thin sections. After the thin sections are prepared, peel them off and clean the fir glue stuck on the thin sections. The specific operation includes: baking the thin sections on a resistance furnace for 1 min, taking out the thin sections and soaking them in anhydrous ethanol for 10 min, then repeatedly wiping the fir glue on the thin sections with cotton balls, and drying them at 105°C for analysis. Before testing, find the carbonate structure to be analyzed under a microscope.

[0097] (3) Enrichment of carbon dioxide mixed gas: Place the slice in the sample pool, control the helium flow rate to 120 ml / min, perform airtightness test on the sample pool, and then use helium to purge the sample pool and pipeline until the carbon dioxide gas test baseline background is 4 mV; find the structure to be analyzed under a microscope, use the red light emitted by the He-Ne collimated laser as a guide, start the Nd:YAG laser, and perform laser ablation on the carbonate rock sample slice at a current of 15 A for 8 seconds. The ablation point area is 150 μm × 150 μm, and the generated carbon dioxide mixed gas is enriched in the cold trap;

[0098] (4) Transfer and purification of carbon dioxide gas: Remove the liquid nitrogen outside the cold trap, release the carbon dioxide mixed gas in a centralized manner, and pass through a water removal device, an impurity adsorption device, and a quartz capillary column in sequence to remove water, organic hydrocarbon compounds, and sulfides in the carbon dioxide mixed gas, and then separate it from O2 and CO in sequence. The resulting purified carbon dioxide gas passes through an open splitter device and a needle valve of a continuous flow gas stable isotope mass spectrometer and enters a continuous flow gas stable isotope mass spectrometer for carbon and oxygen isotope determination;

[0099] (5) Carbon and oxygen isotope test of carbon dioxide gas: Check the working status of the continuous flow gas stable isotope mass spectrometer, and use the thin slices made of national standard samples GBW04405 and GBW04406 to calibrate the carbon and oxygen stable isotopes; edit the test method and test program in the control interface of the continuous flow stable isotope mass spectrometer, execute the test program to start the test, and obtain the carbon and oxygen isotope values ​​of the purified carbon dioxide gas.

[0100] The test accuracy of the obtained carbon isotope is 0.12‰, and the test accuracy of the oxygen isotope is 0.18‰, indicating that the test accuracy of carbon and oxygen isotopes is relatively high.

[0101] Application Example 2

[0102] This application example provides a method for determining carbon and oxygen isotopes in micro-area carbonate rocks using the determination device system provided in Example 1. In the steps of the method, the current of the laser ablation treatment is adjusted to 20A and the time is 5 minutes for the refractory carbonate structure to be analyzed, and the rest is the same as in Application Example 1.

[0103] The test accuracy of the obtained carbon isotope is 0.12‰, and the test accuracy of the oxygen isotope is 0.18‰, indicating that the test accuracy of carbon and oxygen isotopes is relatively high.

[0104] Application Example 3

[0105] This application example provides a method for determining carbon and oxygen isotopes in micro-area carbonate rocks using the determination device system provided in Example 2. The steps of the method are the same as those in Application Example 1.

[0106] The test accuracy of the obtained carbon isotope is 0.2‰, and the test accuracy of the oxygen isotope is 0.3‰, which shows that the adsorption of organic matter and sulfur in the carbon dioxide mixture is incomplete, which has a great influence on the test accuracy of carbon and oxygen isotopes.

[0107] Application Example 4

[0108] This application example provides a method for determining carbon and oxygen isotopes in micro-area carbonate rocks using the determination device system provided in Example 3. The steps of the method are the same as those in Application Example 1.

[0109] The test accuracy of the obtained carbon isotope is 0.25‰, and the test accuracy of the oxygen isotope is 0.36‰, which indicates that the water removal effect in the carbon dioxide mixed gas is reduced, which has a great impact on the test accuracy of carbon and oxygen isotopes.

[0110] Comparative application example 1

[0111] This comparative application example provides a method for determining carbon and oxygen isotopes in micro-area carbonate rocks using the determination device system provided in Comparative Example 1. The steps of the method do not involve impurity adsorption treatment, and the rest is the same as Application Example 1.

[0112] The test accuracy of the obtained carbon isotope is 0.26‰, and the test accuracy of the oxygen isotope is 0.38‰, indicating that the organic matter and sulfur have not been removed from the carbon dioxide mixture, which has an adverse effect on the test accuracy of carbon and oxygen isotopes.

[0113] In summary, the measuring device system provided by the present invention adopts a laser ablation device to make the carbonate rock micro-area structure produce carbon dioxide gas, and combines a water removal device, an impurity adsorption device and a miscellaneous gas separation device to completely remove impurities in the carbon dioxide gas, and the carbon isotope test accuracy is improved to ±0.12‰, the oxygen isotope test accuracy is improved to ±0.18‰, the single-point test time is shortened to 15min, and the test efficiency is improved by nearly 10 times; the micro-area area is reduced to less than 150μm×150μm, which solves the problem that some carbonate structures cannot be measured, effectively promotes the development of micro-area carbonate rock structure carbon and oxygen testing technology, and further promotes the research on carbonate reservoir sedimentary environment, pore water genesis, paleoclimate, etc.

[0114] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A device system for determining carbon and oxygen isotopes in micro-area carbonate rocks, characterized in that: The measuring device system comprises a laser ablation device, a carbon dioxide enrichment device, a water removal device, an impurity adsorption device, a foreign gas separation device, an opening diversion device and an isotope measuring device connected in sequence; The laser ablation device comprises a sample pool, and the top of the sample pool is connected with a laser.

2. The measuring device system according to claim 1, characterized in that: The output mode of the laser includes pulse output or continuous output; Preferably, the laser comprises a Nd:YAG laser; Preferably, the output laser wavelength of the Nd:YAG laser is 1.06 μm; Preferably, the Nd:YAG laser is assisted by a He—Ne collimated laser.

3. The measuring device system according to claim 1 or 2, characterized in that: The side wall of the sample pool is provided with an air inlet and an air outlet, and the central axis of the air inlet is lower than the central axis of the air outlet; Preferably, the sample pool is a cylinder with a diameter of 8-10 cm and a height of 6-10 cm; Preferably, a quartz glass window is provided on the top of the sample cell.

4. The measuring device system according to any one of claims 1 to 3, characterized in that: The carbon dioxide enrichment device comprises a cold trap, and the cold trap is immersed in liquid nitrogen; Preferably, the cold trap comprises a U-shaped stainless steel pipeline with a polished interior; Preferably, the U-shaped stainless steel pipeline has a diameter of 1 / 16"-1 / 8" and a depth of 8-12 cm.

5. The measuring device system according to any one of claims 1 to 4, characterized in that: The dewatering device is filled with a dewatering agent; Preferably, the dewatering agent comprises any one or a combination of at least two of magnesium perchlorate, silica gel or lime powder; Preferably, the filling amount of the dehydrating agent is 6-10 g, and the filling length is 5-8 cm; Preferably, the impurity adsorption device is filled with impurity adsorption material; Preferably, the impurity adsorbing material comprises Porapak Q adsorbent with a mesh size of 80-100 meshes and a length of 10-15 cm.

6. The measuring device system according to any one of claims 1 to 5, characterized in that: The impurity gas separation device comprises a quartz capillary column; Preferably, the column carrier gas flow rate of the quartz capillary column is 100-200 mL / min; Preferably, the column temperature of the quartz capillary column is 50-80°C.

7. A method for measuring carbon and oxygen isotopes in micro-area carbonate rocks by using the measuring device system according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: Carbonate rock samples are treated by laser ablation to obtain a carbon dioxide mixed gas; the carrier gas and the obtained carbon dioxide mixed gas are successively treated by enrichment, water removal, impurity adsorption and impurity gas separation, and the obtained purified carbon dioxide gas is subjected to carbon and oxygen isotope determination.

8. The method according to claim 7, characterized in that The carbonate rock sample is a thin slice obtained by cutting and single-side polishing; Preferably, the thickness of the sheet is 60-80 μm.

9. The method according to claim 7 or 8, characterized in that: The carrier gas is purged before the laser ablation process until the baseline background of the carbon dioxide gas test is less than 5mV; Preferably, the carrier gas comprises an inert gas; Preferably, the inert gas comprises helium; Preferably, the flow rate of the helium gas is 0.1-200 mL / min.

10. The method according to any one of claims 7 to 9, characterized in that: The current of the laser ablation treatment is 10-20A; Preferably, the laser ablation treatment time is 5-30s.

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