Method for judging true and false organic matter holes of shale through electron beam bombardment and application

Abstract

The invention discloses a method for judging true and false organic matter holes of shale by electron beam bombardment, which comprises the following steps: (1) preparing a shale sample; (2) carrying out polishing treatment on the shale sample; (3) observing the shale sample under a low vacuum degree, and searching organic matters with pores; and (4) bombarding the organic matter with pores by electron beams, and judging whether the organic matter pores are true or false. The invention further discloses application of the method for judging true and false organic matter holes of shale through electron beam bombardment to judgment of mobility of crude oil. According to the method, the authenticity of organic matter holes in shale and the mobility of shale oil can be judged and identified qualitatively under the condition of existing common instruments and equipment at home and abroad, so that a foundation is laid for researching the reservoir space type of a shale reservoir and the proportion of various reservoir spaces; and technical support is further provided for shale oil area selection and zone selection, exploration target determination and horizontal well target layer determination.

Description

Technical Field

[0001] The present invention belongs to the field of shale reservoir characterization and oil and gas exploration, and particularly relates to a method for identifying true and false organic matter pores in shale by electron beam bombardment and its application. Background Art

[0002] Organic matter pores are developed in both marine and continental shales and are an important type of reservoir space in shale reservoirs. In most Paleozoic marine shales, organic matter pores are the main storage space for methane gas, and their content is an important basis for judging the quality of gas-bearing shale reservoirs.

[0003] Previous studies on marine shales in North America have shown that organic matter pores are controlled by maturity. When the vitrinite reflectance Ro is greater than 0.9%, organic matter enters the gas generation stage, and the gas volume expands, resulting in the generation of organic matter pores. When the vitrinite reflectance Ro is less than 0.9%, organic matter pores are basically not developed.

[0004] In recent years, domestic and foreign scholars have also found a large number of organic matter pores in shales with a vitrinite reflectance Ro of 0.6%-0.8%. These pores are mainly controlled by the type of organic matter, and it is believed that type I kerogen and type II kerogen with a higher content of sapropel can generate organic matter pores at low maturity.

[0005] The above understandings were obtained by domestic and foreign scholars through a large number of scanning electron microscope observations of shale samples from different regions. For example, Chinese Patent Application CN 110726655A discloses an experimental method for simulating the evolution process of organic pores in mud shale, which includes the following steps: Step 1: Collect immature-low mature mud shale samples, cut them into multiple mud shale blocks and polish them; Step 2: Determine the simulation temperature, pressure, and time; Step 3: Load quartz sand into the sample chamber and then load the mud shale blocks in sequence; Step 4: Conduct a thermal simulation experiment on the hydrocarbon generation evolution of mud shale in the low evolution stage; Step 5: Take out the mud shale blocks, mechanically polish a part of them and etch the sample surface, and measure the vitrinite reflectance of one block according to the "SY / T5124-2012 Determination Method of Vitrinite Reflectance in Sedimentary Rocks"; Step 6: Repeat Step 3 and Step 5; Step 7: Repeat Step 6 until all the set evolution stages are completed.

[0006] At present, the research on organic matter pores in shale mainly relies on argon ion polishing - field emission scanning electron microscopy technology. By using scanning electron microscopy under low - vacuum or high - vacuum conditions, when pores are observed inside the organic matter, these pores are classified as organic matter pores. For example, Chinese Patent Application CN109916937A discloses an analysis method for the maturity of shale organic matter, which includes the following steps: Step 100, sample preparation: mechanically polish and argon ion polish the shale sample; Step 200, analyze the pore structure of shale quasi - in - situ organic matter and the characteristics of laser Raman spectroscopy respectively using a thermal field emission scanning electron microscope and a laser Raman spectrometer, and introduce a correction factor to correct the obtained laser Raman spectroscopy characteristics according to the characteristics of the pore structure of shale quasi - in - situ organic matter; Step 300, calculate the maturity of organic matter in different occurrence states in the shale sample. By using field emission scanning electron microscopy and laser Raman spectroscopy analysis as research means, analyze the occurrence state of organic matter and the degree of pore development in the shale, obtain the laser Raman spectroscopy characteristics and parameters of organic matter in different occurrence states, and directly calculate the thermal evolution maturity of organic matter in different occurrence states with reference to the thermal evolution maturity calculation formula.

[0007] However, the current experimental observation method has great defects. The main reason is that it is impossible to guarantee the original formation temperature and pressure conditions during observation. Under the change of temperature and pressure conditions, the observed organic matter pores may not be real.

[0008] Existing domestic and foreign instrument and equipment conditions do not yet have the ability to observe organic matter pores under the original temperature and pressure. Therefore, there is an urgent need to establish a method for identifying organic matter pores under the current equipment technology conditions. Summary of the Invention

[0009] Object of the Invention: Aiming at the deficiencies of the above - mentioned existing technologies, through a large number of argon ion polishing - field emission scanning electron microscopy observation experiments on shale samples, the inventor proposes a method for identifying true and false organic matter pores in shale by bombarding with an electron beam. On this basis, the mobility of crude oil can be further qualitatively identified.

[0010] Technical Solution: A method for identifying true and false organic matter pores in shale by bombarding with an electron beam, the steps are as follows:

[0011] (1), Prepare a shale sample;

[0012] (2), Polish the shale sample;

[0013] (3), Observe the shale sample under low vacuum to find organic matter with pores;

[0014] (4), Bombard the organic matter with pores with an electron beam to identify the true and false of the organic matter pores.

[0015] Further, the specific steps of step (1) are as follows:

[0016] Use a rock cutting machine to cut out a block-shaped shale sample from the inside of a shale saw blade, where:

[0017] The top surface area of the shale sample is 0.5 cm 2 -2 cm 2 and the thickness ≤ 1 cm.

[0018] Furthermore, the grit size of the shale saw blade is 30 μm - 35 μm.

[0019] Further, the specific steps of step (2) are as follows:

[0020] (21), Grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample, then stick the shale sample onto a sample post, and then place the sample post into a cutting and grinding integrated machine;

[0021] (22), Keep the saw blade parallel to the surface of the sample post, and then cut the surface to be polished of the shale sample. After cutting, the surface to be polished of the shale sample is nearly parallel to the surface of the sample post;

[0022] (23), Grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample processed in step (2), then grind off at least 30 μm from the surface to be polished of the shale sample, and finally grind off at least 18 μm from the surface to be polished of the shale sample;

[0023] (24), Place the shale sample processed in step (23) into an argon ion polishing instrument for polishing for 2 h - 4 h.

[0024] Furthermore, in step (21), use a polishing paper with a grit size of 10 - 20 μm to grind off 65 μm - 100 μm from the opposite side of the surface to be polished of the shale sample, then stick the shale sample onto a sample post, and then place the sample post into a cutting and grinding integrated machine.

[0025] Furthermore, in step (22), the grit size of the saw blade used for cutting is 30 μm - 35 μm.

[0026] Furthermore, in step (23), use a polishing paper with a grit size of 10 - 20 μm to grind off 65 μm - 100 μm from the opposite side of the surface to be polished of the shale sample processed in step (2), then use a polishing paper with a grit size of 8 - 12 μm to grind off 30 - 45 μm from the surface to be polished of the shale sample, and finally use a polishing paper with a grit size of 1 - 3 μm to grind off 18 - 27 μm from the surface to be polished of the shale sample.

[0027] Furthermore, in step (24), during polishing, dissipate heat once every 20 - 40 minutes.

[0028] Further, the specific steps of step (3) are as follows:

[0029] (31) Set the scanning electron microscope experimental parameters (acceleration voltage 10 kV, sample chamber pressure 60 Pa);

[0030] (32) Use the backscattered electron probe of the scanning electron microscope to collect signals, focus on and observe the surface of the shale sample, and search for organic matter (organic matter appears as a lower gray scale in the backscattered image, but is brighter than pores, and the gray scale is between rock mineral particles and pores);

[0031] (33) Search for organic matter with pores among the organic matter found in step (32).

[0032] Further, the specific steps of step (4) are as follows:

[0033] (41) Adjust the organic matter with pores found to the middle of the scanning electron microscope field of view, switch the backscattered electron probe of the scanning electron microscope to a secondary electron probe, magnify it more than 10,000 times, and adjust the focal length to make the organic matter clearly visible;

[0034] (42) Connect the energy spectrometer, bombard the organic matter with pores using the energy spectrum electron beam, collect the energy spectrum information, observe the energy spectrum pattern, and if the C peak is higher, it indicates that the observed is organic matter;

[0035] (43) Continuously refresh the secondary electron real-time image and observe the electron beam bombardment position, where:

[0036] If pores appear at the bombardment position, continuously become larger or deformed, and the previously observed pores also deform, it indicates that the organic matter is in a liquid state, and the generation of pores is caused by the shrinkage or degassing of asphalt after the reduction of surface pressure. The bombardment of the electron beam causes the asphaltene (crude oil) to deform and produce pits, indicating that there are no pores inside the organic matter under formation conditions, and the observed organic matter pores are false organic matter pores;

[0037] If there is no obvious change at the position bombarded by the electron beam and the morphology of the previously observed pores does not change, it indicates that the observed organic matter pores are true organic matter pores.

[0038] The method of using electron beam bombardment to identify true and false organic matter pores in shale as described above is used as an application for judging the mobility of crude oil.

[0039] Further, the specific steps of the above application are as follows:

[0040] (51) If it is determined in step (4) that the organic matter is crude oil, first observe the development degree of the pores inside the crude oil. A high development degree of the pores indicates a large original gas content in the crude oil, and the better the mobility of the crude oil under formation conditions, and vice versa;

[0041] (52) Bombard the crude oil with an energy spectrum electron beam, observe the change of the pit at the bombardment position, bombard the crude oil in different samples at the same magnification, observe again after the same time interval A after bombardment, compare the sizes of the pits, the larger the pit, the better the mobility of the crude oil, and vice versa.

[0042] (53) For the organic matter without pores observed on the surface, bombard the crude oil with an energy spectrum electron beam, observe the change of the pit at the bombardment position, bombard the crude oil in different samples at the same magnification, observe again after the same time interval A after bombardment, compare the sizes of the pits, the larger the pit, the better the mobility of the crude oil, and vice versa.

[0043] Furthermore, the time A is 5 seconds - 10 seconds.

[0044] Invention effect: A method and application for identifying true and false organic matter pores in shale by electron beam bombardment disclosed by the present invention have the following beneficial effects:

[0045] The present invention can identify the true and false of organic matter pores in shale and qualitatively identify the mobility of shale oil under the conditions of relatively common existing instrument and equipment at home and abroad, lay a foundation for studying the types of reservoir spaces and the proportion of various reservoir spaces in shale reservoirs, and further provide technical support for shale oil selection area and zone, determining exploration targets and horizontal well target layers. Description of the drawings

[0046] Figure 1 It is a flow chart of a method for identifying true and false organic matter pores in shale by electron beam bombardment disclosed by the present invention.

[0047] Figure 2a and Figure 2b It is a schematic diagram of the change before and after electron beam bombardment of organic matter with pores in Example 1.

[0048] Figure 3a 、 Figure 3b 、 Figure 3c It is a schematic diagram of the change after energy spectrum electron beam bombardment of crude oil with different mobilities in Example 1. Among them: A1, A2, A3, A4, A5 represent the electron beam bombardment positions. Detailed description of the specific implementation mode

[0049] The following is a detailed description of the specific implementation mode of the present invention.

[0050] Example 1

[0051] A method for identifying true and false organic matter pores in shale by electron beam bombardment is as follows:

[0052] (1) Prepare shale samples;

[0053] (2), polish the shale sample;

[0054] (3), observe the shale sample under low vacuum to find organic matter with pores;

[0055] (4), bombard the organic matter with pores with an electron beam to identify the authenticity of the pores in the organic matter.

[0056] Further, the specific steps of step (1) are as follows:

[0057] Use a rock cutting machine to cut out a block of shale sample from the inside of the shale saw blade, where:

[0058] The top surface area of the shale sample is 1 cm 2 , and the thickness is 0.8 cm.

[0059] Furthermore, the grit size of the shale saw blade is 32 μm.

[0060] Further, the specific steps of step (2) are as follows:

[0061] (21), grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample, then stick the shale sample on the sample post, and then put the sample post into the cutting and grinding machine;

[0062] (22), keep the saw blade parallel to the surface of the sample post, and then cut the surface to be polished of the shale sample. After cutting, the surface to be polished of the shale sample is nearly parallel to the surface of the sample post;

[0063] (23), grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample processed in step (2), then grind off at least 30 μm from the surface to be polished of the shale sample, and finally grind off at least 18 μm from the surface to be polished of the shale sample;

[0064] (24), put the shale sample processed in step (23) into an argon ion polishing instrument for polishing for 2 h - 4 h.

[0065] Furthermore, in step (21), use a polishing sandpaper with a grit size of 15 μm to grind off 80 μm from the opposite side of the surface to be polished of the shale sample, then stick the shale sample on the sample post, and then put the sample post into the cutting and grinding machine.

[0066] Furthermore, the grit size of the saw blade used for cutting in step (22) is 32 μm.

[0067] Further, in step (23), use a polishing paper with a grit size of 15 μm to grind off 80 μm from the opposite side of the surface to be polished of the shale sample processed in step (2), then use a polishing paper with a grit size of 8 - 12 μm to grind off 40 μm from the surface to be polished of the shale sample, and finally use a polishing paper with a grit size of 2 μm to grind off 24 μm from the surface to be polished of the shale sample.

[0068] Further, in step (24), during polishing, dissipate heat once every 30 minutes.

[0069] Further, the specific steps of step (3) are as follows:

[0070] (31) Set the scanning electron microscope experimental parameters (acceleration voltage 10 kV, sample chamber pressure 60 Pa);

[0071] (32) Use the backscattered electron probe of the scanning electron microscope to collect signals, focus on and observe the surface of the shale sample, and search for organic matter (organic matter appears as a lower gray scale in the backscattered image, but is brighter than pores, and the gray scale is between rock mineral particles and pores);

[0072] (33) Search for organic matter with pores among the organic matter found in step (32).

[0073] Further, the specific steps of step (4) are as follows:

[0074] (41) Adjust the organic matter with pores found to the middle of the scanning electron microscope field of view, switch the backscattered electron probe of the scanning electron microscope to a secondary electron probe, magnify to more than 10,000 times, and adjust the focal length to make the organic matter clearly visible;

[0075] (42) Connect the energy spectrometer, use the energy spectrum electron beam to bombard the organic matter with pores, collect the energy spectrum information, observe the energy spectrum spectrogram, and a higher C peak indicates that the observed is organic matter;

[0076] (43) Continuously refresh the secondary electron real - time image, observe the electron beam bombardment position, where:

[0077] Figure 2a and Figure 2b are schematic diagrams of the changes before and after the electron beam bombards the organic matter with pores in Example 1. As Figure 2a and Figure 2b shown, pores appear at the bombardment position, and continuously become larger or deformed, and the previously observed pores also deform, indicating that the organic matter is in a liquid state. The generation of pores is caused by the shrinkage or degassing of asphalt after the surface pressure decreases. The bombardment of the electron beam causes the asphaltene (crude oil) to deform and produce pits, indicating that there are no pores inside the organic matter under formation conditions, and the observed organic matter pores are pseudo - organic matter pores;

[0078] If the position bombarded by the electron beam does not change significantly and the previously observed pore morphology also remains unchanged, it indicates that the observed organic matter pores are true organic matter pores.

[0079] The method for identifying true and false organic matter pores in shale by bombarding with an electron beam as described in any one of the above is used as an application for judging the mobility of crude oil.

[0080] Furthermore, the specific steps of the application are as follows:

[0081] (51) If it is determined in step (4) that the organic matter is crude oil, first observe the development degree of the pores inside the crude oil. A high development degree of the pores indicates a large original gas content in the crude oil and better mobility of the crude oil under formation conditions, and vice versa.

[0082] (52) Bombard the crude oil with an energy spectrum electron beam, observe the change of the pit at the bombarded position, bombard the crude oil in different samples at the same magnification, and observe again after the same time interval A after bombardment. Compare the sizes of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa.

[0083] (53) For the organic matter without pores observed on the surface, bombard the crude oil with an energy spectrum electron beam, observe the change of the pit at the bombarded position, bombard the crude oil in different samples at the same magnification, and observe again after the same time interval A after bombardment. Compare the sizes of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa.

[0084] Even further, the time A is 8 seconds.

[0085] Figure 3a 、 Figure 3b 、 Figure 3c It is a schematic diagram of the changes after energy spectrum electron beam bombardment of crude oils with different mobilities in Example 1. Among them: Figure 3a It is the case where the mobility of the crude oil is relatively strong; Figure 3b It is the case where the mobility of the crude oil is relatively medium; Figure 3c It is the case where the mobility of the crude oil is relatively poor.

[0086] Example 2

[0087] A method for identifying true and false organic matter pores in shale by bombarding with an electron beam, the steps are as follows:

[0088] (1) Prepare a shale sample;

[0089] (2) Polish the shale sample;

[0090] (3) Observe the shale sample under low vacuum to find organic matter with pores;

[0091] (4) Bombard the organic matter with pores by an electron beam to identify the authenticity of the pores in the organic matter.

[0092] Further, the specific steps of step (1) are as follows:

[0093] Use a rock cutting machine to cut out a block-shaped shale sample from the inside of the shale saw blade, where:

[0094] The top surface area of the shale sample is 0.5 cm 2 and the thickness is 0.5 cm.

[0095] Furthermore, the grit size of the shale saw blade is 30 μm.

[0096] Further, the specific steps of step (2) are as follows:

[0097] (21) Grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample, then stick the shale sample onto the sample post, and then place the sample post into a cutting and grinding integrated machine;

[0098] (22) Keep the saw blade parallel to the surface of the sample post, and then cut the surface to be polished of the shale sample. After cutting, the surface to be polished of the shale sample is nearly parallel to the surface of the sample post;

[0099] (23) Grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample processed in step (2), then grind off at least 30 μm from the surface to be polished of the shale sample, and finally grind off at least 18 μm from the surface to be polished of the shale sample;

[0100] (24) Place the shale sample processed in step (23) into an argon ion polishing instrument for polishing for 2 h.

[0101] Furthermore, in step (21), use a polishing sandpaper with a grit size of 10 μm to grind off 65 μm from the opposite side of the surface to be polished of the shale sample, then stick the shale sample onto the sample post, and then place the sample post into a cutting and grinding integrated machine.

[0102] Furthermore, the grit size of the saw blade used for cutting in step (22) is 30 μm.

[0103] Furthermore, in step (23), use a polishing sandpaper with a grit size of 10 μm to grind off 65 μm from the opposite side of the surface to be polished of the shale sample processed in step (2), then use an 8-μm polishing sandpaper to grind off 30 μm from the surface to be polished of the shale sample, and finally use a polishing sandpaper with a grit size of 1 μm to grind off 18 μm from the surface to be polished of the shale sample.

[0104] Furthermore, in step (24), during polishing, dissipate heat once every 20 minutes.

[0105] Furthermore, the specific steps of step (3) are as follows:

[0106] (31) Set the scanning electron microscope experimental parameters (acceleration voltage 10 kV, sample chamber pressure 60 Pa);

[0107] (32) Use the backscattered probe of the scanning electron microscope to collect signals, focus on and observe the surface of the shale sample to find organic matter (organic matter appears as a lower gray scale in the backscattered image, but is brighter than pores, and the gray scale is between rock mineral particles and pores);

[0108] (33) Find the organic matter with pores among the organic matter found in step (32).

[0109] Furthermore, the specific steps of step (4) are as follows:

[0110] (41) Adjust the organic matter with pores found to the middle of the scanning electron microscope field of view, switch the backscattered probe of the scanning electron microscope to a secondary electron probe, magnify it more than 10,000 times, and adjust the focal length to make the organic matter clearly visible;

[0111] (42) Connect the energy spectrometer, use the energy spectrum electron beam to bombard the organic matter with pores, collect the energy spectrum information, observe the energy spectrum pattern, and if the C peak is higher, it indicates that the observed is organic matter;

[0112] (43) Continuously refresh the secondary electron real-time image and observe the electron beam bombardment position, where:

[0113] If pores appear at the bombardment position, and they continuously become larger or deformed, and the previously observed pores are also deformed, it indicates that the organic matter is in a liquid state, and the generation of pores is caused by the shrinkage or degassing of asphalt after the reduction of surface pressure. The bombardment of the electron beam causes the asphaltene (crude oil) to deform and produce pits, indicating that there are no pores inside the organic matter under formation conditions, and the observed organic matter pores are pseudo-organic matter pores;

[0114] If there is no obvious change at the position bombarded by the electron beam, and the morphology of the previously observed pores has not changed, it indicates that the observed organic matter pores are true organic matter pores.

[0115] The method of using electron beam bombardment to identify true and false organic matter pores in shale as described above is applied to judge the mobility of crude oil.

[0116] Furthermore, the specific steps of the above application are as follows:

[0117] (51) If it is determined in step (4) that the organic matter is crude oil, first observe the development degree of the pores inside the crude oil. A high development degree of pores indicates a large original gas content in the crude oil, and the better the mobility of the crude oil under formation conditions, and vice versa.

[0118] (52) Bombard the crude oil with an energy spectrum electron beam, observe the change of the pit at the bombardment position, bombard the crude oil in different samples at the same magnification, observe again after the same time interval A after bombardment, and compare the sizes of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa.

[0119] (53) For the organic matter with no pores observed on the surface, bombard the crude oil with an energy spectrum electron beam, observe the change of the pit at the bombardment position, bombard the crude oil in different samples at the same magnification, observe again after the same time interval A after bombardment, and compare the sizes of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa.

[0120] Furthermore, the time A is 5 seconds.

[0121] Example 3

[0122] A method for identifying true and false organic matter pores in shale by using electron beam bombardment, the steps are as follows:

[0123] (1) Prepare a shale sample;

[0124] (2) Polish the shale sample;

[0125] (3) Observe the shale sample under low vacuum to find the organic matter with pores;

[0126] (4) Bombard the organic matter with pores with an electron beam to identify the true and false of the organic matter pores.

[0127] Further, the specific steps of step (1) are as follows:

[0128] Use a rock cutting machine to cut out a block-shaped shale sample from the inside of the shale saw blade, where:

[0129] The top surface area of the shale sample is 2 cm 2 and the thickness is 1 cm.

[0130] Furthermore, the grit size of the shale saw blade is 35 μm.

[0131] Further, the specific steps of step (2) are as follows:

[0132] (21) Grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample, then stick the shale sample on the sample stub, and then put the sample stub into the cutting and grinding machine;

[0133] (22) Keep the saw blade parallel to the surface of the sample stub, and then cut the surface to be polished of the shale sample. After cutting, the surface to be polished of the shale sample is nearly parallel to the surface of the sample stub;

[0134] (23) Grind off at least 65 μm from the opposite side of the surface to be polished of the shale sample processed in step (2), then grind off at least 30 μm from the surface to be polished of the shale sample, and finally grind off at least 18 μm from the surface to be polished of the shale sample.

[0135] (24) Put the shale sample processed in step (23) into an argon ion polishing instrument for polishing for 2 h - 4 h.

[0136] Furthermore, in step (21), grind off 100 μm from the opposite side of the surface to be polished of the shale sample with a polishing sandpaper having a grit size of 20 μm, then stick the shale sample to a sample post, and then put the sample post into a cutting and grinding integrated machine.

[0137] Furthermore, in step (22), the grit size of the saw blade used for cutting is 30 μm - 35 μm.

[0138] Furthermore, in step (23), grind off 100 μm from the opposite side of the surface to be polished of the shale sample processed in step (2) with a polishing sandpaper having a grit size of 20 μm, then grind off 45 μm from the surface to be polished of the shale sample with a 12 - μm polishing sandpaper, and finally grind off 27 μm from the surface to be polished of the shale sample with a polishing sandpaper having a grit size of 3 μm.

[0139] Furthermore, in step (24), during polishing, dissipate heat once every 40 minutes.

[0140] Further, the specific steps of step (3) are as follows:

[0141] (31) Set the scanning electron microscope experiment parameters (acceleration voltage 10 kV, sample chamber pressure 60 Pa).

[0142] (32) Use the backscattered electron probe of the scanning electron microscope to collect signals, focus on and observe the surface of the shale sample, and search for organic matter (organic matter appears as a lower gray scale in the backscattered image, but is brighter than pores, and the gray scale is between rock mineral particles and pores).

[0143] (33) Search for organic matter with pores among the organic matter found in step (32).

[0144] Further, the specific steps of step (4) are as follows:

[0145] (41) Adjust the found organic matter with pores to the middle of the scanning electron microscope field of view, switch the backscattered electron probe of the scanning electron microscope to a secondary electron probe, magnify it to more than 10,000 times, and adjust the focal length to make the organic matter clearly visible.

[0146] (42) Connect an energy spectrometer, use the energy spectrum electron beam to bombard the organic matter with pores, collect the energy spectrum information, observe the energy spectrum pattern. A higher C peak indicates that the observed material is organic matter;

[0147] (43) Continuously refresh the secondary electron real-time image and observe the position bombarded by the electron beam. Among them:

[0148] If pores appear at the bombarded position, continuously expand or deform, and the previously observed pores also deform, it indicates that the organic matter is in a liquid state. The generation of pores is caused by the shrinkage or degassing of asphalt after the reduction of surface pressure. The bombardment of the electron beam causes the asphaltene (crude oil) to deform and produce pits, indicating that there are no pores inside the organic matter under formation conditions, and the observed organic matter pores are false organic matter pores;

[0149] If there is no obvious change at the position bombarded by the electron beam and the morphology of the previously observed pores does not change, it indicates that the observed organic matter pores are true organic matter pores.

[0150] The method of using electron beam bombardment to identify true and false organic matter pores in shale as described above is used as an application for judging the mobility of crude oil.

[0151] Further, the specific steps of the above application are as follows:

[0152] (51) If it is determined in step (4) that the organic matter is crude oil, first observe the development degree of the pores inside the crude oil. A high development degree of pores indicates a large original gas content in the crude oil, and the better the mobility of the crude oil under formation conditions, and vice versa;

[0153] (52) Conduct energy spectrum electron beam bombardment on the crude oil, observe the change of pits at the bombarded position. Bombard the crude oil in different samples at the same magnification, and then observe again after the same time interval A after bombardment. Compare the sizes of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa.

[0154] (53) For the organic matter without pores observed on the surface, conduct energy spectrum electron beam bombardment on the crude oil, observe the change of pits at the bombarded position. Bombard the crude oil in different samples at the same magnification, and then observe again after the same time interval A after bombardment. Compare the sizes of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa.

[0155] Even further, the time A is 10 seconds.

[0156] The above has made a detailed description of the embodiments of the present invention. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge scope of those of ordinary skill in the art.

Claims

1. A method for identifying true and false organic pores in shale using electron beam bombardment, characterized in that: Here are the steps: (1) Prepare shale samples; (2) polishing the shale sample; (3) observing the shale sample under low vacuum to find organic matter with pores; (4) Electron beam bombards organic matter with pores to determine whether the pores are genuine.

2. A method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 1, characterized in that: The specific steps of step (1) are as follows: The rock cutter is used to cut out block shale samples from the inside of the shale saw blade, wherein: The top surface area of ​​the shale sample is 0.5 cm 2 -2cm 2 , thickness ≤1cm.

3. A method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 2, characterized in that: The grit degree of the shale saw blade is 30 μm-35 μm.

4. The method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 1, characterized in that: The specific steps of step (2) are as follows: (21) grinding off at least 65 μm of the opposite side of the intended polishing surface of the shale sample, and then gluing the shale sample to a sample pile, and then placing the sample pile into a cutting and grinding machine; (22), keeping the saw blade parallel to the surface of the sample pile, and then cutting the intended polishing surface of the shale sample, so that the intended polishing surface of the shale sample after cutting is nearly parallel to the surface of the sample pile; (23) grinding off at least 65 μm of the opposite side of the intended polishing surface of the shale sample processed in step (2), then grinding off at least 30 μm of the intended polishing surface of the shale sample, and finally grinding off at least 18 μm of the intended polishing surface of the shale sample; (24) Place the shale sample treated in step (23) into an argon ion polisher for polishing for 2 h to 4 h.

5. The method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 4, characterized in that: In step (21), the opposite side of the intended polishing surface of the shale sample is ground off by 65 μm to 100 μm using sandpaper with a grit of 10 to 20 μm, and then the shale sample is glued to a sample pile, and then the sample pile is placed in a cutting and grinding machine.

6. The method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 4, characterized in that: The grit of the saw blade used for cutting in step (22) is 30 μm-35 μm.

7. The method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 4, characterized in that: In step (23), 65 μm to 100 μm of the opposite side of the intended polishing surface of the shale sample treated in step (2) is ground off with sandpaper having a grit of 10 to 20 μm, and then 30 to 45 μm of the intended polishing surface of the shale sample is ground off with sandpaper having a grit of 8 to 12 μm, and finally 18 to 27 μm of the intended polishing surface of the shale sample is ground off with sandpaper having a grit of 1 to 3 μm.

8. The method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 4, characterized in that: In step (24), during polishing, heat is dissipated every 20-40 minutes.

9. The method for identifying true and false organic pores in shale by electron beam bombardment as claimed in claim 1, characterized in that: The specific steps of step (3) are as follows: (31) Set the SEM experimental parameters; (32), collecting signals with a scanning electron microscope backscatter probe and focusing and observing the surface of the shale sample to search for organic matter; (33) Searching for organic matter with pores among the organic matter found in step (32).

10. The method for identifying true and false organic pores in shale by electron beam bombardment according to claim 1, characterized in that: The specific steps of step (4) are as follows: (41) Adjust the found organic matter with pores to the middle of the field of view of the scanning electron microscope, switch the backscatter probe of the scanning electron microscope to a secondary electron probe, magnify it to more than 10,000 times, and adjust the focus so that the organic matter is clearly visible; (42) Connect an energy spectrometer, use an energy spectrum electron beam to bombard the organic matter with pores, collect energy spectrum information, observe the energy spectrum, and the C peak is higher, indicating that what is observed is organic matter; (43) Continuously refresh the real-time image of secondary electrons and observe the electron beam bombardment position, where: If pores appear at the bombardment position and continue to grow or deform, and the previously observed pores are also deforming, it means that the organic matter is in liquid state. The pores are caused by the shrinkage or degassing of asphalt after the surface pressure is reduced. The bombardment of the electron beam causes the asphaltene to deform and produce pits, indicating that there are no pores inside the organic matter under the formation conditions, and the observed organic pores are pseudo-organic pores. If the position bombarded by the electron beam does not change significantly and the previously observed pore morphology does not change, it means that the observed organic pores are true organic pores.

11. Application of the method of any one of claims 1 to 10 for identifying true and false organic pores in shale by electron beam bombardment as a method for determining the mobility of crude oil.

12. The use according to claim 11, characterized in that The specific steps are as follows: (51) If the organic matter is determined to be crude oil in step (4), first observe the development degree of pores inside the crude oil. A high degree of pore development indicates a high original gas content of the crude oil and better mobility of the crude oil under formation conditions, and vice versa. (52) Bombard crude oil with an electron beam and observe the changes in the pits at the bombardment position. Bombard crude oil from different samples at the same magnification and observe again at the same interval A after the bombardment to compare the sizes of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa. (53) For organic matter with no pores on the surface, the crude oil was bombarded with an energy spectrum electron beam to observe the changes in the pits at the bombardment position. The crude oil in different samples was bombarded at the same magnification and observed again at the same time interval A after the bombardment to compare the size of the pits. The larger the pit, the better the mobility of the crude oil, and vice versa.

13. The use according to claim 12, characterized in that The time A is 5 seconds to 10 seconds.

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