Organic matter in-situ testing method and application thereof

Abstract

The invention relates to an organic matter in-situ testing method and application thereof. The testing method comprises the following steps: adding an object to be tested into a reaction kettle with an optical window; aligning a spectrograph with an optical window of the reaction kettle, and calibrating a light path; and spectrum acquisition is carried out through a spectrograph. According to the test method, in-situ detection after hydrocarbon generation of the hydrocarbon source rock can be realized, and uncertainty of research caused by heterogeneity of parallel samples of the hydrocarbon source rock in a conventional simulation experiment is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of geochemistry and relates to an organic matter in-situ testing method and application thereof. Background Art

[0002] As natural gas exploration continues to expand into deep, ultra-deep, deepwater, unconventional and other fields, the exploration objects are becoming increasingly complex. The existing natural gas geological theory can no longer meet the needs of current natural gas exploration. It is necessary to continuously improve the existing basic natural gas geological theory to guide natural gas exploration and discover more large gas fields. Therefore, conducting research on the basic theory of natural gas is of great significance for improving and developing the existing basic natural gas geological theory and ensuring the continuous, rapid and efficient development of natural gas exploration in my country. The maturity of organic matter has an important impact on natural gas generation and is a common concern in the petroleum industry and natural gas accumulation.

[0003] The current thermal simulation technology mainly includes conventional autoclave simulation technology and gold tube thermal simulation technology, etc., which mainly uses parallel samples of source rocks or kerogen for thermal simulation experiments, and the heating temperature can reach up to 600-800℃. The temperature is still not high enough for the study of the generation and preservation of late natural gas. In addition, in the past, the thermal evolution simulation experiment of source rocks was mainly carried out by using multiple groups of parallel samples. The heterogeneity of organic matter in source rocks is strong and widespread, which is not conducive to the accurate evaluation of thermal evolution laws.

[0004] In order to solve the qualitative and quantitative evaluation of the effects of heterogeneity and temperature on hydrocarbon generation from organic matter, a method for studying the thermal evolution of kerogen under in situ conditions was invented. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide an organic matter in-situ testing method and application thereof.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an organic matter in-situ testing method, the testing method comprising:

[0008] (1) Add the test substance into a reaction vessel with an optical window;

[0009] (2) Align the spectrometer with the optical window of the reactor and calibrate the optical path;

[0010] (3) Collect spectra using a spectrometer.

[0011] The present invention can study the evolution law of pyrolysis components of organic matter with maturity under in-situ conditions. The test temperature can reach 1300°C, which is 500°C higher than the highest temperature of existing oil and gas simulation experiments, making up for the high degree of evolution of source rocks in deep oil and gas exploration, and the indoor simulation temperature cannot cover the whole process evolution stage. The hydrocarbon generation evolution stage of the whole process of organic matter can be studied without replacing or moving samples. The method is simple and has strong versatility. In addition, in-situ detection of source rocks after hydrocarbon generation can be realized, avoiding the uncertainty brought to the research by the heterogeneity of parallel samples of source rocks in conventional simulation experiments. It provides a new research method for the research in the fields of oil and gas accumulation and geochemistry. Through the technology of the present invention, the composition changes of organic matter under in-situ conditions can be accurately and quickly obtained, and the changes in functional group structure can be obtained, so as to explore the changes in composition and maturity during the pyrolysis of organic matter, and provide a strong scientific basis for the hydrocarbon generation problem of organic matter that is generally concerned in oil and gas exploration.

[0012] Preferably, the spectrometer in step (2) is any one of an infrared spectrometer, a laser differential Raman spectrometer or a laser induced breakdown spectrometer, or a combination of at least two of them.

[0013] Preferably, the spectrometer in step (2) is an infrared spectrometer and a laser differential Raman spectrometer.

[0014] Infrared and Raman spectroscopy were used to test the samples respectively to study the changes in the functional group structure of organic matter under in-situ pyrolysis conditions and its evolution with temperature.

[0015] Preferably, the spectrometer in step (2) is an infrared spectrometer or a laser induced breakdown spectrometer.

[0016] Infrared and laser induced breakdown spectroscopy were used to test the samples respectively to study the composition changes of organic matter under in-situ pyrolysis conditions and its evolution with temperature.

[0017] Preferably, the added amount of the analyte is 1-100 mg, for example, 1 mg, 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 35 mg, 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, etc. Other specific point values ​​within the above numerical range can be selected, which will not be described one by one here.

[0018] Preferably, the temperature of the reactor in step (2) is 25-1300°C, for example 25°C, 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, etc. Other specific point values ​​within the above numerical range can be selected, which will not be repeated here.

[0019] Preferably, the pressure of the reactor in step (2) is 0.1-5 MPa, for example 0.1 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, etc. Other specific point values ​​within the above numerical range can be selected and will not be described here one by one.

[0020] Preferably, the processing time of the infrared spectrometer for the object to be measured is 1-600s, for example, 1s, 50s, 100s, 150s, 200s, 250s, 300s, 350s, 400s, 450s, 500s, 550s, 600s, etc. Other specific point values ​​within the above numerical range can be selected, and they will not be described one by one here.

[0021] Preferably, the processing time of the laser differential Raman spectrometer for the object to be measured is 0.5-120s, for example 0.5s, 1s, 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, etc. Other specific point values ​​within the above numerical range can be selected, which will not be described one by one here.

[0022] Preferably, the processing time of the laser induced breakdown spectrometer for the object to be measured is 0.2-300s, for example 0.2s, 1s, 20s, 40s, 60s, 80s, 100s, 120s, 140s, 160s, 180s, 200s, 220s, 240s, 260s, 280s, 300s, etc. Other specific point values ​​within the above numerical range can be selected, which will not be described one by one here.

[0023] In a second aspect, the present invention provides an application of the in-situ testing method for organic matter according to the first aspect in detecting changes in the structure of functional groups under in-situ pyrolysis conditions of organic matter.

[0024] In a third aspect, the present invention provides an application of the in-situ testing method for organic matter according to the first aspect in detecting changes in the composition of organic matter under in-situ pyrolysis conditions.

[0025] In a fourth aspect, the present invention provides an application of the in-situ testing method for organic matter according to the first aspect in detecting the maturity of organic matter.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention can study the evolution law of the pyrolysis components of organic matter with maturity under in-situ conditions. The test temperature can reach 1300°C, which is 500°C higher than the highest temperature of the existing oil and gas simulation experiment, making up for the high degree of evolution of source rocks in deep oil and gas exploration, and the indoor simulation temperature cannot cover the whole process evolution stage. The hydrocarbon generation evolution stage of the whole process of organic matter can be studied, and the method is simple and versatile. In-situ detection after hydrocarbon generation of source rocks can be realized, avoiding the uncertainty brought to the research by the heterogeneity of parallel samples of source rocks in conventional simulation experiments. It provides a new research means for the research in the field of oil and gas accumulation and geochemistry. Through the technology of the present invention, the composition changes of organic matter under in-situ conditions can be accurately and quickly obtained, and the changes in functional group structure can be obtained, so as to explore the changes in composition and maturity during the pyrolysis of organic matter, and provide a strong scientific basis for the hydrocarbon generation problem of organic matter that is generally concerned in oil and gas exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the in-situ testing device.

[0029] Figure 2 This is the laser component spectrum of kerogen tested at room temperature in Example 1, wherein Figure a is the laser component spectrum of kerogen at room temperature, Figure b is the laser spectrum line of residual kerogen component at 300°C, Figure c is the laser spectrum line of residual kerogen component at 350°C, Figure d is the laser spectrum line of residual kerogen component at 400°C, Figure e is the laser spectrum line of residual kerogen component at 450°C, Figure f is the laser spectrum line of residual kerogen component at 500°C, and Figure g is the laser spectrum line of residual kerogen component at 500°C.

[0030] Figure 3 It is a line graph showing the changes in kerogen components with temperature under in-situ heating conditions.

[0031] Figure 4 This is the infrared spectrum result of in-situ heating of Triassic coal. DETAILED DESCRIPTION

[0032] 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.

[0033] The schematic diagram of the in-situ test device is as follows: Figure 1 shown.

[0034] Example 1

[0035] (1) 12 mg of kerogen prepared from low-maturity Xiamaling Formation mudstone was added into a reactor, and the reactor was sealed;

[0036] (2) The temperature of the reactor was set to 300°C and the pressure was set to 0.5 MPa. After the reactor reached the set temperature and pressure, the infrared spectrometer and the laser induced breakdown spectrometer were turned on respectively, and the light was aimed at the optical window of the reactor. The optical path was calibrated using standard substances, and the tests were performed respectively;

[0037] (3) Spectral collection of kerogen at the required temperature of 300-550°C and pressure of 0.5 MPa to obtain in-situ spectra of kerogen after hydrocarbon generation at different temperatures and pressures;

[0038] (4) After the test is completed, turn off the spectrum, wait until the temperature reaches room temperature and the pressure drops to normal pressure, open the reactor, take out the sample, and clean the reactor. After completion, wait for the next use.

[0039] Test results such as Figure 2 and Figure 3 As shown, Figure 2 is the laser spectrum of kerogen composition at different temperatures, Figure 3 This is a line graph showing the changes in kerogen components with temperature under in-situ heating conditions. Figure 3 It can be seen that under the conditions of in-situ heating, the spectral line intensity of the O element first shows a downward trend, and then there is a small increase at 350℃ to 400℃, then it decreases, and finally rises to a basically stable state; the spectral line intensity of the H element does not change significantly with temperature, and the content is basically stable. When heated to 550℃, the content decreases less than that at room temperature; the spectral line intensity of the N element changes with temperature only more significantly than that of the H element, and the final content decreases less; the spectral line intensity of the C element increases greatly with temperature and is in a state of continuous increase. This result shows that carbonization occurs in the kerogen during the heating process.

[0040] Example 2

[0041] (1) 10 mg of Tarim Basin Triassic coal was added into a reactor, and the reactor was sealed;

[0042] (2) The temperature of the reactor is set to 300°C and the pressure is set to 1 MPa. When the reactor reaches the set temperature and pressure, the infrared spectrometer and the laser differential Raman spectrometer are turned on respectively and the light is directed to the optical window of the reactor. The optical path is calibrated using standard substances and the tests are performed respectively.

[0043] (3) Collecting the spectrum of coal at the required temperature of 300-550°C and pressure of 1 MPa to obtain the in-situ spectrum of coal at different temperatures and pressures;

[0044] (4) After the test is completed, turn off the spectrum, wait until the temperature reaches room temperature and the pressure drops to normal pressure, open the reactor, take out the sample, and clean the reactor. After completion, wait for the next use.

[0045] The in-situ test results of Triassic coal are as follows Figure 4 As shown in the figure, the main functional groups of kerogen are -OH, CH, C=O, C=C, CO, and aromatic ring CH. As the temperature increases, CH gradually disappears, the peak intensities of C=C and C=O increase slightly first and then weaken, and CO shows an overall trend of first increasing and then decreasing, reaching a maximum value at 450°C. This temperature matches the pyrolysis temperature range corresponding to thermogravimetric analysis.

[0046] Example 3

[0047] (1) 15 mg of low-mature mudstone sample from the Fengcheng Formation in the Junggar Basin was added into a reactor, and the reactor was sealed;

[0048] (2) The temperature of the reactor is set to 450°C and the pressure is set to 0.7 MPa. When the reactor reaches the set temperature and pressure, the laser-induced breakdown spectroscopy is turned on and the light is directed to the optical window of the reactor, and the optical path is calibrated using standard substances.

[0049] (3) Spectra of mudstone samples at the required temperature of 450-750°C and pressure of 0.7 MPa are collected to obtain in situ laser induced breakdown spectra of mudstone samples at different temperatures and pressures.

[0050] (4) After the test is completed, turn off the spectrum, wait until the temperature reaches room temperature and the pressure drops to normal pressure, open the reactor, take out the sample, and clean the reactor. After completion, wait for the next use.

[0051] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate an in-situ testing method for organic matter and its application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0052] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0053] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. An organic matter in-situ testing method, characterized in that: The test method includes: (1) Add the test substance into a reaction vessel with an optical window; (2) Align the spectrometer with the optical window of the reactor and calibrate the optical path; (3) Collect spectra using a spectrometer.

2. The organic matter in-situ testing method according to claim 1, characterized in that: The spectrometer in step (2) is an infrared spectrometer and a laser differential Raman spectrometer.

3. The organic matter in-situ testing method according to claim 1, characterized in that: The spectrometer in step (2) is an infrared spectrometer and a laser induced breakdown spectrometer.

4. The organic matter in-situ testing method according to any one of claims 1 to 3, characterized in that: The added amount of the test substance is 1-100 mg.

5. The organic matter in-situ testing method according to any one of claims 1 to 4, characterized in that: The temperature of the reactor in step (2) is 25-1300°C.

6. The organic matter in-situ testing method according to any one of claims 1 to 5, characterized in that: The pressure of the reactor in step (2) is 0.1-5 MPa.

7. The organic matter in-situ testing method according to any one of claims 1 to 6, characterized in that: The processing time of the infrared spectrometer for the object to be measured is 1-600s; Preferably, the laser differential Raman spectrometer processes the object to be measured for a time period of 0.5-120 s; Preferably, the laser induced breakdown spectrometer processes the object to be measured for a time period of 0.2-300 s.

8. Use of the organic matter in-situ testing method according to any one of claims 1 to 7 in detecting changes in the functional group structure of organic matter under in-situ pyrolysis conditions.

9. Use of the organic matter in-situ testing method according to any one of claims 1 to 7 in detecting changes in the composition of organic matter under in-situ pyrolysis conditions.

10. Use of the organic matter in-situ testing method according to any one of claims 1 to 7 in detecting the maturity of organic matter.

Images