GB2607836A - Method for determining change in nanoscale pore structure, and use thereof - Google Patents
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- 239000011148 porous material Substances 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 51
- 230000008859 change Effects 0.000 title claims abstract description 38
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 42
- 238000001179 sorption measurement Methods 0.000 claims abstract description 38
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 21
- 230000008569 process Effects 0.000 claims abstract description 11
- 238000009849 vacuum degassing Methods 0.000 claims abstract description 5
- 239000007788 liquid Substances 0.000 claims abstract description 4
- 238000003775 Density Functional Theory Methods 0.000 claims abstract description 3
- 238000010298 pulverizing process Methods 0.000 claims description 51
- 238000002360 preparation method Methods 0.000 claims description 12
- 239000011802 pulverized particle Substances 0.000 claims description 12
- 238000012512 characterization method Methods 0.000 claims description 11
- 239000007789 gas Substances 0.000 claims description 9
- 238000012360 testing method Methods 0.000 claims description 7
- 239000002356 single layer Substances 0.000 claims description 6
- 230000007423 decrease Effects 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 2
- 238000011160 research Methods 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 abstract 2
- 238000010586 diagram Methods 0.000 description 14
- 239000011435 rock Substances 0.000 description 13
- 206010017076 Fracture Diseases 0.000 description 12
- 208000010392 Bone Fractures Diseases 0.000 description 7
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000007872 degassing Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 239000003209 petroleum derivative Substances 0.000 description 2
- 208000013201 Stress fracture Diseases 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007619 statistical method Methods 0.000 description 1
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N15/088—Investigating volume, surface area, size or distribution of pores; Porosimetry
- G01N15/0893—Investigating volume, surface area, size or distribution of pores; Porosimetry by measuring weight or volume of sorbed fluid, e.g. B.E.T. method
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Abstract
Disclosed are a method for determining a change in a nanoscale pore structure, and the use thereof. The determination method comprises: a, putting a nanoscale pore structure sample which has been subjected to vacuum degassing into liquid nitrogen to obtain an isothermal adsorption curve, which shows the amount of nitrogen absorbed by the sample as the relative pressure P/P0 changes; b, according to the isothermal adsorption curve, calculating the specific surface area (SSA) of the sample by utilizing a BET specific surface area formula; c, according to an NLDFT density function theory method, obtaining the sum PV of pore volumes of pores of different scales in the sample; and d, determining the influence of a crushing process on the nanoscale pore structure according to an SSA/PV value following changes in a crushing mesh number. The determination method can accurately determine the influence of a sample fabrication damage process on the nanoscale pore structure of a tight reservoir, and can be used for determining the error influence, brought about by a change in a pore structure during sample fabrication, on a research result in a traditional tight reservoir nanoscale pore qualitative and quantitative research method.
Description
METHOD FOR DETERMINING CHANGE IN NANOSCALE PORE STRUCTURE AND
USE THEREOF
CROSS REFERENCE TO RELATED APPLICATION
[0001] This patent application claims the benefit and priority of Chinese Patent Application No. CN202010281035.2 filed on April 10, 2020, the disclosure of which is incorporated by reference herein in its entirety as part of the present application.
TECHNICAL FIELD
[0002] The present disclosure relates to a method for determining a change in a nanoscale pore structure and use thereof
BACKGROUND ART
[0003] With growing global energy demand and continually improving oil and gas exploitation technology, tight oil and gas resources have become the focus of exploration and exploitation in many countries. The occurrence and seepage of petroleum and natural gas mainly take place in the nanoscale pore and fracture system in tight reservoirs (e.g., shale cores obtained during drilling and extraction). Therefore, it is of great significance for the exploration and exploitation of tight oil and gas to carry out effective and reasonable evaluation and determination for the pore and fracture system of tight reservoirs.
[0004] A porous medium is composed of many pores and a solid matrix in which the pores develop. A specific surface area of a porous medium is the total area of the porous medium per unit of mass. A pore volume is the total volume of pores in a porous medium per unit of mass. A pore size distribution refers to percentages of different levels of pore sizes in a porous medium calculated by number or volume. Microscopic pores of a porous medium may be divided into micropores (<2 nm), mesopores (2-50 nm), and macropores (including pores and fractures of >50 nm). Existing experimental methods for pore characterization of a porous medium include a low temperature nitrogen adsorption method, a mercury intrusion method, etc. Principally, these methods may directly reflect some characteristics of microscopic pores in a porous medium by measured parameters such as the specific surface area, the pore volume and the pore size distribution. A tight reservoir is a porous medium. On the basis of the existing experimental methods for pore characterization, usually the characterization parameters of the microscopic pores in the tight reservoir may be measured under different under experimental conditions, such as different lithological characters, different mesh numbers, and different temperatures and pressures, and compared in transverse and longitudinal directions, thereby indirectly reflecting the influences of different experimental conditions on the microscopic pore structure of the tight reservoir. At present, some typical rock mechanical parameters, such as Young modulus and Poisson's ratio, are often used to evaluate the difficulty level of fracture development in a tight reservoir. However, the above-mentioned methods all overlook errors in qualitative and quantitative researches on microscopic pores of tight reservoirs caused by changes in the pore structure during sample preparation. Therefore, it is of great significance to establish a method capable of determining microscopic pore structure changes of nanoscale pores in a tight reservoir occurring in the structural damage process.
SUN1MARY Technical Problem [0005] The present disclosure provides a method for determining a change in a nanoscale pore structure and use thereof Solutions for the problems Technical solutions [0006] A method for determining a change in a nanoscale pore structure includes the following steps: [0007] a, putting a vacuum-degassed sample having a nanoscale pore structure into liquid nitrogen, detecting a nitrogen adsorption quantity of the sample under a plurality of preset pressure values P to obtain an isothermal adsorption curve showing changes of the nitrogen adsorption quantity of the sample with a relative pressure P/Po, where Po is a saturated vapor pressure of nitrogen at an adsorption temperature; [0008] b, selecting the isothermal adsorption curve within a range of 0.05,-13/130<0.35, obtaining a nitrogen volume Vo, needed by monolayer adsorption based on a slope s and an intercept i; calculating a specific surface area (SSA) of the sample by utilizing a Brunauer-Emmett-Teller (BET) specific surface area formula SSA=(Vmxa)/22400 W, where a is a sectional area of an adsorbed gas, and W is a mass of the vacuum-degassed sample; [0009] c, calculating volumes of micropores, mesopores and macropores by a non-local density functional theory (NLDFT) method, respectively, and then obtaining a sum and PV of the volumes of the micropores, the mesopores and the macropores in the sample and a change trend of PV with a pulverizing mesh number; and [0010] d, calculating the values of SSAJPV under different pulverized particle sizes of the sample, and determining the influence of a pulverizing process on the nanoscale pore structure according to an increasing change trend of the value of SSAJPV with a pulverizing mesh number. [0011] As an embodiment, a temperature for vacuum degassing in step a ranges from 90°C to 120°C.
100121 As an embodiment, the vacuum degassing in step a lasts for greater than or equal to 9 h. [0013] As an embodiment, step b may specifically include selecting an isothermal adsorption curve within a range of 0.05<P/P0<0.35 and obtaining the nitrogen volume Vm needed by monolayer adsorption based on the slope s and the intercept i. The selection of the isothermal adsorption curve within the above range can help further reduce the error of the determination method.
100141 As an embodiment, in step b, a relationship of the Vm to the slope s and the intercept i is: V111/(s+i). A relationship of Vm to the slope s of the isothermal adsorption curve within the range of 0.05<P/Po<0.35 is: s=(C-1)/(Vm/C), where C is a BET constant. A relationship of V111 to the intercept i of the isothermal adsorption curve within the range of 0.05<P/Po<0.35 is: i=1/(VmxC), where C is a BET constant. Thus, the following formula is derived: Vm=1/(s+i).
100151 As an embodiment, step c may specifically include selecting values within a range of 0.01<P/Po<0.995 and obtaining the volumes of the micropores, the mesopores and the macropores from statistics of ASiQ software by the NLDFT method.
[0016] As an embodiment, step d may specifically include determining the change in the nanoscale pore structure in the sample based on the changes of the value of SSA/PV when the pulverized particle size of the sample ranges from 20 mesh to 200 mesh.
100171 The present disclosure further provides use of the determination method in determining the influence of a sample preparation damage process on a nanoscale pore structure of a tight reservoir. The method for determining a change in a nanoscale pore structure provided in the present disclosure can qualitatively determine microscopic pore structure changes of nanoscale pores in a tight reservoir occurring in the structural damage (sample pulverizing) process based on the changes in SSAJPV of the sample under different pulverized particle sizes by characterizing the parameters such as the specific surface area, the pore volume and the pore size diameter of the microscopic pores of tight rock. Thus, errors of research results caused by changes in the pore structure during sample preparation in traditional methods of qualitative and quantitative researches on nanoscale pores of tight reservoirs can be avoided. If the value of SSA/PV changes significantly with changing pulverizing mesh number, it can be determined that the sample preparation damage process has different degrees of influences on the nanoscale pore structure of the tight reservoir.
[0018] The present disclosure further provides use of the determination method in determining the accuracy of pore structure test characterization data of a tight reservoir sample having a nanoscale pore structure. The magnitude of an error can be determined based on the magnitude of the change rate of SSA/PV, and then the error can be corrected. Thus, the accuracy of the traditional methods of qualitative and quantitative researches on nanoscale pores of tight reservoirs can be improved [0019] As an embodiment, when the pulverized particle size of the sample ranges from 20 mesh to 200 mesh, the value of SSA/PV decreases and a correlation coefficient 1(2 of the value of SSA/PV changing with the pulverizing mesh number is more than or equal to 0.6, indicating that the pore structure test characterization data of the tight reservoir sample having a nanoscale pore structure has a certain error and needs to be corrected. A correlation coefficient R2 may differ for the values of SSA/PV of different samples changing with a pulverizing mesh number, indicating that the value of SSA/PV is also related to the pore type of the sample. The occurrence and seepage of petroleum and natural gas mainly take place in the nanoscale pore and fracture system in a tight reservoir. When the pulverized particle size of the sample ranges from 20 mesh to 200 mesh, the value of SSA/PV decreases and a correlation coefficient R' of the value of SSA/PV changing with the pulverizing mesh number is more than or equal to 0.6, indicating that an error existing in traditional detection of the pore structure test characterization data of the tight reservoir would affect or even mislead the effective and reasonable evaluation and determination on the pore and fracture system in the tight reservoir, which may go against the effective exploration and exploitation of oil and gas resources
Beneficial Effects of the Present Disclosure
Beneficial effects [0020] As provided in the present disclosure, an isothermal adsorption curve showing changes of the nitrogen adsorption quantity with the relative pressure P/Po is established. The isothermal adsorption within the range of 0.05<P/Po<0.35 is selected, and the nitrogen volume Vm needed by monolayer adsorption is calculated. The specific surface area (SSA) of the sample is then calculated by the BET specific surface area formula. Thus, highly accurate SSA values of the sample under different pulverizing mesh numbers can be obtained. By the NLDFT method, critical P/Po values for micropores, mesopores and macropores are separately collected, so as to obtain the volumes of the micropores, the mesopores and the macropores. Thus, the changes of the volumes of different types of pores in the sample with increasing pulverized particle size are obtained. Finally, the change in the nanoscale pore structure is determined based on the changes of SSA/PV of the sample under different pulverized particle sizes.
[0021] The determination method provided in the present disclosure can accurately detect the SSA and total PV values of the sample under different pulverized particle sizes, and can not only determine the influence of the sample preparation damage process on the nanoscale pore structure in the tight reservoir sample but also accurately determine errors of research results caused by changes in the pore structure during sample preparation in traditional methods of qualitative and quantitative researches on nanoscale pores of tight reservoirs. In short, the determination method is of great significance for the exploration and exploitation of tight oil and gas resources.
BRIEF DESCRIPTION OF THE DRAWINGS
Description of drawings
[0022] FIG. 1 is a diagram illustrating an isothermal adsorption curve of sample 1 under different pulverizing mesh numbers in an embodiment of the present disclosure.
100231 FIG. 2 is a diagram illustrating an isothermal adsorption curve of sample 2 under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0024] FIG. 3 is a diagram illustrating an isothermal adsorption curve of sample 3 under different pulverizing mesh numbers in an embodiment of the present disclosure.
100251 FIG. 4 is a diagram illustrating an isothermal adsorption curve of sample 4 under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0026] FIG. 5 is a diagram illustrating an isothermal adsorption curve of sample 5 under different pulverizing mesh numbers in an embodiment of the present disclosure.
100271 FIG. 6 is a diagram illustrating an isothermal adsorption curve of sample 6 under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0028] FIG. 7 is a diagram illustrating a change curve of SSA values of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0029] FIG. 8 is a diagram illustrating an increase rate curve of SSA of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0030] FIG. 9 is a diagram illustrating a change curve of volumes of micropores of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0031] FIG. 10 is a diagram illustrating a change curve of volumes of mesopores of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0032] FIG. 11 is a diagram illustrating a change curve of volumes of macropores of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0033] FIG. 12 is a diagram illustrating a change curve of PV values of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
100341 FIG. 13 is a diagram illustrating an increase rate curve of PA values of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
[0035] FIG. 14 is a diagram illustrating a change curve of values of SSA/PV of 6 samples under different pulverizing mesh numbers in an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
100361 Embodiments [0037] 1. Device [0038] Low temperature nitrogen adsorption apparatus 100391 2. Samples 100401 Shale rock cores are obtained by well drilling, and 6 shale rock core samples are selected, each pulverized into 20 mesh, 80 mesh, and 200 mesh.
100411 3. Determination method 100421 The samples are vacuum-degassed at a temperature of 100°C for 9 h. The mass W of each vacuum-degassed sample is obtained by calculating a difference between the mass of a tube holding the sample after the degassing and the mass of the empty tube before the degassing. The degassed sample is put into liquid nitrogen, and the nitrogen adsorption quantities of the sample under a plurality of preset pressure points are detected to obtain the isothermal adsorption curve of the sample. The isothermal adsorption curves of 6 samples under different pulverizing mesh numbers are as shown in FIG. I to FIG. 6.
100431 The isothermal adsorption curve within a range of 0.1<iP/Po<0.3 is selected, and the nitrogen volume V111 needed by monolayer adsorption is obtained based on a slope s and an intercept i: Vin=1/(s+i). The specific surface area (SSA) of the sample is calculated by utilizing the BET specific surface area formula 55A=(V.xa)/22400 W, where a is the sectional area of the adsorbed gas, and W is the mass of the vacuum-degassed sample. The SSA values of 6 samples calculated under different pulverizing mesh numbers are as shown in Table 1, and the change curve of the SSA values of 6 samples under different pulverizing mesh numbers is as shown in FIG. 7.
100441 Table 1 SSA Values of 6 Samples Under Different Pulverizing Mesh Numbers
Table 1
Sample No. SSA Value (m2/8) SSA Value (m2/8) SSA Value (m2/8) Mesh 80 Mesh 200 Mesh 1 6.897 6.778 6.471 2 8.168 7.223 6.748 3 4.414 7.384 7.212 4 8.18 9.993 6.185 2.703 2.186 2.387 6 4.09 4.99 4.413 100451 Increments and increase rates of SSA of 6 samples with increasing pulverizing mesh number are calculated from the SSA values of the samples under different pulverizing mesh numbers in Table 1. The calculation results are as shown in Table 2, and the increase rate curve of SSA is as shown in FIG. 8.
100461 Table 2 Increments and Increase Rates of SSA
Table 2
Sample No. Increment of Increment of SSA Increase Rate of Increase Rate of SSA Under 20-80 Under 80-200 SSA Under SSA Under 80-200 Mesh Mesh 20-80 Mesh Mesh 1 -0.119 -0.307 -1.73% -4.53% 2 -0.945 -0.475 11.57 -6.58% 3 2.790 -0.172 67.29% -2.33% 4 1.813 -3.808 22.16% -38.11% -0.517 0.201 1 9 13% 9.19% 6 0.900 -0.577 22.00% -11.56% 100471 Values within the range of 0.01<P/P0<0.995 are selected, and the volumes of the micropores, the mesopores and the macropores in the sample are obtained from statistics of ASiQ software by the NLDFT method, whereby the total PV of the micropores, the mesopores and the macropores in the sample is obtained. In this manner, the volumes and the total PV values of the micropores, the mesopores and the macropores of 6 samples under different pulverizing mesh numbers are calculated. The calculated volume values of the micropores, the mesopores and the macropores are as shown in Table 3. The volume change curve of the micropores is as shown in FIG. 9, while the volume change curve of the mesopores is as shown in FIG. 10 and the volume change curve of the macropores is as shown in FIG. 11. The calculated total PV values are as shown in Table 4, and the change curve of the PV values is as shown in FIG. 12.
100481 Table 3 Volumes of Micropores, Mesopores and Macropores
Table 3
Sample Pulverizing Mesh Volume cc/g of Volume cc/g of Volume cc/g of No. Number Micropores Mesopores Macropores 1 20 0.00261 0.012181 0.003309 1 80 0.002831 0.013422 0.010147 1 200 0.002505 0.01237 0.006675 2 20 0.003489 0.011512 0.003069 2 80 0.002907 0.014975 0.012348 2 200 0.002646 0.016932 0.016272 3 20 0.001684 0.003281 0.002929 3 80 0.002899 0.011326 0.014595 3 200 0.002899 0.015749 0.013612 4 20 0.003625 0.0047156 0.0029594 4 80 0.003898 0.012406 0.022646 4 200 0.0025 0.019966 0.022064 20 0.0007351 0.0032649 0.000752 80 0.0007948 0.0052052 0.00671 200 0.0008545 0.0054411 0.0066644 6 20 0.001542 0.0054033 0.0017597 6 80 0.001916 0.010672 0.013082 6 200 0.001712 0.012501 0.017957 [0049] Table 4 Total PV values of 6 Samples Under Different Pulverizing Mesh Numbers Table 4 Sample No. PV Value (cc/g) PV Value (cc/g) PV Value (cc/g) Mesh 80 Mesh 200 Mesh 1 0.018100 0.026400 0.02155 2 0.018070 0.030230 0.03585 3 0.007894 0.028820 0.03226 4 0.011300 0.038950 0.04453 0.004752 0.012710 0.01296 6 0.008705 0.025670 0.03217 [0050] Increments and increase rates of PV of 6 samples with increasing pulverizing mesh number are calculated from the total PV values of the samples under different pulverizing mesh numbers in Table 3. The calculation results are as shown in Table 5, and the increase rate curve of PV of 6 samples with increasing pulverizing mesh number is plotted, as shown in FIG. 13. 10051] Table 5 Increments and Increase Rates of PV
[Table 5]
Sample increment of PV increment of PV increase Rate of PV increase Rate of PV No. Under 20-80 Mesh Under 80-200 Mesh Under 20-80 Mesh Under 80-200 Mesh 1 0.008300 -0.004850 45.86% -18.37% 2 0.012160 0.005620 67.29% 18.59% 3 0.020926 0.003440 265.09% -1-1.94% 4 0.027650 0.005580 244.69% 14.33% ) 0.007958 0.000250 167.47% 1.97% 6 0.016965 0.006500 194.89% 25.32% 100521 As can be seen from the data in Tables 1 and 2 and Tables 4 and 5 and FIG. 7, FIG. 8, FIG. 12 and FIG. 13, changes in SSA and PV in the pore and fracture system of the rock samples with the pulverizing mesh number of the samples increasing from 20 mesh to 80 mesh and then to 200 mesh are as follows: [0053] 1) SSA does not change a lot, and PV increases greatly. Under experimental conditions, the pulverizing process of the shale rock sample from 20 mesh to 80 mesh and then to 200 mesh causes only a small change in the micropores in the rock sample. The content of the micropores does not change a lot. During sample preparation, the quantity of the mesopores and the macropores in the sample increases with increasing pulverizing mesh number. The increase in the quantity of the macropores may be attributed to: a, the mesopores being damaged and the pores being communicated into the macropores; and b, new fractures being formed such that the previously closed pores are communicated with one another.
100541 2) In the pulverizing process from 80 mesh to 200 mesh, the increase rate of PV changes a little as compared with that in the process from 20 mesh to 80 mesh. The damage to the shale rock sample caused by the pulverizing process from 20 mesh to 80 mesh results in a significant increase in communicated pores in the pore and fracture system, causing the PV values to increase significantly. In the damage process from 80 mesh to 200 mesh to the shale rock sample, a few communicated pores are formed, and the micropores do not change a lot. In other words, in the pulverizing process from 20 mesh to 80 mesh, the pore structure of the shale rock sample is basically damaged, and no more new pores and fractures can be formed by continuous pulverization.
[0055] Therefore, with increasing pulverizing mesh number in the sample pulverizing preparation process, new communicated pores are formed in the shale rock sample, and these communicated pores are opened through added micro-fractures. However, such an increasing trend does not continue all through. When the pulverized particle size reaches a particular value, the increase amplitude of the pore volume of the sample is reduced. At this time, the microscopic pore structure of the shale rock sample is basically damaged, resulting in no more pores and fractures formed 100561 3) Statistical analysis is performed on SSA/PV data, and the results are as shown in Table 6 [0057] Table 6 SSA/PV Values and Change Rates of Samples from 20 Mesh to 80 Mesh and to 200 Mesh
Table 6
Sample No. SSA/PV Under 20 Mesh SSA/PV Under 80 Mesh SSA/PV Under 200 Mesh Increase Rate of SSA/PV Under 20-80 Mesh Increase Rate of SSA/PV Under 80-200 Mesh 6 381.0497 256.7424 300.2784 -32.6223% 16.9571% 13 452.0199 238.9348 188.2287 -47.1406% -21.2217% 5591589 256.2110 223.5586 -54.1792% -12.7443% 44 723.8938 256.5597 138.8951 -64.5584% -45.8625% 46 568.8131 171.9906 184.1821 -69.7633% 7.0885% 52 469.8449 194.3903 137.1775 -58.6267% -29.4319% [0058] Change curves of SSA/PV of 6 samples between 80 mesh and 200 mesh are plotted based on the data in Table 6. The change curves of SSA/PV are as shown in FIG. 14.
[0059] From Table 6 and FIG. 14, in the process of increasing the pulverizing mesh number of the sample from 20 mesh to 80 mesh and then to 200 mesh, the value of SSA/PV has a certain correlation to the pulverizing mesh number (with l't2 changing within a range of 0.6-0.8), and SSA/PV has a decreasing trend with the pulverizing mesh number. This indicates that the increase of the pulverizing mesh number leads to an increase in communicated pores in the pore system during sample preparation, resulting in formation of new pores and fractures. As a result, the pore volume increases, and damage is caused to the nanoscale pore structure of the shale rock core. The comparison of change rates of SSA/PV values of different types of samples may show that the degree of sample preparation damage causes great errors of traditional pore structure test characterization data, which may affect the results of oil and gas exploration. Thus, the related characterization data needs to be corrected.
[0060] The above detection results further verify the feasibility of using the changes of SSA/PV with the mesh number to determine the change in the microscopic pore structure of the tight reservoir during sample preparation and to determine the accuracy of the accuracy of the pore structure test characterization data of the tight reservoir sample having the nanosca1e pore structure.
[0061] The foregoing are merely descriptions of the preferred embodiment of the present disclosure, and are not intended to limit the present disclosure. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present disclosure shall fall within the protection scope of the present disclosure.
Claims (10)
- WHAT IS CLAIMED IS: I. A method for determining a change in a nanoscale pore structure, comprising the following steps: a, putting a vacuum-degassed sample having a nanoscale pore structure into liquid nitrogen, detecting a nitrogen adsorption quantity of the sample under a plurality of preset pressure values P to obtain an isothermal adsorption curve showing changes of the nitrogen adsorption quantity of the sample with a relative pressure P/Po, the Po being a saturated vapor pressure of nitrogen at an adsorption temperature; b, selecting the isothermal adsorption curve within a range of 0.05<P/Po<0.35, obtaining a nitrogen volume V. needed by monolayer adsorption based on a slope s and an intercept i; calculating a specific surface area (SSA) of the sample by utilizing a Brunauer-Emmett-Teller (BET) specific surface area formula SSA=(V./a)/22400 W, wherein a is a sectional area of an adsorbed gas, and W is a mass of the vacuum-degassed sample; c, calculating volumes of micropores, mesopores and macropores by a non-local density functional theory (NLDFT) method, respectively, and then obtaining a sum PV of the volumes of the micropores, the mesopores and the macropores in the sample; and d, calculating the values of SSA/PV under different pulverized particle sizes of the sample, and determining the influence of a pulverizing process on the nanoscale pore structure according to an increasing change trend of the value of SSAJPV with a pulverizing mesh number.
- 2. The method according to claim I, wherein a temperature for vacuum degassing in step a ranges from 90°C to 120°C
- 3. The method according to claim 1, wherein the vacuum degassing in step a lasts for greater than or equal to 9 h.
- 4. The method according to claim 1, wherein step b specifically comprises selecting an isothermal adsorption curve within a range of 0.1<P/Po<0.3 and obtaining the nitrogen volume V. needed by monolayer adsorption based on the slope s and the intercept i.
- 5. The method according to claim I, wherein in step b, a relationship of the V. to the slope s and the intercept i is: V.=1/(s+i).
- 6. The method according to claim 1, wherein step c specifically comprises selecting values within a range of 0.01<P/P0<0.995 and obtaining the volumes of the micropores, the mesopores and the macropores from statistics of ASiQ software by the NLDFT method.
- 7. The method according to claim 1, wherein step d specifically comprises determining the change in the nanoscale pore structure in the sample based on the changes of the value of SSA/PV when the pulverized particle size of the sample ranges from 20 mesh to 200 mesh.
- 8. Use of the method for determining a change in a nanoscale pore structure according to any one of claims 1 to 7 in determining the influence of a sample preparation damage process on a nanoscale pore structure of a tight reservoir.
- 9. Use of the method for determining a change in a nanoscale pore structure according to any one of claims t to 7 in determining the accuracy of pore structure test characterization data of a tight reservoir sample having a nanoscale pore structure.
- 10. The use according to claim 9, wherein when the pulverized particle size of the sample ranges from 20 mesh to 200 mesh, the value of SSA/PV decreases and a correlation coefficient IV of the value of SSA/PV changing with the pulverizing mesh number is more than or equal to 0.6, indicating that the pore structure test characterization data of the tight reservoir sample having a nanoscale pore structure has an error and needs to be corrected.
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| CN113192119B (en) * | 2021-05-27 | 2023-01-06 | 宜宾学院 | Quantitative statistical method for porosity of multi-scale pore surface |
| CN114608991A (en) * | 2022-05-09 | 2022-06-10 | 宁德厦钨新能源材料有限公司 | Method for detecting specific surface area of ternary material and lithium cobaltate material |
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002042744A1 (en) * | 2000-11-21 | 2002-05-30 | Akzo Nobel N.V. | Method of analysing microporous material |
| CN103339488A (en) * | 2011-01-27 | 2013-10-02 | 普拉德研究及开发股份有限公司 | Gas sorption analysis of unconventional rock samples |
| CN103674802A (en) * | 2013-11-05 | 2014-03-26 | 中国石油天然气股份有限公司 | Rock closed porosity determination method |
| CN105043957A (en) * | 2015-07-06 | 2015-11-11 | 成都理工大学 | Method for determining pore structure through classifying isothermal adsorption curve of mud shale |
| CN105445161A (en) * | 2015-11-16 | 2016-03-30 | 中国石油大学(北京) | Characterizing method for pore volumes of full apertures of shale |
| CN106442268A (en) * | 2016-10-31 | 2017-02-22 | 中国科学技术大学 | Method for detecting pore size distribution of shale mesopores |
| CN107421864A (en) * | 2016-05-23 | 2017-12-01 | 中国石油化工股份有限公司 | The assay method of the total specific surface area of micro- mesoporous solid material and micropore specific area |
| CN109839401A (en) * | 2019-01-29 | 2019-06-04 | 太原理工大学 | A kind of judgement and processing method of goaf seam area |
| CN111537416A (en) * | 2020-04-10 | 2020-08-14 | 中国地质大学（北京） | Method for judging change of nanoscale pore structure and application |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3059011B1 (en) * | 2015-02-19 | 2018-05-02 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Carbon porous body, method for producing the same, and ammonia-adsorbing material |
| CN104634718B (en) * | 2015-03-05 | 2017-03-22 | 中国石油大学(华东) | Calibration method for representing dense sandstone pore size distribution by adopting nuclear magnetic resonance |
| CN105424580B (en) * | 2016-01-14 | 2018-10-02 | 太原理工大学 | A kind of coal full aperture measures and its hole shape semidefinite quantization method |
| JP6960622B2 (en) * | 2016-09-05 | 2021-11-05 | 旭化成株式会社 | Porous carbon material and its manufacturing method, composite and its manufacturing method, and positive electrode material for lithium-sulfur batteries |
| CN106525691A (en) * | 2016-12-09 | 2017-03-22 | 河南理工大学 | Method for determining full-pore-diameter pore structure of coal through multi-data fusion |
-
2020
- 2020-04-10 CN CN202010281035.2A patent/CN111537416B/en active Active
- 2020-08-26 GB GB2213108.0A patent/GB2607836A/en active Pending
- 2020-08-26 WO PCT/CN2020/111476 patent/WO2021203611A1/en active Application Filing
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002042744A1 (en) * | 2000-11-21 | 2002-05-30 | Akzo Nobel N.V. | Method of analysing microporous material |
| CN103339488A (en) * | 2011-01-27 | 2013-10-02 | 普拉德研究及开发股份有限公司 | Gas sorption analysis of unconventional rock samples |
| CN103674802A (en) * | 2013-11-05 | 2014-03-26 | 中国石油天然气股份有限公司 | Rock closed porosity determination method |
| CN105043957A (en) * | 2015-07-06 | 2015-11-11 | 成都理工大学 | Method for determining pore structure through classifying isothermal adsorption curve of mud shale |
| CN105445161A (en) * | 2015-11-16 | 2016-03-30 | 中国石油大学(北京) | Characterizing method for pore volumes of full apertures of shale |
| CN107421864A (en) * | 2016-05-23 | 2017-12-01 | 中国石油化工股份有限公司 | The assay method of the total specific surface area of micro- mesoporous solid material and micropore specific area |
| CN106442268A (en) * | 2016-10-31 | 2017-02-22 | 中国科学技术大学 | Method for detecting pore size distribution of shale mesopores |
| CN109839401A (en) * | 2019-01-29 | 2019-06-04 | 太原理工大学 | A kind of judgement and processing method of goaf seam area |
| CN111537416A (en) * | 2020-04-10 | 2020-08-14 | 中国地质大学（北京） | Method for judging change of nanoscale pore structure and application |
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| CN111537416B (en) | 2021-10-22 |
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