A method for quantitatively measuring organic pores and inorganic pores in shale

Abstract

The present invention provides a quantitative measurement method for organic pores and inorganic pores in shale, comprising the following steps: S1, obtaining a shale sample, and measuring the mass m and apparent volume V of the shale sample after drying. total , calculate the apparent volume V per unit mass of shale sample bulk :S2, calculate the ratio C of the organic matter area to the organic origin pore area of the shale sample; S3, obtain the pore volume V1 per unit mass of the shale sample; S4, select part of the shale sample to prepare it into powder, and measure the mass m of the powdered shale sample powder The powdered shale sample was burned and the skeleton volume V of the powdered shale sample after burning was measured. skeleton ; S5, calculate the skeleton volume V2 of the unit mass of shale sample: S6, calculate the organic matter volume V of the unit mass of shale sample OM , organic pore content V OM pore , Inorganic pore content V inorganicpore The beneficial effect of the present invention is that the organic pore and inorganic pore contents of shale are quantitatively calculated based on the difference between inorganic mineral components and organic components of shale during combustion.

Description

Technical Field

[0001] The present invention relates to the technical field of shale reservoir evaluation, exploration and development, and particularly relates to a method for quantitatively measuring organic pores and inorganic pores in shale. Background Art

[0002] In the exploration and development of shale gas, it is found that the pore characteristics of shale are closely related to the gas-bearing characteristics of the reservoir. The pores in shale originate from inorganic minerals and organic matter. The contents of organic pores and inorganic pores in shale are closely related to the wettability, adsorption, connectivity, etc. of the reservoir. Their quantitative characterization is conducive to better evaluating the reservoir storage performance subsequently.

[0003] At present, most pore characterization methods obtain the total pores of shale and cannot directly distinguish the contents of inorganic pores and organic pores. Existing methods for quantitatively calculating the contents of inorganic pores and organic pores include X-ray based CT scan three-dimensional reconstruction method, field emission scanning electron microscope image quantitative statistics method, and nuclear magnetic resonance method based on the wettability of organic pores and inorganic pores. The above methods are limited by their own pore size characterization ranges and cannot accurately calculate the contents of inorganic pores and organic pores in the full pore size range of shale. Moreover, the quantitative statistics method based on field emission scanning electron microscope images has a large requirement for the number of statistical samples. For the nuclear magnetic resonance method using the wetting phase as the calculation standard for organic pores and inorganic pores, due to many influencing factors of the wetting phase and the inability of nuclear magnetic resonance to measure closed pores, there are large errors in its results. Summary of the Invention

[0004] In view of this, in order to solve the problem that the contents of organic pores and inorganic pores in shale cannot be accurately measured currently, an embodiment of the present invention provides a method for quantitatively measuring organic pores and inorganic pores in shale.

[0005] An embodiment of the present invention provides a method for quantitatively measuring organic pores and inorganic pores in shale, including the following steps:

[0006] S1. Obtain a regular solid shale sample, dry the shale sample, measure the mass m and apparent volume V of the dried shale sample, and calculate the apparent volume V in the shale sample per unit mass: total and calculate the apparent volume V in the shale sample per unit mass bulk :

[0007]

[0008] S2. Through an image processing software, statistically analyze the organic matter area and organically formed pore area in the argon ion polished scanning electron microscope image of the shale sample, and calculate the ratio C of the organic matter area to the organically formed pore area in the shale sample;

[0009] S3. Perform pore size testing on the shale sample to obtain the pore volume V1 in the shale sample per unit mass;

[0010] S4. Select a part of the shale sample to prepare it into powder, and measure the mass m of the powdered shale sample. powder , Conduct a combustion treatment on the powdered shale sample to completely burn the organic matter in the powdered shale sample, and measure the skeletal volume V of the powdered shale sample after combustion. skeleton ;

[0011] S5. Calculate the skeletal volume V2 of the shale sample per unit mass:

[0012]

[0013] S6. According to the volume relationship V of the shale sample per unit mass bulk = V1 + V2 + V OM Calculate the organic matter volume V OM , organic pore content V OM pore , inorganic pore content V inorganicpore :

[0014] V OM = V bulk - V1 - V2;

[0015]

[0016] V inorganic pore = V1 - V OM pore .

[0017] Further, the specific method for drying the shale sample in step S1 is: drying and vacuumizing the shale sample in an oven, continuously weighing the shale sample during this period until the mass of the shale sample does not change, and completing the drying.

[0018] Further, step S2 is specifically: continuously counting the organic matter area and the organically - originated pore area in the argon ion polished scanning electron microscope image of the shale sample through image - processing software, and simultaneously calculating the ratio of the organic matter area to the organically - originated pore area until the ratio is stable to obtain the ratio C of the true organic matter area to the organically - originated pore area of the shale sample.

[0019] Further, the method for pore size testing of the shale sample in step S3 is one or more of pore characterization means such as gas adsorption, small - angle scattering, helium porosity, and nuclear magnetic resonance.

[0020] Further, the method for pore size testing of the shale sample in step S3 is: using a CO2 adsorption experiment to characterize the pore volume of the shale with a pore size below 1 nm, an N2 adsorption experiment to characterize the pore volume of the shale with a pore size of 1 - 50 nm, and a high - pressure mercury injection experiment to characterize the pore volume of the shale with a pore size > 50 nm.

[0021] Further, in step S4, the particle size of the powdered shale sample is <200 mesh.

[0022] Further, in step S4, when burning the powdered shale sample, the skeletal volume of the powdered shale sample after burning is measured midway until the skeletal volume no longer changes to complete the burning.

[0023] Further, in step S4, the powdered shale sample is burned in a muffle furnace, and the skeletal volume V of the powdered shale sample after burning skeleton is measured by the helium method using an Anton Paar Ultrapyc-5000 fully automatic true density analyzer.

[0024] Further, the mass m of the shale sample in step S1 and the mass m of the powdered shale sample in S4 powder are both measured by an analytical balance.

[0025] Further, the apparent volume V of the shale sample in step S1 total is measured by a vernier caliper.

[0026] The beneficial effects brought by the technical solution provided by the embodiments of the present invention are as follows: A quantitative measurement method for organic pores and inorganic pores in shale of the present invention, based on the differences between inorganic mineral components and organic components in shale during combustion, quantitatively calculates the contents of organic pores and inorganic pores in shale, solves the problem that most pore characterization means cannot directly distinguish the contents of inorganic pores and organic pores, and the accurate test methods for the contents of some inorganic pores and organic pores in shale are limited by their own pore size characterization ranges, resulting in insufficient accuracy. It can well quantitatively evaluate the number of inorganic pores and organic pores in shale, understand the contribution degrees of inorganic pores and organic pores in shale, has wider applicability and stronger practicability than previous methods, and has industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of a quantitative measurement method for organic pores and inorganic pores in shale of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the drawings. The following describes a relatively optimal one among multiple possible embodiments of the present invention, aiming to provide a basic understanding of the present invention, but not aiming to identify the key or decisive elements of the present invention or limit the scope to be protected.

[0029] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0030] Please refer to Figure 1 , an embodiment of the present invention provides a method for quantitatively measuring organic pores and inorganic pores in shale, comprising the following steps:

[0031] S1. Obtain a regular solid shale sample, the shape of the shale sample is regular and convenient for measuring its apparent volume. For example, a shale sample with a cuboid shape can be selected.

[0032] Dry the shale sample: Place the shale sample in an oven at 120°C for drying and vacuum treatment. During this period, continuously weigh the shale sample until the mass of the shale sample does not change, and the drying is completed. At this time, it is considered that the adsorbed gas and moisture in the shale sample have been excluded.

[0033] Measure the mass m and apparent volume V of the dried shale sample total , the mass m of the shale sample is measured by a high-precision analytical balance, and the apparent volume V total is measured by a high-precision vernier caliper.

[0034] According to the mass m and apparent volume V of the shale sample total Calculate the apparent volume V in the shale sample per unit mass bulk :

[0035]

[0036] S2. Through an image processing software, statistically analyze the organic matter area and organically formed pore area in the argon ion polished scanning electron microscope image of the shale sample, and calculate the ratio C of the organic matter area to the organically formed pore area in the shale sample. Here, through the graphic processing software ImageJ, continuously statistically analyze the organic matter area and organically formed pore area in the argon ion polished scanning electron microscope image of the shale sample, and at the same time calculate the ratio of the organic matter area to the organically formed pore area, until the ratio is stable, and the true ratio C of the organic matter area to the organically formed pore area in the shale sample is obtained.

[0037] S3. Conduct pore size testing on the shale sample to obtain the pore volume V1 in the shale sample per unit mass. For the shale sample, various testing methods can be used, such as gas adsorption, small angle scattering, helium porosity, and nuclear magnetic resonance. In actual testing, one or a combination of them can be selected according to the dominant pore size characterization range of different testing methods to test and obtain the sum of the pore volumes of all pore sizes in the shale sample, and then calculate the ratio of the sum of the pore volumes of all pore sizes to the mass m of the shale sample, so as to determine the pore volume V1 in the shale sample per unit mass.

[0038] In this embodiment, the method for pore size testing of shale samples is as follows: the CO2 adsorption experiment is used to characterize the pore volume of shale with pore sizes below 1 nm, the N2 adsorption experiment is used to characterize the pore volume of shale with pore sizes between 1 and 50 nm, and the high-pressure mercury intrusion experiment is used to characterize the pore volume of shale with pore sizes > 50 nm.

[0039] S4. Select a part of the shale sample to make it into powder. The particle size of the powdered shale sample is < 200 mesh, so that the organic matter in the subsequent powdered shale sample is easier to burn fully. Measure the mass m of the powdered shale sample powder , the mass m of the powdered shale sample before combustion powder is measured by a high-precision analytical balance.

[0040] Then, perform a combustion treatment on the powdered shale sample to completely burn the organic matter in the powdered shale sample. For example, place the powdered shale sample in a muffle furnace and burn it at 350 °C. When burning the powdered shale sample, measure the skeleton volume of the powdered shale sample after combustion midway until the skeleton volume no longer changes, indicating that the organic matter in the powdered shale sample has been completely burned, and the combustion is completed.

[0041] Measure the skeleton volume V of the powdered shale sample after combustion skeleton , where the skeleton volume V of the powdered shale sample after combustion skeleton is measured by using the helium method with an Anton Paar Ultrapyc-5000 fully automatic true density analyzer.

[0042] S5. Calculate the skeleton volume V2 of the shale sample per unit mass:

[0043]

[0044] S6. According to the volume relationship formula V bulk = V1 + V2 + V OM of the shale sample per unit mass, calculate the organic matter volume V OM , organic pore content V OM pore , inorganic pore content V inorganicpore :

[0045] V OM = V bulk - V1 - V2;

[0046]

[0047] V inorganic pore = V1 - V OM pore .

[0048] The quantitative measurement method for organic and inorganic pores in shale overcomes the problem that most pore characterization methods cannot directly distinguish the content of inorganic pores and organic pores, and can accurately calculate the content of organic pores and inorganic pores in the whole pore size range of shale. It has stronger applicability and practicability than previous methods and has guiding significance for shale oil and gas exploration and reservoir evaluation.

[0049] In this article, the front, back, up, down and other orientation words are defined based on the positions of the components in the drawings and the positions of the components relative to each other, only for the sake of clarity and convenience in expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different usage and placement methods. The use of the orientation words should not limit the scope of protection claimed in this application.

[0050] Without conflict, the above-mentioned embodiments and the features in the embodiments in this article can be combined with each other.

[0051] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for quantitatively measuring organic pores and inorganic pores in shale, characterized in that, It includes the following steps: S1. Obtain a regular solid shale sample, dry the shale sample, and measure the mass m and apparent volume V of the dried shale sample, and calculate the apparent volume V in the shale sample per unit mass. total , and calculate the apparent volume V in the shale sample per unit mass. bulk : S2. Use image processing software to count the organic matter area and the organogenic pore area in the argon ion polished scanning electron microscope image of the shale sample, and calculate the ratio C of the organic matter area to the organogenic pore area of the shale sample; S3. Conduct pore size tests on the shale sample to obtain the pore volume V1 in the shale sample per unit mass; S4. Select a part of the shale sample to prepare it into powder, and measure the mass m of the powdered shale sample powder , conduct a combustion treatment on the powdered shale sample to completely burn the organic matter in the powdered shale sample, and measure the skeletal volume V of the powdered shale sample after combustion skeleton ; S5. Calculate the skeleton volume V2 of the shale sample per unit mass: S6. Calculate the organic matter volume V, organic pore content V, and inorganic pore content V of the shale sample per unit mass according to the volume relationship V of the shale sample per unit mass: bulk = V1 + V2 + V OM OM , organic pore content V OMpore , and inorganic pore content V inorganicpore :​ VOM = Vbulk - V1 - V2; Vinorganic pore = V1 - V OMpore 。 2. The quantitative measurement method for organic pores and inorganic pores in shale according to claim 1, characterized in that, The specific method for drying the shale sample in step S1 is: dry the shale sample in an oven under vacuum treatment, continuously weigh the shale sample during this period until the mass of the shale sample does not change, and complete the drying.

3. The quantitative measurement method of organic pores and inorganic pores in shale according to claim 1, wherein Step S2 is specifically: continuously use graphic processing software to count the organic matter area and the organogenic pore area in the argon ion polished scanning electron microscope image of the shale sample, and simultaneously calculate the ratio of the organic matter area to the organogenic pore area until the ratio is stable to obtain the true ratio C of the organic matter area to the organogenic pore area of the shale sample.

4. The quantitative measurement method of organic pores and inorganic pores in shale according to claim 1, characterized in that The method for conducting pore size tests on the shale sample in step S3 is one or more of the pore characterization means.

5. A method for quantitatively measuring organic pores and inorganic pores in shale as described in claim 1, characterized in that, The method for conducting pore size tests on the shale sample in step S3 is: use the CO2 adsorption experiment to characterize the pore volume of the shale with a pore size below 1 nm, use the N2 adsorption experiment to characterize the pore volume of the shale with a pore size of 1 - 50 nm, and use the high-pressure mercury intrusion experiment to characterize the pore volume of the shale with a pore size > 50 nm.

6. The quantitative measurement method for organic pores and inorganic pores in shale according to claim 1, characterized in that The particle size of the powdered shale sample in step S4 is < 200 mesh.

7. The quantitative measurement method for organic pores and inorganic pores in shale according to claim 1, wherein, In step S4, when burning the powdered shale sample, measure the skeleton volume of the powdered shale sample after combustion midway until the skeleton volume no longer changes to complete the combustion.

8. A method for quantitatively measuring organic pores and inorganic pores in shale according to claim 1, characterized in that, In the step S4, the powdered shale sample is burned in a muffle furnace, and the skeletal volume V of the burned powdered shale sample skeleton is measured by using the helium method with an Anton Paar Ultrapyc-5000 fully automatic true density analyzer.

9. The quantitative measurement method for organic pores and inorganic pores in shale according to claim 1, characterized in that The mass m of the shale sample in step S1 and the mass m of the powdered shale sample in S4 powder are both measured by an analytical balance.

10. A method for quantitatively measuring organic pores and inorganic pores in shale according to claim 1, characterized in that, The apparent volume V of the shale sample in the step S1 total is measured by a vernier caliper.

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