Method for characterizing rock water vapor adsorption behavior

Abstract

The invention discloses a characterization method of rock water vapor adsorption behavior, and relates to the field of unconventional oil gas characterization, the method comprises the following steps: providing a dried rock powder sample; performing a water vapor adsorption experiment on the rock powder sample to obtain adsorption data of the rock powder sample, the adsorption data comprising water vapor adsorption amounts under different relative humidity; fitting the adsorption data in the logarithmic form to obtain a target curve, determining the target relative humidity according to the relative humidity corresponding to the maximum change point of the slope of the target curve, the target relative humidity being the relative humidity at the beginning of the capillary condensation action of the rock powder sample; according to the Dent adsorption model and the target relative humidity, the single-layer adsorption capacity, the multi-layer adsorption capacity and the capillary condensation adsorption capacity of the rock powder sample under different relative humidity are determined. According to the method, the single-layer adsorption capacity, the multi-layer adsorption capacity and the capillary condensation adsorption capacity of the rock powder sample under different relative humidity can be obtained respectively.

Description

Technical Field

[0001] This application relates to the field of unconventional oil and gas characterization, and in particular to a method for characterizing the adsorption behavior of water vapor in rocks. Background Technology

[0002] Water adsorption behavior in unconventional reservoirs is of great significance for the evaluation, exploration, and development of oil and gas resources. Furthermore, in the field of CO2 geological storage, the water adsorption behavior of rocks also has a significant impact on CO2 storage efficiency and safety. However, current research on water adsorption behavior in unconventional reservoirs mainly focuses on the total adsorption amount, which is limited, and research on further subdividing the adsorption process is lacking.

[0003] Traditional water vapor adsorption experiments can only measure the change in total adsorption with relative humidity, failing to reflect the contribution of various adsorption processes within the total adsorption. Because different adsorption processes have different mechanisms, their significance for the water adsorption capacity of rock samples also varies. Furthermore, current rock water vapor adsorption experiments cannot precisely measure the adsorption amounts produced by different adsorption processes. Summary of the Invention

[0004] The purpose of this application is to provide a method for characterizing the water vapor adsorption behavior of rocks, and to determine the monolayer adsorption capacity, multilayer adsorption capacity, and capillary condensation adsorption capacity of rock powder samples under different relative humidities. This method can solve the problem that current rock water vapor adsorption experiments cannot accurately measure the adsorption capacity generated by different adsorption processes.

[0005] To achieve the above objectives, this application provides the following solution: This application provides a method for characterizing the water vapor adsorption behavior of rocks, comprising: Provide samples of dried rock powder; A water vapor adsorption experiment was conducted on the rock powder sample to obtain adsorption data of the rock powder sample, including the amount of water vapor adsorbed under different relative humidities. The target curve is obtained by fitting the adsorption data in logarithmic form. The target relative humidity is determined by the relative humidity corresponding to the point where the slope of the target curve changes the most. The target relative humidity is the relative humidity at the beginning of capillary coagulation of the rock powder sample. Based on the Dent adsorption model and the target relative humidity, the monolayer adsorption capacity, multilayer adsorption capacity, and capillary condensation adsorption capacity of the rock powder sample under different relative humidities were determined.

[0006] This application provides a method for characterizing the water vapor adsorption behavior of rocks: First, a water vapor adsorption experiment is conducted on the rock powder sample to obtain the water vapor adsorption amount of the rock powder sample under different relative humidities; then, these adsorption data are converted into logarithmic form and fitted, and the slope of the fitted curve characterizes the adsorption intensity. Since the adsorption intensity of the rock powder sample varies significantly under different adsorption stages (the first stage is monolayer adsorption and multilayer adsorption, and the second stage is capillary condensation), the point where the slope of the target curve changes the most is the critical point at which capillary condensation begins, and the relative humidity corresponding to this point is the relative humidity at the beginning of capillary condensation, i.e., the target relative humidity; finally, by combining the target relative humidity with the Dent adsorption model, the saturation value of the multilayer adsorption of the rock powder sample can be calculated. Based on this saturation value, the multilayer adsorption amount and capillary condensation amount in the Dent adsorption model calculation results can be further subdivided, and finally, the monolayer adsorption amount, multilayer adsorption amount, and capillary condensation adsorption amount of the rock powder sample under different relative humidities can be obtained respectively. Therefore, the characterization method for rock water vapor adsorption behavior provided in the above embodiments solves the problem that current rock water vapor adsorption experiments cannot accurately measure the amount of adsorption produced by different adsorption processes. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a flowchart illustrating a method for characterizing the water vapor adsorption behavior of rocks according to an embodiment of this application; Figure 2 for Figure 1 A detailed flowchart of step 120; Figure 3 This is a graph showing the fitting result of the Freundlich isotherm model with respect to logarithmic adsorption data in one embodiment of this application; Figure 4 for Figure 1 A detailed flowchart of step 140; Figure 5 This is a graph showing the fitting result of the Dent adsorption model with respect to adsorption data in one embodiment of this application.

[0009] Figure label: Detailed Implementation

[0010] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0011] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0012] In one exemplary embodiment, such as Figure 1 As shown, a method for characterizing the water vapor adsorption behavior of rocks is provided, comprising the following steps 110 to 140. Wherein: Step 110: Provide a sample of the dried rock powder.

[0013] To accurately measure the water vapor adsorption behavior of rocks, it is necessary to avoid interference from the initial moisture in the rocks, therefore the rock powder samples need to be dried.

[0014] First, a rock powder sample needs to be prepared. For example, a certain mass of sample can be taken from the target rock and crushed into rock powder of 60-80 mesh to obtain the rock powder sample.

[0015] The rock powder sample is then dried. For example, the rock powder sample can be placed in a drying oven and dried at 60°C for 48 hours.

[0016] Step 120: Conduct a water vapor adsorption experiment on the rock powder sample to obtain adsorption data of the rock powder sample, including the amount of water vapor adsorbed under different relative humidities.

[0017] Among them, reference Figure 2 The water vapor adsorption experiment on the rock powder sample specifically includes steps 121 and 122.

[0018] Step 121: In a test environment at the target temperature, iteratively record the equilibrium mass of the rock powder sample at the current relative humidity; wherein, the current relative humidity is iteratively increased according to a preset step size, and the equilibrium mass is the mass when the mass change is less than a preset threshold and maintained for a preset time.

[0019] For example, the target temperature can be set between 20℃ and 60℃, and the relative humidity can be iteratively increased within the range of 0-0.95 according to a preset step size. The preset step size can be 0.1, the preset threshold can be a change of 0.002% per minute, and the preset time can be 10 minutes. It should be noted that, depending on the test range and test accuracy of the experiment, the above parameters can also be set to other values.

[0020] Step 122: Determine the water vapor adsorption capacity of the rock powder sample at each relative humidity based on the equilibrium mass of the rock powder sample at each relative humidity.

[0021] For any relative humidity, the mass of water vapor adsorbed by the rock powder sample at that humidity can be obtained by subtracting the initial mass of the rock powder sample from its equilibrium mass at that humidity. In this embodiment, the ratio between the mass of adsorbed water vapor and the initial mass of the rock powder sample is used to characterize the amount of water vapor adsorbed.

[0022] For example, the water vapor adsorption capacity of a rock powder sample at any relative humidity S. A S The objective formula is determined as follows: in, M S and M O These represent the equilibrium mass of the rock powder sample under relative humidity S and in its initial state, respectively. It should be noted that in this embodiment, the unit of water vapor adsorption is mg / g, which represents the number of mg of water vapor absorbed per g of rock powder. In other embodiments, the unit of water vapor adsorption can be defined as other values, such as g / g, in which case the constant 1000 in the target formula can be omitted.

[0023] Based on the above examples of steps 121 and 122, the following is an example of a water vapor adsorption experiment: 1. Start the water vapor adsorption apparatus, keep the sample chamber open, and purge the sample chamber with dry nitrogen for 10 minutes to dry it. After calibrating the microbalance of the equipment, set the mass to [value missing]. M 0 A sample of rock powder (approximately 20 mg) was loaded into the sample chamber and the sample chamber was closed.

[0024] 2. Set the test environment temperature (20-60℃) according to experimental requirements. Set the relative humidity for each test level at 0.1 intervals, gradually increasing the relative humidity from 0 to 0.95. Set the equilibration time to ensure that the mass change of the rock powder sample is less than 0.002% per minute and maintain this for 10 minutes before moving to the next relative humidity level.

[0025] 3. After setting up, start the test. The instrument will automatically increase the relative humidity from 0 to 1 and record the mass of the rock powder sample at the end of each level, thus obtaining each relative humidity and its corresponding rock powder sample mass.

[0026] 4. Calculate the amount of water adsorbed by the rock powder sample at each relative humidity using the target formula.

[0027] Step 130: Fit the adsorption data in logarithmic form to obtain the target curve, and determine the target relative humidity by the relative humidity corresponding to the point where the slope of the target curve changes the most. The target relative humidity is the relative humidity at the beginning of capillary coagulation of the rock powder sample.

[0028] In this step, a coordinate system is established with the logarithm of relative humidity as the abscissa and the logarithm of water vapor adsorption as the ordinate. Different data points in the coordinate system represent adsorption data in logarithmic form. These data points are then fitted to obtain a target curve, the slope of which characterizes the water vapor adsorption intensity of the rock powder sample. The adsorption intensity of the rock powder sample varies significantly under different adsorption conditions. Specifically, in the monolayer and multilayer adsorption stages, the rock powder sample can maintain approximately one adsorption intensity, while in the capillary condensation stage, it maintains a different adsorption intensity. This difference is reflected in the target curve, which is essentially formed by two (approximate) straight line segments with different slopes. The point where these two segments connect is the point of maximum slope change in the target curve, representing the transition from the capillary condensation stage to the capillary condensation stage—the critical point at the onset of capillary condensation. The relative humidity corresponding to this critical point is the relative humidity at the beginning of capillary condensation in the rock powder sample.

[0029] The Freundlich isotherm model can be used to fit the data. For example, fitting the logarithmic adsorption data to obtain the target curve specifically includes: establishing a coordinate system with the logarithm of relative humidity as the abscissa and the logarithm of water vapor adsorption as the ordinate, and mapping the logarithmic adsorption data into the coordinate system; linearly fitting the coordinate system using the linear form of the Freundlich isotherm model to obtain the target curve, which consists of two straight line segments with different slopes, and the junction of the two segments is the point of maximum slope change of the target curve.

[0030] The linear expression for the Freundlich isotherm model is: in, A Indicates the amount of water vapor adsorbed. k and n All of these represent constant coefficients. n Characterizes adsorption strength ，S This indicates relative humidity. n A larger value indicates a stronger interaction between the pore surface and water molecules, resulting in a stronger adsorption strength. For the linear fitting results of the Freundlich isotherm model, 1 / n This represents the slope of the fitted line; therefore, a larger slope indicates... n The smaller the value, the weaker the adsorption strength.

[0031] It should be noted that the two straight line segments in the target curve have different linear expressions. These two linear expressions have different constant coefficients.

[0032] Specifically, refer to Figure 3 Based on the different slopes of the linearly fitted lines, the data points in the coordinate system can be divided into two regions: low relative humidity and high relative humidity. Two linear formulas are obtained by fitting the Freundlich isotherm model to each region. The line with a smaller slope corresponds to a larger slope in the low relative humidity region. n The value (indicating stronger adsorption strength) represents the monolayer and multilayer adsorption of water molecules on the pore surface. A steeper slope in the high relative humidity region corresponds to a smaller value. n The value (meaning a weaker adsorption strength) represents capillary coagulation.

[0033] Step 140: Determine the monolayer adsorption capacity, multilayer adsorption capacity, and capillary condensation adsorption capacity of the rock powder sample under different relative humidities based on the Dent adsorption model (Dent multicomponent adsorption model) and the target relative humidity.

[0034] The Dent adsorption model can characterize two different types of adsorption in rock powder samples, quantifying the relationship between water vapor adsorption and relative humidity under different effects. First, it can characterize monolayer adsorption, directly calculating the monolayer adsorption amount at any relative humidity. Second, it can characterize the combined effects of multilayer adsorption and capillary condensation, but it cannot further subdivide multilayer adsorption and capillary condensation; that is, it can directly calculate the sum of multilayer adsorption and capillary condensation at any relative humidity, but cannot differentiate between the two. Considering that capillary condensation occurs when multilayer adsorption becomes saturated, the target relative humidity calculated in the previous steps can be substituted into the Dent adsorption model to calculate the multilayer adsorption saturation value. If the relative humidity to be calculated is less than the target relative humidity, the calculated adsorption amount is entirely multilayer adsorption. If the relative humidity to be calculated is greater than the target relative humidity, the calculated adsorption amount is the sum of multilayer adsorption and capillary condensation; subtracting the multilayer adsorption saturation value from this sum yields the corresponding capillary condensation amount. Therefore, in this embodiment, by combining the Dent adsorption model with the target relative humidity, the monolayer adsorption capacity, multilayer adsorption capacity, and capillary condensation adsorption capacity at any relative humidity can be calculated.

[0035] Reference Figure 4 In this embodiment, step 140 includes steps 141 and 142.

[0036] Step 141: The amount of water vapor adsorbed under different relative humidities is fitted by the Dent adsorption model to obtain the first model and the second model of the rock powder sample. The first model is used to characterize the monolayer adsorption, and the second model is used to characterize the combined effect of multilayer adsorption and capillary condensation.

[0037] The first model is: in, A 1. P M and Q 1 represents the monolayer adsorption capacity, maximum monolayer adsorption value, and intensity of monolayer adsorption of the rock powder sample, respectively. S Indicates relative humidity. Q 2 represents the total intensity of multilayer adsorption and capillary coagulation.

[0038] The second model is: in, A 2 represents the sum of multilayer adsorption and capillary agglomeration in the rock powder sample. P M , Q 1 andQ 2 represents the maximum monolayer adsorption value, the intensity of monolayer adsorption, and the total intensity of multilayer adsorption and capillary coagulation for the rock powder sample, respectively. S This indicates relative humidity.

[0039] Reference Figure 5 Specifically, a coordinate system was established with relative humidity as the x-axis and water vapor adsorption as the y-axis. Water vapor adsorption at different relative humidities was mapped onto the coordinate system. The Dent adsorption model was then used to fit the data points in the coordinate system. The fitting results are as follows: in, A This indicates the total adsorption amount of the rock powder sample. A = A 1+ A 2.

[0040] Based on the above fitting results, the Dent adsorption model can classify adsorption into two categories, resulting in the first model and the second model. The first model is a model of the change of monolayer adsorption capacity with relative humidity, while the second model is a model of the change of the sum of multilayer adsorption capacity and capillary condensation capacity with relative humidity.

[0041] Step 142 involves determining the monolayer adsorption capacity of the rock powder sample under different relative humidities based on the first model, and determining the multilayer adsorption capacity and capillary condensation adsorption capacity of the rock powder sample under different relative humidities based on the second model and the target relative humidity. This step specifically includes: 1. Substitute the target relative humidity into the second model to obtain the maximum value of the multilayer adsorption capacity of the rock powder sample.

[0042] 2. For any first relative humidity, substitute the first relative humidity into the second model to obtain the multilayer adsorption amount of the rock powder sample under the first relative humidity. The first relative humidity is less than the target relative humidity.

[0043] 3. For any second relative humidity, after substituting the second relative humidity into the second model, subtract the maximum value of the multilayer adsorption from the calculation result of the second model to obtain the capillary condensation adsorption amount of the rock powder sample under the second relative humidity. The second relative humidity is greater than the target relative humidity.

[0044] After determining the first and second models, substituting any relative humidity into the first model allows direct calculation of the monolayer adsorption capacity of the rock powder sample at that relative humidity. For any relative humidity less than the target relative humidity, substituting it into the second model allows direct calculation of the multilayer adsorption capacity of the rock powder sample at that relative humidity, in which case the capillary condensation capacity is 0. For any relative humidity greater than the target relative humidity, substituting it into the second model allows calculation of the sum of the multilayer adsorption capacity and the capillary condensation capacity of the rock powder sample at that relative humidity. Since the multilayer adsorption capacity is already saturated at the target relative humidity, subtracting the multilayer adsorption capacity saturation value from the calculation result yields the capillary condensation capacity of the rock powder sample at that relative humidity, in which case the multilayer adsorption capacity is its own saturation value.

[0045] The above describes a method for characterizing the water vapor adsorption behavior of rocks provided in this embodiment. In one example: assuming the water vapor adsorption amount of a rock powder sample at a relative humidity of 0.9 needs to be determined, the target relative humidity calculated in step 130 is 0.7827. Substituting 0.7827 into the fitted second model yields a multilayer adsorption saturation value of 13.25 mg / g for the rock powder sample. Substituting 0.9 into the first model yields a single-layer adsorption amount of 4.87 mg / g. Substituting 0.9 into the second model yields a sum of multilayer adsorption and capillary condensation amounts of 26.78 mg / g. Subtracting 13.25 mg / g from 26.78 mg / g yields a capillary condensation amount of 13.53 mg / g for the rock powder sample. Therefore, referring to… Figure 4 At a relative humidity of 0.9, the monolayer adsorption capacity of the rock powder sample was 4.87 mg / g, the multilayer adsorption capacity was 13.25 mg / g, and the capillary condensation capacity was 13.53 mg / g, with a total adsorption capacity of 31.65 mg / g. The monolayer adsorption capacity, multilayer adsorption capacity, and capillary condensation capacity accounted for 15.39%, 41.86%, and 42.75% of the total adsorption capacity, respectively.

[0046] Furthermore, for multiple rock powder samples tested under the same conditions, the Dent model can also be used to... Q 1. Comparison of parameters: The relative adsorption strength of water molecules on the surfaces of different rock powder samples. The strength of multilayer adsorption gradually decreases with the increase of the number of adsorption layers. Capillary condensation, on the other hand, mainly depends on the interaction between water molecules, and the adsorption strength is basically consistent.

[0047] In summary, the method for characterizing the water vapor adsorption behavior of rocks provided in this embodiment is as follows: First, water vapor adsorption experiments are conducted on rock powder samples to obtain the water vapor adsorption amount of the rock powder samples under different relative humidities. Then, these adsorption data are converted into logarithmic form and fitted. The slope of the fitted curve characterizes the adsorption intensity. Since the adsorption intensity of the rock powder samples varies significantly in different adsorption stages (the first stage is monolayer adsorption and multilayer adsorption, and the second stage is capillary condensation), the point where the slope of the target curve changes the most is the critical point at which capillary condensation begins. The relative humidity corresponding to this point is the relative humidity at the beginning of capillary condensation, i.e., the target relative humidity. Finally, by combining the target relative humidity with the Dent adsorption model, the saturation value of the multilayer adsorption of the rock powder samples can be calculated. Based on this saturation value, the multilayer adsorption and capillary condensation amounts in the Dent adsorption model calculation results can be further subdivided. Finally, the monolayer adsorption, multilayer adsorption, and capillary condensation adsorption amounts of the rock powder samples under different relative humidities can be obtained respectively. Therefore, the characterization method for rock water vapor adsorption behavior provided in the above embodiments solves the problem that current rock water vapor adsorption experiments cannot accurately measure the amount of adsorption produced by different adsorption processes.

[0048] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0049] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for characterizing the water vapor adsorption behavior of rocks, characterized in that, include: Provide samples of dried rock powder; A water vapor adsorption experiment was conducted on the rock powder sample to obtain adsorption data of the rock powder sample, including the amount of water vapor adsorbed under different relative humidities. The target curve is obtained by fitting the adsorption data in logarithmic form. The target relative humidity is determined by the relative humidity corresponding to the point where the slope of the target curve changes the most. The target relative humidity is the relative humidity at the beginning of capillary coagulation of the rock powder sample. Based on the Dent adsorption model and the target relative humidity, the monolayer adsorption capacity, multilayer adsorption capacity, and capillary condensation adsorption capacity of the rock powder sample under different relative humidities were determined.

2. The method for characterizing the water vapor adsorption behavior of rocks according to claim 1, characterized in that, The water vapor adsorption experiment on the rock powder sample includes: In a test environment at the target temperature, the equilibrium mass of the rock powder sample at the current relative humidity is iteratively recorded; wherein, the current relative humidity is iteratively increased according to a preset step size, and the equilibrium mass is the mass when the mass change is less than a preset threshold and maintained for a preset time; The water vapor adsorption capacity of the rock powder sample at each relative humidity is determined based on the equilibrium mass of the rock powder sample at each relative humidity.

3. The method for characterizing the water vapor adsorption behavior of rocks according to claim 2, characterized in that, Water vapor adsorption capacity of the rock powder sample at any relative humidity S A S The target formula is determined by the objective formula, which is: in, M S and M O These represent the equilibrium mass of the rock powder sample under relative humidity S and in its initial state, respectively.

4. The method for characterizing the water vapor adsorption behavior of rocks according to claim 2, characterized in that, The target temperature is set between 20°C and 60°C.

5. The method for characterizing the water vapor adsorption behavior of rocks according to claim 2, characterized in that, The relative humidity is iteratively increased within the range of 0-0.95 according to a preset step size, where the preset step size is 0.1, the preset threshold is a change of 0.002% per minute, and the preset time is 10 minutes.

6. The method for characterizing the water vapor adsorption behavior of rocks according to claim 1, characterized in that, The process of fitting the logarithmic adsorption data to obtain the target curve includes: A coordinate system is established with the logarithm of the relative humidity as the abscissa and the logarithm of the water vapor adsorption amount as the ordinate, and the adsorption data in logarithmic form is mapped to the coordinate system. The target curve is obtained by linearly fitting the coordinate system using the linear form of the Freundlich isotherm model. The target curve consists of two straight line segments with different slopes, and the junction of the two straight line segments is the point where the slope of the target curve changes the most.

7. The method for characterizing the water vapor adsorption behavior of rocks according to claim 1, characterized in that, The determination of the monolayer adsorption capacity, multilayer adsorption capacity, and capillary condensation adsorption capacity of the rock powder sample under different relative humidities based on the Dent adsorption model and the target relative humidity includes: The first model and the second model of the rock powder sample were obtained by fitting the water vapor adsorption amount under different relative humidities using the Dent adsorption model. The first model is used to characterize monolayer adsorption, and the second model is used to characterize the combined effect of multilayer adsorption and capillary condensation. The monolayer adsorption capacity of the rock powder sample under different relative humidities is determined according to the first model, and the multilayer adsorption capacity and capillary condensation adsorption capacity of the rock powder sample under different relative humidities are determined according to the second model and the target relative humidity.

8. The method for characterizing the water vapor adsorption behavior of rocks according to claim 7, characterized in that, The determination of the multilayer adsorption and capillary condensation adsorption of the rock powder sample under different relative humidities based on the second model and the target relative humidity includes: Substituting the target relative humidity into the second model yields the maximum value of the multilayer adsorption capacity of the rock powder sample; For any first relative humidity, the first relative humidity is substituted into the second model to obtain the multilayer adsorption amount of the rock powder sample at the first relative humidity, where the first relative humidity is less than the target relative humidity; For any second relative humidity, the capillary condensation adsorption amount of the rock powder sample at the second relative humidity is obtained by subtracting the maximum value of the multilayer adsorption amount from the calculation result of the second model after substituting the second relative humidity into the second model. The second relative humidity is greater than the target relative humidity.

9. The method for characterizing the water vapor adsorption behavior of rocks according to claim 7, characterized in that, The first model is: in, A 1. P M and Q 1 represents the monolayer adsorption capacity, maximum monolayer adsorption value, and intensity of monolayer adsorption of the rock powder sample, respectively. S Indicates relative humidity. Q 2 represents the total intensity of multilayer adsorption and capillary coagulation.

10. The method for characterizing the water vapor adsorption behavior of rocks according to claim 7, characterized in that, The second model is: in, A 2 represents the sum of multilayer adsorption and capillary agglomeration in the rock powder sample. P M , Q 1 and Q 2 represents the maximum monolayer adsorption value, the intensity of monolayer adsorption, and the total intensity of multilayer adsorption and capillary coagulation of the rock powder sample, respectively. S This indicates relative humidity.

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