A method for preparing layered salt rock similar materials containing insoluble interlayers

Abstract

This invention discloses a method for preparing a layered salt rock similar material containing insoluble interlayers, relating to the field of salt rock technology. The key technical points are: S1: Layering; based on the positional relationship of the pure salt rock layer, hard interlayers, and weak interlayers of the layered salt rock in different simulated regions, the layers of the layered salt rock similar material are sequentially pressed in a mold to obtain the layered salt rock similar material; S2: The layered salt rock similar material obtained in step S1 is removed from the mold and then placed in a drying oven at 60-80℃ for 36 hours, followed by standing at room temperature for 7 days to obtain the final layered salt rock similar material. The method of this invention can produce salt rock similar materials containing both hard and weak interlayers, more accurately simulating the mechanical properties of layered salt rock and the influence of interlayer variation characteristics on the mechanical properties of the surrounding rock. Furthermore, the raw materials are readily available and the preparation is convenient.

Description

Technical Field

[0001] This invention relates to the field of salt rock technology, and more specifically, to a method for producing a layered salt rock similar material containing insoluble interlayers. Background Technology

[0002] Salt rock, with its extremely low permeability, good rheological properties, and excellent self-healing characteristics, is internationally recognized as an ideal gas storage facility. Deep-seated gas storage facilities not only offer advantages such as high storage pressure and large storage capacity but also effectively isolate the impact of fires and earthquakes. However, with increasing depth, the pressure within the formation also increases, causing changes in the mechanical properties of the surrounding rock under long-term stress. Therefore, research on the mechanical properties of salt rock is crucial. Currently, most salt rock studies rely on in-situ core sampling. While the experimental results are closer to the actual conditions of salt rock, in-situ sampling is often difficult. Furthermore, for layered salt rocks containing interlayers such as mudstone, gypsum, and glaucophane, the interlayer characteristics in layered salt rock samples exhibit significant dispersion, making it difficult to determine the influence of interlayer characteristics on the mechanical properties of layered salt rock.

[0003] Using similar model materials to create salt rock samples to replace prototypes for testing and research avoids the difficulty of on-site sampling and reduces research costs. In recent years, some scholars have studied similar materials for salt rock, but most studies have not fully considered the interlayering of salt rock, making it difficult to obtain the influence of interlayer variations on the mechanical properties of salt rock. This results in significant errors between the research results and actual mechanical properties, making them unrealistic. In studies of salt rock similar materials that consider interlayering, gypsum is often used to simulate gypsum rock, and gypsum is also the main binder. However, the hardness of gypsum material decreases significantly after absorbing moisture, causing the prepared salt rock similar materials to become unusable after a period of time due to moisture absorption. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a layered salt rock similar material containing insoluble interlayers, so as to solve the above-mentioned technical problems.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for producing a layered salt rock similar material containing insoluble interlayers, comprising the following steps:

[0006] S1: Pressing; Based on the positional relationship of pure salt rock layers, hard interlayers and weak interlayers of interlayered salt rock in different simulated regions, the layers of interlayered salt rock similar material are pressed sequentially in the mold to obtain interlayered salt rock similar material.

[0007] S2: Take the layered salt rock similar material obtained in step S1 out of the mold, then put it into a drying oven at a temperature of 60-80℃ for 36 hours, and then let it stand at room temperature for 7 days to obtain the final layered salt rock similar material.

[0008] The present invention is further configured such that: in step S1, the method for preparing the pure salt rock layer includes: adding water to industrial salt and stirring it evenly, then placing it into a mold, wherein the particle diameter of the industrial salt is 1-2 mm, the water content of the industrial salt is controlled to be 8%-10%, applying pressure to the industrial salt in the mold, maintaining the pressure at 100-150 MPa, and the pressure duration is 60-150 min, thereby obtaining the pure salt rock layer.

[0009] The present invention is further configured such that: in step S1, the preparation method of the rigid sandwich layer includes: adding water to refined iron powder, salt powder, gypsum, sodium sulfate decahydrate and polyvinyl alcohol and stirring into a uniform paste, then placing it into a mold for pressing, maintaining the pressure at 80-120 MPa, and the pressure duration at 60-120 min, thereby obtaining the rigid sandwich layer; the ratio of gypsum to sodium sulfate decahydrate is between 1:1.9 and 1:2.1.

[0010] The present invention is further configured such that: in step S1, the method for preparing the soft interlayer includes: mixing bentonite, salt powder and epoxy resin with water to form a uniform paste, then placing it in a mold for pressing, maintaining the pressure at 80-120 MPa for a duration of 60-120 min, and obtaining the soft interlayer after pressing.

[0011] The present invention is further configured such that, when preparing the rigid sandwich layer, the content of refined iron powder and polyvinyl alcohol is adjusted according to the strength of the simulated rigid sandwich layer.

[0012] The present invention is further configured such that: when preparing the rigid interlayer, the content of gypsum is consistent with the content of calcium sulfate in the simulated rigid interlayer, the content of sodium sulfate decahydrate is consistent with the content of sodium sulfate in the simulated rigid interlayer, and the content of salt powder is consistent with the content of sodium chloride in the simulated rigid interlayer.

[0013] The present invention is further configured such that: when preparing the weak interlayer, the content of salt powder is consistent with the content of sodium chloride in the simulated weak interlayer; and the content of bentonite is adjusted according to the strength of the simulated hard interlayer.

[0014] The present invention is further configured such that: in step S1, before pressing, a layer of lubricating oil is brushed inside the mold.

[0015] In summary, the present invention has the following beneficial effects:

[0016] 1. It can produce salt rock similar materials containing hard and weak interlayers, which can more accurately simulate the mechanical properties of interlayered salt rock and the influence of interlayer variation characteristics on the mechanical properties of surrounding rock. Moreover, the raw materials are readily available and the manufacturing process is convenient.

[0017] 2. In the preparation of the rigid interlayer, sodium sulfate decahydrate is added. The combination of sodium sulfate decahydrate and gypsum allows for a more realistic reproduction of the calcium sulfate interlayer within the rigid interlayer. Sodium sulfate decahydrate has a certain degree of hygroscopicity, which can adjust the moisture content of gypsum in the interlayer-like salt rock material, preventing the gypsum from becoming damp, better maintaining the mechanical properties of the gypsum, and extending the shelf life of the interlayer-like salt rock material. Furthermore, during the preparation of the rigid interlayer, the gypsum releases heat when mixed with water, while sodium sulfate decahydrate absorbs heat when dissolved in water. This allows the mixture to cool to room temperature more quickly during the preparation of the rigid interlayer.

[0018] 3. Polyvinyl alcohol is used as an auxiliary binder in the preparation of rigid sandwich layers, and the strength of rigid sandwich layers can be adjusted.

[0019] 4. Using pure industrial salt as aggregate can fully reflect the good creep and self-healing properties of salt rock. It takes into account both hard and soft interlayers in salt rock, which facilitates targeted research on interlayers. Furthermore, the number, thickness, and location of interlayers can be changed according to the characteristics of salt rock in different regions. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the fabrication process of a layered salt rock-like material according to an embodiment of the present invention.

[0021] Figure 2 It is a layered salt rock-like material prepared according to the manufacturing method described in this invention. Detailed Implementation

[0022] The following is in conjunction with the appendix Figure 1-2 The present invention will be described in further detail below.

[0023] Example: A method for preparing a layered salt rock-like material containing insoluble interlayers, such as... Figure 1-2 As shown, the method includes the following steps:

[0024] S1: Pressing; Based on the positional relationship of pure salt rock layers, hard interlayers and weak interlayers of interlayered salt rock in different simulated regions, the layers of interlayered salt rock similar material are pressed sequentially in the mold to obtain interlayered salt rock similar material; before pressing, a layer of lubricating oil is brushed inside the mold.

[0025] S2: Take the layered salt rock similar material obtained in step S1 out of the mold, then put it into a drying oven at a temperature of 60-80℃ for 36 hours, and then let it stand at room temperature for 7 days to obtain the final layered salt rock similar material.

[0026] The preparation method of pure salt rock layer includes: adding water to industrial salt and stirring evenly, then placing the mixture into a mold. The particle diameter of the industrial salt is 1-2 mm, and the water content of the industrial salt is controlled at 8%-10%. Pressure is applied to the industrial salt in the mold, maintaining a pressure of 100-150 MPa for a duration of 60-150 min, to obtain pure salt rock layer.

[0027] The preparation method of the rigid sandwich layer includes: mixing refined iron powder, salt powder, gypsum, sodium sulfate decahydrate, and polyvinyl alcohol with water to form a uniform paste, then pressing it in a mold, maintaining a pressure of 80-120 MPa for 60-120 minutes to obtain the rigid sandwich layer; the ratio of gypsum to sodium sulfate decahydrate is between 1:1.9 and 1:2.1. The content of refined iron powder and polyvinyl alcohol is adjusted according to the strength of the simulated rigid sandwich layer. The content of gypsum is consistent with the content of calcium sulfate in the simulated rigid sandwich layer, the content of sodium sulfate decahydrate is consistent with the content of sodium sulfate in the simulated rigid sandwich layer, and the content of salt powder is consistent with the content of sodium chloride in the simulated rigid sandwich layer. Gypsum is the main binder, and polyvinyl alcohol is the auxiliary binder; polyvinyl alcohol can adjust the strength of the material.

[0028] The ratio of gypsum to sodium sulfate decahydrate is between 1:1.9 and 1:2.1. In the salt rock interlayer, the proportions of sodium sulfate and calcium sulfate, the main components of sodium sulfate, are almost equal. Gypsum is susceptible to moisture, and the amount of sodium sulfate decahydrate can be appropriately increased according to the actual production and testing environment to achieve a better dehumidification effect and ensure that the mechanical properties of the interlayer do not change significantly.

[0029] The preparation method of the weak interlayer includes: mixing bentonite, salt powder, and epoxy resin with water to form a uniform paste, then placing the paste into a mold and pressing it under pressure of 80-120 MPa for 60-120 minutes. The resulting soft interlayer is then formed. The salt powder content is consistent with the sodium chloride content in the simulated weak interlayer; the bentonite content is adjusted according to the strength of the simulated hard interlayer.

[0030] This embodiment enables the preparation of salt rock similar materials containing hard and weak interlayers, which can more accurately simulate the mechanical properties of interlayered salt rock and the influence of interlayer variation characteristics on the mechanical properties of the surrounding rock. Moreover, the raw materials are readily available and the preparation is convenient.

[0031] In the preparation of the rigid interlayer, sodium sulfate decahydrate is added. The combination of sodium sulfate decahydrate and gypsum allows for a more realistic reproduction of the calcium sulfate interlayer within the rigid interlayer. Sodium sulfate decahydrate has a certain degree of hygroscopicity, which can adjust the moisture content of gypsum in the interlayer-like salt rock material, preventing the gypsum from becoming damp, better maintaining the mechanical properties of the gypsum, and extending the shelf life of the interlayer-like salt rock material. Furthermore, during the preparation of the rigid interlayer, the exothermic reaction of gypsum with water and the endothermic reaction of sodium sulfate decahydrate with water accelerate the cooling of the mixture to room temperature during the preparation of the rigid interlayer.

[0032] Polyvinyl alcohol is used as an auxiliary binder in the preparation of rigid sandwich layers, and its strength can be adjusted.

[0033] Using pure industrial salt as aggregate can fully reflect the good creep and self-healing properties of salt rock. It takes into account both hard and soft interlayers in salt rock, which facilitates targeted research on interlayers. Furthermore, the number, thickness, and location of interlayers can be changed according to the characteristics of salt rock in different regions.

[0034] Example 1: Pure salt rock samples were drilled from a salt cavern gas storage facility in Jintan, Jiangsu Province, as the target samples. The pure salt rock samples were pressed in the laboratory: industrial salt with a particle size of 1 mm was placed in a constant temperature chamber at 80℃ and dried for 48 hours. After drying, the salt was removed and placed in a mold for pressing, maintaining a pressure of 120 MPa for 100 minutes. After pressing, the salt was demolded and dried in a drying oven at 60-80℃ for 36 hours. The pressed samples were then left to stand at room temperature for seven days. Uniaxial compression tests were used to obtain the mechanical parameters of the target sample and the pressed samples. The parameter comparison is shown in Table 1.

[0035] Table 1. Comparison of mechanical parameters of the target specimen and the compressed specimen in Example 1.

[0036] type <![CDATA[Unit weight / KN / m 3 > Peak stress / MPa Elastic modulus / MPa Poisson's ratio Target sample 22.8 18.35 3.64 0.22 Pressed sample 21.34 20.67 3.47 0.19

[0037] Example 2: Salt rock samples containing hard interlayers were drilled from a salt cavern gas storage facility in Jintan, Jiangsu Province. The composition of salt and hard interlayers in the samples was analyzed. Then, in the laboratory, a molded salt sample containing hard interlayers was pressed. 175.6 g of refined iron powder, 133.2 g of salt powder, 108.6 g of gypsum, 217.2 g of sodium sulfate decahydrate, and 15 g of polyvinyl alcohol were mixed with water to form a paste to create the hard interlayer. The molded salt sample containing insoluble interlayers was then pressed according to the thickness and location of the interlayer in the target sample, maintaining a pressure of 120 MPa for 100 minutes. After pressing, the sample was demolded and dried in a drying oven at 60-80℃ for 36 hours. It was then left to stand at room temperature for seven days to obtain the pressed sample. Uniaxial compression tests were used to obtain the mechanical parameters of the target sample and the pressed sample. The parameter comparison is shown in Table 2.

[0038] Table 2 Comparison of Mechanical Parameters of Target Specimen and Pressed Specimen in Example 2

[0039] type <![CDATA[Unit weight / KN / m 3 > Peak stress / MPa Elastic modulus / MPa Poisson's ratio Target sample 25.26 36.8 4.95 0.24 Pressed sample 26.54 33.06 5.07 0.22

[0040] Example 3: Salt rock samples containing weak interlayers were drilled from a salt cavern gas storage facility in Jintan, Jiangsu Province. The composition of salt and weak interlayers in the samples was analyzed, and the mass ratio of pure salt to calcareous mudstone particles was calculated to be 5.2:1. Then, in the laboratory, the salt sample containing weak interlayers was pressed. 35.8g of bentonite, 186.3g of salt, and 13.2g of epoxy resin were mixed with water to form a uniform paste. The salt sample containing the interlayers was then pressed according to the thickness and location of the target sample interlayers, maintaining a pressure of 120MPa for 100min. After pressing, the sample was demolded and dried in a drying oven at 60-80℃ for 36h. It was then left to stand at room temperature for seven days to obtain the pressed sample. Uniaxial compression tests were used to obtain the mechanical parameters of the target sample and the pressed sample. The parameter comparison is shown in Table 3.

[0041] Table 3. Comparison of mechanical parameters of the target specimen and the compressed specimen in Example 3.

[0042] type <![CDATA[Unit weight / KN / m 3 > Peak stress / MPa Elastic modulus / MPa Poisson's ratio Target sample 21.65 5.3 0.62 0.25 Pressed sample 19.95 4.95 0.58 0.27

[0043] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing a layered salt rock-like material containing insoluble interlayers, characterized in that, The method includes the following steps: S1: Pressing; Based on the positional relationship of pure salt rock layers, hard interlayers and weak interlayers of interlayered salt rock in different simulated regions, the layers of interlayered salt rock similar material are pressed sequentially in the mold to obtain interlayered salt rock similar material. S2: Take the layered salt rock similar material obtained in step S1 out of the mold, then put it into a drying oven at a temperature of 60-80℃ for 36 hours, and then let it stand at room temperature for 7 days to obtain the final layered salt rock similar material. In step S1, the preparation method of the rigid sandwich layer includes: mixing refined iron powder, salt powder, gypsum, sodium sulfate decahydrate and polyvinyl alcohol with water to form a uniform paste, then placing it in a mold for pressing, maintaining the pressure at 80-120 MPa for 60-120 min, thereby obtaining the rigid sandwich layer; the ratio of gypsum to sodium sulfate decahydrate is between 1:1.9 and 1:2.

1.

2. The method for producing a layered salt rock similar material containing insoluble interlayers according to claim 1, characterized in that: In step S1, the method for preparing the pure salt rock layer includes: adding water to industrial salt and stirring it evenly, then placing it into a mold. The particle diameter of the industrial salt is 1-2 mm, and the water content of the industrial salt is controlled at 8%-10%. Pressure is applied to the industrial salt in the mold, maintaining the pressure at 100-150 MPa for a duration of 60-150 min, to obtain the pure salt rock layer.

3. The method for producing a layered salt rock similar material containing insoluble interlayers according to claim 1, characterized in that: In step S1, the method for preparing the soft interlayer includes: mixing bentonite, salt powder and epoxy resin with water to form a uniform paste, then placing it in a mold for pressing, maintaining the pressure at 80-120 MPa for 60-120 min, and obtaining the soft interlayer after pressing.

4. The method for producing a layered salt rock similar material containing insoluble interlayers according to claim 1, characterized in that: When preparing a rigid sandwich, the content of refined iron powder and polyvinyl alcohol is adjusted according to the strength of the rigid sandwich being simulated.

5. The method for producing a layered salt rock similar material containing insoluble interlayers according to claim 1, characterized in that: in When preparing the rigid interlayer, the gypsum content is consistent with the calcium sulfate content in the simulated rigid interlayer, the sodium sulfate decahydrate content is consistent with the sodium sulfate content in the simulated rigid interlayer, and the salt powder content is consistent with the sodium chloride content in the simulated rigid interlayer.

6. The method for preparing a layered salt rock similar material containing insoluble interlayers according to claim 3, characterized in that: When preparing the weak interlayer, the salt powder content is consistent with the sodium chloride content in the simulated weak interlayer; the bentonite content is adjusted according to the strength of the simulated weak interlayer.

7. The method for producing a layered salt rock similar material containing insoluble interlayers according to claim 1, characterized in that: In step S1, before pressing, a layer of lubricating oil is brushed inside the mold.

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