Thin interbedded salt tectonics experimental model and simulation method

Abstract

The present application relates to the technical field of salt structure compression and torsion experiment, in particular to a thin interbedded compression and torsion salt structure experiment model and a simulation method, comprising: a fixed seat, a first inclined surface is arranged at the first end of the fixed seat; a movable seat is arranged at the first end of the fixed seat and has a second inclined surface which is fitted with the inclined surface; a fixed plate is arranged along the X-axis direction and is connected to the upper end surface of the fixed seat; and a push plate is arranged along the X-axis direction and is connected to the upper end surface of the movable seat. The present application is based on the actual sample block of the target salt structure, analyzes the rheological properties of the gypsiferous salt layer under the in-situ temperature and pressure conditions underground, and then selects appropriate materials to simulate the formation of the experiment model; the formed salt structure structure layer is subjected to shear and extrusion deformation through the pushing action of the movable seat and the push plate, so that the experimenter obtains the deformation characteristics of the salt structure structure layer in the deformation process, which is beneficial for the experimenter to obtain the coupling-decoupling relationship of the layered differential deformation of the salt structure according to the experimental results.

Description

Technical Field

[0001] This invention relates to the field of salt structure compression-torsion experimental technology, and more specifically to experimental models and simulation methods for thin interlayered compression-torsion salt structures. Background Technology

[0002] In the field of salt structures, salt rocks refer to mixtures mainly composed of halite, including other evaporites (gypsum, anhydrite, etc.) and non-evaporites (mudstone, carbonate rocks, etc.). They possess a dense porous structure and high salinity, exhibiting plastic flow deformation under in-situ high temperature and pressure conditions underground. Salt structures refer to various landforms formed by salt layers during crustal movement. Their formation, evolution, and deformation mechanisms are a key focus of structural geology research and are of great significance for the exploration of underground resources and energy reserves.

[0003] Compressional-torsional structures are a special type of salt structure, characterized by the deformation of salt layers under compressional and torsional loads, forming complex folds and fractures. In compressional-torsional salt structures, due to differences in the physical properties of the salt layers and the stress conditions they experience, different layers exhibit different behaviors during deformation. Different layers of salt layers, under compressional and torsional loads, exhibit different deformation modes and degrees, such as folding, fracturing, or sliding. These differences lead to the complexity and diversity of salt structure morphology. Furthermore, different layers of salt layers exhibit different zonation and segmentation on the plane, including the formation of continuous structural zones, fractures or fault blocks, or anticlines, synclines, or fault patterns. These differences are determined by the physical properties of the salt layers themselves, the differences in stress conditions, and nonlinear characteristics. These differential deformation behaviors not only affect the morphology and distribution of salt structures but also have a significant impact on the distribution of related oil and gas reservoirs and mineral resources. For example, gypsum-salt layers, with their dense porous structure, are the highest quality and most effective caprock for oil and gas systems in basins. Due to their density and stability, gypsum-salt layers effectively prevent oil and gas escape, thereby improving oil and gas recovery rates and exploration success rates. Furthermore, gypsum-salt layers can provide ideal underground locations for deep CO2 geological sequestration and national energy allocation and storage. By utilizing the porous structure and sealing properties of gypsum-salt layers, efficient CO2 and energy storage can be achieved, contributing to mitigating climate change and meeting national energy needs.

[0004] Gypsum-salt layers are formed by the interlayering of thin layers of halite, gypsum, and mudstone, and can be termed thin-layered interbedded salt structures. Gypsum-salt layers in strata are viscoelastic fluids, readily undergoing plastic flow, which can lead to varying degrees of decoupling between the structures above and below the salt. This results in stratified differences in vertical structural deformation and segmented and zonal planar structural patterns within the region. The lateral differences in the composition, thickness, and rheological properties of gypsum-salt layers at different depths, temperatures, and pressures within the same structural zone are key factors controlling the lateral variations in salt structural deformation patterns. Compressional-shear faults, due to their combination of horizontal and dip displacements, coupled with the three-dimensional spatial complexity of related fault systems, have always been a challenge in structural geology. Quantitative research on the coupling and decoupling relationships of stratified deformation differences in compressional-shear salt structures is a cutting-edge key scientific issue in structural geology and the structural analysis of hydrocarbon basins.

[0005] Investigating the coupling and decoupling relationships of differential deformation in the layered structure of compressional-torsional salt structures requires experimental observation and a multidisciplinary approach, combining experimental observation, numerical simulation, and theoretical analysis. Establishing an experimental model of compressional-torsional salt structures that accurately reflects the spatial changes of each structural layer under compressional-torsional fracture deformation is a pressing issue. Summary of the Invention

[0006] To address the technical problems existing in the experimental model of compressive-torsional salt structures in the prior art, the first aspect of the present invention proposes an experimental model for thin interlayered compressive-torsional salt structures, comprising:

[0007] The fixing base has a first inclined surface at its first end;

[0008] A movable seat is disposed at the first end of the fixed seat and has a second inclined surface that fits against the inclined surface;

[0009] A fixing plate is arranged along the X-axis and connected to the upper end face of the fixing base;

[0010] A push plate is arranged along the X-axis and connected to the upper end face of the movable seat;

[0011] A salt structure simulation model is set between the fixed plate and the push plate, and is located on the upper surface of the fixed seat and the movable seat. The salt structure simulation model includes simulated sedimentary rock layers and simulated gypsum-salt layers.

[0012] A driving component is disposed at one end of the movable seat, used to drive the movable seat to move towards the fixed seat, so as to deform the salt structure simulation model located between the fixed plate and the push plate;

[0013] Monitoring components are used to acquire images of the salt structure simulation model when it deforms;

[0014] The gypsum-salt layer is constructed to extend along the X-axis direction. From bottom to top, the gypsum-salt layer includes a simulated brittle stratum, a simulated weak mudstone layer, and a simulated plastic gypsum-salt rock layer. The simulated sedimentary rock layer includes a subsalt layer located below the simulated gypsum-salt layer and a supersalt layer located above the simulated gypsum-salt layer.

[0015] The lower surfaces of the simulated brittle strata, simulated weak mudstone layer, and simulated plastic gypsum-salt rock layer are constructed as downwardly convex arc surfaces.

[0016] The first inclined plane has a first angle with the horizontal direction and a second angle with the X-axis direction. As the movable seat moves closer to the fixed seat, the salt structure simulation model undergoes shearing and extrusion deformation.

[0017] Preferably, the span of the first inclined plane in the Y-axis direction is greater than half the width of the salt structure simulation model.

[0018] Preferably, the monitoring component includes a first camera and a second camera, wherein the first camera acquires images of the salt structure simulation model during deformation along the X-axis, and the second camera acquires images of the salt structure simulation model during deformation along the Z-axis.

[0019] Preferably, the pre-salt layer and the over-salt layer are formed by laying dry quartz sand with a particle size of 100-400 micrometers, the simulated brittle stratum is formed by laying dry quartz sand with a particle size of 100-400 micrometers, the simulated weak mudstone layer is formed by laying micro glass beads with a particle size of 100-400 micrometers, the simulated plastic gypsum-salt rock layer is made of polymeric silicone resin material, the pre-salt layer includes multiple layers of quartz sand of different colors, and the simulated brittle stratum has a different color from the pre-salt layer.

[0020] Preferably, one side of the fixed plate is provided with a plurality of partition components extending toward the push plate and distributed along the X-axis. The partition components divide the salt structure simulation model into several parts. The partition components, the push plate, and the fixed plate form a laying space to accommodate the salt structure simulation model. The movable seat is provided with grooves corresponding to the distribution of the partition components.

[0021] Preferably, the separating component is provided with a support groove corresponding to the position of the salt layer, and the surface of the support groove is provided with a reflector. The reflector is tilted toward the first side of the separating component and is used to reflect the cross-sectional image of the salt structure simulation model in the laying space and the first side of the separating component in contact to the Z-axis direction.

[0022] Preferably, the tilt angle of the reflector is 45°.

[0023] Preferably, the laying space is provided with a plurality of first partitions and second partitions, and the space between each pair of first partitions is separated to form a filling space for accommodating each simulated structural layer in the simulated sedimentary rock layer, and the space between each pair of second partitions is separated to form a filling space for accommodating each simulated structural layer in the simulated gypsum salt layer, and the outer wall of the separating component is provided with positioning grooves for positioning the first partitions and second partitions.

[0024] Preferably, the upper end face of the separating component is provided with a plurality of material holes, and the side wall of the separating component is provided with a plurality of material discharge holes. Each material discharge hole corresponds to a filling space, and the material discharge hole is connected to a corresponding material hole for filling the predetermined filling space with material forming a structural layer.

[0025] The second aspect of this invention proposes a technical solution, a simulation method for experiments on thin interlayered compressive-torsional salt structures, comprising the following steps:

[0026] Step 1: Select simulation materials for the salt structure simulation model: The rock mechanical parameters of the collected salt structure under in-situ temperature and pressure conditions were tested using a high-temperature and high-pressure triaxial compression rheological test. Based on the lithological composition of the salt structure, the thickness of different rock types and their rheological properties, dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the lower and upper salt layers, dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the brittle strata, micro glass beads with a particle size of 100-400 micrometers were selected to simulate the weak mudstone layer, and polymerized silicone resin material was selected to simulate the plastic gypsum-salt rock layer.

[0027] Step 2: Establish a salt structure simulation model: Based on the materials selected in Step 1, lay each structural layer layer by layer from bottom to top;

[0028] Step 3: Drive the pusher plate to move closer to the fixed plate to compress the formed salt structure simulation model, causing the salt structure simulation model to undergo shearing and compression deformation.

[0029] Step 4: Place the first camera and the second camera in the direction of the simulated salt layer cross section and above the salt structure simulation model, and acquire images of the salt structure simulation model deforming in the X-axis and Z-axis directions at predetermined time intervals.

[0030] In step 2, the thickness of each structural layer is determined by filling a partition between every two structural layers. After the upper structural layer is laid, the partition between the upper and lower structural layers is removed.

[0031] Compared with existing technologies, the significant advantages of the experimental model for thin interlayered compressive-torsional salt structures proposed in this invention are:

[0032] (1) The experimental model of the present invention is based on the analysis of the rheological properties of the gypsum salt layer under in-situ temperature and pressure conditions of the target salt structure based on actual sample blocks. Suitable materials are selected to simulate and form an experimental model. The moving seat and push plate push the formed salt structure layer to form shear and extrusion deformation, so that the experimenters can obtain the deformation characteristics of the salt structure layer during the deformation process. This is beneficial for the experimenters to obtain the coupling and decoupling relationship of the differential deformation of the salt structure layer based on the experimental results.

[0033] (2) The inclined surface of the fixed seat of the present invention has an angle in the length direction of the simulated gypsum salt layer. When the movable seat and the fixed seat approach each other, shearing and extrusion deformation occur at different positions of the simulated gypsum salt layer, providing the experimenters with more materials with deformation characteristics.

[0034] (3) The present invention divides the salt structure simulation model into multiple mutually separated parts by a partition component. The partition component can reflect the cross-sectional image of the salt structure simulation model and the partition component from the X-axis direction to the Z-axis direction. It can also work with the partition plate to build each salt structure simulation model with a uniform size. This helps the experimenter to obtain more salt structure cross-sectional deformation characteristics and ensures that the characteristics are comparable, thus ensuring the accuracy and consistency of the obtained laws. Attached Figure Description

[0035] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings.

[0036] Figure 1 This is a schematic diagram of the experimental model of thin interlayered compressive-torsional salt structure shown in the first embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the salt structure simulation model shown in this invention.

[0038] Figure 3 This is a schematic diagram of the experimental model of thin interlayered compressive-torsional salt structure shown in the second embodiment of the present invention.

[0039] Figure 4 yes Figure 3 Top view.

[0040] Figure 5 This is a schematic diagram of the laying space formed between the two separating components shown in this invention.

[0041] Figure 6 This is a schematic diagram showing the distribution of the first and second partitions as illustrated in this invention.

[0042] Figure 7 This is a schematic diagram of the structure of the separator component shown in this invention.

[0043] Figure 8 This is a schematic diagram showing the distribution of the positioning grooves on the outer wall of the separator component as shown in this invention. Detailed Implementation

[0044] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0045] The project aims to study the Shizigou, Nanyishan, and Xianshuiquan structures in the Chaixi area. Based on high-quality 3D seismic data, detailed structural analysis, well logging curve analysis, drilling core description, and whole-rock mineral content testing, the project will determine the tectonic deformation patterns above and below the salt in the Shizigou, Nanyishan, and Xianshuiquan structures, identify the composition and thickness parameters of the gypsum-salt layers in the target structures, and analyze the rheological properties of gypsum-salt layers with different compositions under in-situ temperature and pressure conditions through high-temperature and high-pressure triaxial compression rheological experiments. Finally, suitable similar materials will be selected to construct a physical model of the compression-shear salt structure.

[0046] Thus, by simulating the differential deformation characteristics of the gypsum-salt layer under compression and torsion and the structures above and below the salt, the coupling and decoupling relationship between the gypsum-salt layer and the structures above and below the salt can be analyzed to reveal the control mechanism of different compression and torsion on coupling and decoupling.

[0047] In embodiments of the present invention, gypsum-salt layers refer to various landforms formed by salt layers during crustal movement. They are a special type of salt structure, primarily composed of minerals such as anhydrite or gypsum, and possess a dense porous structure and high salinity. The formation of gypsum-salt layers is typically associated with closed basins or lagoons, where salt accumulates in relatively isolated water bodies. Through long-term evaporation and salt migration, gypsum-salt layers are formed. In geological structures, gypsum-salt layers can form special landforms such as salt domes and salt diapirs, influencing crustal movement and deformation, thus significantly impacting the formation of oil and gas reservoirs and mineral resources. Simultaneously, gypsum-salt layers can also serve as caprocks to protect oil and gas reservoirs, reducing the escape and loss of oil and gas.

[0048] Thin interbedded layers refer to salt layers formed by the alternating deposition of thin layers of gypsum and halite, particularly two or more thin layers, each typically a few centimeters thick. The formation of thin interbedded layers is caused by changes in the sedimentary environment and exhibits distinct lithological and sedimentary structural characteristics.

[0049] Experimental Model of Thin Interlayered Compression-Torsion Salt Structure

[0050] First Embodiment

[0051] Combination Figure 1-2As shown, the first aspect of the present invention proposes an experimental model of thin interlayered compressive-torsional salt structure, including a fixed seat 10, a movable seat 20, a fixed plate 30, a push plate 40, and a salt structure simulation model.

[0052] Referring to the figure, the first end of the fixed seat 10 is provided with a first inclined surface 11, the movable seat 20 is disposed at the first end of the fixed seat 10 and has a second inclined surface that fits against the inclined surface 11, the fixed plate 30 is arranged along the X-axis direction and connected to the upper end surface of the fixed seat 10, and the push plate 40 is arranged along the X-axis direction and connected to the upper end surface of the movable seat 20.

[0053] In the example embodiment, the purpose of the experimental model is to cause the salt structure simulation model to undergo shear and compression deformation. Therefore, the salt structure simulation model is set between the fixed plate 30 and the push plate 40, and is located on the upper end face of the fixed seat 10 and the movable seat 20. The salt structure simulation model includes a simulated sedimentary rock layer 10a and a simulated gypsum salt layer 10b.

[0054] Thus, when the driving component at one end of the movable seat 20 drives the movable seat 20 to move closer to the fixed seat 10, the salt structure simulation model between the fixed plate 30 and the push plate 40 deforms. By acquiring images of the salt structure simulation model when it deforms through the monitoring component, the changes in the simulated structural layer under shear and compression deformation can be analyzed. By observing the deformation characteristics, the coupling and decoupling relationship between the salt structure and the structures above and below the salt can be analyzed.

[0055] In an optional embodiment, the fixed base 10 and the movable base 20 are made of transparent acrylic sheet material, while the fixed plate 30 and the push plate 40 are made of black plastic material.

[0056] Combination Figure 1-2 As shown, based on the characteristics of the salt structure, the gypsum-salt layer 10b is constructed to extend along the X-axis direction. From bottom to top, the gypsum-salt layer 10b includes a simulated brittle stratum 102, a simulated weak mudstone layer 103, and a simulated plastic gypsum-salt rock layer 104. The simulated sedimentary rock layer 10a includes a subsalt layer 101 located below the simulated gypsum-salt layer 10b and a supersalt layer 105 located above the simulated gypsum-salt layer 10b.

[0057] Among them, the plastic gypsum-salt rock layer 104 is formed by the interlayering of thin gypsum and halite layers, which can be called a thin interlayered salt structure.

[0058] Based on the lithological composition of the salt-structured gypsum-salt layer in the Chaixi area and its rheological properties under in-situ temperature and pressure conditions underground, this project selects suitable similar materials to construct a sand box physical model. For example, silica gel is selected to simulate plastic gypsum-salt rock, micro glass beads are selected to simulate weak mudstone, and dry quartz sand is selected to simulate carbonate rock, sandstone and other brittle strata.

[0059] The deformation characteristics follow the Mohr-Coulomb failure criterion. The tensile strength of dry, loose pure quartz sand is almost zero, with a particle size of 100-400 μm and a density of approximately 1500 kg / m³. 3 With an internal friction angle of 25°-30° and a bonding strength of approximately 200 Pa, it is suitable for simulating the brittle deformation behavior of shallow sedimentary rock layers in the Earth's crust. Polymer silicone resin (silicone for short) exhibits Newtonian fluid properties, and its performance is suitable for simulating brittle deformation behavior of shallow sedimentary rock layers in the Earth's crust at strain rates less than 3 × 10⁻⁶ Pa. -3 s -1 At that time, its dynamic viscosity was approximately 5 × 10⁻⁶. 4 Pa·s, close to the rheological characteristics of gypsum-salt rock, makes it an ideal material for simulating plastic gypsum-salt layers in nature. Microglass beads have an internal friction angle of approximately 25° and a plasticity between that of quartz sand and silica gel, making them suitable for simulating mudstone layers with lower strength.

[0060] In an optional embodiment, in order to facilitate the observation of the tectonic deformation process and its characteristics, the lower salt layer 101 and the upper salt layer 105 are interlayered with white and green quartz sand to simulate the actual strata, so that the deformation characteristics of the two adjacent structural layers can be clearly observed.

[0061] In a preferred embodiment, in order to highlight the deformation characteristics of the gypsum-salt layer 10b, the lower end faces of the simulated brittle strata 102, the simulated weak mudstone layer 103, and the simulated plastic gypsum-salt layer 104 are constructed as downwardly convex arc surfaces.

[0062] Furthermore, the first inclined plane 11 has a first angle with the horizontal direction and a second angle with the X-axis direction. As the movable seat 20 approaches the fixed seat 10, the salt structure simulation model undergoes shearing and extrusion deformation.

[0063] Thus, shear and compression deformations will occur at different locations along the width of the gypsum salt layer 10b, that is, shear and compression deformations will occur at different locations on the arc surface, which can reflect the deformation characteristics of structural layers with different inclination angles when shear and compression deformations occur.

[0064] In a preferred embodiment, the first inclined plane 11 has a span in the Y-axis direction greater than half the width of the salt structure simulation model. That is, the deformation occurs at a location exceeding half the width of the salt layer 10b.

[0065] Furthermore, the monitoring components include a first camera and a second camera. The first camera acquires images of the salt structure simulation model during deformation along the X-axis, and the second camera acquires images of the salt structure simulation model during deformation along the Z-axis.

[0066] Thus, during the extrusion process, the camera can acquire images of the salt layer 10b in real time as it undergoes shearing and extrusion deformation, which helps researchers analyze the coupling and decoupling relationship of the salt structure based on the changes in characteristics of the salt layer 10b throughout the entire deformation process.

[0067] Second Embodiment

[0068] Since the salt structure simulation model only exposes the outer side of the cross section facing the first camera, the first camera can only acquire the deformation image of the outermost salt structure. Since the first inclined plane 11 has a second angle with the X-axis direction, different deformations occur at different positions in the width direction of the salt layer 10b.

[0069] In order to obtain the deformation characteristics of these regions, further, combined with Figure 3-5 As shown, unlike Embodiment 1, the fixed plate 30 has a plurality of partition members 50 extending toward the push plate 40 and distributed along the X-axis on one side. The partition members 50 divide the salt structure simulation model into several parts. The partition members 50, the push plate 40 and the fixed plate 30 form a laying space 60 to accommodate the salt structure simulation model. The movable seat 20 has grooves 21 corresponding to the distribution of the partition members 50.

[0070] In an optional embodiment, the separator 50 is made of transparent plastic.

[0071] Thus, when the movable seat 20 and the push plate 40 move toward one side of the fixed plate 30, the movable seat 20 moves to the right and upwards at the same time, and the separating component 50 enters the groove 21 without interfering with the movement of the movable seat 20 and the push plate 40. The separating component 50 divides the salt structure simulation model into multiple independent regions, but the salt structure simulation model in each region has the same structure. The separating component 50 can change the image of one end face of the salt structure simulation model from the X-axis to the Z-axis direction, so that the second camera located on the Z-axis can obtain the cross-sectional image of each salt structure simulation model.

[0072] Specifically, in combination Figure 5 as well as Figure 7-8 As shown, the separating component 50 is provided with a support groove 51 corresponding to the position of the salt layer 10b. The surface of the support groove 51 is provided with a reflector 52. The reflector 52 is tilted towards the first side of the separating component 50. The reflector 52 is used to reflect the cross-sectional image of the salt structure simulation model in the laying space 60 and the first side of the separating component 50 in contact to the Z-axis direction.

[0073] The support groove 51 has arc-shaped grooves 511 on both sides to facilitate the experimenter to place the reflector 52 on the surface of the support groove 51 or remove it from the surface of the support groove 51.

[0074] Thus, the reflector 52 can reflect images of structural changes in the region of the gypsum salt layer 10b.

[0075] It should be understood that the salt structure simulation model is laid in the laying space 60 between the two separating components 50. The salt structure simulation model and the separating components 50 are attached to each other and have two cross sections. The reflector 52 is tilted toward one side of the separating component 50 to reflect the cross section image toward the reflector 52.

[0076] In a preferred embodiment, the tilt angle of the reflector 52 is 45°. Thus, the image reflected by the reflector 52 remains undistorted.

[0077] Thus, a dividing member 50 is set at predetermined intervals. The deformation position of the gypsum layer 10b is different at each dividing member 50. Therefore, only one camera needs to be set above the model to simultaneously capture images of the change process at different positions of the gypsum layer 10b.

[0078] Furthermore, in order to ensure that the construction of the simulation model in each laying space 60 is the same, multiple first partitions 61 and second partitions 62 are provided in the laying space 60. Each pair of first partitions 61 are separated to form a filling space to accommodate each simulated structural layer in the simulated sedimentary rock layer 10a, and each pair of second partitions 62 are separated to form a filling space to accommodate each simulated structural layer in the simulated gypsum salt layer 10b. The outer wall of the separating component 50 is provided with positioning grooves 55 for positioning the first partitions 61 and second partitions 62.

[0079] Thus, by positioning the first partition 61 and the second partition 62 by the partition component 50, each filling space has a fixed size. Therefore, the structural layer formed in the filling space also has a fixed size. This ensures that the structural layer of each simulated model has an ideal thickness and can accurately reflect the structural changes of the gypsum-salt layer 10b and the simulated sedimentary rock layer 10a under compression and torsion.

[0080] Model making process

[0081] In an optional embodiment, the upper end face of the partition component 50 is provided with a plurality of material holes 53, and the side wall of the partition component 50 is provided with a plurality of discharge holes 54. Each discharge hole 54 corresponds to a filling space, and the discharge hole 54 is connected to a corresponding material hole 53 for filling the predetermined filling space with material forming a structural layer.

[0082] In this way, the model created by filling the space with material can ensure that the structure of each layer meets the ideal dimensions.

[0083] Combination Figure 6As shown, in a specific embodiment, the simulated sedimentary rock layer 10a comprises seven layers, of which the lower six layers are the subsalt layer 101 and the uppermost layer is the supersalt layer 105, with each two layers separated by a first partition 61; the gypsum-salt layer 10b comprises three layers, from bottom to top: a simulated brittle stratum 102, a simulated weak mudstone layer 103, and a simulated plastic gypsum-salt rock layer 104, with each two layers separated by a second partition 62.

[0084] Optionally, a total of 8 first partitions 61 are provided, with three first partitions 61 located below the second partition 62, four first partitions 61 located on both sides of the second partition 62, and the remaining first partition 61 located above the second partition 62. One end of each first partition 61 is connected to the fixed plate 30 or the push plate 40.

[0085] Optionally, the first partition 61 and the second partition 62 are stainless steel sheets with a thickness of 0.5-1mm. The first partition 61 and the second partition 62 are inserted into the positioning groove 55 so that each pair of first partitions 61 has a specific position.

[0086] In an optional embodiment, the thickness of the positioning groove 55 is the same as the thickness of the first partition 61 and the second partition 62, and the depth of the positioning groove 55 is less than 1 mm.

[0087] The fixed plate 30 and the push plate 40 are provided with slits at corresponding heights to accommodate the first partition 61. The slits are made of two rubber blocks, and the first partition 61 can be pulled out from the slits.

[0088] In a specific embodiment, the model is placed on a vibratory feeder, and green quartz sand is added through the feed hole 53. The green quartz sand is discharged from the discharge hole 54 of the first layer, filling the space below the bottom first partition 61. Due to the vibration of the vibratory feeder, the green quartz sand fills the space below the first partition 61. Then, white quartz sand is added through the feed hole 53, and the white quartz sand is discharged from the discharge hole 54 of the second layer, filling the space above the bottom first partition 61. Due to the vibration of the vibratory feeder, the white quartz sand fills the space of the second layer. This process is repeated to fill the third, fourth, fifth, and sixth layers of space in sequence. A salt sub-layer 101 with alternating green-white-green-white-green-white layers is formed. Yellow quartz sand is then filled into the first layer space separated by the second partition 62 to form a simulated brittle stratum 102. After filling, micro glass beads are filled into the second layer space separated by the second partition 62 to form a simulated weak mudstone layer 103. Then, all the first partitions 61 and the second partitions 62 are removed. A pre-shaped polymeric silicone resin layer is then placed on top of the micro glass beads to simulate a plastic gypsum-salt rock layer 104. Another first partition 61 is inserted on top of the polymeric silicone resin layer. Finally, a predetermined thickness of white quartz sand is laid on top of the first partition 61 to complete the salt structure simulation model.

[0089] Simulation Methods for Experiments on Thin Interlayered Compression-Twist Salt Structures

[0090] The second aspect of this invention proposes a technical solution, a simulation method for experiments on thin interlayered compressive-torsional salt structures, comprising the following steps:

[0091] Step 1: Select simulation materials for the salt structure simulation model: The rock mechanical parameters of the collected salt structure under in-situ temperature and pressure conditions were tested using a high-temperature and high-pressure triaxial compression rheological test. Based on the lithological composition of the salt structure, the thickness of different rock types and their rheological properties, dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the lower salt layer 101 and the upper salt layer 105. Dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the brittle strata 102. Micro glass beads with a particle size of 100-400 micrometers were selected to simulate the weak mudstone layer 103. Polymerized silicone resin material was selected to simulate the plastic gypsum-salt rock layer 104.

[0092] Step 2: Establish a salt structure simulation model: Based on the materials selected in Step 1, lay each structural layer layer by layer from bottom to top;

[0093] Step 3: Drive the push plate 40 to move closer to the fixed plate 30 to squeeze the formed salt structure simulation model, causing the salt structure simulation model to undergo shearing and extrusion deformation.

[0094] Step 4: Place the first camera and the second camera in the direction of the simulated salt layer 10b section and above the salt structure simulation model, and acquire images of the salt structure simulation model deforming in the X-axis and Z-axis directions at predetermined time intervals.

[0095] In step 2, the thickness of each structural layer is determined by filling a partition between every two structural layers. After the upper structural layer is laid, the partition between the upper and lower structural layers is removed.

[0096] Specifically, in step 1, drilling cores of different lithologies in the upper part of the Ganchaigou Formation under the Shizigou, Nanyishan, and Xianshuiquan structures in the Chaixi area were collected, including pure salt rock, gypsum-salt rock, gypsum-salt mudstone and carbonate rock, and mudstone and carbonate rock samples. Following the sample specifications for triaxial compression rheology experiments, the drilling cores were prepared into standard cylinders of 25×50mm, with five samples prepared for each lithology. Based on the in-situ temperature and pressure conditions at different depths in the Chaixi area (e.g., 90°C at a depth of 3km, confining pressure of 50MPa, data provided by the Qinghai Oilfield Exploration and Development Research Institute from steady-state temperature and pressure tests of the drilling system), the temperature and pressure of the pressure chamber were set using a pressure chamber temperature control system and a high-precision confining pressure servo control system. Then, a temperature-stress-seepage fully coupled triaxial compression rheometer was used to conduct triaxial compression rheology experiments on the rock samples under in-situ temperature and pressure conditions. During the experiment, a deformation measurement module was used to monitor the deformation and failure process of the rock samples in real time. Based on the experimental results, rock mechanics parameters such as stress-strain curves, creep curves, axial failure stress, elastic modulus, Poisson's ratio, shear strength, cohesion, and internal friction angle of gypsum-salt rock samples with different compositions were calculated, and the rheological properties of gypsum-salt rock samples with different compositions under in-situ underground temperature and pressure conditions were analyzed.

[0097] Finally, it was determined that dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the lower salt layer 101 and the upper salt layer 105, dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the brittle stratum 102, micro glass beads with a particle size of 100-400 micrometers were selected to simulate the weak mudstone layer 103, and polymerized silicone resin material was selected to simulate the plastic gypsum-salt rock layer 104.

[0098] The deformation characteristics follow the Mohr-Coulomb failure criterion. The tensile strength of dry, loose pure quartz sand is almost zero, with a particle size of 100-400 μm and a density of approximately 1500 kg / m³. 3 With an internal friction angle of 25°-30° and an adhesion strength of approximately 200 Pa, it is suitable for simulating the brittle deformation behavior of shallow sedimentary rock layers in the Earth's crust. Polymer silicone resin (silicone for short) exhibits Newtonian fluid properties, and its adhesion is within the range of 3 × 10⁻⁶ Pa at strain rates less than 10⁻⁶ Pa. -3 s -1 At that time, its dynamic viscosity was approximately 5 × 10⁻⁶. 4Pa·s, close to the rheological characteristics of gypsum-salt rock, makes it an ideal material for simulating plastic gypsum-salt layers in nature. Microglass beads have an internal friction angle of approximately 25° and a plasticity between that of quartz sand and silica gel, making them suitable for simulating mudstone layers with lower strength.

[0099] In step 2, the model is placed on the vibratory feeder. Green quartz sand is added through the feed hole 53 and discharged from the discharge hole 54 of the first layer. The green quartz sand fills the space below the first partition 61 at the bottom layer. Due to the vibration of the vibratory feeder, the green quartz sand fills the space below the first partition 61. Then, white quartz sand is added through the feed hole 53 and discharged from the discharge hole 54 of the second layer. The white quartz sand fills the space above the first partition 61 at the bottom layer. Due to the vibration of the vibratory feeder, the white quartz sand fills the space of the second layer. This process is repeated to fill the third, fourth, fifth, and sixth layers of space, forming a model. A salt sub-layer 101 with alternating green-white-green-white-green-white layers is formed. Yellow quartz sand is then filled into the first layer space separated by the second partition 62 to form a simulated brittle stratum 102. After filling, micro glass beads are filled into the second layer space separated by the second partition 62 to form a simulated weak mudstone layer 103. Then, all the first partitions 61 and the second partitions 62 are removed. A pre-shaped polymerized silicone resin layer is then placed on top of the micro glass beads to simulate a plastic gypsum-salt rock layer 104. Another first partition 61 is inserted on top of the polymerized silicone resin layer. Finally, a predetermined thickness of white quartz sand is laid on top of the first partition 61 to complete the salt structure simulation model.

[0100] In step 3, the electric telescopic rod is used to push the push plate 40 slowly toward the fixed plate 30 to compress the formed salt structure simulation model, causing the salt structure simulation model to undergo shearing and compression deformation.

[0101] In step 4, the deformation process of the model is photographed by cameras on the top and sides of the model, especially the deformation of the salt layer 10b. The side cameras can photograph the deformation of the outermost salt structure and the overall deformation of the salt structure above and below the salt. The top camera can photograph the deformation of the top of the model and the deformation of the salt structure reflected by the reflector 52, so as to obtain the characteristic deformation of the salt structure in different parts and analyze the coupling and decoupling relationship between the salt structure and the salt structure above and below the salt under the action of compression and torsion.

[0102] In conjunction with the above embodiments, the experimental model of the embodiments proposed in this invention is based on the analysis of the rheological properties of the gypsum salt layer under in-situ temperature and pressure conditions of the actual sample block of the target salt structure. Appropriate materials are selected to simulate and form an experimental model. The moving seat and push plate push the formed salt structure layer to form shear and extrusion deformation, so that the experimenter can obtain the deformation characteristics of the salt structure layer during the deformation process. This is beneficial for the experimenter to obtain the coupling and decoupling relationship of the differential deformation of the salt structure layers based on the experimental results.

[0103] In the experimental model design of this invention embodiment, the inclined surface of the fixed seat has an angle in the length direction of the simulated gypsum layer. When the movable seat and the fixed seat approach each other, shearing and extrusion deformation occur at different positions of the simulated gypsum layer, providing the experimenters with more material with deformation characteristics.

[0104] In the experimental model design of this invention, the salt structure simulation model is divided into multiple mutually separated parts by a partition component. The partition component can reflect the cross-sectional image of the salt structure simulation model and the partition component from the X-axis direction to the Z-axis direction. It can also work with the partition plate to build each salt structure simulation model to a uniform size. This helps the experimenters obtain more cross-sectional deformation features of the salt structure and ensures that the features are comparable, thus ensuring the accuracy of the obtained patterns.

[0105] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. An experimental model for thin interlayered compressional twisted salt structures, characterized in that, include: A fixing seat (10) is provided at its first end with a first inclined surface (11); The movable seat (20) is disposed at the first end of the fixed seat (10) and has a second inclined surface that fits against the inclined surface (11); A fixing plate (30) is arranged along the X-axis and connected to the upper end face of the fixing seat (10); A push plate (40) is arranged along the X-axis and connected to the upper end face of the movable seat (20); A salt structure simulation model is set between the fixed plate (30) and the push plate (40), and is located on the upper surface of the fixed seat (10) and the movable seat (20). The salt structure simulation model includes a simulated sedimentary rock layer (10a) and a simulated gypsum salt layer (10b). A driving component is provided at one end of the movable seat (20) to drive the movable seat (20) to move toward the fixed seat (10), so that the salt structure simulation model between the fixed plate (30) and the push plate (40) is deformed. Monitoring components are used to acquire images of the salt structure simulation model when it deforms; The gypsum-salt layer (10b) is constructed to extend along the X-axis direction. The gypsum-salt layer (10b) includes, from bottom to top, a simulated brittle stratum (102), a simulated weak mudstone layer (103), and a simulated plastic gypsum-salt rock layer (104). The simulated sedimentary rock layer (10a) includes a subsalt layer (101) located below the simulated gypsum-salt layer (10b) and a supersalt layer (105) located above the simulated gypsum-salt layer (10b). The lower surfaces of the simulated brittle strata (102), the simulated weak mudstone layer (103), and the simulated plastic gypsum-salt rock layer (104) are constructed as downwardly convex arc surfaces. The first inclined plane (11) has a first angle with the horizontal direction and a second angle with the X-axis direction. When the movable seat (20) moves closer to the fixed seat (10), the salt structure simulation model undergoes shearing and extrusion deformation.

2. The experimental model of thin interlayered compressive-torsional salt structure according to claim 1, characterized in that, The first inclined plane (11) has a span in the Y-axis direction that is greater than half the width of the salt structure simulation model.

3. The experimental model of thin interlayered compressive-torsional salt structure according to claim 1, characterized in that, The monitoring component includes a first camera and a second camera. The first camera acquires images of the salt structure simulation model during deformation along the X-axis, and the second camera acquires images of the salt structure simulation model during deformation along the Z-axis.

4. The experimental model of thin interlayered compressive-torsional salt structure according to claim 1, characterized in that, The pre-salt layer (101) and the over-salt layer (105) are formed by laying dry quartz sand with a particle size of 100-400 micrometers. The simulated brittle stratum (102) is formed by laying dry quartz sand with a particle size of 100-400 micrometers. The simulated weak mudstone layer (103) is formed by laying micro glass beads with a particle size of 100-400 micrometers. The simulated plastic gypsum-salt rock layer (104) is made of polymeric silicone resin. The pre-salt layer (101) includes multiple layers of quartz sand of different colors. The simulated brittle stratum (102) is different in color from the pre-salt layer (101).

5. The experimental model of thin interlayered compressional twisted salt structure according to any one of claims 1-4, characterized in that, The fixed plate (30) has a plurality of partition components (50) extending toward the push plate (40) and distributed along the X-axis on one side. The partition components (50) divide the salt structure simulation model into several parts. The partition components (50), the push plate (40), and the fixed plate (30) form a laying space (60) to accommodate the salt structure simulation model. The movable seat (20) has grooves (21) corresponding to the distribution of the partition components (50).

6. The experimental model of thin interlayered compressive-torsional salt structure according to claim 5, characterized in that, The separating component (50) is provided with a support groove (51) corresponding to the position of the salt layer (10b). The surface of the support groove (51) is provided with a reflector (52). The reflector (52) is tilted toward the first side of the separating component (50). The reflector (52) is used to reflect the cross-sectional image of the salt structure simulation model in the laying space (60) in contact with the first side of the separating component (50) to the Z-axis direction.

7. The experimental model of thin interlayered compressive-torsional salt structure according to claim 6, characterized in that, The tilt angle of the reflector (52) is 45°.

8. The experimental model of thin interlayered compressive-torsional salt structure according to claim 5, characterized in that, The laying space (60) is provided with a plurality of first partitions (61) and second partitions (62). Each pair of first partitions (61) is separated to form a filling space for accommodating each simulated structural layer in the simulated sedimentary rock layer (10a). Each pair of second partitions (62) is separated to form a filling space for accommodating each simulated structural layer in the simulated gypsum salt layer (10b). The outer wall of the separating component (50) is provided with positioning grooves (55) for positioning the first partitions (61) and second partitions (62).

9. The experimental model of thin interlaminated compressional salt structure according to claim 7, characterized in that, The upper end face of the partition component (50) is provided with a plurality of material holes (53), and the side wall of the partition component (50) is provided with a plurality of discharge holes (54). Each discharge hole (54) corresponds to a filling space. The discharge hole (54) is connected to a corresponding material hole (53) and is used to fill the predetermined filling space with material forming a structural layer.

10. A simulation method for thin interlayered compressional-torsional salt structures, characterized in that, Includes the following steps: Step 1: Select simulation materials for the salt structure simulation model: The rock mechanical parameters of the collected salt structure under in-situ temperature and pressure conditions were tested by high temperature and high pressure triaxial compression rheological test. According to the lithological composition of the salt structure, the thickness of different rock types and their rheological properties, dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the lower salt layer (101) and upper salt layer (105). Dry quartz sand with a particle size of 100-400 micrometers was selected to simulate the brittle strata (102). Micro glass beads with a particle size of 100-400 micrometers were selected to simulate the weak mudstone layer (103). Polymerized silicone resin material was selected to simulate the plastic gypsum-salt rock layer (104). Step 2: Establish a salt structure simulation model: Based on the materials selected in Step 1, lay each structural layer layer by layer from bottom to top; Step 3: Drive the push plate (40) to move closer to the fixed plate (30) to squeeze the formed salt structure simulation model, causing the salt structure simulation model to undergo shearing and extrusion deformation; Step 4: Place a first camera and a second camera in the direction of the simulated salt layer (10b) cross section and above the salt structure simulation model, and acquire images of the salt structure simulation model deforming in the X-axis and Z-axis directions at predetermined time intervals. In step 2, the thickness of each structural layer is determined by filling a partition between every two structural layers. After the upper structural layer is laid, the partition between the upper and lower structural layers is removed.

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