Visual simulation device for crack propagation of multi-thin interbed crossing fracturing

Abstract

The invention belongs to the technical field of oil development of thin interreservoirs, and particularly relates to a multi-thin interbed crossing fracturing crack propagation visual simulation device, and a crossing fracturing experiment is simulation of exploiting a multi-thin interbed by adopting a crossing fracturing process. The multi-thin interbed crossing fracturing crack propagation visual simulation device comprises a confining pressure assembly and a crack pressure assembly, the confining pressure assembly is used for simulating ground stress conditions, and the crack pressure assembly is used for simulating net pressure in cracks. In the application, the confining pressure assembly comprises a plurality of side confining pressure pieces which are arranged at intervals along the longitudinal direction, and different crustal stresses are applied to different rock stratums through the plurality of side confining pressure pieces to simulate the crustal stress difference between different rock stratums in a plurality of thin interreservoir stratums along the horizontal direction, so that the stress condition in a crossing fracturing experiment better conforms to the actual production condition; therefore, the authenticity of the cross-layer fracturing experiment is improved, support is provided for design, numerical simulation and the like of the cross-layer fracturing technology, and the progress of the cross-layer fracturing experiment towards the refinement direction is promoted.

Description

Technical Field

[0001] The present application belongs to the technical field of thin interlayer oil development, and specifically relates to a multi-thin interlayer cross-layer fracturing crack expansion visualization simulation device. Background Art

[0002] There is huge potential for the development of unconventional oil and gas resources in China. Reservoirs composed of multiple lithologies superimposed on each other are called multi-thin interlayer reservoirs. They are characterized by thin single-layer thickness and many vertical layers of sandstone reservoirs containing oil and gas resources, but are separated by interlayers such as mudstone and tuff that do not contain oil and gas resources. At present, when horizontal well fracturing is used, it is usually considered to use through-layer fracturing technology to form cracks of sufficient height in the vertical direction, so that the cracks penetrate multiple sandstone reservoirs in between, realize vertical multi-layer coordinated exploitation, and increase the oil and gas production of a single well.

[0003] With the successful application of trans-layer fracturing in multiple thin interlayer reservoirs and the increasing difficulty of exploitation of multiple thin interlayer reservoirs, the necessity of studying the interaction between artificial fractures and interlayer weak planes has gradually increased. Artificial fractures and interlayer weak planes may present interaction modes such as penetration, deflection, deflection and penetration, and deflection followed by penetration under different stress conditions and net pressures in the fractures, which have a decisive influence on the fracture height. Traditional rock direct shear strength testers, Brazilian splitting tests, three-point bending tests, etc. cannot restore the horizontal ground stress difference between the reservoir and the interlayer, that is, in the simulation experiment, the horizontal ground stress of each rock layer in the thin interlayer is set to the same value, resulting in the experimental results being unable to accurately reflect the actual situation. Summary of the invention

[0004] The purpose of this application is to provide a visual simulation device for fracture propagation in multiple thin interlayer cross-layer fracturing, aiming to improve the authenticity of cross-layer fracturing experiments.

[0005] In order to achieve the above-mentioned objectives, the present application provides, on the one hand, a visual simulation device for fracture propagation through multiple thin interlayer fracturing.

[0006] In some embodiments, the test sample includes a plurality of rock layers stacked in a longitudinal direction and extending in a transverse direction, a pre-groove is formed on the rock layer at the bottom layer, and the multi-thin interlayer cross-layer fracturing crack extension visualization simulation device includes:

[0007] a confining pressure assembly, used for applying confining pressure to the test sample and comprising a plurality of side confining pressure members arranged at intervals along the longitudinal direction, wherein the side confining pressure members are arranged in one-to-one correspondence with the rock formations; and

[0008] A crack pressure assembly is plugged into and matched with the pre-groove and is used to apply an outward force to the pre-groove.

[0009] In some embodiments, the side containment member comprises:

[0010] A confining pressure driving unit, providing a driving force along the lateral direction;

[0011] The confining pressure acting part is drivingly connected to the confining pressure driving part, and the confining pressure acting part extends along the longitudinal direction, and the longitudinal length of the confining pressure acting part is consistent with the longitudinal height of the corresponding rock formation.

[0012] In some embodiments, the confining pressure assembly further comprises a top confining pressure member arranged on the rock layer at the topmost layer, and an action direction of the top confining pressure member is perpendicular to an action direction of the side confining pressure member.

[0013] In some embodiments, the fracture pressure assembly includes a moving part and an action protrusion, the action protrusion is plug-fitted with the pre-groove, and the moving part is used to drive the action protrusion to apply a force to the pre-groove.

[0014] In some embodiments, the outer contour of the active protrusion is consistent with the inner contour of the pre-groove.

[0015] In some embodiments, the movable member includes two movable acting parts symmetrically arranged along the transverse direction, and the two movable acting parts can move away from each other along the transverse direction. The acting protrusion includes two acting embedded parts symmetrically arranged along the transverse direction, and the two acting embedded parts are connected to the two movable acting parts in a one-to-one correspondence.

[0016] In some embodiments, the multi-thin interlayer cross-layer fracturing crack extension visualization simulation device also includes a shell, in which a test sample installation cavity and a moving part installation cavity connected to the test sample installation cavity along the longitudinal direction are formed, and the two moving action parts can move in the moving part installation cavity along the transverse direction.

[0017] In some embodiments, the action embedding portion is arranged on one side of the movable action portion along the longitudinal direction, and a limiting action portion is provided on the other side of the movable action portion along the longitudinal direction. A limiting protrusion is formed on the cavity wall of the movable part installation cavity along the longitudinal direction toward the movable action portion, and the limiting protrusion is located on the outer side of the limiting action portion along the transverse direction and forms a limiting groove together with the limiting action portion and the movable action portion. The crack pressure assembly also includes a limiting member, which can cooperate with the limiting groove in a limiting manner.

[0018] In some embodiments, a driving portion is provided at an end portion of the moving portion along the lateral direction, and the fracture pressure assembly further comprises a driving member, and the driving member is used to apply an outward force along the lateral direction to the driving portion.

[0019] In some embodiments, a driving groove is formed between the driving action portion and the limiting protrusion, at least one inner side surface of the driving groove is an inclined surface, and the driving member includes a wedge-shaped portion embedded in the driving groove and a pushing portion for applying a longitudinal force to the wedge-shaped portion, and the inclined surface of the wedge-shaped portion is in contact with the inclined surface of the driving groove.

[0020] Through the above technical solution, the multi-thin interlayer cross-layer fracturing crack extension visualization simulation device provided by the present application has the following beneficial effects:

[0021] The test sample includes a plurality of rock layers stacked in the longitudinal direction and extending in the transverse direction, and a pre-groove extending in the longitudinal direction is formed on the rock layer at the bottom layer. When conducting a through-layer fracturing experiment, the test sample is placed in a multi-thin interlayer through-layer fracturing crack extension visualization simulation device, and a confining pressure component is used to apply confining pressure to the test sample to simulate all the horizontal ground stresses of each rock layer, and a force is applied to the pre-groove through the crack pressure component to simulate the net pressure in the crack that causes the crack to crack. In the present application, the confining pressure component includes a plurality of side confining pressure members, and different ground stresses are applied to different rock layers through the plurality of side confining pressure members to simulate the difference in ground stresses in the horizontal direction between different rock layers of the multi-thin interlayer reservoir, so that the experimental results of the through-layer fracturing experiment are more in line with the actual production situation, thereby improving the authenticity of the through-layer fracturing experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without creative work. In the drawings:

[0023] Figure 1 It is a schematic diagram of a test sample in a specific embodiment of the present application;

[0024] Figure 2 A three-dimensional diagram of a visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to a specific embodiment of the present application;

[0025] Figure 3 It is a front view of a visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to a specific embodiment of the present application;

[0026] Figure 4 for Figure 3 Middle AA section;

[0027] Figure 5 for Figure 3 Middle BB section;

[0028] Figure 6 A side view of a multi-thin interlayer cross-layer fracturing crack extension visualization simulation device according to a specific embodiment of the present application;

[0029] Figure 7 for Figure 6 Middle CC section;

[0030] Figure 8 for Figure 7 A magnified view of part D in the middle;

[0031] Fig. 9 It is a schematic diagram of a side confining and pressing member (top confining and pressing member) according to a specific embodiment of the present application;

[0032] Fig.10 It is a schematic diagram of a moving action part according to a specific embodiment of the present application;

[0033] Fig.11 It is a schematic diagram of the installation of a test sample and a visual simulation device for fracture extension of multiple thin interlayer cross-layer fracturing according to a specific embodiment of the present application.

[0034] Description of Reference Numerals

[0035] 100. Visual simulation device for fracture propagation of multiple thin interlayer interlayer fracturing; 200. Test sample; 210. Pre-grooving; 220. Guide groove; 1. Top confining pressure member; 2. Side confining pressure member; 21. Confining pressure driving part; 22. Confining pressure action part; 3. Moving member; 31. Moving action part; 32. Driving action part; 33. Limiting action part; 4. Action protrusion; 41. Action embedding part; 5. Shell; 51. Cover plate; 52. Limiting protrusion; 53. Limiting groove; 54. Driving groove; 55. Plug interface; 6. Driving member; 7. Limiting member. DETAILED DESCRIPTION

[0036] The specific implementation of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present application, and is not used to limit the present application.

[0037] The following describes the noun part of the multi-thin interlayer cross-layer hydraulic fracturing crack propagation visualization simulation device 100 according to the present application with reference to the accompanying drawings.

[0038] Multiple interlayer reservoirs are formed by the overlapping of multiple rock layers with different lithologies. Multiple interlayer reservoirs include reservoirs containing oil and gas resources and interlayers without oil and gas resources. For the exploitation of multiple interlayer reservoirs, the through-layer fracturing process is used to form cracks of sufficient height in the vertical direction and make the cracks penetrate multiple reservoirs separated by interlayers, so as to realize the coordinated exploitation of multiple reservoirs and thus increase the oil and gas production of a single well.

[0039] The through-layer fracturing experiment is used to simulate the process of exploiting multiple thin interlayer reservoirs using the through-layer fracturing process. The through-layer fracturing experiment requires the use of a test sample 200 and a visual simulation device 100 for the expansion of multiple thin interlayer through-layer fracturing cracks, wherein the test sample 200 is used to simulate multiple thin interlayer reservoirs, and the visual simulation device 100 for the expansion of multiple thin interlayer through-layer fracturing cracks is used to simulate the ground stress of multiple thin interlayer reservoirs and the force of the through-layer fracturing process on the cracks (net pressure in the cracks).

[0040] like Figure 1 As shown, the test sample 200 includes a plurality of rock layers stacked in the longitudinal direction and extending in the transverse direction, and a pre-groove 210 extending in the longitudinal direction is formed on the rock layer at the bottom layer. Specifically, the test sample 200 includes at least two stacked rock layers with different lithologies. According to the situation of multiple thin inter-reservoirs to be simulated, one of the rock layers can be selected as a reservoir layer and the other as a rock layer, and the pre-groove 210 is set on the rock layer to simulate the formation of cracks.

[0041] like Figures 2 to 8 As shown, in a specific embodiment of the present application, a visual simulation device 100 for fracture extension by multi-thin interlayer fracturing includes a confining pressure assembly and a fracture pressure assembly, wherein the confining pressure assembly is used to apply confining pressure to a test sample 200 and includes a plurality of side confining pressure members 2 arranged at intervals along the longitudinal direction, and the side confining pressure members 2 are arranged one-to-one in correspondence with the rock formations; the fracture pressure assembly is plugged into and matched with the pre-groove 210 and is used to apply an outward force to the pre-groove 210.

[0042] In the actual production process, artificial fractures will present different interaction modes under different stress conditions, such as penetration, deflection, deflection and penetration, deflection and then penetration, etc., and different interaction modes will cause the extension direction of the formed artificial fractures to be different. In the present application, different side confining pressures are applied to different rock formations by different side confining pressure members 2 to simulate the horizontal ground stress differences between different rock formations in multiple thin interlayer reservoirs, so that the stress conditions in the through-layer fracturing experiment are more in line with the actual production situation, thereby improving the authenticity of the results of the through-layer fracturing experiment.

[0043] Under real formation and ground stress conditions, through-layer fracturing experiments can obtain the real interaction mode between artificial fractures and interlayer weak surfaces (interface between reservoir and rock formation) (common ones include fractures passing through interlayer weak surfaces, fractures turning at interlayer weak surfaces, fractures turning at interlayer weak surfaces first and then passing through interlayer weak surfaces, etc.). The real interaction mode can accurately evaluate the morphology of artificial fractures under specific formation and ground stress conditions, so as to provide basis and guidance for the design of through-layer fracturing technology and numerical simulation.

[0044] It should be noted that in the specific embodiments of the present application, unless otherwise stated, the “vertical direction” used refers to the “up-down direction”, and the “lateral direction” refers to the “left-right direction”. In other words, the test sample 200 includes a plurality of rock layers stacked in the up-down direction and extending in the left-right direction. It can be seen that the height direction of the rock layer is the up-down direction, the length direction of the rock layer is the left-right direction, and correspondingly, the thickness direction of the rock layer is the front-back direction. The “up-down direction”, “left-right direction” and “front-back direction” are the directions indicated by the arrows in the figure.

[0045] For convenience of explanation, in an exemplary embodiment of the present application, the test sample 200 is a cube and includes two rock layers stacked in an up-and-down direction and extending in a left-and-right direction.

[0046] In some embodiments, the confining pressure assembly further includes a top confining pressure member 1 arranged on the topmost rock layer, and the action direction of the top confining pressure member 1 is perpendicular to the action direction of the side confining pressure member 2 .

[0047] Specifically, the top confining pressure member 1 is used to apply confining pressure to the test sample 200 in the up-down direction, and the side confining pressure member 2 is used to apply confining pressure to the test sample 200 in the left-right direction. The top confining pressure member 1 and the side confining pressure member 2 are used to simulate the real ground stress conditions of multiple thin inter-reservoir layers, so that the experimental results are more in line with actual working conditions.

[0048] Furthermore, a side confining pressure piece 2 is provided on the left and right sides of each rock formation, respectively. The side confining pressure piece 2 on the left side is used to apply pressure to the left side of the rock formation, and the side confining pressure piece 2 on the right side is used to apply pressure to the right side of the rock formation.

[0049] In an exemplary embodiment of the present application, there are four side confining pressure members 2, which are symmetrically arranged in pairs on the left and right sides of the test sample 200. The side confining pressure members 2 located above only apply pressure to the rock formation located above, and the side confining pressure members 2 located below only apply pressure to the rock formation located below; there is one top confining pressure member 1, which is set above the test sample 200 and applies pressure to the upper surface of the rock formation located above.

[0050] Those skilled in the art can understand that, the number of the above-mentioned side confining pressure members 2 is only the minimum number that can apply pressure to the test sample 200, and the number of the side confining pressure members 2 located on the same side of the same rock formation can be multiple, and it is only necessary to ensure that the pressure applied by all the side confining pressure members 2 located on the same side of the same rock formation is the same; the number of the above-mentioned top confining pressure members 1 is only the minimum number that can apply pressure to the test sample 200, and it can also be multiple, and it is only necessary to ensure that the pressure applied by all the top confining pressure members 1 is the same.

[0051] like Fig. 9As shown, in some embodiments, the side confining pressure member 2 includes a confining pressure driving part 21 and a confining pressure acting part 22, wherein the confining pressure driving part 21 provides a driving force in the lateral direction; the confining pressure acting part 22 is drivingly connected to the confining pressure driving part 21, the confining pressure acting part 22 extends in the longitudinal direction, and the longitudinal length of the confining pressure acting part 22 is consistent with the longitudinal height of the corresponding rock formation.

[0052] Specifically, the length of the confining pressure acting part 22 in the up-down direction is equal to the height of the corresponding rock formation in the up-down direction, the width of the confining pressure acting part 22 in the front-to-back direction is equal to the thickness of the corresponding rock formation in the front-to-back direction, and the confining pressure driving part 21 provides a driving force in the left-right direction to the confining pressure acting part 22. By setting the confining pressure acting part 22 to be consistent in shape with the side surface of the rock formation, the side surface of the rock formation is evenly pressurized, thereby better simulating all the ground stresses of the actual rock formation, thereby improving the reliability of the results of the through-layer fracturing experiment.

[0053] Furthermore, the top confining pressure member 1 has the same structure as the side confining pressure member 2 and is also consistent with the shape of the top surface of the rock formation so that the top surface of the rock formation is evenly compressed.

[0054] In the exemplary embodiment of the present application, the confining pressure driving part 21 is a hydraulic cylinder, the confining pressure acting part 22 is a flat jack, the hydraulic cylinder includes a piston and an oil pump, the piston is used to push the flat jack to extend and retract in the left and right directions, and the oil pump is used to supply oil to the piston. Among them, the structure and working principle of the hydraulic cylinder and the flat jack are well known to those skilled in the art, and do not belong to the core improvement part of the present application, so they are not repeated here.

[0055] For convenience of explanation, in an exemplary embodiment of the present application, the pre-groove 210 is disposed on a rock formation located below and an opening of the pre-groove 210 faces downward.

[0056] The through-layer fracturing process requires artificial destruction of multiple thin interlayers to form cracks of sufficient height along the vertical direction, which naturally requires simulation research on the forces that produce cracks. The forces that produce cracks are called net pressure inside the cracks.

[0057] like Figure 7 As shown, in some embodiments, the fracture pressure assembly includes a moving part 3 and an action protrusion 4, the action protrusion 4 is plugged into and matched with the pre-groove 210, and the moving part 3 is used to drive the action protrusion 4 to apply a force to the pre-groove 210.

[0058] Since the action protrusion 4 is inserted into the pre-groove 210 and applies a force to the inner surface of the pre-groove 210, but does not apply a force to the bottom and side surfaces of the rock formation, the force applied by the action protrusion 4 to the pre-groove 210 is almost equal to the net pressure in the crack. It can be seen that the crack pressure component can simulate the net pressure in the crack of the through-layer fracturing process, thereby improving the reliability of the results of the through-layer fracturing experiment and promoting the progress of the through-layer fracturing experiment towards refinement.

[0059] Preferably, the outer contour of the action protrusion 4 is consistent with the inner contour of the pre-groove 210. It can be seen that the force exerted by the action protrusion 4 on the pre-groove 210 is closer to the net pressure in the crack, thereby achieving a better simulation effect.

[0060] like Fig.10 As shown, further, the moving member 3 includes two moving action parts 31 arranged symmetrically in the transverse direction, and the two moving action parts 31 can move away from each other in the transverse direction, and the action protrusion 4 includes two action embedding parts 41 arranged symmetrically in the transverse direction, and the two action embedding parts 41 are connected to the two moving action parts 31 in a one-to-one correspondence. The two symmetrically arranged moving action parts 31 drive the two action embedding parts 41 to apply an action force to the pre-groove 210, so as to obtain two action forces of equal magnitude and opposite directions, so that the action force is closer to the net pressure in the crack, thereby achieving a better simulation effect.

[0061] In an exemplary embodiment of the present application, the pre-groove 210 is opened at the lower end of the rock layer located below and the opening faces downward. The center line of the pre-groove 210 coincides with the center line of the test sample 200 extending in the up and down directions. The inner contour of the pre-groove 210 is a rectangle. The outer contour of the action protrusion 4 is the same as the inner contour and is also a rectangle. The action protrusion 4 is inserted into the pre-groove 210 from bottom to top; the two action embedded parts 41 are symmetrically arranged with the center line of the pre-groove 210 as the symmetry axis. The movable action part 31 located on the left side is used to make the action embedded part 41 located on the left side have a tendency to move to the left so as to apply a leftward action force to the left side surface of the pre-groove 210, and the movable action part 31 located on the right side is used to make the action embedded part 41 located on the right side have a tendency to move to the right so as to apply a rightward action force to the right side surface of the pre-groove 210.

[0062] In fact, a guide groove 220 is provided on the upper side of the pre-groove 210, and the guide groove 220 shrinks inward from bottom to top to approach the center line of the test sample 200 extending in the vertical direction, so that the crack can be cracked in the vertical direction to meet the actual working conditions, thereby improving the reliability of the multi-thin interlayer interlayer fracturing crack extension visualization simulation device 100. For example, a guide groove 220 with a funnel-shaped inner contour is provided above the pre-groove 210 with a rectangular inner contour, and the lower bottom side of the funnel is wider than the upper bottom side, and the lower bottom side of the funnel overlaps with the upper side of the rectangle and has the same width.

[0063] like Figure 7As shown, in some embodiments, the visual simulation device 100 for fracture extension by multi-thin interlayer cross-layer fracturing further includes a shell 5, wherein a test sample 200 mounting cavity, a confining pressure component mounting cavity, and a moving component 3 mounting cavity are formed in the shell 5, wherein the confining pressure component mounting cavity and the moving component 3 mounting cavity are both connected to the test sample 200 mounting cavity, and the confining pressure component and the fracture pressure component are assembled into one by setting the shell 5. Before starting the experiment, it is only necessary to place the test sample 200 in the test sample 200 mounting cavity, thereby greatly improving the convenience and integrity of the visual simulation device 100 for fracture extension by multi-thin interlayer cross-layer fracturing.

[0064] Specifically, the housing 5 is in the shape of a cube. The front side of the housing 5 is provided with an installation opening which is connected with the installation cavity of the test sample 200 so as to place the test sample 200 therein. The multi-thin interlayer interlayer fracturing crack extension visualization simulation device 100 further includes a cover plate 51 for covering the installation opening; the installation cavity of the moving member 3 is connected with the installation cavity of the test sample 200 in the up-down direction, and two moving action parts 31 are installed in the installation cavity of the moving member 3 and can move in the left-right direction in the installation cavity of the moving member 3; the action embedding part 41 is arranged on the upper side of the moving action part 31 and extends upward into the installation cavity of the test sample 200.

[0065] Further, the lower side of the moving part 31 is provided with a limiting part 33 extending downward, and a limiting protrusion 52 extending upward is formed on the lower cavity wall of the installation cavity of the moving part 3. The limiting protrusion 52 is located on the outer side of the limiting part 33 along the left-right direction and forms a limiting groove 53 together with the limiting part 33 and the moving part 31. The lower side of the moving part 31 is the bottom wall of the limiting groove 53, and the side facing each other of the limiting part 33 and the moving part 31 is the groove wall of the limiting groove 53, and the opening of the limiting groove 53 faces downward. The crack pressure assembly also includes a limiting member 7, which can be limitedly matched with the limiting groove 53. Correspondingly, the lower side of the housing 5 is provided with an insertion port connected to the limiting groove 53, and the limiting member 7 is inserted into the limiting groove 53 from the insertion port.

[0066] When installing the test sample 200 into the test sample 200 installation cavity, it is necessary to ensure that the pre-groove 210 and the action protrusion 4 are aligned in the front-to-back direction so that the test sample 200 can be smoothly installed in the test sample 200 installation cavity. In other words, the two action embedded parts 41 cannot be separated, that is, the two movable action parts 31 are located in the initial position. By setting a limiting groove 53 and inserting a limiting member 7, the movable action part 31 is limited in the left-right direction, thereby facilitating the installation of the test sample 200.

[0067] Preferably, the limit members 7 on the left and right sides are integrally made U-shaped limiters, and the two legs of the U-shaped limiter are respectively limited and cooperated with the limit grooves 53 on the left and right sides, so as to realize the simultaneous insertion and removal of the limit members 7 on the left and right sides, thereby improving the convenience of the multi-thin interlayer through-layer fracturing crack expansion visualization simulation device 100.

[0068] Preferably, the cover plate 51 is a transparent acrylic member, through which the extension of the crack can be directly observed, thereby facilitating recording of the extension of the crack.

[0069] In an exemplary embodiment of the present application, the confining pressure driving part 21 is a hydraulic cylinder, the confining pressure acting part 22 is a flat jack, the piston of the hydraulic cylinder and the flat jack are installed in the confining pressure component mounting cavity, the left side, right side and upper side of the shell 5 are all provided with oil passages, the oil passages are connected with the corresponding confining pressure component mounting cavities, the oil delivery pipeline of the oil pump of the hydraulic cylinder passes through the oil passages and is connected with the piston, so as to accurately simulate the confining pressure through the hydraulic cylinder and the flat jack.

[0070] like Figure 8 and Fig.10 As shown, in some embodiments, a driving action part 32 is provided at the end of the movable action part 31 along the left-right direction, and the fracture pressure assembly also includes a driving member 6, which is used to apply an outward force along the left-right direction to the driving action part 32, and the net pressure in the fracture is simulated by mechanical loading through the driving member 6, the movable action part 31 and the action embedding part 41. Since the value of the mechanically loaded force is controllable, the value of the net pressure in the fracture can also be accurately simulated, thereby improving the reliability of the results of the through-layer fracturing experiment, and the structure of the mechanical loading is relatively simple and the cost is low, so that the production of the multi-thin interlayer through-layer fracturing fracture expansion visualization simulation device 100 is simpler and the cost is lower.

[0071] Specifically, the driving action portion 32 extends downward and is located on the outside of the limiting protrusion 52 along the left-right direction. A driving groove 54 is formed between the driving action portion 32 and the limiting protrusion 52. At least one inner side surface of the driving groove 54 is an inclined surface. The driving member 6 includes a wedge-shaped portion embedded in the driving groove 54 and a pushing portion for applying a force to the wedge-shaped portion along the up and down directions. The inclined surface of the wedge-shaped portion is fitted with the inclined surface of the driving groove 54. By controlling the force applied by the pushing portion to the wedge-shaped portion and analyzing the force on the wedge-shaped portion, an accurate net pressure in the crack can be directly obtained, thereby achieving an accurate simulation of the net pressure in the crack.

[0072] Furthermore, the pushing portion is a screw inserted into the wedge-shaped portion from bottom to top, and a plug-in port 55 corresponding to the screw is provided on the lower side of the shell 5. A torque screwdriver is inserted into the plug-in port 55 to apply a fixed torque force to the screw to achieve quantitative loading of the pre-groove 210, thereby achieving accurate simulation of the net pressure in the crack.

[0073] However, since the mechanical loading method requires a loading process, if the force applied by the driving member 6 to the movable action part 31 during the loading process drives the action embedding part 41 to act in the pre-groove 210, it may cause the pre-groove 210 to crack prematurely, which will affect the experimental results. Therefore, during the loading process, the limiting member 7 is used to limit the movable action part 31 to balance the force applied by the driving member 6 to the movable action part 31, so that after the limiting member 7 is withdrawn from the limiting groove 53, the force applied by the driving member 6 to the movable action part 31 will drive the action embedding part 41 to act in the pre-groove 210, thereby improving the reliability of the multi-thin interlayer through-layer fracturing crack expansion visualization simulation device 100.

[0074] Those skilled in the art will appreciate that, in addition to the above-mentioned screws for quantitative loading, a loading mechanism such as a hydraulic pump that can directly obtain the force may also be used.

[0075] In the exemplary embodiment of the present application, taking the moving action part 31 located on the left side as an example, the left end of the moving action part 31 is provided with a driving action part 32, the right side surface of the driving action part 32 is an inclined surface, and the angle between the right side surface of the driving action part 32 and the lower side surface of the moving action part 31 is an obtuse angle, and the left side surface of the driving member 6 is parallel to and fits with the right side surface of the driving action part 32; a limiting action part 33 is provided on the lower side surface of the moving action part 31, and the lower sides of the driving action part 32 and the limiting action part 33 are both in contact with the lower cavity wall of the installation cavity of the moving member 3; a limiting action part 33 is formed on the lower cavity wall of the installation cavity of the moving member 3 The limiting protrusion 52 is located between the driving action part 32 and the limiting action part 33, and the upper side of the limiting protrusion 52 abuts against the lower side of the moving action part 31; the left side of the limiting protrusion 52, the right side of the driving action part 32 and the upper cavity wall of the installation cavity of the moving member 3 jointly form a driving groove 54 whose inner contour is a right triangle, and the outer contour of the wedge-shaped part is a right-angled trapezoid, the two right-angled sides of the right-angled trapezoid overlap with the two right-angled sides of the right triangle respectively, the hypotenuse of the right-angled trapezoid overlaps with the hypotenuse of the right triangle, and there is a gap between the upper base of the right trapezoid and the upper vertex of the right triangle. The moving action part 31, the driving action part 32, the limiting action part 33, the limiting protrusion 52 and the driving member 6 on the right side are symmetrically arranged with the left side.

[0076] like Fig.11As shown, the specific embodiment of the present application also provides a through-layer fracturing experiment simulation system, including a test sample 200, a multi-thin interlayer through-layer fracturing crack extension visualization simulation device 100 and a recording device. Since the through-layer fracturing experiment simulation system adopts all embodiments of the multi-thin interlayer through-layer fracturing crack extension visualization simulation device 100, the through-layer fracturing experiment simulation system has all the beneficial effects brought by the multi-thin interlayer through-layer fracturing crack extension visualization simulation device 100.

[0077] As shown in the figure, the specific embodiment of the present application also provides a through-layer fracturing experiment simulation method implemented by the above-mentioned through-layer fracturing experiment simulation system:

[0078] S1: preparing a test sample 200 and providing a pre-groove 210 and a guide groove 220 on the test sample 200;

[0079] S2: restore the moving action part 31 to the initial position and insert the limiting member 7 into the limiting groove 53;

[0080] S3: Align the pre-grooved 210 with the active protrusion 4 to install the test sample 200 into the test sample 200 installation cavity;

[0081] S4: Cover the cover plate 51 on the installation opening and fix it;

[0082] S5: Apply confining pressure to the test sample 200 using the side confining pressure member 2 and the top confining pressure member 1;

[0083] S6: Using the driving member 6 to apply a force to the moving action part 31;

[0084] S7: After the stress and confining pressure are stable, set up the recording equipment and align it with the test sample 200;

[0085] S8: Pull the limiting member 7 out of the limiting groove 53 to start the through-layer fracturing experiment.

[0086] In step S1, the lithology of the test sample 200 and the interface inclination of the adjacent rock layers are the same as the on-site formation conditions. The size of the test sample 200 is determined according to the size of the installation cavity of the test sample 200, and the size of the pre-groove 210 is determined according to the size of the active protrusion 4.

[0087] In step S5, the confining pressure of each rock layer is the same as the on-site formation conditions, and different side confining pressure members 2 are used to adjust the confining pressure of the corresponding rock layer to accurately simulate the ground stress difference between the rock layers.

[0088] In step S6, the corresponding relationship between the force applied by the driver 6 to the moving action part 31 and the net pressure in the crack can be obtained according to the force analysis, so as to accurately simulate the size of the net pressure in the crack. Since the use of the driver 6 for loading requires a loading process, if the force applied by the driver 6 to the moving action part 31 during the loading process drives the action embedding part 41 to act in the pre-groove 210, it may cause the pre-groove 210 to crack in advance, which will affect the experimental results. Therefore, the limiter 7 is used to limit the moving action part 31 to balance the force applied by the driver 6 to the moving action part 31. Only when the limiter 7 is withdrawn from the limit groove 53, the force applied by the driver 6 to the moving action part 31 will drive the action embedding part 41 to act in the pre-groove 210.

[0089] In the present application, a simulation experiment is carried out using a test sample 200 that matches the on-site formation conditions. Multiple side confining pressure members 2 are used to apply side confining pressures to different rock formations to simulate ground stress conditions. Mechanical loading is used to quantitatively simulate the net pressure in the cracks, thereby achieving quantification, parameterization and refinement of the simulated through-layer fracturing experiment, thereby providing accurate basis and guidance for the design of through-layer fracturing technology, numerical simulation, etc.

[0090] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0091] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0093] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A visual simulation device for fracture propagation of multiple thin interlayers, characterized in that: The test sample (200) comprises a plurality of rock layers stacked in a longitudinal direction and extending in a transverse direction, a pre-groove (210) is formed on the rock layer at the bottom layer, and the multi-thin interlayer cross-layer fracturing crack extension visualization simulation device (100) comprises: a confining pressure assembly, used for applying confining pressure to the test sample (200) and comprising a plurality of side confining pressure members (2) arranged at intervals along the longitudinal direction, wherein the side confining pressure members (2) are arranged in one-to-one correspondence with the rock formations; and A crack pressure component is plugged into and matched with the pre-groove (210) and is used to apply an outward force to the groove wall of the pre-groove (210).

2. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 1 is characterized in that: The side pressure piece (2) comprises: A confining pressure driving unit (21) for providing a driving force in the lateral direction; The confining pressure acting part (22) is drivingly connected to the confining pressure driving part (21), and the confining pressure acting part (22) extends in the longitudinal direction, and the longitudinal length of the confining pressure acting part (22) is consistent with the longitudinal height of the corresponding rock formation.

3. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 1 is characterized in that: The confining pressure assembly further comprises a top confining pressure member (1) arranged on the rock layer at the topmost layer, and the action direction of the top confining pressure member (1) is perpendicular to the action direction of the side confining pressure member (2).

4. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 1, characterized in that: The crack pressure assembly comprises a moving part (3) and an action protrusion (4); the action protrusion (4) is plug-fitted with the pre-groove (210); and the moving part (3) is used to drive the action protrusion (4) to apply an action force to the pre-groove (210).

5. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 4 is characterized in that: The outer contour of the functional protrusion (4) is consistent with the inner contour of the pre-groove (210).

6. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 4, characterized in that: The moving member (3) comprises two moving action parts (31) symmetrically arranged along the transverse direction, and the two moving action parts (31) can move away from each other along the transverse direction. The action protrusion (4) comprises two action embedding parts (41) symmetrically arranged along the transverse direction, and the two action embedding parts (41) are connected to the two moving action parts (31) in a one-to-one correspondence.

7. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 6 is characterized in that: The multi-thin interlayer interlayer fracture extension visualization simulation device (100) further comprises a shell (5), wherein a test sample (200) installation cavity and a moving part (3) installation cavity connected to the test sample (200) installation cavity along the longitudinal direction are formed in the shell (5), and the two moving action parts (31) are capable of moving in the transverse direction in the moving part (3) installation cavity.

8. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 7, characterized in that: The action embedding portion (41) is arranged on one side of the movable action portion (31) along the longitudinal direction, and the movable action portion (31) is provided with a limiting action portion (33) on the other side of the longitudinal direction. A limiting protrusion (52) is formed on the cavity wall of the movable member (3) installation cavity along the longitudinal direction toward the movable action portion (31), and the limiting protrusion (52) is located on the outer side of the limiting action portion (33) along the transverse direction and forms a limiting groove (53) together with the limiting action portion (33) and the movable action portion (31). The crack pressure assembly also includes a limiting member (7), and the limiting member (7) can cooperate with the limiting groove (53) in a limiting manner.

9. The visual simulation device for multi-thin interlayer cross-layer fracturing crack extension according to claim 8, characterized in that: The moving action part (31) is provided with a driving action part (32) at the end along the lateral direction, and the crack pressure assembly further comprises a driving member (6), and the driving member (6) is used to apply an outward force along the lateral direction to the driving action part (32).

10. The visual simulation device for crack propagation of multiple thin interlayers through-layer fracturing according to claim 9, characterized in that: A driving groove (54) is formed between the driving action portion (32) and the limiting protrusion (52), at least one inner side surface of the driving groove (54) is an inclined surface, and the driving member (6) comprises a wedge-shaped portion embedded in the driving groove (54) and a pushing portion for applying a longitudinal force to the wedge-shaped portion, and the inclined surface of the wedge-shaped portion is in contact with the inclined surface of the driving groove (54).

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