Rock core clamping device

Abstract

The utility model provides a rock core clamping device, and belongs to the technical field of oil-gas field development. The rock core clamping device comprises a barrel, a protective sleeve used for being arranged on the outer side of a rock core in a sleeving mode is arranged in the barrel, a confining pressure through hole used for introducing a pressure medium into the periphery of the protective sleeve is formed in the barrel, plugs are arranged at the two ends of the protective sleeve, and at least part of each plug extends into the barrel and is in sealing fit with the inner wall of the barrel. One of the two plugs is a fixed plug with a fixed position, the other plug is a movable plug capable of moving, or the two plugs are both movable plugs, and the movable plug is provided with a force application mechanism which is used for applying force to the movable plug so as to apply pressure to the axial end face of the protective sleeve. At least one of the plugs at the two ends of the protective sleeve is arranged to be the movable plug, so that the protective sleeve is continuously subjected to radial pressure and axial pressure from a pressure medium, the real pressure condition of a stratum is simulated, and the accuracy of an experimental result is further improved.

Description

Technical Field

[0001] The utility model relates to a core clamping device and belongs to the technical field of oil and gas field development. Background Art

[0002] In the development process of carbonate oil and gas reservoirs, fracturing and acidizing is one of the important means to transform carbonate oil reservoirs and improve reservoir productivity. During the acid fracturing construction process, acid is injected into the crack wall for acid etching, thereby forming a support joint with conductivity to improve the crude oil seepage capacity and oil well production. The size of the fracture conductivity is directly related to the effect of acid fracturing construction. Therefore, it is of great significance to carry out indoor acid-etched fracture conductivity evaluation and analyze the influence of different factors on the conductivity of acid-etched fractures to improve the transformation effect of acid fracturing construction.

[0003] At present, a Chinese invention patent with authorization announcement number CN110412247B discloses a core clamping device and a core acid etching conductivity test device, wherein the core clamping device includes a cylinder body, on which a first pressurizing port is arranged; a clamp is detachably installed in the cylinder body, and an inner cylinder body of the clamp has a second pressurizing port connected to the first pressurizing port (that is, the first pressurizing port and the first pressurizing port constitute a confining pressure through hole); the clamp includes a protective sleeve and a plug that presses against the protective sleeve, and the pressure medium can enter between the cylinder wall of the inner cylinder body of the clamp and the protective sleeve through the first pressurizing port and the second pressurizing port to apply confining pressure to the protective sleeve, thereby causing the core wrapped by the protective sleeve to be subjected to pressure.

[0004] The plug at one end of the core clamping device is engaged with the inner cylinder through a step surface stop, and the plug at the other end is connected to the inner cylinder through a thread; however, since the protective sleeve is made of rubber and has the ability to deform, when the pressure medium is introduced into the space between the inner cylinder and the protective sleeve through the confining pressure through hole, the side of the protective sleeve is compressed and axially stretched, so that a top pressure is formed between the end of the protective sleeve and the inner end of the plug. However, this pressure is only the pressure generated by the elastic deformation of the protective sleeve, and cannot represent the actual pressure that the core is axially borne in the formation. That is, the device can only simulate the formation pressure that the core is circumferentially borne, and cannot simulate the actual pressure condition of the formation, thereby affecting the accuracy of the experimental results. Utility Model Content

[0005] The utility model aims to provide a core clamping device to solve the problem that the existing core clamping device can only simulate the formation pressure borne by the core in the circumferential direction but cannot simulate the real pressure condition of the formation, thereby affecting the accuracy of the experimental results.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A core clamping device comprises a cylinder body, in which a protective sleeve for being sleeved on the outside of the core is arranged, a confining pressure through hole for introducing a pressure medium to the outer periphery of the protective sleeve is opened on the cylinder body, plugs are arranged at both ends of the protective sleeve, at least part of the plugs extends into the cylinder body and is sealed with the inner wall of the cylinder body; one of the two plugs is a fixed plug with a fixed position, and the other is a movable plug that can be moved, or both plugs are movable plugs, and the movable plugs are provided with a force-applying mechanism for applying force to the movable plug and thereby applying pressure to the axial end face of the protective sleeve.

[0008] The beneficial effect of the above technical solution is that: the utility model improves the existing technology, at least one of the plugs at both ends of the protective sleeve is set as a movable plug, and a force-applying mechanism is arranged on the movable plug to apply axial pressure toward the core to the movable plug, so that the protective sleeve is continuously subjected to radial pressure and axial pressure from the pressure medium, simulating the actual pressure condition of the formation, thereby improving the accuracy of the experimental results.

[0009] Furthermore, the force-applying mechanism includes a power source having an inner cavity and a telescopic output end. The inner cavity is connected to the confining pressure through hole through an air inlet channel, so that the pressure medium enters the inner cavity through the air inlet channel and controls the movement of the telescopic output end. The telescopic output end cooperates with the movable plug in transmission.

[0010] The beneficial effect of the above technical solution is that the power source of the force-applying mechanism is connected to the confining pressure through hole through the air inlet channel, so that when the protective sleeve used to wrap the core is subjected to confining pressure, the force-applying mechanism configured on the movable plug applies axial pressure toward the core to the movable plug, thereby avoiding the need to configure an independent power mechanism for the power source and improving the linkage performance of the device.

[0011] Furthermore, the telescopic output end drives the movable plug to move through a connecting rod structure.

[0012] The beneficial effect of the above technical solution is that the connecting rod mechanism is easy to process and has a simple shape.

[0013] Furthermore, the connecting rod mechanism has at least two groups, and the connecting rod structure includes a fixed block, a sliding block, a clamping plate, a first connecting rod hinged between the fixed block and the clamping plate, and a second connecting rod hinged between the sliding block and the clamping plate. The clamping plate is used to clamp the movable plug, and the telescopic output end is connected to the sliding block.

[0014] The beneficial effect of the above technical solution is that the clamping plate applies an axial force toward the protective sleeve to the plug while clamping the plug, thereby increasing the stability of the plug installation.

[0015] Furthermore, the first connecting rod and the second connecting rod are hinged to the clamping plate via the same hinge axis.

[0016] The beneficial effects of the above technical solution are: facilitating the processing and manufacturing of the clamping plate and making the axial force on the plug more concentrated.

[0017] Furthermore, the cylinder includes a mounting portion located at an end portion, and the power source, the sliding block, and the fixed block are all mounted on the mounting portion.

[0018] The beneficial effects of the above technical solution are: the force source, sliding block and fixed block are all installed on the cylinder, which improves the installation stability of the force source, sliding block and fixed block; at the same time, compared with the use of a mounting frame to install the force source, sliding block and fixed block, the compactness of the device is improved.

[0019] Furthermore, the air inlet passage is arranged in the cylinder wall of the cylinder.

[0020] The beneficial effect of the above technical solution is that the air inlet channel pipe connecting the power source and the confining pressure through hole is arranged inside the cylinder wall, which has a compact structure and is safe and reliable.

[0021] Furthermore, the cylinder body is a stepped cylindrical structure that is thin in the middle and thick at both ends, so that the cylinder body has a small diameter section corresponding to the protective sleeve, and large diameter sections located at both ends of the cylinder body, and the large diameter sections constitute the installation portion; the outer end of the large diameter section is provided with a flange for installing the power source.

[0022] The beneficial effect of the above technical solution is that the power source, the sliding block and the fixed block are arranged between the outer side surface of the plug and the inner wall of the large diameter section of the cylinder, so that the core clamping device is easy to load and unload.

[0023] Furthermore, a guide rail is provided on the mounting portion, and the sliding block is in guiding sliding cooperation with the guide rail.

[0024] The beneficial effect of the above technical solution is that the guide rail structure is used to make the sliding block slide, the structure is simple, and the sliding block slides stably without deviation.

[0025] Furthermore, the power source is an inflatable bellows.

[0026] The beneficial effects of the above technical solution are: using the inflatable bellows as a power source, the structure is simple, and the inflatable bellows has good telescopic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of Example 1 of the core clamping device in the utility model.

[0028] In the figure: 1, cylinder; 101, confining pressure through hole; 102, flange; 103, air inlet channel; 2, protective cover; 3, core; 4, plug; 5, inflatable telescopic tube; 6, connecting rod mechanism; 601, fixed block; 602, sliding block; 603, clamping plate; 604, first connecting rod; 605, second connecting rod; 606, T-shaped guide rail; 7, guide piece; 701, guide hole. DETAILED DESCRIPTION

[0029] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0030] Specific embodiment 1 of the core clamping device provided by the utility model:

[0031] The main concept of this embodiment is that a protective sleeve for being sleeved on the outside of the core is provided in the cylinder, and a confining pressure through hole for introducing pressure medium to the outer periphery of the protective sleeve is opened on the cylinder. Plugs are provided at both ends of the protective sleeve, and a non-fixed connection is adopted between the plug and the inner wall of the cylinder. When the pressure medium is input, the plug can move in the direction away from the protective sleeve under the pushing action of the protective sleeve, thereby avoiding the formation of top pressure between the end of the protective sleeve and the inner end of the plug due to axial elongation of the protective sleeve. At the same time, a force-applying mechanism is arranged on the movable plug to apply axial pressure toward the core to the movable plug, so that the plug will not fall out of the cylinder and form a closed space between the plug and the inner wall of the cylinder, so that the protective sleeve is continuously subjected to radial pressure and axial pressure from the pressure medium, simulating the real pressure condition of the formation, thereby improving the accuracy of the experimental results.

[0032] Specific as Figure 1 As shown, the core clamping device is used to clamp the core 3 used for indoor acid-etched fracture conductivity evaluation. The core clamping device includes a cylinder 1, in which a protective sleeve 2 for sleeved on the outside of the core 3 is arranged. The protective sleeve 2 is composed of two semi-ring structures with a semicircular cross-section, which is convenient for replacing the core; a confining pressure through hole 101 for introducing a pressure medium into the outer periphery of the protective sleeve 2 is opened on the cylinder 1, and movable plugs 4 are arranged at both ends of the protective sleeve 2. The end of the plug 4 close to the protective sleeve 2 extends into the interior of the cylinder 1 and is sealed with the inner wall of the cylinder, so that the plug 4 and the inner wall of the cylinder 1 form a closed space. When conducting an experiment, the pressure medium is introduced into the closed space surrounded by the plug 4 and the inner wall of the cylinder 1 through the confining pressure through hole 101 to form a confining pressure on the protective sleeve 2 wrapping the core 3.

[0033] When the pressure medium is input, the plug 4 can move away from the protective sleeve 2 under the pushing action of the protective sleeve 2 and the pressure medium, avoiding the formation of top pressure between the end of the protective sleeve and the inner end of the plug due to the axial elongation of the protective sleeve, thereby affecting the real situation of the simulated formation. At the same time, a force-applying mechanism for applying force to the plug 4 and then to the axial end face of the protective sleeve 2 is configured on the plug 4.

[0034] The force-applying mechanism includes a power source, which in this embodiment is an inflatable telescopic tube 5, which has an inner cavity for inflating to achieve telescopic expansion, and the end surface of the inflatable telescopic tube 5 constitutes a telescopic output end. The confining pressure on the side of the cylinder 1 is a stepped cylindrical structure with a thin middle and thick ends, so that the cylinder 1 has a small diameter section corresponding to the protective sleeve 2, and a large diameter section located at both ends of the cylinder 1. The outer end of the large diameter section is provided with a flange 102 for installing the inflatable telescopic tube 5, and the cylinder wall of the cylinder 1 is provided with an air inlet channel 103 corresponding to the inflatable telescopic tube 5. One end of the air inlet channel 103 is connected to the inflatable telescopic tube 5, and the other end is connected to the confining pressure through hole 101. The area between the inner wall of the large diameter section and the outer side of the plug is used to install a connecting rod mechanism 6 that applies force to the plug 4.

[0035] The connecting rod mechanism 6 is provided with at least two groups. In this embodiment, the connecting rod mechanism is provided with four groups to realize the automatic centering of the clamped plug 4. The large diameter section of the cylinder 1 constitutes the mounting portion. The connecting rod mechanism 6 includes a fixed block 601 and a sliding block 602 mounted on the mounting portion. The mounting portion is provided with a T-shaped guide rail 606 along the axis direction of the cylinder 1. Correspondingly, a T-shaped groove is provided on the sliding block 602 to slide with the T-shaped guide rail 606. The sliding block 602 is connected to the end face of the inflatable telescopic tube 5. Driven by the inflatable telescopic tube 5, the sliding block 602 slides along the T-shaped guide rail 606.

[0036] The connecting rod mechanism 6 also includes a clamping plate 603 that fits with the outer peripheral surface of the plug 4 to clamp the plug 4. A first connecting rod 604 is hinged between the fixed block 601 and the clamping plate 603, and a second connecting rod 605 is hinged between the sliding block 602 and the clamping plate 603; the first connecting rod 604 and the second connecting rod 605 are hinged to the clamping plate 603 through the same hinge axis. When the sliding block 602 moves toward the core 3 driven by the inflatable telescopic tube 5, the clamping plate 603 is subjected to pressure in the axial and radial directions of the plug, so that the clamping plate 603 presses the outer side of the plug 4 while applying an axial force toward the core 3 to the plug 4. The axial force is finally balanced with the axial force of the pressure medium in the closed space surrounded by the plug 4 and the cylinder 1, so that the protective sleeve 2 is continuously subjected to radial pressure and axial pressure from the pressure medium, simulating the real pressure condition of the formation, thereby improving the accuracy of the experimental results.

[0037] During the experiment, it is necessary to input brine and acid into the core 3. In this embodiment, a guide member 7 is passed through the plug 4 along the axial direction, and the guide member 7 extends to the core 5 in the protective sleeve 2. The guide member 7 includes a guide hole 701 passing through the guide member 7, and a liquid inlet located at the end face of the guide member 7. The guide hole connects the end face of the core 5 and the liquid inlet. During the experiment, the acid and brine are transported from the liquid supply device to the core 5 in the protective sleeve 2 through the guide hole 701 passing through the guide member 7, and then the indoor acid-etched fracture conductivity evaluation is carried out.

[0038] The working principle of the core clamping device is as follows: when conducting an acid etching conductivity test on the core 3, after the core 3 is placed in the protective sleeve 2, a pressure medium is supplied to the confining pressure through hole 101, and the protective sleeve 2 is squeezed by the pressurized medium, thereby applying confining pressure to the core 3. At the same time, the pressure medium enters the inflatable telescopic tube 5 through the air inlet channel 103, and the pressure of the pressure medium is used to push the sliding block 602 toward the fixed block 601. The first connecting rod 604 and the second connecting rod 605 swing, driving the clamping plate 603 to clamp and fix the plug 4, and causing the plug 4 to be subjected to an axial force toward the core 3.

[0039] Salt water is introduced into the core 3 from the guide hole 701 of the guide member 7 at one end to simulate the formation water condition, and the conductivity of the core 3 before acid etching is recorded; then, acid is supplied to the core 3 from the guide hole 701 of the guide member 7 at the other end to allow the acid to etch the cracks; finally, salt water is introduced into the core 3 from the guide hole 701 of the guide member 7 through which the salt water was previously passed, and the salt water enters the core 3, and the conductivity of the core 3 after acid etching is recorded; after the experiment is completed, the supply of the pressure medium is stopped, the pressure in the inflatable telescopic tube 5 is reduced, the clamping force of the clamping plate 603 is reduced, and the core 3 to be tested is replaced.

[0040] Specific embodiment 2 of the core clamping device provided by the present invention: The structure of the power source provided in this embodiment is different from that of specific embodiment 1 in that the power source is a cylinder installed on the installation part.

[0041] Specific embodiment 3 of the core clamping device provided by the utility model: The sliding track of the sliding block in this embodiment is different from that of specific embodiment 1 in that a dovetail groove is provided on the sliding block, and a structure matching the dovetail groove is provided on the inner wall of the large diameter section of the cylinder. In other embodiments, a protrusion is provided on the sliding block to form a guide rail, and a groove is provided on the inner wall of the large diameter section of the cylinder accordingly.

[0042] Specific embodiment 4 of the core clamping device provided by the utility model: the structure of the cylinder provided in this embodiment is different from that of specific embodiment 1 in that the cylinder is not set in a stepped cylinder shape. At this time, a small diameter section is set at the outer end of the plug, and the connecting rod mechanism is set between the inner wall of the cylinder and the small diameter section of the plug.

[0043] Specific embodiment 5 of the core clamping device provided by the utility model: the pressure supply method of the inflatable telescopic part provided in this embodiment is different, and the difference from specific embodiment 1 is that no air inlet channel is arranged in the wall of the cylinder body. At this time, the pressure medium is supplied to the inflatable telescopic part through an external conduit, and the conduit constitutes the air inlet channel.

[0044] Specific embodiment 6 of the core clamping device provided by the present invention: The installation position of the connecting rod mechanism provided in this embodiment is different from that of specific embodiment 1 in that the connecting rod mechanism and the force-applying mechanism are not arranged on the cylinder body. At this time, the core clamping device is provided with a base frame for installing the connecting rod mechanism and the force-applying mechanism.

[0045] Specific embodiment 7 of the core clamping device provided by the present invention: the hinge structure of the first connecting rod and the second connecting rod provided in this embodiment is different from that of the specific embodiment 1 in that the first connecting rod and the second connecting rod are hinged to the clamping plate through different hinge axes.

[0046] Specific embodiment 8 of the core clamping device provided by the present invention: The number of connecting rod mechanisms provided in this embodiment is different from that in specific embodiment 1, the connecting rod mechanisms are arranged in 2 groups or 3 groups.

[0047] Specific embodiment 9 of the core clamping device provided by the utility model: In this embodiment, the power source applies force to the plug in a different manner, and the difference from specific embodiment 1 is that no connecting rod mechanism is provided between the telescopic output end and the plug. In this case, the end of the plug away from the core is provided as a small diameter section to form a step surface, and the telescopic output end of the power source presses against the step surface. In other embodiments, the telescopic output end of the power source directly presses against the outer end surface of the plug.

[0048] Specific embodiment 10 of the core clamping device provided by the utility model: the structure of the power source in this embodiment is different from that of specific embodiment 1 in that the power source is a hydraulic cylinder, a pneumatic cylinder or an electric push rod whose telescopic output end is pressed against the outer end surface of the plug.

[0049] Specific embodiment 11 of the core clamping device provided by the present invention: The structure of the plug in this embodiment is different from that of specific embodiment 1 in that one of the two plugs is a fixed plug with a fixed position, and the other is a movable plug that can move.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the description and drawings of the present invention shall be included in the protection scope of the present invention.

Claims

1. A core clamping device, comprising a cylinder, a protective sleeve for sleeved outside the core is arranged in the cylinder, a confining pressure through hole for introducing a pressure medium into the outer periphery of the protective sleeve is opened on the cylinder, plugs are arranged at both ends of the protective sleeve, at least part of the plugs extends into the cylinder and seals with the inner wall of the cylinder; characterized in that: One of the two plugs is a fixed plug with a fixed position, and the other is a movable plug, or both plugs are movable plugs, and the movable plugs are equipped with a force-applying mechanism for applying force to the movable plug and thus applying pressure to the axial end surface of the protective sleeve.

2. The core clamping device according to claim 1, characterized in that: The force-applying mechanism includes a power source having an inner cavity and a telescopic output end. The inner cavity is connected to the confining pressure through hole through an air inlet channel, so that the pressure medium enters the inner cavity through the air inlet channel and controls the movement of the telescopic output end. The telescopic output end cooperates with the movable plug in transmission.

3. The core clamping device according to claim 2, characterized in that: The telescopic output end drives the movable plug to move through the connecting rod structure.

4. The core clamping device according to claim 3, characterized in that: The connecting rod structure has at least two groups, and the connecting rod structure includes a fixed block, a sliding block, a clamping plate, a first connecting rod hinged between the fixed block and the clamping plate, and a second connecting rod hinged between the sliding block and the clamping plate. The clamping plate is used to clamp the movable plug, and the telescopic output end is connected to the sliding block.

5. The core clamping device according to claim 4, characterized in that: The first connecting rod and the second connecting rod are hinged to the clamping plate via the same hinge axis.

6. The core clamping device according to claim 4 or 5, characterized in that: The cylinder comprises a mounting portion located at an end portion, and a power source, a sliding block and a fixing block are all mounted on the mounting portion.

7. The core clamping device according to any one of claims 2 to 5, characterized in that: The air inlet passage is arranged in the cylinder wall of the cylinder.

8. The core clamping device according to claim 6, characterized in that: The cylinder body is in a stepped cylindrical structure with a thin middle and thick ends, so that the cylinder body has a small diameter section corresponding to the protective sleeve, and large diameter sections located at both ends of the cylinder body, and the large diameter sections constitute the installation part; the outer end of the large diameter section is provided with a flange for installing the power source.

9. The core clamping device according to claim 6, characterized in that: The installation portion is provided with a guide rail, and the sliding block is in guiding sliding cooperation with the guide rail.

10. The core clamping device according to any one of claims 2 to 5, characterized in that: The power source is an air-filled bellows.

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