Hydraulic fracturing experiment sample simulation shaft sealing device and method

Abstract

The invention discloses a hydraulic fracturing experiment sample simulation wellbore sealing device and method, and relates to the technical field of oil and gas reservoir hydraulic fracturing volume transformation development experiment research, the hydraulic fracturing experiment sample simulation wellbore sealing device comprises a rock sample, a rubber sealing mechanism is arranged above the rock sample, and a gas sealing mechanism is arranged above the rock sample; the rubber sealing mechanism comprises a rubber sealing unit, the rubber sealing unit is arranged above the rock sample, the rubber sealing unit can conduct rubber sealing on the shaft, the rubber sealing mechanism further comprises a limiting unit, the limiting unit is arranged above the rock sample, and the limiting unit is matched with the rubber sealing unit; according to the hydraulic fracturing experiment sample simulation shaft sealing device and method, by arranging the rubber sealing unit, the limiting unit and the air sealing mechanism, the problem that when equipment is used, the sealing effect is not good, and consequently water leakage occurs can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of experimental research on hydraulic fracturing volume transformation development of oil and gas reservoirs, and specifically to a simulation wellbore sealing device and method for hydraulic fracturing experimental specimens. Background Art

[0002] The experimental research project on hydraulic fracturing volume transformation development of oil and gas reservoirs is an effective means to study the volume transformation of oil and gas reservoirs at present. During hydraulic fracturing experiments, various specimens and wellbore sealing equipment will be used.

[0003] When the existing wellbore sealing equipment is in use, only epoxy resin is used as the sealant, the sealing form is single, and there will be a large number of air bubbles between the epoxy resin and the specimen wall surface, reducing the contact area between the epoxy resin and the specimen wall surface, resulting in a decrease in bearing capacity and easy liquid leakage problems during the experiment.

[0004] Combined with the above problems, it will be found that the existing simulation wellbore sealing devices for hydraulic fracturing experimental specimens on the market are difficult to avoid the above-mentioned problems simultaneously during use, and even if they can be solved, external tools need to be used for cooperation, thus unable to achieve the desired effect. Therefore, we propose a simulation wellbore sealing device and method for hydraulic fracturing experimental specimens. Summary of the Invention

[0005] The purpose of the present invention is to provide a simulation wellbore sealing device and method for hydraulic fracturing experimental specimens to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A simulation wellbore sealing device for hydraulic fracturing experimental specimens, including a rock specimen, with a rubber sealing mechanism arranged above the rock specimen and a gas sealing mechanism arranged above the rock specimen;

[0007] The rubber sealing mechanism includes a rubber sealing unit arranged above the rock specimen, and the rubber sealing unit can perform rubber sealing on the wellbore;

[0008] The rubber sealing mechanism further includes a limiting unit arranged above the rock specimen. The limiting unit cooperates with the rubber sealing unit, and the limiting unit can make the rubber sealing unit more stable inside the wellbore;

[0009] The gas sealing mechanism is arranged above the rock specimen. The gas sealing mechanism cooperates with the rubber sealing mechanism, and the gas sealing mechanism can perform gas sealing treatment on the wellbore.

[0010] Preferably, the rubber sealing unit includes a first opening gasket, a rolling bearing is fixedly connected to the outer surface of the first opening gasket, a second opening gasket is fixedly connected to the outer ring of the rolling bearing, a connecting plate is fixedly connected to the upper surface of the second opening gasket, a stud is fixedly connected to the upper surface of the connecting plate, a lifting block is threadedly connected to the outer surface of the stud, a circular shaft is slidably connected inside the stud, the connecting plate, the first opening gasket and the second opening gasket, a ring is threadedly connected to the outer surface of the circular shaft, a cone is fixedly connected to the bottom end of the circular shaft, and a rubber ring is arranged outside the circular shaft.

[0011] Preferably, a positioning shaft is fixedly connected to the upper surface of the first opening gasket, the inner part of the lifting block is slidably connected to the outer surface of the positioning shaft, the bottom surface of the first opening gasket is in contact with the upper surface of the rock sample, the outer surface of the first opening gasket is fixedly connected to the inner ring of the rolling bearing, the bottom end of the rubber ring is in contact with the outer surface of the cone, and both the rubber ring and the cone are arranged inside the cavity of the rock sample.

[0012] Preferably, the limiting unit includes a circular cylinder, two clamping plates are clamped inside the circular cylinder, two groups of compression blocks are slidably connected inside the circular cylinder, two sliding grooves are formed in the outer surface of the first opening gasket, a sliding shaft is slidably connected inside each sliding groove, a connecting ring is fixedly connected to the outer surfaces of the two sliding shafts together, a first extrusion block is fixedly connected to the outer surfaces of the two sliding shafts together, both the first extrusion block and the circular shaft are arranged inside the cavity of the circular cylinder, a second extrusion block is fixedly connected to the outer surface of the circular shaft, and the second extrusion block is arranged inside the cavity of the circular cylinder.

[0013] Preferably, two first fixing cylinders are fixedly connected to the inner wall of the first opening gasket, the two first fixing cylinders are symmetrically distributed with respect to the center of the circle of the circular cylinder, a first stress spring is fixedly connected to the inner wall of each first fixing cylinder, and a first clamping block is fixedly connected to one end of each first stress spring away from each other.

[0014] Preferably, two second fixing cylinders are fixedly connected to the inner wall of the circular cylinder, a second stress spring is fixedly connected to the inner wall of each second fixing cylinder, a second clamping block is fixedly connected to one end of the two second stress springs close to each other together, a rectangular plate is fixedly connected to the outer surface of each second clamping block, the outer surface of each rectangular plate is slidably connected inside the second fixing cylinder, and two clamping grooves are formed in the outer surface of the circular shaft.

[0015] Preferably, bull's-eye bearings are fixedly connected to one ends of the two second clamping blocks close to each other. The outer surfaces of each bull's-eye bearing are in contact with the outer surface of the circular shaft. The circular cylinder is arranged in the inner cavity of the rock sample. The upper surfaces of each clamping plate are fixedly connected to the bottom surface of the first opening gasket. The upper surface of the circular cylinder is in contact with the bottom surface of the first opening gasket. The number of each group of compression blocks is two, and the two groups of compression blocks are evenly distributed around the center of the circular cylinder.

[0016] Preferably, the airtight mechanism includes a limiting cylinder. A number of identical communication ports are formed in the outer surface of the limiting cylinder. A number of identical air delivery ports are formed in the outer surface of the circular shaft. An airbag is fixedly communicated with the outer surface of the limiting cylinder. A long shaft is slidably connected inside the circular shaft. A circular plate is fixedly connected to the bottom end of the long shaft. A first fixed rubber gasket is fixedly connected to the bottom surface of the circular plate. A first folding rubber gasket is fixedly connected to the outer surface of the first fixed rubber gasket. A first circular opening is formed in the upper surface of the circular plate. A second fixed rubber gasket is fixedly connected to the inner top wall of the circular shaft. A second folding rubber gasket is fixedly connected to the outer surface of the second fixed rubber gasket. A second circular opening is formed in the top end of the circular shaft.

[0017] Preferably, a rubber sealing plate is fixedly connected to the outer surface of the circular shaft. The outer surface of the rubber sealing plate is in contact with the inner wall of the limiting cylinder. The top end of the long shaft penetrates through the circular shaft and extends above the circular shaft. A force-bearing plate is fixedly connected to the top end of the long shaft. The top end of the limiting cylinder is in contact with the bottom end of the circular cylinder. The bottom end of the limiting cylinder is in contact with the top end of the rubber ring. The upper surface of the first folding rubber gasket is in contact with the bottom surface of the circular plate. The upper surface of the second folding rubber gasket is in contact with the inner top wall of the circular shaft.

[0018] A method for simulating a wellbore sealing device of a hydraulic fracturing experiment sample includes the following steps:

[0019] S1: Place the first opening gasket on the upper surface of the rock sample. Then, a rotating force can be applied to the second opening gasket to drive the second opening gasket and the connecting plate and the stud fixed above it to rotate. When the stud rotates, it will use the thread connection relationship to push the lifting block upward. As the second opening gasket continues to rotate, finally, the lifting block will be pushed to contact the bottom surface of the ring. Thus, the ring and the circular shaft can be pushed upward. When the circular shaft moves upward, it will drive the expansion cone to move upward synchronously. Therefore, the expansion cone will be extruded into the inside of the rubber ring, causing the rubber ring to expand and be in close contact with the inner wall of the rock sample to achieve the purpose of sealing.

[0020] S2: When the limiting unit needs to be used, the connecting ring can be pressed downward. When the connecting ring moves downward, it will drive the two sliding shafts to slide along the inside of the sliding groove, so as to push the first extrusion block fixed on the surface of the sliding shaft to slide in the direction of the pressure-receiving block. When the first extrusion block contacts the pressure-receiving block, the first extrusion block will push the pressure-receiving block to move towards the rock specimen. Finally, the surface of the pressure-receiving block will contact the inner wall of the rock specimen, so as to limit the circular cylinder and the first opening gasket.

[0021] S3: The force-bearing plate can be pulled upward. When the force-bearing plate moves upward, it will drive the long shaft and the circular plate fixed at the bottom end of the long shaft to move upward synchronously. Therefore, the air in the space above the circular plate will be squeezed into the space below the circular plate. When the circular plate moves upward to a position close to the top of the circular shaft, the force-bearing plate can be pushed to make the long shaft and the circular plate move downward, prompting the air to move downward until the air enters the inside of the airbag to inflate the airbag and achieve the purpose of inflatable sealing.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. By setting the rubber sealing unit, using the rubber ring and the expanding cone structure in the rubber sealing unit, when the expanding cone moves upward to push the rubber ring to expand, the inside of the wellbore can be sealed, thereby reducing the occurrence of leakage problems inside the wellbore.

[0024] 2. By setting the limiting unit, the limiting unit can not only temporarily fix the first opening gasket above the rock specimen, but also fix the circular shaft in the rock specimen for a long time, thereby increasing the stability of the circular shaft and the rubber sealing unit inside the rock specimen.

[0025] 3. By setting the air sealing mechanism, the air sealing mechanism can inflate the airbag, so that the surface of the airbag contacts the inner wall of the rock specimen to increase the sealing effect. By setting the rubber sealing unit, the limiting unit and the air sealing mechanism, it can effectively avoid the problem of water leakage caused by poor sealing effect when the equipment is in use. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the whole of the present invention;

[0027] Figure 2 is a schematic structural diagram of the expanding cone of the present invention;

[0028] Figure 3 is a schematic structural diagram of the long shaft of the present invention;

[0029] Figure 4 is a schematic structural diagram of the connecting plate of the present invention;

[0030] Figure 5Schematic diagram of the structure of the second folding rubber pad of the present invention;

[0031] Figure 6 Schematic diagram of the structure of the first folding rubber pad of the present invention;

[0032] Figure 7 Schematic diagram of the structure of the airbag of the present invention;

[0033] Figure 8 Schematic diagram of the structure of the first fixing cylinder of the present invention;

[0034] Figure 9 Schematic diagram of the structure of the first stress spring of the present invention;

[0035] Figure 10 Schematic diagram of the structure of the extrusion block of the present invention;

[0036] Figure 11 Left view structure diagram of the second fixing cylinder of the present invention;

[0037] Figure 12 Left view structure diagram of the second stress spring of the present invention;

[0038] Figure 13 Schematic diagram of the structure of the rubber ring of the present invention.

[0039] In the figure: 1. Rock sample; 2. Rubber sealing mechanism; 21. Rubber sealing unit; 2101. Circular shaft; 2102. Ring; 2103. Positioning shaft; 2104. Stud; 2105. Lifting block; 2106. Connecting plate; 2107. Second opening pad; 2108. First opening pad; 2109. Expansion cone; 2110. Rubber ring; 2111. Rolling bearing; 22. Limiting unit; 2201. Connecting ring; 2202. First clamping block; 2203. Circular cylinder; 2204. Compressed block; 2205. Card slot; 2206. Sliding slot; 2207. Sliding shaft; 2208. First extrusion block; 2209. Card plate; 2210. First fixing cylinder; 2211. First stress spring; 2212. Second extrusion block; 2213. Second fixing cylinder; 2214. Bull's-eye bearing; 2215. Rectangular plate; 2216. Second clamping block; 2217. Second stress spring; 3. Air sealing mechanism; 301. Stress plate; 302. Airbag; 303. Limiting cylinder; 304. Communication port; 305. Circular plate; 306. Long shaft; 307. Air inlet; 308. Second circular opening; 309. Second folding rubber pad; 310. Second fixed rubber pad; 311. First fixed rubber pad; 312. First folding rubber pad; 313. First circular opening; 314. Rubber sealing plate. Detailed implementation manners

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Embodiment 1: Please refer to Figures 1-4 , Figure 7 and Figure 8 , the present invention provides a technical solution: a simulation wellbore sealing device for a hydraulic fracturing experiment specimen. The present invention makes corresponding improvements to the technical problems mentioned in the background art, including a rock specimen 1, a rubber sealing mechanism 2 is arranged above the rock specimen 1, and a gas sealing mechanism 3 is arranged above the rock specimen 1;

[0042] The rubber sealing mechanism 2 includes a rubber sealing unit 21. The rubber sealing unit 21 is arranged above the rock specimen 1, and the rubber sealing unit 21 can perform rubber sealing on the wellbore.

[0043] As a further limitation of the rubber sealing mechanism 2 of the present invention, the rubber sealing unit 21 includes a first opening pad 2108. A rolling bearing 2111 is fixedly connected to the outer surface of the first opening pad 2108. The outer ring of the rolling bearing 2111 is fixedly connected to a second opening pad 2107. A connecting plate 2106 is fixedly connected to the upper surface of the second opening pad 2107. A stud 2104 is fixedly connected to the upper surface of the connecting plate 2106. A lifting block 2105 is threadedly connected to the outer surface of the stud 2104. A circular shaft 2101 is slidably connected inside the stud 2104, the connecting plate 2106, the first opening pad 2108 and the second opening pad 2107. A ring 2102 is threadedly connected to the outer surface of the circular shaft 2101. A swelling cone 2109 is fixedly connected to the bottom end of the circular shaft 2101. A rubber ring 2110 is arranged outside the circular shaft 2101. By setting the rubber sealing unit 21, using the rubber ring 2110 and the swelling cone 2109 structures in the rubber sealing unit 21, the swelling cone 2109 moves upward to push the rubber ring 2110 to expand, so as to seal the inside of the wellbore, thereby reducing the occurrence of leakage problems inside the wellbore.

[0044] Please refer to Figure 1 and Figure 2, a positioning shaft 2103 is fixedly connected to the upper surface of the first opening gasket 2108. The inner part of the lifting block 2105 is slidably connected to the outer surface of the positioning shaft 2103. The bottom surface of the first opening gasket 2108 is in contact with the upper surface of the rock specimen 1. The outer surface of the first opening gasket 2108 is fixedly connected to the inner ring of the rolling bearing 2111. The bottom end of the rubber ring 2110 is in contact with the outer surface of the expansion cone 2109. Both the rubber ring 2110 and the expansion cone 2109 are arranged in the inner cavity of the rock specimen 1. By providing the positioning shaft 2103, the moving position of the lifting block 2105 can be limited by the positioning shaft 2103, so that the lifting block 2105 can only move in the up and down directions.

[0045] The specific implementation manner of this embodiment is as follows: When the device needs to be used, place the first opening gasket 2108 on the upper surface of the rock specimen 1, and there is a layer of rubber covering the bottom surface of the first opening gasket 2108. The characteristic of large friction coefficient of the rubber can be used to increase the friction force between the first opening gasket 2108 and the rock specimen 1, and it is necessary to make the equipment below the first opening gasket 2108 be inside the rock specimen 1. Subsequently, use the limiting unit 22 to fix the whole equipment to the rock specimen 1, and then the second opening gasket 2107 can be applied with rotational power to drive the second opening gasket 2107 and the upper fixed connecting plate 2106 and stud 2104 to rotate. When the stud 2104 rotates, it will push the lifting block 2105 to move upward by using the thread connection relationship. Here, it should be understood that the lifting block 2105 slides on the surface of the positioning shaft 2103, so the lifting block 2105 can only move in the up and down directions. As the second opening gasket 2107 continues to rotate, finally, the lifting block 2105 will be pushed to contact the bottom surface of the ring 2102, and thus the ring 2102 and the circular shaft 2101 can be pushed upward. When the circular shaft 2101 moves upward, it will drive the expansion cone 2109 to move upward synchronously. Therefore, the expansion cone 2109 will be squeezed into the inside of the rubber ring 2110, so that the rubber ring 2110 expands and is in close contact with the inner wall of the rock specimen 1 to achieve the purpose of sealing. Here, it should be understood that the top end of the rubber ring 2110 is in contact with the bottom end of the limiting cylinder 303, and the top end of the limiting cylinder 303 is fixedly connected to the bottom end of the circular cylinder 2203, and the top end of the circular cylinder 2203 is in contact with the first opening gasket 2108. Therefore, when the expansion cone 2109 enters the inside of the rubber ring 2110, it will not push the rubber ring 2110 upward.

[0046] Example 2: Please refer to Figures 1-4 and Figures 8-13, the present invention provides a technical solution: a simulation wellbore sealing device for hydraulic fracturing experimental specimens. The present invention makes corresponding improvements to the technical problems mentioned in the background art. The rubber sealing mechanism 2 further includes a limiting unit 22. The limiting unit 22 is arranged above the rock specimen 1. The limiting unit 22 cooperates with the rubber sealing unit 21, and the limiting unit 22 can make the rubber sealing unit 21 more stable inside the wellbore.

[0047] As a further limitation of the rubber sealing mechanism 2 of the present invention, the limiting unit 22 includes a circular cylinder 2203. Two clamping plates 2209 are clamped inside the circular cylinder 2203. Two groups of compression blocks 2204 are slidably connected inside the circular cylinder 2203. Two sliding grooves 2206 are opened on the outer surface of the first opening gasket 2108. A sliding shaft 2207 is slidably connected inside each sliding groove 2206. A connecting ring 2201 is fixedly connected to the outer surfaces of the two sliding shafts 2207 together. A first extrusion block 2208 is fixedly connected to the outer surfaces of the two sliding shafts 2207 together. Both the first extrusion block 2208 and the circular shaft 2101 are arranged inside the inner cavity of the circular cylinder 2203. A second extrusion block 2212 is fixedly connected to the outer surface of the circular shaft 2101. The second extrusion block 2212 is arranged inside the inner cavity of the circular cylinder 2203. By setting the limiting unit 22, the limiting unit 22 can not only temporarily fix the first opening gasket 2108 above the rock specimen 1, but also fix the circular shaft 2101 inside the rock specimen 1 for a long time, thereby increasing the stability of the circular shaft 2101 and the rubber sealing unit 21 inside the rock specimen 1.

[0048] Please refer to Figure 9 , two first fixing cylinders 2210 are fixedly connected to the inner wall of the first opening gasket 2108. The two first fixing cylinders 2210 are symmetrically distributed with respect to the center of the circular cylinder 2203. A first stress spring 2211 is fixedly connected to the inner wall of each first fixing cylinder 2210. A first clamping block 2202 is fixedly connected to the end of each of the two first stress springs 2211 away from each other. By setting the first fixing cylinders 2210, the first stress springs 2211 and the first clamping blocks 2202, the first stress spring 2211 can be used to push the first clamping block 2202 to limit the connecting ring 2201.

[0049] Please refer to Figure 11 and Figure 12, two second fixed cylinders 2213 are fixedly connected to the inner wall of the circular cylinder 2203. A second force spring 2217 is fixedly connected to the inner wall of each second fixed cylinder 2213. The second force springs 2217 push against each other at their proximal ends, and a second latch 2216 is fixedly connected to the proximal ends of the second force springs 2217. A rectangular plate 2215 is fixedly connected to the outer surface of each second latch 2216. The outer surface of each rectangular plate 2215 is slidably connected to the inside of the second fixed cylinder 2213. Two card slots 2205 are formed on the outer surface of the circular shaft 2101. By providing the second force spring 2217 and the second latch 2216, the second latch 2216 can be pushed into the card slot 2205 to connect the circular shaft 2101 to the circular cylinder 2203.

[0050] Please refer to Figure 11 and Figure 12 , a bull's-eye bearing 2214 is fixedly connected to the proximal end of each second latch 2216. The outer surface of each bull's-eye bearing 2214 is in contact with the outer surface of the circular shaft 2101. The circular cylinder 2203 is disposed within the inner cavity of the rock specimen 1. The upper surface of each clamping plate 2209 is fixedly connected to the bottom surface of the first opening gasket 2108. The upper surface of the circular cylinder 2203 is in contact with the bottom surface of the first opening gasket 2108. Each set of compression blocks 2204 has a quantity of two, and the two sets of compression blocks 2204 are evenly distributed around the center of the circular cylinder 2203. By providing the bull's-eye bearing 2214, the frictional force generated when the circular shaft 2101 moves upward can be reduced by utilizing the sliding property of the bull's-eye bearing 2214.

[0051] The specific implementation manner of this embodiment is as follows: When the limiting unit 22 needs to be used, the triggering step of the limiting unit 22 needs to be in front of the rubber sealing unit 21. After the first opening pad 2108 contacts the upper surface of the rock specimen 1, the connecting ring 2201 can be pressed downward. When the connecting ring 2201 moves downward, it will drive the two sliding shafts 2207 to slide along the inside of the sliding groove 2206, so as to push the first extrusion block 2208 fixed on the surface of the sliding shaft 2207 to slide in the direction of the pressure receiving block 2204. When the first extrusion block 2208 contacts the pressure receiving block 2204, the first extrusion block 2208 will push the pressure receiving block 2204 to move towards the rock specimen 1. Finally, the surface of the pressure receiving block 2204 will contact the inner wall of the rock specimen 1, and a layer of rubber is also covered on the surface of the pressure receiving block 2204. The characteristic of the large friction coefficient of rubber can be used to increase the friction between the pressure receiving block 2204 and the rock specimen 1, so as to limit the circular cylinder 2203 and the first opening pad 2108, and indirectly fix the first opening pad 2108 above the rock specimen 1. When the connecting ring 2201 is pushed downward, the connecting ring 2201 will squeeze the first clamping block 2202 inside the first fixed cylinder 2210, so that the first clamping block 2202 is squeezed into the first fixed cylinder 2210. Therefore, the first force-bearing spring 2211 will contract. When the connecting ring 2201 moves to the notch in the first clamping block 2202, the first force-bearing spring 2211 will push the first clamping block 2202 to quickly reset, limit the connecting ring 2201, prevent the connecting ring 2201 from moving upward, and further prevent the sliding shaft 2207 and the first extrusion block 2208 from moving upward, so that the first extrusion block 2208 can stably provide pressure on the pressure receiving block 2204. When the user applies a rotational force to the second opening pad 2107, it is not necessary for the user to use the other hand to limit the first opening pad 2108. Then the user can apply a rotational force to the second opening pad 2107 to drive the circular shaft 2101 and the expansion cone 2109 in the rubber sealing unit 21 to move upward, prompting the rubber ring 2110 to expand, achieving the purpose of rubber sealing. And when the circular shaft 2101 moves upward, it will push the second extrusion block 2212 upward, so that the second extrusion block 2212 contacts the two pressure receiving blocks 2204. At this time, the second extrusion block 2212 can also provide pressure on the pressure receiving blocks 2204. When the circular shaft 2101 moves upward, the card slot 2205 opened on the surface of the circular shaft 2101 will move to the positions of the two bull's-eye bearings 2214. The bull's-eye bearings 2214 and the second clamping blocks 2216 will enter the inside of the card slot 2205 under the thrust of the second force-bearing spring 2217, so as to limit the circular shaft 2101 and connect the circular cylinder 2203 with the circular shaft 2101. It can be understood here that the bull's-eye bearings 2214 and the second clamping blocks 2216 are always under the elastic extrusion of the second force-bearing spring 2217. Therefore, the bull's-eye bearings 2214 always contact the surface of the circular shaft 2101.Subsequently, the circular ring 2102 can be unscrewed from the circular shaft 2101, and then the first opening gasket 2108 is pulled upward with force. The clamping plate 2209 fixed to the bottom surface of the first opening gasket 2108 will then be disengaged from the clamping connection with the circular cylinder 2203. At this time, the connecting ring 2201, the sliding shaft 2207, the first extrusion block 2208, the first opening gasket 2108, and the structure above the first opening gasket 2108 can be removed, and the circular shaft 2101, the circular cylinder 2203, the pressure-receiving block 2204, the second extrusion block 2212, the expansion cone 2109, the limiting cylinder 303, and the rubber ring 2110 will still remain inside the rock specimen 1, completing the limiting effect on the rubber sealing unit 21.

[0052] Embodiment 3: Please refer to Figures 1-8 , Figure 10 , Figure 11 and Figure 13 , the present invention provides a technical solution: a simulation wellbore sealing device for a hydraulic fracturing experiment specimen. The present invention makes corresponding improvements to the technical problems mentioned in the background art. The gas sealing mechanism 3 is arranged above the rock specimen 1, and the gas sealing mechanism 3 and the rubber sealing mechanism 2 cooperate with each other. The gas sealing mechanism 3 can perform gas sealing treatment on the wellbore.

[0053] As a further limitation of the gas sealing mechanism 3 of the present invention, the gas sealing mechanism 3 includes a limiting cylinder 303. A plurality of identical communication ports 304 are provided on the outer surface of the limiting cylinder 303. A plurality of identical gas transmission ports 307 are provided on the outer surface of the circular shaft 2101. An airbag 302 is fixedly connected to the outer surface of the limiting cylinder 303. A long shaft 306 is slidably connected inside the circular shaft 2101. A circular plate 305 is fixedly connected to the bottom end of the long shaft 306. A first fixed rubber pad 311 is fixedly connected to the bottom surface of the circular plate 305. A first folding rubber pad 312 is fixedly connected to the outer surface of the first fixed rubber pad 311. A first circular opening 313 is provided on the upper surface of the circular plate 305. A second fixed rubber pad 310 is fixedly connected to the inner top wall of the circular shaft 2101. A second folding rubber pad 309 is fixedly connected to the outer surface of the second fixed rubber pad 310. A second circular opening 308 is provided at the top end of the circular shaft 2101. By setting the gas sealing mechanism 3, the gas sealing mechanism 3 can be used to inflate the inside of the airbag 302, so that the surface of the airbag 302 contacts the inner wall of the rock specimen 1, increasing the sealing effect. By providing the rubber sealing unit 21, the limiting unit 22, and the gas sealing mechanism 3, it can effectively avoid the problem of water leakage caused by poor sealing effect when the equipment is in use.

[0054] Please refer to Figure 3 and Figure 13, a rubber sealing plate 314 is fixedly connected to the outer surface of the circular shaft 2101. The outer surface of the rubber sealing plate 314 is in contact with the inner wall of the limiting cylinder 303. The top end of the long shaft 306 penetrates through the circular shaft 2101 and extends above the circular shaft 2101. A force-bearing plate 301 is fixedly connected to the top end of the long shaft 306. The top end of the limiting cylinder 303 is in contact with the bottom end of the circular cylinder 2203. The bottom end of the limiting cylinder 303 is in contact with the top end of the rubber ring 2110. The upper surface of the first folding rubber pad 312 is in contact with the bottom surface of the circular plate 305. The upper surface of the second folding rubber pad 309 is in contact with the inner top wall of the circular shaft 2101. By providing the rubber sealing plate 314, the rubber sealing plate 314 can ensure that gas only enters the interior of the airbag 302. When the rubber sealing plate 314 moves downward to below the air outlet 307, it can guide the gas in the airbag 302 to flow out to the outside. In addition, the presence of the force-bearing plate 301 can facilitate applying power to the circular shaft 1 to drive the circular shaft 1 to move upward or downward.

[0055] The specific implementation of this embodiment is as follows: When the connecting ring 2201, sliding shaft 2207, first extrusion block 2208, first opening pad 2108 and the structure above the first opening pad 2108 are removed, the force-bearing plate 301 can be pulled upward. When the force-bearing plate 301 moves upward, it will drive the long shaft 306 and the circular plate 305 fixed at the bottom end of the long shaft 306 to move upward synchronously. Therefore, the air in the space above the circular plate 305 will be squeezed, increasing the pressure in the space above the circular plate 305. And the size of the second folding rubber pad 309 is larger than that of the second circular opening 308, so the air pressure will push the second folding rubber pad 309 to tightly adhere to the inner top wall of the circular shaft 2101. Instead, the first folding rubber pad 312 below the circular plate 305 will expand downward under the action of the air pressure. Therefore, the air in the space above the circular plate 305 will enter the space below the circular plate 305. When the circular plate 305 moves upward to a position close to the top of the circular shaft 2101, the force-bearing plate 301 can be pushed to make the long shaft 306 and the circular plate 305 move downward. During the downward movement, a large amount of air will be stored in the space below the circular plate 305. So the downward-moving air will squeeze the first folding rubber pad 312 below the circular plate 305 to closely adhere to the bottom surface of the circular plate 305, preventing the gas from flowing through the second circular opening 308 to the space above the circular plate 305, prompting the air to move downward until the air enters the inside of the airbag 302 to inflate the airbag 302, achieving the purpose of inflating and sealing. And when the circular plate 305 moves downward, the gas content in the space above the circular plate 305 is less, so a negative pressure state will be formed, which can pull the second folding rubber pad 310 to fold downward by suction. At this time, the outside air will enter the space above the circular plate 305. By repeating this process, the purpose of inflating the airbag 302 can be achieved. When it is necessary to remove the circular shaft 2101, circular cylinder 2203, compression block 2204, second extrusion block 2212, expansion cone 2109, limit cylinder 303 and rubber ring 2110 from the inside of the rock specimen 1, push the two rectangular plates 2215, so that the second clamping block 2216 and the bull's-eye bearing 2214 fixed on the surface of the rectangular plate 2215 squeeze the second force spring 2217, making the bull's-eye bearing 2214 stop the clamping relationship with the card slot 2205. Then press the circular shaft 2101 downward, which can drive the expansion cone 2109 and the rubber sealing plate 314 to move downward. The expansion cone 2109 will stop squeezing the rubber ring 2110, and the rubber sealing plate 314 will move below the communication port 304 opened on the surface of the limit cylinder 303. At this time, the gas inside the airbag 302 will be discharged outward through the communication port 304, making the airbag 302 no longer full. Then the device can be disassembled.

[0056] A method for simulating a wellbore sealing device for a hydraulic fracturing experiment specimen includes the following steps:

[0057] S1: Place the first opening pad 2108 on the upper surface of the rock specimen 1. Then, rotational power can be applied to the second opening pad 2107, driving the second opening pad 2107, the connecting plate 2106 and the stud 2104 fixed above to rotate. When the stud 2104 rotates, it will push the lifting block 2105 upward using the threaded connection relationship. As the second opening pad 2107 continues to rotate, it will eventually push the lifting block 2105 into contact with the bottom surface of the ring 2102, thereby pushing the ring 2102 and the circular shaft 2101 upward. When the circular shaft 2101 moves upward, it will drive the expansion cone 2109 to move upward synchronously. Therefore, the expansion cone 2109 will be squeezed into the interior of the rubber ring 2110, causing the rubber ring 2110 to expand and come into close contact with the inner wall of the rock specimen 1;

[0058] S2: When the limiting unit 22 needs to be used, the connecting ring 2201 can be pressed downward. When the connecting ring 2201 moves downward, it will drive the two sliding shafts 2207 to slide along the interior of the sliding groove 2206, thereby pushing the first extrusion block 2208 fixed on the surface of the sliding shaft 2207 to slide in the direction of the pressure-receiving block 2204. When the first extrusion block 2208 comes into contact with the pressure-receiving block 2204, the first extrusion block 2208 will push the pressure-receiving block 2204 toward the rock specimen 1. Eventually, the surface of the pressure-receiving block 2204 will come into contact with the inner wall of the rock specimen 1, thereby limiting the circular cylinder 2203 and the first opening pad 2108;

[0059] S3: The force-receiving plate 301 can be pulled upward. When the force-receiving plate 301 moves upward, it will drive the long shaft 306 and the circular plate 305 fixed at the bottom end of the long shaft 306 to move upward synchronously. Therefore, the air in the space above the circular plate 305 will be squeezed into the space below the circular plate 305. When the circular plate 305 moves upward to a position close to the top of the circular shaft 2101, the force-receiving plate 301 can be pushed to move the long shaft 306 and the circular plate 305 downward, prompting the air to move downward until it enters the interior of the airbag 302 to inflate the airbag 302.

[0060] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such process, method, article or device.

[0061] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydraulic fracturing test specimen simulating a wellbore sealing device, comprising a rock specimen (1), characterized in that: A rubber sealing mechanism (2) is provided above the rock sample (1), and an air sealing mechanism (3) is provided above the rock sample (1); The rubber sealing mechanism (2) comprises a rubber sealing unit (21), wherein the rubber sealing unit (21) is arranged above the rock sample (1), and the rubber sealing unit (21) can perform rubber sealing on the wellbore; The rubber sealing mechanism (2) further comprises a limiting unit (22), wherein the limiting unit (22) is arranged above the rock sample (1), and the limiting unit (22) cooperates with the rubber sealing unit (21), and the limiting unit (22) can make the rubber sealing unit (21) more stable inside the wellbore; The air sealing mechanism (3) is arranged above the rock sample (1); the air sealing mechanism (3) and the rubber sealing mechanism (2) cooperate with each other; the air sealing mechanism (3) can perform air-sealing treatment on the wellbore.

2. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 1, characterized in that: The rubber sealing unit (21) comprises a first open pad (2108), the outer surface of the first open pad (2108) is fixedly connected to a rolling bearing (2111), the outer ring of the rolling bearing (2111) is fixedly connected to a second open pad (2107), the upper surface of the second open pad (2107) is fixedly connected to a connecting plate (2106), the upper surface of the connecting plate (2106) is fixedly connected to a stud (2104), the outer surface of the stud (2104) is fixedly connected to the outer surface of the stud (2104). A lifting block (2105) is threadedly connected to the surface; a circular shaft (2101) is slidably connected to the inside of the stud (2104), the connecting plate (2106), the first opening pad (2108) and the second opening pad (2107); a circular ring (2102) is threadedly connected to the outer surface of the circular shaft (2101); an expansion cone (2109) is fixedly connected to the bottom end of the circular shaft (2101); and a rubber ring (2110) is arranged on the outside of the circular shaft (2101).

3. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 2, characterized in that: The upper surface of the first opening pad (2108) is fixedly connected to a positioning shaft (2103); the interior of the lifting block (2105) is slidably connected to the outer surface of the positioning shaft (2103); the bottom surface of the first opening pad (2108) is in contact with the upper surface of the rock sample (1); the outer surface of the first opening pad (2108) is fixedly connected to the inner ring of the rolling bearing (2111); the bottom end of the rubber ring (2110) is in contact with the outer surface of the expansion cone (2109); and the rubber ring (2110) and the expansion cone (2109) are both arranged in the inner cavity of the rock sample (1).

4. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 2, characterized in that: The limiting unit (22) comprises a circular cylinder (2203), the interior of which is clamped with two clamping plates (2209), the interior of which is slidably connected with two groups of pressure blocks (2204), the outer surface of the first opening pad (2108) is provided with two sliding grooves (2206), the interior of each sliding groove (2206) is slidably connected with a sliding shaft (2207), the outer surfaces of the two sliding shafts (2207) are fixedly connected with a connecting ring (2201), the outer surfaces of the two sliding shafts (2207) are fixedly connected with a first extrusion block (2208), the first extrusion block (2208) and the circular shaft (2101) are both arranged in the inner cavity of the circular cylinder (2203), the outer surface of the circular shaft (2101) is fixedly connected with a second extrusion block (2212), and the second extrusion block (2212) is arranged in the inner cavity of the circular cylinder (2203).

5. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 4, characterized in that: The inner wall of the first opening pad (2108) is fixedly connected to two first fixed cylinders (2210), and the two first fixed cylinders (2210) are symmetrically distributed around the center of the circular cylinder (2203). The inner wall of each first fixed cylinder (2210) is fixedly connected to a first force spring (2211), and the ends of the two first force springs (2211) that are away from each other are fixedly connected to a first clamping block (2202).

6. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 4, characterized in that: The inner wall of the circular cylinder (2203) is fixedly connected to two second fixed cylinders (2213), the inner wall of each of the second fixed cylinders (2213) is fixedly connected to a second force-bearing spring (2217), the two second force-bearing springs (2217) are fixedly connected to a second clamping block (2216) at one end close to each other, the outer surface of each of the second clamping blocks (2216) is fixedly connected to a rectangular plate (2215), the outer surface of each of the rectangular plates (2215) is slidably connected to the inside of the second fixed cylinder (2213), and the outer surface of the circular shaft (2101) is provided with two clamping grooves (2205).

7. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 6, characterized in that: The ends of the two second clamping blocks (2216) that are close to each other are fixedly connected with a bull's eye bearing (2214), and the outer surface of each bull's eye bearing (2214) is in contact with the outer surface of the circular shaft (2101). The circular cylinder (2203) is arranged in the inner cavity of the rock sample (1), and the upper surface of each clamping plate (2209) is fixedly connected to the bottom surface of the first opening pad (2108), and the upper surface of the circular cylinder (2203) is in contact with the bottom surface of the first opening pad (2108). The number of each group of pressure blocks (2204) is two, and the two groups of pressure blocks (2204) are evenly distributed around the center of the circular cylinder (2203).

8. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 4, characterized in that: The air sealing mechanism (3) comprises a limiting cylinder (303), the outer surface of the limiting cylinder (303) is provided with a plurality of identical communication ports (304), the outer surface of the circular shaft (2101) is provided with a plurality of identical air delivery ports (307), the outer surface of the limiting cylinder (303) is fixedly connected to an air bag (302), the interior of the circular shaft (2101) is slidably connected to a long shaft (306), the bottom end of the long shaft (306) is fixedly connected to a circular plate (305), and the bottom surface of the circular plate (305) is A first fixed rubber pad (311) is fixedly connected, and a first folding rubber pad (312) is fixedly connected to the outer surface of the first fixed rubber pad (311); a first circular opening (313) is provided on the upper surface of the circular plate (305); a second fixed rubber pad (310) is fixedly connected to the inner top wall of the circular shaft (2101); a second folding rubber pad (309) is fixedly connected to the outer surface of the second fixed rubber pad (310); and a second circular opening (308) is provided at the top end of the circular shaft (2101).

9. A hydraulic fracturing test specimen simulating wellbore sealing device according to claim 8, characterized in that: The outer surface of the circular shaft (2101) is fixedly connected to a rubber sealing plate (314), the outer surface of the rubber sealing plate (314) is in contact with the inner wall of the limiting cylinder (303), the top end of the long shaft (306) passes through the circular shaft (2101) and extends to the top of the circular shaft (2101), the top end of the long shaft (306) is fixedly connected to a force plate (301), the top end of the limiting cylinder (303) is in contact with the bottom end of the circular cylinder (2203), the bottom end of the limiting cylinder (303) is in contact with the top end of the rubber ring (2110), the upper surface of the first folding rubber pad (312) is in contact with the bottom surface of the circular plate (305), and the upper surface of the second folding rubber pad (309) is in contact with the inner top wall of the circular shaft (2101).

10. A method for simulating a wellbore sealing device with a hydraulic fracturing test specimen according to any one of claims 1 to 9, characterized in that: The specific steps include: S1: Place the first opening pad (2108) on the upper surface of the rock sample (1), and then apply a rotational force to the second opening pad (2107), driving the second opening pad (2107) and the upper fixed connecting plate (2106) and the stud (2104) to rotate. When the stud (2104) rotates, it will use the threaded connection relationship to push the lifting block (2105) to move upward. As the second opening pad (2107) continues to rotate, it will eventually push the lifting block (2105) to contact the bottom surface of the ring (2102), thereby pushing the ring (2102) and the circular shaft (2101) to move upward. When the circular shaft (2101) moves upward, it will drive the expansion cone (2109) to move upward synchronously, so that the expansion cone (2109) will squeeze into the interior of the rubber ring (2110), so that the rubber ring (2110) expands and closely contacts the inner wall of the rock sample (1), thereby achieving the purpose of sealing; S2: When the limiting unit (22) needs to be used, the connecting ring (2201) can be pressed downward. When the connecting ring (2201) moves downward, it will drive the two sliding shafts (2207) to slide along the inside of the sliding groove (2206), thereby pushing the first extrusion block (2208) fixed on the surface of the sliding shaft (2207) to slide in the direction of the pressure block (2204). When the first extrusion block (2208) contacts the pressure block (2204), the first extrusion block (2208) will push the pressure block (2204) to move toward the rock sample (1). Finally, the surface of the pressure block (2204) will contact the inner wall of the rock sample (1), thereby limiting the circular cylinder (2203) and the first opening pad (2108); S3: The force-bearing plate (301) can be pulled to move upward. When the force-bearing plate (301) moves upward, the long axis (306) and the circular plate (305) fixed at the bottom end of the long axis (306) will be driven to move upward synchronously, thereby squeezing the air in the space above the circular plate (305) into the space below the circular plate (305). When the circular plate (305) moves upward to a position close to the top of the circular axis (2101), the force-bearing plate (301) can be pushed to move the long axis (306) and the circular plate (305) downward, causing the air to move downward until the air enters the interior of the airbag (302), inflating the airbag (302) and completing the purpose of inflation and sealing.

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