Experimental Device and Experimental Method for Testing Mechanical Properties of Hydrate Reservoirs

Abstract

The present invention provides an experimental device and an experimental method for testing the mechanical properties of a hydrate reservoir. The experimental device for testing the mechanical properties of a hydrate reservoir includes: a reaction kettle, which is provided with a drilling fluid inlet and a drilling fluid outlet; a core shearing mechanism, which includes a shearing driving mechanism and a shearing tool. The shearing tool is arranged in the reaction kettle, and the shearing driving mechanism is connected to the shearing tool. The shearing driving mechanism can drive the shearing tool to move so as to shear a core specimen arranged in the reaction kettle; a core clamping mechanism, which includes a clamping driving mechanism and a supporting mechanism. The clamping driving mechanism is connected to the supporting mechanism. The clamping driving mechanism can drive the supporting mechanism to move to abut against the side wall of the core specimen to prevent the core specimen from moving when being sheared by the shearing tool. By adopting the present invention, it is convenient to study the influence of drilling fluid invasion and erosion on the mechanical properties of a hydrate reservoir.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas exploration and development, and particularly relates to an experimental device and an experimental method for testing the mechanical properties of hydrate reservoirs. Background Art

[0002] Natural gas hydrate is an ice-like crystalline compound formed by water molecules and hydrocarbon gas molecules under low temperature and high pressure conditions. It is also called "flammable ice" or "solid gas", and has the characteristics of high energy density, wide distribution, large reserves, etc. It is a new energy source and alternative energy source with great potential. Natural gas hydrates are widely distributed in permafrost and ocean areas, and the reserves of natural gas stored are relatively abundant.

[0003] Drilling is required for the exploration and development of natural gas hydrates. During the drilling construction process, due to the invasion and erosion of drilling fluid, the hydrate in the reservoir is prone to decomposition, which will change the mechanical properties of the hydrate reservoir, induce wellbore instability, lost circulation, well kick, and even blowout, resulting in safety accidents.

[0004] At present, there are still many unclear points about the influence of drilling fluid invasion and erosion on the mechanical properties of hydrate reservoirs, and there are many difficulties in the research on this influence. Therefore, it adds more difficulties and uncertainties to drilling. Summary of the Invention

[0005] The purpose of the present invention is to provide an experimental device and an experimental method for testing the mechanical properties of hydrate reservoirs, so as to facilitate the study of the influence of drilling fluid invasion and erosion on the mechanical properties of hydrate reservoirs.

[0006] The above object of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides an experimental device for testing the mechanical properties of hydrate reservoirs, including:

[0008] A reaction kettle, which is provided with a drilling fluid inlet and a drilling fluid outlet;

[0009] A core shearing mechanism, which includes a shearing driving mechanism and a shearing tool. The shearing tool is arranged in the reaction kettle, the shearing driving mechanism is connected with the shearing tool, and the shearing driving mechanism can drive the shearing tool to move to shear the core specimen arranged in the reaction kettle;

[0010] A core clamping mechanism, which includes a clamping driving mechanism and a supporting mechanism. The clamping driving mechanism is connected with the supporting mechanism, and the clamping driving mechanism can drive the supporting mechanism to move to abut against the side wall of the core specimen to prevent the core specimen from moving when being sheared by the shearing tool.

[0011] In a preferred embodiment, the support mechanism includes a first arc-shaped plate and a second arc-shaped plate, the first arc-shaped plate and the second arc-shaped plate are arranged opposite to each other, and can move towards each other to abut against opposite sides of the core specimen.

[0012] In a preferred embodiment, the shearing tool moves in the horizontal direction to shear the core specimen.

[0013] In a preferred embodiment, the core clamping mechanism includes at least two of the support mechanisms, and the at least two support mechanisms are respectively arranged above and below the shearing tool.

[0014] In a preferred embodiment, the movement directions of the first arc-shaped plate, the shearing tool, and the second arc-shaped plate are all in the horizontal direction; and, the movement direction of the first arc-shaped plate is staggered from the movement direction of the shearing tool, and the movement direction of the second arc-shaped plate is staggered from the movement direction of the shearing tool.

[0015] In a preferred embodiment, the core clamping mechanism includes at least two of the clamping drive mechanisms, and the first arc-shaped plate and the second arc-shaped plate are respectively connected to the clamping drive mechanisms; the clamping drive mechanism includes a fixed clamping nut and a clamping push rod connected to the clamping nut; in the clamping drive mechanism connected to the first arc-shaped plate, one end of the clamping push rod disposed in the reaction kettle is connected to the first arc-shaped plate, and rotating the clamping push rod relative to the clamping nut can drive the first arc-shaped plate to move towards the core specimen; in the clamping drive mechanism connected to the second arc-shaped plate, one end of the clamping push rod disposed in the reaction kettle is connected to the second arc-shaped plate, and rotating the clamping push rod relative to the clamping nut can drive the second arc-shaped plate to move towards the core specimen.

[0016] In a preferred embodiment, the drilling fluid inlet is connected to a drilling fluid pumping system, and the drilling fluid outlet is connected to a back pressure unloading system.

[0017] In a preferred embodiment, the shearing tool includes a core shearing ring, the core shearing ring can surround the core specimen, and the direction in which the shearing drive mechanism drives the core shearing ring to move is perpendicular to the axial direction of the core shearing ring.

[0018] In a preferred embodiment, the core shearing ring is circular.

[0019] In a preferred embodiment, the shearing drive mechanism includes a shearing motor, a fixedly arranged shearing nut, and a shearing lead screw connected to the shearing nut. The shearing lead screw is perpendicular to the axial direction of the core shearing ring. The first end of the shearing lead screw is connected to the shearing motor, and the second end of the shearing lead screw is connected to the core shearing ring.

[0020] In a preferred embodiment, the shearing drive mechanism includes a shearing connecting rod. A ball head thimble is provided at the second end of the shearing lead screw, and an abutting portion abutting against the ball head thimble is provided at the first end of the shearing connecting rod. The core shearing ring is connected to the second end of the shearing connecting rod.

[0021] In a preferred embodiment, the reaction kettle is provided with a gas injection port.

[0022] In a preferred embodiment, a core placing table for placing the core specimen is provided inside the reaction kettle; the gas injection port is arranged on the tabletop of the core placing table.

[0023] In a preferred embodiment, the experimental device includes a core overburden pressure loading mechanism, and the core overburden pressure loading mechanism can apply downward pressure to the core specimen arranged inside the reaction kettle.

[0024] In a preferred embodiment, the core overburden pressure loading mechanism includes a loading cylinder fixedly arranged at the top of the reaction kettle and a loading plunger installed in the loading cylinder. The loading plunger can move up and down inside the reaction kettle.

[0025] In a preferred embodiment, the reaction kettle includes a body mounting base plate, an upper kettle body, and a lower kettle body. The lower kettle body is installed on the body mounting base plate, and the upper kettle body is detachably installed on the lower kettle body.

[0026] In a preferred embodiment, the experimental device includes a kettle body lifting mechanism. The kettle body lifting mechanism includes a lifting frame body fixedly connected to the body mounting base plate, a lifting nut fixedly connected to the lifting frame body, and a lifting lead screw installed in the lifting nut. The lower end of the lifting lead screw is connected to the upper kettle body.

[0027] In a preferred embodiment, the lifting frame body includes a lifting support plate and a plurality of lifting pull rods. The lifting support plate is located above the upper kettle body. The lifting pull rods are arranged in the vertical direction, and a plurality of the lifting pull rods are distributed around the reaction kettle. The lower ends of the lifting pull rods are fixedly connected to the body mounting base plate, and the upper ends of each of the lifting pull rods are fixedly connected to the lifting support plate; the lifting nut is fixedly connected to the lifting support plate; and, a plurality of linear bushings are provided on the upper kettle body, and the lifting pull rods pass through the linear bushings.

[0028] In a preferred embodiment, a viewing window is provided on the side wall of the reactor.

[0029] The present invention provides an experimental method for testing the mechanical properties of a hydrate reservoir, using the above experimental device for testing the mechanical properties of a hydrate reservoir, including:

[0030] Step S10, placing the core specimen in the reactor;

[0031] Step S21, the clamping drive mechanism drives the support mechanism to move away from the core specimen;

[0032] Step S22, injecting drilling fluid into the reactor through the drilling fluid inlet, and the drilling fluid is discharged through the drilling fluid outlet;

[0033] Step S30, the clamping drive mechanism drives the support mechanism to move to abut against the side wall of the core specimen, and the shear drive mechanism drives the shear tool to move to shear the core specimen.

[0034] In a preferred embodiment, the step S10 includes:

[0035] Step S11, placing the core skeleton in the reactor;

[0036] Step S12, performing a vacuum treatment on the inside of the reactor;

[0037] Step S13, injecting the gas required for synthesizing hydrate into the reactor so that hydrate is formed inside the core skeleton.

[0038] In a preferred embodiment, the step S10 further includes:

[0039] Step S14, reducing the pressure inside the reactor;

[0040] Step S15, increasing the pressure inside the reactor, injecting the gas required for synthesizing hydrate into the reactor so that hydrate is formed inside the core skeleton;

[0041] The step S14 and the step S15 are sequentially implemented after the step S13.

[0042] The features and advantages of the present invention are:

[0043] When conducting experiments using the experimental device for testing the mechanical properties of hydrate reservoirs, the core clamping mechanism can prevent the core specimen from moving when being sheared by the shear tool, facilitating the core shearing mechanism to shear the core specimen. Before shearing, drilling fluid can be introduced into the reaction kettle through the drilling fluid inlet, and the drilling fluid is discharged through the drilling fluid outlet. The drilling fluid flows in the reaction kettle, exerting invasion and erosion effects on the core specimen. Before introducing the drilling fluid, the clamping drive mechanism in the core clamping mechanism can drive the support mechanism to move away from the core specimen. In this way, it is beneficial for the drilling fluid to fully contact and act on the core specimen, so as to more accurately simulate the invasion and erosion effects of the drilling fluid on the hydrate reservoir and improve the reliability of the experiment.

[0044] The drilling fluid exerts invasion and erosion effects on the core specimen; through shearing, the mechanical properties of the core specimen can be understood. This experimental device can achieve the invasion and erosion of the core specimen by the drilling fluid without transferring the core specimen. Through this experiment simulation, the influence of the invasion and erosion effects of the drilling fluid on the mechanical properties of the hydrate reservoir can be studied. Brief Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0046] Figure 1 It is a side view of the experimental device for testing the mechanical properties of hydrate reservoirs provided by the present invention;

[0047] Figure 2 It is Figure 1 a front view of the experimental device for testing the mechanical properties of hydrate reservoirs shown;

[0048] Figure 3 It is Figure 1 a schematic structural diagram of the reaction kettle in the experimental device for testing the mechanical properties of hydrate reservoirs shown;

[0049] Figure 4 It is Figure 1 a schematic structural diagram of the core clamping mechanism in the experimental device for testing the mechanical properties of hydrate reservoirs shown;

[0050] Figure 5 It is Figure 4 a top view of;

[0051] Figure 6 It is Figure 1 a schematic structural diagram of the core shearing mechanism in the experimental device for testing the mechanical properties of hydrate reservoirs shown;

[0052] Figure 7 Schematic diagram of the cooperation between the shear tool and the core specimen in the experimental device for testing the mechanical properties of hydrate reservoirs shown in Figure 1 Figure

[0053] Figure 8 Schematic diagram of the structure of the overburden pressure loading mechanism on the core in the experimental device for testing the mechanical properties of hydrate reservoirs shown in Figure 1 Figure

[0054] Figure 9 Schematic diagram of the structure of the kettle body lifting mechanism in the experimental device for testing the mechanical properties of hydrate reservoirs shown in Figure 1 Figure

[0055] Figure 10 Schematic diagram of the structure of the viewing window in the experimental device for testing the mechanical properties of hydrate reservoirs shown in Figure 1 Figure

[0056] Figure 11 Schematic diagram of the experimental method for testing the mechanical properties of hydrate reservoirs provided by the present invention.

[0057] Explanation of the reference numerals in the attached drawings:

[0058] 1. Core shearing mechanism; 2. Reaction kettle; 3. Overburden pressure loading mechanism on the core; 4. Kettle body lifting mechanism; 5. Core clamping mechanism; 6. Viewing window; 7. Machine body mounting base plate; 120. Core specimen

[0059] 100. Shearing drive mechanism; 101. Guide rail mounting screw; 102. Linear guide rail pair; 103. Slide block pair; 104. Slide block pair mounting screw; 105. Motor mounting seat; 106. Shearing motor; 107. Motor mounting screw; 108. Coupling; 109. Shearing lead screw; 1091. Shearing nut; 110. Lead screw pair mounting screw; 111. Ball head thimble

[0060] 112. Load sensor; 113. Link mounting screw; 114. Link seal sleeve mounting screw; 115. Link seal sleeve and kettle body seal; 116. Link seal sleeve; 117. Link seal

[0061] 1180. Shearing tool; 118. Core shearing ring

[0062] 119. Shearing connecting rod; 1191. Contact part

[0063] 201. Lifting pull rod

[0064] 202, Drilling fluid inlet; 203, Lower kettle body; 204, Kettle body connection screw; 205, Upper kettle body; 2051, Upper cylinder; 206, Upper cover; 207, Linear bushing; 208, Kettle body upper cover installation screw; 209, Kettle body upper cover seal;

[0065] 210, Pressure sensor; 211, Temperature sensor; 212, Safety valve; 213, Kettle body seal; 214, Kettle body and machine body bottom plate installation screw;

[0066] 215, Drilling fluid outlet; 216, Filter element; 217, Core holding platform; 218, Gas injection port;

[0067] 301, Loading cylinder body installation screw; 302, Loading fluid injection port; 303, Loading cylinder; 304, Loading fluid overflow port; 305, First loading plunger seal; 306, Loading plunger; 307, Loading plunger seal retaining ring; 308, Second loading plunger seal; 309, Loading pressure head;

[0068] 400, Lifting frame body; 401, Lifting support plate; 402, Support plate locking nut; 403, Lifting lead screw nut pair installation nut; 404, Lifting handwheel; 405, Lifting nut; 406, Lifting lead screw; 407, Lifting flange connection nut; 408, Rolling bearing; 409, Lifting flange; 410, Pressure bearing; 411, Pressure bearing gland; 412, Pressure bearing gland installation screw;

[0069] 500, Clamping drive mechanism; 501, Push rod handwheel; 502, Clamping push rod; 503, Clamping nut; 504, Push rod nut pair installation screw; 505, Push rod seal;

[0070] 506, Support mechanism; 5061, First arc plate; 5062, Second arc plate;

[0071] 507, Push rod anti - detachment flange connection nut; 508, Push rod anti - detachment nut; 509, Push rod anti - detachment flange; 510, Press plate screw; 511, Press plate;

[0072] 601, Visual window gland; 602, Visual window gland installation screw; 603, Visual window sealing pressure ring; 604, Visual window plate; 605, Visual window seal; Detailed implementation manners

[0073] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0074] Embodiment 1

[0075] The present invention provides an experimental device for testing the mechanical properties of a hydrate reservoir, as Figures 1 to 3 shown. The experimental device includes: a reaction kettle 2, a core shearing mechanism 1, and a core clamping mechanism 5; the reaction kettle 2 is provided with a drilling fluid inlet 202 and a drilling fluid outlet 215; the core shearing mechanism 1 includes a shearing driving mechanism 100 and a shearing tool 1180. The shearing tool 1180 is arranged in the reaction kettle 2, and the shearing driving mechanism 100 is connected to the shearing tool 1180. The shearing driving mechanism 100 can drive the shearing tool 1180 to move to shear a core specimen 120 arranged in the reaction kettle 2; the core clamping mechanism 5 includes a clamping driving mechanism 500 and a supporting mechanism 506. The clamping driving mechanism 500 is connected to the supporting mechanism 506. The clamping driving mechanism 500 can drive the supporting mechanism 506 to move to abut against the side wall of the core specimen 120 to prevent the core specimen 120 from moving when being sheared by the shearing tool 1180.

[0076] When conducting an experiment using the experimental device for testing the mechanical properties of a hydrate reservoir, the core clamping mechanism 5 can prevent the core specimen 120 from moving when being sheared by the shearing tool 1180, facilitating the core shearing mechanism 1 to shear the core specimen 120. Before shearing, drilling fluid can be introduced into the reaction kettle 2 through the drilling fluid inlet 202, and the drilling fluid is discharged through the drilling fluid outlet 215. The drilling fluid flows in the reaction kettle 2, exerting an intrusion and erosion effect on the core specimen 120. Before introducing the drilling fluid, the clamping driving mechanism 500 in the core clamping mechanism 5 can drive the supporting mechanism 506 to move away from the core specimen 120. In this way, it is beneficial for the drilling fluid to come into full contact with and act on the core specimen 120, so as to more accurately simulate the intrusion and erosion effect of the drilling fluid on the hydrate reservoir and improve the reliability of the experiment.

[0077] The drilling fluid exerts an intrusion and erosion effect on the core specimen 120; through shearing, the mechanical properties of the core specimen 120 can be understood. This experimental device can realize the intrusion and erosion of the core specimen by the drilling fluid without transferring the core specimen 120. Through this experiment simulation, the influence of the intrusion and erosion effect of the drilling fluid on the mechanical properties of the hydrate reservoir can be studied.

[0078] In an embodiment of the present invention, as Figure 3As shown, the reactor includes a body mounting base plate 7, an upper kettle body 205, and a lower kettle body 203. The lower kettle body 203 is mounted on the body mounting base plate 7, and the upper kettle body 205 is detachably mounted on the lower kettle body 203. The drilling fluid inlet 202 is provided on the lower kettle body 203, and the drilling fluid outlet 215 is provided on the upper kettle body 205. An end face seal is provided between the upper kettle body 205 and the lower kettle body 203. The upper kettle body includes an upper cover 206 and an upper cylinder body 2051. The upper cylinder body 2051 is fixedly connected to the lower kettle body 203, and the upper cover 206 is mounted on the upper cylinder body 2051 by bolts. The drilling fluid outlet 215 is provided on the upper cover 206. Specifically, the reactor 2 further includes kettle body connection screws 204, kettle body upper cover mounting screws 208, kettle body upper cover seals 209, kettle body seals 213, and kettle body and body bottom plate mounting screws 214. The upper kettle body 205 and the lower kettle body 203 are subjected to end face seal by the kettle body connection screws 204 and the kettle body seals 213.

[0079] To facilitate the installation of the core specimen 120, a core placing platform 217 is provided in the reactor 2, and the core specimen 120 can be placed on the core placing platform 217. The core specimen 120 can be columnar, and its axis is arranged in the vertical direction; the shearing tool 1180 is arranged above the core placing platform 217, and the shearing tool 1180 can move horizontally to shear the core specimen 120 placed on the core placing platform 217; the support mechanism 506 is arranged above the core placing platform 217, and the support mechanism 506 can move to abut against the side wall of the core specimen 120 placed on the core placing platform 217.

[0080] The support mechanism 506 is used to support the core specimen 120. The structural form of the support mechanism 506 is not limited to one kind. For example: the support mechanism 506 can be in the shape of a flat plate, and the flat plate-shaped support mechanism 506 and the core shearing mechanism 1 can be arranged on the opposite sides of the core specimen 120, so that the support mechanism 506 can provide a reaction force for the core specimen 120 during shearing. The inventor has improved the support mechanism 506: the support mechanism 506 includes a first arc-shaped plate 5061 and a second arc-shaped plate 5062, as Figure 4 and Figure 5As shown, the first curved plate 5061 and the second curved plate 5062 are arranged opposite to each other and can move toward each other to abut against the opposite sides of the core specimen 120. The first curved plate 5061 and the second curved plate 5062 are respectively provided with arc surfaces, which can cooperate with the side walls of the cylindrical core specimen 120. When the first curved plate 5061 and the second curved plate 5062 are both moved to abut against the core specimen 120, they can provide stable support for the core specimen 120 together. A larger contact area can be generated between the first curved plate 5061 and the core specimen 120 and between the second curved plate 5062 and the core specimen 120, which is conducive to making the support more stable; at the same time, when the clamping drive mechanism 500 drives the first curved plate 5061 and the second curved plate 5062 to deviate from the core specimen 120, the side walls of the core specimen 120 are exposed, which can fully contact and act with the drilling fluid. In order to make the core specimen 120 fully contact with the drilling fluid, the first curved plate 5061 and the second curved plate 5062 can be opened during the flow of the drilling fluid. After the flow time reaches the experimental design time, the first curved plate 5061 and the second curved plate 5062 are closed and the direct shear test of the core specimen is carried out.

[0081] The movement direction of the first curved plate 5061, the movement direction of the shearing tool 1180, and the movement direction of the second curved plate 5062 may all be in the horizontal direction. The movement direction of the first curved plate 5061 and the movement direction of the second curved plate 5062 may be parallel. Figures 3 to 5 As shown, the movement direction of the first arc plate 5061 is staggered with the movement direction of the shearing tool 1180, and the movement direction of the second arc plate 5062 is staggered with the movement direction of the shearing tool 1180; preferably, the movement direction of the first arc plate 5061 is perpendicular to the movement direction of the shearing tool 1180.

[0082] The core clamping mechanism 5 includes at least two clamping drive mechanisms 500, such as Figure 4 and Figure 5As shown, a clamping drive mechanism 500 is respectively connected to the first arc-shaped plate 5061 and the second arc-shaped plate 5062; the clamping drive mechanism 500 includes a fixed clamping nut 503 and a clamping push rod 502 connected to the clamping nut 503; in the clamping drive mechanism 500 connected to the first arc-shaped plate 5061, one end of the clamping push rod 502 disposed in the reaction kettle 2 is connected to the first arc-shaped plate 5061. Rotating the clamping push rod 502 relative to the clamping nut 503 can drive the first arc-shaped plate 5061 to move towards the core specimen 120; in the clamping drive mechanism 500 connected to the second arc-shaped plate 5062, one end of the clamping push rod 502 disposed in the reaction kettle 2 is connected to the second arc-shaped plate 5062. Rotating the clamping push rod 502 relative to the clamping nut 503 can drive the second arc-shaped plate 5062 to move towards the core specimen 120. The clamping nut 503 and the clamping push rod 502 form a lead screw pair. Rotating the clamping push rod 502 can make the clamping push rod 502 move along its axial direction; as Figure 4 As shown, the clamping push rod is connected with a push rod handwheel 501, so that the operator can manually drive the clamping push rod 502 to rotate through the push rod handwheel 501 to adjust the positions of the first arc-shaped plate 5061 and the second arc-shaped plate 5062.

[0083] Specifically, the core clamping mechanism 5 further includes a push rod nut pair mounting screw 504, a push rod seal 505, a push rod anti-drop flange connection nut 507, a push rod anti-drop nut 508, a push rod anti-drop flange 509, a pressing plate screw 510 and a plurality of pressing plates 511. The plurality of pressing plates 511 are respectively in contact with the first arc-shaped plate 5061 and the second arc-shaped plate 5062, and play a guiding role in the movement of the first arc-shaped plate 5061 and the second arc-shaped plate 5062. The push rod handwheel 501 drives the opening and closing of the first arc-shaped plate 5061 and the second arc-shaped plate 5062 in the horizontal direction, thereby meeting the key requirement of sufficient contact and interaction between the drilling fluid and the core specimen 120.

[0084] The support mechanism 506 can be arranged above the shear tool 1180 or below the shear tool 1180. In order to further improve the stability of the core specimen 120 during shearing, the core clamping mechanism 5 includes at least two support mechanisms 506, such as Figure 3 As shown, at least two support mechanisms 506 are respectively arranged above the shear tool 1180 and below the shear tool 1180.

[0085] In the core shearing mechanism 1, the shearing drive mechanism 100 drives the shear tool 1180 to move to shear the core specimen 120. The structural form of the shear tool 1180 is not limited to one kind. For example: the shear tool 1180 can be in a flat plate shape, and its shearing surface is arranged along the horizontal plane. The inventor has improved the shear tool 1180: as Figure 7As shown in the figure, the core cutting tool 1180 includes a core cutting ring 118. The core cutting ring 118 can surround the core specimen 120. The direction in which the cutting drive mechanism 100 drives the core cutting ring 118 to move is perpendicular to the axial direction of the core cutting ring 118. With this structural form, when the core cutting tool 1180 performs cutting, the distribution of the shearing force received by the core specimen 120 is more uniform, which is beneficial to making the cutting process smoother. The core cutting ring 118 cuts the core specimen 120 into upper and lower parts. Since during the cutting process, the core cutting ring 118 contacts the upper and lower parts respectively, the upper and lower parts respectively have shear surfaces. Therefore, by using the core cutting ring 118, the cut part of the core specimen 120 has two shear surfaces, namely the upper and lower shear surfaces. By using the core cutting ring 118, direct cutting of the core specimen 120 before and after the action of the drilling fluid is realized, which is beneficial to achieving full contact and interaction between the drilling fluid and the core specimen 120.

[0086] Preferably, as Figure 7 shown, the core cutting ring 118 is in a circular ring shape.

[0087] In an embodiment of the present invention, the cutting drive mechanism 100 includes a cutting motor 106, a fixed cutting nut 1091, and a cutting lead screw 109 connected to the cutting nut 1091. The cutting lead screw 109 is perpendicular to the axial direction of the core cutting ring 118. The first end of the cutting lead screw 109 is connected to the cutting motor 106, and the second end of the cutting lead screw 109 is connected to the core cutting ring 118. The cutting lead screw 109 and the cutting nut 1091 form a lead screw pair. The cutting motor 106 drives the cutting lead screw 109 to rotate, so that the cutting lead screw 109 drives the core cutting ring 118 to move along the axial direction of the cutting lead screw 109 together to achieve cutting.

[0088] Specifically, as Figure 6 shown, the core cutting mechanism 1 further includes a guide rail mounting screw 101, a linear guide rail pair 102, a slider pair 103, a slider pair mounting screw 104, a motor mounting seat 105, a motor mounting screw 107, a coupling 108, a lead screw pair mounting screw 110, a connecting rod mounting screw 113, a connecting rod seal sleeve mounting screw 114, a connecting rod seal sleeve and kettle body seal 115, a connecting rod seal sleeve 116, and a connecting rod seal 117. By rotating the cutting motor 106, the coupling 108 drives the cutting lead screw 109 to displace, pushing the core cutting ring 118 to directly cut the core specimen 120 with a certain force, and controlling and calculating the displacement of the cutting lead screw 109 according to the rotation speed of the cutting motor 106 to achieve cutting the core specimen 120 at different rates.

[0089] Furthermore, the cutting drive mechanism 100 includes a cutting connecting rod 119, as Figure 6As shown, a ball head thimble 111 is provided at the second end of the shearing lead screw 109, and an abutting portion 1191 that abuts against the ball head thimble 111 is provided at the first end of the shearing connecting rod 119. The core shearing ring 118 is connected to the second end of the shearing connecting rod 119. By matching the ball head thimble 111 with the abutting portion 1191, the thrust is transmitted, which is beneficial to keeping the direction of the thrust transmitted from the shearing lead screw 109 to the core shearing ring 118 stable; moreover, when the core shearing ring 118 shears the core specimen 120, it will receive the reaction force of the core specimen 120. Adopting this structural form to transmit the thrust can reduce the interference of the reaction force of the core specimen 120 on the operation of the shearing motor 106. Preferably, the abutting portion 1191 is a plane arranged in the vertical direction. A load sensor 112 can be provided on the shearing connecting rod 119, such as Figure 6 and Figure 7 shown, the abutting portion 1191 is arranged on the stress surface of the load sensor 112, and the load sensor 112 is connected to a computer, and the experimental data is read and recorded through the supporting software.

[0090] In an embodiment of the present invention, a drilling fluid inlet 202 is connected to a drilling fluid pumping system, and a back pressure unloading system is connected to a drilling fluid outlet 215. By adjusting the drilling fluid pumping system and the back pressure unloading system, the drilling fluid enters the reaction kettle 2 from the drilling fluid inlet 202 at a set pressure and rate, and flows out from the drilling fluid outlet 215, so that the drilling fluid fully acts on the core specimen 120, and the flowing time of the drilling fluid is controllable.

[0091] Furthermore, the drilling fluid pumping system is a temperature-controllable drilling fluid pumping system, and its cooperation with the back pressure unloading system realizes the flow of the drilling fluid in the reaction kettle 2 under different temperature, pressure, flow rate and duration conditions. Specifically, the drilling fluid pumping system includes a constant pressure and constant flow pump and a temperature-controllable piston container for storing the drilling fluid; the constant pressure and constant flow pump pumps water into the piston container to drive the temperature-controlled drilling fluid into the interior of the reaction kettle. A safety valve is also connected to the drilling fluid outlet 215. The drilling fluid pumping system, the safety valve 212 and the back pressure unloading system jointly realize the constant temperature, constant pressure, constant speed and constant time flow of the drilling fluid inside the reaction kettle 2. The back pressure unloading system can include a back pressure unloading valve, a gas flow meter and a liquid metering and collecting container.

[0092] This experimental device can control the drilling fluid to flow in the reaction kettle 2 at a set temperature, pressure and injection rate, so as to quantitatively study the influence of the invasion and erosion of the drilling fluid on the mechanical properties of different buried deep hydrate reservoirs under dynamic conditions, and study the change of the mechanical properties of hydrate reservoirs with different occurrence conditions during the drilling process due to the invasion and erosion of the drilling fluid, providing valuable reference and support for the safe and efficient exploration and development of natural gas hydrates, and also providing important support for the safe and efficient drilling of frozen soil and marine natural gas hydrates.

[0093] A temperature sensor 211 and a pressure sensor 210 are provided in the reaction kettle 2. As Figure 3 shown, the temperature sensor 211 and the pressure sensor 210 can be arranged at the drilling fluid outlet 215. During the experiment, the experimental device is placed in an air bath box for temperature control. The pressure sensor 210 and the temperature sensor 211 are connected to a computer, and the temperature and pressure conditions inside the reaction kettle 2 are monitored in real time through the supporting software.

[0094] When using this experimental device for experiments, the prepared core specimen 120 can be placed in the reaction kettle 2 to directly start the experiment. In an embodiment of the present invention, the reaction kettle 2 is provided with a gas injection port 218, and the preparation of the core specimen 120 can be realized in the reaction kettle 2, and then a shear experiment is carried out. Specifically, the core skeleton is placed on the core holding table 217, and the gas required to form hydrate is injected into the reaction kettle 2 through the gas injection port 218, and the pressure and temperature inside the reaction kettle 2 are adjusted so that hydrate is formed inside the core skeleton under a low-temperature and high-pressure environment to prepare the core specimen 120. This experimental device can prepare core specimens 120 with different saturations. The internal pressure of the reaction kettle 2 can be jointly regulated by the gas injection port 218, the safety valve 212 connected to the drilling fluid outlet 215, and the back pressure unloading system. The gas injection port 218 is connected with a pressure control device to facilitate the regulation of the internal pressure of the reaction kettle 2. The pressure control device can include a gas source, a gas booster pump, and a booster console.

[0095] Furthermore, the gas injection port 218 is arranged on the tabletop of the core holding table 217. When preparing the core specimen 120, the core skeleton is placed on the core holding table 217, and the gas is injected from the bottom of the core skeleton, which can more efficiently displace the residual air inside the core skeleton and effectively improve the saturation of hydrate in the core specimen 120.

[0096] A filter element 216 is provided in the core holding table 217, and the gas injection port 218 is communicated with the reaction kettle 2 through the filter element 216. During the experiment, the core skeleton is placed on the core holding table 217, and the gas required to form hydrate is injected into the reaction kettle 2 from the gas injection port 218 through the filter element 216 that prevents solid-phase blockage.

[0097] In an embodiment of the present invention, the experimental device includes a core overburden pressure loading mechanism, and the core overburden pressure loading mechanism can apply a downward pressure to the core specimen 120 arranged in the reaction kettle. By applying a certain overburden pressure to the core specimen 120 through the core overburden pressure loading mechanism, and then setting up a core shear mechanism to shear the core specimen 120 with a certain horizontal shear force and shear rate, the mechanical strength of the core specimen 120 and the mechanical strength of the hydrate reservoir can be evaluated under different overburden pressure conditions.

[0098] Furthermore, the overburden pressure loading mechanism 3 of the core includes a loading cylinder 303 fixedly arranged at the top of the reaction kettle 2 and a loading plunger 306 installed in the loading cylinder 303. The loading plunger 306 can move up and down in the reaction kettle 2. Preferably, as Figure 3 shown, the first arc-shaped plate 5061 and the second arc-shaped plate 5062 are distributed around the axis of the loading plunger 306. A loading head 309 is connected to the lower end of the loading plunger 306 to facilitate abutting against the core specimen 120 and applying a downward pressure. The loading plunger 306 is controlled by injecting and discharging liquid, and cooperates with the loading head 309, etc. to apply the overburden pressure to the core specimen 120 placed inside the reaction kettle 2. Specifically, as Figure 8 shown, the overburden pressure loading mechanism 3 of the core further includes loading cylinder body mounting screws 301, a loading liquid injection port 302, a loading liquid overflow port 304, a first loading plunger seal 305, a loading plunger seal retaining ring 307 and a second loading plunger seal 308. The first loading plunger seal 305 is installed on the loading plunger 306 and is slidably mated with the inner wall of the loading cylinder 303; both the loading plunger seal retaining ring 307 and the second loading plunger seal 308 are installed on the inner wall of the loading cylinder 303 and are slidably mated with the outer wall of the loading plunger 306.

[0099] In an embodiment of the present invention, the experimental device includes a kettle body lifting mechanism 4. The kettle body lifting mechanism 4 includes a lifting frame body 400 fixedly connected to the body mounting base plate 7, a lifting nut 405 fixedly connected to the lifting frame body 400, and a lifting lead screw 406 installed in the lifting nut 405. The lower end of the lifting lead screw 406 is connected to the upper kettle body 205. The lifting nut 405 and the lifting lead screw 406 form a lead screw pair. By rotating the lifting lead screw 406, an upward lifting force is generated by the lifting lead screw 406, which can drive the upper kettle body 205 to move upward. Specifically, as Figure 9 shown, the lower end of the lifting lead screw 406 is connected to the loading cylinder 303 connected to the upper cover 206.

[0100] Furthermore, the lifting frame body 400 includes a lifting support plate 401 and a plurality of lifting pull rods 201. The lifting support plate 401 is located above the upper kettle body 205. The lifting pull rods 201 are arranged in the vertical direction. The plurality of lifting pull rods 201 are distributed around the reaction kettle 2. The lower ends of the lifting pull rods 201 are fixedly connected to the body mounting base plate 7, and the upper ends of each of the lifting pull rods 201 are fixedly connected to the lifting support plate 401; the lifting nut 405 is fixedly connected to the lifting support plate 401; as Figure 3 and Figure 9As shown in the figure, a linear bushing 207 is provided on the upper cover 206 of the upper kettle body 205. The lifting pull rod 201 passes through the linear bushing 207, and the lifting pull rod 201 can smoothly slide up and down in the linear bushing 207. When lifting the upper cover 206, the upper cover 206 moves along the lifting pull rod 201, and the lifting pull rod 201 can play a guiding role to make the lifting action more stable.

[0101] Specifically, as Figure 9 shown, the kettle body lifting mechanism 4 further includes a support plate locking nut 402, a lifting lead screw nut pair mounting nut 403, a lifting handwheel 404, a lifting flange connection nut 407, a rolling bearing 408, a lifting flange 409, a pressure bearing 410, a pressure bearing gland 411 and a pressure bearing gland mounting screw 412. The lifting handwheel 404 is connected to the lifting lead screw 406 through a shaft and a key; the lifting support plate 401 and the lifting pull rod 201 are connected through the support plate locking nut 402; the lifting lead screw 406 and the upper cover 206 can rotate relative to each other. The lower part of the lifting lead screw 406, the rolling bearing 408 and the pressure bearing 410 are fixed on the lifting flange 409 through the lifting flange connection nut 407 and are connected to the loading cylinder 303. When manually shaking the lifting handwheel 404, the up and down movement of the upper cover 206 is realized.

[0102] In an embodiment of the present invention, a viewing window 6 is provided on the side wall of the reaction kettle 2. Through the viewing window 6, it is convenient to observe the shearing process of the core specimen 120. Preferably, the viewing window 6 is provided on the side wall of the upper cylinder 2051 of the upper kettle body 205. Specifically, as Figure 3 and Figure 10 shown, the viewing window 6 is provided on the front of the upper kettle body 205 and includes a viewing window gland 601, a viewing window gland mounting screw 602, a viewing window sealing ring 603, a viewing window plate 604 and a viewing window seal 605. The viewing window plate 604 is integrally pressed and sealed through the viewing window sealing ring 603 and the viewing window seal 605, as well as the viewing window gland 601 and the viewing window gland mounting screw 602. Through the viewing window plate 604, the dynamic experimental phenomena such as the flow characteristics of the drilling fluid, the physical property evolution of the core specimen 120 and the direct shear of the core during the experiment can be observed.

[0103] This experimental device has the following advantages:

[0104] (1) This experimental device can be used to prepare core specimens with different saturations in the laboratory and can simulate the invasion and erosion of the core by the drilling fluid without transferring the core;

[0105] (2) This experimental device can evaluate the mechanical strength of the hydrate reservoir by directly shearing with the shearing tool 1180 under different overburden pressure conditions;

[0106] (3) This experimental device can enable the drilling fluid to flow in the reaction kettle under the conditions of constant temperature and constant speed, and can fully contact and act with the core specimen 120. During the flow of the drilling fluid, the pressure in the reaction kettle is controllable, and the flow time of the drilling fluid is controllable. By collecting in real time the internal temperature and pressure data of the reaction kettle, the overburden pressure data of the core, the flow rate of the drilling fluid, and the direct shear data of the core, etc., and observing and recording the experimental phenomena in the reaction kettle 2 through the visual window 6 throughout the process, and then based on the comparison of the direct shear experimental data under the conditions of the presence and absence of drilling fluid invasion and erosion, comprehensively analyze the influence of drilling fluid invasion and erosion on the mechanical properties of the hydrate reservoir;

[0107] (4) This experimental device is close to the actual natural gas hydrate drilling working conditions, and the system structure is scientific and reliable, easy to operate, and the experiment has strong repeatability; it has important reference value for the research and development of the hydrate drilling fluid system, provides a more reliable guarantee for the safe and efficient drilling of hydrates in frozen soil and marine areas, and has important economic and social benefits for the global exploration and development of natural gas hydrates; it can also be used for the scientific experiments and research of hydrates in relevant scientific research institutes, and provide devices and technical services for drilling fluid testing for oil drilling and geological exploration related enterprises and scientific research institutes.

[0108] Example Two

[0109] The present invention provides an experimental method for testing the mechanical properties of a hydrate reservoir, using the above-mentioned experimental device for testing the mechanical properties of a hydrate reservoir, as Figure 11 shown. This experimental method includes: Step S10, setting the core specimen 120 in the reaction kettle 2; Step S21, the clamping drive mechanism 500 drives the support mechanism 506 to move away from the core specimen 120; Step S22, introducing the drilling fluid into the reaction kettle 2 through the drilling fluid inlet 202, and the drilling fluid is discharged through the drilling fluid outlet 215; Step S30, the clamping drive mechanism 500 drives the support mechanism 506 to move to abut against the side wall of the core specimen 120, and the shear drive mechanism 100 drives the shear tool 1180 to move to shear the core specimen 120.

[0110] Shearing the core specimen 120 with the shear tool 1180 can understand the mechanical properties of the core specimen 120. A certain overburden pressure can be loaded on the core specimen 120 through the core overburden pressure loading mechanism 3, and then the core shear mechanism 1 is set to directly shear the core specimen 120 with a certain horizontal shear force and shear rate. Collect in real time the internal temperature and pressure data of the reaction kettle 2, the overburden pressure data of the core, the flow rate of the drilling fluid, and the direct shear data of the core, etc., and observe and record the experimental phenomena in the kettle through the visual window throughout the process, and comprehensively analyze the influence of drilling fluid invasion and erosion on the mechanical properties of the core specimen 120.

[0111] The drilling fluid invades and erodes the core specimen 120, and the support mechanism 506 moves away from the core specimen 120, which is conducive to the full contact and interaction between the drilling fluid and the core specimen 120, so as to more accurately simulate the invasion and erosion of the drilling fluid on the hydrate reservoir and improve the reliability of the experiment.

[0112] Two sets of comparative experiments can be carried out: in the first set of comparative experiments, steps S21 and S22 are implemented; in the second set of comparative experiments, steps S21 and S22 are not implemented. Through comparison, it is convenient to understand the influence of the invasion and erosion of the drilling fluid on the core specimen 120. Specifically, in the first set of comparative experiments, steps S21 and S22: after applying the same overburden pressure as in step S30 of core loading, open the first arc plate 5061 and the second arc plate 5062, and by adjusting the drilling fluid injection system and the back pressure unloading system, make the drilling fluid enter the reaction kettle from the drilling fluid inlet 202 at a certain temperature, pressure and rate, and flow out from the drilling fluid outlet 215, ensuring full interaction between the drilling fluid and the core specimen 120 and controllable drilling fluid flow time; when steps S21 and S22 reach the experimental design conditions, the core shearing mechanism 1 can be set to directly shear the core specimen 120 with the same horizontal shearing force and shearing rate as in step S30 of the second set of comparative experiments.

[0113] In step S10, the prepared core specimen 120 can be directly placed in the reaction kettle 2, or the core specimen 120 can be prepared in the reaction kettle 2. Specifically, step S10 includes: step S11, setting the core skeleton in the reaction kettle 2; step S12, performing a vacuum treatment on the inside of the reaction kettle 2; step S13, injecting the gas required for synthesizing hydrate into the reaction kettle 2 to form hydrate inside the core skeleton to prepare the core specimen 120. Specifically, step S10: putting the indoor pressed core skeleton containing saturated water into the support mechanism 506 held inside the reaction kettle 2, sealing the reaction kettle 2 and then performing a vacuum treatment on the inside of the reaction kettle 2, and then injecting the gas required for synthesizing hydrate from the gas injection port 218, and adjusting the pressure and temperature inside the reaction kettle 2 to form hydrate inside the core skeleton under a low temperature and high pressure environment.

[0114] Further, step S10 further includes: step S14, reducing the pressure in the reactor 2; step S15, increasing the pressure in the reactor 2, injecting the gas required for synthesizing the hydrate into the reactor 2, so that the hydrate is formed inside the core skeleton; steps S14 and S15 are sequentially implemented after step S13. After the hydrate basically stops forming in step S13, through step S14, the pressure in the high-pressure reactor 2 is reduced to promote the decomposition of the hydrate, and then through step S15, the foregoing hydrate formation process is repeated. After the hydrate no longer forms in the core, this step is completed. This is beneficial to increasing the hydrate saturation inside the core specimen 120.

[0115] In one embodiment, the vacuum pressure in step S12 is maintained at about -0.08 MPa, and the vacuum time is 30 to 90 min. Step S13 is to form the hydrate inside the core skeleton under the environment of a temperature of 0 to 15 °C and a pressure of 5 to 20 MPa. The gas required for step S13 is selected from one or more of natural gas, methane, nitrogen, and carbon dioxide. The overburden pressure on the core in steps S30, S21, and S22 is 0 to 20 MPa.

[0116] The core shear force in step S30 is 0 to 2000 N, the shear rate is 0 to 1500 γ / mm / min, and the shear displacement is 0 to 2.5 cm. The pressure in the reactor under the flowing condition of the drilling fluid in step S22 is 5 to 18 MPa, the temperature of the drilling fluid is 0 to 30 °C, and the flowing rate of the drilling fluid is 0 to 60 mL / min.

[0117] The above are only several embodiments of the present invention. Those skilled in the art can make various changes or modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention based on the content disclosed in the application documents.

Claims

1. An experimental device for testing the mechanical properties of a hydrate reservoir, characterized in that, it includes: A reaction kettle, which is provided with a drilling fluid inlet and a drilling fluid outlet; A core shearing mechanism, which includes a shearing driving mechanism and a shearing tool. The shearing tool is arranged in the reaction kettle. The shearing driving mechanism is connected to the shearing tool, and the shearing driving mechanism can drive the shearing tool to move to shear the core specimen arranged in the reaction kettle; A core clamping mechanism, which includes a clamping driving mechanism and a supporting mechanism. The clamping driving mechanism is connected to the supporting mechanism, and the clamping driving mechanism can drive the supporting mechanism to move to abut against the side wall of the core specimen to prevent the core specimen from moving when being sheared by the shearing tool; The core clamping mechanism includes at least two of the supporting mechanisms, and at least two of the supporting mechanisms are respectively arranged above and below the shearing tool; The shearing tool includes a core shearing ring, the core shearing ring can surround the core specimen, the direction in which the shearing driving mechanism drives the core shearing ring to move is perpendicular to the axis of the core shearing ring, and the shearing driving mechanism can drive the core shearing ring to move to cut the core specimen into upper and lower parts; The drilling fluid inlet and the drilling fluid outlet are used to introduce circulating drilling fluid into the reaction kettle to exert an intrusion and erosion effect on the hydrate in the core specimen.

2. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, characterized in that, The supporting mechanism includes a first arc-shaped plate and a second arc-shaped plate. The first arc-shaped plate and the second arc-shaped plate are arranged oppositely and can move towards each other to abut against the opposite sides of the core specimen.

3. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1 or claim 2, characterized in that, The shearing tool moves in the horizontal direction to shear the core specimen.

4. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 2, characterized in that, The movement directions of the first arc-shaped plate, the shearing tool, and the second arc-shaped plate are all in the horizontal direction; and, the movement direction of the first arc-shaped plate is staggered from the movement direction of the shearing tool, and the movement direction of the second arc-shaped plate is staggered from the movement direction of the shearing tool.

5. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 2, characterized in that, The core clamping mechanism includes at least two of the clamping driving mechanisms, and the first arc-shaped plate and the second arc-shaped plate are respectively connected to the clamping driving mechanisms; The clamping driving mechanism includes a fixed clamping nut and a clamping push rod connected to the clamping nut; In the clamping driving mechanism connected to the first arc-shaped plate, the end of the clamping push rod arranged in the reaction kettle is connected to the first arc-shaped plate. Rotating the clamping push rod relative to the clamping nut can drive the first arc-shaped plate to move towards the core specimen; In the clamping drive mechanism connected to the second arc-shaped plate, one end of the clamping push rod disposed inside the reaction kettle is connected to the second arc-shaped plate. Rotating the clamping push rod relative to the clamping nut can drive the second arc-shaped plate to move towards the core specimen.

6. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, characterized in that a drilling fluid inlet is connected to a drilling fluid pumping system, and a backpressure unloading system is connected to the drilling fluid outlet.

7. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, characterized in that the core shear ring is in a circular ring shape.

8. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, characterized in that the shear drive mechanism includes a shear motor, a fixedly installed shear nut, and a shear lead screw connected to the shear nut. The shear lead screw is perpendicular to the axial direction of the core shear ring. The first end of the shear lead screw is connected to the shear motor, and the second end of the shear lead screw is connected to the core shear ring.

9. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 8, characterized in that the shear drive mechanism includes a shear connecting rod. A ball head thimble is provided at the second end of the shear lead screw. An abutting portion that abuts against the ball head thimble is provided at the first end of the shear connecting rod. The core shear ring is connected to the second end of the shear connecting rod.

10. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, characterized in that the reaction kettle is provided with a gas injection port.

11. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 10, characterized in that a core placing platform for placing the core specimen is provided inside the reaction kettle; the gas injection port is provided on the tabletop of the core placing platform.

12. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, characterized in that the experimental device includes a core overburden pressure loading mechanism, and the core overburden pressure loading mechanism can apply downward pressure to the core specimen disposed inside the reaction kettle.

13. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 12, characterized in that the core overburden pressure loading mechanism includes a loading cylinder fixedly installed at the top of the reaction kettle and a loading plunger installed in the loading cylinder. The loading plunger can move up and down inside the reaction kettle.

14. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, characterized in that the reaction kettle includes a body mounting base plate, an upper kettle body, and a lower kettle body. The lower kettle body is installed on the body mounting base plate, and the upper kettle body is detachably installed on the lower kettle body.

15. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 14, characterized in that The experimental device includes a kettle body lifting mechanism, which includes a lifting frame body fixedly connected to the machine body mounting base plate, a lifting nut fixedly connected to the lifting frame body, and a lifting lead screw installed on the lifting nut. The lower end of the lifting lead screw is connected to the upper kettle body.

16. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 15, wherein, the lifting frame body includes a lifting support plate and a plurality of lifting tie rods. The lifting support plate is located above the upper kettle body. The lifting tie rods are arranged in the vertical direction, and the plurality of lifting tie rods are distributed around the reaction kettle. The lower ends of the lifting tie rods are fixedly connected to the machine body mounting base plate, and the upper ends of each of the lifting tie rods are fixedly connected to the lifting support plate; the lifting nut is fixedly connected to the lifting support plate; and, the upper kettle body is provided with a plurality of linear bushings, and the lifting tie rods are inserted through the linear bushings.

17. The experimental device for testing the mechanical properties of a hydrate reservoir according to claim 1, wherein, a viewing window is provided on the side wall of the reaction kettle.

18. An experimental method for testing the mechanical properties of a hydrate reservoir, wherein, using the experimental device for testing the mechanical properties of a hydrate reservoir according to any one of claims 1-17, including: Step S10, placing the core specimen in the reaction kettle; Step S21, the clamping drive mechanism drives the support mechanism to move away from the core specimen; Step S22, injecting drilling fluid into the reaction kettle through the drilling fluid inlet, and the drilling fluid is discharged through the drilling fluid outlet; Step S30, the clamping drive mechanism drives the support mechanism to move to abut against the side wall of the core specimen, and the shear drive mechanism drives the shear tool to move to shear the core specimen.

19. The experimental method for testing the mechanical properties of a hydrate reservoir according to claim 18, wherein, the step S10 includes: Step S11, placing the core skeleton in the reaction kettle; Step S12, performing a vacuum treatment on the inside of the reaction kettle; Step S13, injecting the gas required for synthesizing hydrate into the reaction kettle so that hydrate is formed inside the core skeleton.

20. The experimental method for testing the mechanical properties of a hydrate reservoir according to claim 19, wherein, the step S10 further includes: Step S14, reducing the pressure inside the reaction kettle; Step S15, increasing the pressure inside the reaction kettle, injecting the gas required for synthesizing hydrate into the reaction kettle so that hydrate is formed inside the core skeleton; the step S14 and the step S15 are sequentially implemented after the step S13.

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