Core injection-production coupling experimental device and experimental method

Abstract

The present invention discloses a core injection-production coupling experimental device and an experimental method thereof, which relate to the field of geothermal energy development and utilization. The core injection-production coupling experimental device comprises: a core holder, which includes a shell mechanism, an axial pressure loading plunger, an axial pressure bearing plunger mechanism, a first sealing assembly, and a tube body; a heating mechanism for heating the core; a confining pressure generating unit for generating confining pressure, which is connected to the fourth channel; an axial pressure generating unit for generating axial pressure, which is connected to the second channel; a liquid injection unit, which is connected to the first channel; and a liquid recovery unit, which is connected to the third channel. The present application can solve the sealing problem of the core holder under changes in axial pressure and confining pressure under high temperature conditions, thereby completing indoor efficient simulation test research on the flow-heat transfer-deformation-chemical substance migration process.

Description

Technical Field

[0001] The present invention relates to the field of geothermal energy development and utilization, and in particular to a core injection-production coupling experimental device and an experimental method thereof. Background Art

[0002] As a clean and renewable energy source, hot dry rock resources are widely distributed and abundant, and are of great significance to energy structure adjustment and green, coordinated and sustainable development. The Enhanced Geothermal System (EGS) is an artificial geothermal system that fractur- es hot dry rock to form an artificial fracture network between injection and production wells, enhancing rock permeability and economically extracting deep thermal energy by injecting heat transfer fluids. The flow and heat transfer of heat transfer fluids in fractures determine the stability and economic efficiency of the EGS's production capacity. Therefore, the heat-fluid-solid coupled flow and heat transfer mechanism within fractures can provide a basis for better design of hot dry rock thermal reservoir development plans and is a key scientific issue that needs to be addressed urgently.

[0003] Currently, research on this issue primarily relies on numerical simulations. This is because existing testing instruments face issues such as inability to accurately measure test data and seal failure within the core holder when temperatures reach above 200°C. In particular, seal failure results in inaccurate data collected by the testing instruments, making it difficult to truly reflect the parameter changes of hot dry rock under injection and production conditions. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the present invention is to provide a core injection-production coupling experimental device and an experimental method thereof, which can solve the sealing problem of the core clamp under changes in axial pressure and confining pressure under high temperature conditions, thereby completing indoor efficient simulation test research on the flow-heat transfer-deformation-chemical substance migration process.

[0005] The specific technical solution of the embodiment of the present invention is:

[0006] A core injection-production coupling experimental device, comprising:

[0007] The core holder comprises a shell mechanism, an axial pressure loading plunger, an axial pressure bearing plunger mechanism, a first sealing assembly, and a tube body; the upper end face of the shell mechanism has a first opening, the lower end face of the shell mechanism has a second opening, at least part of the axial pressure loading plunger is arranged in the shell mechanism and at least part of the axial pressure loading plunger passes through the first opening, and an axial pressure loading cavity is formed between the axial pressure loading plunger and the shell mechanism, which enables the axial pressure loading plunger to move in the axial direction; at least part of the axial pressure bearing plunger mechanism is arranged in the shell mechanism and at least part of the axial pressure bearing plunger mechanism passes through the second opening; the core is loaded between the axial pressure loading plunger and the axial pressure bearing plunger mechanism; the tube body is sleeved outside the core, the axial pressure loading plunger and the axial pressure bearing plunger mechanism, and the outer side wall of the tube body is adjacent to the shell mechanism a first sealing ring and a second sealing ring are provided on the housing mechanism to seal the first sealing ring; the first sealing ring is located between the first sealing ring and the second sealing ring, and the first sealing ring is located between the first sealing ring and the first sealing ring; the first sealing ring is located between the first sealing ring and the first sealing ring, and the first sealing ring is compressed under pressure to expand the first sealing ring in the radial direction; the axial pressure loading plunger is provided with a first channel that can be communicated with the upper end face of the core, and the axial pressure loading plunger or the housing mechanism is provided with a second channel that is communicated with the axial pressure loading chamber; the axial pressure bearing plunger mechanism is provided with a third channel that can be communicated with the lower end face of the core, and the housing mechanism is provided with a fourth channel that is communicated with the confining pressure loading chamber;

[0008] a heating mechanism for heating the core;

[0009] a confining pressure generating unit for generating confining pressure, connected to the fourth channel;

[0010] an axial pressure generating unit for generating axial pressure, connected to the second channel;

[0011] a liquid injection unit connected to the first channel;

[0012] A liquid recovery unit is connected to the third channel.

[0013] Preferably, the housing mechanism comprises:

[0014] The lockhole that is formed on the upper surface of the piston rod is formed on the upper surface of the piston rod and the lockhole engages with the piston rod of the piston rod at the bottom of the piston rod. The piston rod of the piston rod has a first end in contact with the piston rod of the piston rod. The piston rod of the piston rod has a first end in contact with the piston rod of the piston rod.

[0015] Preferably, the core injection-production coupling experimental device further comprises:

[0016] a second sealing assembly, the second sealing assembly being located between the tube body and the inner sidewall of the housing mechanism to seal the other end of the confining pressure loading chamber, the second sealing assembly comprising a second retaining ring with a lower end resting against the lower cover, a second sealing pressure ring, and a second sealing ring, the second sealing ring being located between the second retaining ring and the second sealing pressure ring, and the second sealing pressure ring being able to compress the second sealing ring under pressure so as to expand the second sealing ring in the radial direction;

[0017] The lower end of the tube body is provided with a lower sleeve body sleeved on the axial pressure bearing plunger mechanism, the lower sleeve body has a second outer edge, and the second outer edge abuts against the axial pressure bearing plunger mechanism; the inner side wall of the second stop ring abuts against the lower sleeve body and the lowermost end of the tube body;

[0018] The heating mechanism includes a heating furnace wrapped around the cylinder.

[0019] Preferably, a cooling cavity is formed between the inner side wall of the upper cover and the axial pressure loading plunger and the extension portion; the axial pressure loading cavity is formed between the top wall of the upper cover and the axial pressure loading plunger; a seal is provided between the inner side wall of the upper cover and the axial pressure loading plunger, and the seal is located between the axial pressure loading cavity and the cooling cavity; a fifth channel and a sixth channel connected to the cooling cavity are provided on the upper cover or the axial pressure loading plunger.

[0020] Preferably, the core injection-production coupling experimental device further comprises:

[0021] The external circulation cooling system includes a driving pump connected to the fifth channel, and the driving pump is used to input cooling liquid into the cooling cavity.

[0022] Preferably, the tube body is made of copper.

[0023] Preferably, the first sealing ring is made of graphite, and the second sealing ring is made of graphite.

[0024] Preferably, a plurality of coaxially arranged annular grooves are formed on the end surface of the axial pressure loading plunger in contact with the core, and adjacent annular grooves are connected by radial grooves.

[0025] Preferably, an acoustic wave probe guide rod or a strain gauge is provided on the end surface of the axial pressure loading plunger in contact with the core.

[0026] A core injection-production coupling experimental method using any of the above core injection-production coupling experimental devices, the experimental method comprising:

[0027] Processing the core includes applying sealant to the side wall of the core and wrapping it with raw tape, covering the core and the axial pressure loading plunger and the axial pressure bearing plunger mechanism with a silicone sleeve, and then applying sealant between the silicone sleeve and the axial pressure loading plunger and the axial pressure bearing plunger mechanism, and loading the core into a core holder after the processing is completed;

[0028] After the core is loaded, the axial pressure is first applied through the axial pressure generating unit, and then the confining pressure is applied through the confining pressure generating unit;

[0029] Inputting coolant into the cooling chamber;

[0030] The core is heated to a set temperature by a heating furnace wrapped around the barrel so that the first sealing ring and the second sealing ring expand in the radial direction to ensure that the barrel and the core are fully sealed, and then the temperature is kept to ensure that the core reaches thermal equilibrium;

[0031] After thermal equilibrium is reached, fluid is pumped into the first channel through the liquid injection unit, and fluid flowing out of the third channel is recovered through the liquid recovery unit.

[0032] The technical solution of the present invention has the following significant beneficial effects:

[0033] 1. The present application provides a first sealing assembly between the tube body and the inner side wall of the housing mechanism to seal one end of the confining pressure loading chamber. The first sealing assembly includes a first retaining ring, a first sealing pressure ring, and a first sealing ring, the upper end of which abuts against the housing mechanism. The first sealing ring is located between the first retaining ring and the first sealing pressure ring. Through the above structure, the tube body, the core, and the axial pressure loading plunger can still be sealed under high temperature and high pressure. Moreover, the higher the temperature and pressure, the better the sealing performance. Regardless of changes in axial pressure or confining pressure, dynamic sealing can be achieved between the tube body, the core, and the axial pressure loading plunger, fully meeting the needs of high-temperature rock seepage experiments under different ground stress conditions.

[0034] 2. This application inputs coolant into the cooling chamber during the experiment. Since the axial pressure loading plunger of the clamp is affected by heat conduction when the core is heated, the temperature is often higher than the set temperature of the injected fluid. This phenomenon affects the accuracy of the experiment on the one hand, and reduces the temperature difference between the fluid and the core on the other hand, and the adjustable range of parameters will be greatly reduced. After continuously inputting coolant into the cooling chamber, the temperature of the cooling chamber of the axial pressure loading plunger decreases, and the amount of heat absorbed by the fluid injected by the liquid injection unit before reaching the core end face decreases, and the adjustable range of the injected fluid temperature increases. Compared with existing devices, this device can prevent the injected fluid from being heated by the high-temperature axial pressure loading plunger before reaching the core end face, thereby achieving adjustment of the injected fluid temperature within a larger range and increasing the injection-production temperature difference. The maximum temperature difference between the injected fluid and the core using this device can reach over 100°C.

[0035] With reference to the following description and drawings, specific embodiments of the present invention are disclosed in detail, indicating how the principles of the present invention can be employed. It should be understood that the embodiments of the present invention are not limited in scope thereby. Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the various components in the drawings are merely illustrative and are used to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the various components of the present invention. Those skilled in the art can select various possible shapes and proportional dimensions to implement the present invention according to specific circumstances under the guidance of the present invention.

[0037] Figure 1 This is a system principle diagram of the core injection-production coupling experimental device in an embodiment of the present invention;

[0038] Figure 2This is an external front view of a core holder according to an embodiment of the present invention;

[0039] Figure 3 A top view of a core holder according to an embodiment of the present invention;

[0040] Figure 4 A bottom view of a core holder according to an embodiment of the present invention;

[0041] Figure 5 is a cross-sectional view of a core holder according to an embodiment of the present invention;

[0042] Figure 6 Schematic diagram of an annular groove on the end surface of an axial pressure loading plunger in an embodiment of the present invention;

[0043] Figure 7 is an enlarged schematic diagram of the second sealing ring in the second sealing assembly after being compressed and deformed in an embodiment of the present invention;

[0044] Figure 8 Schematic diagram of the changes in the temperature of the core inlet, outlet, and barrel as the experiment proceeds in an embodiment of the present invention.

[0045] Reference numerals in the above drawings:

[0046] 1. Core holder; 101. Axial pressure loading plunger; 1011. Annular groove; 1012. Radial groove; 1013. First channel; 102. Axial pressure bearing plunger mechanism; 1021. Third channel; 103. Tube; 104. First sealing assembly; 1041. First stop ring; 1042. First sealing pressure ring; 1043. First sealing ring; 105. Housing mechanism; 1051. First opening; 1052. Second opening; 1053. Upper cover; 1054. Axial pressure connecting cover; 1055. Upper casing; 1056. Cylinder; 1057. Lower cover; 1058. Lower casing; 106. Axial pressure loading chamber; 107. Core; 108. Confining pressure loading chamber; 109. Second sealing assembly; 1091. Second stop ring Ring; 1092, second sealing pressure ring; 1093, second sealing ring; 1010, cooling chamber; 2, heating mechanism; 3, confining pressure generating unit; 31, confining pressure pump; 32, first condenser; 33, first pressure sensor; 34, first opening and closing valve; 4, axial pressure generating unit; 41, axial pressure pump; 42, second pressure sensor; 43, second opening and closing valve; 5, liquid injection unit; 51, container; 52, horizontal flow pump; 53, third opening and closing valve; 54, fourth opening and closing valve; 55, third pressure sensor; 6, liquid recovery unit; 61, recovery container; 62, back pressure device; 63, second condenser; 64, fourth pressure sensor; 7, first temperature sensor; 8, second temperature sensor; 9, control unit; 10, grating displacement meter. DETAILED DESCRIPTION

[0047] The details of the present invention can be more clearly understood in conjunction with the accompanying drawings and the description of the specific embodiments of the present invention. However, the specific embodiments of the present invention described herein are for illustrative purposes only and are not to be construed as limiting the present invention in any way. Based on the teachings of the present invention, skilled artisans can conceive of any possible variations based on the present invention, all of which should be considered within the scope of the present invention. It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can be an intermediate element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there can be an intermediate element. The terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, internal communication between two elements, direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms based on the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are intended only to describe specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0049] In order to solve the sealing problem of the core holder 1 under the change of axial pressure and confining pressure under high temperature conditions, and thus complete the indoor efficient simulation test research of the flow-heat transfer-deformation-chemical substance migration process, a core injection-production coupling experimental device is proposed in this application. Figure 1 This is a system principle diagram of the core injection-production coupling experimental device in an embodiment of the present invention. Figure 2 This is an external front view of the core holder in an embodiment of the present invention. Figure 3 : is a top view of the core holder in an embodiment of the present invention, Figure 4 This is a bottom view of the core holder in an embodiment of the present invention. Figure 5 FIG. 1 is a cross-sectional view of a core holder according to an embodiment of the present invention. Figures 1 to 5 As shown, the core injection-production coupling experimental device may include: a core clamp 1, which includes a shell mechanism 105, an axial pressure loading plunger 101, an axial pressure bearing plunger mechanism 102, a first sealing assembly 104, and a tube body 103; a heating mechanism 2; a confining pressure generating unit 3; an axial pressure generating unit 4; a liquid injection unit 5; and a liquid recovery unit 6.

[0050] Among them, such as Figure 1 、 Figure 2 、 Figure 3 and Figure 5 As shown, the upper end surface of the housing mechanism 105 may have a first opening 1051, and the lower end surface of the housing mechanism 105 may have a second opening 1052. At least a portion of the axial pressure loading plunger 101 is disposed within the housing mechanism 105, and at least a portion of the axial pressure loading plunger 101 extends through the first opening 1051. An axial pressure loading chamber 106 is formed between the axial pressure loading plunger 101 and the housing mechanism 105, enabling axial pressure loading plunger 101 to move axially. When hydraulic fluid is injected into the axial pressure loading chamber 106, the chamber 106 expands, causing the axial pressure loading plunger 101 to move downward, thereby achieving rigid loading on the end surface of the core 107.

[0051] like Figure 1 、 Figure 4 and Figure 5 As shown, at least a portion of the axial pressure bearing plunger mechanism 102 is disposed within the housing mechanism 105 and at least a portion of the axial pressure bearing plunger mechanism 102 extends through the second opening 1052. A core 107 is loaded between the axial pressure loading plunger 101 and the axial pressure bearing plunger mechanism 102. The axial pressure bearing plunger mechanism 102 is configured to support the core 107. The core 107 is generally cylindrical.

[0052] like Figure 5 As shown, the tubular body 103 is sleeved over the core 107, the axial pressure loading plunger 101, and the axial pressure bearing plunger mechanism 102. A confining pressure loading chamber 108 is formed between the outer wall of the tubular body 103 and the housing mechanism 105. When hydraulic fluid is injected into the confining pressure loading chamber 108, the pressure in the confining pressure loading chamber 108 increases. The confining pressure acts on the tubular body 103 to form a confining pressure on the core 107. The hydraulic fluid can be high-temperature resistant thermally conductive silicone oil to facilitate heat transfer, thereby heating the core 107. The tubular body 103 wraps and limits the circumferential surface of the core 107, and applies the confining pressure to the circumferential surface of the core 107.

[0053] like Figure 5As shown, the first sealing assembly 104 can be positioned between the tubular body 103 and the inner sidewall of the housing 105 to seal one end of the confining pressure loading chamber 108. The first sealing assembly 104 can include a first retaining ring 1041, whose upper end abuts the housing 105, a first sealing pressure ring 1042, and a first sealing ring 1043. The first sealing ring 1043 is positioned between the first retaining ring 1041 and the first sealing pressure ring 1042. Under pressure, the first sealing pressure ring 1042 can compress the first sealing ring 1043, causing it to expand radially. At least a portion of the first sealing ring 1043 is positioned corresponding to the lowest end of the axial pressure loading plunger 101, and at least a portion of the first sealing ring 1043 is positioned corresponding to the highest end of the core 107. This structure improves the sealing performance between the tubular body 103 and the axial pressure loading plunger 101, and between the tubular body 103 and the core 107.

[0054] Furthermore, one of the lower end face of the first stop ring 1041 and the upper end face of the first sealing pressure ring 1042 has a V-shaped protrusion, and the other has a corresponding V-shaped recess. When the first sealing pressure ring 1042 can compress the first sealing ring 1043 under pressure, the two sides of the first sealing ring 1043 can better extend and expand in the radial direction under the guidance of the V-shaped structure, so that the tube body 103 is closer to the core 107 and the axial pressure loading plunger 101.

[0055] like Figure 5 As shown, the axial pressure loading plunger 101 is provided with a first channel 1013 that is in communication with the upper end surface of the core 107. The axial pressure loading plunger 101 or the housing mechanism 105 is provided with a second channel that is in communication with the axial pressure loading chamber 106. The axial pressure bearing plunger mechanism 102 is provided with a third channel 1021 that is in communication with the lower end surface of the core 107. The housing mechanism 105 is provided with a fourth channel that is in communication with the confining pressure loading chamber 108.

[0056] like Figure 1As shown, the heating mechanism 2 is used to heat the core 107. The heating mechanism 2 can include a heating furnace wrapped around the barrel 1056. The heating furnace uses a stainless steel shell and is embedded with aluminum silicate ceramic fiber insulation cotton, which is environmentally friendly and non-toxic. The interior of the heating furnace is a ceramic liner with a thickness of more than 60 mm, in which the heating wire is distributed, which is not exposed to air, greatly improving the service life of the heating wire. In addition, the extremely thick liner can also stabilize the temperature of the central core 107 sample, ensuring that it is not affected by ambient temperature changes and improving the accuracy of the test. The core holder 1 can also be equipped with an insulation system on the periphery to maintain a constant temperature environment for the core holder 1 as a whole. The temperature is then transferred to the core 107 through the confining pressure medium. Multiple temperature sensors can be installed from the heating mechanism 2, the temperature control system, the core holder 1, and then to the core 107 installation location to simultaneously monitor and record temperature changes at different locations of the device, so as to dynamically adjust and control the core 107 to conduct the test at the predetermined temperature.

[0057] When the heating mechanism 2 heats the confining pressure loading chamber 108, the confining pressure in the confining pressure loading chamber 108 changes, and the temperature of the hydraulic fluid in the confining pressure loading chamber 108 rises, causing it to expand further. The higher the temperature, the greater the expansion, and thus the greater the pressure on the first sealing pressure ring 1042 and the second sealing pressure ring 1092. The first sealing pressure ring 1042 and the second sealing pressure ring 1092 compress the first sealing ring 1043 and the second sealing ring 1093 more strongly under the action of pressure, so that the first sealing ring 1043 and the second sealing ring 1093 expand more strongly in the radial direction, and the tighter the pressure between the tube body 103 and the core 107 and the axial pressure loading plunger 101, the better the sealing performance. Through the above structure, it can be ensured that the core clamp 1 can still maintain good sealing performance when conducting experiments at higher temperatures.

[0058] like Figure 1 As shown, the confining pressure generating unit 3 is used to generate confining pressure and is connected to the fourth channel. The confining pressure generating unit 3 may include: a confining pressure pump 31; a first condenser 32 connected to the outlet of the confining pressure pump 31; a first pressure sensor 33 for detecting the pressure at the outlet of the confining pressure pump 31; and a first on-off valve 34, one end of which is connected to the outlet of the confining pressure pump 31 and the other end is connected to the outside world. The first condenser 32 prevents high-temperature fluid from damaging the first on-off valve 34.

[0059] like Figure 1 As shown, the axial pressure generating unit 4 is used to generate axial pressure and is connected to the second channel. The axial pressure generating unit 4 may include: an axial pressure pump 41 connected to the second channel; a second pressure sensor 42 for detecting the pressure at the outlet of the axial pressure pump 41; and a second on-off valve 43, one end of which is connected to the outlet of the axial pressure pump 41 and the other end is connected to the outside world.

[0060] like Figure 1 As shown, the liquid injection unit 5 is connected to the first channel 1013. The liquid injection unit 5 includes: a container 51, which can be placed on an electronic balance to measure the weight of the container 51 and the fluid inside; a horizontal flow pump 52, whose inlet is connected to the container 51 and whose outlet is connected to the first channel 1013 via a third on-off valve 53. A fourth on-off valve 54 can be connected between the outlet of the horizontal flow pump 52 and the third on-off valve 53, with the other end of the fourth on-off valve 54 connected to the outside world; and a third pressure sensor 55 for detecting the pressure of the fluid flowing into the inlet of the first channel 1013. The core injection-production coupling experimental device can also include: a first temperature sensor 7 for measuring the temperature of the fluid flowing into the inlet of the first channel 1013.

[0061] like Figure 1 As shown, the liquid recovery unit 6 is connected to the third channel 1021. The liquid recovery unit 6 includes: a recovery container 61, which can be placed on an electronic balance to measure the weight of the recovery container 61 and the fluid inside; a back pressure device 62; a second condenser 63; and a fourth pressure sensor 64. The recovery container 61 is connected to the third channel 1021 via the back pressure device 62 and the second condenser 63 in sequence. The fourth pressure sensor 64 is used to detect the pressure of the fluid flowing out of the third channel 1021. The core injection-production coupling experimental device can include: a second temperature sensor 8, which is used to measure the temperature of the fluid at the inlet of the third channel 1021.

[0062] In the process, the liquid injection unit 5 is used for liquid injection, while the downstream liquid recovery unit 6 uses the second condenser 63 and the back pressure device 62 for outlet control. The liquid is measured by the electronic balance of the liquid injection unit 5 and the liquid recovery unit 6, and the data is recorded in the data collection system.

[0063] like Figure 4As shown, the housing mechanism 105 may include: an upper cover 1053 having a first opening 1051, an axial pressure connection cover 1054, a cylinder 1056, and a lower cover 1057. The inner side wall of the upper end of the axial pressure connection cover 1054 is connected to the outer side wall of the lower end of the upper cover 1053 by a thread. The inner side wall of the axial pressure connection cover 1054 has an extension portion extending radially, and the extension portion is annular and can extend to the side wall of the axial pressure loading plunger 101. The upper end of the tube body 103 is provided with an upper sleeve 1055 that is sleeved on the axial pressure loading plunger 101. The upper sleeve 1055 has a first outer edge, and the first outer edge abuts against the extension portion. The end face of the lower end of the upper sleeve 1055 abuts against the end face of the upper end of the tube body 103, and the wall thickness of the lower end of the upper sleeve 1055 is the same as that of the upper end of the tube body 103. The inner side wall of the first stop ring 1041 can cover the abutment between the lower end of the upper sleeve 1055 and the upper end of the tube body 103. The inner side wall of the first stop ring 1041 abuts the upper end of the upper sleeve 1055 and the tube body 103. The outer side wall of the upper end of the cylinder 1056 is connected to the inner side wall of the lower end of the axial pressure connection cover 1054 by a thread. The inner side wall of the lower cover 1057 is connected to the outer side wall of the lower end of the cylinder 1056 by a thread. The lower cover 1057 has a second opening 1052, and the axial pressure bearing plunger mechanism 102 is arranged in the second opening 1052. A lower retaining ring is fixedly arranged between the axial pressure bearing plunger mechanism 102 and the lower cover 1057, and the lower retaining ring abuts the step on the side wall of the axial pressure bearing plunger mechanism 102. Through the above structure, the upper sleeve 1055 can be positioned in the axial direction. At the same time, when the first sealing ring 1043 expands in the radial direction, the upper end of the tube body 103 can be used to better seal the contact between the core 107 and the axial pressure loading plunger 101.

[0064] Likewise, Figure 7 FIG. 1 is an enlarged schematic diagram of the second sealing ring in the second sealing assembly after being compressed and deformed in an embodiment of the present invention. Figure 4 and Figure 7 As shown, the core injection-production coupling experimental device may include a second sealing assembly 109, which is located between the tubular body 103 and the inner sidewall of the housing mechanism 105 to seal the other end of the confining pressure loading chamber 108. The second sealing assembly 109 includes a second retaining ring 1091, whose lower end abuts the lower cover 1057, a second sealing pressure ring 1092, and a second sealing ring 1093. The second sealing ring 1093 is located between the second retaining ring 1091 and the second sealing pressure ring 1092. Under pressure, the second sealing pressure ring 1092 can compress the second sealing ring 1093, causing it to expand radially. At least a portion of the second sealing ring 1093 corresponds to the uppermost end of the axial pressure bearing plunger mechanism 102. At least a portion of the second sealing ring 1093 corresponds to the lowermost end of the core 107.

[0065] Further, such as Figure 7 As shown, one of the upper end surface of the second retaining ring 1091 and the lower end surface of the second sealing pressure ring 1092 has a V-shaped protrusion, and the other has a corresponding V-shaped recess.

[0066] like Figure 5 and Figure 7 As shown, the lower end of the tube body 103 is provided with a lower sleeve 1058 that is sleeved on the axial pressure bearing plunger mechanism 102. The lower sleeve 1058 has a second outer edge that abuts against the axial pressure bearing plunger mechanism 102, thereby limiting the axial position of the lower sleeve 1058. The inner sidewall of the second stop ring 1091 abuts against the lower sleeve 1058 and the lowest end of the tube body 103. The upper end face of the lower sleeve 1058 abuts against the lower end face of the tube body 103. The upper end of the lower sleeve 1058 and the lower end of the tube body 103 have the same wall thickness. The inner sidewall of the second stop ring 1091 can cover the abutment between the upper end of the lower sleeve 1058 and the lower end of the tube body 103. The inner sidewall of the second stop ring 1091 abuts against the lower sleeve 1058 and the lowest end of the tube body 103.

[0067] When the axial pressure changes, the deformed first and second sealing rings 1043 and 1093 at the upper and lower ends of the core holder 1 close the gaps between the axial pressure-loading plunger 101 and the tubular body 103, as well as the gaps between the axial pressure-bearing plunger mechanism 102 and the tubular body 103, thereby ensuring a fluid seal under dynamic pressure. Compared to existing instruments that only vary the confining pressure, this technology enables flow testing under varying axial pressure, fully meeting the needs of high-temperature rock seepage experiments under varying in-situ stress conditions and providing more realistic and comprehensive physical modeling conditions.

[0068] As a feasible option, the tube body 103 can be made of copper, which has a certain toughness and deformation capacity. When the first sealing ring 1043 and the second sealing ring 1093 expand in the radial direction, the tube body 103 can deform to fit closely against the core 107 and the axial pressure loading plunger 101, thereby ensuring sealing. The first sealing ring 1043 is made of graphite, and the second sealing ring 1093 is made of graphite. They can be used at high temperatures, such as 400°C (or even 500°C to 600°C) and can operate stably for a long time. When the simulated environment has a formation temperature of 250 degrees or above, the first sealing ring 1043 and the second sealing ring 1093 will not fail or experience a decrease in sealing performance.

[0069] As feasible, Figure 5As shown, a cooling chamber 1010 is formed between the inner sidewall of the upper cover 1053 and the axial pressure loading plunger 101 and the extension. An axial pressure loading chamber 106 is formed between the top wall of the upper cover 1053 and the axial pressure loading plunger 101. A seal is provided between the inner sidewall of the upper cover 1053 and the axial pressure loading plunger 101 to prevent leakage between the cooling chamber 1010 and the axial pressure loading chamber 106. The seal is located between the axial pressure loading chamber 106 and the cooling chamber 1010. A fifth channel and a sixth channel are provided on the upper cover 1053 or the axial pressure loading plunger 101, communicating with the cooling chamber 1010.

[0070] Furthermore, the core injection-production coupling experimental apparatus can include an external cooling system comprising a drive pump connected to the fifth channel, which is used to supply coolant to the cooling chamber 1010. The coolant in the cooling chamber 1010 exchanges heat with the axial pressure loading plunger 101 before being discharged through the sixth channel. This approach reduces the temperature of the axial pressure loading plunger 101, allowing the fluid injected into the first channel 1013 by the liquid injection unit 5 to enter the core 107 at a lower temperature.

[0071] Figure 6 FIG. 1 is a schematic diagram of an annular groove on the end face of the axial pressure loading plunger in an embodiment of the present invention. Figure 6 As shown, the end surface of the axial compression loading plunger 101 in contact with the core 107 can be provided with multiple coaxially arranged annular grooves 1011, with adjacent annular grooves 1011 interconnected by radial grooves 1012. This structure ensures that the test medium flowing through has a larger contact area with the core 107, resulting in a more uniform distribution of the test medium. Since high-temperature rock fracture seepage experiments generally assume that the seepage velocity at each point on the end surface of the core 107 is similar, the presence of annular grooves 1011 prevents the injected fluid from spreading from a single point, better meeting the boundary conditions required by the experiment.

[0072] Furthermore, the end face of the axial compression loading plunger 101 in contact with the core 107 can be equipped with an acoustic probe guide rod or a strain gauge. Both can be installed according to experimental needs. The acoustic probe guide rod can be used for performing acoustic wave transit time measurements and extracting acoustic emission signals. The end face of the plunger can reserve deformation space for strain gauges, allowing them to be attached to the core 107 to monitor rock microstrain under high temperature and high pressure conditions.

[0073] The core injection-production coupling experimental device can include a control unit 9, which utilizes an industrial computer as its core and, in conjunction with pressure and temperature monitoring sensors, efficiently performs data acquisition, information transmission, real-time display, and storage. Uniaxial compression, load, strain, and other data in the system are transmitted to the computer in real time via ADAM digital-to-analog conversion. Windows-based application software can automatically record and process this data on the computer. The data acquisition board can be composed of a data acquisition and control module equipped with independently developed computer data acquisition peripheral circuitry. The heating furnace utilizes a temperature controller and precision platinum resistance temperature sensors for data acquisition and control, achieving a measurement and control accuracy of ±0.5°C within the temperature range of room temperature to 350°C. The efficient insulation of the heating furnace allows for accurate temperature stabilization to complete long-term seepage constant-temperature testing.

[0074] like Figure 1 As shown, a displacement test end face can be reserved on the end face of the upper end of the axial pressure loading plunger 101. The displacement test end face can be installed with a precision micrometer and a grating displacement meter 10 to monitor and record the movement of the axial pressure loading plunger 101, which is used to indicate the axial deformation of the core 107 in real time for reference by the test personnel.

[0075] Furthermore, a bursting assembly can be installed and connected to any pipeline in the confining pressure generating unit 3, the axial pressure generating unit 4, and the liquid injection unit 5. When the pressure in the pipeline exceeds the limit, the bursting disc in the bursting assembly will open under the pressure, thereby protecting downstream devices. The bursting assembly may include: a connector, a pressure ring, a bursting disc, and a clamping structure. The clamping structure has a fluid inlet and a fluid outlet, which are connected by a first channel 1013. The clamping structure also has a mounting hole for a release connector, in which a release connector is threadedly connected. The mounting hole is connected to the first channel 1013 via a second channel, and a bursting disc and a pressure ring are installed at the bottom of the mounting hole. The release connector has a third channel 1021 corresponding to the second channel. The release connector presses the pressure ring, which in turn presses the bursting disc. When the pressure in the first channel 1013 exceeds the set value of the bursting disc, the bursting disc ruptures, and the fluid in the first channel 1013 is released through the third channel 1021 of the release connector.

[0076] This application also proposes a core 107 injection-production coupling experimental method using any of the above core injection-production coupling experimental devices. The experimental method may include:

[0077] Core 107 is treated, including applying sealant to the sidewalls of core 107 and wrapping it with raw tape. A silicone sleeve is placed over core 107, the axial pressure loading plunger 101, and the axial pressure bearing plunger mechanism 102. Sealant is then applied between the silicone sleeve and the axial pressure loading plunger 101 and the axial pressure bearing plunger mechanism 102. After treatment, the core is placed in core holder 1. The diameter of the silicone sleeve can be slightly smaller than that of core 107. The sealant ensures that the fracturing fluid does not penetrate through the sidewalls of core 107 and does not pass through the interior of core 107.

[0078] After core 107 is loaded, axial pressure is first applied via axial pressure generating unit 4, followed by confining pressure via confining pressure generating unit 3. During the confining pressure application process, pressure is also applied to first and second sealing rings 1042, 1092, causing them to exert axial pressure on first and second sealing rings 1043, 1093, respectively, causing them to expand radially. The magnitude of the confining pressure can correspond to the reservoir in-situ stress, thereby simulating an actual reservoir.

[0079] Cooling liquid is input into the cooling chamber 1010 .

[0080] A heating furnace encasing the barrel 1056 heats the core 107 to a set temperature, causing the first and second sealing rings 1043 and 1093 to expand radially, ensuring a sufficient seal between the barrel 1056 and the core 107. This is then followed by insulation to ensure that the core 107 reaches thermal equilibrium. During this process, since coolant continuously flows into the cooling chamber 1010, the axial pressure loading plunger 101 can remain relatively cool, significantly cooler than the core 107. The higher the set temperature, the greater the radial expansion of the first and second sealing rings 1043 and 1093 after the core 107 is heated to the set temperature. This improves the sealing performance between the barrel 103 and the axial pressure loading plunger 101 and the axial pressure bearing plunger mechanism 102, and similarly improves the sealing performance between the barrel 103 and the upper end of the core 107.

[0081] After reaching thermal equilibrium, fluid is pumped into the first channel 1013 via the liquid injection unit 5, and the fluid flowing out of the third channel 1021 is recovered via the liquid recovery unit 6. The parameters of the pumped fluid correspond to the injection fluid flow rate designed in the experimental plan. During the experiment, various experimental data are collected and recorded. After the experiment is completed, pressure is released through the first on-off valve 34, the second on-off valve 43, etc.

[0082] This application differs from other existing high-temperature rock fracture seepage simulation processes in that it allows the injection of coolant into the cooling chamber 1010 during the experiment. As the core 107 heats up, the axial pressure loading plunger 101 in the holder is affected by heat conduction, often reaching a temperature higher than the set temperature of the injected fluid. This phenomenon not only affects the accuracy of the experiment, but also reduces the temperature difference between the fluid and the core 107, significantly narrowing the adjustable range of parameters. As coolant is continuously injected into the cooling chamber 1010, the temperature of the axial pressure loading plunger 101 decreases, reducing the amount of heat absorbed by the fluid injected by the liquid injection unit 5 before reaching the end of the core 107, thereby increasing the adjustable range of the injected fluid's temperature. Compared to existing devices, this device prevents the injected fluid from being heated by the high-temperature axial pressure loading plunger 101 before reaching the end of the core 107. This allows for a wider range of temperature adjustment for the injected fluid, increasing the injection-production temperature differential. Using this device, the maximum temperature difference between the injected fluid and the core 107 can reach over 100°C.

[0083] Figure 8 FIG. 1 is a schematic diagram showing changes in the temperature of the core inlet and outlet and the barrel 1056 as the experiment proceeds, as shown in FIG. Figure 8 As shown in Figure 2, the simulation environment in this example is a formation temperature of 250°C. Figure 8 As can be seen, the middle line represents the outlet temperature, the bottom line represents the inlet temperature, and the top line represents the wall temperature. Although the outer wall temperature of core 107 fluctuates slightly, it generally remains around 250°C. According to this data, after approximately four hours, the fluid and rock temperatures reach a stable state. At this point, the fluid temperature at the inlet of the upper end face of core 107 differs from the temperature of core 107 by approximately 100°C, and from the temperature at the outlet of core 107 by approximately 50°C. This core injection-production coupling experimental setup can widely vary the fluid temperature at the inlet of core 107, achieving a large injection-production temperature differential, facilitating experimental design and research. Due to the large temperature differential between the fluid and the rock sample, significant thermal damage occurs on the fracture surface. This core injection-production coupling experimental setup can also provide a basis for fracture damage models under injection-production conditions.

[0084] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for all purposes. The term "essentially consisting of..." describing a combination should include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel features of the combination. The use of the terms "comprising" or "including" to describe the combination of elements, ingredients, parts or steps herein also contemplates an embodiment that is essentially composed of these elements, ingredients, parts or steps. By using the term "may", it is intended to illustrate that any attribute described that "may" include is optional. Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0085] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A core injection-production coupling experimental device, characterized in that: The core injection-production coupling experimental device comprises: The core holder comprises a shell mechanism, an axial pressure loading plunger, an axial pressure bearing plunger mechanism, a first sealing assembly, and a tube body; the upper end face of the shell mechanism has a first opening, the lower end face of the shell mechanism has a second opening, at least part of the axial pressure loading plunger is arranged in the shell mechanism and at least part of the axial pressure loading plunger passes through the first opening, and an axial pressure loading cavity is formed between the axial pressure loading plunger and the shell mechanism, which enables the axial pressure loading plunger to move in the axial direction; at least part of the axial pressure bearing plunger mechanism is arranged in the shell mechanism and at least part of the axial pressure bearing plunger mechanism passes through the second opening; the core is loaded between the axial pressure loading plunger and the axial pressure bearing plunger mechanism; the tube body is sleeved outside the core, the axial pressure loading plunger and the axial pressure bearing plunger mechanism, and the outer side wall of the tube body is adjacent to the shell mechanism a first sealing ring and a second sealing ring are provided on the housing mechanism to seal the first sealing ring; the first sealing ring is located between the first sealing ring and the second sealing ring, and the first sealing ring is located between the first sealing ring and the first sealing ring; the first sealing ring is located between the first sealing ring and the first sealing ring, and the first sealing ring is compressed under pressure to expand the first sealing ring in the radial direction; the axial pressure loading plunger is provided with a first channel that can be communicated with the upper end face of the core, and the axial pressure loading plunger or the housing mechanism is provided with a second channel that is communicated with the axial pressure loading chamber; the axial pressure bearing plunger mechanism is provided with a third channel that can be communicated with the lower end face of the core, and the housing mechanism is provided with a fourth channel that is communicated with the confining pressure loading chamber; a heating mechanism for heating the core; a confining pressure generating unit for generating confining pressure, connected to the fourth channel; an axial pressure generating unit for generating axial pressure, connected to the second channel; a liquid injection unit connected to the first channel; A liquid recovery unit is connected to the third channel.

2. The core injection-production coupling experimental device according to claim 1, characterized in that: The housing structure comprises: The lockhole that is formed on the upper surface of the piston rod is formed on the upper surface of the piston rod and the lockhole engages with the piston rod of the piston rod at the bottom of the piston rod. The piston rod of the piston rod has a first end in contact with the piston rod of the piston rod. The piston rod of the piston rod has a first end in contact with the piston rod of the piston rod.

3. The core injection-production coupling experimental device according to claim 2, characterized in that: The core injection-production coupling experimental device also includes: a second sealing assembly, the second sealing assembly being located between the tube body and the inner sidewall of the housing mechanism to seal the other end of the confining pressure loading chamber, the second sealing assembly comprising a second retaining ring with a lower end resting against the lower cover, a second sealing pressure ring, and a second sealing ring, the second sealing ring being located between the second retaining ring and the second sealing pressure ring, and the second sealing pressure ring being able to compress the second sealing ring under pressure so as to expand the second sealing ring in the radial direction; The lower end of the tube body is provided with a lower sleeve body sleeved on the axial pressure bearing plunger mechanism, the lower sleeve body has a second outer edge, and the second outer edge abuts against the axial pressure bearing plunger mechanism; the inner side wall of the second stop ring abuts against the lower sleeve body and the lowermost end of the tube body; The heating mechanism includes a heating furnace wrapped around the cylinder.

4. The core injection-production coupling experimental device according to claim 2, characterized in that: A cooling cavity is formed between the inner side wall of the upper cover, the axial pressure loading plunger, and the extension portion; and the axial pressure loading cavity is formed between the top wall of the upper cover and the axial pressure loading plunger. A seal is provided between the inner side wall of the upper cover and the axial pressure loading plunger, and the seal is located between the axial pressure loading cavity and the cooling cavity; a fifth channel and a sixth channel connected to the cooling cavity are provided on the upper cover or the axial pressure loading plunger.

5. The core injection-production coupling experimental device according to claim 4, characterized in that: The core injection-production coupling experimental device also includes: The external circulation cooling system includes a driving pump connected to the fifth channel, and the driving pump is used to input cooling liquid into the cooling cavity.

6. The core injection-production coupling experimental device according to claim 1, characterized in that: The tube body is made of copper material.

7. The core injection-production coupling experimental device according to claim 3, characterized in that: The first sealing ring is made of graphite, and the second sealing ring is made of graphite.

8. The core injection-production coupling experimental device according to claim 1, characterized in that: A plurality of coaxially arranged annular grooves are provided on the end surface of the axial pressure loading plunger in contact with the core, and adjacent annular grooves are connected via radial grooves.

9. The core injection-production coupling experimental device according to claim 1, characterized in that: An acoustic wave probe guide rod or a strain gauge is provided on the end surface of the axial pressure loading plunger in contact with the core.

10. A core injection-production coupling experimental method using the core injection-production coupling experimental device according to any one of claims 4 to 9, characterized in that: The experimental method includes: Processing the core includes applying sealant to the side wall of the core and wrapping it with raw tape, covering the core and the axial pressure loading plunger and the axial pressure bearing plunger mechanism with a silicone sleeve, and then applying sealant between the silicone sleeve and the axial pressure loading plunger and the axial pressure bearing plunger mechanism, and loading the core into a core holder after the processing is completed; After the core is loaded, the axial pressure is first applied through the axial pressure generating unit, and then the confining pressure is applied through the confining pressure generating unit; Inputting coolant into the cooling chamber; The core is heated to a set temperature by a heating furnace wrapped outside the barrel so that the first sealing ring and the second sealing ring expand in the radial direction to ensure sufficient sealing between the barrel and the core, and then the temperature is kept to ensure that the core reaches thermal equilibrium; After thermal equilibrium is reached, fluid is pumped into the first channel through the liquid injection unit, and fluid flowing out of the third channel is recovered through the liquid recovery unit.

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