Method and device for measuring thermal conductivity in multiple directions under in-situ conversion condition of shale

Abstract

The invention provides a method and a device for measuring the thermal conductivity of shale in multiple directions under an in-situ conversion condition. The method comprises the following steps: acquiring a rock sample; putting the rock sample into a sample bin; applying triaxial pressure equivalent to stress under geological conditions to the rock sample through a triaxial pressurizing device; raising the temperature of the rock sample to the equilibrium temperature points through a constant-temperature heating device according to the set temperature raising condition and each equilibrium temperature point, and keeping the temperature constant; at each balance temperature point, inputting heat with preset instantaneous power to the hot lines through an energy output device, and collecting the change relation between the temperature rise value of each hot line and the heating time of the hot line in real time; according to the preset instantaneous power and the change relation between the temperature rise value of each hot line and the heating time of the hot line, the heat conductivity of the rock sample in the corresponding direction of each hot line under the shale in-situ conversion condition is obtained. According to the invention, the measurement of the thermal conductivity of the shale in any multiple directions under true triaxial pressure and any temperature can be realized, and the measurement precision is high.

Description

Technical Field

[0001] The invention relates to the field of petroleum exploration, and in particular to a method and a device for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale. Background Art

[0002] In view of the geological characteristics of China's shale, such as low maturity, large hydrocarbon generation potential, wide area distribution, multiple strata, and great resource potential, many scholars and institutions believe that foreign in-situ modification technology may be an effective way for China to achieve shale oil production. How to effectively evaluate the distribution of the thermal field during the in-situ heating and modification process has become the key to restricting the well site deployment and economic accounting of shale oil production. At present, the thermal field distribution is mainly simulated by large-scale thermal fluid-solid multi-field coupling software. However, the important parameter thermal conductivity in the simulation process is usually obtained using a normal temperature and pressure thermal conductivity tester, which not only ignores the influence of high temperature and high pressure on the thermal properties of rocks, but also ignores the influence of important fractures and generated fluids, which seriously affects the accuracy of constructing the thermal field, thereby affecting the evaluation of the economic feasibility of shale oil and causing economic losses to later field operations.

[0003] At present, the methods for thermal conductivity testing mainly include the conventional hot plate method, laser method and hot wire (surface source) method. These thermal conductivity testing methods are limited by temperature and pressure conditions, and cannot carry out high temperature and high pressure testing, let alone obtain thermal conductivity data in multiple directions at the same time. For example, the laser method cannot directly test thermal conductivity, and can only calculate thermal conductivity by combining thermal diffusion coefficient and specific heat, and the test pressure can only be normal pressure; the hot plate method can achieve high temperature and high pressure testing, but currently can only test thermal conductivity in one direction; and the conventional hot wire method is mainly concentrated in the liquid field. Summary of the invention

[0004] The embodiment of the present invention provides a method and device for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions, which are used to obtain the true triaxial pressure of shale and the thermal conductivity of shale in any multi-directional direction at any temperature with high measurement accuracy.

[0005] In a first aspect, the present application provides a method for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale, comprising:

[0006] Obtain rock samples; wherein the rock samples are obtained by: processing the collected mudstone samples into cubic rock samples, marking the directions of the rock samples, installing hot wires in each preset direction and filling with conductive glue to obtain the rock samples;

[0007] placing the rock sample into a sample chamber;

[0008] Applying triaxial pressure equivalent to the stress under geological conditions to the rock sample by a triaxial pressurizing device;

[0009] According to the set temperature increase conditions and each equilibrium temperature point, the rock sample is heated to the equilibrium temperature point by a constant temperature heating device and the temperature is kept constant;

[0010] At each equilibrium temperature point, heat of preset instantaneous power is input to the hot wire through the energy output device, and the relationship between the temperature rise value of each hot wire and the heating time of the hot wire is collected in real time;

[0011] According to the preset instantaneous power, the changing relationship between the temperature rise value of each hot line and the heating time of the hot line, the thermal conductivity of the rock sample along the corresponding direction of each hot line under the in-situ conversion condition of shale is obtained.

[0012] In one or some optional implementations of the embodiments of the present application, the relationship between the temperature rise value of each hot line and the heating time of the hot line according to the preset instantaneous power is used to obtain the thermal conductivity of the rock sample along the direction corresponding to each hot line under the in-situ conversion condition of shale, including:

[0013] For each of the hot lines, according to the preset instantaneous power, the relationship between the temperature rise value of the hot line and the heating time of the hot line, based on the following formula 1, the thermal conductivity of the rock sample along the corresponding direction of each hot line under the in-situ conversion condition of shale is calculated:

[0014]

[0015] Where: λ is the thermal conductivity, q is the preset instantaneous power of the hot wire, ΔT id is the temperature rise of the hot wire on the rock sample under ideal conditions, t is the heating time of the hot wire, a is the thermal diffusion coefficient of the hot wire, r0 is the radius of the hot wire, C (=1.781) is a constant, ΔT w is the measured temperature rise of the hot wire on the rock sample, δT i It is the correction of the temperature rise value of the hot wire under the ideal state by the actually measured temperature rise value of the hot wire.

[0016] In one or some optional implementations of the embodiments of the present application, the method for preparing the rock sample includes:

[0017] Collecting shale samples, and preparing the shale samples into cubic rock samples using a waterless wire cutting technique;

[0018] After marking the direction of the rock sample, observe and record the structure and bedding development characteristics of the rock sample;

[0019] Arranging the direction and quantity of the hot lines according to the bedding development characteristics of the rock sample, and carving hot line grooves on the surface of the rock sample according to the direction and quantity of the hot lines;

[0020] The heating wire is installed in the heating wire slot, and conductive glue is applied into the heating wire slot to fill the heating wire slot.

[0021] In one or some optional implementations of the embodiment of the present application, when the rock sample is placed in a sample chamber, each hot wire of the rock sample is connected to the energy output device respectively.

[0022] In one or some optional implementations of the embodiments of the present application, before applying a triaxial pressure equivalent to the stress under geological conditions to the rock sample through a triaxial pressurizing device, the three cylinders of the triaxial pressurizing device are respectively fixed to the top surface and two adjacent side surfaces of the sample bin.

[0023] In one or some optional implementations of the embodiments of the present application, the step of heating the rock sample to the equilibrium temperature point and maintaining the temperature constant by a constant temperature heating device according to the set heating conditions and the equilibrium temperature points includes:

[0024] According to the set heating conditions and each equilibrium temperature point, the rock sample is heated by a constant temperature heating device at a preset heating rate or a variable heating rate until the temperature reaches the equilibrium temperature point, and the temperature of the equilibrium temperature point is kept constant within a preset time.

[0025] In a second aspect, the present application provides a device for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale, comprising: a sample chamber, a triaxial pressurizing device, a constant temperature heating device, an energy output device, a data acquisition system and a data processing device;

[0026] The sample bin is used to place rock samples, wherein the rock samples are processed into cubic rock samples from collected mudstone samples, and after marking the directions of the rock samples, hot wires are installed in each preset direction and filled with conductive glue to obtain the rock samples;

[0027] The triaxial pressure device is respectively in contact with the top surface and two adjacent side surfaces of the rock sample, and is used to apply triaxial pressure equivalent to the stress under geological conditions to the rock sample;

[0028] The constant temperature heating device is arranged in the sample chamber, and is used to heat the rock sample to the equilibrium temperature point and keep the temperature constant;

[0029] The energy output device is connected to the hot wire and is used to input heat of preset instantaneous power to the hot wire;

[0030] A data acquisition system, used for real-time acquisition of the relationship between the temperature rise value of each hot wire and the heating time of the hot wire;

[0031] A data processing device is used to obtain the thermal conductivity of the rock sample along the corresponding direction of each hot line under the in-situ transformation condition of shale according to the preset instantaneous power, the temperature rise value of each hot line and the changing relationship between the heating time of the hot line.

[0032] In one or some optional implementations of the embodiment of the present application, a mounting hole detachably connected to the sample bin is provided on the outer side wall of the sample bin for placing the rock sample into the sample bin.

[0033] In one or some optional implementations of the embodiment of the present application, the triaxial pressurizing device includes three oil cylinders, three pistons and a hydraulic station, and each oil cylinder includes a cylinder head, a cylinder barrel and a piston connecting rod connected in sequence;

[0034] The three cylinder covers are connected to the top surface and two adjacent side surfaces of the sample chamber via annular flanges;

[0035] The three piston connecting rods extend into the sample chamber along the X direction, the Y direction and the Z direction respectively;

[0036] The three pistons are respectively connected to the three piston connecting rods and abut against the top surface and two adjacent side surfaces of the rock sample;

[0037] The three cylinders are connected to the hydraulic station via hydraulic oil pipes.

[0038] In one or some optional implementations of the embodiments of the present application, the constant temperature heating device includes a thermal element and a heating device;

[0039] The thermal element is arranged in the sample chamber, and the thermal element is connected to the heating device. The heating device is used to heat the thermal element, and is used to heat the rock sample to the equilibrium temperature point and keep the temperature constant.

[0040] In one or some optional implementations of the embodiments of the present application, the energy output device is a thermal conductor, and the thermal conductor is connected to the hot wire.

[0041] The beneficial effects of the above technical solution provided by the embodiment of the present application include at least:

[0042] The present invention provides a method for measuring the multi-directional thermal conductivity of mud shale under in-situ transformation conditions, wherein the collected mud shale samples are processed into cubic rock samples, the rock samples are marked in direction, hot wires are installed in each preset direction and filled with conductive glue to obtain rock samples, the rock samples are placed in a sample bin, a triaxial pressure equivalent to the stress under geological conditions is applied to the rock samples by a triaxial pressurizing device, the rock samples are heated to the equilibrium temperature point and the temperature is kept constant by a constant temperature heating device according to the set heating conditions and each equilibrium temperature point, at each equilibrium temperature point, heat of preset instantaneous power is input to the hot wire by an energy output device, and the relationship between the temperature rise value of each hot wire and the heating time of the hot wire is collected in real time, thereby obtaining the thermal conductivity of the rock sample in the corresponding direction of each hot wire under the in-situ transformation conditions of mud shale according to the preset instantaneous power and the relationship between the temperature rise value of each hot wire and the heating time of the hot wire. The present invention can realize the measurement of the thermal conductivity of mud shale in any multi-direction under true triaxial pressure and at any temperature, and the measurement accuracy is high. It fills the technical gap and provides key parameters for in-situ reforming, mining and numerical simulation of shale oil heating, which is of great significance to the petroleum industry.

[0043] Other features and advantages of the present application will be described in the subsequent description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings.

[0044] The technical solution of the present application is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0046] Figure 1 This is a flow chart of a method for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale in an embodiment of the present invention;

[0047] Figure 2 It is a schematic diagram of the hot line deployment section of the laminated shale for multi-directional thermal conductivity testing under the in-situ conversion conditions of shale in an embodiment of the present invention;

[0048] Figure 3 It is a schematic diagram of the hot wire deployment section of the multi-directional thermal conductivity test of the non-laminated mudstone under the in-situ conversion conditions of the mudstone in the embodiment of the present invention;

[0049] Figure 4 Schematic diagram of the structure of a multi-directional thermal conductivity measurement device under the condition of in-situ conversion of shale in an embodiment of the present invention;

[0050] Figure 5 It is a schematic diagram of the cross-sectional structure of a sample chamber of a multi-directional thermal conductivity measurement device under the condition of in-situ conversion of shale in an embodiment of the present invention;

[0051] Description of reference numerals:

[0052] 1 is a sample chamber, 2 is a triaxial pressurizing device, 3 is a constant temperature heating device, 4 is an energy output device, 5 is a data acquisition system, and 6 is a data processing device. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field before making creative work also fall within the scope of protection of the present invention.

[0054] It should be understood that, in the description of the embodiments of the present invention, all directional indication terms, such as "up", "down", "left", "right", "front", "back", etc., indicate the orientation or position relationship based on the orientation, position relationship shown in the drawings or the orientation or position relationship in which the invented product is usually placed when in use, which is only for the convenience of simplifying the description of the present invention, and does not expressly or imply that the device, element or component referred to must have a specific orientation and a specific orientation structure, and should not be understood as a limitation on the present invention. It is only used to explain the relative position relationship, movement, etc. between the components shown in the drawings. When the specific posture changes, the directional indication may also change accordingly.

[0055] In addition, ordinal numbers such as "first" and "second" in the present invention are only used for the purpose of distinction, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. The features defined as "first" and "second" can explicitly or implicitly indicate at least one of the technical features. In the description of the present invention, "multiple" means at least two, that is, two or more, unless otherwise clearly defined; "at least one" means one or one and more.

[0056] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, the positional relationship between components can be relatively fixed, or the components can be physically fixedly connected; they can be detachably connected or integrated; they can be mechanically connected or electrically connected; they can be directly connected or indirectly connected through an intermediate medium or component; they can be internally connected between two elements or interact with each other. Unless otherwise clearly defined in the specification, other interpretations may not achieve the corresponding functions or effects. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] The controller and control circuit involved in the present invention are conventional control technologies or units of those skilled in the art. For example, the control circuit of the controller can be realized by ordinary technicians in the field using existing technologies, such as simple programming. If the software or program involved in the control result is not described in detail, it belongs to the use of existing technologies or conventional technologies of ordinary technicians in the field. The power supply also uses the existing technologies in the field, and the main technical point of the present invention is to improve the mechanical device, so the present invention will not describe the specific circuit control relationship and circuit connection in detail.

[0058] The disclosure of the present invention provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described in the present invention. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0059] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0060] The inventors found that there are obvious method and technology gaps in sample grooving, wiring methods, reducing interface thermal resistance, high temperature of equipment, and triaxial pressure conditions for samples such as mud shale. In particular, for highly heterogeneous geological samples such as mud shale, they must also undergo in-situ transformation at high temperature and high pressure underground. Based on this, the inventors have further researched and developed a method and device for measuring multi-directional thermal conductivity under in-situ transformation conditions of shale.

[0061] Embodiment 1

[0062] See also Figure 1 The present application provides a method for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions, comprising:

[0063] Step S1, obtaining a rock sample; wherein the rock sample is obtained by the following method: processing the collected shale sample into a cubic rock sample, marking the direction of the rock sample, installing a hot wire in each preset direction and filling it with conductive glue to obtain the rock sample.

[0064] In this embodiment, the shale sample can be collected by a coring method. The coring method can be a conventional coring method or a pressure coring method, which is not limited here. The collected shale sample is a full-diameter core sample.

[0065] In this embodiment, the specific method for preparing the rock sample is: collect shale samples, and use waterless wire cutting technology to prepare the shale samples into cubic rock samples. The shape of the rock sample is preferably a cube with a length, height and width ranging from 45mm to 55mm. In actual application, the size of the rock sample can be adjusted according to actual needs. The rock sample can be polished by a polishing machine to make the surface of the rock sample smooth and flat. After marking the direction of the rock sample, observe and record the structure and bedding development characteristics of the rock sample. Arrange the direction and number of hot lines according to the bedding development characteristics of the rock sample.

[0066] Specifically, refer to Figure 2 As shown, for rock samples with developed bedding, hot wires need to be arranged in at least three directions: bedding direction, vertical bedding direction, and bedding oblique angle. Hot wire grooves are engraved on the surface of the rock sample using wire cutting technology according to the direction and number of hot wires. The width of the hot wire groove is preferably twice the diameter of the hot wire. When arranging the hot wire grooves, it should be ensured that each hot wire groove does not intersect and is located in the center of the rock sample. Install the hot wire in the hot wire groove, apply conductive glue to the hot wire groove and fill it up.

[0067] Similarly, refer to Figure 3 As shown, for rock samples with undeveloped bedding, hot wires are arranged in at least two directions, horizontally and vertically. Hot wire grooves are carved on the surface of the rock sample using wire cutting technology according to the direction and number of hot wires. When arranging hot wire grooves, it should be ensured that each hot wire groove does not intersect and is located in the center of the rock sample. Install the hot wire in the hot wire groove, apply conductive glue to the hot wire groove and fill it up.

[0068] In this embodiment, the hot wire is installed in the hot wire slot, and the hot wire slot is filled with high temperature and high pressure resistant conductive glue. The specific type of the conductive glue is not limited here, as long as the emulsification temperature of the conductive glue is higher than the temperature of the final equilibrium temperature point i. The conductive glue is applied to the hot wire slot and fills the hot wire slot to eliminate the interface thermal resistance.

[0069] Step S2: placing the rock sample into the sample chamber.

[0070] In this embodiment, when the rock sample is placed in the sample chamber, each hot wire on the rock sample is connected to the energy output device respectively.

[0071] Step S3: applying a triaxial pressure equivalent to the stress under geological conditions to the rock sample by a triaxial pressurizing device.

[0072] In this embodiment, before applying a triaxial pressure equivalent to the stress under geological conditions to the rock sample through the triaxial pressurizing device, the three oil cylinders of the triaxial pressurizing device are respectively fixed to the top surface and two adjacent side surfaces of the sample bin.

[0073] In this embodiment, the oil cylinder of the triaxial pressurizing device is driven to push the piston (or piston plate) to apply a triaxial pressure equivalent to the stress under geological conditions to the rock sample. The specific ground stress can be determined by regional information or geological data (average rock density × burial depth × gravity constant) to ensure that the rock sample meets the underground in-situ stress conditions of mud shale to restore the pressure environment of the actual formation, so that the multi-directional thermal conductivity obtained by subsequent calculation can better reflect the multi-directional thermal conductivity of the actual mud shale in the formation, and the calculation precision and accuracy are higher.

[0074] Step S4: According to the set heating conditions and each equilibrium temperature point i, the rock sample is heated to the equilibrium temperature point i by a constant temperature heating device and the temperature is kept constant.

[0075] In this embodiment, according to the set heating conditions and each equilibrium temperature point i, the rock sample is heated by a constant temperature heating device at a preset heating rate or a variable heating rate until the temperature reaches the equilibrium temperature point i, and the temperature of the equilibrium temperature point i is kept constant within a preset time.

[0076] Step S5: At each equilibrium temperature point i, heat of preset instantaneous power q is input to the hot wire through the energy output device, and the temperature rise value ΔT of each hot wire is collected in real time. w The relationship with the heating time t of the hot wire.

[0077] Step S6: According to the preset instantaneous power q, the temperature rise value ΔT of each hot wire w The relationship between the heating time t of the hot line and the thermal conductivity λ of the rock sample in the direction corresponding to each hot line under the in-situ transformation conditions of shale is obtained.

[0078] In a specific embodiment, according to the preset instantaneous power q, the temperature rise value ΔT of each hot wire is w The relationship between the heating time t of the hot line and the thermal conductivity λ of the rock sample along the corresponding direction of each hot line under the in-situ transformation condition of shale is calculated based on the following formula 1:

[0079]

[0080] Where λ is the thermal conductivity;

[0081] q is the preset instantaneous power of the hot wire;

[0082] ΔT id is the temperature rise of the hot wire on the rock sample under ideal conditions;

[0083] t is the heating time of the hot wire;

[0084] a is the thermal diffusion coefficient of the hot wire;

[0085] r0 is the radius of the hot line;

[0086] C(=1.781) is a constant;

[0087] ΔT w is the measured temperature rise of the hot wire on the rock sample;

[0088] δTi is the correction of the measured temperature rise of the hot wire to the temperature rise of the hot wire under ideal conditions.

[0089] In this embodiment, under theoretical conditions, at each equilibrium temperature point i, the energy output device inputs heat of preset instantaneous power q to the hot wire provided on the surface of the rock sample, and based on the theoretical formula of thermal conductivity, the thermal conductivity of each hot wire in the corresponding direction of the rock sample is calculated according to the relationship between the temperature rise value of each hot wire and the heating time of the hot wire, that is, the multi-directional thermal conductivity of the rock sample. However, in fact, there is a certain amount of heat loss in the heat transfer process of the hot wire, and there is a large error in directly using the theoretical formula of thermal conductivity to calculate the multi-directional thermal conductivity of the rock sample. Therefore, it is necessary to use a standard sample to obtain the heat loss in the heat transfer process, so as to correct the theoretical formula of thermal conductivity, thereby improving the measurement accuracy of the thermal conductivity of the rock sample. The standard sample is made of the same material using exactly the same process, that is, the standard sample is homogeneous, and its theoretical value of thermal conductivity at the test temperature point i is known. Therefore, the temperature rise value of the hot wire of the standard sample under an ideal state and a preset instantaneous power q (hereinafter referred to as the standard temperature rise value for ease of distinction) can be derived. The standard sample is placed in the sample compartment, and the above steps S4-S5 are executed to measure the temperature rise value of the hot wire of the standard sample at each equilibrium temperature point i and the preset instantaneous power q. The deviation between this value and the standard temperature rise value is the correction δTi of the temperature rise value of the hot wire.

[0090] Embodiment 2

[0091] See also Figure 4 and Figure 5 The present application provides a device for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions, comprising: a sample chamber 1, a triaxial pressurizing device 2, a constant temperature heating device 3, an energy output device 4, a data acquisition system 5 and a data processing device 6.

[0092] The sample bin 1 is used to place rock samples, wherein the rock samples are processed into cubic rock samples from the collected mudstone samples, and after the directions of the rock samples are marked, hot wires are installed in each preset direction and filled with conductive glue to obtain the rock samples;

[0093] The triaxial pressure device 2 is respectively in contact with the top surface and two adjacent side surfaces of the rock sample, and is used to apply triaxial pressure equivalent to the stress under geological conditions to the rock sample;

[0094] The constant temperature heating device 3 is arranged in the sample chamber 1, and is used to heat the rock sample to an equilibrium temperature point and keep the temperature constant;

[0095] The energy output device 4 is connected to the hot wire and is used to input heat of preset instantaneous power into the hot wire.

[0096] See also Figure 5 In a specific embodiment, a mounting hole (not shown in the figure) detachably connected to the sample bin 1 is provided on the outer wall of the sample bin 1, and is used to place the rock sample in the sample bin 1. Here, the shape of the mounting hole is not limited, and it can be circular, square or other shapes. The mounting hole is preferably detachable in a threaded or buckled manner to facilitate the installation or removal of the rock sample. An insulation layer can be provided on the outer wall of the sample bin 1, and the insulation layer is filled with insulation material to avoid excessive heat loss in the sample bin 1, thereby avoiding the use of the constant temperature heating device 3 to provide additional heat to compensate for the heat loss so that the sample bin 1 maintains a constant temperature at the equilibrium temperature point, which can save energy.

[0097] In a specific embodiment, see Figure 5 The three-axis pressurizing device 2 includes three oil cylinders, three pistons and a hydraulic station (not shown in the figure), and each oil cylinder includes a cylinder head, a cylinder barrel and a piston connecting rod connected in sequence.

[0098] Specifically, the three cylinder heads are connected to the top surface and two adjacent sides of the experimental chamber through annular flanges (not shown in the figure), the three piston connecting rods extend into the sample chamber 1 along the X direction, the Y direction and the Z direction respectively, the three pistons are connected to the three piston connecting rods respectively, the free ends of the three pistons are respectively in contact with the top surface and two adjacent sides of the rock sample, and the three cylinder barrels are provided with cylinder control ports, which connect the cylinder barrels to the hydraulic station through hydraulic oil pipes. When in use, the hydraulic station delivers pressure oil to the cylinder barrel through the hydraulic oil pipe, so that the piston connecting rod moves under the hydraulic pressure, thereby driving the piston to move in the direction of the rock sample, applying a triaxial pressure equivalent to the stress under geological conditions to the rock sample, and restoring the real formation conditions. A copper cooling water jacket can be set on each piston connecting rod. Each copper cooling water jacket is arranged between each cylinder head and the sample bin 1 and is pressed by each cylinder head through an annular flange. The copper cooling water jacket can prevent the sample bin 1 from deforming at high temperature and affecting the sealing between the sample bin 1 and the oil cylinder, thereby preventing the heat of the sample bin 1 from leaking out, so that the sample bin 1 has good thermal insulation. Since the constant temperature heating device 3 is required to keep the sample bin 1 at a constant equilibrium temperature point, the sample bin 1 has good thermal insulation, which saves energy.

[0099] In a specific embodiment, see Figure 5 The constant temperature heating device 3 includes a thermal element and a heating device (not shown in the figure). The thermal element is arranged in the sample bin 1, and the thermal element is connected to the heating device through a first opening (not shown in the figure) opened on the sample bin 1. The heating device is used to heat the thermal element, and is used to heat the rock sample to an equilibrium temperature point and keep the temperature constant. Among them, the first opening can be sealed with a high temperature resistant glue, and the high temperature resistant glue can be a heat-resistant epoxy glue, a phenolic resin glue, a silicone glue, etc. The type of high temperature resistant glue is not limited here, as long as it can achieve a good sealing effect, so as to ensure that the temperature of the sample bin 1 at the equilibrium temperature point is constant and avoid excessive heat loss. The heating device can be implemented by a conventional heating device or equipment, for example, it can be a high temperature heating furnace or a plasma torch.

[0100] In a specific embodiment, see Figure 4 The energy output device 4 is a thermal conductivity meter, which is connected to a hot wire (not shown in the figure) through a second opening (not shown in the figure) opened on the sample chamber 1, and is used to input heat of preset instantaneous power to the hot wire, and collect the temperature rise value of each hot wire and the change relationship of the heating time of the hot wire in real time. Among them, the second opening can be sealed with high temperature resistant glue, and its sealing method can adopt the sealing method of the first opening mentioned above.

[0101] In other embodiments, the energy output device 4 is a pulse heating device, which is connected to a hot wire (not shown in the figure) through a second opening (not shown in the figure) opened on the sample chamber 1, and is used to perform pulse heating on the hot wire and provide heat of a preset instantaneous power. Similarly, the second opening can be sealed according to the above-mentioned first opening, which is not repeated here.

[0102] In a specific embodiment, see Figure 4 The device for measuring the multi-directional thermal conductivity under the in-situ conversion conditions of shale also includes a data acquisition system 5 for collecting and recording the relationship between the temperature rise value of the hot wire and the heating time of the hot wire and the preset instantaneous power.

[0103] In a specific embodiment, see Figure 4 The device for measuring the multi-directional thermal conductivity under the in-situ transformation conditions of mudstone also includes a data processing device 6. The data processing device 6 is connected to the data acquisition system 5. The data processing device 6 receives the relationship between the temperature rise value of the hot line and the heating time of the hot line and the preset instantaneous power collected by the data acquisition system, and is used to calculate the thermal conductivity of the rock sample in the corresponding direction of each hot line along the hot line under the in-situ transformation conditions of mudstone according to the preset instantaneous power and the relationship between the temperature rise value of each hot line and the heating time of the hot line using Formula 1.

[0104] Those skilled in the art should understand that the embodiments of the present invention are described in detail above, and specific examples are used herein to describe the principles and implementation methods of the present invention in detail. It should be understood that the description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, those skilled in the art are not used to limit the scope of protection of the present invention based on the idea of ​​the present invention. Any modifications, equivalent substitutions, improvements, etc. made based on the specific implementation methods and application scope of the present invention within the spirit and principles of the present invention should be included in the scope of protection of the present invention. In summary, the content of this specification should not be understood as a limitation of the present invention.

Claims

1. A method for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale, characterized in that: include: Obtain rock samples; The rock sample is obtained by the following method: processing the collected mud shale sample into a cubic rock sample, marking the direction of the rock sample, installing a hot wire in each preset direction and filling it with conductive glue to obtain the rock sample; placing the rock sample into a sample chamber; Applying triaxial pressure equivalent to the stress under geological conditions to the rock sample by a triaxial pressurizing device; According to the set temperature increase conditions and each equilibrium temperature point, the rock sample is heated to the equilibrium temperature point by a constant temperature heating device and the temperature is kept constant; At each equilibrium temperature point, heat of preset instantaneous power is input to the hot wire through the energy output device, and the relationship between the temperature rise value of each hot wire and the heating time of the hot wire is collected in real time; According to the preset instantaneous power, the changing relationship between the temperature rise value of each hot line and the heating time of the hot line, the thermal conductivity of the rock sample along the corresponding direction of each hot line under the in-situ conversion condition of shale is obtained.

2. The method for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions according to claim 1, characterized in that: The thermal conductivity of the rock sample along the direction corresponding to each hot line under the in-situ transformation condition of shale is obtained based on the relationship between the temperature rise value of each hot line and the heating time of the hot line according to the preset instantaneous power, including: For each of the hot lines, according to the preset instantaneous power, the relationship between the temperature rise value of the hot line and the heating time of the hot line, based on the following formula 1, the thermal conductivity of the rock sample along the corresponding direction of each hot line under the in-situ conversion condition of shale is calculated: Where: λ is the thermal conductivity, q is the preset instantaneous power of the hot wire, ΔT id is the temperature rise of the hot wire on the rock sample under ideal conditions, t is the heating time of the hot wire, a is the thermal diffusion coefficient of the hot wire, r0 is the radius of the hot wire, C (=1.781) is a constant, ΔT w is the measured temperature rise of the hot wire on the rock sample, δT i It is the correction of the temperature rise value of the hot wire under the ideal state by the actually measured temperature rise value of the hot wire.

3. The method for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions according to claim 1, characterized in that: The method for preparing the rock sample comprises: Collecting shale samples, and preparing the shale samples into cubic rock samples using a waterless wire cutting technique; After marking the direction of the rock sample, observe and record the structure and bedding development characteristics of the rock sample; Arranging the direction and quantity of the hot lines according to the bedding development characteristics of the rock sample, and carving hot line grooves on the surface of the rock sample according to the direction and quantity of the hot lines; The heating wire is installed in the heating wire slot, and conductive glue is applied into the heating wire slot to fill the heating wire slot.

4. The method for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions according to claim 1, characterized in that: When the rock sample is placed in a sample chamber, each hot wire of the rock sample is connected to the energy output device respectively.

5. The method for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions according to claim 1, characterized in that: Before applying a triaxial pressure equivalent to the stress under geological conditions to the rock sample through a triaxial pressurizing device, three oil cylinders of the triaxial pressurizing device are respectively fixed to the top surface and two adjacent side surfaces of the sample bin.

6. The method for measuring multi-directional thermal conductivity of shale under in-situ conversion conditions according to claim 1, characterized in that: According to the set heating conditions and each equilibrium temperature point, the rock sample is heated to the equilibrium temperature point by a constant temperature heating device and the temperature is kept constant, including: According to the set heating conditions and each equilibrium temperature point, the rock sample is heated by a constant temperature heating device at a preset heating rate or a variable heating rate until the temperature reaches the equilibrium temperature point, and the temperature of the equilibrium temperature point is kept constant within a preset time.

7. A device for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale, characterized in that: include: Sample chamber, triaxial pressurizing device, constant temperature heating device, energy output device, data acquisition system and data processing device; The sample bin is used to place rock samples, wherein the rock samples are processed into cubic rock samples from collected mudstone samples, and after marking the directions of the rock samples, hot wires are installed in each preset direction and filled with conductive glue to obtain the rock samples; The triaxial pressure device is respectively in contact with the top surface and two adjacent side surfaces of the rock sample, and is used to apply triaxial pressure equivalent to the stress under geological conditions to the rock sample; The constant temperature heating device is arranged in the sample chamber, and is used to heat the rock sample to the equilibrium temperature point and keep the temperature constant; The energy output device is connected to the hot wire and is used to input heat of preset instantaneous power to the hot wire; A data acquisition system, used for real-time acquisition of the relationship between the temperature rise value of each hot wire and the heating time of the hot wire; A data processing device is used to obtain the thermal conductivity of the rock sample along the corresponding direction of each hot line under the in-situ transformation condition of shale according to the preset instantaneous power, the temperature rise value of each hot line and the changing relationship between the heating time of the hot line.

8. The device for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale according to claim 7, characterized in that: An installation hole detachably connected to the sample bin is provided on the outer side wall of the sample bin and is used for placing the rock sample into the sample bin.

9. The device for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale according to claim 8, characterized in that: The three-axis pressurizing device comprises three oil cylinders, three pistons and a hydraulic station, wherein each oil cylinder comprises a cylinder head, a cylinder barrel and a piston connecting rod connected in sequence; The three cylinder covers are connected to the top surface and two adjacent side surfaces of the sample chamber via annular flanges; The three piston connecting rods extend into the sample chamber along the X direction, the Y direction and the Z direction respectively; The three pistons are respectively connected to the three piston connecting rods and abut against the top surface and two adjacent side surfaces of the rock sample; The three cylinders are connected to the hydraulic station via hydraulic oil pipes.

10. The device for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale according to claim 9, characterized in that: The constant temperature heating device comprises a thermal element and a heating device; The thermal element is arranged in the sample chamber, and the thermal element is connected to the heating device, and the heating device is used to heat the thermal element, so as to heat the rock sample to the equilibrium temperature point and keep the temperature constant.

11. The device for measuring multi-directional thermal conductivity under in-situ conversion conditions of shale according to claim 10, characterized in that: The energy output device is a thermal conductivity meter, and the thermal conductivity meter is connected to the hot wire.

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