Method and device for testing dynamic thermal conductivity in shale sample in-situ conversion

Abstract

The invention provides a method for testing dynamic thermal conductivity in in-situ conversion of a shale sample, which comprises the following steps: processing a drilling core into a cylindrical rock sample, and measuring the size of the rock sample; obtaining a standard sample; mounting a rock sample in the sample chamber; an inert gas protection device is used for protection; axial pressure and confining pressure under the formation condition are applied to the rock sample through the pressure control device; raising the temperature of the rock sample to a test temperature point through a sample temperature control device, and keeping the temperature constant; continuously providing heat with constant power for the top plate through a heat source control device to obtain a temperature difference between the top plate and the bottom plate at each test temperature point; determining a heat conductivity test value according to the temperature difference and the constant power corresponding to each test temperature point of the standard sample, and determining a heat correction in combination with a heat conductivity theoretical value; and determining the rock sample thermal conductivity according to the data. By providing a test condition fitting the stratum environment for the rock sample and correcting the thermal conductivity calculation formula with the heat correction, the accuracy of the calculated thermal conductivity is higher.

Description

Technical Field

[0001] The invention relates to a testing technology for petroleum exploration, and in particular to a method and a device for testing the dynamic thermal conductivity of a shale sample in in-situ transformation. Background Art

[0002] The shale revolution has changed the world's energy and geopolitical landscape. In 2020, shale oil production exceeded 3.5×10 8 t, shale oil has become an important area for increasing oil reserves and production. According to different thermal maturity (Ro), shale oil is divided into two types: medium-high maturity (Ro>1.0%) and medium-low maturity (Ro≤1.0%). Medium-high maturity shale oil has been commercially developed, while medium-low maturity shale oil and oil shale cannot be commercially developed with existing horizontal well volume transformation technology due to low thermal maturity, low organic matter conversion rate, low gas-oil ratio, and undeveloped organic pores. However, in-situ conversion technology is effective and feasible. In-situ conversion is a technology that converts organic matter into light oil and gas and produces it by underground in-situ heating of medium-low maturity shale oil or oil shale. According to the author's estimate, the technically recoverable resources of medium-low maturity shale oil and oil shale resources in the world are 1.4×10 11 t and 6.6×10 11 t, is an important strategic successor area for the future growth of oil and gas reserves and production. The effective development and utilization of this type of resources will once again change the global oil and gas supply and geopolitical landscape.

[0003] Due to the cracking of organic matter in shale with temperature changes, the dynamic thermal field parameters change greatly. Therefore, the current thermophysical parameter testing technology based on the unchanged material composition cannot meet the needs of shale in-situ conversion thermal field modeling. The detailed description of the evolution of the temperature field during the heating process is conducive to the engineering design of heating well spacing and efficient heat transfer. However, since the dynamic thermal field parameters of shale will change greatly with temperature changes, the simulation results of shale thermal field deviate from reality. Although some scholars have proposed a test device for the thermal conductivity of shale samples under high temperature and high pressure conditions through transient surface source methods (invention patent: ZL 201810203414.2), the surface source method is based on the heat flow information on the rock surface and belongs to a transient test method, which is different from the steady-state method applied this time. In addition, although the transient method has the advantage of fast speed, its accuracy is slightly lower than that of the steady-state method. Although there are currently some correction methods based on the hot plate method in the steady-state method and the patents of high temperature and high pressure (invention patents: ZL201610848074.X; ZL20171 0095096.8), some scholars have proposed some correction methods (correction method of heat exchange power of thermal conductivity tester using single specimen protected hot plate method), but even if these experimental devices can meet certain high temperature and high pressure conditions, they still cannot meet the requirements of dynamic changes of shale under in-situ high temperature and high pressure and the test of rock volume heat flow under in-situ anoxic environment, and they do not provide the specific number and sampling requirements of dynamic thermal conductivity test samples suitable for in-situ transformation conditions. Summary of the invention

[0004] The main purpose of the embodiments of the present invention is to provide a method and device for testing the dynamic thermal conductivity during in-situ conversion of shale samples, thereby integrating dynamic high temperature and high pressure, inert gas protection, dual thermal protection of top and bottom plates, standard sample calibration, and sampling conditions to serve the dynamic thermal conductivity test during in-situ conversion of shale.

[0005] In a first aspect, an embodiment of the present invention provides a method for testing the dynamic thermal conductivity of a shale sample during in-situ conversion, comprising the following steps:

[0006] Processing the drill core of the in-situ conversion target area into a cylindrical rock sample, and measuring the size of the rock sample;

[0007] Obtain standard samples;

[0008] The following test steps are performed on the rock sample and the standard sample respectively:

[0009] Install the rock sample in the sample chamber;

[0010] Placing the sample chamber in a protection chamber, and filling the protection chamber with inert gas through an inert gas protection device;

[0011] applying axial pressure and confining pressure under formation conditions to the rock sample by a pressure control device;

[0012] According to the set heating conditions and each test temperature point, the rock sample is heated to the test temperature point by the sample temperature control device and the temperature of the temperature point is kept stable and balanced;

[0013] After the heat flux of the top plate and the bottom plate of the rock sample at each test temperature point is stabilized, a heat source control device is used to continuously provide constant power heat to the top plate, and the temperatures of the top plate and the bottom plate are detected in real time, and after stabilization, the temperature difference between the top plate and the bottom plate at each test temperature point is obtained;

[0014] Determine the thermal conductivity test value according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, and determine the heat correction amount at each test temperature point according to the thermal conductivity test value and the corresponding thermal conductivity theoretical value obtained;

[0015] The thermal conductivity of the rock sample at the corresponding test temperature point under in-situ conversion geological conditions is determined according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample and the heat correction amount at the corresponding test temperature point.

[0016] In one or some optional implementations of the embodiments of the present application, the thermal conductivity test value is determined according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, and the heat correction amount at each test temperature point is determined according to the thermal conductivity test value and the corresponding thermal conductivity theoretical value obtained, including:

[0017] Before adding the standard sample into the sample chamber, measuring the size of the standard sample, wherein the standard sample is a sample with a known theoretical value of thermal conductivity;

[0018] According to the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, the thermal conductivity test value is calculated by the following formula 1:

[0019]

[0020] Among them, λ 测i is the thermal conductivity test value of the standard sample measured at the test temperature point i; q is the power of the heat source control device; Δx1 is the height of the standard sample; ΔT 1i is the temperature difference between the top plate and the bottom plate of the standard sample at the test temperature point i;

[0021] According to the thermal conductivity test value and the corresponding thermal conductivity theoretical value obtained, the heat correction amount at each test temperature point is calculated by the following formula 2:

[0022]

[0023] Where Δqi is the heat correction at the test temperature point i; λ 标i is the theoretical value of thermal conductivity of the standard sample at the test temperature i; 测i is the thermal conductivity test value of the standard sample at the test temperature point i calculated according to formula 1; ΔT 1i is the temperature difference between the top plate and the bottom plate of the standard sample at the test temperature point i; Δx1 is the height of the standard sample.

[0024] In one or some optional implementations of the embodiments of the present application, determining the thermal conductivity of the rock sample at the corresponding test temperature point under the in-situ conversion geological conditions according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample, and the heat correction amount at the corresponding test temperature point, includes:

[0025] According to the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample, as well as the heat correction amount at the corresponding test temperature point, the thermal conductivity of the rock sample at the corresponding test temperature point under the in-situ conversion geological conditions is calculated by the following formula 3:

[0026]

[0027] Wherein, λi is the thermal conductivity of the rock sample at the test temperature point i under the in-situ conversion geological condition; q is the constant power of the heat source device; Δqi is the heat correction at the test temperature point i; Δx is the height of the rock sample; ΔT i is the temperature difference between the top and bottom plates of the rock sample at the test temperature point i.

[0028] In one or some optional implementations of the embodiments of the present application, processing the in-situ conversion target area drilling core into a cylindrical rock sample and measuring the size of the rock sample includes:

[0029] Using a waterless wire cutting technique to take a sample from a well core of an in-situ conversion target area, and processing the rock sample into a cylindrical shape using the waterless wire cutting technique, wherein the diameter of the rock sample is 2.5 cm to 4.0 cm and the height is 0.3 cm to 0.7 cm;

[0030] The dimensions of the rock sample were measured using a micrometer.

[0031] In one or some optional implementations of the embodiment of the present application, applying axial pressure and confining pressure under formation conditions to the rock sample by a pressure control device includes:

[0032] The pressure under formation conditions is applied to the rock sample in radial and axial directions respectively by the pressure control device, wherein the pressure applied by the pressure control device has a pressure range of 0 MPa to 100 MPa.

[0033] In one or some optional implementations of the embodiments of the present application, the temperature increase condition includes a preset temperature increase rate or a variable temperature increase rate;

[0034] According to the set heating conditions and each test temperature point, the rock sample is heated to the test temperature point by a sample temperature control device and the temperature of the temperature point is kept balanced and stable, including:

[0035] According to the set heating conditions and each test temperature point, the rock sample is heated by a sample temperature control device at a preset heating rate or a variable heating rate until the temperature reaches the test temperature point, and the temperature of the test temperature point is maintained at the temperature equilibrium point for a preset time length; wherein the test temperature points include 25°C, 100°C, 200°C, 300°C, 400, 500°C and 600°C.

[0036] In one or some optional implementations of the embodiments of the present application, further comprising:

[0037] When the rock sample is installed in the sample chamber, a heat preservation and insulation device is arranged on the outer wall of the sample chamber.

[0038] In a second aspect, the present application provides a dynamic thermal conductivity testing device for in-situ conversion of shale samples, comprising: a protection chamber, a sample chamber, an inert gas protection device, a heat source control device, a sample temperature control device, and a pressure control device;

[0039] The protection chamber is used to provide a closed environment;

[0040] The sample chamber is arranged in the protection chamber and is used to place rock samples, wherein the rock samples are cylindrical rock samples obtained by processing the core of the well in the in-situ conversion target area;

[0041] The inert gas protection device is connected to the protection chamber, provides inert gas to the protection chamber and replaces air, and is used to provide inert gas protection to the protection chamber;

[0042] The sample temperature control device is disposed in the sample chamber, and is used to control the temperature of the sample chamber to reach and maintain a preset temperature;

[0043] The heat source control device is connected to the top plate and the bottom plate of the rock sample respectively, and is used to provide constant power heat to the top plate and detect the temperature of the top plate and the bottom plate in real time;

[0044] The pressure control device acts on the rock sample in the axial and radial directions, and is used to apply axial pressure and confining pressure under formation conditions to the rock sample.

[0045] In one or some optional implementations of the embodiments of the present application, the inert gas protection device includes an inert gas source and a gas extraction device;

[0046] The inert gas source is connected to the protection chamber to provide inert gas;

[0047] The vacuum device is connected to the protection chamber for vacuuming.

[0048] In one or some optional implementations of the embodiment of the present application, the pressure control device includes three oil cylinders, three pistons and a hydraulic station, and each of the oil cylinders includes a cylinder head, a cylinder barrel and a piston connecting rod connected in sequence;

[0049] The three cylinder covers are connected to the top surface and two adjacent side surfaces of the sample chamber via annular flanges;

[0050] The three piston connecting rods extend into the sample chamber along the X direction, the Y direction and the Z direction respectively;

[0051] The three pistons are respectively connected to the three piston connecting rods and abut against the top surface and side surfaces of the rock sample;

[0052] The three cylinders are connected to the hydraulic station via hydraulic oil pipes.

[0053] In one or some optional implementations of the embodiment of the present application, the heat source control device includes a first thermal element and a first pulse heating device;

[0054] The top plate and the bottom plate of the rock sample are each provided with a first thermal element;

[0055] The first pulse heating device is connected to each of the first thermal elements through the wire openings opened on the protection chamber and the side walls of the sample chamber. The first pulse heating device is used to perform pulse heating treatment on the first thermal element. The wire openings are provided with high-temperature resistant sealant for sealing.

[0056] In one or some optional implementations of the embodiments of the present application, the sample temperature control device includes a temperature sensor, a second thermal element, and a second heating device;

[0057] The second thermal element is disposed in the sample chamber;

[0058] The second heating device is connected to the second thermal element, and the second heating device is used to heat the second thermal element;

[0059] The temperature sensor is disposed in the sample chamber and is used to detect the temperature of the sample chamber.

[0060] One or some optional implementations of the embodiments of the present application also include a heat source control calculation system, which is used to collect the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, as well as the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample, and the heat correction amount at the corresponding test temperature point, and determine the heat correction amount at each test temperature point based on the thermal conductivity test value of the standard sample and the corresponding thermal conductivity theoretical value obtained, and calculate the thermal conductivity of the rock sample at the corresponding test temperature point under in-situ conversion geological conditions.

[0061] One or some optional implementations of the embodiment of the present application further include a thermal insulation device, which includes a thermal insulation board and an insulation sleeve. The outer wall of the sample chamber is provided with an insulation board, and the insulation sleeve is sleeved on the thermal insulation board.

[0062] The beneficial effects of the above technical solution provided by the embodiment of the present application include at least:

[0063] The present application provides a method and device for testing the dynamic thermal conductivity of shale samples in situ transformation, which collects core samples on site in the oil field, applies axial pressure, confining pressure and temperature under the formation to the rock samples with a pressure control device and a sample temperature control device, and restores the real underground environment. At the same time, the protection chamber is protected by an inert gas protection device, so that the rock samples in the sample chamber are always in an inert gas environment, and the formation anoxic environment is restored. Since the rock samples and test conditions are as consistent as possible with the conditions of in situ transformation under the formation, the detection environment is closer to the real formation environment, and the measured thermal conductivity is more accurate. Then, dynamic high temperature and high pressure, inert gas protection, dual thermal protection of top and bottom plates, standard sample calibration, and sampling conditions are integrated to serve the dynamic thermal conductivity test in shale in situ transformation.

[0064] 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.

[0065] The technical solution of the present application is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. 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 paying creative labor.

[0067] Figure 1 This is a flow chart of a method for testing dynamic thermal conductivity during in-situ conversion of shale samples according to an embodiment of the present invention;

[0068] Figure 2 It is a connection schematic diagram of a dynamic thermal conductivity testing device in in-situ conversion of shale samples according to an embodiment of the present invention;

[0069] Figure 3 This is a structural diagram of a dynamic thermal conductivity testing device for in-situ conversion of shale samples according to an embodiment of the present invention;

[0070] Figure 4 This is a comparison diagram of the standard thermal conductivity of SiO2 and the standard sample tested by the dynamic thermal conductivity testing device in the in-situ conversion of shale samples according to an embodiment of the present invention;

[0071] Figure 5 This is an error diagram of the standard thermal conductivity of SiO2 and the standard sample tested by the dynamic thermal conductivity testing device in the in-situ conversion of shale samples according to an embodiment of the present invention;

[0072] Figure 6 The thermal conductivity calculation results of the Chang 7 shale sample in the Ordos Basin under dynamic temperature and pressure conditions in different directions are calculated using the corrected thermal conductivity formula;

[0073] Description of reference numerals:

[0074] 1 is the protection chamber; 2 is the sample chamber; 3 is the inert gas protection device; 4 is the heat source control device; 5 is the sample temperature control device; 6 is the pressure control device. DETAILED DESCRIPTION

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] Embodiment 1

[0083] Reference Figure 1 The present application provides a method for testing the dynamic thermal conductivity of a shale sample during in-situ conversion. The method mainly comprises the following steps:

[0084] S1. Process the drilling core of the in-situ conversion target area into a cylindrical rock sample and measure the size of the rock sample.

[0085] In this embodiment, a drilling core is obtained from a coring well in the in-situ conversion target area, a certain number of core samples are taken from the drilling core using a waterless wire cutting technique, and the core samples are processed into uniformly shaped rock samples using a waterless wire cutting technique, so that the surface of the rock sample is flat and smooth. The shape of the processed rock sample is preferably cylindrical, and its diameter range is preferably 2.5cm to 4.0cm, and the height range is preferably 0.3cm to 0.7cm. In actual application, the size of the rock sample can be adjusted according to actual needs. In order to further ensure the flatness of the rock sample surface, a rock polisher can be further used to grind the rock surface to achieve a better flatness. The size of the rock sample is accurately measured with a micrometer, including the height Δx of the rock sample. It is worth noting that the specific shape of the rock sample is not limited here, and it can be cylindrical, rectangular, square, etc., as long as its shape is uniform.

[0086] It is worth noting that the number of drilling cores corresponding to the target layer of each coring well is no less than 20. At least 2 core samples are taken in the horizontal and vertical directions at the target position of the drilling core, and the drilling fluid impregnation area on the core sample is cut off to avoid deviation in the thermal conductivity measurement results of subsequent rock samples.

[0087] S2. Obtain standard samples.

[0088] In this embodiment, the standard sample is a sample with a known theoretical value of thermal conductivity. Before the standard sample is added to the sample chamber, the size of the standard sample is accurately measured with a micrometer, including the height Δx1 of the standard sample. The specific type of the standard sample is not limited here, and a SiO2 standard sample can be used.

[0089] Then perform the following test steps on the rock sample and the standard sample respectively:

[0090] S3. Install the rock sample in the sample chamber.

[0091] In this embodiment, when the rock sample is installed in the sample chamber, thermal insulation devices are arranged at both ends of the top and bottom of the sample chamber.

[0092] S4. Place the sample chamber in a protective chamber and fill the protective chamber with inert gas through an inert gas protection device.

[0093] In this embodiment, an inert gas is filled into the protection chamber through an inert gas protection device, so that the subsequent rock sample is always in the inert gas during the thermal conductivity test, so as to restore the oxygen-deficient environment under the formation conditions, so that the detection environment is closer to the actual formation environment, so that the thermal conductivity measured subsequently is more consistent with the thermal conductivity under the actual formation environment, and its accuracy is higher. It is worth noting that the gas type of the inert gas is not limited here, and nitrogen or argon can be used, as long as it can provide an oxygen-deficient environment for the rock sample to restore the actual formation environment.

[0094] S5. Apply axial pressure and confining pressure under formation conditions to the rock sample through a pressure control device.

[0095] In this embodiment, the rock sample is pressurized by a pressure control device so that the axial pressure and radial pressure of the rock sample are at preset axial pressure values ​​and preset radial pressure values, the preset axial pressure value is 0MPa~100MPa, and the preset axial pressure value is 0MPa~100MPa. The specific value is determined according to the ground stress at the depth of the target layer where the rock sample is located, thereby restoring the formation pressure of the rock sample and matching it with the actual formation environment, so that the subsequently calculated thermal conductivity is more consistent with the thermal conductivity in the actual formation environment, and its accuracy is higher.

[0096] S6. According to the set heating conditions and each test temperature point i, the rock sample is heated to the test temperature point i by the sample temperature control device and the temperature of the temperature point is kept balanced and stable.

[0097] In this embodiment, according to the set heating conditions and each test temperature point i, the rock sample is heated by the sample temperature control device at a preset heating rate or a variable heating rate until the temperature reaches the test temperature point i, and the temperature of the test temperature point i is maintained at the temperature equilibrium point within a preset time; wherein the test temperature point i includes 25°C, 100°C, 200°C, 300°C, 400, 500°C and 600°C.

[0098] S7, after the heat flux of the top plate and the bottom plate of the rock sample at each test temperature point i is stable, the heat source control device continuously provides constant power q of heat to the top plate, and the temperature of the top plate and the bottom plate is detected in real time. After stabilization, the temperature difference ΔT between the top plate and the bottom plate at each test temperature point i is obtained. i .

[0099] S8, according to the temperature difference ΔT corresponding to each test temperature point i of the standard sample 1i and the corresponding constant power q, determine the thermal conductivity test value λ 测i , and according to the thermal conductivity test value λ 测i and the known theoretical value of thermal conductivity λ of the standard sample 标i , determine the heat correction amount Δqi at each test temperature point i.

[0100] In this embodiment, the mechanism of using standard samples to determine the heat correction amount Δqi at each test temperature point i is as follows: under theoretical conditions, the heat source control device provides a constant power q of heat to the top plate, and the heat is transferred from the top plate to the bottom plate in sequence. By measuring the temperature difference between the top plate and the bottom plate, the thermal conductivity can be directly calculated using the thermal conductivity theory formula. However, in fact, since the sample chamber cannot be completely insulated, there is a certain amount of heat loss in the above heat transfer process, such as heat exchange with the surroundings of the sample chamber, resulting in heat loss. In this way, there is a large error in directly calculating the thermal conductivity of the rock sample using the thermal conductivity theory formula. Therefore, it is necessary to use a standard sample to obtain the heat loss in the heat transfer process in order to correct the thermal conductivity theory formula, 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 λ at the test temperature point i 标i It is known that by placing the standard sample in the sample chamber and executing steps S6 and S7, the temperature difference ΔT of the standard sample at each test temperature point i is measured. 1i Substitute the corresponding constant power q into the thermal conductivity theory formula to obtain the thermal conductivity test value λ of the standard sample at the test temperature point i 测i , which is consistent with the theoretical value of thermal conductivity λ 标i The numerical deviation of can characterize the heat loss in the above heat transfer process, and this numerical deviation is the heat correction value Δqi.

[0101] S9, according to the temperature difference ΔT corresponding to each test temperature point i of the rock sample i And the corresponding constant power q, as well as the heat correction Δqi at the corresponding test temperature point i, determine the thermal conductivity λi of the rock sample at the corresponding test temperature point i under in-situ conversion geological conditions.

[0102] In a specific embodiment, the temperature difference ΔT corresponding to each test temperature point i of the standard sample is 1i And the corresponding constant power q, the thermal conductivity test value λ is calculated by the following formula 1 测i :

[0103]

[0104] Among them, λ 测i is the thermal conductivity test value of the standard sample measured at the test temperature point i; q is the power of the heat source control device; Δx1 is the height of the standard sample; ΔT 1i is the temperature difference between the top plate and the bottom plate of the standard sample at the test temperature point i;

[0105] According to the thermal conductivity test value λ calculated above 测i And the corresponding theoretical value of thermal conductivity λ 标i , calculate the heat correction Δqi at each test temperature point using the following formula 2:

[0106]

[0107] Where Δqi is the heat correction at the test temperature point i; λ 标i is the theoretical value of thermal conductivity of the standard sample at the test temperature i; 测i is the thermal conductivity test value of the standard sample at the test temperature point i calculated according to formula 1; ΔT 1i is the temperature difference between the top plate and the bottom plate of the standard sample at the test temperature point i; Δx1 is the height of the standard sample.

[0108] In a specific embodiment, the temperature difference ΔT corresponding to each test temperature point i of the rock sample is i and the corresponding constant power q, and the heat correction Δqi at the corresponding test temperature point (calculated by formula 2), the thermal conductivity λi of the rock sample at the corresponding test temperature point under the in-situ conversion geological conditions is calculated by the following formula 3. When implementing it specifically, the output result must ensure that the data has four decimal places:

[0109]

[0110] Where λi is the thermal conductivity of the rock sample at the test temperature point i under the in-situ conversion geological conditions; q is the constant power of the heat source device; Δqi is the heat correction at the test temperature point i; Δx is the height of the rock sample; ΔT i is the temperature difference between the top and bottom plates of the rock sample at the test temperature point i.

[0111] In this embodiment, see Figure 4-Figure 6 , using SiO2 as the standard sample to perform the above steps S6 and S7, and obtain the temperature difference ΔT corresponding to SiO2 at each test temperature point i 1i And the corresponding constant power q, determine the thermal conductivity test value λ according to formula 1 测i , according to the thermal conductivity test value λ 测i and the theoretical value of thermal conductivity of SiO2 标i , determine the heat correction value Δqi at each test temperature point i according to formula 2. Figure 5 In the Chang 7 shale layer section of the Ordos Basin, cores were taken in parallel and vertical directions at formation depths of 4070 m and 5019 m to prepare rock samples, and the above steps S1 to S7 were performed respectively, wherein formation pressures of 0.1 MPa, 10 MPa, 20 MPa, 30 MPa, and 40 MPa were applied to the rock samples by a pressure control device, and the test temperature points i were 25°C, 100°C, 200°C, 300°C, 400, 500°C, and 600°C, respectively, and the temperature difference ΔT corresponding to each test temperature point i was obtained. i and the corresponding constant power q, combined with the calculated heat correction Δqi, the dynamic thermal conductivity of Chang 7 shale in the Ordos Basin at the corresponding test temperature point i is calculated according to Formula 3: Figure 6 The results shown in the figure are the calculated results of thermal conductivity of rock samples. The lines in the figure have formation pressures that decrease from top to bottom.

[0112] Embodiment 2

[0113] See also Figure 2 and Figure 3 The present application provides a dynamic thermal conductivity testing device for in-situ conversion of shale samples, comprising: a protection chamber 1, a sample chamber 2, an inert gas protection device 3, a heat source control device 4, a sample temperature control device 5 and a pressure control device 6.

[0114] The protection chamber 1 is used to provide a closed environment;

[0115] The sample chamber 2 is arranged in the protection chamber 1 and is used to place the rock sample, wherein the rock sample is a cylindrical rock sample obtained by processing the drilling core of the in-situ conversion target area;

[0116] The inert gas protection device 3 is connected to the protection chamber 1 to provide inert gas to the protection chamber 1 and replace air, so as to provide inert gas protection to the protection chamber 1;

[0117] The sample temperature control device 5 is disposed in the sample chamber 2 and is used to control the temperature of the sample chamber 2 to reach and maintain a preset temperature;

[0118] The heat source control device 4 is connected to the top plate and the bottom plate of the rock sample respectively, and is used to provide constant power heat to the top plate and detect the temperature of the top plate and the bottom plate in real time;

[0119] The pressure control device 6 acts on the rock sample in the axial and radial directions, and is used to apply axial pressure and confining pressure under formation conditions to the rock sample.

[0120] In this embodiment, the protection chamber 1 is also a sealed chamber, and the protection chamber 1 is provided with inert gas protection by the inert gas protection device 3, so that the rock sample is always in an inert gas environment to restore the oxygen-deficient environment under the real formation, so that the detection environment is closer to the actual formation environment, so that the subsequently measured thermal conductivity is more consistent with the thermal conductivity in the actual formation environment, and its accuracy is higher.

[0121] In this embodiment, the sample chamber 2 is a sealed chamber formed by a high-temperature alloy material, which can provide a closed environment for the sample. The high-temperature alloy material can be GH4169 high-alloy steel. No specific limitation is made to the high-temperature alloy material, as long as it can withstand high temperatures and avoid deformation of the sample chamber 2 due to high temperatures.

[0122] In this embodiment, a mounting hole (not shown in the figure) detachably connected to the sample chamber 2 is provided on the outer wall of the sample chamber 2, and is used to place the rock sample in the sample chamber 2. Here, the shape of the mounting hole is not limited, and it can be round, 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. At the same time, the mounting hole should be able to be sealed and connected to the sample chamber 2 to ensure the sealing effect of the sample chamber 2.

[0123] In this embodiment, a heat preservation and insulation device is provided on the outer wall of the sample chamber 2, and the heat preservation and insulation device may include a heat preservation and insulation board (not shown in the figure) and a heat insulation sleeve (not shown in the figure). The outer wall of the sample chamber 2 is provided with a heat preservation board, and a heat insulation sleeve is sleeved on the heat preservation and insulation board. The heat preservation board and the heat insulation sleeve are both made of heat insulation materials, and the specific type of heat insulation materials is not limited here, as long as the heat loss of the sample chamber 2 can be minimized. The heat preservation and insulation device can minimize non-axial heat loss and heat convection, thereby ensuring that more than 90% of the heat of the rock sample is transmitted along the axial direction.

[0124] In a specific embodiment, the inert gas protection device 3 includes an inert gas source and an exhaust device. The inert gas source is connected to the protection chamber 1 through a gas pipe to provide inert gas. The exhaust device is connected to the protection chamber 1 through an exhaust pipe for vacuuming. A regulating valve can be set on the gas pipe and the exhaust pipe to adjust the air pressure. When in use, the rock sample is placed in the sample chamber 2, the installation hole is opened, the sample chamber 2 is connected to the protection chamber 1, the exhaust device is evacuated to a negative pressure (below -0.09Mpa), and the inert gas source is used to replenish the inert gas in the protection chamber 1 to a micro pressure (about 0.04Mpa), and then evacuated again, and repeated three times, so that the protection chamber 1 is in an inert gas environment, and then the installation hole is closed, and the inert gas is continuously filled into the protection chamber 1 to ensure that the rock sample is always in an inert gas environment during the thermal conductivity experiment.

[0125] In a specific embodiment, see Figure 3 The pressure control device 6 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.

[0126] Specifically, the three cylinder heads are connected to the top surface and two adjacent sides of the sample chamber 2 through annular flanges, the three piston connecting rods extend into the sample chamber 2 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 in contact with the top surface and the side of the rock sample, and the three cylinder barrels are provided with oil cylinder control ports, and the oil cylinder control ports 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 axial pressure and confining pressure under formation conditions to the rock sample, restoring the real formation conditions, making the detection environment closer to the actual formation environment, so that the measured thermal conductivity of the rock sample is more in line with the thermal conductivity under the actual formation environment, and its accuracy is higher. In order to avoid excessive energy loss in the sample chamber 2, a copper cooling water jacket can be set on each piston connecting rod, and each copper cooling water jacket is arranged between each cylinder head and the sample chamber 2, and is pressed by each cylinder head through annular flanges. The copper cooling water jacket can prevent the sample chamber 2 from deforming at high temperatures and affecting the sealing between the sample chamber 2 and the oil cylinder, and prevent the sample chamber 2 from generating excessive heat loss, thereby avoiding the sample temperature control device 5 from providing additional heat to compensate for the heat loss, so that the sample chamber 2 can maintain a constant temperature at a preset temperature, which can save energy.

[0127] In a specific embodiment, the heat source control device 4 includes a first heat element and a first pulse heating device. A first heat element is provided on the top plate and the bottom plate of the rock sample. The first pulse heating device is connected to each first heat element through a wire port opened on the side wall of the protection chamber 1 and the sample chamber 2. The first pulse heating device is used to perform pulse heating treatment on the first heat element. A high temperature resistant sealant is provided in the wire port for sealing. The high temperature resistant sealant can be a heat resistant epoxy sealant, a phenolic resin sealant, a silicone sealant, etc. The type of the high temperature resistant sealant is not limited here, as long as it can achieve a good sealing effect to ensure the sealing effect of the sample chamber 2.

[0128] In a specific embodiment, the sample temperature control device 5 includes a temperature sensor, a second thermal element and a second heating device.

[0129] Specifically, the second thermal element is disposed in the sample chamber 2 , the second heating device is connected to the second thermal element, and the second heating device is used to heat the second thermal element. The temperature sensor is disposed in the sample chamber 2 and is used to detect the temperature of the sample chamber 2 .

[0130] In a specific embodiment, the dynamic thermal conductivity testing device for in-situ conversion of shale samples also includes a heat source control calculation system, which is used to collect the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, as well as the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample, and the heat correction amount at the corresponding test temperature point, and determine the heat correction amount at each test temperature point according to Formula 1 and Formula 2 based on the thermal conductivity test value of the standard sample and the corresponding thermal conductivity theoretical value obtained, and calculate the thermal conductivity of the rock sample at the corresponding test temperature point under the in-situ conversion geological conditions according to Formula 3.

[0131] In summary, through the present invention, the dynamic thermal conductivity of shale samples in situ transformation is quantitatively analyzed, the reference geological environment factors are closer to the environment of the actual oil layer, and by combining a variety of testing techniques, the influence of various geological environment factors is comprehensively considered, so that more accurate and precise shale thermal conductivity data can be obtained.

[0132] A person skilled in the art will appreciate that all or part of the steps in the above-described embodiment method may be implemented by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk.

[0133] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for testing the dynamic thermal conductivity of shale samples during in-situ conversion, characterized in that: The following steps are involved: Processing the drill core of the in-situ conversion target area into a cylindrical rock sample, and measuring the size of the rock sample; Obtain standard samples; The following test steps are performed on the rock sample and the standard sample respectively: Install the rock sample in the sample chamber; Placing the sample chamber in a protection chamber, and filling the protection chamber with inert gas through an inert gas protection device; applying axial pressure and confining pressure under formation conditions to the rock sample by a pressure control device; According to the set heating conditions and each test temperature point, the rock sample is heated to the test temperature point by the sample temperature control device and the temperature of the temperature point is kept stable and balanced; After the heat flux of the top plate and the bottom plate of the rock sample at each test temperature point is stabilized, a heat source control device is used to continuously provide constant power heat to the top plate, and the temperatures of the top plate and the bottom plate are detected in real time, and after stabilization, the temperature difference between the top plate and the bottom plate at each test temperature point is obtained; Determine the thermal conductivity test value according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, and determine the heat correction amount at each test temperature point according to the thermal conductivity test value and the corresponding thermal conductivity theoretical value obtained; The thermal conductivity of the rock sample at the corresponding test temperature point under in-situ conversion geological conditions is determined according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample and the heat correction amount at the corresponding test temperature point.

2. The method for testing dynamic thermal conductivity of shale samples during in-situ conversion according to claim 1, characterized in that: Determining the thermal conductivity test value according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, and determining the heat correction amount at each test temperature point according to the thermal conductivity test value and the corresponding thermal conductivity theoretical value obtained, including: Before adding the standard sample into the sample chamber, measuring the size of the standard sample, wherein the standard sample is a sample with a known theoretical value of thermal conductivity; According to the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, the thermal conductivity test value is calculated by the following formula 1: Among them, λ 测i is the thermal conductivity test value of the standard sample measured at the test temperature point i; q is the power of the heat source control device; Δx1 is the height of the standard sample; ΔT 1i is the temperature difference between the top plate and the bottom plate of the standard sample at the test temperature point i; According to the thermal conductivity test value and the corresponding thermal conductivity theoretical value obtained, the heat correction amount at each test temperature point is calculated by the following formula 2: Where Δqi is the heat correction at the test temperature point i; λ 标i is the theoretical value of thermal conductivity of the standard sample at the test temperature i; 测i is the thermal conductivity test value of the standard sample at the test temperature point i calculated according to formula 1; ΔT 1i is the temperature difference between the top plate and the bottom plate of the standard sample at the test temperature point i; Δx1 is the height of the standard sample.

3. The method for testing dynamic thermal conductivity of shale samples during in-situ conversion according to claim 2, characterized in that: Determining the thermal conductivity of the rock sample at the corresponding test temperature point under the in-situ conversion geological condition according to the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample and the heat correction amount at the corresponding test temperature point comprises: According to the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample, as well as the heat correction amount at the corresponding test temperature point, the thermal conductivity of the rock sample at the corresponding test temperature point under the in-situ conversion geological conditions is calculated by the following formula 3: Wherein, λi is the thermal conductivity of the rock sample at the test temperature point i under the in-situ conversion geological condition; q is the constant power of the heat source device; Δqi is the heat correction at the test temperature point i; Δx is the height of the rock sample; ΔT i is the temperature difference between the top and bottom plates of the rock sample at the test temperature point i.

4. The method for testing dynamic thermal conductivity during in-situ conversion of shale samples according to claim 1, characterized in that: The step of processing the in-situ conversion target area drilling core into a cylindrical rock sample and measuring the size of the rock sample comprises: Using a waterless wire cutting technique to take a sample from a well core of an in-situ conversion target area, and processing the rock sample into a cylindrical shape using the waterless wire cutting technique, wherein the diameter of the rock sample is 2.5 cm to 4.0 cm and the height is 0.3 cm to 0.7 cm; The dimensions of the rock sample were measured using a micrometer.

5. The method for testing dynamic thermal conductivity of shale samples during in-situ conversion according to claim 1, characterized in that: The step of applying axial pressure and confining pressure under formation conditions to the rock sample by means of a pressure control device comprises: The pressure under formation conditions is applied to the rock sample in radial and axial directions respectively by the pressure control device, wherein the pressure applied by the pressure control device has a pressure range of 0 MPa to 100 MPa.

6. The method for testing dynamic thermal conductivity of shale samples during in-situ conversion according to claim 1, characterized in that: The heating condition includes a preset heating rate or a variable heating rate; According to the set heating conditions and each test temperature point, the rock sample is heated to the test temperature point by a sample temperature control device and the temperature of the temperature point is kept balanced and stable, including: According to the set heating conditions and each test temperature point, the rock sample is heated by a sample temperature control device at a preset heating rate or a variable heating rate until the temperature reaches the test temperature point, and the temperature of the test temperature point is maintained at the temperature equilibrium point for a preset time length; wherein the test temperature points include 25°C, 100°C, 200°C, 300°C, 400, 500°C and 600°C.

7. The method for testing dynamic thermal conductivity of shale samples during in-situ conversion according to claim 1, characterized in that: Also includes: When the rock sample is installed in the sample chamber, a heat preservation and insulation device is arranged on the outer wall of the sample chamber.

8. A dynamic thermal conductivity testing device for in-situ conversion of shale samples, characterized in that: include: Protection chamber, sample chamber, inert gas protection device, heat source control device, sample temperature control device and pressure control device; The protection chamber is used to provide a closed environment; The sample chamber is arranged in the protection chamber and is used to place rock samples, wherein the rock samples are cylindrical rock samples obtained by processing the core of the well in the in-situ conversion target area; The inert gas protection device is connected to the protection chamber, provides inert gas to the protection chamber and replaces air, and is used to provide inert gas protection to the protection chamber; The sample temperature control device is disposed in the sample chamber, and is used to control the temperature of the sample chamber to reach and maintain a preset temperature; The heat source control device is connected to the top plate and the bottom plate of the rock sample respectively, and is used to provide constant power heat to the top plate and detect the temperature of the top plate and the bottom plate in real time; The pressure control device acts on the rock sample in the axial and radial directions, and is used to apply axial pressure and confining pressure under formation conditions to the rock sample.

9. The dynamic thermal conductivity testing device for in-situ conversion of shale samples according to claim 8, characterized in that: The inert gas protection device comprises an inert gas source and a gas extraction device; The inert gas source is connected to the protection chamber to provide inert gas; The vacuum device is connected to the protection chamber for vacuuming.

10. The dynamic thermal conductivity testing device for in-situ conversion of shale samples according to claim 9, characterized in that: The pressure control 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 side surfaces of the rock sample; The three cylinders are connected to the hydraulic station via hydraulic oil pipes.

11. The dynamic thermal conductivity testing device for in-situ conversion of shale samples according to claim 10, characterized in that: The heat source control device includes a first heat element and a first pulse heating device; The top plate and the bottom plate of the rock sample are each provided with a first thermal element; The first pulse heating device is connected to each of the first thermal elements through the wire openings opened on the protection chamber and the side walls of the sample chamber. The first pulse heating device is used to perform pulse heating treatment on the first thermal element. The wire openings are provided with high-temperature resistant sealant for sealing.

12. The dynamic thermal conductivity testing device for in-situ conversion of shale samples according to claim 11, characterized in that: The sample temperature control device includes a temperature sensor, a second thermal element and a second heating device; The second thermal element is disposed in the sample chamber; The second heating device is connected to the second thermal element, and the second heating device is used to heat the second thermal element; The temperature sensor is disposed in the sample chamber and is used to detect the temperature of the sample chamber.

13. The dynamic thermal conductivity testing device for in-situ conversion of shale samples according to claim 12, characterized in that: It also includes a heat source control calculation system, which is used to collect the temperature difference and the corresponding constant power corresponding to each test temperature point of the standard sample, the temperature difference and the corresponding constant power corresponding to each test temperature point of the rock sample, and the heat correction amount at the corresponding test temperature point, and determine the heat correction amount at each test temperature point according to the thermal conductivity test value of the standard sample and the corresponding thermal conductivity theoretical value obtained, and calculate the thermal conductivity of the rock sample at the corresponding test temperature point under in-situ conversion geological conditions.

14. The dynamic thermal conductivity test device for in-situ conversion of shale samples according to claim 13, characterized in that: It also includes a heat preservation and insulation device, which includes a heat preservation and insulation board and a heat insulation sleeve. The outer wall of the sample chamber is provided with a heat insulation board, and the heat preservation and insulation sleeve is sleeved on the heat preservation and insulation board.

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