System and method for testing mechanical properties of underground heat source generating device

Abstract

The invention relates to a system and method for testing mechanical properties of an underground heat source generating device, and the system comprises an external condition applying unit, a first strain data testing unit, a first strain data collection unit, a second strain data testing unit and a second strain data collection unit. The external condition applying unit is used for applying conditions to the underground heat source generating device, and the first strain data testing unit is used for testing axial strain and circumferential strain of the underground heat source generating device; the first strain data acquisition unit is used for acquiring the strain, and the second strain data test unit is used for testing indirect strain generated by the second strain data test unit; and the second strain data acquisition unit is used for acquiring the indirect strain so as to calculate the radial strain of the underground heat source generation device according to the indirect strain. According to the embodiment of the invention, the problem of mechanical property testing of the underground heat source generating device under extreme environmental conditions can be effectively solved, and an important guarantee is provided for the heavy oil thermal recovery process.

Description

Technical Field

[0001] The invention belongs to the technical field of pipe string mechanical behavior simulation experiments, and in particular relates to a system and method for testing the mechanical properties of a downhole heat source generating device. Background Art

[0002] As the exploration and development of onshore oil and gas resources gradually reach saturation, oil exploration has expanded to deepwater areas. However, due to the constraints of environmental, technical and economic conditions, the production contribution of heavy oil fields above Class I-3 (350-10000mPa·s) is not high, and large-scale development still needs to be accelerated.

[0003] In order to ensure the security of national energy supply, the effective mobilization of offshore heavy oil and extra-heavy oil blocks has become particularly important. However, due to the special environment of offshore oil production platforms, the small working space, and the considerable restrictions on equipment size and placement. While being constrained by economic conditions, the more mature mining technology of onshore oil fields is also difficult to be directly promoted and implemented at sea. Against this challenging background, multi-component thermal fluid technology has emerged as an emerging offshore heavy oil reservoir mining technology, and has achieved some successful applications in the heavy oil development of Bohai Oilfield. Through extensive research and demonstration and active exploration, it is necessary to carry out exploratory research on downhole thermal generation technology.

[0004] The downhole heat source generator is a key equipment in the heavy oil thermal recovery process. Due to the harsh downhole service environment, in addition to the axial tension and compression, internal pressure, external squeeze and other operating loads, it is also subject to a series of complex environmental loads such as temperature, which may cause downhole accidents such as fracture failure. In order to ensure the safe operation of the downhole heat source generator, it is an effective measure to ensure the safety of heavy oil thermal recovery to analyze its mechanical behavior and check whether the strength of the pipe string meets the working conditions by using simulation experimental methods. Summary of the invention

[0005] In order to solve all or part of the above problems, the purpose of the present invention is to provide a system and method for testing the mechanical properties of a downhole heat source generating device. The system for testing the mechanical properties of a downhole heat source generating device of the present invention effectively solves the problem of testing the mechanical properties of a downhole heat source generating device under extreme environmental conditions.

[0006] According to one aspect of the present invention, a system for testing the mechanical properties of a downhole heat source generating device is provided. The downhole heat source generating device to be tested is a tubular structure with a closed right end, and the left end of the downhole heat source generating device is sealed and connected to a left end cap. The system comprises:

[0007] an external condition applying unit, the external condition applying unit being connected to the downhole heat source generating device, the external condition applying unit being used to apply an axial force to the downhole heat source generating device, and / or the external condition applying unit being used to introduce a heat medium into a closed cavity formed by the left end cover and the downhole heat source generating device;

[0008] a first strain data testing unit, the first strain data testing unit being used to test the axial strain and circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit;

[0009] A first strain data acquisition unit, the first strain data acquisition unit is connected to the strain data testing unit, and the first strain data acquisition unit is used to collect the axial strain and the circumferential strain;

[0010] a second strain data testing unit, the downhole heat source generating device being connected to the second strain data testing unit, the second strain data testing unit being used to test the indirect strain generated by the second strain data testing unit under the action of the external condition applying unit;

[0011] A second strain data acquisition unit, wherein the second strain data acquisition unit is connected to the second strain data testing unit, and the second strain data acquisition unit is used to acquire the indirect strain so as to calculate the radial strain of the downhole heat source generating device according to the indirect strain.

[0012] Furthermore, the external condition applying unit includes an axial force applying unit, and the axial force applying unit is used to apply axial force to the downhole heat source generating device.

[0013] Furthermore, the axial force applying unit includes a hydraulic power control system, a hydraulic oil outlet of the hydraulic power control system is connected to one end of the first branch line, a loading connecting rod is fixedly connected to the right end of the downhole heat source generating device, a flow hole is provided on the loading connecting rod and runs from the left end to the right end, the other end of the first branch line is connected to the right end of the flow hole, and the hydraulic oil of the hydraulic power control system acts on the right end of the downhole heat source generating device through the first branch line and the flow hole to apply axial force to the downhole heat source generating device through the hydraulic oil; the hydraulic power control system is driven by a servo motor.

[0014] Furthermore, the external condition application unit includes a fluid heating system, which is used to introduce heat medium into the closed cavity formed by the downhole heat source generating device and the left end cover; the downhole heat source generating device is connected to a temperature data acquisition unit, and the temperature data acquisition unit is used to obtain the actual temperature of the downhole heat source generating device after the heat medium is introduced.

[0015] Furthermore, the fluid heating system has a high-temperature fluid outlet and a low-temperature fluid inlet, a first port is provided on the left end cover, and a second port is provided at the right end of the downhole heat source generating device, the first port and the high-temperature fluid outlet, and the second port and the low-temperature fluid inlet are respectively connected through a second branch line; a one-way valve is provided at the first port or the second port.

[0016] Furthermore, the temperature data acquisition unit includes a temperature collection unit and a temperature data receiving unit, wherein the temperature collection unit is arranged in the downhole heat source generating device, and the temperature collection unit is used to collect the actual temperature of the downhole heat source generating device; the temperature collection unit is connected to the temperature data receiving unit, and the temperature data receiving unit is used to receive the actual temperature collected by the temperature collection unit.

[0017] Furthermore, the temperature acquisition unit includes several temperature sensor groups, and the several temperature sensor groups are distributed along the axial direction of the downhole heat source generating device; each group of the temperature sensor groups includes several temperature sensors, and the several temperature sensors in each group are respectively attached to the inner wall of the downhole heat source generating device along the circumferential direction of the downhole heat source generating device; each of the temperature sensors is connected to the temperature data receiving unit.

[0018] Furthermore, the first strain data testing unit includes a plurality of test strain gauge groups, and the plurality of test strain gauge groups are distributed along the axial direction of the downhole heat source generating device. Each group of the test strain gauge groups includes a plurality of axial strain gauges and a plurality of circumferential strain gauges. The plurality of axial strain gauges are used to test the axial strain generated by the downhole heat source generating device under the action of the external condition applying unit, and the plurality of circumferential strain gauges are used to test the circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit. The plurality of circumferential strain gauges in each group and the plurality of axial strain gauges in each group are attached to the outer wall of the downhole heat source generating device along the circumferential direction of the downhole heat source generating device, and each of the axial strain gauges and each of the circumferential strain gauges are connected to the first strain data acquisition unit.

[0019] Furthermore, the second strain data testing unit includes two elastic sheets symmetrically arranged about the axis of the downhole heat source generating device, the left ends of the two elastic sheets are fixed to the outer wall of the downhole heat source generating device, the right ends of the two elastic sheets are respectively connected with adjusting screws, the axes of the adjusting screws are perpendicular to the axis of the downhole heat source generating device, and each of the elastic sheets is fixedly connected with an indirect strain gauge on one side away from the downhole heat source generating device and on the other side close to the downhole heat source generating device, each of the indirect strain gauges is used to test the indirect strain generated by the elastic sheet under the action of the external condition applying unit, and each of the indirect strain gauges is connected to the second strain data acquisition unit.

[0020] Furthermore, the diameter of the left end cover is larger than the outer diameter of the downhole heat source generating device, the left end cover is connected to the outer cylinder, the outer cylinder is connected to the right end cover, and the downhole heat source generating device is located in a cavity surrounded by the left end cover, the outer cylinder and the right end cover.

[0021] The present invention also provides a method for testing the mechanical properties of a downhole heat source generating device, the method using any one of the above systems, the method comprising:

[0022] The axial strain and circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit are collected by the first strain data collecting unit, and the axial stress to which the downhole heat source generating device is subjected is calculated based on the axial strain, and the circumferential stress to which the downhole heat source generating device is subjected is calculated based on the circumferential strain;

[0023] The indirect strain generated by the second strain data testing unit under the action of the external condition applying unit is collected by the second strain data collecting unit, and the radial strain of the downhole heat source generating device is calculated according to the indirect strain;

[0024] Using the relationship between axial stress, circumferential stress, radial stress and radial strain, the radial stress on the downhole heat source generating device is calculated according to the axial stress, circumferential stress and radial strain;

[0025] The Mises stress is calculated based on the axial stress, circumferential stress and radial stress to which the downhole heat source generating device is subjected, and the mechanical properties of the downhole heat source generating device are determined based on the Mises stress.

[0026] Furthermore, after calculating the radial stress to which the downhole heat source generating device is subjected according to the axial stress, circumferential stress and radial strain by using the relationship among the axial stress, circumferential stress, radial stress and radial strain, the method further includes: calculating the internal pressure to which the downhole heat source generating device is subjected and the external pressure to which the downhole heat source generating device is subjected according to the radial stress and the circumferential stress, so as to judge the internal pressure and the external pressure to which the downhole heat source generating device is subjected according to the internal pressure and the external pressure.

[0027] It can be seen from the above technical solution that the system and method for testing the mechanical properties of a downhole heat source generating device provided by the present invention have the following beneficial effects:

[0028] The present invention can effectively solve the problem of mechanical property testing of downhole heat source generating devices under extreme environmental conditions, and provides important guarantee for the safety and efficiency of heavy oil thermal recovery process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of a system for testing the mechanical properties of a downhole heat source generating device according to an embodiment of the present invention;

[0030] Figure 2 It is a schematic diagram of the setting of the strain gauge group for testing in a plane perpendicular to the axis of the underground heat source generating device;

[0031] The reference numerals in the figure are: first port 1, clamp 2, elastic sheet 3, indirect strain gauge 4, downhole heat source generating device 5, test strain gauge group 6, axial strain gauge 61, circumferential strain gauge 62, temperature sensor 7, adjusting screw 8, outer cylinder 9, servo motor 10, right end cover 11, first branch line 12, loading connecting rod 13, second port 14, second branch line 15, fluid heating system 16, hydraulic power control system 17, temperature data receiving unit 18, first strain data acquisition unit 19, second strain data acquisition unit 20. DETAILED DESCRIPTION

[0032] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a system and method for testing the mechanical properties of a downhole heat source generating device of the present invention in conjunction with the accompanying drawings.

[0033] like Figure 1 As shown, the downhole heat source generating device 5 to be tested is a tubular structure with a closed right end, and the left end of the downhole heat source generating device 5 is sealed with a left end cover, and the sealed connection between the left end cover and the downhole heat source generating device 5 forms a closed cavity inside the downhole heat source generating device 5.

[0034] like Figure 1As shown, it shows a system for testing the mechanical properties of a downhole heat source generating device 5 according to an embodiment of the present invention, the system comprising: an external condition applying unit, a first strain data testing unit, a first strain data acquisition unit 19, a second strain data testing unit and a second strain data acquisition unit 20.

[0035] Among them, the external condition applying unit is connected to the downhole heat source generating device 5, and the external condition applying unit is used to apply axial force to the downhole heat source generating device 5, and / or the external condition applying unit is used to introduce heat medium into the closed cavity formed by the left end cover and the downhole heat source generating device 5; in this embodiment, through the setting of the external condition applying unit, the external conditions to which the downhole heat source generating device 5 is subjected, including axial force conditions and temperature conditions, are similar to the external conditions to which it is subjected when it is underground, thereby improving the accuracy of laboratory testing of the mechanical properties of the downhole heat source generating device 5.

[0036] The first strain data testing unit is used to test the axial strain and circumferential strain generated by the downhole heat source generating device 5 under the action of the external condition applying unit; the first strain data acquisition unit 19 is connected to the strain data testing unit, and the first strain data acquisition unit 19 is used to collect the axial strain and the circumferential strain; this embodiment obtains the axial strain and the circumferential strain generated by the downhole heat source generating device 5 under the action of the external conditions applied by the external condition applying unit through the cooperation of the first strain data testing unit and the first strain data acquisition unit 19.

[0037] The downhole heat source generating device 5 is connected to the second strain data testing unit, and the second strain data testing unit is used to test the indirect strain generated by the second strain data testing unit under the action of the external condition applying unit; the second strain data acquisition unit 20 is connected to the second strain data testing unit, and the second strain data acquisition unit 20 is used to acquire the indirect strain, so as to calculate the radial strain of the downhole heat source generating device 5 according to the indirect strain. In this embodiment, the indirect strain generated by the second strain data testing unit under the action of the external condition applying unit is obtained through the cooperation of the second strain data testing unit and the second strain data acquisition unit 20, so as to convert the obtained indirect strain into the radial strain of the downhole heat source generating device 5. In this embodiment, the radial strain of the downhole heat source generating device 5 under the action of the external condition applying unit is obtained.

[0038] The embodiment of the present invention can effectively solve the problem of mechanical property testing of the downhole heat source generating device 5 under extreme environmental conditions, and provides an important guarantee for the safety and efficiency of the heavy oil thermal recovery process.

[0039] In one embodiment, the external condition applying unit includes an axial force applying unit, which is used to apply an axial force to the downhole heat source generating device 5. The axial force applying unit of this embodiment is used to simulate the stress condition of the downhole heat source generating device 5 in the downhole environment, thereby ensuring the accuracy of the test.

[0040] Specifically, the axial force applying unit includes a hydraulic power control system 17, the hydraulic oil outlet of the hydraulic power control system 17 is connected to one end of the first branch line 12, the right end of the downhole heat source generating device 5 is fixedly connected with a loading connecting rod 13, and the loading connecting rod 13 is provided with a flow hole extending from the left end to the right end. The other end of the first branch line 12 is connected to the right end of the flow hole, and the hydraulic oil of the hydraulic power control system 17 acts on the right end of the downhole heat source generating device 5 through the first branch line 12 and the flow hole to apply axial force to the downhole heat source generating device 5 through the hydraulic oil; the hydraulic power control system 17 is driven by a servo motor 10.

[0041] Specifically, the hydraulic power control system 17 and the servo motor 10 are connected through a coupling, so that the servo motor 10 drives the hydraulic power control system 17, and the control by the servo motor 10 has the advantages of stability and accuracy. The hydraulic power control system 17 is, for example, a hydraulic pump, and the hydraulic power control system 17 is used to output hydraulic oil to the first branch line 12, and the output hydraulic oil acts on the right end of the downhole heat source generating device 5 through the first branch line 12 and the flow hole, so that the axial force is applied to the downhole heat source generating device 5 through the pressure of the hydraulic oil.

[0042] Among them, in one embodiment, the external condition application unit includes a fluid heating system 16, which is used to introduce heat medium into the closed cavity formed by the downhole heat source generating device 5 and the left end cover; the downhole heat source generating device 5 is connected to a temperature data acquisition unit, which is used to obtain the actual temperature of the downhole heat source generating device 5 after the heat medium is introduced.

[0043] Specifically, the fluid heating system 16 has a high-temperature fluid outlet and a low-temperature fluid inlet, a first port 1 is provided on the left end cover, a second port 14 is provided at the right end of the downhole heat source generating device 5, the first port 1 and the high-temperature fluid outlet, and the second port 14 and the low-temperature fluid inlet are connected respectively through a second branch line 15; a one-way valve is provided at the first port 1 or the second port 14.

[0044] In this embodiment, the fluid heating system 16 is used to heat the heat medium. The fluid heating system 16 has a high-temperature fluid outlet and a low-temperature fluid inlet. The heated heat medium flows out through the high-temperature fluid outlet of the fluid heating system 16. The outflowing heat medium enters the closed cavity formed by the downhole heat source generating device 5 and the left end cover through the first branch line 12 and the first port 1. The heat medium entering the closed cavity flows back to the fluid heating system 16 through the second port 14 and the second branch line 15. This embodiment realizes the recycling of the heat medium, ensuring that the heating effect of each part of the downhole heat source generating device 5 is consistent; the downhole heat source generating device 5 is heated through the setting of this embodiment, thereby realizing the simulation of the high-temperature environment in which the downhole heat source generating device 5 is located.

[0045] Among them, the temperature data acquisition unit includes a temperature collection unit and a temperature data receiving unit 18, wherein the temperature collection unit is arranged in the downhole heat source generating device 5, and the temperature collection unit is used to collect the actual temperature of the downhole heat source generating device 5; the temperature collection unit is connected to the temperature data receiving unit 18, and the temperature data receiving unit 18 is used to receive the actual temperature collected by the temperature collection unit.

[0046] The temperature acquisition unit includes several groups of temperature sensors 7, and the several groups of temperature sensors 7 are distributed along the axial direction of the downhole heat source generating device 5; each group of temperature sensors 7 includes several temperature sensors 7, and the several temperature sensors 7 in each group are respectively attached to the inner wall of the downhole heat source generating device 5 along the circumferential direction of the downhole heat source generating device 5; each temperature sensor 7 is connected to the temperature data receiving unit 18.

[0047] Specifically, the temperature data receiving unit 18 is connected to the temperature sensor 7 via a connecting wire, the connecting wire is insulated and sealed by an acrylic adhesive, and the temperature sensor 7 is adhered to the inner wall of the downhole heat source generating device 5 by epoxy resin glue. In a specific implementation, for example, the temperature acquisition unit includes two groups of temperature sensors 7, and each group of temperature sensors 7 includes two temperature sensors 7.

[0048] The setting of the temperature data receiving unit 18 and a plurality of temperature sensors 7 groups in this embodiment facilitates timely understanding of the temperature of the downhole heat source generating device 5, thereby facilitating the actual temperature of the downhole heat source generating device 5 to be close to the temperature when it works in the downhole environment by adjusting the temperature of the heat medium supplied by the fluid heating system 16, thereby making the test result more accurate.

[0049] Among them, the first strain data testing unit includes several test strain gauge groups 6, and the several test strain gauge groups 6 are evenly distributed along the axial direction of the downhole heat source generating device 5. Each group of test strain gauge groups 6 includes several axial strain gauges 61 and several circumferential strain gauges 62. The several axial strain gauges 61 are used to test the axial strain generated by the downhole heat source generating device 5 under the action of the external condition applying unit, and the several circumferential strain gauges 62 are used to test the circumferential strain generated by the downhole heat source generating device 5 under the action of the external condition applying unit. Each group of several circumferential strain gauges 62 and each group of several axial strain gauges 61 are attached to the outer wall of the downhole heat source generating device 5 along the circumferential direction of the downhole heat source generating device 5, and each axial strain gauge 61 and each circumferential strain gauge 62 are connected to the first strain data acquisition unit 19.

[0050] Specifically, the first strain data testing unit includes a plurality of test strain gauge groups 6, and the plurality of test strain gauge groups 6 are evenly distributed along the axis direction of the downhole heat source generating device 5, for example Figure 1 As shown, the test strain gauge groups 6 are four groups evenly distributed along the axial direction of the downhole heat source generating device 5; each test strain gauge group 6 includes a plurality of axial strain gauges 61 and a plurality of circumferential strain gauges 62, for example Figure 2 As shown, each test strain gauge group 6 includes four axial strain gauges 61 and four circumferential strain gauges 62. Among them, several axial strain gauges 61 are used to test the axial strain generated by the downhole heat source generating device 5 under the action of the external condition applying unit, and several circumferential strain gauges 62 are used to test the circumferential strain generated by the downhole heat source generating device 5 under the action of the external condition applying unit. Among them, each axial strain gauge 61 and each circumferential strain gauge 62 are connected to the first strain data acquisition unit 19.

[0051] Among them, the second strain data testing unit includes two elastic sheets 3 symmetrically arranged about the axis of the downhole heat source generating device 5, the left ends of the two elastic sheets 3 are fixed on the outer wall of the downhole heat source generating device 5, and the right ends of the two elastic sheets 3 are respectively connected with adjusting screws 8, and the axes of the adjusting screws 8 are perpendicular to the axis of the downhole heat source generating device 5. Each elastic sheet 3 is fixedly connected with an indirect strain gauge 4 on one side away from the downhole heat source generating device 5 and on the other side close to the downhole heat source generating device 5. Each indirect strain gauge 4 is used to test the indirect strain generated by the elastic sheet 3 under the action of the external condition applying unit, and each indirect strain gauge 4 is connected to the second strain data acquisition unit 20.

[0052] Specifically, the left ends of the two elastic sheets 3 are fixed to the outer wall of the downhole heat source generating device 5 through the clamp 2, and the right ends of the two elastic sheets 3 are respectively connected with the adjusting screws 8, and by rotating the adjusting screws 8, the adjusting screws 8 can be made to abut against the downhole heat source generating device 5. In this case, when the downhole heat source generating device 5 undergoes radial deformation (radial expansion), the corresponding adjusting screws 8 and the elastic sheets 3 will be slightly deformed, and the indirect strain gauge 4 is attached to the inner and outer sides of the elastic sheet 3. The indirect strain gauge 4 is used to test the indirect strain generated by the elastic sheet 3 under the action of the external condition applying unit, and the second strain data acquisition unit 20 is used to collect the indirect strain.

[0053] Among them, the diameter of the left end cover is larger than the outer diameter of the downhole heat source generating device 5, the left end cover is connected to the outer cylinder 9, the outer cylinder 9 is connected to the right end cover 11, and the downhole heat source generating device 5 is located in the cavity surrounded by the left end cover, the outer cylinder 9 and the right end cover 11.

[0054] In specific implementation, for example, a sealing ring is installed between the outer wall of the loading connecting rod and the right end of the downhole heat source generating device 5 to prevent fluid leakage. An extension rod block is also fixed on the outer wall of the loading connecting rod to ensure the stability of the loading system; a sealing ring is also provided between the right end cap 11 at the right end of the outer cylinder 9 and the loading connecting rod to ensure the sealing inside the device.

[0055] Among them, the embodiment of the present invention also provides a method for testing the mechanical properties of a downhole heat source generating device, the method adopts any one of the above systems, and the method comprises the following steps:

[0056] Step S001: The axial strain and circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit are collected by the first strain data collecting unit, and the axial stress σ of the downhole heat source generating device is calculated according to the axial strain. Z According to the circumferential strain, the circumferential stress σ of the underground heat source generating device is calculated. θ .

[0057] Specifically, the first strain data testing unit includes a plurality of test strain gauge groups distributed along the axial direction of the downhole heat source generating device, each test strain gauge group includes a plurality of axial strain gauges and a plurality of circumferential strain gauges, the plurality of axial strain gauges are used to test the axial strain generated by the downhole heat source generating device under the action of the external condition applying unit, and the plurality of circumferential strain gauges are used to test the circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit. After the axial strain is collected by the first strain data collecting unit, the axial stress can be obtained according to the axial strain, and after the circumferential strain is collected by the first strain data collecting unit, the circumferential stress can be obtained according to the circumferential strain.

[0058] Step S002: The indirect strain generated by the second strain data testing unit under the action of the external condition applying unit is collected by the second strain data collecting unit, and the radial strain of the downhole heat source generating device is calculated based on the indirect strain.

[0059] Specifically, for an embodiment in which two elastic sheets are provided and the indirect strain gauge is attached to a side of each elastic sheet away from the downhole heat source generating device and a side close to the downhole heat source generating device, step S002 further includes:

[0060] Step S0021: collecting strain values ​​of two indirect strain gauges on a side close to the downhole heat source generating device through the second strain data acquisition unit, and obtaining a first strain ε1 according to the two collected strain values; and collecting strain values ​​of two indirect strain gauges on a side far from the downhole heat source generating device through the second strain data acquisition unit, and obtaining a second strain ε2 according to the two collected strain values;

[0061] Step S0022: Calculate the radial strain ε of the downhole heat source generating device according to the distance a between the left end of the elastic sheet and the center of the indirect strain gauge, the distance L between the left end of the elastic sheet and the center of the adjusting screw, the first strain ε1 and the second strain ε2. r , specifically, the calculation formula is as follows:

[0062]

[0063] Step S003: using the relationship between axial stress, circumferential stress, radial stress and radial strain, the radial stress on the downhole heat source generating device is calculated according to the axial stress, circumferential stress and radial strain.

[0064] Specifically, based on the aforementioned axial stress, circumferential stress and radial strain, the radial stress σ of the downhole heat source generating device can be calculated according to Formula 2: r , Formula 2 is as follows:

[0065]

[0066] Among them, E in Formula 2 represents the elastic modulus of the material corresponding to the downhole heat source generating device, and μ represents the Poisson's ratio of the material corresponding to the downhole heat source generating device.

[0067] Step S004: Based on the axial stress σ of the downhole heat source generating device Z , circumferential stress σ θ and radial stress σ r , the Mises stress σ is calculated von , and judge the mechanical properties of the downhole heat source generating device based on the Mises stress.

[0068] Among them, the calculation formula of Mises stress is as follows:

[0069]

[0070] The Mises stress can be calculated by formula 3. After obtaining the Mises stress, it is compared with the yield strength of the material of the downhole heat source generating device. If the Mises stress is less than the yield strength of the material, it indicates that the device can work safely under the simulated conditions; otherwise, it is necessary to further optimize the design or replace the material of the downhole heat source generating device.

[0071] Wherein, when the axial force F applied by the axial force applying unit is known, the outer peripheral cross-sectional area A of the downhole heat source generating device can also be used. O 、Inner circumferential cross-sectional area A of underground heat source generating device i Calculation of axial stress σ a , and the Mises stress is calculated based on the axial stress. Specifically, the formula for calculating the axial stress based on the axial force, the outer circumferential cross-sectional area of ​​the downhole heat source generating device, and the inner circumferential cross-sectional area of ​​the downhole heat source generating device is shown in Formula 4, and the formula for calculating the Mises stress based on the axial stress is shown in Formula 5:

[0072]

[0073]

[0074] Again, in step S003, after calculating the radial stress to which the downhole heat source generating device is subjected according to the axial stress, circumferential stress and radial strain using the relationship between the axial stress, circumferential stress, radial stress and radial strain, the method of this embodiment further includes: calculating the internal pressure to which the downhole heat source generating device is subjected and the external pressure to which the downhole heat source generating device is subjected according to the radial stress and the circumferential stress, so as to judge the internal pressure and external pressure to which the downhole heat source generating device is subjected according to the internal pressure and the external pressure.

[0075] Specifically, when the radial stress σ is known r and the circumferential stress σ θ In the case of, the internal pressure of the downhole heat source generating device and the external pressure of the downhole heat source generating device can also be calculated according to Formula 6 and Formula 7:

[0076]

[0077] In formula 6 and formula 7, R i is the inner radius of the underground heat source generating device, R o is the outer radius of the underground heat source generating device, r is the distance from the center point of the section of the underground heat source generating device perpendicular to the length of the pipe to the center points of the inner wall and the outer wall of the pipe, and p iis the internal pressure of the underground heat source generating device, p o It is the external pressure on the underground heat source generating device.

[0078] The embodiments of the present invention can effectively solve the problem of mechanical property testing of a downhole heat source generating device under extreme environmental conditions, and provide important guarantee for the safety and efficiency of the heavy oil thermal recovery process.

[0079] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0080] In addition, the terms "one", "two", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0081] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A system for testing the mechanical properties of a downhole heat source generating device, wherein the downhole heat source generating device to be tested is a tubular structure with a closed right end, characterized in that: The left end of the underground heat source generating device is sealed and connected with a left end cover, and the system comprises: an external condition applying unit, the external condition applying unit being connected to the downhole heat source generating device, the external condition applying unit being used to apply an axial force to the downhole heat source generating device, and / or the external condition applying unit being used to introduce a heat medium into a closed cavity formed by the left end cover and the downhole heat source generating device; a first strain data testing unit, the first strain data testing unit being used to test the axial strain and circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit; A first strain data acquisition unit, the first strain data acquisition unit is connected to the strain data testing unit, and the first strain data acquisition unit is used to collect the axial strain and the circumferential strain; a second strain data testing unit, the downhole heat source generating device being connected to the second strain data testing unit, the second strain data testing unit being used to test the indirect strain generated by the second strain data testing unit under the action of the external condition applying unit; A second strain data acquisition unit, wherein the second strain data acquisition unit is connected to the second strain data testing unit, and the second strain data acquisition unit is used to acquire the indirect strain so as to calculate the radial strain of the downhole heat source generating device according to the indirect strain.

2. The system according to claim 1, characterized in that The external condition applying unit includes an axial force applying unit, and the axial force applying unit is used to apply axial force to the downhole heat source generating device.

3. The system according to claim 2, characterized in that The axial force applying unit includes a hydraulic power control system, a hydraulic oil outlet of the hydraulic power control system is connected to one end of a first branch line, a loading connecting rod is fixedly connected to the right end of the downhole heat source generating device, a flow hole is provided on the loading connecting rod extending from the left end to the right end, the other end of the first branch line is connected to the right end of the flow hole, and the hydraulic oil of the hydraulic power control system acts on the right end of the downhole heat source generating device through the first branch line and the flow hole to apply axial force to the downhole heat source generating device through the hydraulic oil; the hydraulic power control system is driven by a servo motor.

4. The system according to claim 1, characterized in that The external condition application unit includes a fluid heating system, which is used to introduce heat medium into the closed cavity formed by the downhole heat source generating device and the left end cover; the downhole heat source generating device is connected to a temperature data acquisition unit, which is used to obtain the actual temperature of the downhole heat source generating device after the heat medium is introduced.

5. The system according to claim 4, characterized in that The fluid heating system has a high-temperature fluid outlet and a low-temperature fluid inlet. A first port is provided on the left end cover, and a second port is provided on the right end of the downhole heat source generating device. The first port and the high-temperature fluid outlet are connected, and the second port and the low-temperature fluid inlet are connected respectively through a second branch line; a one-way valve is provided at the first port or the second port.

6. The system according to claim 4, characterized in that The temperature data acquisition unit includes a temperature acquisition unit and a temperature data receiving unit, wherein the temperature acquisition unit is arranged in the downhole heat source generating device, and the temperature acquisition unit is used to collect the actual temperature of the downhole heat source generating device; the temperature acquisition unit is connected to the temperature data receiving unit, and the temperature data receiving unit is used to receive the actual temperature collected by the temperature acquisition unit.

7. The system according to claim 6, characterized in that The temperature acquisition unit includes several temperature sensor groups, and the several temperature sensor groups are distributed along the axial direction of the downhole heat source generating device; each group of the temperature sensor groups includes several temperature sensors, and the several temperature sensors in each group are respectively attached to the inner wall of the downhole heat source generating device along the circumferential direction of the downhole heat source generating device; each of the temperature sensors is connected to the temperature data receiving unit.

8. The system according to claim 1, characterized in that The first strain data testing unit includes a plurality of test strain gauge groups, and the plurality of test strain gauge groups are distributed along the axial direction of the downhole heat source generating device. Each group of the test strain gauge groups includes a plurality of axial strain gauges and a plurality of circumferential strain gauges. The plurality of axial strain gauges are used to test the axial strain generated by the downhole heat source generating device under the action of the external condition applying unit, and the plurality of circumferential strain gauges are used to test the circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit. The plurality of circumferential strain gauges in each group and the plurality of axial strain gauges in each group are attached to the outer wall of the downhole heat source generating device along the circumferential direction of the downhole heat source generating device, and each of the axial strain gauges and each of the circumferential strain gauges are connected to the first strain data acquisition unit.

9. The system according to claim 1, characterized in that The second strain data testing unit includes two elastic sheets symmetrically arranged about the axis of the downhole heat source generating device, the left ends of the two elastic sheets are fixed to the outer wall of the downhole heat source generating device, the right ends of the two elastic sheets are respectively connected with adjusting screws, the axes of the adjusting screws are perpendicular to the axis of the downhole heat source generating device, and each of the elastic sheets is fixedly connected with an indirect strain gauge on one side away from the downhole heat source generating device and on the other side close to the downhole heat source generating device, each of the indirect strain gauges is used to test the indirect strain generated by the elastic sheet under the action of the external condition applying unit, and each of the indirect strain gauges is connected to the second strain data acquisition unit.

10. The system according to any one of claims 1 to 9, characterized in that: The diameter of the left end cover is larger than the outer diameter of the downhole heat source generating device. The left end cover is connected to an outer cylinder barrel, and the outer cylinder barrel is connected to a right end cover. The downhole heat source generating device is located in a cavity surrounded by the left end cover, the outer cylinder barrel and the right end cover.

11. A method for testing the mechanical properties of a downhole heat source generating device, characterized in that: The method adopts the system according to any one of claims 1 to 10, and the method comprises: The axial strain and circumferential strain generated by the downhole heat source generating device under the action of the external condition applying unit are collected by the first strain data collecting unit, and the axial stress to which the downhole heat source generating device is subjected is calculated based on the axial strain, and the circumferential stress to which the downhole heat source generating device is subjected is calculated based on the circumferential strain; The indirect strain generated by the second strain data testing unit under the action of the external condition applying unit is collected by the second strain data collecting unit, and the radial strain of the downhole heat source generating device is calculated according to the indirect strain; Using the relationship between axial stress, circumferential stress, radial stress and radial strain, the radial stress on the downhole heat source generating device is calculated according to the axial stress, circumferential stress and radial strain; The Mises stress is calculated based on the axial stress, circumferential stress and radial stress to which the downhole heat source generating device is subjected, and the mechanical properties of the downhole heat source generating device are determined based on the Mises stress.

12. The method according to claim 11, characterized in that After the radial stress to which the downhole heat source generating device is subjected is calculated according to the relationship among the axial stress, the circumferential stress, the radial stress and the radial strain, the method further comprises: calculating the internal pressure to which the downhole heat source generating device is subjected and the external pressure to which the downhole heat source generating device is subjected according to the radial stress and the circumferential stress, so as to judge the internal pressure and the external pressure to which the downhole heat source generating device is subjected according to the internal pressure and the external pressure.

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