Wellbore safety experimental device and method for oil shale electric heating in-situ exploitation

Abstract

The application provides a wellbore safety experiment device and method for electric heating in-situ exploitation of oil shale, and the wellbore safety experiment device comprises a thermal insulation layer, a simulated injection-production assembly arranged outside the thermal insulation layer, and oil shale raw rock, a simulated wellbore assembly, a simulated production pipe column assembly and a first stress collection assembly arranged in the thermal insulation layer. The sealed cavity is heated by an electric heater, heat is transmitted to the oil shale raw rock through the oil pipe, the casing and the closed wellbore, the cracked product of the oil shale raw rock after being heated and cracked flows into the oil pipe through the product channel, the cracked product in the oil pipe is collected through the simulated injection-production assembly, the temperature in the oil pipe is collected through the first temperature sensor, the stress borne by the casing and the oil pipe at different positions is collected in real time through the first stress collection assembly, the real downhole in-situ exploitation process is simulated, the safety of the casing and the oil pipe can be evaluated in advance before downhole exploitation, and the safety and reliability of the casing and the oil pipe during downhole exploitation can be ensured.

Description

Technical Field

[0001] This invention relates to the field of wellbore safety technology for in-situ electric heating mining of oil shale, and particularly to a wellbore safety experimental device and method for in-situ electric heating mining of oil shale. Background Technology

[0002] In-situ underground conversion technology involves the further thermal cracking of retained liquid hydrocarbons in shale to form light oil and natural gas, or the artificial thermal degradation of unconverted organic matter to generate oil and gas. In-situ underground conversion of oil shale utilizes horizontal well electrothermal lightening technology to convert heavy oil, bitumen, and various organic materials in shale buried at depths of 300–3000 m into light oil and natural gas on a large scale. Suitable organic-rich oil shale for in-situ underground conversion must meet the following conditions: a total organic carbon (TOC) value greater than 6% (the higher the better); a reverse osmosis (RO) value of 0.5%–1.0%; a thickness greater than 15 m; a burial depth less than 3000 m; and an area greater than 50 km². 2 The shale section has a well-sealed top plate and a formation water content of less than 5%. In-situ underground conversion of oil shale is a major replacement technology in the field of petroleum exploration. Summary of the Invention

[0003] The existing technology has the following shortcomings: In the existing technology, no safety test is conducted on the wellbore before mining, the safety of the wellbore during the mining process is unpredictable, and the safety and reliability are low.

[0004] In view of the above problems, it is necessary to propose a wellbore safety test device for in-situ electric heating oil shale mining to solve or partially solve the above problems. The technical solution proposed by this invention is as follows:

[0005] In a first aspect, the present invention proposes a wellbore safety experimental device for in-situ electric heating extraction of oil shale, comprising an insulation layer and a simulated injection-production assembly disposed outside the insulation layer, as well as the original oil shale rock, the simulated wellbore assembly, the simulated production tubing assembly, and a first stress acquisition assembly disposed within the insulation layer, wherein:

[0006] Wellbores were installed in the original oil shale rock;

[0007] The simulated wellbore assembly includes a closed wellbore and a casing, wherein the outer wall of the closed wellbore is fitted to the wellbore; the casing is placed in the closed wellbore, and the outer wall of the casing is fitted to the inner wall of the closed wellbore.

[0008] The simulated production tubing assembly includes tubing, an electric heater and a first temperature sensor disposed within the tubing; the tubing is disposed within the casing, and the bottom and top of the tubing are sealed to form a sealed chamber; the electric heater is used to heat the sealed chamber and transfer heat to the oil shale stock through the tubing, the casing and the sealed wellbore; the first temperature sensor is used to collect the temperature in the tubing in real time;

[0009] A product channel is also formed between the sealed wellbore, the casing, and the tubing to allow the cracking products from the thermal cracking of the original oil shale rock to be introduced into the tubing; an annulus is formed between the casing and the tubing;

[0010] The first stress acquisition component is connected to the casing and the tubing respectively, and is used to acquire the stress at different positions of the casing and the stress at different positions of the tubing in real time.

[0011] The simulated injection-production assembly is connected to the tubing and is used to collect the cracking products in the tubing.

[0012] Furthermore, the enclosed wellbore includes a cylinder, a bottom plate, and a cover plate;

[0013] The cover plate is disposed on the top of the cylinder;

[0014] The base plate is disposed at the bottom of the cylinder, the bottom of the sleeve is sealed by the base plate, and the top of the sleeve is sealed by the cover plate.

[0015] Furthermore, the simulated production tubing assembly also includes a tubing cap disposed on top of the tubing, the bottom of the tubing being connected to the base plate, and the top of the tubing being sealed by the tubing cap.

[0016] Furthermore, the simulated production tubing assembly further includes at least one simulated centralizer; the at least one simulated centralizer is connected to the tubing; and the electric heater is connected to the at least one simulated centralizer.

[0017] Furthermore, the simulated centralizer is cylindrical, and is connected to the oil pipe with an interference fit. The simulated centralizer has a first through hole at its center that allows the electric heater to pass through, and the electric heater is connected to the first through hole.

[0018] Furthermore, the electric heater is interference-fitted with the first through hole;

[0019] The simulated centralizer is provided with at least one second through hole, which is located outside the first through hole. The simulated injection-production assembly collects the cracking products in the tubing through the second through hole.

[0020] Furthermore, the sidewall of the cylinder is provided with a plurality of first perforations, the sidewall of the casing is provided with a plurality of second perforations, and the sidewall of the oil pipe is provided with a plurality of third perforations. The second perforations are respectively connected to the first perforations and the third perforations to form the product channel.

[0021] Furthermore, the first stress acquisition component includes multiple first stress sensors disposed at different positions on the outer wall of the casing and multiple second stress sensors disposed at different positions on the outer wall of the tubing.

[0022] Furthermore, the device also includes a pressure relief valve disposed outside the insulation layer, the pressure relief valve being connected to the annulus.

[0023] Furthermore, the original oil shale rock is cylindrical, and the diameter of the original oil shale rock is greater than ten times the diameter of the casing.

[0024] Furthermore, the device also includes a second stress acquisition component disposed in the original oil shale rock, for real-time acquisition of stress at different locations in the original oil shale rock.

[0025] Furthermore, the second stress acquisition component includes a plurality of third stress sensors, which are arranged at a preset distance along the radial direction of the original oil shale rock.

[0026] Furthermore, the device also includes a temperature acquisition component disposed in the original oil shale rock, for real-time acquisition of the temperature at different locations in the original oil shale rock.

[0027] Furthermore, the temperature acquisition component includes multiple second temperature sensors, which are distributed in a matrix within the original oil shale rock.

[0028] Secondly, this invention proposes a wellbore safety test method for in-situ electric heating oil shale mining, applied to the wellbore safety test device for in-situ electric heating oil shale mining, comprising:

[0029] The electric heater is activated to heat the sealed chamber, so that the heat is transferred to the oil shale protolith through the tubing, the casing and the closed wellbore, so that the cracking products of the oil shale protolith after being heated and cracked flow into the tubing through the product channel;

[0030] The simulated injection-production assembly is used to collect the cracking products in the tubing.

[0031] The temperature in the oil pipe is collected by the first temperature sensor;

[0032] The first stress acquisition component collects the stress at different locations on the casing and the stress at different locations on the tubing in real time.

[0033] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0034] This invention proposes a wellbore safety experimental device for in-situ electric heating extraction of oil shale, comprising an insulation layer and a simulated injection-production assembly disposed outside the insulation layer, as well as the original oil shale rock, the simulated wellbore assembly, the simulated production tubing assembly, and a first stress acquisition assembly disposed within the insulation layer. The electric heater heats the sealed chamber and transfers the heat to the original oil shale rock via the tubing, casing, and wellbore. A first temperature sensor collects the temperature in the tubing, and the first stress acquisition assembly collects the stress at different locations on the casing and tubing in real time. The simulated injection-production assembly collects the cracking products in the tubing, simulating the actual downhole heated in-situ extraction process. By conducting stress tests on the casing and tubing outside the well before extraction, it ensures that the real-time stress on the casing and tubing does not exceed the safe stress value at the real-time temperature, thus assessing the safety of the casing and tubing in advance and ensuring their safety and reliability during extraction. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the wellbore safety test device for in-situ electric heating mining of oil shale, as described in an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the structure of the wellbore safety test device for in-situ electric heating oil shale mining, in an embodiment of the present invention, showing the removal of the insulation layer and the original oil shale rock.

[0037] Figure 3 This is a schematic diagram of the structure of the simulated centralizer in an embodiment of the present invention;

[0038] Figure 4 This is a schematic flowchart of a wellbore safety test method for in-situ electric heating mining of oil shale, as described in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] Example 1

[0041] This invention proposes a wellbore safety experimental device for in-situ electric heating extraction of oil shale, combined with... Figure 1-3As shown, it includes an insulation layer 1 and a simulated injection-production assembly 6 disposed outside the insulation layer 1, as well as an oil shale stock 2, a simulated wellbore assembly 3, a simulated production tubing assembly 4, and a first stress acquisition assembly 5 disposed within the insulation layer 1, wherein:

[0042] The oil shale shale rock 2 is equipped with a wellbore 21. The oil shale shale rock 2 is a natural oil shale shale rock, which can be cut off from the rock mass at the bottom or not, and is insulated by a heat insulation layer 1 around it.

[0043] The simulated wellbore assembly 3 includes a closed wellbore 31 and a casing 32. The outer wall of the closed wellbore 31 is attached to the wellbore. The casing 32 is placed in the closed wellbore 31, and the outer wall of the casing 32 is attached to the inner wall of the closed wellbore 31.

[0044] The simulated production tubing assembly 4 includes tubing 42, an electric heater 41 and a first temperature sensor (not shown in the figure) disposed in the tubing 42; the tubing 42 is disposed in the casing 32, and the bottom and top of the tubing 42 are sealed to form a sealed chamber; the electric heater 41 is used to heat the sealed chamber and transfer the heat to the oil shale ore 2 through the tubing 42, the casing 32 and the sealed wellbore 31; the first temperature sensor is used to collect the temperature in the tubing 42 in real time.

[0045] In this embodiment, the first temperature sensor can be integrated into the electric heater 41. By recording the heating temperature of the electric heater 41, the heating temperature of the electric heater 41 can be used as the temperature in the oil pipe 42.

[0046] A product channel is also formed between the sealed wellbore 31, the casing 32 and the tubing 42 to allow the cracking products of the oil shale 2 after thermal cracking to be introduced into the tubing 42; an annulus is formed between the casing 32 and the tubing 42.

[0047] The first stress acquisition component is connected to the casing 32 and the oil pipe 42 respectively, and is used to acquire the stress at different positions of the casing 32 and the oil pipe 42 in real time.

[0048] The simulated injection-production component 6 is connected to the tubing 42 and is used to collect the cracking products in the tubing 42.

[0049] In this embodiment, the sealed chamber is formed by sealing the bottom and top of the tubing 42. The electric heater 41 heats the sealed chamber and transfers the heat to the oil shale protolith 2 through the tubing 42, the casing 32 and the closed wellbore 31. The cracking products of the oil shale protolith 2 after being heated and cracked flow into the tubing 42 through the product channel. The simulated injection-production assembly 6 extracts the cracking products from the tubing 42, simulating the real downhole electric heating in-situ mining process of oil shale.

[0050] This invention provides a safety experimental device for an in-situ electrically heated wellbore for oil shale mining. The device includes an insulation layer 1 and a simulated injection-production assembly 6 disposed outside the insulation layer 1, as well as the original oil shale rock 2, a simulated wellbore assembly 3, a simulated production tubing assembly 4, and a first stress acquisition assembly 5 disposed within the insulation layer 1. The sealed chamber is heated by an electric heater 41, and the heat is transferred to the original oil shale rock 2 via the tubing 42, the casing 32, and the wellbore 311. The temperature within the tubing 42 is acquired by a first temperature sensor. The first stress acquisition component 5 collects the stress at different locations of the casing 32 and the tubing 42 in real time, and the simulated injection-production component 6 collects the cracking products in the tubing 42 to simulate the actual downhole heating in-situ production process. By conducting stress experiments on the casing 32 and the tubing 42 outside the well before production, it is ensured that the real-time stress of the casing 32 and the tubing 42 does not exceed the safe stress value at the real-time temperature. The safety of the casing 32 and the tubing 42 can be assessed in advance, ensuring the safety and reliability of the casing 32 and the tubing 42 during production.

[0051] In one specific embodiment, the sealed wellbore 31 includes a cylinder 311, a bottom plate 312, and a cover plate 313; the cover plate 313 is disposed on the top of the cylinder 311; the bottom plate 312 is disposed on the bottom of the cylinder 311, the bottom of the casing 32 is sealed by the bottom plate 312, and the top of the casing 32 is sealed by the cover plate 313.

[0052] In this embodiment, the base plate 312 can be formed by cement casting, and the cylinder 311 can be made by cement rings or mud cakes. The cylinder 311, the casing 32, and the tubing 42 form a product channel. The pyrolysis products of the oil shale ore 2 after thermal pyrolysis flow into the tubing 42 through the product channel, simulating the actual downhole oil shale electric heating in-situ mining process.

[0053] In one specific embodiment, the simulated production tubing assembly 4 further includes a tubing cap 43 disposed on the top of the tubing 42, the bottom of the tubing 42 being connected to the base plate 312, and the top of the tubing 42 being sealed by the tubing cap 43.

[0054] In this embodiment, during the cement pouring process, the bottom of the oil pipe 42 can be pre-embedded in the cement to fix and seal the bottom of the oil pipe 42. The top of the oil pipe 42 is sealed by the oil pipe cover 43 to form the sealed chamber, simulating the sealed environment of the actual production tubing.

[0055] In one specific embodiment, the simulated production tubing assembly 4 further includes at least one simulated centralizer 44; the at least one simulated centralizer 44 is connected to the tubing 42; the electric heater 41 is connected to the simulated centralizer 44. Fixing the electric heater 41 via the tubing 42 and the simulated centralizer 44 ensures that the electric heater 41 will not sway within the tubing 42, improving the stability and reliability of the electric heater 41, thereby enhancing the stability and reliability of the device. Figure 2 As shown, two simulated centralizers 44 are set to fix the electric heater 41. Of course, the number of simulated centralizers 44 can be one or more, which can be set according to the actual fixing requirements.

[0056] In a further specific embodiment, such as Figure 3 As shown, the simulated centralizer 44 is cylindrical and is interference-fitted to the oil pipe 42. A first through hole 441, allowing the electric heater 41 to pass through, is located at the center of the simulated centralizer 44. The electric heater 41 is connected to the first through hole 441. The outer wall of the simulated centralizer 44 is fitted against the inner wall of the oil pipe 42, and the interference fit between the simulated centralizer 44 and the oil pipe 42 achieves the connection. The electric heater 41 is inserted into the first through hole 441, thus securing the electric heater 41.

[0057] In a further specific embodiment, the electric heater 41 is interference-fitted with the first through-hole 441; the simulated centralizer 44 is provided with at least one second through-hole 442, the second through-hole 442 being located outside the first through-hole 441, and the simulated injection-production assembly 6 collects the cracking products in the tubing 42 through the second through-hole 442. Figure 3 As shown, the electric heater 41 is inserted into the first through hole 441, and the electric heater 41 is interference-fitted with the first through hole 441 to fix the electric heater 41. The simulated centralizer 44 is provided with two second through holes 442, which are inclined slot holes. The cracking products in the oil pipe 42 pass through the second through holes 442 under pressure and are then extracted by the simulated injection and production assembly 6. The number of second through holes 442 can be one or more, which can be set according to the actual fixing requirements.

[0058] In one specific embodiment, the sidewall of the cylinder 311 is provided with multiple first perforations (not shown in the figure), the sidewall of the casing 32 is provided with multiple second perforations (not shown in the figure), and the sidewall of the tubing 42 is provided with multiple third perforations (not shown in the figure). The second perforations are respectively connected to the first perforations and the third perforations to form the product channel. The first perforations and the annulus are connected through the second perforations, and the annulus is connected through the third perforations to form the product channel. The pyrolysis products of the oil shale brook 2 after thermal pyrolysis flow into the tubing 42 sequentially through the first perforations, the second perforations, the annulus, and the third perforations, simulating the injection and production process of real downhole in-situ mining of oil shale brook 2.

[0059] In one specific embodiment, the first stress acquisition component 5 includes a plurality of first stress sensors 51 disposed on the outer wall of the casing 32 and a plurality of second stress sensors 52 disposed on the outer wall of the tubing 42. The plurality of first stress sensors 51 are used to acquire stresses at different positions of the casing 32 in real time, and the plurality of second stress sensors 52 are used to acquire stresses at different positions of the tubing 42 in real time.

[0060] Specifically, such as Figure 2 As shown, the plurality of first stress sensors 51 can be uniformly arranged at a certain spacing along the outer wall of the casing 32, and the plurality of second stress sensors 52 can be uniformly arranged at a certain spacing along the outer wall of the tubing 42. Before well drilling, the stress of the casing 32 is tested outside the well using the first stress sensors 51, and the stress of the tubing 42 is tested using the second stress sensors 52. This ensures that the real-time stress of the casing 32 and the tubing 42 does not exceed the safe stress value at the real-time temperature, and the safety of the casing 32 and the tubing 42 can be assessed in advance, thus ensuring the safety and reliability of the casing 32 and the tubing 42 during well drilling. The first stress sensors 51 and the second stress sensors 52 preferably employ ultra-high temperature strain gauges to measure stress in a high-temperature environment.

[0061] In a further specific embodiment, the device also includes a pressure relief valve 7 disposed outside the insulation layer 1, the pressure relief valve 7 being in communication with the annulus. By configuring the pressure relief valve 7 to be in communication with the annulus, when the pressure in the annulus exceeds a preset safety pressure value, the pressure relief valve 7 opens to release the pressure, which can improve the safety of the device and prevent injury to experimental personnel.

[0062] In one specific embodiment, the original oil shale rock 2 is cylindrical, and its diameter is greater than ten times the diameter of the casing 32. By setting the diameter of the original oil shale rock 2 to be greater than ten times the diameter of the casing 32, the actual downhole electric heating in-situ mining environment of oil shale is simulated. The experimental environment is closer to the actual downhole mining environment, and the experimental results are more reliable and referential.

[0063] In a further specific embodiment, such as Figure 1 As shown, the device also includes a second stress acquisition component 8 disposed in the original oil shale rock 2, used to acquire stress at different locations in the original oil shale rock 2 in real time. By acquiring stress at different locations in the original oil shale rock 2 in real time through the second stress acquisition component 8, and comparing the stress of the original oil shale rock 2 with the stress on the casing 32, the influence of the stress of the original oil shale rock 2 on the stress on the casing 32 can be analyzed.

[0064] In a further specific embodiment, the second stress acquisition component 8 includes a plurality of third stress sensors 81, which are arranged at preset distances along the radial direction of the original oil shale rock 2. Figure 1 As shown, on both sides of the wellbore 21 of the oil shale protolith 2, multiple third stress sensors 81 are arranged orthogonally along the radial direction of the oil shale protolith 2 at preset distances. Stress in the oil shale protolith 2 is collected by sampling to obtain stress at different locations within the oil shale protolith 2. The third stress sensors 81 are preferably ultra-high temperature strain gauges to measure stress under high-temperature conditions.

[0065] In a further specific embodiment, such as Figure 1 As shown, the device also includes a temperature acquisition component 9 installed in the original oil shale rock 2, used to acquire the temperature at different locations in the original oil shale rock 2 in real time. By acquiring the temperature at different locations in the original oil shale rock 2 in real time through the temperature acquisition component 9, and combining it with the temperature in the sleeve 32 acquired by the first temperature sensor, the heat transfer efficiency can be analyzed, thereby providing a reference for setting the heating process parameters of the electric heater 41.

[0066] In a further specific embodiment, the temperature acquisition component 9 includes a plurality of second temperature sensors 91, which are distributed in a matrix within the original oil shale rock 2. Figure 1As shown, since the two sides of the oil shale shale 2 are symmetrical, on one side of the wellbore 21, several second temperature sensors 91 are set at certain intervals along two straight lines in the radial direction and several second temperature sensors 91 are set at certain intervals along the axial direction. The two ends of the line connecting the several second temperature sensors 91 set in the axial direction are the second temperature sensors 91 set in the radial direction, forming a matrix distribution. This allows for the measurement of the temperature at different positions of the oil shale shale 2 along the axial and longitudinal directions, thereby making the collected temperature data more comprehensive and accurate.

[0067] The wellbore safety experimental device for in-situ electric heating oil shale mining proposed in this embodiment of the invention has the following functions:

[0068] (1) The experimental device described in this invention can be used to simulate electric heating in situ production wells of oil shale and to simulate full-scale pilot-scale experiments of hot fluid production injection, so as to evaluate the design of heat injection process parameters for in situ production wells.

[0069] (2) The experimental device described in this invention can be used to determine the basic thermodynamic physical property parameters of oil shale during thermal cracking, study the variation law of thermophysical properties with temperature and the directional difference law with the occurrence of rock strata, construct a prediction model of thermodynamic physical property parameters of the study area, and provide engineering design drawings of thermodynamic physical property parameters of the study area.

[0070] (3) Through the experimental apparatus described in this invention, key influencing factors on wellbore safety and stability during the in-situ production of oil shale can be studied, and the comprehensive influence of various influencing factors on the simulated wellbore component 3 can be evaluated. Key influencing factors include: the coupling effect of the initial geostress field and temperature field of oil shale, the coupling effect analysis of the thermal displacement of the cement sheath of casing 32 and cylinder 311 with the rock at wellbore 21, the coupling effect analysis of the trajectory of horizontal wellbore 21 with formation heterogeneity, the coupling effect analysis of fluid seepage mass transfer and heat transfer process with thermal stress, the defects of cement sheath of casing 32 and cylinder 311, the coupling effect of the centering of casing 32 and tubing 42 with thermal stress, etc.

[0071] (4) The experimental apparatus described in this invention can be used to study and evaluate the impact of engineering factors on wellbore safety during the construction of in-situ oil shale production wells. Engineering factors for in-situ production wells include: evaluation of the anti-collapse effect of casing 32 under different completion conditions; evaluation and model construction of the impact of heterogeneity differences in the surrounding rock on the collapse effect of casing 32; evaluation and control of casing 32 defects or cement sheath defects in the cylinder 311 on wellbore integrity; and evaluation of the impact of open hole quality and cylinder 311 mud cake thickness on wellbore integrity.

[0072] (5) Through the research method described in this invention, the mutual influence between the power of the electric heater 41 and the integrity of the tubing 42 can be evaluated, a tubing 42 integrity evaluation model can be established, the influence of different construction conditions (centering of the electric heater 41) on the thermal stress distribution of the tubing 42 can be studied, key control measures for the safety of the tubing 42 and well tools and instruments can be studied, and the structural integrity and buckling stability of the tubing 42 under different geostress distributions, different confining pressures, and different thermal internal stress coupling effects can be simulated.

[0073] Example 2

[0074] This invention provides a wellbore safety test method for in-situ electric heating oil shale extraction, applied to the wellbore safety test device for in-situ electric heating oil shale extraction described in Example 1, such as... Figure 4 As shown, it includes:

[0075] Step S101: Start the electric heater to heat the sealed chamber, so that the heat is transferred to the oil shale protolith through the tubing, the casing and the closed wellbore, so that the cracking products of the oil shale protolith after being heated and cracked flow into the tubing through the product channel.

[0076] Step S102: Collect the cracking products in the tubing using the simulated injection and production assembly.

[0077] Step S103: Collect the temperature in the oil pipe using the first temperature sensor.

[0078] Step S104: The first stress acquisition component is used to acquire the stress at different locations of the casing and the stress at different locations of the tubing in real time.

[0079] This invention proposes a wellbore safety test method for in-situ electric heating extraction of oil shale. The method involves heating the sealed chamber with an electric heater and transferring the heat to the original oil shale rock via the tubing, casing, and wellbore. A first temperature sensor collects the temperature in the tubing, and a first stress acquisition component collects the stress at different locations on the casing and tubing in real time. A simulated injection-production component collects the cracking products in the tubing, simulating the actual downhole heated in-situ extraction process. By conducting stress tests on the casing and tubing outside the well before extraction, the method ensures that the real-time stress on the casing and tubing does not exceed the safe stress value at the real-time temperature. This advance assessment of the casing and tubing's safety ensures their safety and reliability during well extraction.

[0080] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0081] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A wellbore safety experimental device for in-situ electric heating mining of oil shale, characterized in that, It includes an insulation layer and a simulated injection-production assembly disposed outside the insulation layer, as well as the original oil shale rock, a simulated wellbore assembly, a simulated production tubing assembly, and a first stress acquisition assembly disposed within the insulation layer, wherein: Wellbores were installed in the original oil shale rock; The simulated wellbore assembly includes a closed wellbore and a casing, wherein the outer wall of the closed wellbore is fitted to the wellbore; the casing is placed in the closed wellbore, and the outer wall of the casing is fitted to the inner wall of the closed wellbore. The simulated production tubing assembly includes tubing, an electric heater and a first temperature sensor disposed within the tubing; the tubing is disposed within the casing, and the bottom and top of the tubing are sealed to form a sealed chamber; the electric heater is used to heat the sealed chamber and transfer heat to the oil shale stock through the tubing, the casing and the sealed wellbore; the first temperature sensor is used to collect the temperature in the tubing in real time; A product channel is also formed between the sealed wellbore, the casing, and the tubing to allow the cracking products from the thermal cracking of the original oil shale rock to be introduced into the tubing; an annulus is formed between the casing and the tubing; The first stress acquisition component is connected to the casing and the tubing respectively, and is used to acquire the stress at different positions of the casing and the stress at different positions of the tubing in real time. The simulated injection-production assembly is connected to the tubing and is used to collect the cracking products in the tubing.

2. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 1, characterized in that, The enclosed wellbore includes a cylinder, a bottom plate, and a cover plate; The cover plate is disposed on the top of the cylinder; The base plate is disposed at the bottom of the cylinder, the bottom of the sleeve is sealed by the base plate, and the top of the sleeve is sealed by the cover plate.

3. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 2, characterized in that, The simulated production tubing assembly also includes a tubing cap disposed on top of the tubing, the bottom of the tubing being connected to the base plate, and the top of the tubing being sealed by the tubing cap.

4. The wellbore safety experimental device for in-situ electric heating oil shale mining as described in claim 3, characterized in that, The simulated production tubing assembly also includes at least one simulated centralizer; the at least one simulated centralizer is connected to the tubing; and the electric heater is connected to the at least one simulated centralizer.

5. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 4, characterized in that, The simulated centralizer is cylindrical and is connected to the oil pipe with an interference fit. The simulated centralizer has a first through hole at its center that allows the electric heater to pass through, and the electric heater is connected to the first through hole.

6. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 5, characterized in that, The electric heater is interference-fitted with the first through hole; The simulated centralizer is provided with at least one second through hole, which is located outside the first through hole. The simulated injection-production assembly collects the cracking products in the tubing through the second through hole.

7. The wellbore safety test device for in-situ electric heating mining of oil shale as described in any one of claims 2-6, characterized in that, The sidewall of the cylinder is provided with a plurality of first perforations, the sidewall of the casing is provided with a plurality of second perforations, and the sidewall of the tubing is provided with a plurality of third perforations. The second perforations are respectively connected to the first perforations and the third perforations to form the product channel.

8. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 7, characterized in that, The first stress acquisition component includes multiple first stress sensors disposed at different positions on the outer wall of the casing and multiple second stress sensors disposed at different positions on the outer wall of the tubing.

9. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 8, characterized in that, It also includes a pressure relief valve disposed outside the insulation layer, the pressure relief valve being connected to the annulus.

10. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 9, characterized in that, The original oil shale rock is cylindrical, and the diameter of the original oil shale rock is more than ten times the diameter of the casing.

11. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 10, characterized in that, It also includes a second stress acquisition component installed in the original oil shale rock, used to acquire stress at different locations in the original oil shale rock in real time.

12. The wellbore safety experimental device for in-situ electric heating oil shale mining as described in claim 11, characterized in that, The second stress acquisition component includes multiple third stress sensors, which are arranged at preset distances along the radial direction of the original oil shale rock.

13. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 12, characterized in that, It also includes a temperature acquisition component installed in the original oil shale rock, used to collect the temperature at different locations in the original oil shale rock in real time.

14. The wellbore safety experimental device for in-situ electric heating mining of oil shale as described in claim 13, characterized in that, The temperature acquisition component includes multiple second temperature sensors, which are distributed in a matrix within the original oil shale rock.

15. A wellbore safety test method for in-situ electric heating oil shale mining, applied to the wellbore safety test apparatus for in-situ electric heating oil shale mining as described in any one of claims 1-14, characterized in that, include: The electric heater is activated to heat the sealed chamber, so that the heat is transferred to the oil shale protolith through the tubing, the casing and the closed wellbore, so that the cracking products of the oil shale protolith after being heated and cracked flow into the tubing through the product channel; The simulated injection-production assembly is used to collect the cracking products in the tubing. The temperature in the oil pipe is collected by the first temperature sensor; The first stress acquisition component collects the stress at different locations on the casing and the stress at different locations on the tubing in real time.

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