Rock friction coefficient measuring system

Abstract

The invention relates to the field of oil and gas drilling and production experiments, and discloses a rock friction coefficient measuring system which comprises a soaking unit and a detection unit, and the soaking unit is used for simulating underground drilling fluid to soak a first rock sample and a second rock sample; the detection unit comprises a loading mechanism, a displacement driving mechanism, a load detection device and a friction force detection device, the loading mechanism is used for applying a load to the first rock sample and the second rock sample which are sequentially stacked up and down after soaking, and the displacement driving mechanism is used for driving the second rock sample to move relative to the first rock sample; the load detection device is used for detecting the load applied by the loading mechanism, and the friction force detection device is used for detecting the friction force applied to the first rock sample by the second rock sample. According to the rock friction coefficient measuring system, the condition that drilling fluid invades into a rock fracture zone in the drilling process can be simulated, and accurate measurement of the rock friction coefficient when the drilling fluid invades is achieved.

Description

Technical Field

[0001] This application belongs to the technical field of oil and gas drilling and production experiments, and specifically relates to a rock friction coefficient measurement system. Background Art

[0002] During the process of oil drilling, the interaction between drilling fluid and formation rocks has an important impact on drilling efficiency, wellbore stability, and drilling safety. The immersion of drilling fluid will change the physical and chemical properties of rocks, thereby affecting the friction coefficient of rocks. The change in the rock friction coefficient will affect the contact state between the drill bit and the rock, the frictional torque of the drill string, and the stability of the wellbore. Therefore, accurately measuring the influence of drilling fluid immersion on the rock friction coefficient is of great significance for optimizing the performance of drilling fluid, improving drilling efficiency, and ensuring drilling safety.

[0003] Currently, the methods for measuring the rock friction coefficient mainly include the inclined plate method, the shear box method, and the rotational friction method, etc. However, most of these methods cannot simulate the influence of drilling fluid immersion on rocks, and there are significant differences between the experimental conditions and the actual drilling conditions, resulting in the measurement results being difficult to accurately reflect the actual situation. Summary of the Invention

[0004] Aiming at the above-mentioned at least one defect or deficiency of the prior art, this application provides a rock friction coefficient measurement system, which can simulate the situation of drilling fluid invading the rock fracture zone during the drilling process and achieve accurate measurement of the rock friction coefficient when the drilling fluid invades.

[0005] To achieve the above object, this application provides a rock friction coefficient measurement system, including:

[0006] An immersion unit for simulating downhole drilling fluid to immerse a first rock sample and a second rock sample; and

[0007] A detection unit, including a loading mechanism, a displacement driving mechanism, a load detection device, and a friction force detection device. The loading mechanism is used to apply a load to the first rock sample and the second rock sample stacked one above the other after immersion. The displacement driving mechanism is used to drive the second rock sample to move relative to the first rock sample. The load detection device is used to detect the load applied by the loading mechanism, and the friction force detection device is used to detect the friction force applied by the second rock sample on the first rock sample.

[0008] In some embodiments, the immersion unit includes an immersion container, a heating device, and a liquid supply mechanism. The immersion container is used to accommodate the first rock sample and / or the second rock sample. The liquid supply mechanism is used to input drilling fluid into the immersion container, and the heating device is used to heat the drilling fluid in the immersion container.

[0009] In some embodiments, the soaking unit further includes a pressure detection device and a temperature detection device, and the pressure detection device and the temperature detection device are respectively configured to detect the hydraulic pressure and temperature of the drilling fluid in the soaking container.

[0010] In some embodiments, the liquid supply mechanism includes a liquid pump and a pressure control device. The liquid pump is connected to the soaking container through a pipeline, and the pressure control device is arranged in the pipeline and configured to control the hydraulic pressure of the drilling fluid input into the soaking container.

[0011] And / or, the heating device is provided with a temperature controller for controlling the heating temperature.

[0012] In some embodiments, the soaking container is provided with a rock sample support assembly for fixing the first rock sample and / or the second rock sample in the middle of the cavity of the soaking container.

[0013] In some embodiments, the loading mechanism includes a gantry and a loading pressure rod. The loading pressure rod hangs vertically from the cross beam of the gantry and is configured to press against the first rock sample.

[0014] In some embodiments, the cross beam of the gantry is provided with a frictionless slide rail and a slider that forms a sliding fit with the frictionless slide rail. The loading pressure rod is fixedly connected to the slider, and the friction force detection device is configured to be connected between the vertical column of the gantry and the first rock sample.

[0015] In some embodiments, the slider is provided with a threaded hole, and the loading pressure rod is formed as a screw rod that passes through the threaded hole and forms a threaded connection with the threaded hole.

[0016] Or, the loading mechanism includes a loading oil cylinder fixedly connected to the slider, and the loading pressure rod is the piston rod of the loading oil cylinder.

[0017] In some embodiments, the displacement driving mechanism is arranged on the vertical column of the gantry and is formed as a linear driving mechanism.

[0018] In some embodiments, the rock friction coefficient measurement system further includes a data processing device. The data processing device communicates with the load detection device and the friction force detection device respectively, and is configured to determine that the second rock sample moves relative to the first rock sample when it is determined that the floating value of the friction force is within a preset allowable floating range, and calculate the rock friction coefficient according to the real-time load and the friction force.

[0019] Through the above technical solution, the rock friction coefficient measurement system of the present application can use the soaking unit to soak the rock sample to be measured, so as to prepare a rock sample with a height similar to that of the rock fracture zone invaded by drilling fluid during the actual drilling process, ensuring the accuracy of subsequent rock friction coefficient measurement. The loading mechanism of the detection unit is used to apply a load to the first and second rock samples stacked on top of each other after soaking, so as to simulate the extrusion state of in-situ stress on rock fragmentation during the actual drilling process. In this state, the displacement driving mechanism is used to drive the second rock sample to move relative to the first rock sample, and at the same time, the friction force detection device is used to detect the friction force exerted by the second rock sample on the first rock sample during movement. Then, according to this friction force and the load applied by the loading mechanism, the friction coefficient of the rock sample under the loading state can be accurately calculated, so as to apply the test results to the drilling site in the fracture zone area, thereby reducing the influence of wellbore instability in the formation with fracture zones and reducing economic losses.

[0020] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific embodiment part. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings are used to provide a further understanding of the embodiments of the present application, and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present application, but do not constitute a limitation to the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings. In the drawings:

[0022] Figure 1 It is a schematic diagram of the soaking unit of a rock friction coefficient measurement system in a specific embodiment of the present application;

[0023] Figure 2 It is a schematic diagram of the heating device and temperature detection device of a rock friction coefficient measurement system in a specific embodiment of the present application;

[0024] Figure 3 It is a schematic diagram of the detection unit and data processing device of a rock friction coefficient measurement system in a specific embodiment of the present application.

[0025] DESCRIPTION OF THE REFERENCE NUMERALS

[0026] 1 Loading mechanism 2 Displacement driving mechanism

[0027] 3 Load detection device 4 Friction force detection device

[0028] 5 Soaking container 6 Heating device

[0029] 7 Liquid supply mechanism 8 Pressure detection device

[0030] 9 Temperature detection device 10 Rock sample support assembly

[0031] 11 Data processing device 12 First rock sample

[0032] 13 Second rock sample

[0033] 101 Gantry 102 Loading pressure bar

[0034] 103 Unobstructed slide rail 104 Slide block

[0035] 601 Temperature controller 701 Liquid pump

[0036] 702 Pressure control device Detailed implementation manners

[0037] The following will describe in detail the detailed implementation manners of the present application with reference to the accompanying drawings. It should be understood that the detailed implementation manners described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0038] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with exemplary embodiments.

[0039] First of all, it should be noted that the instability of the fracture zone wellbore is an important phenomenon in the drilling engineering. The main reason is that the invasion of drilling fluid causes a significant reduction in the friction coefficient between rock blocks, especially during the process of the drill bit drilling. In actual drilling, at the moment when the formation is drilled (the drilling fluid has not invaded the wellbore yet), under the action of in-situ stress, the contact surface between unit bodies is squeezed and has a certain anti-sliding ability. However, as time goes by, the pressure transmission of the drilling fluid causes an increase in the pore and fracture pressures around the wellbore, reducing the extrusion force between rocks and at the same time reducing the friction coefficient, resulting in a significant decrease in the frictional force and easily causing the instability of rock blocks. During the drilling process in the fractured formation, if the rock friction coefficient at different times cannot be predicted, it may lead to wellbore instability such as collapse and caving, resulting in expensive maintenance costs.

[0040] In view of this, as Figures 1 to 3 shown, the exemplary embodiment of the present application provides a rock friction coefficient measurement system. The measurement system mainly includes an immersion unit and a detection unit. Among them, the immersion unit is used to simulate the downhole drilling fluid to immerse the first rock sample 12 and the second rock sample 13. For example, a water-based drilling fluid can be used for immersion. The detection unit includes a loading mechanism 1, a displacement driving mechanism 2, a load detection device 3, and a friction force detection device 4. The loading mechanism 1 is used to apply a load to the first rock sample 12 and the second rock sample 13 that are stacked one above the other after immersion. For example, referring to Figure 3, the first rock sample 12 and the second rock sample 13 stacked one above the other can be placed on a horizontal operating table. The loading mechanism 1 applies a load downward to the top surface of the first rock sample 12, so that the bottom surface of the first rock sample 12 presses against the top surface of the second rock sample 13. Wherein, the bottom surface of the first rock sample 12 and the top surface of the second rock sample 13 can both be parallel to the horizontal plane. The displacement driving mechanism 2 is used to drive the second rock sample 13 to move relative to the first rock sample 12. For example, referring to Figure 3 , the displacement driving mechanism 2 is arranged on one side of the second rock sample 13, and applies a tensile force or a thrust force perpendicular to the load direction to the second rock sample 13, so that the second rock sample 13 moves relative to the first rock sample 12. The load detection device 3 is used to detect the load applied by the loading mechanism 1 in real time, and the friction force detection device 4 is used to detect the friction force applied by the second rock sample 13 on the first rock sample 12 in real time.

[0041] It can be seen that the rock friction coefficient measurement system of the present exemplary embodiment can use the soaking unit to soak the rock sample to be measured, so as to prepare a rock sample similar to the height of the rock fracture zone invaded by drilling fluid during the actual drilling process, ensuring the accuracy of subsequent rock friction coefficient measurement. The loading mechanism 1 applies a load to the first rock sample 12 and the second rock sample 13 stacked one above the other after soaking, so as to simulate the extrusion state of in-situ stress on rock fragmentation during the actual drilling process. In this state, the displacement driving mechanism is used to drive the second rock sample 13 to move relative to the first rock sample 12, and at the same time, the friction force detection device 4 is used to detect the friction force applied by the second rock sample 13 on the first rock sample 12 during movement. Then, the rock friction coefficient under the loading state can be accurately calculated according to this friction force and the load applied by the loading mechanism 1, so as to apply the test results to the drilling site in the fracture zone area, thereby reducing the influence of wellbore instability in the formation with fracture zones and reducing economic losses.

[0042] It should be added that both the first rock sample 12 and the second rock sample 13 can be taken from the cores of underground rock formations in the actual drilling path. Usually, the first rock sample 12 and the second rock sample 13 are made of the same material, but the first rock sample 12 and the second rock sample 13 with different materials can also be selected according to measurement requirements. Preferably, a cylindrical rock sample is selected as the first rock sample 12, and a rock sample with a large enough top surface is selected as the second rock sample 13, such as a rectangular rock sample, so that the sliding path of the second rock sample 13 relative to the first rock sample 12 is long enough.

[0043] In this embodiment, the rock friction coefficient can be calculated according to the measured friction force and load, and the formula is as follows:

[0044] Wherein, μ is the rock friction coefficient, g is the acceleration of gravity, F N (N) is the load, f(N) is the friction force, and m is the weight of the first rock sample after soaking.

[0045] Refer to Figure 1 , the soaking unit mainly includes a soaking container 5, a heating device 6 and a liquid supply mechanism 7. Among them, the soaking container 5 is a high-temperature and high-pressure resistant container for accommodating the first rock sample 12 and / or the second rock sample 13, that is, accommodating two rock samples at the same time or only one of them. The liquid supply mechanism 7 is used to input drilling fluid into the soaking container 5, so as to form a certain hydraulic state in the soaking container 5. The heating device 6 is used to heat the drilling fluid in the soaking container 5 to make the drilling fluid reach a certain temperature, so as to simulate the pressure conditions and temperature conditions of different formations during the drilling process, ensure a high simulation degree of the soaking process of the rock sample, and improve the accuracy of subsequent friction coefficient measurement.

[0046] To meet the requirements of precise control of pressure conditions and temperature conditions, the soaking unit may include a control part and a detection part. As Figure 1 and Figure 2 shown, the detection part may include a pressure detection device 8 and a temperature detection device 9. Among them, the pressure detection device 8 may be arranged in the infusion pipeline or the soaking container 5. For example, a piezoelectric pressure sensor or a mechanical pressure gauge, etc. may be used to detect the hydraulic pressure of the drilling fluid input into the soaking container 5 in real time. The temperature detection device 9 may select a contact temperature sensor, such as a thermocouple temperature sensor, a thermal resistance temperature sensor, etc., which may be installed in the soaking container 5 to detect the temperature of the drilling fluid in the soaking container 5 in real time. The control part may include a pressure control device 702 arranged in the liquid supply mechanism 7 and a temperature controller 601 arranged in the heating device 6. Specifically, the pressure control device 702 may be arranged in the infusion pipeline and adopt manual control or electrical control, etc., that is, control the hydraulic pressure of the drilling fluid by manual control or automatic control. Among them, in the case of automatic control, the pressure control device 702 may communicate with the pressure detection device 8 and be configured to control the outlet pressure to be constant when the hydraulic pressure reaches a preset pressure value, so as to ensure that the hydraulic pressure value in the soaking container 5 is constant. In the case of manual control, the reading of the pressure detection device 8 may be visually inspected manually to judge whether the hydraulic pressure reaches the preset pressure value, and then the outlet pressure of the pressure control device 702 may be adjusted manually to make the outlet pressure constant. Relatively speaking, the accuracy will be higher and the efficiency will be better by the communication and cooperation between the pressure control device 702 and the pressure detection device 8 for judgment.

[0047] Similarly, the temperature controller 601 can also adopt methods such as manual control or electrical control, that is, control the heating temperature of the drilling fluid by manual control or automatic control. Among them, in the case of automatic control, the temperature controller 601 can communicate with the temperature detection device 9 and is configured to control the heating power of the heating device 6 to be constant when the temperature of the drilling fluid reaches a preset temperature value, so as to ensure the constant temperature of the drilling fluid in the soaking container 5. In the case of manual control, the reading of the temperature detection device 9 can be visually observed manually to judge whether the heating temperature reaches the preset temperature value, and then the temperature controller 601 can be manually adjusted to control the heating power of the heating device 6. Relatively speaking, the judgment through the communication and cooperation between the temperature controller 601 and the temperature detection device 9 has higher accuracy and better efficiency.

[0048] Further, referring to Figure 1 , the liquid supply mechanism 7 further includes a liquid pump 701. The liquid pump 701 is connected to the soaking container 5 through a pipeline and is used to pump the drilling fluid into the soaking container 5. The pressure control device 702 is arranged in the pipeline between the liquid pump 701 and the soaking container 5. In some embodiments, a constant-pressure liquid pump can also be used as the liquid pump 701 to achieve the constant-pressure transportation of the drilling fluid. At this time, the pressure control device 702 can be a variable mechanism in the constant-pressure liquid pump.

[0049] In one embodiment, referring to Figure 1 , the soaking container 5 is provided with a rock sample support assembly 10 for fixing the first rock sample 12 and / or the second rock sample 13 in the middle of the cavity of the soaking container 5. The rock sample to be measured is fixed in the middle of the cavity of the soaking container 5 through the rock sample support assembly 10, so as to ensure the stability of the rock during soaking, avoid direct contact between the rock sample and the container wall, ensure that the rock sample can be fully wrapped and soaked by the drilling fluid, improve the soaking effect, and ensure the accuracy of the subsequent friction coefficient measurement.

[0050] The soaking unit is a rock sample processing unit that simulates the action of drilling fluid on rocks during the drilling process. The soaked rock sample enters the detection unit for dynamic detection to facilitate obtaining the friction coefficient of the soaked rock sample. The detection unit includes a loading part and a displacement driving part. Among them, the loading part can include the above-mentioned loading mechanism 1 and the load detection device 3. Specifically, referring to Figure 3, the loading mechanism 1 includes a gantry 101 and a loading pressure rod 102. The loading pressure rod 102 is vertically suspended from the crossbeam of the gantry 101. The first rock sample 12 and the second rock sample 13 stacked one above the other are placed below the crossbeam. When applying a load, the loading pressure rod 102 can move downward relative to the crossbeam of the gantry 101 until the bottom of the loading pressure rod 102 is in press contact with the top surface of the first rock sample 12, so as to apply a certain static pressure to the first rock sample 12. After the test is completed, by adjusting the loading pressure rod 102 to move upward relative to the crossbeam of the gantry 101, the loading pressure rod 102 can be separated from the first rock sample 12, facilitating the removal of the first rock sample 12 and the second rock sample 13.

[0051] It should be noted that, in order to accurately measure the friction coefficient between the first rock sample 12 and the second rock sample 13, the load applied by the loading pressure rod 102 to the first rock sample 12 should be perpendicular to the contact surface between the first rock sample 12 and the second rock sample 13. In this embodiment, the contact surface between the first rock sample 12 and the second rock sample 13 is arranged parallel to the horizontal plane, and the loading pressure rod 102 applies a vertical load to the first rock sample 12.

[0052] When sliding friction occurs between the second rock sample 13 and the first rock sample 12, in order to enable the friction force detection device 4 to measure the friction force received by the first rock sample 12, the lateral force between the loading pressure rod 102 and the crossbeam of the gantry 101 should be negligible. For this purpose, the crossbeam of the gantry 101 may be provided with a non-blocking slide rail 103 and a slider 104 that forms a sliding fit with the non-blocking slide rail 103. The loading pressure rod 102 is fixedly connected to the slider 104. Thus, the loading pressure rod 102 can slide unobstructedly on the non-blocking slide rail 103, so that the friction force between the loading pressure rod 102 and the crossbeam can be ignored. Preferably, the non-blocking slide rail 103 is arranged parallel to the contact surface between the first rock sample 12 and the second rock sample 13.

[0053] In this embodiment, the friction force detection device 4 can be arranged on the vertical rod of the gantry 101. In other words, the vertical rod can play the role of bearing the gravity of the friction force detection device 4. Further, after using the loading pressure rod 102 to press the first rock sample 12 and the second rock sample 13, the detection end of the friction force detection device 4 can be docked to the first rock sample 12, so that the friction force detection device 4 can only receive the friction force applied by the second rock sample 13 to the first rock sample 12 and the reaction force applied by the vertical rod in the lateral direction, thereby accurately measuring the specific value of the friction force.

[0054] The structure form of the friction force detection device 4 is not limited in this application. To reduce the equipment cost, a conventional force sensor (such as a strain gauge type force sensor) can be selected as the friction force detection device 4 of this application.

[0055] In addition, the present application does not limit the driving mode of the loading pressure rod 102, which can be manual, semi-automatic or fully automatic. Figure 3 , the loading rod 102 is formed as a manually rotatable screw rod, and accordingly, the slider 104 is provided with a screw hole matching therewith, and the loading rod 102 passes through the screw hole and forms a threaded connection with the screw hole, so that the applied load of the loading rod 102 can be adjusted by manually twisting the loading rod 102. In some other embodiments, a loading cylinder can be used as the loading mechanism 1, wherein the cylinder barrel of the loading cylinder is fixed on the slider 104, and the loading rod 102 is the piston rod of the loading cylinder, so that the loading rod 102 can be semi-automatically or fully automatically driven to perform a loading action in the form of liquid drive. Of course, the loading mechanism 1 can also be a driving mechanism such as a cylinder or an electric push rod, which is not limited in comparison in this application.

[0056] like Figure 3 As shown, the load detection device 3 can be arranged in the loading rod 102. When the loading rod 102 performs a loading action, the load first acts on the load detection device 3 and then is transmitted to the first rock sample 12, so that the applied load value can be accurately measured. Of course, when the loading mechanism 1 is a driving mechanism such as an oil cylinder or an air cylinder, the load detection device 3 can be a pressure sensor built into the cylinder.

[0057] In order to satisfy that the force applied by the second rock sample 13 to the first rock sample 12 during movement is only sliding friction, the pulling force or pushing force applied by the displacement driving mechanism 2 to the second rock sample 13 must be parallel to the contact surface between the first rock sample 12 and the second rock sample 13. For example, the displacement driving mechanism 2 can be formed as a linear driving mechanism, and is arranged to extend in a direction parallel to the contact surface between the first rock sample 12 and the second rock sample 13. In this way, the displacement driving mechanism 2 can satisfy that the displacement driving mechanism 2 only applies a pulling force or pushing force parallel to the contact surface between the first rock sample 12 and the second rock sample 13 to the second rock sample 13, avoiding the generation of component forces and affecting the accuracy of dynamic detection. For example, when the displacement driving mechanism 2 pulls the second rock sample 13 obliquely upward, it will generate components in the horizontal and vertical directions, wherein the vertical component force, when acting on the first rock sample 12, will affect the detection result of the load detection device 3.

[0058] In this embodiment, the displacement drive mechanism 2 can be arranged on the vertical pole of the gantry 101, so as to simplify the structure and reduce the space occupied by the mechanism. The displacement drive mechanism 2 can be a screw mechanism, a hydraulic cylinder, a pneumatic cylinder, a linear motor, an electric push rod, etc. The specific form of the displacement drive mechanism 2 is not limited in this application.

[0059] For the calculation of the friction coefficient of the rock sample, it can be achieved with the help of the data processing device 11 in the measurement of the rock friction coefficient. Specifically, the data processing device 11 communicates with the load detection device 3 and the friction force detection device 4 respectively, and is configured to determine that the second rock sample 13 moves relative to the first rock sample 12 when it is judged that the floating value of the friction force is within the preset allowable floating range, and calculate the accurate rock friction coefficient according to the real-time load and friction force data and the rock friction coefficient calculation formula described above. Among them, the data processing device 11 may include a data acquisition card and a computer connected to the data acquisition card. The data acquisition card is used to collect the data signals output by the load detection device 3 and the friction force detection device 4 and transmit the data to the computer. The computer is installed with data processing software for processing and analyzing the collected data to obtain the rock friction coefficient. In addition, the computer may also be provided with a visualization interface to display the detection data, the friction coefficient curve and the experimental results in real time through the visualization interface, which is convenient for users to observe and analyze.

[0060] Of course, in the case of full manual control or semi-automatic control, the load data and the friction force data can also be visually observed and recorded manually and then analyzed and calculated manually. Obviously, through the communication and cooperation between the data processing device 11, the load detection device 3 and the friction force detection device 4 for judgment, processing, analysis and calculation, the accuracy is higher, the operation is simpler, the automation degree is higher, and the efficiency is better.

[0061] In the description of the present application, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0062] In the present application, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0063] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0064] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. Rock friction coefficient measurement system, characterized in that: include: A soaking unit, used to simulate downhole drilling fluid to soak the first rock sample (12) and the second rock sample (13); and The detection unit comprises a loading mechanism (1), a displacement driving mechanism (2), a load detection device (3) and a friction force detection device (4), wherein the loading mechanism (1) is used to apply a load to the first rock sample (12) and the second rock sample (13) which are sequentially stacked one above the other after immersion, the displacement driving mechanism (2) is used to drive the second rock sample (13) to move relative to the first rock sample (12), the load detection device (3) is used to detect the load applied by the loading mechanism (1), and the friction force detection device (4) is used to detect the friction force applied by the second rock sample (13) on the first rock sample (12).

2. The rock friction coefficient measurement system according to claim 1, characterized in that: The immersion unit comprises a immersion container (5), a heating device (6) and a liquid supply mechanism (7); the immersion container (5) is used to contain the first rock sample (12) and / or the second rock sample (13); the liquid supply mechanism (7) is used to input drilling fluid into the immersion container (5); and the heating device (6) is used to heat the drilling fluid in the immersion container (5).

3. The rock friction coefficient measurement system according to claim 2, characterized in that: The immersion unit further comprises a pressure detection device (8) and a temperature detection device (9), wherein the pressure detection device (8) and the temperature detection device (9) are used to detect the hydraulic pressure and the temperature of the drilling fluid in the immersion container (5), respectively.

4. The rock friction coefficient measurement system according to claim 3, characterized in that: The liquid supply mechanism (7) comprises a liquid pump (701) and a pressure control device (702), wherein the liquid pump (701) is connected to the immersion container (5) via a pipeline, and the pressure control device (702) is arranged in the pipeline and is used to control the hydraulic pressure of the drilling fluid input into the immersion container (5); And / or, the heating device (6) is provided with a temperature controller (601) for controlling the heating temperature.

5. The rock friction coefficient measurement system according to claim 2, characterized in that: The immersion container (5) is provided with a rock sample support assembly (10) for fixing the first rock sample (12) and / or the second rock sample (13) in the middle of the cavity of the immersion container (5).

6. The rock friction coefficient measurement system according to claim 1, characterized in that: The loading mechanism (1) comprises a gantry (101) and a loading pressure rod (102); the loading pressure rod (102) is vertically suspended from a crossbeam of the gantry (101) and is used for press-connecting with the first rock sample (12).

7. The rock friction coefficient measurement system according to claim 6, characterized in that: The cross beam of the gantry (101) is provided with a non-blocking slide rail (103) and a slider (104) that forms a sliding connection with the non-blocking slide rail (103); the loading pressure rod (102) is fixedly connected to the slider (104); and the friction force detection device (4) is used to be connected between the vertical rod of the gantry (101) and the first rock sample (12).

8. The rock friction coefficient measurement system according to claim 7, characterized in that: The slider (104) is provided with a screw hole, and the loading pressure rod (102) is formed as a screw rod passing through the screw hole and forming a threaded connection with the screw hole; Alternatively, the loading mechanism (1) comprises a loading cylinder fixedly connected to the slider (104), and the loading pressure rod (102) is a piston rod of the loading cylinder.

9. The rock friction coefficient measurement system according to claim 6, characterized in that: The displacement drive mechanism (2) is arranged on the vertical pole of the gantry (101) and is formed as a linear drive mechanism.

10. The rock friction coefficient measurement system according to any one of claims 1 to 9, characterized in that: The rock friction coefficient measurement system also includes a data processing device (11), which communicates with the load detection device (3) and the friction force detection device (4) respectively, and is configured to determine that the second rock sample (13) moves relative to the first rock sample (12) when it is determined that the floating value of the friction force is within a preset allowable floating range, and calculate the rock friction coefficient based on the real-time load and friction force.

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