Simulation experiment device for sliding friction characteristic of weak surface of shale
By designing an experimental device to simulate the sliding friction characteristics of shale weak surfaces, and using a heating furnace and a silicon controlled rectifier circuit to simulate in-situ stress and pore pressure, the problem of casing deformation caused by shale weak surface slippage was solved, thus improving the efficiency of shale oil and gas resource development.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NORTH CHINA INSTITUTE OF SCIENCE & TECHNOLOGY (NATIONAL SAFETY TRAINING CENTER OF COAL MINES)
- Filing Date
- 2025-04-11
- Publication Date
- 2026-05-12
AI Technical Summary
In shale gas development, slippage of weak surfaces in shale leads to severe casing deformation, affecting fracturing effectiveness and restricting the development of shale oil and gas resources.
Design an experimental device to simulate the sliding friction characteristics of weak surfaces of shale, including a heating furnace, experimental shale, pressure sensor, temperature sensor and displacement sensor. Temperature control is achieved through an electric heating wire and a silicon controlled rectifier (SCR) control circuit. Combined with a pressure application mechanism, the device simulates in-situ stress and pore pressure to monitor the sliding friction characteristics of weak surfaces of shale.
It has achieved accurate simulation of the sliding friction characteristics of weak surfaces in shale, provided experimental means to study the slip of weak surfaces in shale, helped solve the problem of casing deformation, and improved the development efficiency of shale oil and gas resources.
Smart Images
Figure CN224231589U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a shale weak surface sliding friction characteristic simulation experiment device. BACKGROUND
[0002] In shale gas development, the problem of casing deformation caused by shale weak surface sliding seriously affects the fracturing effect. In view of the characteristics of extremely low permeability and low porosity of shale reservoir, horizontal well and volume fracturing construction methods are needed during development. With the large-scale volume fracturing construction of each shale oil and gas field, if the area where the reservoir is located is in a high stress difference environment, geological movement is frequent, and bedding, lithologic interface, natural fracture and fault are developed. In the hydraulic fracturing process of shale gas horizontal well, the fracturing fluid pumped into the shale weak surface causes uneven shear stress field in the reservoir, the net pressure in the fracture increases, the weak surface is activated, and the casing deformation caused by weak surface sliding occurs frequently, which leads to the frequent phenomenon that the bridge plug cannot be lowered to the specified position. The problem of formation shear sliding in the volume fracturing construction of shale reservoir seriously affects the construction and production on site, and has become a bottleneck restricting the development of shale oil and gas resources, so it is necessary to study the shale weak surface sliding. SUMMARY
[0003] In view of the above problems, the purpose of the utility model is to provide a shale weak surface sliding friction characteristic simulation experiment device.
[0004] In order to achieve the above purpose, the scheme of the utility model is:
[0005] A shale weak surface sliding friction characteristic simulation experiment device, including a heating furnace, experimental shale and experimental analysis computer, the experimental shale is composed of two shale blocks stacked on top of each other, the stacked surface is the inclined surface of the simulated weak surface, a liquid supply hole is provided on the upper shale block, the liquid supply hole reaches the inclined surface, an electric heating wire is provided in the heating furnace, and the electric heating wire is connected to the temperature control circuit of the experimental analysis computer, wherein: the heating furnace includes a closed metal cylinder, an electrically insulated heat insulation layer is arranged around the sidewall in the closed metal cylinder, the electrically insulated heat insulation layer wraps a heating cylinder, inwardly tapered upper and lower portions are arranged on the heating cylinder, the electric heating wire is wound around the inner sidewall of the heating cylinder, a plastic positioning sleeve is arranged in the heating cylinder close to the upper and lower tapered portions, the plastic positioning sleeve is seated on the bottom plate of the closed metal cylinder, a powdery heat-conducting material is filled between the plastic positioning sleeve and the inner sidewall and the upper and lower tapered portions of the heating cylinder, the experimental shale is placed in the middle section of the plastic positioning sleeve, an upper pressing column and a lower pressing column are respectively arranged on the upper and lower end surfaces of the experimental shale in the plastic positioning sleeve, the lower pressing column is seated on the bottom plate of the closed metal cylinder, a pressing column is arranged between the upper pressing column arranged on the upper end surface of the experimental shale and the top cover of the closed metal cylinder, a pressing mechanism is arranged on the top cover of the closed metal cylinder, a pressing rod of the pressing mechanism is placed on the pressing column, a liquid supply channel is arranged on the upper pressing column, a lower end port of the liquid supply channel is communicated with the liquid supply hole on the experimental shale, an upper end port of the liquid supply channel is connected to a liquid supply pressure pump through a pipeline penetrating through the top cover of the closed metal cylinder, a pressure sensor, a temperature sensor and a displacement sensor are arranged on the inclined surface of the experimental shale, signal lines of the pressure sensor, the temperature sensor and the displacement sensor are led out through channels arranged on the upper pressing column and the pressing column, and the led-out signal lines are connected to the experimental analysis computer through the top cover of the closed metal cylinder.
[0006] Further, the powdery heat-conducting material is boron nitride powder.
[0007] Further, the pressing mechanism includes nuts symmetrically welded and fixed on the center of the upper end surface of the top cover of the closed metal cylinder, a screw is screwed on the nut, and the screw serves as an adjustable pressing rod placed on the pressing column.
[0008] Further, the plastic positioning sleeve is a plastic sleeve or a copper pipe sleeve.
[0009] The scheme further comprises: the temperature control circuit comprises a controllable switch, the electric heating wire is connected with an AC power supply through the controllable switch, the controllable switch comprises a full-wave rectifier circuit, and the AC power supply forms a loop through the electric heating wire and the full-wave rectifier circuit; the AC input of the full-wave rectifier circuit is connected in series with the electric heating wire, the DC positive output of the full-wave rectifier circuit is connected with the positive pole of a thyristor, the negative pole of the thyristor is connected with the DC negative output of the full-wave rectifier circuit, the control pole of the thyristor is connected with a temperature sensing circuit, the temperature sensor is connected with the temperature sensing circuit, and the temperature sensing circuit controls the control pole of the thyristor to be high or low according to a set temperature; when the control pole is high, the thyristor is turned on, and when the control pole is low, the thyristor is turned off.
[0010] When the thyristor is turned on, the positive and negative outputs of the full-wave rectifier circuit are short-circuited, and the AC power supply is connected with the electric heating wire through the full-wave rectifier circuit to heat.
[0011] When the thyristor is turned off, the positive and negative outputs of the full-wave rectifier circuit are disconnected, and the AC power supply is disconnected with the electric heating wire through the full-wave rectifier circuit.
[0012] The shale weak surface sliding friction characteristic simulation experiment device has the advantages that the device can conveniently realize shale weak surface sliding friction characteristic simulation experiment, the temperature control circuit of the device adopts the DC output of the full-wave rectifier circuit to connect the thyristor as a switch, and the circuit control is simple and reliable.
[0013] The utility model will be described in detail below in combination with the drawings and embodiments. DRAWINGS
[0014] Figure 1 It is the structural schematic diagram of the utility model;
[0015] Figure 2 It is the temperature control circuit schematic diagram of the utility model. EMBODIMENT
[0016] A shale weak surface sliding friction characteristic simulation experiment device, as shown in Figure 1As shown, the experimental device comprises a heating furnace 1, experimental shale 2 and experimental analysis computer 3, the experimental shale 2 is composed of two shale blocks stacked together, the stacked surface is a simulated weak surface inclined surface 201, a liquid supply hole 202 is arranged on the upper shale block, the liquid supply hole directly reaches the inclined surface 201, the heating furnace 1 is provided with an electric heating wire 101, the electric heating wire 101 is connected to the temperature control circuit 301 of the experimental analysis computer 3, wherein: the heating furnace 1 comprises a closed metal cylinder 102, an electrically insulated heat insulation layer 103, such as an asbestos layer, is arranged around the side wall in the closed metal cylinder, the electrically insulated heat insulation layer 103 wraps a heating cylinder 104, the heating cylinder 104 is provided with inwardly tapered upper and lower tapering portions 104-1, the electric heating wire 101 is wound around the inner side wall of the heating cylinder 104, a plastic positioning sleeve 105 is arranged in the heating cylinder 104 and closely contacts the upper and lower tapering portions 104-1, the plastic positioning sleeve 105 is a plastic sleeve or a copper pipe sleeve, in order to adapt to the dislocation deformation of the experimental shale 2 after being pressed in the plastic positioning sleeve 105. The plastic positioning sleeve 105 is seated on the bottom plate 102-1 of the closed metal cylinder 102, and a powdery heat-conducting material 106, which is boron nitride powder, is filled between the plastic positioning sleeve 105 and the inner side wall of the heating cylinder 104 and the upper and lower tapering portions 104-1. The experimental shale 2 is placed in the middle segment of the plastic positioning sleeve 105, the upper and lower ends of the experimental shale 2 are respectively provided with an upper pressing column 4 and a lower pressing column 5 in the plastic positioning sleeve 105, the lower pressing column 5 is seated on the bottom plate 102-1 of the closed metal cylinder, a pressing column 6 is arranged between the upper pressing column 4 arranged on the upper end surface of the experimental shale 2 and the top cover 102-2 of the closed metal cylinder, a pressing mechanism is arranged on the top cover 102-2 of the closed metal cylinder, a pressing rod of the pressing mechanism is placed on the pressing column 6, a liquid supply channel 401 is arranged on the upper pressing column 4, a lower end of the liquid supply channel 401 is connected to the liquid supply hole 202 on the experimental shale 2, an upper end of the liquid supply channel 401 is connected to a liquid pressure pump 8 through a pipeline 7 penetrating through the top cover 102-2 of the closed metal cylinder, a pressure sensor 9, a temperature sensor 10 and a displacement sensor 11 are arranged on the inclined surface 201 of the experimental shale 2, signal lines of the pressure sensor 9, the temperature sensor 10 and the displacement sensor 11 are led out through channels arranged on the upper pressing column 4 and the pressing column 6, and the led-out signal lines are connected to the experimental analysis computer 3 through the top cover 102-2 of the closed metal cylinder.
[0017] Wherein: the pressing mechanism can use the telescopic arm of the hydraulic cylinder to press on the pressing column 6 to achieve motorized control, in order to reduce the complexity of the design, the embodiment adopts manual adjustment control, the pressing mechanism comprises two symmetrically welded nuts 12 on the center of the upper end surface of the closed metal cylinder, a screw rod 13 is screwed on the nut 12, and the screw rod 13 serves as an adjustable pressing rod to press on the pressing column 6. The pressure adjustment and control of the experimental shale 2 are realized by adjusting the screw rod 13.
[0018] In this embodiment: the temperature control circuit 301 uses silicon controlled rectifier (SCR) control, such as... Figure 2 As shown, the device includes a controllable switch 301-1. The electric heating wire 101 is connected to an AC power supply via the controllable switch. The controllable switch 301-1 includes a full-wave rectifier circuit D1-D5. The AC power supply forms a circuit through the electric heating wire 101 and the full-wave rectifier circuit D1-D5. The AC input of the full-wave rectifier circuit D1-D5 is connected in series with the electric heating wire 101. The DC positive output of the full-wave rectifier circuit D1-D5 is connected to the positive terminal of a silicon controlled rectifier (SCR). The negative terminal of the SCR is connected to the DC negative output of the full-wave rectifier circuit D1-D5. The control terminal of the SCR is connected to a temperature sensing circuit 301-2. The temperature sensor 10 is connected to the temperature sensing circuit 301-2. The temperature sensing circuit 301-2 controls the control terminal of the SCR to be at a high or low potential according to the set temperature. When the control terminal is at a high potential, the SCR is turned on; when the control terminal is at a low potential, the SCR is turned off.
[0019] When the SCR is turned on, the positive and negative outputs of the full-wave rectifier circuit D1-D5 are short-circuited, and the AC power supply is connected to the electric heating wire 101 for heating through the full-wave rectifier circuit D1-D5.
[0020] When the SCR is turned off, the positive and negative outputs of the full-wave rectifier circuit D1-D5 are disconnected, and the AC power supply is disconnected from the heating wire 101 by the full-wave rectifier circuit D1-D5.
[0021] The temperature sensing circuit 301-2 is as follows: Figure 2 As shown, a 555 timer IC is included. Temperature sensors 10 are connected between pins 6 and 2 of the 555 timer IC, and between pin 2 and the DC negative output of the full-wave rectifier circuits D1-D5. Each temperature sensor 10 includes two resistors, R6 and R7, representing two temperature sensors 10 located at different positions. An adjustable potentiometer W1 is connected between pin 6 and the power supply VDD. The adjustable potentiometer W1 is used to set the initial temperature. The 555 timer IC and resistors R5 and R7... W1 and R6 form a bistable trigger. The DC power supply VDD is formed by half-wave rectification of the AC power supply through diode D1, resistor R1, and LED. The voltage regulation of the half-wave rectification is composed of Zener diode DZ1 and filter capacitor C1, forming a 5V DC power supply VDD. Pin 3 of the 555 timer IC is connected to the base of transistor BG1 through inverter Q and resistor R3. The collector of transistor BG1 is connected to the power supply VDD, and the emitter of transistor BG1 is connected to the control terminal of the SCR. D7, transistor BG2, and resistor R4 form the SCR overvoltage protection circuit.
[0022] When the temperature increases beyond the set value, the resistance of the corresponding temperature sensor resistor R6, R7 becomes smaller, the IC is set due to the 2 feet potential drop to less than 1 / 3 VDD and the 3 feet output of the 555 time base circuit IC is low through the inverter Q to the control electrode of the thyristor SCR, so that the thyristor AC zero voltage switch composed of D2~D5, SCR, BG1, BG2, etc. is disconnected, and the electric heating wire 101 is powered off;
[0023] When the temperature drops and needs to be heated, the resistance of the corresponding temperature sensor resistor R7, R6 becomes larger, the 2 feet potential of the 555 time base circuit IC rises to more than 1 / 3 VDD and is reset, the 3 feet output of the 555 time base circuit IC is low through the inverter Q to the control electrode of the thyristor SCR, so that the thyristor AC zero voltage switch is turned on, and the electric heating wire 101 is connected to the power supply.
[0024] During debugging, the temperature point can be set as needed. When the temperature is higher than the set temperature, the electric heating wire 101 automatically cuts off the power supply; when the temperature is lower than the set temperature, the electric heating wire 101 automatically connects the power supply. The potentiometer W1 is a temperature adjusting potentiometer, and the corresponding temperature can be marked on the dial for easy use.
[0025] Through this embodiment, the in-situ temperature of the reservoir can be simulated; the experimental shale 2 is supplied with liquid through the liquid supply pressure pump 8 to simulate the pore pressure; the pressure applying mechanism applies pressure to simulate the ground stress, and by changing these parameters and the inclination angle of the experimental shale 2, different reservoir conditions can be simulated. The shear displacement and shear rate of the experimental shale 2 are monitored, and according to these data and the pressure applied by the pressure applying mechanism, the sliding friction coefficient change and the critical sliding water pressure are calculated to study the sliding friction characteristics of the shale weak plane.
Claims
1. An experimental apparatus for simulating the sliding friction characteristics of a weak surface of shale, comprising a heating furnace (1), an experimental shale (2), and an experimental analysis computer (3), wherein the experimental shale is composed of two stacked shale blocks, the stacked surface being an inclined plane (201) simulating a weak surface, a liquid supply hole (202) is provided on the upper shale block, the liquid supply hole reaching directly to the inclined plane (201), an electric heating wire (101) is provided in the heating furnace (1), the electric heating wire (101) is connected to the temperature control circuit (301) of the experimental analysis computer (3), characterized in that, The heating furnace (1) includes a closed metal cylinder (102). An electrically insulating heat insulation layer (103) is arranged around the side wall inside the closed metal cylinder. The electrically insulating heat insulation layer (103) wraps around a heating cylinder (104). The heating cylinder (104) has inwardly tapered openings (104-1) at the top and bottom. The electric heating wire (101) is wound around the inner side wall of the heating cylinder (104). A malleable positioning sleeve (105) is arranged inside the heating cylinder (104) close to the top and bottom tapered openings. (105) The experimental shale (2) is placed on the bottom plate (102-1) of the closed metal cylinder (102). Powdered thermally conductive material (106) is filled between the plastic positioning sleeve (105) and the inner wall of the heating cylinder (104) and the upper and lower openings (104-1). The experimental shale (2) is placed in the middle section of the plastic positioning sleeve (105). The upper pressure column (4) and the lower pressure column (5) are respectively set on the upper and lower end faces of the experimental shale (2) in the plastic positioning sleeve (105). The lower pressure column (5) sits on the bottom plate of the closed metal cylinder. On (102-1), a pressure column (6) is provided between the upper pressure column (4) on the upper end face of the experimental shale (2) and the closed metal cylinder top cover (102-2). A pressure mechanism is provided on the closed metal cylinder top cover (102-2), and the pressure rod of the pressure mechanism rests on the pressure column (6). A liquid supply channel (401) is provided on the upper pressure column (4). The lower end of the liquid supply channel (401) is connected to the liquid supply hole (202) on the experimental shale (2), and the upper end of the liquid supply channel (401) is connected to the pipe ( 7) Connect the liquid supply pressure pump (8) through the closed metal cylinder top cover (102-2). A pressure sensor (9), a temperature sensor (10) and a displacement sensor (11) are set on the inclined surface (201) of the experimental shale (2). The signal lines of the pressure sensor (9), temperature sensor (10) and displacement sensor (11) are led out through the channels set on the upper pressure column (4) and the pressure column (6). The led-out signal lines are connected to the experimental analysis computer (3) through the closed metal cylinder top cover (102-2).
2. The experimental apparatus according to claim 1, characterized in that, The powdered thermally conductive material (106) is boron nitride powder.
3. The experimental apparatus according to claim 1, characterized in that, The pressure-applying mechanism includes nuts (12) that are symmetrically welded and fixed on both sides of the center of the upper end face of the closed metal cylindrical top cover. A screw (13) is screwed on the nut (12), and the screw (13) serves as an adjustable pressure-applying rod that rests on the pressure-applying column (6).
4. The experimental apparatus according to claim 1, characterized in that, The malleable positioning sleeve (105) is a plastic sleeve or a copper tube sleeve.
5. The experimental apparatus according to claim 1, characterized in that, The temperature control circuit (301) includes a controllable switch (301-1). The electric heating wire (101) is connected to an AC power supply via the controllable switch. The controllable switch (301-1) includes a full-wave rectifier circuit (D1-D5). The AC power supply forms a loop through the electric heating wire (101) and the full-wave rectifier circuit (D1-D5). The AC input of the full-wave rectifier circuit (D1-D5) is connected in series with the electric heating wire (101), and the DC input of the full-wave rectifier circuit (D1-D5) is connected in series with the electric heating wire (101). The positive output is connected to the positive terminal of a silicon controlled rectifier (SCR), the negative terminal of the SCR is connected to the DC negative output of the full-wave rectifier circuit (D1-D5), the control terminal of the SCR is connected to a temperature sensing circuit (301-2), the temperature sensor (10) is connected to the temperature sensing circuit, and the temperature sensing circuit controls the control terminal of the SCR to be at a high potential or a low potential according to the set temperature. When the control terminal is at a high potential, the SCR is turned on, and when the control terminal is at a low potential, the SCR is turned off. When the silicon controlled rectifier (SCR) is turned on, the positive and negative outputs of the full-wave rectifier circuit (D1-D5) are short-circuited, and the AC power supply is connected to the electric heating wire (101) for heating through the full-wave rectifier circuit (D1-D5). When the silicon controlled rectifier (SCR) is turned off, the positive and negative outputs of the full-wave rectifier circuit (D1-D5) are disconnected, and the AC power supply and the electric heating wire (101) are disconnected by the full-wave rectifier circuit (D1-D5).