CN-116593525-B - Core holder for thermal stress fracture experiment and experiment method

Abstract

The invention discloses a core holder for thermal stress fracture experiments and an experimental method, wherein the core holder comprises a thermal insulation pipeline sleeve, a heating device is arranged at one end of the thermal insulation pipeline sleeve, a thermal insulation layer is arranged in an area, outside the heating device, of the thermal insulation pipeline sleeve, a first temperature sensor is arranged on the upper side of the opposite area of the thermal insulation layer, a transparent glass fiber reinforced plastic container is arranged on the lower side of the opposite area of the thermal insulation layer, a second temperature sensor is arranged on the heating device, a clamping device is used for clamping the thermal insulation pipeline sleeve, a piston sleeve is arranged on the clamping device and used for introducing gas or liquid into the cavity of the thermal insulation pipeline sleeve, and an experimental core placed in the cavity of the thermal insulation pipeline sleeve is clamped. Besides the thermal stress fracture displacement experiment, the experimental device can meet the equipment requirement of the conventional body experiment, and has strong functionality.

Inventors

• CHEN XIYU
• LI JINGZE
• Chang Tai
• CHEN GUOQI

Assignees

• 西南石油大学

Dates

Publication Date

20260505

Application Date

20230413

Claims (5)

1. 1. A core holder for thermal stress fracturing experiments, comprising: A thermal insulation tubing kit having a through cavity; the device comprises a heat-insulating pipeline sleeve, a heating device, a first temperature sensor, a transparent glass steel hiding container, a second temperature sensor, a first temperature sensor, a second temperature sensor and a third temperature sensor, wherein the heating device is arranged at one end of the heat-insulating pipeline sleeve; The clamping device is used for clamping the heat-insulating pipeline suite; The device comprises a clamping device, a piston sleeve, an experimental rock core, a clamping device and a control device, wherein the clamping device is used for clamping an experimental rock core placed in a cavity of the thermal insulation pipeline sleeve; the heat preservation pipeline suite comprises two concentric pipelines which are mutually sleeved, a heat preservation layer is filled between the two concentric pipelines, and a reinforced heat conduction copper pipe is filled between the two concentric pipelines, wherein the right end of the heat preservation pipeline is wrapped by the heating device; A plurality of mounting holes are drilled above and below the two concentric pipelines, the first temperature sensor is positioned in the mounting hole above the concentric pipeline, and the transparent glass fiber reinforced plastic container is positioned in the mounting hole below the concentric pipeline; The heating device is an elliptical concentric copper pipe with an interlayer, a heating resistor is wound in the interlayer, the second temperature sensor is arranged above the right elliptical concentric copper pipe, and a connecting electric head is arranged below the elliptical concentric copper pipe; the clamping device comprises a glass frame and sleeves, wherein the two sleeves are respectively arranged at the left side and the right side of the frame and are symmetrically arranged in an axis, grooves are formed in the left side and the right side of the sleeves respectively, the diameter of the grooves of the sleeves at the left side is smaller than that of the grooves of the sleeves at the right side, and the heat-insulating pipeline sleeve is clamped through the grooves of the two sleeves at the left side and the right side; The piston sleeve comprises a piston, a piston cap, a piston rod and a piston top sheet, wherein the piston and the piston cap are provided with a pair and are symmetrical along the diagonal line of a glass frame, the piston cap is respectively embedded in a groove of the sleeve, one end of the piston rod is connected with the piston top sheet, the other end of the piston rod penetrates through the left sleeve and is connected with the left piston, two ends of an elliptical concentric copper pipe vertically penetrate through the piston cap embedded on the sleeve and are vertically embedded in a concentric pipeline, a horizontal through hole is arranged in the middle of the piston along the horizontal direction and penetrates through the piston rod and the piston top sheet, a liquid inlet/gas inlet is arranged on the left side of the piston and is vertical to the horizontal through hole, a liquid outlet/gas inlet is arranged at one end of the right piston fixed by a compression screw and penetrates through the right sleeve and is arranged in the cavity, the liquid outlet/gas outlet is vertical to the horizontal through hole, and the liquid inlet and the liquid outlet/gas outlet are both provided with matched plugs and gas and liquid sharing quick connectors.
2. 2. The core holder for thermal stress cracking experiments according to claim 1, wherein the glass frame is cuboid, grooves are formed in the front and the back of the glass frame and used for installing observation glass, prefabricated pore channels are formed in the left and the right bottoms of the glass frame, clamping grooves are formed in the bottoms of the glass frame, liquid/gas channels are formed in the two sides of the glass frame, and the liquid/gas channels are flush with the middle parts of the piston rod and the concentric pipelines.
3. 3. The core holder for thermal stress cracking experiments according to claim 2, wherein the clamping device further comprises a T-shaped pipe sleeve, the T-shaped pipe sleeve is located at one end of the right side of the glass frame, threaded holes are formed in four sides of the T-shaped pipe sleeve, the T-shaped plate is fixed through tightening screws, an oval pore canal is formed in the middle of the T-shaped plate, a silica gel pad is arranged in the oval pore canal and is larger than a right side piston, and the right side piston vertically penetrates through the oval pore canal of the T-shaped plate and is fixed in position.
4. 4. The core holder for thermal stress cracking experiments according to claim 3, wherein the clamping device further comprises a U-shaped square clamp, the U-shaped square clamp is located at one end of the left piston, threaded holes are formed in two ends of the U-shaped square clamp and are vertically placed in clamping grooves in the glass frame, the U-shaped square clamp is fixed to the glass frame through tightening screws, and the inner side of the U-shaped square clamp is tightly attached to the left piston.
5. 5. An experimental method of a core holder for thermal stress cracking experiments, which is realized by adopting the core holder for thermal stress cracking experiments as claimed in claim 4, and is characterized by comprising the following steps: 1) Assembling a piston rod and a piston top sheet, penetrating the piston cap, putting the piston cap with the piston rod into a groove of a pipe sleeve on the left side of the glass frame, pressing to enable the piston cap to be tightly attached, putting the other piston cap into a groove of a pipe sleeve on the right side of the glass frame, and pressing to enable the piston cap to be tightly attached; 2) Combining a piston with a horizontal fluid channel and a liquid/gas inlet with a U-shaped square clamp, inserting the piston rod combined in the step 1 into the piston, then placing two ends of the U-shaped square clamp into a clamping groove of a glass frame, tightening a screw to fix the left-side piston, placing a T-shaped pipe sleeve into the clamping groove of the glass frame through a compression bracket, and connecting and fixing the T-shaped pipe sleeve on the glass frame through the screw; 3) Sleeving a heating device on a part without an insulating layer on the right side of the insulating pipeline sleeve, and placing the dried experimental rock core from the right side of the pipeline; 4) Connecting a power supply, a temperature control device, a temperature sensor, a heat transfer resistor of a recording computer of the temperature sensor and sensor wires with a heat-insulating pipeline sleeve and a heating device by penetrating through prefabricated pore channels of a frame; 5) Placing an observation light source in a frame light source placing clamping groove of the frame; 6) Pumping nitrogen into the liquid/gas inlet by using the quick connector, pulling out a plug of the liquid/gas outlet, and exhausting the rest gas in the clamp holder; 7) After the gas is drained, a power supply of a heating device is turned on, the temperature of an initial rock core of an experiment is set, and when the temperature of all the first temperature sensors at the rock core position on the heat preservation pipeline and the temperature of the second temperature sensors on the heating device are the same as the set temperature of the initial rock core of the experiment, the current time is recorded; 8) Pulling out plugs of the liquid inlet/gas outlet and the liquid outlet/gas outlet, pumping experimental liquid into the liquid inlet/gas outlet by using a quick connector, wherein the temperature of the experimental liquid is obviously lower than the temperature of an initial core of the experiment, and recording the time of starting to change the first temperature of all first temperature sensors at the position of the core, the time of first liquid appearance of a transparent glass steel container and the flow rate of the liquid outlet/gas outlet; 9) When the second temperature sensor generates temperature change for the first time, the power supply is turned off; 10 Step 1-9 is carried out on the rock core with the same block and size as the rock core in the step 1-9 without heating, and the time of the first appearance of the liquid and the flow rate of the liquid outlet/gas port of the transparent glass fiber reinforced plastic container are recorded; 11 End of the experiment.

Description

Core holder for thermal stress fracture experiment and experiment method Technical Field The invention relates to the technical field of oil and gas field development, in particular to a core holder for thermal stress fracturing experiments and an experimental method. Background The deep shale gas is different from the shallow shale gas development in a series of engineering technical problems such as more difficult construction of artificial cracks, insufficient permeability increasing capability of a conventional crack network system, accelerated decrease of productivity after pressing and the like due to the problems of high temperature, high pressure, underdevelopment of natural cracks, obvious difference of horizontal main stress and the like caused by deep reservoir burial. Therefore, the development effect of the deep shale gas is not ideal, and the return on investment is obviously insufficient. The flowback of the dead well after the fracturing (namely, flowback operation is carried out after the dead well is carried out for a period of time after the fracturing of the shale gas fracture network) is taken as a yield increasing technology for promoting the development of matrix microcracks, increasing the complexity of fracture networks and improving the initial yield of single wells, and is an important guarantee for promoting the economic and efficient development of deep shale gas. The long-term kill after fracturing provides sufficient time for imbibition-hydration between the reservoir rock and the fracturing fluid. Since the fracturing fluid is much cooler than the deep shale reservoir (which is typically normal temperature when the fracturing fluid is injected above ground), a large temperature gradient is created between the rock and the fluid contacting surface when the high temperature rock in the bottom layer is contacted with the relatively low temperature fracturing fluid. Such a temperature gradient can lead to non-uniformity of thermal stresses generated between reservoir rocks, affecting the rock micro-pore structure and thus the rock permeability. The prior equipment and the related experimental method aim at testing the permeability and the microscopic pore structure of the rock core under the constant temperature condition, and the prior equipment and the related experimental method have the advantage that the microscopic pore structure of the permeability of the rock core caused by the temperature gradient in the fracturing process is considered. The research requirements of people on the development process of oil and gas fields cannot be met, and a novel displacement experiment physical model is needed, so that the requirements of people on microscopic experiment research are further met on the basis of the conventional physical model. Disclosure of Invention The invention aims to provide a core holder for a thermal stress fracture experiment and an experiment method, aiming at solving the technical problems in the background technology. In order to achieve the above purpose, the present invention adopts the following technical scheme: a core holder for thermal stress fracturing experiments, comprising: The heat preservation pipeline sleeve comprises a through cavity, a heating device is arranged at one end of the heat preservation pipeline sleeve, a heat preservation layer is arranged in an area, except for the heating device, of the heat preservation pipeline sleeve, a first temperature sensor is arranged on the upper side of the area, opposite to the heat preservation layer, a transparent glass fiber reinforced plastic container is arranged on the lower side of the area, opposite to the heat preservation layer, a second temperature sensor is arranged on the heating device, a clamping device is used for clamping the heat preservation pipeline sleeve, a piston sleeve is arranged on the clamping device and used for introducing gas or liquid into the cavity of the heat preservation pipeline sleeve, and an experimental rock core is used for clamping the experimental rock core placed in the cavity of the heat preservation pipeline sleeve. In some embodiments, the heat-insulating pipeline kit comprises two concentric pipelines sleeved with each other, a heat-insulating layer is filled between the two concentric pipelines, and a reinforced heat-conducting copper pipe is filled between the two concentric pipelines, wherein the right end of the heat-insulating pipeline is wrapped by the heating device. In some embodiments, a plurality of mounting holes are drilled above and below the two concentric pipes, the first temperature sensor is located in the mounting hole above the concentric pipe, and the transparent glass reinforced plastic container is located in the mounting hole below the concentric pipe. In some embodiments, the heating device is an elliptical concentric copper tube with an interlayer, a heating resistor is wound in the interlayer, the second temperature sensor is arra