CN-122016921-A - Rock sample crack heat exchange performance test system and method

CN122016921ACN 122016921 ACN122016921 ACN 122016921ACN-122016921-A

Abstract

The invention provides a rock sample crack heat exchange performance test system and a method, which relate to the technical field of experimental equipment and comprise a rock sample holder, an injection module, a confining pressure module, a back pressure module, a collection module, a heating module, a monitoring assembly and a data acquisition module, wherein the rock sample holder comprises an experimental chamber and a confining pressure chamber; the injection module is communicated with the experiment chamber, the confining pressure module is communicated with the confining pressure chamber, the back pressure module is used for controlling fluid pressure difference, the collecting module is used for collecting seepage test fluid, the monitoring assembly is used for monitoring at least one of injection flow, pressure, temperature, confining pressure and fluid seepage quality data, and the data collecting module is used for collecting and storing the injection flow, pressure, temperature, confining pressure and fluid seepage quality data in real time. According to the invention, through the cooperation of the multiple modules, the high-precision and full-flow monitoring of the heat transfer characteristic of the fractured rock sample under the conditions of complex stress and thermal field is realized, and the accuracy of the measurement of the convective heat transfer coefficient is improved.

Inventors

WANG JI
LI PUJIANG
WANG WEIDONG
WANG HAO
ZHANG YUNING

Assignees

中国石油大学(北京)

Dates

Publication Date: 20260512
Application Date: 20260119

Claims (10)

1. A rock sample fracture heat transfer performance testing system, comprising: a rock sample holder including an experiment chamber for holding a rock sample preset with a crack, and a confining pressure chamber provided outside the experiment chamber; The injection module is communicated with the inlet of the experimental chamber and is used for driving fluid to enter a rock sample with preset cracks; the confining pressure module is communicated with the confining pressure cavity and is used for applying confining pressure to a rock sample with a preset crack; the back pressure module is communicated with the outlet of the experimental chamber and is used for controlling the fluid pressure difference in a matched mode with the injection module; the collection module is communicated with the outlet of the experiment chamber and is used for collecting the seeped test fluid; the heating module is arranged on the rock sample holder and is used for heating a rock sample with a preset crack; the monitoring component is used for monitoring at least one of injection flow, pressure, temperature, confining pressure and fluid seepage quality data; The data acquisition module is electrically connected with the monitoring component and is used for acquiring and storing the injection flow, pressure, temperature, confining pressure and fluid seepage quality data in real time.
2. The rock sample fracture heat exchange performance test system according to claim 1, wherein the injection module comprises an injection pipeline for communicating with an inlet of the experimental chamber and a fluid supply pipeline, the injection pipeline is sequentially provided with an injection pump, a piston type intermediate container and an injection control valve, the fluid supply pipeline is communicated with a liquid inlet of the piston type intermediate container, and the fluid supply pipeline is sequentially provided with a constant temperature water tank, an injection flowmeter and a medium control valve.
3. The rock sample fracture heat exchange performance test system of claim 2, wherein the confining pressure module comprises a confining pressure pipeline, a confining pressure supply tank, a confining pressure control valve, a confining pressure pump and a communicating vessel disposed on the confining pressure pipeline, the communicating vessel being configured to communicate with the confining pressure chamber.
4. The rock sample fracture heat exchange performance test system according to claim 3, wherein the back pressure module comprises a back pressure pipeline used for being communicated with an outlet of the experimental chamber and a back pressure supply pipeline, a hand pump and an outlet back pressure valve are sequentially arranged on the back pressure pipeline, the back pressure supply pipeline is communicated with the back pressure pipeline, and a back pressure tank and a back pressure regulating control valve are sequentially arranged on the back pressure supply pipeline.
5. The rock sample fracture heat exchange performance test system of claim 4, wherein the collection module comprises an outflow line, and a collection vessel, the monitoring assembly comprising a flow measurement scale, the collection vessel being disposed on the flow measurement scale, the outflow line communicating an outlet of the laboratory chamber with the collection vessel.
6. The rock sample fracture heat exchange performance test system of claim 1, wherein the heating module comprises a heating assembly sleeved on the rock sample holder, and a heating console electrically connected to the heating assembly.
7. The rock sample fracture heat exchange performance test system of claim 5, wherein the rock sample holder comprises: a holder housing; the two ends of the sealing rubber sleeve are respectively provided with a step structure, the sealing rubber sleeve is arranged in the clamp holder shell, the inner cavity of the sealing rubber sleeve forms the experiment chamber, and the interval area between the sealing rubber sleeve and the clamp holder shell forms the confining pressure chamber; The two sealing assemblies are respectively arranged at two ends of the clamp holder shell, each sealing assembly comprises an external thread sleeve connected with the clamp holder shell in a threaded mode, an internal thread sleeve connected with the external thread sleeve in a threaded mode in a spliced mode, a cylindrical smooth sealing device coaxially arranged with the internal thread sleeve, a stepped smooth sealing device sleeved on the outer side of the cylindrical smooth sealing device and abutted with the external thread sleeve, and a sealing ring arranged on the outer wall of the stepped smooth sealing device, the sealing ring can be abutted to the outer wall of the clamp holder shell in a sealing mode, the stepped smooth sealing device can be matched with the step structure of the sealing rubber sleeve in a matched mode, and a pipeline channel extending along an axis is arranged on the cylindrical smooth sealing device.
8. The rock sample fracture heat exchange performance test system according to claim 7, wherein one of the cylindrical smooth sealing devices is further provided with an open-pore channel, the open-pore channel is communicated with the experimental chamber and the inner cavity of the internally threaded sleeve, and the open-pore channel is used for allowing a lead of a temperature sensor to pass through.
9. The rock sample fracture heat exchange performance test system of claim 8, wherein the monitoring assembly comprises an inlet temperature sensor, an inlet pressure sensor, a back pressure sensor, an outlet temperature sensor, an outlet pressure sensor, a confining pressure sensor, and at least one rock sample temperature sensor for placement on an outer surface of a rock sample and/or embedded in a fracture of a rock sample; The inlet pressure sensor is arranged on the injection pipeline, the back pressure sensor and the outlet pressure sensor are arranged on the outflow pipeline, and the confining pressure sensor is arranged on the confining pressure pipeline; An injection tee joint component is arranged on the injection pipeline, and the inlet pressure sensor and the inlet temperature sensor can be directly contacted with the inlet end face of the rock sample through the injection tee joint component and are electrically connected with the data acquisition module; the outlet tee joint component is arranged on the outflow pipeline, the outlet pressure sensor and the outlet temperature sensor can be in direct contact with the outlet end face of the rock sample through the outflow tee joint component and are electrically connected with the data acquisition module, and the rock sample temperature sensor can be electrically connected with the data acquisition module through the perforated channel.
10. A method for testing heat exchange performance of a rock sample fracture, which is realized by using the rock sample fracture heat exchange performance testing system according to any one of claims 1 to 9, and comprises the following steps: preparing a rock sample with preset cracks; Testing the rock sample by using a rock sample crack heat exchange performance testing system to obtain experimental data; based on the experimental data, calculating the heat exchange performance, wherein the calculating method comprises the following steps: And determining the flowing state of the fluid in the rock sample fracture by adopting a Reynolds number Re, wherein the Reynolds number Re has a calculation formula as follows: Wherein d is the diameter of the rock sample, the unit m is v is the motion viscosity coefficient of water, the unit m 2 /s;q v is the volume flow rate of water, and m 3 /s; Calculating distribution T r (x) of the temperature of the outer surface of the rock sample along the axis, and fitting by adopting temperature measuring point data of the outer surface of the rock sample, wherein the temperature measuring point data of the outer surface of the rock sample at least comprises T r1 、T r2 、T r3 , and the calculation formula of T r (x) is as follows: wherein l is the arrangement interval, m, x is the length from the end face of the inlet, m, T is the temperature, K; Calculating distribution T s (x) of the surface temperature of the rock sample fracture along the axis, and fitting by adopting rock sample fracture surface temperature measuring point data, wherein the adopted rock sample fracture surface temperature measuring point data at least comprises T s1 、T s2 、T s3 , and the calculation formula of T s (x) is as follows: wherein l is the arrangement interval, m, x is the length from the end face of the inlet, m, T is the temperature, K; Calculating a convection heat transfer coefficient h and evaluating the heat transfer effect of fluid and the surface of the rock sample fracture, wherein the calculation formula of the convection heat transfer coefficient h is as follows: Wherein, subscript 1 expresses the inlet parameter of the rock sample, subscript 2 expresses the outlet parameter of the rock sample, wherein u 1 、u 2 is the flow velocity of the fluid, m/s, ρ 1 、ρ 2 is the density of the fluid, kg/m 3 ;A 1 、A 2 is the flow sectional area in a single crack, m 2 ;c p is the specific heat capacity at constant pressure, J/(kg.K), T 1 、T 2 is the fluid temperature, K, A s is the effective heat transfer area of the single crack, m 2 ;T s is the temperature of the surface of the rock sample crack, K, T f is the temperature of the fluid, K.

Description

Rock sample crack heat exchange performance test system and method Technical Field The invention relates to the technical field of experimental equipment, in particular to a rock sample crack heat exchange performance test system and method. Background The dry hot rock is used as clean geothermal resource with huge reserves, and large-scale exploitation of the dry hot rock has important significance for pushing the energy structure to transform. The enhanced geothermal system (Enhanced Geothermal System, EGS) is used as the most effective core technology for developing dry hot rock at present, can efficiently and economically convert heat energy in deep high Wen Yanti into electric energy, effectively meets the requirement of large-scale sustainable energy, and becomes the main technical direction for the development and utilization of geothermal energy. The core of the EGS system is to realize the efficient extraction of geothermal heat through an artificial fracture network, and the EGS system is usually located in volcanic magma activity frequent areas such as plate extrusion belts, and the EGS system has abundant geothermal heat resources and good natural fracture foundation. By arranging injection wells and extraction wells and implementing reservoir stimulation means such as hydraulic fracturing, a stable and penetrating artificial crack network is constructed in the low-permeability dry-hot rock. The low-temperature fluid flows through the high Wen Liexi under the drive of pressure through the injection well, and forms high-temperature fluid after heat exchange with the rock wall, and the high-temperature fluid is output by the extraction well and used for generating electricity. The heat exchange efficiency between the fluid and the fractured rock mass directly determines the productivity level and the operation economy of the system, which are key indexes for the development of the EGS technology. However, the existing indoor single-crack flow heat exchange experiment still faces a plurality of technical bottlenecks, namely, the fluid injection temperature is difficult to control accurately, initial conditions are inconsistent under different working conditions, the temperature sensor is arranged far away from the rock sample body, so that the injection temperature and the outflow temperature are larger in measurement error, the heating temperature is generally used for replacing the rock surface temperature approximately, the additional thermal resistance brought by the rubber sleeve and the shell is ignored, the data accuracy is influenced, and the real temperature of the crack surface inside the rock sample cannot be measured directly, and is estimated by relying on theoretical derivation or numerical simulation, so that the calculation of the convective heat exchange coefficient has obvious deviation. Because single slit is a basic constitution unit of the complex slit net, the accurate representation of the heat transfer characteristic is a precondition for breaking through the bottleneck of EGS heat exchange efficiency. Therefore, how to accurately obtain the convective heat transfer coefficient of the rock sample fracture becomes a technical problem to be solved at present. Disclosure of Invention In order to overcome the defects in the prior art, the embodiment of the invention provides a rock sample crack heat exchange performance test system and a method, which are used for accurately acquiring the convective heat exchange coefficient of a rock sample crack. The above object of the invention can be achieved by adopting the following technical scheme, and the invention provides a rock sample crack heat exchange performance test system, which comprises: a rock sample holder including an experiment chamber for holding a rock sample preset with a crack, and a confining pressure chamber provided outside the experiment chamber; The injection module is communicated with the inlet of the experimental chamber and is used for driving fluid to enter a rock sample with preset cracks; the confining pressure module is communicated with the confining pressure cavity and is used for applying confining pressure to a rock sample with a preset crack; the back pressure module is communicated with the outlet of the experimental chamber and is used for controlling the fluid pressure difference in a matched mode with the injection module; the collection module is communicated with the outlet of the experiment chamber and is used for collecting the seeped test fluid; the heating module is arranged on the rock sample holder and is used for heating a rock sample with a preset crack; the monitoring component is used for monitoring at least one of injection flow, pressure, temperature, confining pressure and fluid seepage quality data; The data acquisition module is electrically connected with the monitoring component and is used for acquiring and storing the injection flow, pressure, temperature, confining pressure