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CN-122016606-A - Core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback

CN122016606ACN 122016606 ACN122016606 ACN 122016606ACN-122016606-A

Abstract

The invention relates to a core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback. The system comprises a multi-medium precise injection system, a gradient temperature control core clamping system, an outlet multidimensional information sensing system, a dynamic coupling central control system and a pressure compensation and circulation reflux system. The central control system receives the feedback signal of the outlet end and adjusts the injection power and the axial gradient temperature control area in real time, so that the depth dynamic coupling of the seepage field, the temperature field and the stress field is realized. The invention solves the problems of constant injection temperature and lack of outlet feedback in the traditional experiment, can accurately reconstruct the real stratum temperature scale distribution, remarkably improves the physical fidelity and data reliability of the heat exchange coupling experiment, and provides an advanced experiment support platform for basic mechanism research in the field of energy development.

Inventors

  • LIU XIAOCHEN
  • Leng Jigao

Assignees

  • 运城职业技术大学
  • 北京宝石花能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260325

Claims (8)

  1. 1. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback comprises a multi-medium precise injection system, a gradient temperature control core clamping system, an outlet multidimensional information sensing system, a dynamic coupling central control system and a pressure compensation and circulation reflux system; the multi-medium precision injection system is characterized by comprising a high-pressure constant-flow constant-pressure pump set, a fluid preheating bin, a gas pressurizing buffer unit and a multi-path switching valve group, wherein a stroke displacement monitoring sensor is arranged in the high-pressure constant-flow constant-pressure pump set, the fluid preheating bin is designed by adopting a double-cavity body and is internally provided with a spiral heat exchange pipeline, a1 st-stage platinum thermal resistance sensor is embedded into the inner wall of the fluid preheating bin, the gradient temperature control core clamping system comprises a high-strength stainless steel cylinder body, a fluororubber sealing sleeve, a sectional type electric heating sleeve, a hydraulic pressurizing station and an axial displacement monitoring unit, the sectional type electric heating sleeve is tightly attached to the outer surface of the high-strength stainless steel cylinder body and is divided into at least 5 independent heating areas at equal intervals along the axial direction, each heating area is independently provided with a proportional integral differential controller and a2 nd-stage platinum thermal resistance sensor, the axial displacement monitoring unit acquires the axial deformation of a core under the coupling effect of high temperature and high pressure through a laser displacement meter arranged at the pressurizing piston end, the outlet multi-dimensional information sensing system is arranged at an outlet pipeline of the core clamp, comprises a corrosion-resistant measuring cavity body, the measuring cavity is integrated with a thermocouple array in response time of 50 milliseconds, the back of the measuring cavity is sequentially connected with a high-frequency pressure transmitter and an ultrasonic flowmeter, the sampling frequency of the high-frequency pressure transmitter is not lower than 100Hz, a heat exchange coupling control logic which is evolved based on the energy conservation law and the Darcy law is arranged in the dynamic coupling central control system and is used for receiving a feedback signal of the outlet multidimensional information sensing system, extracting the deviation value of the outlet temperature and the inlet temperature in real time, and calculating the heat exchange efficiency in the core by combining the instantaneous flow rate captured by the ultrasonic flowmeter, and the pressure compensation and circulation reflux system comprises an automatic back pressure valve, a multistage heat exchange condenser and a gas-liquid separation collector.
  2. 2. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback is characterized in that the heat exchange coupling control logic comprises the following operation processes of carrying out integral operation on a core sectional area, carrying out coupling treatment on a temperature-related permeability function, a pressure gradient vector, fluid dynamic viscosity which is dynamically adjusted along with real-time temperature, fluid density, specific heat capacity and seepage speed which is captured by an ultrasonic flowmeter in real time to obtain energy migration total quantity which comprises a seepage mechanical energy conversion item and a heat convection item, calculating apparent heat exchange intensity by calculating heat enthalpy difference between an outlet and an inlet of the core and combining specific heat capacity, instantaneous flow and equivalent heat conductivity of a core skeleton of a fluid medium, comparing the apparent heat exchange intensity with a preset theoretical heat exchange model, extracting a thermal short circuit compensation coefficient or a retention effect compensation coefficient which is caused by seepage non-uniformity, and dynamically generating a power correction instruction of each heating area according to the thermal short circuit compensation coefficient or the retention effect compensation coefficient.
  3. 3. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback according to claim 1, wherein the segmented electric heating sleeve is of an external wrapping heat insulation layer structure, the heat insulation layer is made of nano aerogel felt with a heat conductivity coefficient lower than 0.02W/m Kelvin, an active heat dissipation cooling ring is arranged at intervals among all heating areas and used for preventing heat conduction coupling interference of adjacent heating areas, and the dynamic coupling central control system is further used for dynamically adjusting the magnitude of axial load through a hydraulic pressurizing station according to axial deformation data acquired by a laser displacement meter so as to offset additional stress generated by thermal expansion.
  4. 4. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback according to claim 1 is characterized in that the fluid preheating bin comprises a main cavity and an auxiliary cavity, the main cavity performs primary temperature rise, the auxiliary cavity performs temperature adjustment through a proportional integral derivative control algorithm, a stop valve is arranged between the main cavity and the auxiliary cavity, when injection fluid is converted from a liquid state to a gas state or a supercritical state, the dynamic coupling central control system changes the heat exchange length through which the fluid flows through a multi-way switching valve group, and the multi-medium precision injection system is further provided with a vacuum extraction unit for vacuumizing a pipeline and a core sample body before an experiment starts, so that the vacuum degree is below 10 Pa.
  5. 5. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback according to claim 1 is characterized in that the inner surface of the measurement cavity is treated by polytetrafluoroethylene coating, the thermocouple arrays are distributed at the center and the edge of the flow passage section of the measurement cavity and used for capturing temperature differences of fluid caused by seepage path differences, the high-frequency pressure transmitter is used for capturing pressure pulsation in the seepage process, and the ultrasonic flowmeter obtains instantaneous flow rates of the fluid at different temperatures in a non-contact measurement mode.
  6. 6. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback according to claim 2 is characterized in that a thermal balance correction algorithm is further built in the dynamic coupling central control system, the thermal balance correction algorithm comprises the following operation processes of obtaining total heat flow density input by a segmented electric heating sleeve to a core, length and cross-sectional area of the core, monitoring temperature of the wall surface of a high-strength stainless steel cylinder and average temperature of outlet fluid, calculating an equivalent heat conductivity coefficient under the core scale by combining the heat dispersion correction coefficient determined by seepage Reynolds number, and controlling temperature difference values among axial 5 heating areas by the dynamic coupling central control system based on the calculated equivalent heat conductivity coefficient.
  7. 7. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback is characterized in that the automatic back pressure valve is used for driving and adjusting the opening of a needle valve by a high-precision stepping motor by receiving pneumatic signals of a dynamic coupling central control system, the displacement control precision of the high-precision stepping motor reaches 0.5 micrometers, the pore pressure is adjusted to be 0.01 megapascal, the multistage heat exchange condenser adopts a countercurrent water cooling structure and is used for cooling fluid at an outlet end to a range of 20-30 ℃, and the gas-liquid separation collector is used for metering produced oil, water and gas in real time and collecting samples by utilizing the principle of gravity sedimentation and cyclone separation.
  8. 8. The core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback according to claim 1 is characterized in that the dynamic coupling central control system further has a data synchronous mapping function and is used for conducting time stamp alignment processing on data streams of a1 st-stage platinum thermal resistance sensor, a2 nd-stage platinum thermal resistance sensor, a thermocouple array, a high-frequency pressure transmitter and an ultrasonic flowmeter, the processed data are imported into a preset stratum equivalent heat flow model, apparent permeability, heat conductivity and heat dispersion coefficient of a core are calculated in real time, a sampling cycle period of the dynamic coupling central control system is set to be 10 milliseconds, and a safety pre-warning module is integrated in the dynamic coupling central control system and is used for triggering an emergency shutdown program and starting a cooling circulating pump when the temperature of a heating area is detected to be 10% beyond a set range or abnormal pressure fluctuation.

Description

Core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback Technical Field The invention belongs to the technical field of petroleum geological exploration and core experiment simulation, and particularly relates to a core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback. Background In the fields of energy development, geothermal exploitation and underground reservoir engineering, a core seepage experiment is a basic means for revealing the migration rule and evolution mechanism of multiphase fluid in a porous medium. Through high-precision experimental simulation, the complex physicochemical process of the underground reservoir can be restored, and key data support is provided for resource evaluation and exploitation scheme optimization. With the expansion of deep and ultra-deep resource development scale, the research on the migration behavior of fluid in an extreme temperature and pressure environment is more important, which requires that a simulation system has high physical fidelity to accurately capture the dynamic evolution characteristic of an underground complex flow field. The heat exchange dynamic coupling simulation in the core seepage process is a core technical link for evaluating thermal oil recovery, geothermal circulation and fluid injection induced thermal response. The direction focuses on heat transfer between the fluid flowing in the porous medium and the solid framework and the influence of the heat transfer on the seepage characteristic, and the regulation and control effect of thermodynamic parameter change on the fluid flowing behavior is studied by constructing a controlled temperature field environment. The accurate heat exchange coupling simulation has important academic value and engineering significance for understanding the energy conversion, pressure decay and phase evolution process. However, most of the existing core seepage experimental devices adopt an injection mode with fixed temperature, and based on the idealized assumption that the outside of the core is a constant-temperature boundary condition, the whole holder is generally and uniformly heated by using only an external heating sleeve or a constant-temperature water bath. Such systems ignore the natural temperature gradients that are widely present in actual formations and fail to reflect the effects of temperature rise or fall of the injected fluid and rock during the seepage process due to the continued heat exchange. Due to the lack of a real-time sensing and feedback mechanism for the outlet fluid state, the traditional equipment is difficult to reproduce the along-path dynamic evolution rule of the physical parameters such as fluid viscosity, density and the like along with the temperature change, so that experimental data often only reflect the average characteristics in a steady state. In addition, the existing monitoring means stay in an isolated data recording stage, and the monitoring signal does not establish closed-loop control logic with the front-end injection system, so that the active regulation and control of the unsteady state heat flow coupling process becomes a bottleneck. These defects together lead to significant deviation between the experimental process and the underground real physical process, and restrict the depth and the precision of the dynamic heat exchange mechanism research under the complex working condition. Disclosure of Invention The invention aims to provide a core seepage heat exchange dynamic coupling simulation system based on outlet temperature feedback, which is used for solving the problem that in the existing core seepage experiment, the deviation between an experimental result and an actual geological condition is large because the injection temperature is constant, outlet state feedback is lacked, and the actual stratum temperature gradient cannot be simulated. In order to achieve the above object, the present invention provides a technical solution, including: the multi-medium precise injection system is used for continuously supplying fluid medium with specific temperature and pressure to the end part of the rock core according to preset experimental working conditions; the gradient temperature control core clamping system is used for bearing a core sample body, applying radial confining pressure and axial load to the core sample body, and constructing a non-uniform simulated stratum temperature field through a plurality of independent temperature control intervals distributed along the axial direction of the core; The outlet multidimensional information sensing system is used for monitoring the temperature, pressure, instantaneous flow and component information of fluid flowing out from the outlet end of the core in real time, and converting monitoring data into electric signals for transmission; The dynamic coupling central control system is used as a logic core of the system and