Search

CN-121993370-A - Underground integrated low-temperature geothermal ORC power generation system suitable for abandoned oil well

CN121993370ACN 121993370 ACN121993370 ACN 121993370ACN-121993370-A

Abstract

The invention discloses a technical scheme of an underground integrated low-temperature geothermal ORC power generation system suitable for abandoned oil wells, which belongs to the field of power generation and energy utilization and is characterized in that an underground sealed pressure-bearing power generation main body, a totally-enclosed organic working medium circulation system, a deep geological exploration module and a ground control unit are integrated underground in a modularized manner, so that heat source direct heat transfer, thermal-electric closed loop and zero stratum water contact are realized. The evaporator is directly attached to the underground outer wall to realize heat exchange, the working medium heats up and evaporates and drives the generator to output power through the expander, the vortex tube is connected in series to condensate and return liquid through inert media, the geological data at the bottom of the well can be stored offline and transmitted to the ground in real time, the righting positioning mechanism is self-adaptive to the inner diameter of a shaft of 3-7 inches, the armored cable realizes the bidirectional transmission and remote control between the underground and the ground, the advantages of low environmental risk, modularization, low cost investment and the like are achieved, and the device is suitable for improving geothermal potential and regional exploration of waste oil wells.

Inventors

  • ZHOU ZIJUN

Assignees

  • 周子俊

Dates

Publication Date
20260508
Application Date
20260407

Claims (10)

  1. 1. S1, directly exchanging heat between an evaporator assembly and a well wall underground, transferring geothermal heat to a working medium, and heating and evaporating the working medium in the evaporator assembly to form a high-pressure gas-phase working medium; the method comprises the steps of collecting underground heat source temperature, evaporator outer wall temperature, working medium initial state and sealing state data, carrying out closed-loop monitoring on heat exchange efficiency, pressure-temperature state and sealing state in the evaporation process, adopting a self-adaptive heat exchange control strategy to ensure that the working medium enters a high energy state under the condition of no leakage, outputting a high-pressure gas phase working medium to an expander, S2, sending the high-pressure gas phase working medium to the expander, pushing the expander to do work and driving a generator to output power, outputting the power to be scheduled by a ground control unit, collecting the high-pressure gas phase working medium state, an expansion ratio set value and current load data of the generator in the process, dynamically regulating and controlling in an expansion ratio adjustable range, matching geothermal temperature conditions and guaranteeing safe operation, S3, adopting a condenser with a vortex tube series structure, carrying out heat exchange through inert gas media to realize working medium condensation, and maintaining working medium closed-loop circulation, collecting condenser temperature, inert medium state and circulating pump flow data, carrying out real-time control on condensation efficiency, heat exchange strength and circulating pump working state, outputting liquid working medium to the evaporator inlet and outputting stable power, S4, carrying out temporary underground formation filtering, exploring temperature and stratum management, carrying out online stratum management on the data acquisition and offline formation management, the method comprises the steps of (1) transmitting stratum data to a ground control unit, S5, realizing bidirectional transmission of data and power output of an underground system through an armored cable, issuing remote control instructions, completing closed loop control and state feedback of the underground system, S6, collecting shaft inner diameter information and current state data of a positioning mechanism through a centralizing positioning mechanism, realizing self-adaptive fixing and anti-collision positioning of the inner diameter of a shaft of 3 to 7 inches, completing stable fixing of an underground power generation unit, S7, collecting sealing states and leakage detection signals in real time by a system, continuously evaluating the sealing integrity of a fully-closed organic working medium circulation system, triggering an alarm and outputting an emergency processing instruction in abnormal conditions, S8, finishing, compressing and offline storing off-line operation log and regional resource data by the system, uploading the off-line operation log and the regional resource data to the ground control unit as required, generating off-line data files and supporting data playback, and S9, realizing high-efficient and safe operation of the system and continuous output of power and thermal-electric coupling data by combining the heat source state, working medium circulation state and the ground control instructions.
  2. 2. The operation method according to claim 1, wherein in step S1, the state data of the working medium at the evaporation inlet is also collected synchronously, and the heat exchange intensity at the evaporation stage is optimized by dynamically evaluating the expansion ratio, the temperature gradient of the working medium and the thermal resistance change, and the working medium in the evaporator assembly is ensured to stably enter a controllable high energy state in combination with a sliding window detection mechanism.
  3. 3. The operation method according to claim 1, wherein in the step S2, output power trend of the expander, efficiency evaluation of the generator, and working medium state curve data are synchronously collected, expansion ratio is dynamically adjusted by a closed-loop control algorithm, and different geothermal temperature conditions are matched, so that smooth power output is realized.
  4. 4. The operation method according to claim 1, wherein in the steps S4 and S5, the ground control unit performs intelligent scheduling according to the collected stratum geological data and the system operation state, translates the ground control instruction into a specific action of the downhole equipment and monitors the execution process, and meanwhile, according to the transmission network state, adopts a mixed mode management of offline caching and online transmission to stratum data to complete data filtering and time sequence alignment processing, and performs error detection and redundant transmission to the issued remote control instruction to ensure safe arrival and reliable execution of the instruction.
  5. 5. The underground integrated low-temperature geothermal ORC power generation device is characterized by comprising an underground integrated power generation unit, a totally-enclosed organic working medium circulation system, a deep geological exploration module, a ground control unit and a centralizing and positioning mechanism, wherein the totally-enclosed organic working medium circulation system is arranged in a sealed pressure-bearing cavity of the underground integrated power generation unit, a closed loop path sequentially comprises an evaporator assembly, an expander, a generator, a condenser, a circulating pump and a connecting pipeline, the evaporator assembly is of a heat exchange structure directly attached to the outer wall of the underground power generation unit and used for realizing working medium evaporation through direct heat exchange with a well wall, the expander and the generator are of a single-shaft coupling structure, an expansion ratio is provided with an adjustable section and used for driving the generator to output power through working medium expansion work, the condenser is of a vortex tube series heat exchange structure and is used for taking inert gas as a heat exchange medium and used for realizing working medium condensation, the deep geological control unit is integrated with a temperature sensor, a pressure sensor and a lithology detection assembly and used for acquiring stratum data and supporting real-time transmission or off-line storage, the ground control unit is connected with the underground power generation unit through a cable and used for realizing the direct heat exchange, and the underground power transmission and the underground integrated power generation unit is provided with the underground integrated power generation unit and the two-direction buffer tube, and the underground integrated power generation unit is provided with a flexible sleeve tube and a flexible sleeve tube, and a self-adaptive positioning mechanism is used for realizing the underground well.
  6. 6. The power generation device of claim 5, wherein the evaporator assembly is controlled by contact thermal resistance to realize efficient heat transfer, and the thermal contact area and the flow of the working medium can be regulated and controlled according to the temperature of the outer wall of the well, the temperature of the inlet of the working medium and the heat conduction coefficient data to realize stable evaporation of the working medium.
  7. 7. The power generation device according to claim 5, wherein the expander and the generator set can adjust the expansion ratio through closed loop control according to the output power of the expander, the load of the generator and the state data of working medium, so as to achieve power output smoothing and stable power output.
  8. 8. The power generation device according to claim 5, wherein the condenser can adaptively regulate and control condensation efficiency according to inert medium temperature, flow rate and pipeline resistance data, so that dependence on a surface condensation system is reduced, and stable backflow of liquid working medium to an inlet of the evaporator is ensured.
  9. 9. A computer readable storage medium, wherein the computer readable storage medium stores a computer program, and when the computer program is executed by a processor, the computer program realizes the operation method of the underground integrated low-temperature geothermal ORC power generation system according to any one of claims 1 to 4, and the computer program comprises a subroutine for parameter regulation and control of an evaporator and an expander, optimization of heat exchange, and adjustment of working medium flow, a subroutine for offline storage and regional resource evaluation analysis of deep geological exploration data, a subroutine for data return and remote diagnosis of a ground control unit, a subroutine for system persistence self-check and safety strategy execution, a subroutine for working medium state history data analysis and parameter prediction, a time sequence control subroutine for equipment collaborative operation, a geological information fusion subroutine for regional geothermal potential analysis, and a subroutine for multi-scene operation simulation.
  10. 10. The computer readable storage medium of claim 9, wherein the subroutine for running simulation in multiple scenarios runs simulation and optimizes system parameters according to input geothermal conditions, wellbore conditions, and resource limitation data, and outputs an optimal running scheme adapted to the corresponding scenario.

Description

Underground integrated low-temperature geothermal ORC power generation system suitable for abandoned oil well Technical Field The invention relates to the field of power generation, in particular to an underground integrated ORC power generation system for directly converting low-temperature geothermal resources into electric power in the underground of a waste oil well and an integrated operation scheme thereof. Specifically, for the medium and low temperature geothermal source and the complex shaft environment, a compact coupling structure of a totally-enclosed working medium circulation and underground integrated power generation unit is provided, heat exchange is directly realized by directly attaching an evaporator to the underground outer wall, self-contained condensation of energy consumption on the ground surface is realized by utilizing vortex tube serial condensation, a deep geological exploration module and a ground control unit are integrated at the bottom of the well, and bidirectional data and power transmission and remote control between the underground and the ground are realized by means of an armored cable. The method aims at modularization, standardization and low cost investment, and is suitable for a modern development scheme for high-efficiency reuse of waste oil well resources and regional geothermal potential evaluation. Background The existing geothermal-power generation technology is mainly concentrated on the surface or the periphery of a shaft to extract heat energy and convert power generation, but various bottlenecks still exist under the conditions of abandoned oil wells and medium-low temperature geothermal, so that the resource utilization efficiency is low, the environmental risk is high, and the system cost is high. According to the disclosed technical analysis, the prior art can be broadly divided into the following schemes and their shortcomings: 1) Wellhead-surface power generation system based on ground heat exchange and water-ground heat coupling The geothermal heat source is coupled with the ground heat exchanger, heat is extracted at a wellhead or underground, then transferred to the evaporation/expansion device through a ground heat network, and then a power generation and condensation loop is completed at the ground surface. The underground water recycling system has the defects that a large-scale underground water recycling system and an earth surface condensing system are needed, the coupling risk of earth surface and underground water resources is easy to generate, multiple leakage and pollution hidden dangers exist in heat sources and earth surface environments, the fault tolerance to the difference of a shaft structure and an inner diameter is poor, and the integration of modularized standardized equipment in the shaft is difficult to realize. 2) Underground open-loop geothermal power generation system The working principle and the key point are that an open working medium circulation is formed underground, the working medium directly contacts with geothermal water/stratum fluid to complete the stages of evaporation, expansion, power generation, condensation and the like, and condensate is recycled. The method has the defects that the open circulation is easy to cause stratum water pollution, permeability damage and heat-water resource coupling risk, corrosion and leakage risk exist in long-term operation, the environmental supervision cost is high, and the compatibility and self-adaption of the inner diameter of a shaft are difficult to realize. 3) Multiple module integration scheme for downhole closed loop systems (but often only works at a single wellhead or within a specific borehole diameter) The working principle and the key point are that a closed system for circulating working medium is realized underground, and an evaporator, an expander, a generator, a condenser and other modules are integrated in a compact coupling mode. The method has the defects that the existing scheme is often insufficient in self-adaptive capacity for the inner diameter difference of the shaft, the self-adaptive fixation of the shaft with 3-7 inches is difficult to realize, the underground environment is complex, the requirements on equipment service life and reliability by the factors such as vibration, temperature, dust and the like are high, the standardization degree is low, the field installation cost is high, and the construction period is long. 4) Comprehensive application of underground geological data acquisition and remote control The method is characterized in that a geological sensing and data acquisition module is deployed at the bottom of a well, and data are transmitted to a ground control system through a communication link, so that field diagnosis and regional resource analysis are realized. The system has the defects that the existing system mainly uses independent data acquisition, lacks tight coupling with a thermo-electric closed loop system, cannot realiz