A deep and medium-depth composite geothermal exploitation system

Abstract

This invention discloses a deep and mid-deep geothermal extraction system. This system employs a coupling method between deep and mid-deep geothermal resources to improve geothermal extraction efficiency and introduces a novel carbon dioxide collection well to maximize the absorption of carbon dioxide from the geothermal layer. The system mainly consists of three parts: a deep carbon dioxide extraction system, a mid-deep water extraction system, and a heat conversion system. The deep carbon dioxide extraction system uses a high-pressure pump to transport carbon dioxide to the geothermal rock to absorb heat, and then collects the heat-rich carbon dioxide through multi-branch horizontal wells and transports it to the heat conversion system. The mid-deep water extraction system uses a water pump and U-shaped pipe to flow water through the geothermal layer to absorb heat, and then transports the hot water to the heat conversion system. The heat conversion system is responsible for converting this heat into electrical energy. This scheme not only improves geothermal extraction efficiency but also sequesters a portion of the carbon dioxide, promoting the development and utilization of geothermal energy.

Description

Technical Field

[0001] This invention belongs to the field of geothermal resource extraction, and particularly relates to a deep and medium-deep composite geothermal extraction system. Background Technology

[0002] Geothermal energy is a renewable energy source with enormous development potential as an environmentally friendly and sustainable energy type. Currently, there are two main methods for geothermal energy extraction. For medium-deep geothermal resources, underground aquifers are selected, and groundwater is directly extracted or heat is collected using U-shaped wells to heat the medium inside pipes. This method is only suitable for shallow geothermal resources, and the temperature of these resources is usually low, resulting in low efficiency in extraction and use. For deep geothermal resources, water pressure is typically used to break up large dry hot rock areas, creating or expanding cracks, and injecting large amounts of water. The water vapor is then collected using collection wells and transported to the surface for use. This extraction method requires a large amount of water resources, and only a small portion of the injected water can be collected after vaporization. Furthermore, because the underground rock strata are under high temperature and high pressure, the cracks created by a single water pressure cannot be used for a long time. Repeated fracturing of underground rock strata may generate unstable factors such as earthquakes, impacting the surrounding environment.

[0003] Against this backdrop, carbon dioxide geothermal extraction technology has gradually attracted attention. This technology utilizes the high density and low viscosity of supercritical carbon dioxide, as well as its good fluidity under high temperature and pressure, making carbon dioxide an ideal geothermal extraction medium. Using carbon dioxide as a heat transfer medium can save water resources and simultaneously sequester some carbon dioxide, reducing the greenhouse effect. However, existing technologies for geothermal extraction using carbon dioxide often face the problem of low carbon dioxide collection efficiency, leading to insufficient geothermal resource extraction. The fracture network generated by water injection and compression has a large and irregular radiation area, and due to the high temperature and high pressure environment deep underground, the recovery of carbon dioxide after heat exchange is difficult. This results in low carbon dioxide collection efficiency, thus affecting the overall efficiency of geothermal extraction.

[0004] Therefore, current geothermal extraction technologies mainly suffer from the following problems: insufficient temperature in medium and deep geothermal layers, making it difficult to reach the temperature required for thermal energy conversion using non-water extraction methods; high difficulty in deep geothermal extraction; low collection efficiency; and significant heat loss during transport to the surface. Summary of the Invention

[0005] The present invention aims to overcome the defects of the prior art and provide a deep and medium-deep geothermal composite extraction system. It uses a deep geothermal and medium-deep geothermal coupling method to increase geothermal extraction efficiency and provides a new carbon dioxide collection well to maximize the collection of carbon dioxide that has absorbed heat in the geothermal layer. At the same time, the medium-deep geothermal collection pipeline provides insulation for the carbon dioxide collected from the deep geothermal layer, further reducing heat loss.

[0006] To address the above problems, the present invention provides the following technical solution:

[0007] A deep and medium-deep geothermal extraction system includes a deep carbon dioxide extraction system, a medium-deep water extraction system, and a heat conversion system.

[0008] The deep carbon dioxide thermal recovery system includes a carbon dioxide compressor, a first high-pressure pump, a first gas pipeline, a horizontal well, a second high-pressure pump, a second gas pipeline, multi-branch horizontal wells, and monitoring equipment. The horizontal wells are connected to the carbon dioxide compressor via the first gas pipeline. The high-pressure pump injects compressed supercritical carbon dioxide into the fractures of the deep geothermal rock. The multi-branch horizontal wells are located above the main horizontal well. The second high-pressure pump provides negative pressure to the multi-branch horizontal wells to collect carbon dioxide that has fully absorbed geothermal energy, which is then transported to the heat conversion system via the second gas pipeline. Furthermore, the horizontal well walls are uniformly perforated. Water is first injected into the deep geothermal rock through these perforations by the high-pressure pump to create or expand fractures. Then, supercritical carbon dioxide is injected into the geothermal rock fractures through these perforations to absorb heat. The multi-branch horizontal wells consist of a main pipe and branch pipes. Small holes are uniformly arranged on the branch pipes for carbon dioxide extraction. The monitoring equipment includes temperature sensors, pressure sensors, seismic detection equipment, and flow meters for real-time monitoring of underground conditions. To minimize heat loss, the second gas pipeline is installed at a depth of medium to deep within a vertical pipe aligned with the water outlet direction of the U-shaped well. This design makes the system more efficient and improves the utilization rate of geothermal energy.

[0009] The medium-deep geothermal extraction system consists of a water pump and a U-shaped pipeline. The horizontal section of the U-shaped pipeline is located in the medium-deep aquifer, and both ends are connected to the ground by vertical pipelines. The water pump drives water through the pipeline to absorb heat from the medium-deep geothermal layer and outputs it to the heat conversion system.

[0010] The heat conversion system consists of a heat exchanger and a power generation system. The carbon dioxide and water output from the heat harvesting system transfer heat to the heat transfer medium through the heat exchanger, and are then converted into electrical energy through the power generation system.

[0011] Through the above design, the present invention not only increases the output temperature of geothermal energy, but also realizes the full exploitation of deep and medium-deep geothermal resources, improves the utilization efficiency of geothermal energy, and further promotes the development and utilization of geothermal energy. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the system structure. Detailed Implementation

[0013] The following examples illustrate specific implementations of the present invention. However, these examples are merely for illustrative purposes and do not limit the scope of the invention in any way.

[0014] As shown in the figure, the present invention provides a deep and medium-deep composite geothermal extraction system, including a deep carbon dioxide thermal extraction system, a medium-deep water thermal extraction system, and a heat conversion system.

[0015] In a deep carbon dioxide heating system, water is first injected into the deep geothermal rock through holes in the wall of a horizontal well by a first high-pressure pump. Under the pressure of the water, large blocks of dry hot rock are cracked, creating a network of fractures for carbon dioxide to pass through. Then, a carbon dioxide compressor is used to compress the carbon dioxide to a supercritical state, and then the high-pressure pump is used to pump it into the network of fractures in the deep dry hot rock through a first gas pipeline and a horizontal well.

[0016] The multi-branch horizontal well is located above the horizontal well and consists of a main pipe and several branch pipes. Based on the detection of the dry hot rock fracture network generated by water injection, the length and position of the main pipe are selected so that the branch pipes on the main pipe can pass through as many densely fractured parts of the fracture network as possible. Small holes are evenly distributed on the branch pipes. By using a second high-pressure pump to provide negative pressure to the multi-branch horizontal well, carbon dioxide in the fracture network is collected and transported to the heat conversion system via a second gas transmission pipeline.

[0017] The medium-deep geothermal system operates synchronously with the deep carbon dioxide geothermal system. The system consists of a water pump and a U-shaped pipe. Water is injected into the U-shaped pipe, and the water flow rate is controlled so that the water absorbs heat as it flows through the medium-deep geothermal layer, and is then pumped out to the heat conversion system.

[0018] Subsequently, the heat conversion system, consisting of a heat exchanger and a power generation system, begins operation. The carbon dioxide and water output from the heat extraction system transfer heat to the heat transfer medium via the heat exchanger, and then the power generation system converts the heat into electrical energy.

[0019] In this way, the entire geothermal extraction system can achieve effective and efficient geothermal energy collection and utilization, highlighting the improvement of geothermal resources and carbon dioxide collection efficiency, while also making the development and utilization of geothermal resources more comprehensive and in-depth.

Claims

1. A deep and medium-deep composite geothermal extraction system, characterized in that, include: Deep carbon dioxide thermal extraction system, medium-deep water thermal extraction system, heat conversion system; The deep carbon dioxide thermal energy harvesting system comprises a carbon dioxide compressor, a first high-pressure pump, a first gas transmission pipeline, a horizontal well, a second high-pressure pump, a second gas transmission pipeline, a multi-branch horizontal well, and detection equipment. The horizontal well is connected to the carbon dioxide compressor through the first gas transmission pipeline. The first high-pressure pump inputs compressed supercritical carbon dioxide into the fractures of the deep geothermal rock. The multi-branch horizontal well is located above the horizontal well. The second high-pressure pump provides negative pressure to the multi-branch horizontal well to collect carbon dioxide that has fully absorbed geothermal energy and transports it to the heat conversion system through the second gas transmission pipeline. The medium-deep geothermal system includes a water pump and a U-shaped pipe. The horizontal part of the U-shaped pipe is located in the medium-deep aquifer, and both ends are connected to the ground by vertical pipes. The water pump drives water through the pipe to absorb heat from the medium-deep geothermal layer and outputs it to the heat conversion system. The second gas transmission pipeline is installed at a depth of medium to deep within a vertical pipe in the direction of the water outlet of the U-shaped well to reduce heat loss; The heat conversion system consists of a heat converter and a power generation system. The carbon dioxide and water output by the heat collection system transfer heat to the heat medium through the heat converter, and are then converted into electrical energy through the power generation system.

2. The deep and intermediate-deep composite geothermal extraction system according to claim 1, characterized in that, The horizontal well wall is uniformly arranged with holes. Before heat extraction, water is injected into the deep geothermal rock through the holes in the horizontal well wall by a high-pressure pump to create or expand the cracks. Then, supercritical carbon dioxide is injected into the geothermal rock cracks through the holes to absorb heat.

3. The deep and intermediate-deep composite geothermal extraction system according to claim 1, characterized in that, The multi-branch horizontal well consists of a main pipe and branch pipes. The length of the main pipe matches the length of the horizontal well. The branch pipes are evenly arranged on the main pipe and extend radially into the formation. Small holes are evenly arranged on the branch pipes for absorbing carbon dioxide.

4. A deep and intermediate-deep composite geothermal extraction system according to claim 1, characterized in that, The detection equipment includes a temperature sensor, a pressure sensor, a seismic detection device, and a flow meter. The temperature sensor is located in the horizontal well, the multi-branch horizontal well, and the U-shaped well to detect the underground temperature in real time. The pressure sensor is located in the horizontal well to detect the pressure of carbon dioxide in the horizontal well. The seismic detection device is located in the horizontal well and the multi-branch horizontal well to record and track earthquakes during the heat extraction process. The flow meter is located in the first gas transmission pipeline, the second gas transmission pipeline, and the U-shaped well to record the input and output flow rates of water and carbon dioxide.

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