CN113236189B - A high-efficiency and non-destructive heat extraction system and method - Google Patents

Abstract

The invention discloses a high-efficiency nondestructive heat-taking geothermal exploitation system and a method, which relate to the technical field of geothermal exploitation and comprise an exploitation well, a recharge well and a horizontal well; the horizontal well is positioned in the water-containing geothermal reservoir; two ends of the horizontal well are respectively communicated with the bottoms of the exploitation well and the recharge well; and a heat exchange mechanism is arranged between the tops of the production well and the recharge well. The invention adopts a U-shaped well mode to directly communicate the injection and production wells, controls the opening and closing of the channel according to the actual development condition of reservoir fractures, does not influence the recharge of recharge water no matter whether the fractures are well developed or not, can drill a plurality of horizontal branch wells at the periphery of the main injection and production channel in order to prevent the temperature of the area at the periphery of the main injection and production channel from being reduced too much, increases the injection and production area, prevents the local temperature from being reduced too fast, can independently control each horizontal branch well through a throttling device arranged in the horizontal branch well, communicates by areas, and exchanges the communicated area and the closed area at intervals so as to recover the temperature of the stratum.

Description

A high-efficiency and non-destructive heat extraction system and method

technical field

The invention relates to the technical field of geothermal exploitation, in particular to a geothermal exploitation system and method for high-efficiency and non-destructive heat extraction.

Background technique

As a renewable and clean resource, geothermal energy is widely distributed in my country, especially hydrothermal geothermal energy is widely used. Hydrothermal geothermal is mainly used in power generation, heating, medical bathing and other fields. The main mining technologies are high temperature dry (wet) steam power generation technology, heat pump technology, and cascade utilization technology. The above technologies are used to solve the problems of geothermal wastewater treatment, improvement or restoration of thermal storage. The heat generation capacity, maintaining the fluid pressure of the heat storage, and preventing the land subsidence caused by the reduction of the heat storage pressure, all adopt the technology of combining geothermal irrigation and mining. The difficulty of the combination of irrigation and production is effective recharge. The connection between the recharge well and the exploitation well depends entirely on the fractures of the reservoir. The farther the distance is, the worse the connectivity of the fractures, so 100% recharge cannot be achieved, which inevitably causes The thermal storage pressure decreases and the ground subsides.

SUMMARY OF THE INVENTION

Based on the problem that recharge is difficult or even impossible in the prior art, the present invention proposes an efficient and non-destructive geothermal exploitation method and system, which can effectively solve the geothermal exploitation combined with irrigation and exploitation.

For achieving the above object, the present invention provides the following scheme:

The invention provides a high-efficiency and non-destructive heat-extracting geothermal exploitation system, comprising a exploitation well, a recharge well and a horizontal well; the horizontal well is located in a water-bearing geothermal reservoir; two ends of the horizontal well are respectively connected to the exploitation well and the The bottom of the recharge well is communicated; a heat exchange mechanism is arranged between the exploitation well and the top of the recharge well.

Optionally, a choke device is provided in the middle of the horizontal well.

Optionally, the horizontal well includes a plurality of horizontal lateral wells.

Optionally, each horizontal branch well is provided with a choke device.

Optionally, the horizontal well communicates with formation fractures.

Optionally, a lift pump is provided in the vertical mining section, and the outlet end of the lift pump communicates with the inlet end of the heat exchange mechanism.

Optionally, a filter device is provided between the lift pump and the heat exchange mechanism. A method for efficient and non-destructive heat extraction and geothermal exploitation, the water circulation in the water-bearing geothermal reservoir is controlled as follows:

Single main irrigation and production well mode;

(1) The throttling device is closed, and the fissure circulates;

For well-developed fractures in the water-bearing geothermal reservoir, the throttling device is closed, so that the recharged water will flow into the surrounding water-bearing geothermal reservoir through the fractures after entering the horizontal well.

(2) The throttling device is opened, and the main channel circulates;

For the case where the fractures of the water-bearing geothermal reservoir are not well developed, the throttling device is opened to connect the horizontal well, and the opening size of the throttling device is judged according to the water level change of the recharge well and the pressure difference with the production well. If the water level of the recharge well rises, it proves that there is resistance to the recharge, and the water level stops changing after a certain distance rise, indicating that the recharge well can still recharge smoothly although the recharge resistance has increased; if the water level of the recharge well continues to rise, the pressure difference will increase. If it is large, it means that the fissure is seriously blocked. At this time, it is necessary to increase the opening degree of the throttling device and increase the flow area of the horizontal well;

Main irrigation and production well + horizontal lateral well mode;

(1) All channels of horizontal branch wells are closed;

For reservoirs with well-developed water-bearing geothermal reservoirs, all throttling devices are closed to monitor the water level of the recharge well and the pressure difference between the production well and the recharge well during the production and irrigation process. The water level does not change or rises very little. , the pressure difference is small, this scheme is adopted;

(2) The channel of the horizontal branch well is partially opened;

When it is found that the pressure difference between the production well and the recharge well increases or the water level of the recharge well rises a lot, it proves that the recharge fissure is blocked. At this time, the throttling device in some horizontal branch wells is opened, and the opening degree changes according to the water level of the recharge well. and the pressure difference change; in order to ensure that the temperature of the pumped water is basically constant, the horizontal branch wells are opened in different areas, and replaced after a certain period of time, so that the pumped formation has enough time for temperature recovery;

(3) All channels of horizontal branch wells are opened;

When the recharge rate of the partially opened horizontal branch well channel decreases, all the channels of the horizontal branch well are opened to satisfy all the irrigation and production channels unimpeded.

The present invention has achieved the following technical effects with respect to the prior art:

The present invention adopts the mode of U-shaped well, which directly connects the irrigation and production wells, and controls the opening and closing of the channel according to the actual situation of the development of reservoir fractures. The temperature of the area around the production channel has dropped too much, and several horizontal branch wells can be drilled around the main irrigation and production channel to increase the irrigation and production area and prevent the local temperature from dropping too quickly. The horizontal and branched wells are individually controlled and connected in different areas, and the connected area and the closed area are exchanged at intervals to restore the formation temperature.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic structural diagram of a high-efficiency and non-destructive heat extraction geothermal mining system of the present invention;

Fig. 2 is the structural representation of the horizontal branch of a kind of high-efficiency and non-destructive heat extraction geothermal exploitation system of the present invention;

Fig. 3 is a kind of high-efficiency and non-destructive heat extraction geothermal exploitation system U-shaped well structure schematic diagram of the present invention;

FIG. 4 is a schematic diagram of another U-shaped well structure of a high-efficiency and non-destructive heat extraction geothermal exploitation system of the present invention.

Description of reference numerals: 1. Production well; 1-1. Production vertical section; 1-2. Production horizontal section; 2. Recharge well; 2-1. Recharge vertical section; 2-2 Recharge horizontal section; 3 4. Throttle device; 5. Monitoring device; 6. Lift pump; 7. Heat exchanger; 8. Heat pump; 9. Filter device; 10. Casing; 11. Thermal insulation pipe.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

As shown in FIG. 1 , this embodiment provides a high-efficiency and non-destructive heat extraction geothermal exploitation system, including a exploitation well 1, a recharge well 2 and a horizontal well; the horizontal well is located in a water-bearing geothermal reservoir; two of the horizontal wells The ends are respectively communicated with the bottoms of the exploitation well 1 and the recharge well 2 ; a heat exchange mechanism is arranged between the tops of the exploitation well 1 and the recharge well 2 .

In this specific embodiment, a choke device 4 is provided in the middle of the horizontal well, the choke device 4 is a choke valve, the choke valve is electrically connected with the monitoring device 5, and a pressure sensor is arranged inside the choke valve, and the choke valve passes through the pressure sensor. Monitor the pressure on the side of the production well 1 and the pressure on the side of the recharge well 2; the monitoring device 5 is set on the ground, and the pressure of the production well 1 and the recharge well 2 can be known through the monitoring device 5, and the opening of the choke valve can be controlled degrees and off. The horizontal well is an open hole and communicates with the formation fracture. A lift pump 6 is arranged in the vertical mining section 1-1, and a filter device 9 is arranged at the outlet end of the lift pump 6, and the filter device communicates with the inlet end of the heat exchange mechanism.

Further, the lift pump 6 is placed in the water-containing geothermal reservoir, the water pumping pipeline adopts the thermal insulation pipe 11, and the pipeline between the lift pump 6 and the filter device 9 is the thermal insulation pipe, which can prevent the hot water being extracted. Temperature dropped too fast. The well wall above the water-bearing geothermal reservoir is protected by the casing 10 .

Embodiment 2:

As shown in Figure 2, in order to prevent the temperature around the open-hole section of a single horizontal well from dropping too much, it is necessary to increase the irrigation and production area, and increase the flow distance and time of the recharged water in the reservoir after reinjection, so as to ensure that the temperature of the pumped water is basically constant. The horizontal well is set into a plurality of horizontal branch wells 3, and each horizontal branch well 3 communicates with its surrounding fissures, so that an interconnected network structure can be formed, and the exploitation area and recharge area of the geothermal reservoir can be increased. A throttling device 4 is installed in each horizontal lateral well 3, and the opening degree of the throttling device 4 is selectively adjusted and controlled by the change of the temperature of the pumped water and the pressure difference between the irrigation and production wells displayed by the monitoring device.

Embodiment three:

This embodiment discloses a method based on the high-efficiency and non-destructive heat extraction geothermal exploitation system in the first embodiment, and the water circulation control in the water-bearing geothermal reservoir is as follows:

Single main irrigation and production well mode;

(1) The throttling device 4 is closed, and the fissure circulates;

For the well-developed water-bearing geothermal reservoir, the throttling device 4 is closed, so that the recharged water will flow into the surrounding water-bearing geothermal reservoir through the fracture after entering the horizontal well. fissure;

(2) The throttling device 4 is opened, and the main channel circulates;

For the case where the fractures of the water-bearing geothermal reservoir are not well developed, the throttling device 4 is opened to connect the horizontal well, and the opening size of the throttling device 4 is judged according to the change of the water level of the recharge well 2 and the pressure difference with the production well 1. If the water level of the recharge well 2 rises, it proves that there is resistance to the recharge, and the water level stops changing after a certain distance rise, indicating that the recharge well 2 can still recharge smoothly although the recharge resistance has increased. The water level continues to rise and the pressure difference increases, indicating that the fissures are seriously blocked. At this time, it is necessary to increase the opening degree of the throttling device 4 to increase the flow area of the horizontal well.

Embodiment 4:

The present embodiment discloses a method based on the high-efficiency and non-destructive heat extraction geothermal exploitation system in the second embodiment, the main irrigation and production well+horizontal lateral well 3 modes;

(1) All three channels of horizontal branch wells are closed;

For reservoirs with well-developed water-bearing geothermal reservoirs, all closed throttling devices 4 monitor the water level of the recharge well 2 and the pressure difference between the production well 1 and the recharge well 2 during the production and filling process, and the water level does not change or If the amount of increase is small and the pressure difference is small, this scheme is adopted;

(2) The 3 channels of the horizontal branch well are partially opened;

When it is found that the pressure difference between the production well 1 and the recharge well 2 increases or the water level of the recharge well 2 rises more, it proves that the recharge fissures are blocked. Adjust according to the change of water level and pressure difference in recharge well 2; in order to ensure that the temperature of the pumped water is basically constant, the horizontal branch well is opened in three areas, and replaced after a certain period of time, so that the pumping formation has enough time for temperature recovery;

(3) All three channels of horizontal branch wells are opened;

When the recharge rate of the partially opened horizontal branch well 3 channels decreases, all channels of the horizontal branch well 3 are opened to satisfy all the irrigation and production channels unimpeded.

Embodiment 5:

As shown in FIG. 3 , in this embodiment, both the production well 1 and the recharge well 2 are in the form of horizontal wells, and the butt joint is the horizontal section of the two wells.

Embodiment 6:

As shown in FIG. 4 , in this embodiment, in the production well 1 and the recharge well 2, one well is a vertical well, the other well is a horizontal well, and the butt joint is the junction of the horizontal section and the vertical section.

It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. . Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes that come within the meaning and range of equivalents of , are intended to be embraced within the invention, and any reference signs in the claims shall not be construed as limiting the involved claim.

In this specification, specific examples are used to illustrate the principles and implementations of the present invention, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention; There will be changes in the specific implementation manner and application scope of the idea of the invention. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (1)

1. a method for high-efficiency and non-destructive thermal geothermal exploitation, it is characterized in that, comprises exploitation well, recharge well and horizontal well; Described horizontal well is located in water-bearing geothermal reservoir; The bottom of the exploitation well is communicated with the recharge well; a heat exchange mechanism is arranged between the top of the exploitation well and the recharge well; a choke device is arranged in the middle of the horizontal well; the horizontal well is connected to the formation fissure Connected; the water circulation in the water-bearing geothermal reservoir is controlled as follows: single main irrigation and production well mode; (1) The throttling device is closed, and the fissure circulates; For well-developed fractures in the water-bearing geothermal reservoir, the throttling device is closed, so that the recharged water will flow into the surrounding water-bearing geothermal reservoir through the fractures after entering the horizontal well. (2) The throttling device is opened, and the main channel circulates; For the case where the fractures of the water-bearing geothermal reservoir are not well developed, the throttling device is opened to connect the horizontal well, and the opening size of the throttling device is judged according to the water level change of the recharge well and the pressure difference with the production well. If the water level of the recharge well rises, it proves that there is resistance to the recharge, and the water level stops changing after a certain distance rise, indicating that the recharge well can still recharge smoothly although the recharge resistance has increased; if the water level of the recharge well continues to rise, the pressure difference will increase. If it is large, it means that the fissure is seriously blocked. At this time, it is necessary to increase the opening degree of the throttling device to increase the flow area of the horizontal well; Main irrigation and production well + horizontal branch well mode; the horizontal well includes a plurality of horizontal branch wells; each horizontal branch well is provided with a choke device; (1) All channels of horizontal branch wells are closed; For reservoirs with well-developed water-bearing geothermal reservoirs, all throttling devices are closed to monitor the water level of the recharge well and the pressure difference between the production well and the recharge well during the production and irrigation process. The water level does not change or rises very little. , the pressure difference is small, this scheme is adopted; (2) The channel of the horizontal branch well is partially opened; When it is found that the pressure difference between the production well and the recharge well increases or the water level of the recharge well rises a lot, it proves that the recharge fissure is blocked. At this time, the throttling device in some horizontal branch wells is opened, and the opening degree changes according to the water level of the recharge well. and the pressure difference change; in order to ensure that the temperature of the pumped water is basically constant, the horizontal branch wells are opened in different areas, and replaced after a certain period of time, so that the pumped formation has enough time for temperature recovery; (3) All channels of horizontal branch wells are opened; When the recharge rate of the partially opened horizontal branch well channel decreases, all the channels of the horizontal branch well are opened to satisfy all the irrigation and production channels unimpeded.

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