A geothermal well anti-scaling and descaling method

Abstract

The present invention discloses a method for preventing and removing scale from a geothermal well, and relates to the technical field of preventing and removing scale from a geothermal well. The present invention is used for a geothermal well and comprises: a submersible pump, a vapor-liquid separator, a compressor, and a CO2 gas source. The submersible pump is arranged in the geothermal water of the geothermal well; one end of the vapor-liquid separator inlet is connected to the submersible pump, one end of the liquid outlet is connected to a liquid regulating valve, and one end of the gas outlet is connected to a gas regulating valve; one end of the compressor inlet is connected to the downstream end of the gas regulating valve, and one end of the gas outlet is connected to a position lower than the scaling position of the geothermal well; and the CO2 gas source outlet is connected to one end of the compressor inlet, and the CO2 gas source outlet is provided with a pressure reducing valve. The present invention ensures that a sufficient CO2 content is always maintained in the geothermal fluid, preventing CaCO3 scaling from forming, and can even eliminate previously formed calcium scale.

Description

Technical Field

[0001] The present invention relates to the technical field of geothermal well anti-scaling and descaling, and in particular to a geothermal well anti-scaling and descaling system and a method for anti-scaling and descaling using CO2 gas. Background Art

[0002] Geothermal energy, a renewable energy source, boasts vast reserves and relatively high stability compared to other renewable energy sources such as solar and wind power. However, scaling of pipelines and equipment encountered during geothermal development, particularly hydrothermal development, presents a significant challenge and hinders the efficient and cost-effective development of geothermal resources. The main types of scaling in geothermal power plants include calcium scale, silica scale, metal oxide scale, and fine particles, sludge, microorganisms, and sulfides contained in the geothermal fluid. Calcium scaling is primarily pressure-related and typically occurs near the flash point, caused by a decrease in wellbore pressure. Flashing causes large amounts of CO2 to precipitate, which in turn reduces the acidity of the brine and leads to supersaturation of calcium carbonate, resulting in the formation of calcium scale. Furthermore, CaCO3 scale clogging is a common phenomenon during geothermal tailwater recharge. Within a single well, it can occur at the bottom, surface, and in pipelines, significantly reducing the efficiency of geothermal energy. Current methods for preventing and removing scale primarily involve adding chemical reagents, such as acid, to the well or performing mechanical descaling. Chemical descaling has the problems of high cost and water pollution. Mechanical descaling requires stopping geothermal well production and carrying out special construction work, which is also costly. Therefore, it is necessary to find a more economical and reasonable anti-scaling and descaling method. Summary of the Invention

[0003] In response to the deficiencies in the prior art, the present invention provides a geothermal well anti-scaling and descaling system and a method for anti-scaling and descaling using CO2 gas. In geothermal well sections that may have previously been scaled, the CO2 gas source is used to supplement CO2 gas for leakage during the initial operation and long-term operation of the system. A sufficient CO2 content is always maintained in the geothermal fluid, preventing the formation of CaCO3 scale and even eliminating previously formed calcium scale, thereby solving the problems of high cost and environmental pollution of the prior art.

[0004] To achieve the above objectives, the present invention can be implemented through the following technical solutions:

[0005] A geothermal well anti-scaling and descaling system, used for a geothermal well, comprising:

[0006] A vapor-liquid separator, one end of which is connected to the geothermal well through its inlet, one end of which is connected to a liquid regulating valve through its liquid outlet, and one end of which is connected to a gas regulating valve through its gas outlet;

[0007] a compressor, one end of its air inlet being connected to the downstream end of the gas regulating valve, and one end of its air outlet being connected to a scaling position lower than the geothermal well; and

[0008] The gas outlet of the CO2 gas source is connected to one end of the gas inlet of the compressor and the gas outlet of the CO2 gas source is provided with a pressure reducing valve.

[0009] The geothermal well anti-scaling and descaling system as described above further includes a submersible pump, which is arranged in the geothermal water of the geothermal well, and one end of the inlet of the gas-liquid separator is connected to the submersible pump.

[0010] A method for preventing and removing scale in geothermal wells using CO2 gas, used in the geothermal well prevention and removal system as described above, comprising:

[0011] The gas-liquid mixture is sucked out of the geothermal well by a submersible pump and enters a gas-liquid separator, wherein the gas-liquid mixture includes at least CO2;

[0012] The gas-liquid separator separates the gas-liquid mixture into gas and liquid, wherein the liquid is supplied to the user through the liquid regulating valve, and the gas passes through the gas regulating valve and then re-enters the position below the scaling position of the geothermal well under the pressure of the compressor.

[0013] As described above, the method for preventing and removing scale from geothermal wells using CO2 gas, further comprises the following steps: the CO2 gas source is used to supply CO2 gas during the initial startup of the system, and the CO2 gas leaked during the operation of the system is replenished, so that the gas-liquid mixture always maintains a sufficient CO2 content to prevent the formation of CaCO3 scale.

[0014] As described above, in the method for preventing and removing scale from geothermal wells using CO2 gas, the gas-liquid mixture is a geothermal fluid containing non-condensable gas.

[0015] The above-mentioned method for preventing and removing scale in geothermal wells using CO2 gas further adjusts the opening ratio of the gas regulating valve and the liquid regulating valve so that the liquid level of the gas-liquid separator is maintained at an intermediate position.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] In the geothermal well section that was originally likely to be scaled in the present invention, the CO2 gas source is used to replenish the CO2 gas for leakage during the initial operation and long-term operation of the system. The geothermal fluid always maintains a sufficient CO2 content, so that CaCO3 scaling can never be formed, and even the calcium scale formed previously can be eliminated, thereby solving the problems of high cost and environmental pollution of the existing technology.

[0018] The present invention has a reasonable and simple structure. CO2 is a natural gas, environmentally friendly and non-toxic. CO2 is weakly corrosive when dissolved in water and will not damage system equipment. The separator allows most of the gas to be recycled, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 It is a structural schematic diagram of a geothermal well anti-scaling and descaling system in an embodiment of the present invention.

[0021] Explanation of the accompanying symbols: 1. Geothermal well; 2. Submersible pump; 3. Gas-liquid separator; 4. Liquid regulating valve; 5. Gas regulating valve; 6. Pressure reducing valve; 7. CO2 gas source; 8. Compressor. DETAILED DESCRIPTION

[0022] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] Example:

[0024] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] In the description of the present invention, "plurality" means at least two, such as two or three, unless otherwise specifically defined. Furthermore, unless otherwise specified or defined, the terms "mounted," "connected," and "connected" should be understood broadly, meaning, for example, fixed, removable, or integral; mechanical or electrical; direct or indirect through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention.

[0026] See also Figure 1 , Figure 1 This is a schematic diagram of the geothermal well anti-scaling and descaling system in an embodiment of the present invention. In geothermal well sections previously susceptible to scaling, the system uses a CO2 gas source to replenish CO2 gas during initial system operation and long-term operation. This ensures a sufficient CO2 content in the geothermal fluid, preventing the formation of CaCO3 scale and even eliminating previously formed calcium scale. This addresses the high cost and environmental pollution issues of existing technologies.

[0027] A geothermal well anti-scaling and descaling system, for use in geothermal wells, comprises: a submersible pump, a vapor-liquid separator, a compressor, and a CO2 gas source. The submersible pump is disposed in the geothermal water of the geothermal well; one end of the vapor-liquid separator inlet is connected to the submersible pump, one end of the liquid outlet is connected to a liquid regulating valve, and one end of the gas outlet is connected to a gas regulating valve; one end of the compressor inlet is connected to the downstream end of the gas regulating valve, and one end of the gas outlet is connected to a location below the scale formation of the geothermal well; and the CO2 gas source outlet is connected to one end of the compressor inlet, and the CO2 gas source outlet is provided with a pressure reducing valve. It should be noted that this system is also applicable to pumpless, self-flowing wells. Since the hot water in a pumpless, self-flowing well will emerge without external force, the submersible pump can be omitted and one end of the vapor-liquid separator inlet can be directly connected to the geothermal well.

[0028] The working process of this anti-scaling and descaling system is as follows: geothermal water carrying non-condensable gases such as CO2 is pumped out of the wellhead from the geothermal well 1 through the submersible pump 2 and enters the vapor-liquid separator 3 to separate the vapor and liquid. The liquid is supplied to the heat user through the liquid regulating valve 4, and the gas enters the compressor 8 after passing through the gas regulating valve 5. After reasonable adjustment of the liquid regulating valve 4 and the gas regulating valve 5, the liquid level in the vapor-liquid separator 3 can be kept in the middle position to ensure a good vapor-liquid separation function. The compressor 8 pressurizes the gas and presses it into the well through the pipeline. The depth must exceed the well section where scaling may occur. The scaling location can be obtained through preliminary measurement or calculation simulation. The CO2 gas source 7 supplies CO2 gas during initial startup and replenishes the leaked CO2 gas during subsequent operation, so that the geothermal fluid always maintains a sufficient CO2 content to prevent the formation of CaCO3 scale.

[0029] A method for preventing and removing scale from geothermal wells using CO2 gas is used in the geothermal well prevention and removal system described above, comprising: a gas-liquid mixture is sucked out of the geothermal well by a submersible pump and then enters a gas-liquid separator, wherein the gas-liquid mixture includes at least CO2; the gas-liquid separator separates the gas-liquid mixture into gas and liquid, wherein the liquid is supplied to a user through a liquid regulating valve, and the gas, after passing through the gas regulating valve, re-enters a position below the scaling position of the geothermal well under the pressure of a compressor.

[0030] As an optional implementation, in some embodiments, the CO2 gas source supplies CO2 gas when the system is initially started, and replenishes the leaked CO2 gas during the operation of the system, so that the gas-liquid mixture always maintains a sufficient CO2 content to prevent the formation of CaCO3 scale.

[0031] As an optional implementation, in some embodiments, the gas-liquid mixture is a geothermal fluid with non-condensable gas.

[0032] As an optional implementation, in some embodiments, the opening ratio of the gas regulating valve and the liquid regulating valve is adjusted so that the liquid level of the gas-liquid separator is maintained at an intermediate position.

[0033] The present invention has a reasonable and simple structure. CO2 is a natural gas, environmentally friendly and non-toxic. CO2 is weakly corrosive when dissolved in water and will not damage system equipment. The separator allows most of the gas to be recycled, and the cost is low.

[0034] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0035] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A geothermal well anti-scaling and descaling method for geothermal wells, characterized in that: Geothermal well anti-scaling and descaling system includes: A vapor-liquid separator, one end of which is connected to the geothermal well through its inlet, one end of which is connected to a liquid regulating valve through its liquid outlet, and one end of which is connected to a gas regulating valve through its gas outlet; a compressor, one end of its air inlet being connected to the downstream end of the gas regulating valve, and one end of its air outlet being connected to a position lower than the scaling of the geothermal well; and A CO2 gas source, the gas outlet of which is connected to one end of the gas inlet of the compressor and the gas outlet of the CO2 gas source is provided with a pressure reducing valve; A submersible pump is disposed in geothermal water of a geothermal well, and one end of the inlet of the vapor-liquid separator is connected to the submersible pump; Geothermal well anti-scaling and descaling methods include: The gas-liquid mixture is sucked out of the geothermal well by a submersible pump and enters the gas-liquid separator, and the gas-liquid mixture includes at least CO2; The gas-liquid separator separates the gas-liquid mixture into gas and liquid, wherein the liquid is supplied to the user through the liquid regulating valve, and the gas passes through the gas regulating valve and then re-enters the position below the scaling position of the geothermal well under the pressure of the compressor; the CO2 gas source supplies CO2 gas during the initial startup of the system and replenishes the leaked CO2 gas during the operation of the system, so that the gas-liquid mixture always maintains a sufficient CO2 content to prevent the formation of CaCO3 scale.

2. The geothermal well anti-scaling and descaling method according to claim 1, characterized in that: The gas-liquid mixture is a geothermal fluid containing non-condensable gas.

3. The geothermal well anti-scaling and descaling method according to claim 1, characterized in that: By adjusting the opening ratio of the gas regulating valve and the liquid regulating valve, the liquid level of the gas-liquid separator is kept at the middle position.

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