A method for mining underground water-dissolved helium

Abstract

The invention discloses a method for exploiting underground water-dissolved helium in the technical field of helium development, comprising the following steps: determining an effective trap of helium-rich formation water and the flow direction of underground water; injecting a carrier gas into the lower part of the trap so that helium is desolvated from water into the carrier gas at the gas-water interface; the carrier gas naturally migrates to the top of the water trap to form a helium-rich gas reservoir; and drilling a well at the top of the trap to exploit the helium-rich gas reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of helium development, and in particular to a method for exploiting underground water-dissolved helium. Background Art

[0002] Helium is a colorless, odorless, inert monatomic gas that can be used in aerospace, medical care, and as a lift source for meteorological and other observation balloons. It has a wide range of uses.

[0003] As helium is included in the list of strategic materials by more and more countries and regions, the import channels of helium have been restricted. However, Shaanxi, Shanxi, Tibet and other places in my country have rich water-soluble helium resources. The domestic water-soluble helium resources account for about 31% of the total helium resources in my country.

[0004] At present, the exploitation of groundwater-dissolved helium in China has always been to extract helium-rich formation water to the ground and then use various technologies to extract helium. The groundwater after helium extraction also needs to be reinjected into the formation, which is very costly and does not have the ability to exploit helium on a large scale. Summary of the invention

[0005] The purpose of the present invention is to provide a method for exploiting underground water-soluble helium to solve the technical problem that the prior art is not capable of large-scale exploitation of helium.

[0006] In order to solve the above technical problems, the present invention specifically provides a method for exploiting underground water-soluble helium, comprising the following steps:

[0007] Determine effective trapping of helium-rich formation water;

[0008] Injecting a carrier gas into the trapped groundwater to cause helium to desolventize from the water into the carrier gas at the gas-water interface;

[0009] The carrier gas will naturally migrate to the top of the water trap to form a helium-rich gas reservoir;

[0010] Wells were drilled at the top of the trap to exploit the helium-rich gas reservoir.

[0011] As a preferred embodiment of the present invention, the method for determining the effective trapping of helium-rich formation water and the groundwater flow direction is:

[0012] Use geological, geophysical, geochemical and drilling methods to determine the distribution range of helium-rich formation water;

[0013] Use techniques including structural interpretation and reservoir inversion to implement effective traps within the distribution range of geothermal water;

[0014] Methods and techniques including dilution method, groundwater analysis tool set, numerical simulation software, groundwater velocity and direction instrument and three-point method are preferred to determine the flow direction of groundwater in effective traps and adjacent areas.

[0015] As a preferred embodiment of the present invention, the method of injecting carrier gas into the trap is:

[0016] If the groundwater is immobile, a well is drilled from the lower part of the trap and carrier gas is injected into the helium-rich groundwater layer through the well;

[0017] If the groundwater is flowing water, a well is drilled from the upstream part of the groundwater flow, and the carrier gas is injected into the helium-rich groundwater layer through the well.

[0018] As a preferred embodiment of the present invention, the carrier gas may be nitrogen, methane or carbon dioxide;

[0019] After the carrier gas is injected and the gas cap is formed, the formation water temperature is lowered through a heat exchange device to assist the precipitation of helium.

[0020] As a preferred embodiment of the present invention, the carrier gas is carbon dioxide, and the source equipment of the carbon dioxide includes a coal-fired boiler and a cement kiln, so that the carbon dioxide gas reservoir can be sealed in a closed trap while helium is mined, thereby achieving the purpose of carbon reduction.

[0021] As a preferred embodiment of the present invention, after the carbon dioxide is discharged from the source equipment, impurities in the carbon dioxide are removed by chemical and / or physical methods through a purification device, and then the carbon dioxide is injected into the enclosure through a straight pipe connecting the enclosure and the purification device.

[0022] As a preferred solution of the present invention, a gas storage tank is provided on the straight pipe, and valves are provided at both the inlet and outlet ends of the gas storage tank;

[0023] When the source equipment is working and carbon dioxide needs to be injected into the trap, the valves at the inlet and outlet ends of the gas storage tank are opened;

[0024] When the source equipment is working but it is not necessary to inject carbon dioxide into the trap, the valve at the outlet is closed and the valve at the inlet is opened;

[0025] When the source equipment is not working but CO2 needs to be injected into the trap, the valve at the outlet is opened and the valve at the inlet is closed.

[0026] As a preferred solution of the present invention, a compressor is arranged at the inlet end of the gas storage tank to compress the incoming carbon dioxide into the gas storage tank to increase the amount of carbon dioxide that the gas storage tank can accommodate.

[0027] As a preferred solution of the present invention, a plurality of gas storage tanks are provided, and the plurality of gas storage tanks are connected in parallel with each other, a straight pipe is used as a main pipe, an inlet end and an outlet end of each gas storage tank are respectively connected to an upstream straight pipe and a downstream straight pipe through a branch pipe, and a valve is provided on each branch pipe;

[0028] As a preferred solution of the present invention, a first heat exchanger is provided on the upstream straight pipe for absorbing the heat released when the carbon dioxide is compressed to reduce the temperature of the carbon dioxide;

[0029] An expander is provided on the downstream straight-through pipe to convert the high-pressure carbon dioxide in the gas storage tank into low-pressure and low-temperature carbon dioxide to improve the efficiency of helium precipitation from the formation water.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention deploys two or more wells near the helium-rich formation water trap according to actual needs, injects carrier gas into the trap, uses the carrier gas to extract the helium dissolved in the formation water, and transports it to the high part of the trap to form a helium-rich gas reservoir, and then drills wells at the high part of the trap to exploit the helium-rich gas reservoir. This method is suitable for large-scale exploitation of helium. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0033] Figure 1 This is a schematic diagram of helium distribution during water-soluble helium mining in the present invention;

[0034] Figure 2 Schematic diagram of a carbon dioxide treatment device in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the 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 described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The present invention specifically provides a method for exploiting underground water-soluble helium, comprising the following steps:

[0037] Determine effective trapping of helium-rich formation water;

[0038] Injecting a carrier gas into the trapped groundwater to cause helium to desolventize from the water into the carrier gas at the gas-water interface;

[0039] The carrier gas will naturally migrate to the top of the water trap to form a helium-rich gas reservoir;

[0040] Wells were drilled at the top of the trap to exploit the helium-rich gas reservoir.

[0041] The concept of trap: A place suitable for oil and gas accumulation and formation of oil and gas reservoirs is called a trap.

[0042] A trap consists of three parts: (1) reservoir rock; (2) cap rock; and (3) an obstruction that prevents the continued migration of oil and gas and causes the accumulation of oil and gas. It can be a bending deformation of the cap rock itself, such as an anticline, or another obstruction, such as a fault or lithology change.

[0043] In short, a trap is an effective space that can capture dispersed hydrocarbons to form oil and gas accumulations and has the ability to store oil and gas, but not all oil and gas are contained in the trap. Once a sufficient amount of oil and gas enters the trap, fills the trap or occupies part of the trap, an oil and gas reservoir can be formed.

[0044] Helium is mainly produced in ancient sedimentary rocks and granites in the basement, and is formed through the decay of thorium and uranium. When the temperature exceeds the sealing temperature of the helium source rock, helium is released from the source rock and migrates upward along deep and large fault channels.

[0045] The principle of helium desolvation from water into carrier gas at the gas-water interface is as follows: carrier gas is injected into the helium-rich groundwater layer. As the injection volume increases, after the groundwater solubility is met, the injected carrier gas exists in a free state and gathers into a gas reservoir at the top of the trap under the action of buoyancy; because the partial pressure of helium in the carrier gas is much lower than the partial pressure in groundwater, helium is displaced at the gas-water interface and dissolved in the gas reservoir, forming a helium-rich gas reservoir (in accordance with Henry's law).

[0046] The present invention deploys two or more wells near the helium-rich formation water trap according to actual needs, injects carrier gas into the trapped helium-rich groundwater layer, uses the carrier gas to extract the helium dissolved in the formation water, and transports it to the high part of the trap to form a helium-rich gas reservoir, and then drills wells in the high part of the trap to exploit the helium-rich gas reservoir. The method is low-cost and suitable for large-scale exploitation of helium.

[0047] At present, no one has used this gas injection and displacement method for mining. If helium can be extracted using this method, it will be a good choice for water-soluble helium mining in my country, especially using carbon dioxide mining.

[0048] Furthermore, the method for determining the effective trapping of helium-rich formation water and the groundwater flow direction is as follows:

[0049] Use geological, geophysical, geochemical and drilling methods to determine the distribution range of helium-rich formation water;

[0050] Use techniques including structural interpretation and reservoir inversion to implement effective traps within the distribution range of geothermal water;

[0051] Methods and techniques including dilution method, groundwater analysis tool set, numerical simulation software, groundwater velocity and direction instrument and three-point method are preferred to determine the flow direction of groundwater in effective traps and adjacent areas.

[0052] Further, the method of injecting carrier gas into the trap is:

[0053] If the groundwater is immobile, a well is drilled from the lower part of the trap and carrier gas is injected into the helium-rich groundwater layer through the well;

[0054] If the groundwater is flowing water, a well is drilled from the upstream part of the groundwater flow, and the carrier gas is injected into the helium-rich groundwater layer through the well.

[0055] Further, the carrier gas may be nitrogen, methane or carbon dioxide;

[0056] Since low temperature can help helium precipitation, after the carrier gas is injected and the gas cap is formed, the formation water temperature is lowered through a heat exchange device to help helium precipitation.

[0057] Specifically, a U-shaped well may be arranged in the formation water, that is, a U-shaped pipeline is set up, with both ends of the pipeline located on the ground, and the formation water is cooled by injecting a cooling medium into the pipeline.

[0058] Furthermore, considering the direction of carbon reduction and emission reduction, and carbon dioxide can be used as a carrier gas, the carrier gas is preferably carbon dioxide in the present invention;

[0059] The carbon dioxide is derived from waste gas emitted by various factories, including coal-fired boilers, cement kilns, etc., so that while exploiting helium, the gas reservoir formed by carbon dioxide can be sealed in a closed trap to achieve the purpose of carbon reduction.

[0060] Furthermore, in order to avoid reducing the helium precipitation efficiency due to insufficient purity of carbon dioxide in the exhaust gas, the present invention adopts the following measures:

[0061] After the carbon dioxide is discharged from the source equipment, impurities in the carbon dioxide are removed by a purification device using a chemical and / or physical method, and then the carbon dioxide is injected into the enclosure through a straight pipe connecting the enclosure and the purification device.

[0062] Furthermore, considering that the source equipment and the carrier gas injection may be out of sync, the present invention provides a gas storage tank on the straight pipe, and valves are provided at both the inlet and outlet ends of the gas storage tank;

[0063] When the source equipment is working and carbon dioxide needs to be injected into the enclosure, the valves at the inlet and outlet ends of the gas storage tank are both opened, so that carbon dioxide is directly injected into the enclosure;

[0064] When the source equipment is working but there is no need to inject carbon dioxide into the trap, the valve at the outlet is closed and the valve at the inlet is opened, so that the carbon dioxide emitted by the source equipment is temporarily stored in the gas storage tank for standby use;

[0065] When the source equipment is not working but CO2 needs to be injected into the trap, the valve at the outlet is opened and the valve at the inlet is closed.

[0066] Furthermore, a compressor is provided at the inlet end of the gas storage tank for compressing the incoming carbon dioxide into the gas storage tank to increase the amount of carbon dioxide that the gas storage tank can accommodate.

[0067] Furthermore, in order to further increase the maximum storage capacity of carbon dioxide, multiple gas storage tanks are provided, and the multiple gas storage tanks are connected in parallel with each other, a straight pipe is used as the main pipeline, and the inlet and outlet ends of each gas storage tank are respectively connected to the upstream straight pipe and the downstream straight pipe through branch pipes, and each branch pipe is provided with a valve.

[0068] Furthermore, a first heat exchanger is provided on the upstream straight pipe for absorbing heat released when the carbon dioxide is compressed to reduce the temperature of the carbon dioxide;

[0069] An expander is provided on the downstream straight-through pipe for converting the high-pressure carbon dioxide in the gas storage tank into low-pressure and low-temperature carbon dioxide.

[0070] Low-temperature carbon dioxide can be used as a cooling material to reduce the temperature of formation water to a certain extent, so as to improve the efficiency of helium precipitation from formation water; at the same time, the carbon dioxide pressure passing through the expander is relatively low, which can also help the precipitation of helium.

[0071] The above embodiments are merely exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims.

[0072] Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A method for exploiting underground water-soluble helium, characterized in that: The following steps are involved: Determine effective trapping of helium-rich formation water; Injecting a carrier gas into the trapped groundwater to cause helium to desolventize from the water into the carrier gas at the gas-water interface; The carrier gas will naturally migrate to the top of the water trap to form a helium-rich gas reservoir; Drilling wells at the top of the trap to exploit the helium-rich gas reservoir; The carrier gas is carbon dioxide, and the source equipment of the carbon dioxide includes coal-fired boilers and cement kilns, so that the carbon dioxide gas reservoir can be sealed in a closed trap while helium is mined, thereby achieving the purpose of carbon reduction; After the carbon dioxide is discharged from the source equipment, impurities in the carbon dioxide are removed by chemical and / or physical methods through a purification device, and then the carbon dioxide is injected into the trap through a straight pipe connecting the trap and the purification device; The straight-through pipe is provided with a gas storage tank, and the inlet and outlet ends of the gas storage tank are both provided with valves; When the source equipment is working and carbon dioxide needs to be injected into the trap, the valves at the inlet and outlet ends of the gas storage tank are opened; When the source equipment is working but it is not necessary to inject carbon dioxide into the trap, the valve at the outlet is closed and the valve at the inlet is opened; When the source equipment is not working, but CO2 needs to be injected into the trap, the valve at the outlet is opened and the valve at the inlet is closed; A compressor is arranged at the inlet end of the gas storage tank to compress the incoming carbon dioxide into the gas storage tank to increase the amount of carbon dioxide that the gas storage tank can accommodate; There are multiple gas storage tanks, and the multiple gas storage tanks are connected in parallel. The straight pipe is used as the main pipeline. The inlet and outlet ends of each gas storage tank are connected to the upstream straight pipe and the downstream straight pipe through branch pipelines, respectively, and each branch pipeline is provided with a valve; A first heat exchanger is provided on the upstream straight pipe, which is used to absorb the heat released when the carbon dioxide is compressed to reduce the temperature of the carbon dioxide; An expander is provided on the downstream straight-through pipe to convert the high-pressure carbon dioxide in the gas storage tank into low-pressure and low-temperature carbon dioxide, so as to improve the efficiency of helium precipitation from the formation water.

2. A method for exploiting underground water-soluble helium according to claim 1, characterized in that: The method to determine the effective trapping of helium-rich formation water and the direction of groundwater flow is: Use geological, geophysical, geochemical and drilling methods to determine the distribution range of helium-rich formation water; Use techniques including structural interpretation and reservoir inversion to implement effective trapping within the groundwater distribution range; Methods and techniques including dilution method, groundwater analysis tool set, numerical simulation software, groundwater velocity and direction instrument and three-point method are used to determine the flow direction of groundwater in effective traps and adjacent areas.

3. A method for exploiting underground water-soluble helium according to claim 2, characterized in that: The method of injecting carrier gas into the trap is: If the groundwater is immobile, a well is drilled from the lower part of the trap and carrier gas is injected into the helium-rich groundwater layer through the well; If the groundwater is flowing water, a well is drilled from the upstream part of the groundwater flow, and the carrier gas is injected into the helium-rich groundwater layer through the well.

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