Method and device for evaluating water-soluble helium extraction capacity of natural gas layer

Abstract

The invention provides a method and a device for evaluating the extraction capability of a natural gas layer to water-soluble helium, belongs to the technical field of oil and gas resource evaluation, and solves the problems that the extraction effect of natural gas to helium under real geological conditions cannot be simulated and the extraction capability cannot be quantitatively evaluated in the prior art. The device comprises a natural gas configuration area, a helium solution configuration area, a blending box and a testing cylinder barrel, at least two blending tanks are arranged in the blending box, one blending tank is communicated with the natural gas configuration area, the other blending tank is communicated with the helium solution configuration area, a piston is arranged in the testing cylinder barrel, and a gas inlet and a gas outlet are formed in the piston. The air outlet hole is connected with gas component detection equipment, and the piston is connected with a pressing device. The device is used for researching a mechanism that underground water soluble helium resources enter a natural gas reservoir, can simulate an extraction action process of natural gas on water soluble helium under the conditions of different temperatures, pressures and mineralization degrees of the natural gas reservoir, and quantitatively evaluates the extraction capacity of the natural gas on the water soluble helium.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas resource evaluation, and particularly relates to a method and device for evaluating the extraction ability of natural gas layers for dissolved helium gas. Background Art

[0002] As a non-renewable resource, helium plays an irreplaceable role in the national defense and high-tech fields due to its unique physical properties. However, the current global annual helium production (about 17×10 8 m 3 ) is less than the demand (about 22×10 8 m 3 ). With the rapid development of high-tech, the supply-demand gap is expanding year by year, and in recent years, the helium price has soared by more than 4 times.

[0003] In recent years, studies have shown that the solubility of helium in formation water is controlled by Henry's law, and its solubility increases with increasing temperature and pressure and decreases with increasing salinity. Some studies have estimated the solubility of helium in ideal states such as pure water based on Henry's law, and conducted experimental simulations on the solubility of helium under the conditions of pure water at 0 - 100 MPa and 5 - 80 °C. It is found that the solubility of helium under formation temperature and pressure conditions is extremely large, and the dissolved capacity of formation water in shale layers exceeds its own cumulative helium production by 4 - 5 orders of magnitude. Helium mainly exists in a dissolved state in formation water. According to Henry's theorem, at the gas-water interface between the aqueous solution of helium and the gas layer, the partial pressure of helium on the natural gas side is extremely low. As the partial pressure of helium suddenly decreases from the aqueous solution to the gas layer, helium gradually enters the natural gas layer from the dissolved state, promoting the "extraction" of dissolved helium by natural gas and realizing the transformation of helium from the dissolved state to the free state in the gas layer. However, the current research is mainly based on the single-factor simulation analysis of temperature or pressure under pure water conditions, and it is still impossible to simulate the extraction effect of natural gas on helium at the gas-water interface under the conditions of natural gas components, different formation temperatures, pressures, and salinities in real geological conditions. At the same time, in practice, the relationship between helium-rich gas reservoirs and the presence of bottom water conditions is not obvious; at the gas-water interface above the formation water unsaturated with helium, the intensity and rate of the "extraction" effect of natural gas on helium have not been quantitatively evaluated, which directly restricts the understanding of the formation mechanism of helium-rich natural gas and the research and development of exploration technologies. Therefore, it is necessary to design a method and device for evaluating the extraction ability of natural gas layers for dissolved helium at the gas-water interface as close as possible to geological conditions. Summary of the Invention

[0004] Aiming at the above problems, the object of the present invention is to provide a method and device for evaluating the extraction ability of natural gas layers for water-soluble helium gas, which is used to study the mechanism of water-soluble helium resources in groundwater entering natural gas layers. The present invention can simulate the extraction process of natural gas for water-soluble helium resources under different temperature, pressure and salinity conditions, and determine the contribution of the extraction of water-soluble helium gas by natural gas to the enrichment of helium gas in the gas layer.

[0005] The technical solution adopted by the present invention is as follows: An evaluation device for the extraction ability of natural gas layers for water-soluble helium gas includes a natural gas configuration area, a helium solution configuration area, a dispensing tank and a test cylinder. At least two dispensing tanks are arranged in the dispensing tank, one of the dispensing tanks is communicated with the natural gas configuration area, and the other dispensing tanks are communicated with the helium solution configuration area. A piston is movably and sealingly arranged in the test cylinder, and an air inlet hole and an air outlet hole communicating with the inside of the piston are opened on the piston. The air inlet hole is communicated with the bottom of the dispensing tank through a pipeline, the air outlet hole is connected with a gas component detection device through a pipeline, and the piston is connected with a pressing device.

[0006] Preferably, the bottom of the test cylinder is communicated with a gas-liquid separator through a pipeline, a first flowmeter is arranged on the pipeline connecting the test cylinder and the gas-liquid separator, and the bottom and the top of the gas-liquid separator are both connected with the gas component detection device through pipelines.

[0007] Preferably, a protective cylinder is sleeved outside the test cylinder, liquid heat-conducting medium is filled in the dispensing tank and the protective cylinder, heating tubes are arranged in the dispensing tank and the protective cylinder, and thermometers for monitoring the temperature of the liquid heat-conducting medium are arranged on the dispensing tank and the protective cylinder.

[0008] Preferably, a heat-insulating layer is arranged outside the dispensing tank and the protective cylinder.

[0009] Preferably, an exhaust pipe is arranged on the top of the dispensing tank.

[0010] Preferably, a first pressure gauge is connected to the top of the dispensing tank.

[0011] Preferably, a second pressure gauge and a second flowmeter are arranged on the pipeline connected to the air outlet hole.

[0012] Preferably, an observation window is arranged on the top of the dispensing tank, and a transparent glass is arranged on the top of the dispensing tank.

[0013] Preferably, the natural gas configuration area includes several gas cylinders, the helium solution configuration area includes a helium gas cylinder and a simulated water tank, there are three groups of helium solution configuration areas for configuring helium gas and simulated water required for low, medium and high concentration helium solutions, and four dispensing tanks are arranged.

[0014] A method for evaluating the extraction capacity of a natural gas layer for water-soluble helium, using the evaluation device, the evaluation method comprising: Inject various gas components of natural gas into the evacuated gas tank according to volume, and sequentially transport each gas to one of the evacuated blending tanks; According to the variation of the solubility of helium in pure water with temperature and pressure, the upper limit of the solubility of helium in formation water is estimated. Then, combined with the structural position of the formation, the historical helium generation of the deep possible helium source rock is estimated according to the historical helium generation calculation formula. The dissolved helium concentration in the formation water is estimated in combination with the rock porosity and water content, and it is used as the low concentration value of the helium solution. Combined with the volume of the blending tank, the corresponding amount of helium and simulated water simulating the salinity of the formation water are respectively injected into the helium tank and the simulated water tank, and the simulated water is first injected into the blending tank, and then helium is injected to obtain a low-concentration helium solution; on the basis of the low-concentration helium solution, combined with the helium abundance in the natural gas layer and the amount of natural gas in the blending tank, the amount of helium to be injected into the medium-concentration helium solution is calculated, and the helium is injected into another group of helium tanks in the helium solution configuration area, and then the simulated water and helium are injected into another blending tank; the high-concentration helium solution takes into account the loss of helium in the geological history and takes the value twice the concentration of the medium-concentration helium solution, and then the simulated water and helium are injected into the remaining blending tank; After all the blending tanks are filled with the corresponding liquids and gases, the heating pipes of the blending boxes are turned on, and the temperature of the blending boxes is raised to the formation temperature through a water bath. When the helium in the blending tank is completely dissolved, the extraction capacity of natural gas for water-soluble helium is tested; Before the test, the chamber under the piston is evacuated, the piston is preheated to the simulated temperature through the heating tube, and then high, medium and low concentration helium solutions are injected into the chamber in turn, and finally natural gas is added; the second pressure gauge monitors the pressure change in the chamber, and then controls the pressing force of the pressing device on the piston to keep the pressure in the chamber stable at the set simulated pressure value during the entire gas injection process. After standing still until the designed sampling time, the collected gas sample is transported to the gas component detection equipment through the pipeline connected to the gas outlet, and the volume of the gas under the formation temperature and pressure state is recorded by the second flowmeter; the gas component detection equipment obtains the extracted helium The amount of helium in the natural gas layer after gasification is calculated, and then the proportion of extracted dissolved helium is calculated; at the same time, the helium solution is discharged from the bottom of the test cylinder, and the volume of the helium solution is obtained by the first flowmeter. The discharged helium solution enters the gas-liquid separator, and the gas component detection equipment estimates the concentration of helium in the helium solution in the test cylinder for the gas separated by the gas-liquid separator and the residual helium concentration in the helium solution. The amount of dissolved helium in the test cylinder and free helium in the gas layer is compared with the total amount of input helium, and the amount of helium extracted by natural gas on the helium solution at different times is evaluated, so as to determine the variation law of the extraction intensity of natural gas on helium and its extraction rate.

[0015] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: The present invention is used to study the mechanism of the entry of dissolved helium resources in groundwater into natural gas reservoirs. The present invention can simulate the extraction process of dissolved helium resources in natural gas under different temperature, pressure, and salinity conditions, and determine the contribution of the extraction of dissolved helium in natural gas to the enrichment of helium in the gas reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a schematic flow chart provided for the embodiments of the present invention.

[0018] Reference numerals: 1 - natural gas configuration area; 101 - gas tank; 2 - helium solution configuration area; 201 - helium gas tank; 202 - simulated water tank; 3 - compressor; 4 - dispensing box; 5 - observation window; 6 - exhaust pipe; 7 - first pressure gauge; 8 - thermometer; 9 - dispensing tank; 10 - heating pipe; 11 - first flow meter; 12 - stress pad; 13 - second pressure gauge; 14 - piston; 15 - gas-liquid separator; 16 - second flow meter; 17 - test cylinder; 18 - protection cylinder; 19 - support frame; 20 - intake hole; 21 - outlet hole; 22 - gas component detection device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention claimed, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0022] The following Figure 1 will make a detailed description of the present invention.

[0023] Embodiment: An evaluation device for the extraction ability of water-soluble helium gas from a natural gas layer, as Figure 1 shown, includes a natural gas configuration area 1, a helium solution configuration area 2, a mixing tank 4, and a test cylinder 17. At least two mixing tanks 9 are provided in the mixing tank 4. One of the mixing tanks 9 is communicated with the natural gas configuration area 1, and the other mixing tanks 9 are communicated with the helium solution configuration area 2. A piston 14 is movably and sealingly arranged in the test cylinder 17. An air inlet hole 20 and an air outlet hole 21 communicating with the inside of the piston 14 are opened on the piston 14. The air inlet hole 20 is communicated with the bottom of the mixing tank 9 through a pipeline, and the air outlet hole 21 is connected with a gas component detection device 22 through a pipeline. The piston 14 is connected with a pressing device.

[0024] The natural gas configuration area 1 includes several gas tanks 101. The number of gas tanks 101 is the same as the types of gases in the natural gas. The natural gas configuration area 1 inputs relevant gases into the gas tanks 101 respectively according to the actual types of gases in the natural gas. According to the components of the gas and the water saturation of the formation water, the number of times of filling each gas tank 101 with its corresponding gas is determined, and each gas is input into one of the mixing tanks 9 for mixing; the helium solution configuration area 2 includes a helium gas tank 201 and a simulated water tank 202. A certain amount of helium gas is input into the helium gas tank 201 and a certain amount of simulated water is input into the simulated water tank 202, so as to obtain the simulated water and helium gas required for a certain concentration of helium solution. Three groups of helium solution configuration areas 2 are set, and high, medium, and low concentration helium solution conditions are respectively simulated with reference to the helium gas concentration in the formation water converted according to the cumulative helium production of the formation; four mixing tanks 9 are provided, one of which is filled with natural gas, and the rest are filled with low, medium, and high concentration helium solutions respectively.

[0025] The prepared helium solution and natural gas are delivered to the chamber below the piston 14 for testing. The pressing force of the pressing device (the pressing device can be a hydraulic telescopic rod, not shown in the figure) on the piston 14 can change with the pressure of the chamber, so as to maintain the stability of the chamber pressure. When it is time for sampling, the pipeline connected to the air outlet hole 21 of the lower chamber is opened, and the gas enters the gas component detection device 22 for detection to obtain the amount of helium in the natural gas layer after extracting helium, and then calculate the proportion of dissolved helium gas extracted. Among them, the gas component detection device 22 can be replaced by a steel cylinder, and the steel cylinder is collected and sent to an authoritative testing agency for testing.

[0026] The bottom of the test cylinder 17 is connected to a gas-liquid separator 15 through a pipeline. A first flowmeter 11 is provided on the pipeline connecting the test cylinder 17 and the gas-liquid separator 15. Both the bottom and the top of the gas-liquid separator 15 are connected to the gas component detection device 22 through pipelines. The helium solution is discharged from the bottom of the test cylinder 17, and the volume of the helium solution is obtained by the first flowmeter 11. The discharged helium solution enters the gas-liquid separator 15. The gas component detection device 22 estimates the concentration of helium in the helium solution in the test cylinder 17 based on the gas separated by the gas-liquid separator 15 and the residual helium concentration in the helium solution. By comparing the amount of dissolved and free helium gas in the gas layer in the test cylinder 17 with the total input amount of helium gas, the extraction amount of natural gas from the helium solution at different times is evaluated, and then the extraction effect intensity of natural gas on helium and the change law of its extraction rate are determined, which helps to reveal the enrichment mechanism of helium in natural gas. Knowing the content of helium in natural gas and the content of helium in the water discharged from the bottom of the test cylinder 17, the extraction effect intensity and rate of natural gas on dissolved helium can be quantitatively identified.

[0027] A protective cylinder 18 is sleeved outside the test cylinder 17. The dispensing tank 4 and the protective cylinder 18 are filled with a liquid heat-conducting medium (clean water or oil). Heating tubes 10 are provided in the dispensing tank 4 and the protective cylinder 18. Thermometers 8 for monitoring the temperature of the liquid heat-conducting medium are provided on the dispensing tank 4 and the protective cylinder 18. The heat generated by the heating tubes 10 is transferred to the dispensing tank 9 and the test cylinder 17 through the liquid heat-conducting medium to simulate the real formation temperature. By the change of the temperature value displayed by the thermometer 8, the opening and closing of the heating tubes 10 can be selectively controlled to maintain the temperature stability.

[0028] Heat-insulating layers are provided outside the dispensing tank 4 and the protective cylinder 18. The heat-insulating layers can reduce the temperature loss of the dispensing tank 4 and the protective cylinder 18, thereby reducing the opening and closing frequency of the heating tubes 10.

[0029] An exhaust pipe 6 is provided at the top of the dispensing tank 9. A valve is configured on the exhaust pipe 6 to discharge the residual gas in it before the experiment to avoid the influence of the residual gas on the test.

[0030] A first pressure gauge 7 is connected to the top of the blending tank 9 to check whether the pressure in the blending tank 9 is close to the formation pressure.

[0031] A second pressure gauge 13 and a second flowmeter 16 are provided on the pipeline connected to the air outlet 21. The second pressure gauge 13 can monitor the chamber pressure below the piston 14, thereby adjusting the pressing force of the pressing device accordingly; the second flowmeter 16 records the gas volume delivered to the gas component detection device 22 under the formation temperature and pressure conditions.

[0032] An observation window 5 is provided at the top of the blending box 4, and a transparent glass is provided at the top of the blending tank 9. The situation in the blending tank 9 can be observed through the observation window 5 and the transparent glass, so as to know whether the helium gas in the blending tank 9 is completely dissolved, minimizing heat loss to the greatest extent. If it does not dissolve quickly, it needs to stand for a period of time until the helium gas is completely dissolved before the test operation can be carried out. Among them, the transparent glass is tempered glass, which can ensure that the structural strength of the blending tank 9 meets the pressurization requirements. The transparent glass can also be provided on the exhaust pipe 6.

[0033] An output pipe is connected to each of the helium gas tank 201, the simulated water tank 202, and each gas tank 101, and a valve is provided on the output pipe to control the gas or liquid output of each tank body. The output pipes of all the gas tanks 101 converge into a main pipe and then communicate with the bottom of the blending tank 9. A compressor 3 and a valve are provided on the main pipe, and the valve is located between the compressor 3 and the blending tank 9; the output pipes of each group of helium gas tank 201 and simulated water tank 202 converge into a main pipe and then communicate with the bottom of the blending tank 9. A compressor 3 and a valve are also provided on the main pipe, and the valve is located between the compressor 3 and the blending tank 9; the compressor 3 pressurizes and conveys the corresponding gas or liquid into the blending tank 9 to increase the pressure in the blending tank 9.

[0034] Another branch discharge pipe is connected to the bottom of the blending tank 9, and valves are provided on each branch discharge pipe to control the gas or liquid discharge of each blending tank 9. All the branch discharge pipes converge into a main discharge pipe and then communicate with the air inlet 20. A compressor 3 is provided on the main discharge pipe to pressurize and convey to the chamber below the piston 14. When adjusting the chamber pressure, the rate of the compressor 3 can also be adjusted to cooperate with the pressing device for use. Among them, the main discharge pipe can be a flexible pipe or a rigid pipe; when using a flexible pipe, it is fixed on the piston 14 and can move with the piston 14; when using a rigid pipe, it is movably and hermetically inserted into the air inlet 20 and the air outlet 21.

[0035] A valve is provided on the pipeline connected to the air outlet 21, and this valve is located between the second pressure gauge 13 and the gas component detection device 22, and the second flowmeter 16 is located between the second pressure gauge 13 and the valve; valves are provided on the pipelines connected to the bottom of the test cylinder 17 and the bottom of the gas-liquid separator 15.

[0036] The above compressor 3 is a gas-liquid dual-purpose booster; the above valve is used to control the opening and closing of the corresponding pipeline, so as to realize the transportation and storage of gas or liquid.

[0037] The piston 14 is made of alloy casting, which has high strength, good heat conduction, and can withstand the temperature and pressure conditions of the simulated formation temperature and pressure state; a plurality of airtight rings are sleeved on the outer wall of the piston 14, which can ensure the airtightness between the piston 14 and the test cylinder 17. A stress pad 12 made of alloy casting is arranged on the piston 14. The stress pad 12 has high strength. When the stress pad 12 abuts against the pressing device, it can disperse the pressure of the mechanical pressure of the upper pressing device on the piston 14 and slow down the heat dissipation. A support frame 19 is arranged between the test cylinder 17 and the protection cylinder 18, so as to improve the structural strength of the test cylinder 17. The support frame 19 is in a hollow state, which helps the internal heating fluid to be heated evenly.

[0038] A method for evaluating the extraction ability of a natural gas layer for water-soluble helium gas, using an evaluation device, the evaluation method includes: According to the component identification results of the helium-containing natural gas, the simulated formation temperature and pressure, and the volume of the mixing tank 9, calculate the total volume of the simulated gas and the gas volumes of the main gas components according to the ideal gas state equation (see formula 1); pV=nRT (1) Wherein, p is the pressure (Pa), V is the gas volume (m³), T is the temperature (K), n is the amount of substance of the gas (mol), and R is the molar gas constant (J / (mol·K)); Inject various gas components of the natural gas into the evacuated gas tank 101 by volume, and sequentially transport each gas to one of the evacuated mixing tanks 9. After the transportation is completed, keep the mixing tank 9 in a closed state; According to the variation values of the solubility of helium in pure water with temperature and pressure (see Table 1), estimate the upper limit of the solubility of helium in formation water. Then, combined with the tectonic position of the formation, estimate the historical helium generation amount of the possible deep helium source rocks according to the historical helium generation amount calculation formula (see Formula 2-4). Combine the rock porosity and water content to estimate the dissolved helium concentration in the formation water, and take it as the low concentration value of the helium solution. Combine the volume of the mixing tank 9, and inject the corresponding amounts of helium and simulated water with the salinity of simulated formation water into the helium gas tank 201 and the simulated water tank 202 respectively. First, inject the simulated water into the mixing tank 9, and then inject helium to obtain a low concentration helium solution; on the basis of the low concentration helium solution, combined with the helium abundance in the gas reservoir and the amount of natural gas in the mixing tank 9, calculate the amount of helium gas to be injected for the medium concentration helium solution, inject the helium gas into the helium gas tank 201 in another set of helium solution preparation area 2, and then inject the simulated water and helium gas into another mixing tank 9; for the high concentration helium solution, consider the loss of helium gas in the geological history period, and take the value as twice the concentration of the medium concentration helium solution, and then inject the simulated water and helium gas into the remaining mixing tank 9; ρ n He =1.21×10 -13 ×U + 2.89×10 -14 ×Th (2) ρ n He is the 4 He generation intensity of the nth set of formations, with the unit of m 3 / t·a; U is the average abundance of uranium element in the nth set of formations, with the unit of ppm; Th is the average abundance of thorium element in the nth set of sedimentary formations, with the unit of ppm; Q n He = ρ n He × v n rock × ρ n s × T n rock (3) Q n He is the 4 historical cumulative helium generation amount of the nth set of formations, with the unit of m 3 ; ρ n He is the helium generation intensity of the rocks in the nth set of formations, with the unit of m 3 / t;v n rock is the volume of the nth formation, with the unit of m 3 ; ρ n s is the density of the rock in the nth formation, with the unit of m 3 / t; T n rock is the helium generation time of the nth formation, with the unit of a; The large release of helium gas generated by helium - generating elements in helium - bearing minerals requires a temperature higher than its closure temperature. There are obvious differences in the closure temperatures of different helium - bearing minerals. For example, the closure temperatures of apatite, hematite, zircon, garnet, monazite, sphene, and uraninite are 55 - 100 °C, 90 - 250 °C, 180 - 200 °C, 590 - 630 °C, 182 - 299 °C, 150 - 200 °C, and ~200 °C respectively. T n rock The value of can refer to the thermal history curve of the drill well to approximately estimate the time when its closure temperature is reached. In shale, U and Th mainly exist in adsorbed or complexed states, and there is no closure temperature for helium gas. The shale age can be approximately used as the T n rock value; Q He = Q 1 He + Q 2 He ……+ Q i He ……+ Q n He (4) Q He is the historical cumulative helium generation amount, with the unit of m 3 ; Q 1 He is the 4 historical cumulative helium generation amount of the first formation, with the unit of m 3 ; Q i He is the 4 historical cumulative helium generation amount of the ith formation, with the unit of m 3 ; Q n He is the 4 historical cumulative helium generation amount of the nth formation, with the unit of m 3 ; After all the dispensing tanks 9 are filled with the corresponding liquids and gases, turn on the heating tube 10 of the dispensing box 4, and raise the temperature of the dispensing box 4 to the formation temperature condition by heating in a water bath. When the helium gas in the dispensing tank 9 is completely dissolved, the test on the extraction ability of natural gas for helium in aqueous solution is carried out; Before the test, evacuate the chamber below the piston 14, preheat the temperature of the piston 14 to the simulated temperature through the heating tube 10, then inject high, medium, and low concentration helium solutions into the chamber in sequence, and finally add natural gas; the second pressure gauge 13 monitors the pressure change in the chamber, and then control the pressing device to keep the pressure in the chamber stable at the set simulated pressure value during the whole gas injection process. After standing for the designed sampling time, send the collected gas sample to the gas component detection device 22 (the gas component detection device 22 is a prior art) through the pipeline connected to the air outlet 21, and record the volume of the gas under the formation temperature and pressure conditions through the second flowmeter 16; the gas component detection device 22 obtains the amount of helium in the natural gas layer after extracting helium, and then calculates the proportion of the extracted dissolved helium; at the same time, the helium solution is discharged from the bottom of the test cylinder 17, the volume of the helium solution is obtained by the first flowmeter 11, and the discharged helium solution enters the gas-liquid separator 15. The gas component detection device 22 estimates the helium concentration in the helium solution in the test cylinder 17 based on the gas separated from the gas-liquid separator 15 and the residual helium concentration in the helium solution, and compares the amount of dissolved helium and free helium in the gas layer in the test cylinder 17 with the total input helium amount to evaluate the extraction amount of natural gas for the helium solution at different times, and then determine the extraction action intensity of natural gas for helium and the change law of its extraction rate.

[0039] Table 1 Variation values of helium solubility in pure water with temperature and pressure (ml / kg)

[0040] The present invention realizes the comprehensive simulation of complex geological conditions such as formation temperature, pressure, salinity, and water content in the laboratory environment, can set sampling at any time interval, quantitatively evaluate the extraction ability and rate of natural gas for helium in aqueous solution, and make up for the previous ideal state calculation based only on Henry's law or single-factor condition simulation, resulting in the inability to quantitatively evaluate the extraction ability of natural gas for aqueous helium and its contribution to the origin of helium in the natural gas layer. The present invention reveals the enrichment mechanism of helium in natural gas and directly serves the prediction of favorable areas for helium-rich natural gas.

[0041] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An evaluation device for the extraction ability of a natural gas layer to water-soluble helium gas, characterized in that It includes a natural gas configuration area (1), a helium solution configuration area (2), a dispensing tank (4), and a test cylinder (17). At least two dispensing tanks (9) are arranged in the dispensing tank (4). One of the dispensing tanks (9) is communicated with the natural gas configuration area (1), and the other dispensing tanks (9) are communicated with the helium solution configuration area (2). A piston (14) is movably and sealingly arranged in the test cylinder (17). An air inlet hole (20) and an air outlet hole (21) communicating with the inside of the piston (14) are formed in the piston (14). The air inlet hole (20) is communicated with the bottom of the dispensing tank (9) through a pipeline, and the air outlet hole (21) is connected with a gas component detection device (22) through a pipeline. The piston (14) is connected with a pressing device.

2. The evaluation device for the extraction ability of water-soluble helium gas by a natural gas layer according to claim 1, wherein The bottom of the test cylinder (17) is communicated with a gas-liquid separator (15) through a pipeline. A first flowmeter (11) is arranged on the pipeline connecting the test cylinder (17) and the gas-liquid separator (15). The bottom and the top of the gas-liquid separator (15) are both connected with the gas component detection device (22) through pipelines.

3. The evaluation device for the extraction ability of water-soluble helium gas by a natural gas layer according to claim 1, characterized in that, A protection cylinder (18) is sleeved outside the test cylinder (17). A liquid heat-conducting medium is filled in the dispensing tank (4) and the protection cylinder (18). Heating pipes (10) are arranged in the dispensing tank (4) and the protection cylinder (18). Thermometers (8) for monitoring the temperature of the liquid heat-conducting medium are arranged on the dispensing tank (4) and the protection cylinder (18).

4. An evaluation device for the extraction ability of water-soluble helium gas by a natural gas layer according to claim 3, characterized in that, A heat-insulating layer is arranged outside the dispensing tank (4) and the protection cylinder (18).

5. An apparatus for evaluating the extraction ability of a natural gas layer for water-soluble helium gas according to claim 1, characterized in that, An exhaust pipe (6) is arranged at the top of the dispensing tank (9).

6. The evaluation device for the extraction ability of water-soluble helium gas by a natural gas layer according to claim 1, characterized in that, A first pressure gauge (7) is connected to the top of the dispensing tank (9).

7. An apparatus for evaluating the extraction ability of a natural gas layer for water-soluble helium gas according to claim 1, characterized in that, A second pressure gauge (13) and a second flowmeter (16) are arranged on the pipeline connected to the air outlet hole (21).

8. An apparatus for evaluating the extraction ability of a natural gas layer for water-soluble helium gas according to claim 1, characterized in that, An observation window (5) is arranged at the top of the dispensing tank (4), and a transparent glass is arranged at the top of the dispensing tank (9).

9. An apparatus for evaluating the extraction ability of a natural gas layer for water-soluble helium gas according to claim 1, characterized in that, The natural gas configuration area (1) includes several gas tanks (101). The helium solution configuration area (2) includes a helium gas tank (201) and a simulated water tank (202). There are three groups in the helium solution configuration area (2) and are used for configuring helium gas and simulated water required for low, medium, and high concentration helium solutions. Four dispensing tanks (9) are arranged.

10. A method for evaluating the extraction ability of a natural gas layer for water-soluble helium, characterized in that, Using the evaluation device according to any one of claims 1-9, the evaluation method includes: Inject various gas components of natural gas into the evacuated gas tank (101) by volume, and sequentially transport each gas to one of the evacuated dispensing tanks (9); According to the variation values of the solubility of helium in pure water with temperature and pressure, estimate the upper limit of the solubility of helium in formation water. Then, combined with the tectonic position of the formation, estimate the historical helium generation amount of the possible deep helium source rocks according to the historical helium generation amount calculation formula. Combine the rock porosity and water content to estimate the dissolved helium concentration in the formation water, and use it as the low concentration value of the helium solution. Combine the volume of the blending tank (9), and inject corresponding amounts of helium and simulated water with the salinity of simulated formation water into the helium gas tank (201) and the simulated water tank (202) respectively. First, inject the simulated water into the blending tank (9), and then inject helium to obtain a low concentration helium solution; on the basis of the low concentration helium solution, combined with the helium abundance in the gas reservoir and the amount of natural gas in the blending tank (9), calculate the amount of helium gas to be injected for the medium concentration helium solution, inject the helium gas into the helium gas tank (201) in another helium solution preparation area (2), and then inject the simulated water and helium gas into another blending tank (9); for the high concentration helium solution, consider the loss of helium gas in the geological history period, and take the value as twice the concentration of the medium concentration helium solution, and then inject the simulated water and helium gas into the remaining blending tank (9). After all the blending tanks (9) are injected with the corresponding liquids and gases, turn on the heating tube (10) of the blending box (4), and raise the temperature of the blending box (4) to the formation temperature condition by heating in a water bath. When the helium gas in the blending tank (9) is completely dissolved, then conduct the test on the extraction ability of natural gas for dissolved helium gas. Before the test, evacuate the chamber below the piston (14), preheat the temperature of the piston (14) to the simulated temperature through the heating tube (10), then inject high, medium, and low concentration helium solutions into the chamber in sequence, and finally add natural gas; the second pressure gauge (13) monitors the pressure change in the chamber, and then control the pressing device to keep the pressure in the chamber stable at the set simulated pressure value during the entire gas injection process by pressing the piston (14). After standing until the designed sampling time, send the collected gas sample to the gas component detection device (22) through the pipeline connected to the air outlet (21), and record the volume of the gas under the formation temperature and pressure conditions through the second flowmeter (16); the gas component detection device (22) obtains the amount of helium gas in the gas reservoir after extracting helium gas, and then calculates the proportion of the extracted dissolved helium gas; at the same time, the helium solution is discharged from the bottom of the test cylinder (17), the volume of the helium solution is obtained by the first flowmeter (11), and the discharged helium solution enters the gas-liquid separator (15). The gas component detection device (22) estimates the helium concentration in the helium solution in the test cylinder (17) based on the gas separated by the gas-liquid separator (15) and the residual helium concentration in the helium solution. Compare the amount of dissolved helium gas and free helium gas in the gas reservoir in the test cylinder (17) with the total input amount of helium gas to evaluate the extraction amount of natural gas for the helium solution at different times, and then determine the extraction effect intensity of natural gas on helium gas and the variation law of its extraction rate.

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