Negative pressure gas sample sampler and negative pressure sampling method

Abstract

The present invention relates to a negative-pressure gas sample sampler and a negative-pressure sampling method. The negative-pressure gas sample sampler includes a desorption tank capable of being sealed and a sampling bottle. The desorption tank is used for desorbing shale gas from core samples. The bottom of the sampling bottle is arranged higher than the top of the desorption tank. The top of the desorption tank is connected to the top of the sampling bottle in a switchable manner. A negative-pressure generating structure is connected to the side wall of the sampling bottle in a switchable manner. The negative-pressure generating structure is used to reduce the pressure inside the sampling bottle to form a negative-pressure environment so as to suck the shale gas in the desorption tank. The present invention realizes negative-pressure sampling, ensures the continuity of shale gas desorption, improves the sealing performance while improving the sampling accuracy, and is convenient to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas production technology, and particularly relates to a negative pressure gas sample sampler and a negative pressure sampling method for shale gas desorption on site. Background Art

[0002] China is rich in shale gas resources, and the total geological resources of shale gas are 134.42×10 12 m 3 . In recent years, the exploration and development technology of shale gas in China has become increasingly mature. Gas content and gas components are important parameters for shale gas evaluation. At present, the desorption method is often used to measure the shale gas content, that is, the core obtained on site is loaded into a sealed desorption tank, and a metering device is used to directly measure the desorbed gas volume. During the desorption process, the drainage method is used to collect gas samples for gas component determination to determine the proportion of methane in the desorbed gas. However, due to the relatively small actual shale gas desorption pressure, it is often difficult to collect gas samples. Currently, the commonly used method on the desorption site is to seal the desorption tank and then sample after the shale gas has desorbed for a period of time. However, shale gas adsorption and desorption are reversible reactions, and "holding the breath" leads to discontinuous desorption, and manual sampling is likely to cause other gases such as air to mix in, resulting in errors in the test results. Therefore, designing and developing a negative pressure gas sample sampler is of great significance for accurately determining the gas components of shale gas.

[0003] There are numerous patents related to shale gas sample sampling devices, and the sampling bottles are constantly being improved. Patent CN201811324434, "A Membrane Sealed Shale Gas Sealed Sampling Device", solves the problem that the existing sampling equipment for shale gas has poor sealing performance during the sampling process and cannot achieve a completely sealed effect. However, its application environment is to collect shale gas samples in soil, and the gas pressure is much higher than the on-site desorbed gas. Patent CN201810946093, "A Shale Gas Sealed Sampling Device", sets up a bottle fixing device that can fix the sampling bottle to avoid leakage caused by the impact of the sampling bottle and the box body during movement. However, during its sampling process, an air pump needs to be used to make the shale gas enter the sampling bottle, and the operation is relatively complicated.

[0004] Therefore, based on the experience and practice of being engaged in the relevant industry for many years, the inventor of the present invention proposes a negative pressure gas sample sampler and a negative pressure sampling method to overcome the defects of the existing technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a negative pressure gas sample sampler and a negative pressure sampling method to overcome the problems existing in the existing technology. The present invention realizes negative pressure sampling, ensures the continuity of shale gas desorption, improves the sealing performance while improving the sampling accuracy, and is convenient to operate.

[0006] The object of the present invention is achieved in this way. A negative pressure gas sample sampler includes a sealable desorption tank and a sampling bottle. The desorption tank is used for desorbing shale gas from core samples. The bottom of the sampling bottle is arranged higher than the top of the desorption tank. The top of the desorption tank is connected to the top of the sampling bottle in a switchable manner. A negative pressure generating structure is connected to the side wall of the sampling bottle in a switchable manner. The negative pressure generating structure is used to reduce the pressure inside the sampling bottle to form a negative pressure environment for sucking the shale gas in the desorption tank.

[0007] In a preferred embodiment of the present invention, the negative pressure generating structure includes a liftable water tank structure. Water is contained in the water tank structure. The bottom of the water tank structure is connected to the side wall of the sampling bottle through a first conduit in a switchable manner. The water tank structure can rise to inject water into the sampling bottle, and the water tank structure can descend to form a negative pressure environment inside the sampling bottle.

[0008] In a preferred embodiment of the present invention, a switchable first quick connector is arranged on the side wall of the sampling bottle. A switchable second quick connector is arranged at the first end of the first conduit. The second quick connector can be buckled and communicated with the first quick connector. The second end of the first conduit is communicated with the bottom of the water tank structure.

[0009] In a preferred embodiment of the present invention, the first quick connector is arranged in the middle of the side wall of the sampling bottle.

[0010] In a preferred embodiment of the present invention, the top of the desorption tank is connected to the first end of a second conduit. A switchable third quick connector is arranged at the second end of the second conduit. A switchable fourth quick connector is arranged at the top of the sampling bottle. The third quick connector can be buckled and communicated with the fourth quick connector.

[0011] In a preferred embodiment of the present invention, a lifting rod is connected to the water tank structure.

[0012] In a preferred embodiment of the present invention, the desorption tank is arranged in a constant temperature water bath.

[0013] In a preferred embodiment of the present invention, a scale unit is arranged on the side wall of the sampling bottle.

[0014] In a preferred embodiment of the present invention, the sampling bottle is a transparent glass bottle.

[0015] The object of the present invention can also be achieved in this way. A negative pressure sampling method includes the following steps:

[0016] Step a: Prepare the negative pressure gas sample sampler as described above;

[0017] Step b: After filling the desorption tank with core samples, seal it and place it in a constant temperature water bath. Disconnect the desorption tank from the sampling bottle and the water tank structure from the sampling bottle. Raise the water tank structure until the bottom of the water tank structure is higher than the top of the sampling bottle and then stop. Connect the water tank structure to the sampling bottle. After the sampling bottle is filled with water, disconnect the water tank structure from the sampling bottle. Lower the water tank structure until the top of the water tank structure is lower than the bottom of the sampling bottle and then stop, preparing for the generation of a negative pressure environment.

[0018] Step c: Connect the desorption tank to the sampling bottle and at the same time connect the water tank structure to the sampling bottle. The water in the sampling bottle flows into the water tank structure, creating a negative pressure environment in the sampling bottle. The shale gas desorbed from the core samples in the desorption tank enters the sampling bottle.

[0019] Step d: When the gas volume in the sampling bottle meets the sampling requirements, disconnect the water tank structure from the sampling bottle and the desorption tank from the sampling bottle. Remove the sampling bottle, attach a numbered label, and invert it for packing. Drain the remaining shale gas in the desorption tank.

[0020] Step e: Replace the core samples in the desorption tank, reconfigure the sampling bottle, and repeat steps b, c, and d for the next round of sampling.

[0021] As described above, the negative pressure gas sampling device and the negative pressure sampling method provided by the present invention have the following beneficial effects:

[0022] In the negative pressure gas sampling device provided by the present invention, the negative pressure generating structure reduces the pressure in the sampling bottle to form a negative pressure environment, solving the problem of difficult sampling caused by the small pressure of the shale gas desorbed from the core samples, realizing negative pressure sampling. The shale gas in the desorption tank can continuously enter the sampling bottle under the action of negative pressure, avoiding the "stuffy gas" sampling of shale gas at the current shale gas desorption site and ensuring the continuity of shale gas desorption. The negative pressure generating structure makes full use of the U-shaped tube principle, with a simple structure. By simple operation, a negative pressure environment can be formed in the sampling bottle to realize the suction of shale gas in the desorption tank. The connection between the desorption tank and the sampling bottle, and between the sampling bottle and the negative pressure generating structure uses quick connectors, solving the problem of poor sealing of traditional sampling bottles using rubber stoppers, improving the sealing performance and sampling accuracy while making the operation more convenient. The negative pressure gas sampling device and the negative pressure sampling method provided by the present invention can realize sampling and control by controlling the on-off of the desorption tank, the sampling bottle, and the negative pressure generating structure, solving the difficulty of manual drainage sampling during the traditional on-site desorption process and making the operation more convenient. Description of the Drawings

[0023] The following drawings are only intended to illustrate and explain the present invention and do not limit the scope of the present invention. Among them:

[0024] Figure 1 : Schematic diagram of the negative pressure gas sampling device of the present invention.

[0025] In the figure:

[0026] 100, Negative pressure gas sample sampler; 1, Constant temperature water bath; 2, Core sample; 3, Desorption tank; 4, Second conduit; 5, Second quick connector; 6, First quick connector; 7, Third quick connector; 8, Fourth quick connector; 9, Sampling bottle; 10, Negative pressure generating structure; 11, Lifting rod; 12, First conduit. Detailed implementation manners

[0027] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation manners of the present invention will now be described with reference to the accompanying drawings.

[0028] The specific implementation manners of the present invention described herein are only for the purpose of explaining the objectives of the present invention and should not be construed in any way as a limitation of the present invention. Under the teachings of the present invention, those skilled in the art can conceive of any possible variations based on the present invention, and all of these should be regarded as falling within the scope of the present invention. It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the communication inside two elements. It can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation manner.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific implementation manners and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0030] As Figure 1As shown in the figure, the present invention provides a negative-pressure gas sample sampler 100, which includes a sealable desorption tank 3 and a sampling bottle 9. The desorption tank 3 is used for desorbing shale gas from the core sample 2. The bottom of the sampling bottle 9 is arranged higher than the top of the desorption tank 3. The top of the desorption tank 3 is connected to the top of the sampling bottle 9 in a switchable manner (connecting the top of the desorption tank 3 and the top of the sampling bottle 9 according to the sampling requirement, or disconnecting the connection between the two). A negative-pressure generating structure 10 is connected to the side wall of the sampling bottle 9 in a switchable manner (connecting the negative-pressure generating structure 10 and the sampling bottle 9 according to the sampling requirement, or disconnecting the connection between the two). The negative-pressure generating structure 10 is used to reduce the pressure in the sampling bottle 9 to form a negative-pressure environment so as to suck the shale gas in the desorption tank 3.

[0031] Currently, the drainage method is mostly used to collect gas samples. A sampling glass bottle is used to collect the gas generated in the desorption tank in a water bath. The existing sampling glass bottle is sealed with a rubber stopper, and the sealing performance is poor. Moreover, the sampling glass bottle usually needs to be transported back to the laboratory for testing from the field. During transportation, bumps are likely to cause the rubber stopper to fall off, resulting in sampling failure. At the same time, the manual drainage method is also likely to cause the collected gas sample to be impure. For example, if the air in the bottle is not completely exhausted during the process of filling the sampling glass bottle with water, it will lead to gas test errors.

[0032] In the negative-pressure gas sample sampler provided by the present invention, the negative-pressure generating structure reduces the pressure in the sampling bottle to form a negative-pressure environment, solves the problem of difficult sampling caused by the small pressure of desorbing shale gas from the core sample, realizes negative-pressure sampling, and the shale gas in the desorption tank can continuously enter the sampling bottle under the action of negative pressure, avoiding the "stuffy gas" sampling of shale gas at the current shale gas desorption site, and ensuring the continuity of shale gas desorption; the negative-pressure gas sample sampler provided by the present invention can realize sampling and control by controlling the on-off of the desorption tank, the sampling bottle and the negative-pressure generating structure, solves the difficulty of manual drainage sampling in the traditional on-site desorption process, and the operation is more convenient.

[0033] Further, as Figure 1 shown, the negative-pressure generating structure 10 includes a water tank structure that can be lifted. The water tank structure contains water, and the bottom of the water tank structure is connected to the side wall of the sampling bottle 9 through a first conduit 12 in a switchable manner; the water tank structure can rise to inject water into the sampling bottle 9, and the water tank structure can descend to form a negative-pressure environment in the sampling bottle 9. The negative-pressure generating structure 10 makes full use of the U-tube principle, has a simple structure, and can form a negative-pressure environment in the sampling bottle 9 with simple operation to realize the suction of the shale gas in the desorption tank 3.

[0034] Further, as Figure 1As shown in the figure, a first quick connector 6 that can be opened and closed is provided on the side wall of the sampling bottle 9. A second quick connector 5 that can be opened and closed is provided at the first end of the first conduit 12. The second quick connector 5 can be snap-fitted and communicated with the first quick connector 6. The second end of the first conduit 12 is communicated with the bottom of the water tank structure. Both the first quick connector 6 and the second quick connector 5 are quick connectors. In the separated state, their openings are both closed and in a non-air-conducting state; when the first quick connector 6 and the second quick connector 5 are inserted and combined, they are in an air-conducting state after being communicated.

[0035] In this embodiment, the first quick connector 6 is provided in the middle of the side wall of the sampling bottle 9. That is, the first quick connector 6 is at a distance of 1 / 2 of the bottle height from the bottom of the sampling bottle 9. The first quick connector 6 is provided with an opening in the middle. This structural design can keep the sampling bottle 9 always in a hydraulically closed state for the gas, which is beneficial to the movement and preservation of the gas sample.

[0036] Further, as Figure 1 shown, the top of the desorption tank 3 is connected to the first end of the second conduit 4. A third quick connector 7 that can be opened and closed is provided at the second end of the second conduit 4. A fourth quick connector 8 that can be opened and closed is provided at the top of the sampling bottle 9. The third quick connector 7 can be snap-fitted and communicated with the fourth quick connector 8.

[0037] Both the third quick connector 7 and the fourth quick connector 8 are quick connectors. In the separated state, their openings are both closed and in a non-air-conducting state; when the third quick connector 7 and the fourth quick connector 8 are inserted and combined, they are in an air-conducting state after being communicated.

[0038] The connection between the desorption tank 3 and the sampling bottle 9, and between the sampling bottle 9 and the negative pressure generating structure 10 (water tank structure) uses quick connectors, which solves the problem of poor sealing of traditional sampling bottles using rubber stoppers, improves the sealing performance while improving the sampling accuracy, and is convenient to operate.

[0039] Further, as Figure 1 shown, a lifting rod 11 is connected to the water tank structure, and the lifting of the water tank structure is realized through the lifting rod 11.

[0040] Further, as Figure 1 shown, the desorption tank 3 is arranged in the constant temperature water bath box 1.

[0041] In this embodiment, the desorption tank 3 is a cylindrical container with a diameter of 20 cm and a height of 40 cm, used to hold the core sample 2 of the shale taken from the site. It is heat-resistant and has good airtightness. The core sample 2 usually fills the entire desorption tank 3. In case of insufficient sampling amount, steel balls or the like need to be placed in the desorption tank 3 to reduce the volume of air in the tank. During the actual desorption process, the desorption tank 3 needs to be placed in a constant temperature water bath 1 (a box for heating water, but it can maintain a constant temperature, with a temperature difference of about ±1 °C). The water submerges the desorption tank 3, and the desorption test is carried out under the actual underground temperature conditions. The desorption temperature is mostly above 50 °C, and in some areas, due to the relatively high depth of the shale, the temperature can reach 90 °C.

[0042] Furthermore, a scale unit is provided on the side wall of the sampling bottle 9, which can accurately control the volume of the sampled shale gas and improve the sampling accuracy.

[0043] In this embodiment, the sampling bottle 9 is a transparent glass bottle, which is convenient for observing the rise and fall of the water level in the bottle and can accurately control the sampling volume.

[0044] The present invention also provides a negative pressure sampling method, which includes the following steps:

[0045] Step a: Prepare the negative pressure gas sample sampler 100 described above;

[0046] Step b: After filling the core sample 2 into the desorption tank 3, seal it and place it in the constant temperature water bath 1. Disconnect the desorption tank 3 from the sampling bottle 9 (disconnect the third quick connector 7 and the fourth quick connector 8), and disconnect the water tank structure from the sampling bottle 9 (disconnect the first quick connector 6 and the second quick connector 5); Stop when the bottom of the rising water tank structure is higher than the top of the sampling bottle 9, and connect the water tank structure to the sampling bottle 9 (insert and connect the first quick connector 6 and the second quick connector 5). After the water fills the sampling bottle 9, disconnect the water tank structure from the sampling bottle 9 (disconnect the first quick connector 6 and the second quick connector 5); Stop when the top of the descending water tank structure is lower than the bottom of the sampling bottle 9 to prepare for generating a negative pressure environment;

[0047] Step c: Connect the desorption tank 3 to the sampling bottle 9 (insert and connect the third quick connector 7 and the fourth quick connector 8), and at the same time connect the water tank structure to the sampling bottle 9 (insert and connect the first quick connector 6 and the second quick connector 5). The water in the sampling bottle 9 flows into the water tank structure, a negative pressure environment is formed in the sampling bottle 9, and the shale gas desorbed from the core sample 2 in the desorption tank 3 enters the sampling bottle 9;

[0048] Step d: When the gas volume in the sampling bottle 9 meets the sampling requirements, disconnect the water tank structure from the sampling bottle 9, disconnect the desorption tank 3 from the sampling bottle 9, remove the sampling bottle 9, attach a numbered label, invert it and pack it in a box; Discharge the remaining shale gas in the desorption tank 3;

[0049] Specifically, the volume of the sampled gas can be confirmed according to the scale unit on the side wall of the sampling bottle 9. When the gas volume in the sampling bottle 9 meets the sampling requirements, the second quick connector 5 is unplugged from the first quick connector 6, and the third quick connector 7 is unplugged from the fourth quick connector 8. The first quick connector 6 and the fourth quick connector 8 return to the closed state, and the sampling bottle 9 is sealed.

[0050] Another fourth quick connector 8 is taken and inserted into the third quick connector 7 to connect the two, and the remaining shale gas in the desorption tank 3 is discharged.

[0051] Step e: Replace the core sample 2 in the desorption tank 3, reconfigure the sampling bottle 9, and repeat steps b, c, and d to perform the next round of sampling.

[0052] As described above, the negative pressure gas sample sampler and the negative pressure sampling method provided by the present invention have the following beneficial effects:

[0053] In the negative pressure gas sample sampler provided by the present invention, the negative pressure generating structure reduces the pressure in the sampling bottle to form a negative pressure environment, solves the problem of difficult sampling caused by the small pressure of the core sample desorbing shale gas, realizes negative pressure sampling, and the shale gas in the desorption tank can continuously enter the sampling bottle under the action of negative pressure, avoiding the "stuffy gas" sampling of shale gas at the current shale gas desorption site and ensuring the continuity of shale gas desorption; the negative pressure generating structure makes full use of the U-shaped tube principle, has a simple structure, and can form a negative pressure environment in the sampling bottle with simple operation to realize the suction of shale gas in the desorption tank; the connection between the desorption tank and the sampling bottle, and between the sampling bottle and the negative pressure generating structure uses quick connectors, which solves the problem of poor sealing of traditional sampling bottles using rubber stoppers, improves the sealing performance and sampling accuracy while making the operation more convenient; the negative pressure gas sample sampler and the negative pressure sampling method provided by the present invention can realize sampling and control by controlling the on-off of the desorption tank, the sampling bottle and the negative pressure generating structure, solve the difficulty of manual sampling by the drainage method in the traditional on-site desorption process, and make the operation more convenient.

[0054] The above description is only a schematic specific embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A negative pressure gas sample sampler, characterized in that, It includes a sealable desorption tank and a sampling bottle. The desorption tank is used for desorbing shale gas from core samples. The bottom of the sampling bottle is set higher than the top of the desorption tank. The top of the desorption tank is connected to the top of the sampling bottle in a switchable manner. A negative pressure generating structure is connected to the side wall of the sampling bottle in a switchable manner. The negative pressure generating structure is used to reduce the pressure inside the sampling bottle to form a negative pressure environment so as to suck the shale gas in the desorption tank. The negative pressure generating structure includes a liftable water tank structure. Water is contained in the water tank structure. The bottom of the water tank structure is connected to the side wall of the sampling bottle through a first conduit in a switchable manner. The water tank structure can rise to inject water into the sampling bottle, and the water tank structure can descend to form a negative pressure environment inside the sampling bottle.

2. The negative pressure gas sample sampler according to claim 1, wherein, A switchable first quick connector is provided on the side wall of the sampling bottle. A switchable second quick connector is provided at the first end of the first conduit. The second quick connector can be buckled and communicated with the first quick connector. The second end of the first conduit is communicated with the bottom of the water tank structure.

3. The negative pressure gas sample sampler according to claim 2, wherein, The first quick connector is provided in the middle of the side wall of the sampling bottle.

4. The negative pressure gas sample sampler according to claim 1, characterized in that, The top of the desorption tank is connected to the first end of a second conduit. A switchable third quick connector is provided at the second end of the second conduit. A switchable fourth quick connector is provided at the top of the sampling bottle. The third quick connector can be buckled and communicated with the fourth quick connector.

5. The negative pressure gas sample sampler according to claim 1, wherein, A lifting rod is connected to the water tank structure.

6. The negative pressure gas sample sampler according to claim 1, wherein The desorption tank is arranged in a constant temperature water bath.

7. The negative pressure gas sample sampler according to claim 1, characterized in that, A scale unit is provided on the side wall of the sampling bottle.

8. The negative pressure gas sample sampler according to claim 1, wherein, The sampling bottle is a transparent glass bottle.

9. A negative pressure sampling method, characterized in that, It includes the following steps: Step a: Prepare the negative pressure gas sample sampler according to any one of claims 1 to 8. Step b: After filling the core sample into the desorption tank, seal it and place it in the constant temperature water bath. Disconnect the desorption tank from the sampling bottle, and disconnect the water tank structure from the sampling bottle. Stop rising the water tank structure until its bottom is higher than the top of the sampling bottle. Connect the water tank structure and the sampling bottle. After the sampling bottle is filled with water, disconnect the water tank structure from the sampling bottle. Stop descending the water tank structure until its top is lower than the bottom of the sampling bottle to prepare for generating a negative pressure environment. Step c: Connect the desorption tank and the sampling bottle, and at the same time connect the water tank structure and the sampling bottle. The water in the sampling bottle flows into the water tank structure, a negative pressure environment is formed in the sampling bottle, and the shale gas desorbed from the core sample in the desorption tank enters the sampling bottle. Step d: When the gas volume in the sampling bottle meets the sampling requirements, disconnect the water tank structure from the sampling bottle, disconnect the desorption tank from the sampling bottle, remove the sampling bottle, attach a numbered label, invert it and pack it in a box. Drain the remaining shale gas in the desorption tank. Step e: Replace the core sample in the desorption tank, reconfigure the sampling bottle, and repeat steps b, c, and d to conduct the next round of sampling.

Images