Wellhead gas sampler

Abstract

The utility model belongs to the technical field of gas sampling devices, and particularly relates to a wellhead gas sampler which comprises a sampling cylinder with a cylinder side wall and a cylinder bottom wall, a fluid inlet is formed in the cylinder bottom wall, and a piston which is in sealing and sliding fit with the inner circumferential surface of the cylinder side wall is arranged in the sampling cylinder. The sliding stroke of the piston has an exhaust stroke for moving close to the fluid inlet to exhaust gas in the sampling cylinder and also has a sampling stroke for moving away from the fluid inlet to enable fluid to enter the sampling cylinder, a sampling hole penetrating through the inner circumferential surface and the outer circumferential surface of the cylinder side wall is formed in the cylinder side wall, and the sampling hole is a straight hole and is provided with an inner side orifice and an outer side orifice; the inner side orifice is communicated with the inner cavity of the sampling cylinder, the sampling stroke of the piston comprises a crossing station capable of crossing the inner side orifice, and the outer side orifice is directly or indirectly connected with a sampling valve. Therefore, the thickness of the side wall of the cylinder is reduced, the processing cost is reduced, and the processing difficulty is reduced as the exhaust section and the air inlet section of the inner cavity of the sampling cylinder do not need to be processed.

Description

Technical Field

[0001] The utility model relates to a wellhead gas sampler, belonging to the technical field of gas sampling devices. Background Art

[0002] Carbon dioxide flooding technology refers to the technology of using carbon dioxide as a flooding medium to improve crude oil recovery. During the carbon dioxide flooding process, gas channeling will occur due to the influence of the formation. The more serious the gas channeling is, the lower the recovery rate will be. Therefore, effectively identifying and inhibiting or delaying gas channeling is of great significance to carbon dioxide flooding.

[0003] In the prior art, a sampling tube is used to analyze the gas in the oil well output liquid to determine whether gas channeling occurs. The oil well output liquid is a mixture of gas phase and liquid phase. When sampling, the sampling valve at the top of the sampling tube is first opened, and then the sampling tube is connected to the oil well wellhead manifold, and the oil well output liquid in the manifold is passed into the sampling tube. The gas phase and liquid phase in the oil well output liquid are separated in the sampling tube. As the oil well output liquid is continuously passed in, the separated gas phase and liquid phase squeeze out the air in the sampling tube. After the air is completely discharged, the sampling bag is connected to the sampling valve to sample the gas phase. Although the above device can sample the gas phase in the oil well output liquid, there are problems such as the air in the sampling tube is not completely exhausted, resulting in low sampling purity, or the oil well output liquid is passed in for a long time in order to completely exhaust the air, resulting in a large amount of gas phase being discharged into the air through the sampling valve to pollute the environment.

[0004] Based on the above problems, a Chinese utility model patent with authorization announcement number CN217440014U discloses a gas sampling device at the wellhead of an oil and gas well, including a sampling cylinder with a piston cavity (i.e., an inner cavity), the piston cavity including a front cavity wall (i.e., a bottom wall of the cylinder) and a cavity side wall (i.e., a side wall of the cylinder), an exhaust piston (i.e., a piston) is installed in the piston cavity guide, an inlet valve for gas to enter is provided on the front cavity wall of the piston cavity, the front cavity wall is a concave conical cavity wall, the exhaust piston is a corresponding conical piston, which is used to empty the gas in the piston cavity when the two are in contact, and the rear of the sampling cylinder is provided with a conical cavity wall. A sealing cover is provided at the end, and a driving rod is passed through the sealing cover. The driving rod is connected to the exhaust piston to drive the exhaust piston to perform exhaust and pumping actions. An outlet channel (i.e., a sampling hole) is provided on the side wall of the piston cavity, including an exhaust section extending along the axial direction of the sampling cylinder and an air intake section connecting the exhaust section and the piston cavity. An exhaust valve (i.e., a sampling valve) is provided on the exhaust section of the outlet channel. The exhaust piston can move backward and pass over the air inlet of the air intake section under the drive of the driving rod, so that when the exhaust valve is opened, the gas in the oil and gas well passes through the air intake valve, the piston cavity and the outlet channel in sequence to fill the sampling cylinder.

[0005] If the above structure is used for sampling of oil well produced fluid, although the problem of residual air contamination in the sampling tube is solved and the sampling purity of the gas sample is improved, the sampling hole of the gas sampling device is set as an exhaust section extending along the axial direction of the sampling tube on the side wall of the tube and an air intake section connecting the exhaust section and the inner cavity of the sampling tube, and the exhaust valve is arranged in the exhaust section, so that the side wall of the sampling tube needs to have a certain thickness to open the air outlet channel and install the exhaust valve, which makes the material required for processing the sampling tube more, resulting in higher processing costs, and the air intake section needs to be processed in the piston cavity, and the overall processing difficulty is high. Utility Model Content

[0006] The utility model aims to provide a wellhead gas sampler to solve the problems of high processing cost and great processing difficulty caused by the existing gas sampling device that the sampling hole is arranged on the side wall of the tube, the exhaust section is extended along the axial direction of the sampling tube, and the air intake section connects the exhaust section and the inner cavity of the sampling tube, and the sampling valve is arranged in the exhaust section.

[0007] In order to achieve the above purpose, the wellhead gas sampler of the utility model adopts the following technical solutions:

[0008] A wellhead gas sampler comprises a sampling barrel having a barrel side wall and a barrel bottom wall, a fluid inlet being arranged on the barrel bottom wall, a piston being arranged in the sampling barrel and being sealed and slidably matched with the inner circumference of the barrel side wall, the piston having an exhaust stroke in the sliding stroke in which the piston moves close to the fluid inlet to exhaust the gas in the sampling barrel, and a sampling stroke in which the piston moves away from the fluid inlet to allow the fluid to enter the sampling barrel, a sampling hole penetrating the inner circumference and the outer circumference of the barrel side wall being arranged on the barrel side wall, the sampling hole being a straight hole and having an inner orifice and an outer orifice, the inner orifice being connected to the inner cavity of the sampling barrel, and the sampling stroke of the piston including a passing position capable of passing over the inner orifice, and a sampling valve being directly or indirectly connected to the outer orifice position.

[0009] Beneficial effects: The utility model belongs to an improved invention. By setting a sampling hole penetrating the inner and outer peripheral surfaces of the side wall of the tube on the side wall of the tube, the sampling hole is a straight hole with an inner orifice and an outer orifice, and the outer orifice is directly or indirectly connected to a sampling valve. Compared with the existing structure in which the sampling hole is set on the side wall of the sampling tube and extends along the axis to the top of the sampling tube, it is no longer necessary to make the sampling tube have a certain thickness to extend the exhaust section along the axial direction on the side wall of the sampling tube and install the sampling valve in the exhaust section, thereby reducing the thickness of the tube side wall of the sampling tube, thereby reducing the materials required for processing the sampling tube, reducing the processing cost, and at the same time, it is not necessary to process the exhaust section and the air intake section connecting the inner cavity of the sampling tube, but directly drilling a hole through the side wall of the tube on the outside of the sampling tube, thereby reducing the processing difficulty. The inner orifice is connected to the inner cavity of the sampling tube and the sampling stroke of the piston includes a crossing position that can cross the inner orifice, which ensures that the gas to be sampled can be discharged from the inner cavity of the sampling tube through the sampling hole, thereby ensuring the sampling of the gas at the sampling valve.

[0010] Furthermore: the sampling hole extends radially along the side wall of the cylinder.

[0011] Furthermore, the distance from the sampling hole to the end face of the tube mouth of the sampling tube is less than one third of the axial length of the tube side wall.

[0012] Furthermore: the sampling valve is connected with a hose for communicating with a sampling bag.

[0013] Furthermore: the wellhead gas sampler also includes a sealing cover connected to the mouth of the sampling barrel, the sealing cover includes a cover body and a flange, the flange is provided with an internal thread, the outer periphery of the mouth of the sampling barrel is provided with an external thread matching the internal thread, the wellhead gas sampler also includes a driving rod passing through the cover body and connected to the piston to drive the piston to slide in the sampling barrel, and the cover body is provided with a through hole for the driving rod to pass through.

[0014] Furthermore, bosses are respectively provided on the inner and outer surfaces of the cover body at the positions of the perforations.

[0015] Furthermore, the through hole is a light hole, and the gap between the driving rod and the light hole constitutes a gas gap for the piston to flow through the gas inside and outside the sampling cylinder during the exhaust stroke and the sampling stroke.

[0016] Furthermore: a tripod structure for supporting the sampling cylinder is arranged on the bottom wall of the cylinder.

[0017] Furthermore: a fluid control valve is installed at the fluid inlet, and the fluid control valve is located on the inner side of the tripod structure.

[0018] Furthermore: the ratio of the diameter and height of the sampling cylinder is 1:1.5~2. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of an embodiment of the wellhead gas sampler of the utility model.

[0020] In the figure: 1. sampling cylinder; 11. tripod structure; 2. sealing cap; 21. cover body; 211. perforation; 212. boss; 22. flange; 3. driving rod; 4. piston; 5. fluid inlet; 6. fluid control valve; 7. sampling hole; 8. sampling valve; 9. hose. DETAILED DESCRIPTION

[0021] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0022] In view of the technical problems existing in the prior art, the basic technical concept of the utility model is to provide a sampling hole on the side wall of the cylinder that penetrates the inner and outer peripheral surfaces of the side wall of the cylinder. The sampling hole is a straight hole and has an inner orifice and an outer orifice. The inner orifice is connected to the inner cavity of the sampling cylinder and the sampling stroke of the piston includes a crossing position that can cross the inner orifice. The outer orifice is directly or indirectly connected to a sampling valve. There is no need to make the sampling cylinder have a certain thickness to extend the exhaust section axially on the side wall of the sampling cylinder and install the sampling valve in the exhaust section, thereby reducing the thickness of the side wall of the sampling cylinder, thereby reducing the materials required for processing the sampling cylinder, reducing the processing cost, and at the same time, there is no need to process the exhaust section and the air intake section connecting the inner cavity of the sampling cylinder, but it is sufficient to drill a hole directly through the side wall of the cylinder on the outside of the sampling cylinder, thereby reducing the processing difficulty. The inner orifice is connected to the inner cavity of the sampling tube and the sampling stroke of the piston includes a crossing position that can cross the inner orifice, ensuring that the gas to be sampled can be discharged from the inner cavity of the sampling tube through the sampling hole, thereby ensuring the sampling of the gas at the sampling valve.

[0023] Based on the above concept, the embodiment of the wellhead gas sampler of the utility model is as follows:

[0024] like Figure 1As shown, the wellhead gas sampler includes a sampling tube 1 having a tube side wall and a tube bottom wall. The tube side wall and the tube bottom wall of the sampling tube 1 form an inner cavity of the sampling tube. A fluid inlet 5 is provided on the tube bottom wall. The fluid inlet 5 is connected to a fluid control valve 6. The tube side wall is provided with a sampling hole 7 that penetrates the inner circumference and the outer circumference of the tube side wall. The sampling hole 7 is a straight hole. Preferably, the sampling hole 7 extends along the radial direction of the tube side wall. When processing the sampling hole 7, drilling can be performed perpendicular to the direction of the tube side wall, which further reduces the processing difficulty of the sampling hole 7. The sampling hole 7 has an inner orifice and an outer orifice. The inner orifice is connected to the inner cavity of the sampling tube 1. The outer orifice is connected to a sampling valve 8, which is specifically a threaded connection. The sampling cylinder 1 is also provided with a piston 4 which is sealed with the inner circumferential surface of the cylinder side wall and can slideably cooperate with it. The sliding stroke of the piston 4 includes an exhaust stroke in which it moves close to the fluid inlet 5 to discharge the gas in the sampling cylinder 1, and a sampling stroke in which it moves away from the fluid inlet to allow the fluid to enter the sampling cylinder 1. The sampling stroke of the piston 4 also includes a crossing position that can cross the inner orifice, so that the gas in the inner cavity of the sampling cylinder 1 can be sampled through the sampling valve 8.

[0025] In this embodiment, the fluid to be sampled is specifically the oil well production fluid in the wellhead manifold of the oil well. The oil well production fluid overcomes the resistance at the fluid control valve 6 and pushes the piston 4 away from the bottom wall of the barrel to enter the sampling barrel 1. After entering the sampling barrel 1, the mixed gas and liquid phase in the oil well production fluid are separated. When the piston 4 slides to the sampling stroke, the separated gas is sampled at the sampling hole 7. In order to avoid the sampling hole 7 being set too low, causing the liquid phase in the oil well production fluid to overflow from the sampling hole 7 and interfere with the sampling, the distance from the sampling hole 7 to the barrel mouth end face of the sampling barrel 1 is less than one-third of the axial length of the barrel side wall. Specifically, the distance from the sampling hole 7 to the barrel mouth end face of the sampling barrel 1 is one-fifth of the axial length of the barrel side wall, which not only avoids the liquid phase in the oil well production fluid from overflowing from the sampling hole 7 to interfere with the sampling, but also avoids the excessive length of the sampling barrel 1 wall above the sampling hole 7, resulting in material waste. In order to facilitate the sampling operation and avoid the sampling container being difficult to connect to the sampling valve 8, which would result in low sampling efficiency, the sampling valve 8 is also connected to a hose 9 for connecting to a sampling bag.

[0026] The wellhead gas sampler also includes a sealing cover 2 connected to the mouth of the sampling tube 1, the sealing cover 2 includes a cover body 21 and a flange 22, the flange 22 is provided with an internal thread, the outer periphery of the mouth of the sampling tube 1 is provided with an external thread matched with the internal thread, the wellhead gas sampler also includes a driving rod 3 passing through the cover body 21 and connected to the piston 4 to drive the piston 4 to slide in the sampling tube 1, the cover body 21 is provided with a through hole 211 for the driving rod 3 to pass through, the setting of the sealing cover 2 protects the sampling tube 1 from environmental pollution, and the threaded connection method is simple to process and easy to connect. The driving rod 3 passing through the through hole 211 also improves the manipulation of the piston 4. When the pressure of the oil well output fluid is not enough to push the piston 4 away from the bottom wall of the tube, the driving rod 3 can also be lightly lifted to facilitate the oil well output fluid to enter the sampling tube 1.

[0027] Bosses 212 are respectively provided on the inner and outer surfaces of the cover 21 at the positions of the perforations 211, so as to achieve the effect of thickening the thickness at the perforations 211, and facilitate the guiding cooperation between the perforations 211 and the driving rod 3. Furthermore, the perforations 211 are light holes, and the gap between the driving rod 3 and the light holes constitutes a gas gap for the piston 4 to flow the gas inside and outside the sampling cylinder 1 during the exhaust stroke and the sampling stroke. This avoids the air pressure difference caused by the inability of air to enter and exit the inner cavity of the sampling cylinder between the piston 4 and the cover 2, thereby causing the piston 4 to be blocked in the guided sliding of the sampling cylinder 1.

[0028] A support structure 11 is also provided on the bottom wall of the sampling cylinder 1 to support the sampling cylinder 1 and prevent damage to the bottom wall. Preferably, the fluid control valve 6 is located inside the support structure 11, thereby preventing the fluid control valve 6 from being easily damaged due to being located outside.

[0029] The ratio of the diameter of the sampling cylinder 1 to the height of the cylinder is 1:1.5~2. In the present embodiment, the ratio of the diameter of the sampling cylinder 1 to the height of the cylinder is 1:2. The above-mentioned structure prevents the sampling cylinder 1 from being too short, which may cause the liquid phase to overflow from the sampling hole 7 during sampling and affect the sampling. On the other hand, it also prevents the height of the sampling cylinder 1 from being too high, which may cause more oil well production liquid to fill the inner cavity of the sampling cylinder 1 and cause unnecessary waste, thereby reducing the processing and use costs.

[0030] The operation process of the wellhead gas sampler of the utility model is as follows:

[0031] After assembling the wellhead gas sampler, close the sampling valve 8, open the fluid control valve 6, operate the driving rod 3 to slide along the perforation 211 from top to bottom, and then slide the piston 4 to the bottom wall of the cylinder, thereby emptying the gas in the inner cavity of the sampling cylinder 1 between the piston 4 and the fluid control valve 6. Connect the fluid control valve 6 to the oil well output liquid outlet of the oil well wellhead manifold, open the valve on the manifold, allow the oil well output liquid to enter the sampling cylinder 1 and push the piston 4 upward, and the liquid phase of the oil well output liquid entering the sampling cylinder 1 is separated from the gas, and the gas is located above the liquid phase. After the piston 4 continues to move upward and crosses the sampling hole 7, open the sampling valve 8, and the gas can be discharged from the hose 9 at the sampling valve 8. After the air in the hose 9 is emptied, connect the sampling bag to collect the gas sample. After the collection is completed, the sampling valve 7, the valve on the manifold and the fluid control valve 6 are closed in sequence, and then the fluid control valve 6 is connected to the waste liquid barrel and opened, and the drive rod 3 is pressed to discharge the oil well output fluid in the sampling tube 1 to prevent the oil well output fluid from polluting the environment. The above operation is when the pressure of the oil well output fluid in the manifold is sufficient to overcome the resistance between the piston 4 and the sampling tube 1. If the pressure of the oil well output fluid in the wellhead manifold is not enough to push the piston 4 to slide in the direction away from the bottom wall of the tube, the drive rod 4 can be manually pulled up to drive the piston 4 to slide. At this time, the wellhead gas sampler is used to extract the oil well output fluid in the manifold for sampling.

[0032] In other embodiments, the ratio of the diameter to the height of the sampling cylinder may be 1:1.5. In other embodiments, the ratio of the diameter to the height of the sampling cylinder may be 1:1.7.

[0033] In other embodiments, the bottom wall of the cylinder may no longer be provided with a tripod structure, but the sampling cylinder may be placed on an additional bracket.

[0034] In other embodiments, the through hole may no longer leave an air gap between the through hole and the driving rod, but an air hole for air circulation may be provided on the cover body.

[0035] In other embodiments, the boss may be provided only at the position of the perforation on the inner surface or outer surface of the cover. In other embodiments, the boss may no longer be provided, but the guide cooperation with the driving rod may be enhanced by thickening the size of the cover.

[0036] In other embodiments, the sealing cap may no longer be provided with a flange, but may be internally threadedly connected to the interior of the sampling barrel. In other embodiments, the sealing cap may also be welded to the sampling barrel.

[0037] In other embodiments, a cover may not be provided, but a protrusion for limiting the piston is provided on the side of the sampling tube away from the bottom wall of the tube, so as to prevent the piston from slipping out. In other embodiments, a cover or other limiting structure may not be provided, and the fluid sampling valve on the bottom wall of the tube or the valve of the wellhead manifold may be closed in time to prevent the sampled medium from rushing the piston out of the inner cavity of the sampling tube. In other embodiments, a cover and a driving rod may not be provided, and the piston is pushed by another device to discharge the medium in the sampling tube. When sampling, the fluid to be detected pushes the piston to move away from the bottom wall of the sampling tube.

[0038] In other embodiments, the hose connected to the sampling valve can also be used for sampling the sampling bottle. In other embodiments, a rigid tube for connecting the sampling bag can also be provided at the sampling valve. In other embodiments, the hose or rigid tube can no longer be provided, and the sampling bag can be directly connected to the sampling valve.

[0039] In other embodiments, the distance between the sampling hole and the end surface of the sampling tube mouth may also be one quarter or one sixth of the axial length of the tube side wall.

[0040] In other embodiments, the sampling hole may no longer be arranged perpendicular to the tube wall, but may be arranged as a straight hole inclined to the tube wall and penetrating the inner surface and the outer surface of the sampling cylinder.

[0041] In other embodiments, a pipeline is connected to the outer opening of the sampling hole, and the sampling valve is arranged on the pipeline.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the description and drawings of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wellhead gas sampler, comprising a sampling barrel having a barrel side wall and a barrel bottom wall, a fluid inlet being arranged on the barrel bottom wall, a piston being arranged in the sampling barrel and being slidably matched with the inner circumference of the barrel side wall in a sealed manner, and a piston sliding stroke having an exhaust stroke for moving close to the fluid inlet to exhaust the gas in the sampling barrel, and a sampling stroke for moving away from the fluid inlet to allow the fluid to enter the sampling barrel, characterized in that: The side wall of the cylinder is provided with a sampling hole which passes through the inner circumference and the outer circumference of the side wall of the cylinder. The sampling hole is a straight hole and has an inner orifice and an outer orifice. The inner orifice is connected to the inner cavity of the sampling cylinder and the sampling stroke of the piston includes a passing position which can pass over the inner orifice. The outer orifice position is directly or indirectly connected to a sampling valve.

2. The wellhead gas sampler according to claim 1, characterized in that: The sampling hole extends along the radial direction of the side wall of the cylinder.

3. The wellhead gas sampler according to claim 1 or 2, characterized in that: The distance from the sampling hole to the end surface of the tube mouth of the sampling tube is less than one third of the axial length of the tube side wall.

4. The wellhead gas sampler according to claim 1 or 2, characterized in that: The sampling valve is connected with a hose for communicating with a sampling bag.

5. The wellhead gas sampler according to claim 1 or 2, characterized in that: The wellhead gas sampler also includes a sealing cover connected to the mouth of the sampling barrel, the sealing cover includes a cover body and a flange, the flange is provided with an internal thread, the outer periphery of the mouth of the sampling barrel is provided with an external thread matching the internal thread, the wellhead gas sampler also includes a driving rod passing through the cover body and connected to the piston to drive the piston to slide in the sampling barrel, and the cover body is provided with a through hole for the driving rod to pass through.

6. The wellhead gas sampler according to claim 5, characterized in that: Bosses are respectively provided on the inner and outer surfaces of the cover body at the positions of the perforations.

7. The wellhead gas sampler according to claim 5, characterized in that: The through hole is a light hole, and the gap between the driving rod and the light hole constitutes a gas gap for the piston to flow through the gas inside and outside the sampling cylinder during the exhaust stroke and the sampling stroke.

8. The wellhead gas sampler according to claim 1 or 2, characterized in that: A tripod structure for supporting the sampling cylinder is arranged on the bottom wall of the cylinder.

9. The wellhead gas sampler according to claim 8, characterized in that: A fluid control valve is installed at the fluid inlet, and the fluid control valve is located on the inner side of the tripod structure.

10. The wellhead gas sampler according to claim 1 or 2, characterized in that: The ratio of the diameter to the height of the sampling cylinder is 1:1.5-2.

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