Full-bore sampler for oil well

Abstract

The invention discloses a full-bore sampler for an oil well. The full-bore sampler comprises an outer barrel, a sliding sleeve and a driving assembly, wherein the sliding sleeve is arranged in the outer barrel in a sliding manner; a plurality of sampling cavities are formed between the outer barrel and the sliding sleeve at intervals in the axial direction, two sample inlets are formed in the sliding sleeve at intervals in the axial direction and are the first sample inlet and the second sample inlet respectively, and pistons are arranged in the sampling cavities in a sliding mode; the driving assembly is arranged in the outer sleeve and used for driving the sliding sleeve to slide in the axial direction, a sample discharging opening is formed between the first sample injection opening and the second sample injection opening, and each sampling cavity is correspondingly provided with a pressure maintaining assembly; the driving assembly drives the sliding sleeve to move in the axial direction, so that the multiple sampling cavities are sequentially communicated with the first sample inlet and the second sample inlet, and when the sample discharging opening is communicated with the sampling cavities, the piston moves in the axial direction, so that the sampling cavities are sequentially subjected to sampling operation of sample feeding, sample discharging and then sample feeding. A plurality of pressure maintaining samples can be obtained at different depth points, and the representativeness of the samples and the accuracy of analysis data are improved.

Description

Technical Field

[0001] This invention relates to the field of downhole sampling technology, and more particularly to a full-bore sampler for oil wells. Background Technology

[0002] In both offshore and onshore oil and gas extraction, well sampling is a crucial step in obtaining the physical properties and compositional analysis of formation or subsea fluids (oil, water, oil- and water-containing miscible fluids, etc.). By sampling fluids in situ at different locations, depths, and production stages within the wellbore, important data such as oil density, viscosity, water cut, gas cut, dissolved gas content, component distribution, and the presence of solid particles and impurities can be obtained. This provides a reliable basis for reservoir description, dynamic model calibration, oil production scheme optimization, and surface treatment process design.

[0003] There are many types of existing oil well samplers, such as fixed-point piston samplers with packers, downhole sampling canisters, fixed-diameter samplers connected to the wellbore, and some pressure-maintaining downhole samplers. Most of these sampling devices use a single-point, single-sampling method, that is, the sampling port is opened at a predetermined depth or location to collect a sample once, and then the sample is taken out of the well for analysis by hoisting or other means.

[0004] However, the single-point, single-sampling method of existing samplers cannot obtain samples at different depths, resulting in insufficient sample quality and representativeness, and thus cannot directly reflect the changes in fluid composition and physical properties along the depth in the wellbore. Furthermore, repeated well runs or multiple changes of sampling locations are time-consuming and costly, and each operation increases the risk of wellbore contamination, well fluid agitation, and sample cross-contamination. Summary of the Invention

[0005] The purpose of this invention is to provide a downhole sampler that solves the problem that existing samplers cannot simultaneously perform multi-point sampling.

[0006] To achieve this objective, the present invention adopts the following technical solution: An oil well full-bore sampler includes an outer cylinder, a sliding sleeve slidably disposed inside the outer cylinder, and a drive assembly; Multiple sampling chambers are formed axially between the outer cylinder and the sliding sleeve. Two sampling ports are opened axially on the sliding sleeve, namely the first sampling port and the second sampling port. A piston is slidably arranged in the sampling chamber. The driving component is disposed in the outer sleeve and is used to drive the sliding sleeve to slide in the axial direction. A discharge port is provided between the first sample inlet and the second sample inlet, and each sampling chamber is provided with a pressure holding component. The front end of the first sample inlet and the second sample inlet is provided with a trigger to control the opening and closing of the pressure holding component. The driving component drives the sliding sleeve to move axially, causing the plurality of sampling chambers to sequentially connect with the first and second inlet ports. When the discharge port connects with the sampling chamber, the pressure-holding component is triggered, driving the piston to move axially, so that the sampling chamber sequentially performs a sampling operation of injection, discharge, and then injection. Optionally, Optionally, two sampling chambers are formed between the outer cylinder and the sliding sleeve. The two sampling chambers are a first sampling chamber and a second sampling chamber, respectively, along the direction from the upper end to the lower end of the outer cylinder. The pistons in the two sampling chambers are a first piston and a second piston, respectively.

[0007] Optionally, the full-bore sampler for oil wells further includes a mandrel, which is coaxially disposed inside the outer cylinder, with both ends of the outer cylinder connected to the mandrel, and the sliding sleeve slidably disposed between the mandrel and the outer cylinder; A partition ring is fixed on the inner wall of the outer cylinder. The partition ring divides the cavity formed between the outer cylinder and the mandrel into an upper cavity and a lower cavity. The sliding sleeve is located in the lower cavity. The side closer to the upper end of the outer cylinder is the upper cavity, and the side closer to the lower end of the outer cylinder is the lower cavity. Both the upper cavity and the lower cavity are sealed cavities.

[0008] Optionally, when the sliding sleeve is in its initial state, both the first and second inlets are located on the side of the first sampling chamber closest to the upper cavity.

[0009] Optionally, an airflow channel is provided in the outer cylinder, the airflow channel connects the upper cavity and the lower cavity, the driving assembly includes a pressure generator disposed in the upper cavity, the airflow channel is connected to the air inlet of the pressure generator, and the air outlet of the pressure generator passes through the partition ring and connects to the lower cavity.

[0010] Optionally, each of the sampling chambers is provided with a pressure holding assembly, which includes a driving part and a reset part. The driving part is used to drive the piston to move axially, and the reset part is used to reset the piston. The trigger includes a contact switch and a contact point. The contact switch is located on the inner wall of the outer cylinder, and the contact point is located on the sliding sleeve. The contact point is located between the first inlet and the outlet. The trigger is used to control the opening and closing state of the drive unit. When the contact is triggered, the outlet communicates with the first sampling chamber.

[0011] Optionally, a pressure-holding channel is provided in the outer cylinder, connecting the airflow channel and the sampling chamber. A pressure-holding cavity is provided in the outer cylinder, and the pressure-holding channel penetrates the pressure-holding cavity. The driving unit includes: An airtight switch is located in the airflow channel and on the side of the pressure-holding channel near the upper cavity. The contact switch is used to control the opening and closing of the airtight switch. The sliding plug slides within the pressure-holding cavity; A connecting rod, one end of which is fixed to the sliding seal, and the other end of which is fixed to the piston. The reset part is sleeved on the spring of the connecting rod.

[0012] Optionally, sealing rings are provided on both sides of the first and second injection ports on the outer wall of the sliding sleeve.

[0013] An oil well sampling method, employing the full-bore oil well sampler as described above, includes the following steps: S1. Lower the sampler to the predetermined depth inside the wellbore; S2. Start the drive assembly to drive the sliding sleeve to move along the first stroke, so that the second sample inlet on the sliding sleeve is connected to the uppermost sampling chamber, and the sample enters the sampling chamber to complete the initial filling. S3. The sliding sleeve continues to move a second stroke, so that the sampling chamber is sealed by the sliding sleeve, and then the discharge port is connected to the sampling chamber to discharge the sample initially filled in the sampling chamber; S4. The sliding sleeve continues to move for a third stroke, so that the first inlet is connected to the sampling chamber, and the fresh sample enters the sampling chamber to complete the formal sampling. S5. The sliding sleeve continues to move, so that the sampling chamber is sealed again, and triggers the pressure holding component corresponding to the sampling chamber. The pressure holding component drives the piston to move, applying and maintaining a predetermined pressure on the sample formally obtained in the sampling chamber. S6. Repeat steps S2 to S5 to connect the two inlet ports and the outlet ports to the remaining sampling chambers in sequence to obtain multiple pressure-holding fluid samples.

[0014] Compared with the prior art, the present invention has the following beneficial effects: In an oil well full-bore sampler provided in this embodiment of the invention, the drive assembly drives the sliding sleeve to move downwards for a first stroke, connecting the second inlet to the uppermost sampling chamber, allowing the sample to enter the sampling chamber. The sliding sleeve continues to move for a second stroke, sealing the sampling chamber again. Then, the sliding sleeve moves for a third stroke, connecting the discharge port to the sampling chamber, triggering the trigger element and activating the pressure-holding assembly, which drives the piston in the sampling chamber to move, allowing the sample in the sampling chamber to be discharged into the wellbore through the discharge port. The sliding sleeve moves for a fourth stroke, connecting the first inlet to the sampling chamber, allowing fresh, representative formation fluid to enter the sampling chamber through the first inlet. Then, the sliding sleeve moves for a fifth stroke, allowing the first inlet to slide past the sampling chamber, finally sealing the chamber. The trigger element at the front end of the first inlet is then triggered, activating the pressure-holding assembly, which applies and maintains a predetermined pressure higher than the bubble point pressure on the fluid sample in the sampling chamber, thereby ensuring that the sample remains in a single-phase state during the process of being lifted to the surface, preventing gas evolution. Therefore, by sliding the sleeve axially and sequentially aligning multiple sampling chambers, the entire process from cleaning and formal sampling to pressure holding can be completed in a single well operation. Multiple pressure-holding samples can be obtained at different depths along the wellbore, which greatly improves operational efficiency, reduces the time cost, operational risks, and wellbore disturbance caused by multiple trips in and out of the well, and significantly improves the representativeness of the samples and the accuracy of the analytical data. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0017] Figure 1 This is a schematic diagram of the structure of an oil well full-bore sampler.

[0018] Figure 2 This is a structural cross-sectional view of an oil well full-bore sampler.

[0019] Figure 3 for Figure 2 A magnified view of section A in the middle.

[0020] Figure 4 for Figure 2 A magnified view of section B in the middle.

[0021] Figure 5 for Figure 4 A magnified view of part D in the middle.

[0022] Figure 6 for Figure 2 A magnified view of section C.

[0023] Illustration: 1. Outer cylinder; 11. Separating ring; 12. Upper cavity; 13. Lower cavity; 14. Airflow channel; 15. Pressure holding channel; 16. Pressure holding chamber; 2. Sampling chamber; 21. First sampling chamber; 22. Second sampling chamber; 23. First piston; 24. Second piston; 3. Sliding sleeve; 31. First inlet; 32. Second inlet; 33. Discharge port; 4. Mandrel; 5. Drive assembly; 51. Air pressure generator; 6. Pressure holding assembly; 61. Drive unit; 611. Airtight switch; 612. Sliding plug; 613. Connecting rod; 62. Reset unit; 621. Spring; 7. Trigger; 71. Contact switch; 72. Contact; 8. Sealing ring. Detailed Implementation

[0024] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0026] This invention provides a full-bore sampler for oil wells, comprising an outer cylinder, a sliding sleeve slidably disposed inside the outer cylinder, and a drive assembly. Multiple sampling chambers are axially spaced between the outer cylinder and the sliding sleeve. Two inlets, a first inlet and a second inlet, are axially spaced on the sliding sleeve. A piston is slidably disposed within each sampling chamber. The drive assembly is disposed within the outer sleeve and is used to drive the sliding sleeve to slide axially. A discharge port is provided between the first and second inlets, and each sampling chamber is correspondingly provided with a pressure-holding assembly. The drive assembly drives the sliding sleeve to move axially, causing the multiple sampling chambers to sequentially connect with the first and second inlets. When the discharge port connects with a sampling chamber, the pressure-holding assembly is triggered, driving the piston to move axially, so that the sampling chambers sequentially perform sampling operations of injection, discharge, and re-injection.

[0027] In an oil well full-bore sampler provided in this embodiment of the invention, the drive assembly drives the sliding sleeve to move downwards for a first stroke, connecting the second inlet to the uppermost sampling chamber, allowing the sample to enter the sampling chamber. The sliding sleeve continues to move for a second stroke, sealing the sampling chamber again. Then, the sliding sleeve moves for a third stroke, connecting the discharge port to the sampling chamber, triggering the trigger element and activating the pressure-holding assembly, which drives the piston in the sampling chamber to move, allowing the sample in the sampling chamber to be discharged into the wellbore through the discharge port. The sliding sleeve moves for a fourth stroke, connecting the first inlet to the sampling chamber, allowing fresh, representative formation fluid to enter the sampling chamber through the first inlet. Then, the sliding sleeve moves for a fifth stroke, allowing the first inlet to slide past the sampling chamber, finally sealing the chamber. The trigger element at the front end of the first inlet is then triggered, activating the pressure-holding assembly, which applies and maintains a predetermined pressure higher than the bubble point pressure on the fluid sample in the sampling chamber, thereby ensuring that the sample remains in a single-phase state during the process of being lifted to the surface, preventing gas evolution. Therefore, by sliding the sleeve axially and sequentially aligning multiple sampling chambers, the entire process from cleaning and formal sampling to pressure holding can be completed in a single well operation. Multiple pressure-holding samples can be obtained at different depths along the wellbore, which greatly improves operational efficiency, reduces the time cost, operational risks, and wellbore disturbance caused by multiple trips in and out of the well, and significantly improves the representativeness of the samples and the accuracy of the analytical data.

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] like Figures 1-6 As shown, this embodiment of the invention provides a full-bore sampler for oil wells, used in scenarios where bottom fluids are obtained during oil and gas exploration or development. It aims to provide a sampler that can achieve multi-point sampling and ensure the quality of the sampled samples. Through structural improvements, this embodiment of the invention also has the advantages of improving sampling efficiency and reducing costs.

[0030] Example 1: like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in this embodiment, the oil well full-bore sampler includes an outer cylinder 1, a sliding sleeve 3 slidably disposed inside the outer cylinder 1, and a drive assembly 5. Multiple sampling chambers 2 are formed axially between the outer cylinder 1 and the sliding sleeve 3. Two inlets, a first inlet 31 and a second inlet 32, are spaced axially on the sliding sleeve 3. A piston is slidably disposed in each sampling chamber 2. The drive assembly 5 is disposed in the outer sleeve and is used to drive the sliding sleeve 3 to slide axially. A discharge port 33 is provided between the first inlet 31 and the second inlet 32, and each sampling chamber 2 is correspondingly provided with a pressure-holding assembly 6. The drive assembly 5 drives the sliding sleeve 3 to move axially, causing the multiple sampling chambers 2 to sequentially connect with the first inlet 31 and the second inlet 32. When the discharge port 33 connects with the sampling chamber 2, the pressure-holding assembly 6 is triggered, driving the piston to move axially, so that the sampling chambers 2 sequentially perform sampling operations of injection, discharge, and re-injection.

[0031] Specifically, the outer cylinder 1 can be a circular tube structure with connecting threads at both ends for connecting to the downhole tubing. The outer diameter of the outer cylinder 1 can be specifically set according to the diameter of the wellbore. The circular tube structure set at the top of the outer cylinder can be used to connect to the drilling vessel or the fixed lifting frame on the ground to drive the sampler to descend. The sliding sleeve 3 is coaxially set in the inner cavity of the outer cylinder 1 and can slide back and forth relative to the outer cylinder 1 along the axial direction under the drive of the drive assembly 5. A recessed annular groove can be opened on the inner wall of the outer cylinder 1, or spacer rings can be fixed at intervals on the inner wall of the outer cylinder 1. The annular groove or spacer rings together with the outer cylinder 1 and the sliding sleeve 3 can form a sealed sampling chamber 2. Multiple sampling chambers 2 are arranged at intervals along the axial direction of the outer cylinder 1, and each sampling chamber 2 is equipped with a piston that can slide along the axial direction.

[0032] Meanwhile, on the tube wall of the sliding sleeve 3, a first inlet 31, a discharge port 33, and a second inlet 32 ​​are sequentially provided axially from top to bottom. In the initial state, both the first inlet 31 and the second inlet 32 ​​are located above the uppermost sampling chamber 2, thus ensuring that all sampling chambers 2 are in a closed state. Each sampling chamber 2 is correspondingly provided with a pressure-holding assembly 6. The pressure-holding assembly 6 provides and maintains a preset pressure to the sampling chamber 2 by driving a piston to move axially. For example, the pressure-holding assembly 6 may include a chamber pre-filled with high-pressure nitrogen, a control valve, and a pressure-transmitting piston located within the chamber. The control valve is controlled by a trigger 7. When the control valve is open, the pressure-transmitting piston is pushed by nitrogen, thereby moving the piston. The trigger 7 is located on the sliding sleeve 3 or the outer cylinder 1 at the front end of the first inlet 31 and the second inlet 32, and is used to activate the pressure-holding assembly 6 when the sliding sleeve 3 moves to an appropriate position.

[0033] The workflow of the full-bore sampler in this embodiment of the invention is as follows: In the initial state, the sliding sleeve 3 is in the initial position, and the inlets of all sampling chambers 2 are sealed by the wall of the sliding sleeve 3. Then, the sampler is lowered to the target well depth. The drive assembly 5 drives the sliding sleeve 3 to move downward for a first stroke, so that the second inlet 32 ​​moves to the position corresponding to the uppermost sampling chamber 2 and connects with it. Under the action of pressure difference, the well fluid enters the sampling chamber 2 through the second inlet 32. The drive assembly 5 drives the sliding sleeve 3 to continue moving for a second stroke, so that the second inlet 32 ​​slides past the sampling chamber 2, and the sliding sleeve 3 seals the sampling chamber 2 again. Then, the drive assembly 5 drives the sliding sleeve 3 to move for a third stroke until the discharge port 33 connects with the sampling chamber 2. At this time, the trigger 7 is triggered. The pressure holding assembly 6 is activated, driving the piston in the sampling chamber 2 to move, allowing the sample in the sampling chamber 2 to be discharged into the wellbore through the discharge port 33. The drive assembly 5 drives the sliding sleeve 3 to move a fourth stroke, moving the first inlet 31 to a position communicating with the sampling chamber 2, allowing fresh, representative formation fluid to enter the sampling chamber 2 through the first inlet 31. Then, the sliding sleeve 3 moves a fifth stroke, allowing the first inlet 31 to slide past the sampling chamber 2, finally sealing the chamber. The trigger 7 at the front end of the first inlet 31 is triggered, activating the pressure holding assembly 6 to apply and maintain a predetermined pressure higher than its bubble point pressure to the fluid sample in the sampling chamber 2, thereby ensuring that the sample remains in a single-phase state during the process of being lifted to the surface and preventing gas evolution. Therefore, by sliding the axial direction of the sliding sleeve 3, multiple sampling chambers 2 can be sequentially aligned, and the entire process from cleaning and formal sampling to pressure holding can be completed in one well operation. Multiple pressure-holding samples can be obtained at different depths along the wellbore, which greatly improves the efficiency of operation, reduces the time cost, operational risks and wellbore disturbance caused by multiple trips in and out of the well, and significantly improves the representativeness of the samples and the accuracy of the analysis data.

[0034] Understandably, after completing the sampling and pressure holding of the first sampling chamber 2, the drive assembly 5 can drive the sliding sleeve 3 to continue moving to the next stroke position, repeating the above steps for the next sampling chamber 2. Thus, each sampler can sequentially undergo a cycle of initial filling through the second inlet 32, sealing, emptying through the outlet 33, formal sampling through the first inlet 31, and sealing and pressure holding, achieving continuous and automatic acquisition of multiple high-fidelity fluid samples from different depths or time periods during a single well operation.

[0035] like Figure 2 , Figure 3 and Figure 4 As shown, in an optional embodiment of the present invention, two sampling chambers 2 are formed between the outer cylinder 1 and the sliding sleeve 3. The two sampling chambers 2 are the first sampling chamber 21 and the second sampling chamber 22 respectively along the direction from the upper end to the lower end of the outer cylinder 1. The pistons in the two sampling chambers 2 are the first piston 23 and the second piston 24 respectively.

[0036] Meanwhile, the oil well full-bore sampler also includes a mandrel 4, which is coaxially disposed inside the outer cylinder 1. Both ends of the outer cylinder 1 are connected to the mandrel 4, and the sliding sleeve 3 is slidably disposed between the mandrel 4 and the outer cylinder 1. A partition ring 11 is fixed on the inner wall of the outer cylinder 1. The partition ring 11 divides the cavity formed between the outer cylinder 1 and the mandrel 4 into an upper cavity 12 and a lower cavity 13. The side closer to the upper end of the outer cylinder 1 is the upper cavity 12, and the side closer to the lower end of the outer cylinder 1 is the lower cavity 13. Both the upper cavity 12 and the lower cavity 13 are sealed cavities.

[0037] Specifically, the mandrel 4 is a tubular shaft with a through-hole in the middle. Both ends of the mandrel 4 can be provided with external threads for connection to the outer cylinder 1. The mandrel 4 is hollow inside, forming a full-bore flow channel. A through-hole can be started on the mandrel 4 at the position corresponding to the sampling chamber 2 to allow fluid samples to pass through. A filter screen can be installed in the through-hole to prevent large particles of impurities from entering the sampling chamber 2 and causing blockage. The outer cylinder 1 is sleeved on the outside of the mandrel 4, and the sliding sleeve 3 is coaxially sleeved on the mandrel 4 and located within the annular space formed by the mandrel 4 and the outer cylinder 1. It can move along the axial direction of the mandrel 4. Sliding; A partition ring 11 is fixedly installed on the inner wall of the outer cylinder 1. The partition ring 11 divides the annular space between the mandrel 4 and the outer cylinder 1 into two mutually isolated sealed cavities along the axial direction: an upper cavity 12 located above and a lower cavity 13 located below. The sliding sleeve 3 is located in the lower cavity 13. On the tube wall of the sliding sleeve 3, a first sample inlet 31, a sample outlet 33, and a second sample inlet 32 ​​are sequentially opened from top to bottom. Two sets of pressure-holding components 6 are correspondingly arranged, respectively corresponding to the first sampling cavity 21 and the second sampling cavity 22. Among them, the mandrel 4 serves as the core support and full-bore flow channel, which helps to enhance the overall pressure and torsional resistance of the sampler, making it suitable for harsh downhole environments such as deep wells and highly deviated wells, and ensuring the coaxiality and smoothness of the reciprocating motion of the sliding sleeve 3.

[0038] It should be noted that in the initial state, when the sliding sleeve 3 has not slid, both the first sampling port 31 and the second sampling port 32 are located on the side of the first sampling chamber 21 closer to the upper cavity 12; after the sampling of the first sampling chamber 21 and the second sampling chamber 22 is completed, both the first sampling port 31 and the second sampling port 32 are located on the side of the second sampling chamber 22 away from the upper cavity 12.

[0039] like Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, in this embodiment of the invention, an airflow channel 14 is provided in the outer cylinder 1, the airflow channel 14 connects the upper cavity 12 and the lower cavity 13, the drive assembly 5 includes a pressure generator 51 disposed in the upper cavity 12, the airflow channel 14 is connected to the air inlet of the pressure generator 51, and the air outlet of the pressure generator 51 passes through the partition ring 11 and is connected to the lower cavity 13.

[0040] Specifically, the drive assembly 5 is pneumatically driven. The air pressure generator 51 is fixedly installed inside the upper cavity 12. For example, the air pressure generator 51 can be a high-pressure gas cylinder release device controlled by a ground signal. When started, it can discharge high-pressure gas from the outlet. The airflow channel 14 is machined inside the wall of the outer cylinder 1 or forms a connecting path through an attached pipeline. One end of the airflow channel 14 is connected to the airflow generator inside the upper cavity 12, and the other end is connected to the end of the lower cavity 13 away from the sliding sleeve 3. The airflow channel 14 is connected to the air inlet of the airflow generator, and the air outlet of the airflow generator passes through the partition ring 11 and finally connects to the upper space of the lower cavity 13, that is, the space between the top of the sliding sleeve 3 and the partition ring 11.

[0041] For example, during sampling, the tool is lowered to the target depth, with the sliding sleeve 3 located at the top of the lower cavity 13. The space of the lower cavity 13, the air passage, the upper cavity 12, and the interior of the pressure generator 51 located below the sliding sleeve 3 are pre-filled with inert working gas (such as nitrogen). After receiving an external signal, the pressure generator 51 is activated, generating high-pressure gas that enters between the top of the sliding sleeve 3 and the partition ring 11, thereby pushing the sliding sleeve 3 to move towards the bottom of the lower cavity 13. As the sliding sleeve 3 moves downward, the volume of the bottom of the lower cavity 13 continuously decreases, the working gas sealed inside is compressed, and is transported back to the air inlet of the pressure generator 51 in the upper cavity 12 through the air passage, continuously replenishing the gas source for the generator. The sliding sleeve 3 is used to compress and recycle the gas in the lower chamber 13, resulting in high energy efficiency. This reduces reliance on external pre-charged high-pressure gas tanks, allows for a longer stroke of the sliding sleeve 3 and more sampling chambers 2, and improves the tool's single-operation capability and reliability. Furthermore, as the sliding sleeve 3 moves downwards, the compression process of the gas at its bottom provides damping and buffering effects, which, in conjunction with the top driving thrust, makes the sliding sleeve 3's movement more stable and controllable, avoiding impact motion and facilitating precise alignment of the inlet. Simultaneously, the entire drive system is enclosed within the upper chamber 12 and lower chamber 13 inside the outer cylinder 1 and mandrel 4, making the gas-driven sliding sleeve 3 less susceptible to wellbore pressure and fluid properties, exhibiting extremely high reliability and stability under complex well conditions such as high pressure, high temperature, and corrosive fluids.

[0042] like Figure 4 and Figure 5As shown, in this embodiment of the invention, each sampling chamber 2 is provided with a pressure holding component 6. The pressure holding component 6 includes a driving part 61 and a reset part 62. The driving part 61 is used to drive the piston to move axially, and the reset part 62 is used to reset the piston. The contact element includes a contact switch 71 and a contact 72. The contact switch 71 is located on the inner wall of the outer cylinder 1, and the contact 72 is located on the sliding sleeve 3. The contact 72 is located between the first sample inlet 31 and the sample outlet 33. The trigger 7 is used to control the opening and closing state of the driving part 61, and when the contact element is triggered, the sample outlet 33 is connected to the first sampling chamber 21.

[0043] Specifically, the drive unit 61 can use an electric telescopic rod or pneumatic drive to drive the piston to move axially. For example, a storage chamber pre-filled with high-pressure nitrogen can be used, with an electrically controlled valve body installed inside. The storage chamber is connected to the upper chamber of the piston in the corresponding sampling chamber 2 through a pressure transmission channel. When the electrically controlled valve body opens, high-pressure nitrogen enters above the piston, pushing the piston downward and applying a holding pressure to the fluid sample below the piston. The reset unit 62 can be an elastic element installed above the piston. In the non-holding pressure state or after the sample is released, the reset unit 62 provides elastic force to drive the piston back to the initial top position of the sampling chamber 2. The contact switch 71 is fixedly installed on the inner wall of the outer cylinder 1, and the contact 72 is installed on the sliding sleeve 3. When the contact 72 slides with the sliding sleeve 3 to the contact position with the contact switch 71, it connects with the first sampling chamber 21 corresponding to the discharge port 33. At this time, the contact switch 71 is opened, which can control the drive unit 61 to start, thereby driving the piston to compress the sample in the sampling chamber 2, so that the sample is discharged from the discharge port 33, which can clean the sampling chamber 2, so as to ensure the reliability of sample quality.

[0044] For example, a one-way valve can also be installed in the discharge port 33, allowing the liquid in the sampling chamber 2 to flow only from the sampling chamber 2 into the well shaft, and the opening and closing of the one-way valve can also be controlled by the contact switch 71; during the discharge cleaning process, a special cleaning agent can also be added to the sampling chamber 2 to improve the cleaning effect and further ensure the quality of the sample.

[0045] Furthermore, a pressure-holding channel 15 is provided in the outer cylinder 1, connecting the airflow channel 14 and the sampling chamber 2. A pressure-holding cavity 16 is provided in the outer cylinder 1, and the pressure-holding channel 15 passes through the pressure-holding cavity 16. The drive unit 61 includes an airtight switch 611, a sliding plug 612, and a connecting rod 613. The airtight switch 611 is located in the airflow channel 14 and is located on the side of the pressure-holding channel 15 near the upper cavity 12. A contact switch 71 is used to control the opening and closing of the airtight switch 611. The sliding plug 612 slides in the pressure-holding cavity 16. One end of the connecting rod 613 is fixed to the sliding plug 612, and the other end is fixed to the piston. A reset part 62 is sleeved on the spring 621 of the connecting rod 613.

[0046] Specifically, a pressure-holding channel 15 is formed inside the wall of the outer cylinder 1. One end of the pressure-holding channel 15 is connected to the main airflow channel 14, and the other end leads to the corresponding sampling chamber 2. Along the path of the pressure-holding channel 15, a pressure-holding cavity 16 is formed inside the outer cylinder 1, and the pressure-holding channel 15 passes through the pressure-holding cavity 16. An airtight switch 611 is installed in the airflow channel 14 and is located at the upper end of the connection point of the pressure-holding channel 15. The opening and closing state of the airtight switch 611 is controlled by the contact switch 71. The sliding plug 612 slides against the inner wall of the pressure-holding cavity 16, dividing the pressure-holding cavity 16 into two non-communicating sides. One end of the connecting rod 613 is fixedly connected to the center of the sliding plug 612, and the other end passes through the pressure-holding channel 15 and is finally fixedly connected to the center of the piston. The reset part 62 is a compression spring 621 sleeved on the connecting rod 613. One end of the spring 621 abuts against the end wall of the pressure-holding cavity 16, and the other end abuts against the sliding plug 612.

[0047] When the contact switch 71 is not triggered, the airtight switch 611 remains open, allowing the gas in the lower chamber 13 to smoothly enter the upper chamber 12. The gas branching into the pressure-holding channel 15 can exert a certain thrust on the piston, causing the piston to continuously apply pressure to the sampling chamber 2. When the contact switch 71 is triggered, the airtight switch 611 closes, and all the gas in the airflow channel 14 enters the pressure-holding channel 15 as the driving force to move the piston.

[0048] The specific workflow of this embodiment of the invention is as follows: In the initial state, the airtight switch 611 remains open, and the airflow channel 14 allows gas to smoothly enter the upper cavity 12 from the lower cavity 13. The elastic force of the spring 621 is transmitted through the connecting rod 613, keeping the piston at the top of the sampling cavity 2, and the sliding plug 612 is in the initial position of the pressure-holding cavity 16. When the sliding sleeve 3 moves to the precise position where the discharge port 33 communicates with the sampling cavity 2, the contact 72 on the sliding sleeve 3 triggers the contact switch 71, the airtight switch 611 closes, the high pressure in the main airflow channel 14 drives the gas pressure-holding channel 15, and acts on the sliding plug 612, overcoming the preload of the return spring 621, pushing the piston to move, and applying pressure to the sampling cavity 2, thereby discharging the sample in the sampling cavity 2 from the discharge port 33 or maintaining the pressure in the sampling cavity 2. When the contact switch 71 closes, the sliding plug 612 of the spring 621 returns to its original position, and at the same time, the piston is pulled back to the top of the sampling cavity 2 through the connecting rod 613.

[0049] For example, sealing rings 8 are provided on both sides of the first inlet 31 and the second inlet 32 ​​on the outer wall of the sliding sleeve 3. By providing sealing cavities on the outer wall of the sliding sleeve 3 on both sides of the first inlet 31 and the second inlet 32, it is beneficial to improve the sealing effect between the outer wall of the sliding sleeve 3 and the inner wall of the outer cylinder 1, and avoid leakage of fluid samples.

[0050] Example 2: This invention also provides an oil well sampling method, using the above-described full-bore oil well sampler, comprising the following steps: S1. Lower the sampler to the predetermined depth inside the wellbore; S2. Start the drive assembly 5, drive the sliding sleeve 3 to move along the first stroke, so that the second sample inlet 32 ​​on the sliding sleeve 3 is connected to the uppermost sampling chamber 2, and the sample enters the sampling chamber 2 to complete the initial filling. S3, the sliding sleeve 3 continues to move in the second stroke, so that the sampling chamber 2 is sealed by the sliding sleeve 3, and then the discharge port 33 is connected to the sampling chamber 2 to discharge the sample initially filled in the sampling chamber 2. S4. The sliding sleeve 3 continues to move in the third stroke, so that the first inlet 31 is connected to the sampling chamber 2, and the fresh sample enters the sampling chamber 2 to complete the formal sampling. S5, the sliding sleeve 3 continues to move, so that the sampling chamber 2 is sealed again, and triggers the pressure holding component 6 corresponding to the sampling chamber 2. The driving piston of the pressure holding component 6 moves to apply and maintain a predetermined pressure on the sample formally obtained in the sampling chamber 2. S6. Repeat steps S2 to S5 to connect the two inlet ports and the outlet port 33 to the remaining sampling chambers 2 in sequence to obtain multiple pressure-holding fluid samples.

[0051] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A full-bore sampler for oil wells, characterized in that, It includes an outer cylinder (1), a sliding sleeve (3) slidably disposed inside the outer cylinder (1), and a drive assembly (5); Multiple sampling chambers (2) are formed axially between the outer cylinder (1) and the sliding sleeve (3). Two sampling ports are opened axially on the sliding sleeve (3), namely the first sampling port (31) and the second sampling port (32). A piston is slidably arranged in the sampling chamber (2). The driving component (5) is located in the outer sleeve and is used to drive the sliding sleeve (3) to slide in the axial direction. A discharge port (33) is provided between the first sample inlet (31) and the second sample inlet (32). Each sampling chamber (2) is provided with a pressure holding component (6). The front ends of the first sample inlet (31) and the second sample inlet (32) are provided with triggers (7) for controlling the opening and closing of the pressure holding component (6). The driving component (5) drives the sliding sleeve (3) to move axially, so that the multiple sampling chambers (2) are connected to the first inlet (31) and the second inlet (32) in sequence. When the discharge port (33) is connected to the sampling chamber (2), the pressure holding component (6) is triggered and drives the piston to move axially, so that the sampling chamber (2) performs sampling operations of injection, discharge and injection in sequence.

2. The oil well full-bore sampler according to claim 1, characterized in that, Two sampling chambers (2) are formed between the outer cylinder (1) and the sliding sleeve (3). The two sampling chambers (2) are the first sampling chamber (21) and the second sampling chamber (22) respectively along the direction from the upper end to the lower end of the outer cylinder (1). The pistons in the two sampling chambers (2) are the first piston (23) and the second piston (24) respectively.

3. The oil well full-bore sampler according to claim 2, characterized in that, The oil well full-bore sampler also includes a mandrel (4), which is coaxially disposed inside the outer cylinder (1). Both ends of the outer cylinder (1) are connected to the mandrel (4), and the sliding sleeve (3) is slidably disposed between the mandrel (4) and the outer cylinder (1). A partition ring (11) is fixed on the inner wall of the outer cylinder (1). The partition ring (11) divides the cavity formed between the outer cylinder (1) and the mandrel (4) into an upper cavity (12) and a lower cavity (13). The sliding sleeve (3) is located in the lower cavity (13). The side closer to the upper end of the outer cylinder (1) is the upper cavity (12), and the side closer to the lower end of the outer cylinder (1) is the lower cavity (13). Both the upper cavity (12) and the lower cavity (13) are sealed cavities.

4. The oil well full-bore sampler according to claim 3, characterized in that, When the sliding sleeve (3) is in its initial state, the first inlet (31) and the second inlet (32) are both located on the side of the first sampling cavity (21) close to the upper cavity (12).

5. The full-bore sampler for oil wells according to claim 3, characterized in that, An airflow channel (14) is provided in the outer cylinder (1), the airflow channel (14) connects the upper cavity (12) and the lower cavity (13), the drive assembly (5) includes a pressure generator (51) disposed in the upper cavity (12), the airflow channel (14) is connected to the air inlet of the pressure generator (51), and the air outlet of the pressure generator (51) passes through the partition ring (11) and connects to the lower cavity (13).

6. The oil well full-bore sampler according to claim 5, characterized in that, Each of the sampling chambers (2) is provided with a pressure holding assembly (6). The pressure holding assembly (6) includes a driving part (61) and a reset part (62). The driving part (61) is used to drive the piston to move axially, and the reset part (62) is used to reset the piston. The trigger (7) includes a contact switch (71) and a contact (72). The contact switch (71) is located on the inner wall of the outer cylinder (1), and the contact (72) is located on the sliding sleeve (3). The contact (72) is located between the first inlet (31) and the outlet (33). The trigger (7) is used to control the opening and closing state of the drive unit (61), and when the contact is triggered, the outlet (33) is connected to the first sampling chamber (21).

7. The oil well full-bore sampler according to claim 6, characterized in that, The outer cylinder (1) has a pressure-holding channel (15) connecting the airflow channel (14) and the sampling chamber (2). A pressure-holding cavity (16) is located in the outer cylinder (1), and the pressure-holding channel (15) passes through the pressure-holding cavity (16). The driving unit (61) includes: An airtight switch (611) is provided in the airflow channel (14) and located on the side of the pressure-holding channel (15) near the upper cavity (12). The contact switch (71) is used to control the opening and closing of the airtight switch (611). The sliding plug (612) slides within the pressure-holding cavity (16); A connecting rod (613), one end of which is fixed to the sliding plug (612), and the other end of which is fixed to the piston. The reset part (62) is sleeved on the spring (621) of the connecting rod (613).

8. The oil well full-bore sampler according to claim 2, characterized in that, On the outer wall of the sliding sleeve (3), sealing rings (8) are provided on both sides of the first injection port (31) and the second injection port (32).

9. An oil well sampling method, employing the full-bore oil well sampler as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Lower the sampler to the predetermined depth inside the wellbore; S2. Start the drive assembly (5) to drive the sliding sleeve (3) along the first stroke, so that the second inlet (32) on the sliding sleeve (3) is connected to the uppermost sampling chamber (2), and the sample enters the sampling chamber (2) to complete the initial filling. S3. The sliding sleeve (3) continues to move for a second stroke, so that the sampling cavity (2) is sealed by the sliding sleeve (3), and then the discharge port (33) is connected to the sampling cavity (2) to discharge the sample initially filled in the sampling cavity (2); S4. The sliding sleeve (3) continues to move for a third stroke, so that the first inlet (31) is connected to the sampling chamber (2), and the fresh sample enters the sampling chamber (2) to complete the formal sampling. S5. The sliding sleeve (3) continues to move, so that the sampling chamber (2) is sealed again, and triggers the pressure holding component (6) corresponding to the sampling chamber (2). The pressure holding component (6) drives the piston to move, applying and maintaining a predetermined pressure on the sample formally obtained in the sampling chamber (2). S6. Repeat steps S2 to S5 to connect the two inlet ports and the outlet port (33) to the remaining sampling chambers (2) in sequence to obtain multiple pressure-holding fluid samples.

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